JP2016081908A - Method for inspecting magnetron - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inspect a magnetron with high accuracy.SOLUTION: In a method according to one embodiment, the life of a magnetron is determined on the basis of comparison between a current parameter indicating a current state of the magnetron obtained from one or more measurement values for specifying a current state of the magnetron at the time when a time period equal to or more than a predetermined time period lapses from the start of generation of a high-frequency by a magnetron, and when a difference between a power of a progressive wave and a setting power is a first predetermined value or less, and when a power of a reflection wave is a second predetermined value or less, and an initial parameter indicating an initial state of the magnetron corresponding to the current parameter.SELECTED DRAWING: Figure 6

Description

  Embodiments of the present invention relate to a method for inspecting a magnetron.

  In the manufacture of an electronic device such as a semiconductor device, a plasma processing apparatus is used to perform a process such as etching or film formation on an object to be processed. The plasma processing apparatus has an apparatus that generates energy to be introduced into the processing container in order to generate plasma of the processing gas introduced into the processing container. As such an apparatus, a magnetron that generates a microwave is known.

  The state of the magnetron changes from the initial state immediately after its creation or immediately after incorporation into the plasma processing apparatus as the usage time elapses. For example, the state of the magnetron changes due to the consumption of the surface carbonized layer constituting the filament. When the state of the magnetron changes in this way, the state of the generated plasma changes, which adversely affects the processing on the object to be processed. Therefore, it is necessary to inspect the magnetron and grasp the replacement time of the magnetron.

  As a technique for inspecting a magnetron, for example, a technique described in Patent Document 1, that is, International Publication No. 2013/146655 has been developed. The technique described in Patent Document 1 determines whether or not the magnetron has reached the end of its life by comparing a parameter indicating the current state of the magnetron and a parameter indicating the initial state of the magnetron. When it is determined that the lifetime has been reached, a signal that prompts replacement of the magnetron is output.

International Publication No. 2013/146655

  The inventor of the present application detects a measurement value used for obtaining a parameter indicating the state of the magnetron, for example, a measurement value of a traveling wave power, a measurement value of a reflected wave power, a measurement value of an anode voltage, and a measurement value of an anode current. We have found that depending on the timing, the magnetron cannot be properly inspected. Therefore, it is necessary to inspect the magnetron with higher accuracy, for example, to determine the lifetime of the magnetron, by using measured values detected at the appropriate time.

  In one aspect, a method for inspecting a magnetron is provided. The method includes: (a) causing the magnetron to start generating a high frequency based on the set power; (b) detecting one or more measured values for identifying the state of the magnetron; and (c) using the magnetron. A step of determining whether or not a predetermined time length has elapsed since the start of the generation of the high frequency; and (d) a difference between the traveling wave power based on the high frequency generated by the magnetron and the preset power A step of determining whether or not it is equal to or less than a predetermined value of 1, and (e) the power of the reflected wave output from the directional coupler provided between the magnetron and the load is equal to or less than a second predetermined value And (f) a time equal to or longer than the predetermined time length has elapsed since the start of generation of high frequency by the magnetron, and a difference between the traveling wave power and the set power is a first predetermined power. A current parameter indicating a current state of the magnetron obtained from the one or more measured values of the magnetron at a time when a use condition in which the power of the reflected wave is equal to or less than a second predetermined value is satisfied; Determining the lifetime of the magnetron based on a comparison with an initial parameter indicative of an initial state of the magnetron corresponding to the parameter of.

  Current parameters obtained from measurements detected immediately after the generation of high frequency by the magnetron, for example, high frequency conversion efficiency, anode voltage, anode current, and / or peak frequency of the traveling wave are unstable and are Stabilizes after elapse. In the above method, when a predetermined time length has elapsed from the start of generation of the high frequency of the magnetron, the power of the traveling wave becomes substantially the same as the set power, and the power of the reflected wave becomes substantially zero, that is, Since the lifetime of the magnetron is determined using the current parameters obtained from the measured values at the time when the use conditions are satisfied, the magnetron can be inspected with high accuracy.

  In one embodiment, the current parameter includes the current high frequency conversion efficiency of the magnetron, and the high frequency conversion efficiency is a value obtained by dividing the traveling wave power contained in the one or more measured values by the input power to the magnetron. In the step of determining the lifetime of the magnetron of this embodiment, when the current high-frequency conversion efficiency included in the current parameter is lower than a predetermined ratio with respect to the initial high-frequency conversion efficiency of the magnetron included in the initial parameter In addition, the lifetime of the magnetron may be detected.

In one embodiment, a high-frequency conversion efficiency correction value is obtained by subtracting the current high-frequency conversion efficiency offset value from the current high-frequency conversion efficiency, and the high-frequency conversion efficiency correction value is an initial parameter. The lifetime of the magnetron may be detected when the initial high-frequency conversion efficiency of the magnetron included in is reduced by a predetermined ratio or more. For example, the method of one embodiment is:
By inputting the elapsed time length from the start time point to the time point when the use condition is satisfied to the predetermined first function, the first basic offset value ηB _OFFSET (T _L ), which is the output of the predetermined first function. The predetermined first function is an elapsed time length t _A from the start of a period in which the magnetron continuously generates a high frequency under a predetermined traveling wave power setting to any point in time during the period. And the absolute value of the difference between the high-frequency conversion efficiency of the magnetron at the arbitrary time and the convergence value of the high-frequency conversion efficiency of the magnetron when the magnetron continuously generates a high frequency under a predetermined traveling wave power setting. Defining a relationship with a first basic offset value ηB _OFFSET (t _A ) that is a value;
The coefficient B _η (P _fm ), which is the output of the predetermined second function, is obtained by inputting the measured value P _fm of the traveling wave power at the time when the use condition is satisfied to the predetermined second function. is a step, the predetermined second function can consist of any Shinko Nami power P _a, the maximum variation of the high frequency conversion efficiency of the magnetron of Toki the magnetron continuously generate a high frequency under Settei of said given Shinko Nami power Defining a relationship between a predetermined value as a quantity and a coefficient B _η (P _A ) representing a ratio of the first basic offset value ηB _OFFSET (t _A ) to a predetermined maximum value;
The offset value of the high-frequency conversion efficiency of the magnetron obtained in the period in which the magnetron is generating high frequency immediately before the stop period in which the magnetron has stopped generating high frequency immediately before the start time is the first basic offset value ηB. Obtaining a coefficient C _η by dividing by a predetermined maximum value of _OFFSET (t _A );
The step of obtaining the coefficient D _η (T _S ), which is the output of the predetermined third function, by inputting the time length T _S of the stop period to the predetermined third function, An arbitrary stop time length t _{SA at} which the magnetron stops the generation of the high frequency, and a maximum of the high frequency conversion efficiency of the magnetron when the magnetron continuously generates the high frequency immediately after the generation of the high frequency for a predetermined stop time length. The relationship between the fluctuation amount and the coefficient D _η (t _SA ) representing the ratio of the maximum fluctuation amount of the high frequency conversion efficiency of the magnetron when the magnetron continuously generates a high frequency immediately after the arbitrary stop time. Defining the steps; and
Using the first basic offset value ηB _OFFSET (T _L ), the coefficient B _η (P _fm ), the coefficient C _η , and the coefficient D _η (T _S ) in the equation (1), the offset value of the high frequency conversion efficiency of the magnetron _obtaining η _OFFSET ;

The current high-frequency conversion efficiency η _m and the offset value η _OFFSET , which are values obtained by dividing the traveling wave power included in one or more measured values at the time when the use condition is satisfied, by the input power to the magnetron, are expressed in Equation (2) A step of obtaining a correction value η _C of the high-frequency conversion efficiency,

Is further included. In the method of this embodiment, the current parameter includes the correction value η _C of the high frequency conversion efficiency. In the step of determining the life of the magnetron, the correction value η _C of the high frequency conversion efficiency included in the current parameter is the initial value. When the initial high-frequency conversion efficiency of the magnetron included in the parameter is lower than a predetermined rate, the lifetime of the magnetron is detected.

  In one embodiment, the current parameter includes the absolute value of the magnetron anode voltage measurement contained in one or more measurements at the time the usage condition is met as the current anode voltage of the magnetron. In the step of determining the lifetime of the magnetron of this embodiment, the absolute value of the current anode voltage of the magnetron included in the current parameter is a predetermined value with respect to the absolute value of the initial anode voltage of the magnetron included in the initial parameter. If it has increased above, the life of the magnetron may be detected.

In one embodiment, a correction value for the absolute value of the magnetron anode voltage is obtained by subtracting an offset value of the current magnetron anode voltage from the absolute value of the current magnetron anode voltage measurement. The lifetime of the magnetron may be detected when the correction value of the absolute value of the magnetron anode voltage is increased by a predetermined value or more with respect to the absolute value of the initial anode voltage of the magnetron included in the initial parameter. . For example, the method of one embodiment is:
The elapsed time length _TL from the start time to the time when the use condition is satisfied is input to a predetermined fourth function, whereby the second basic offset value VB _OFFSET (T _L ), and the predetermined fourth function is an elapsed time length from the start of a period in which the magnetron continuously generates a high frequency under a predetermined traveling wave power setting to an arbitrary point in the period. The absolute value of the difference between t _A and the convergence value of the magnetron anode voltage when the magnetron continuously generates a high frequency under a predetermined traveling wave power setting Defining a relationship with a second basic offset value VB _OFFSET (t _A ) that is a value;
The coefficient B _V (P _fm ), which is the output of the predetermined fifth function, is obtained by inputting the measured value P _fm of the traveling wave power at the time when the use condition is satisfied to the predetermined fifth function. a step up of the magnetron anode voltage when the predetermined fifth function, and any forward power P _a, the magnetron is continuously generating a high frequency in the set of a said given forward power P _a Defining a relationship between a coefficient B _V (P _A ) representing a ratio of a predetermined value as a fluctuation amount to a predetermined maximum value of the second basic offset value VB _OFFSET (t _A );
The offset value of the anode voltage of the magnetron obtained in the period in which the magnetron is generating high frequency immediately before the stop period in which the magnetron has stopped generating high frequency immediately before the start time is the second basic offset value VB. Obtaining a coefficient C _V by dividing by a predetermined maximum value of _OFFSET (t _A );
The step of obtaining the coefficient D _V (T _S ), which is the output of the predetermined sixth function, by inputting the time length T _S of the stop period to the predetermined sixth function, Arbitrary stop time length t _{SA at} which the magnetron stops generating high frequency, and maximum fluctuation of the anode voltage of the magnetron when the magnetron continuously generates high frequency immediately after stopping the generation of high frequency for a predetermined stop time length The relationship between the magnetron and the coefficient D _V (t _SA ) representing the ratio of the maximum fluctuation amount of the anode voltage of the magnetron when the magnetron continuously generates a high frequency immediately after the magnetron is stopped is the arbitrary stop time length. The step;
Using the second basic offset value VB _OFFSET (T _L ), the coefficient B _V (P _fm ), the coefficient C _V , and the coefficient D _V (T _S ) in the equation (3), the offset value V of the anode voltage of the magnetron _{Obtaining OFFSET} ; and

A correction value for the absolute value of the anode voltage by using the current anode voltage measurement value V _m and the offset value V _OFFSET of the magnetron included in one or more measurement values at the time when the use condition is satisfied, in equation (4). Obtaining V _C ;

Is further included. In the step of determining the lifetime of the magnetron of this embodiment, the correction value V _C of the absolute value of the anode voltage included in the current parameter is predetermined with respect to the absolute value of the initial anode voltage of the magnetron included in the initial parameter. When the value increases more than the value, the life of the magnetron is detected.

  In one embodiment, the current parameter includes a measurement of the magnetron anode current included in one or more measurements at the time the usage condition is met as the current anode current of the magnetron. In the step of determining the lifetime of the magnetron in this embodiment, the current anode current of the magnetron included in the current parameter is increased by a predetermined value or more with respect to the initial anode current of the magnetron included in the initial parameter. In addition, the lifetime of the magnetron may be detected.

In one embodiment, a correction value for the magnetron anode current is obtained by adding the current magnetron anode current measurement value and the current magnetron anode current offset value to obtain a magnetron anode current correction value. The life of the magnetron may be detected when the correction value is increased by a predetermined value or more than the initial anode current of the magnetron included in the initial parameters. For example, the method of one embodiment is:
The elapsed time length _TL from the start time to the time when the use condition is satisfied is input to a predetermined seventh function, whereby the third basic offset value IB _OFFSET (T _L ), and the predetermined seventh function is the elapsed time length t _A from the start of a period in which the magnetron generates a high frequency under a predetermined traveling wave power setting to any point in time during the period The absolute value of the difference between the magnetron anode current at the arbitrary time and the convergence value of the magnetron anode current when the magnetron continuously generates a high frequency under the predetermined traveling wave power setting. Defining a relationship with a third basic offset value IB _OFFSET (t _A );
The coefficient B _I (P _fm ), which is the output of the predetermined eighth function, is obtained by inputting the measured value P _fm of the traveling wave power at the time when the use condition is satisfied to the predetermined eighth function. a step, the predetermined eighth function, and any forward power P _a, the maximum variation of the anode current of the magnetron when the magnetron is continuously generating a high frequency under setting said given traveling wave power Determining a relationship between a predetermined value as a coefficient B _I (P _A ) representing a ratio of a third basic offset value IB _OFFSET (t _A ) to a predetermined maximum value;
The offset value of the anode current of the magnetron obtained in the period in which the magnetron is generating high frequency immediately before the stop period in which the magnetron has stopped generating high frequency immediately before the start time is the third basic offset value. by dividing the predetermined maximum value, and obtaining the coefficients C _I,
This is a step of obtaining the coefficient D _I (T _S ), which is the output of the predetermined ninth function, by inputting the time length T _S of the stop period to the predetermined ninth function, and the predetermined ninth function is: Arbitrary stop time length t _{SA at} which the magnetron stops high frequency generation, and maximum fluctuation of the anode current of the magnetron when the magnetron continuously generates high frequency immediately after stopping the generation of high frequency for a predetermined stop time length The relationship of the coefficient D _I (t _SA ) representing the ratio of the maximum fluctuation amount of the anode current of the magnetron when the magnetron continuously generates a high frequency immediately after the magnetron is stopped to the amount of the arbitrary stop time. , And the step
The third basic offset value IB _OFFSET (T _L ), the coefficient B _I (P _fm ), the coefficient C _I , and the coefficient D _I (T _S ) are used in Equation (5), and the offset value I of the magnetron anode current I _{Obtaining OFFSET} ; and

Measurements I _m and the offset value I _OFFSET current anode current of the magnetron used conditions are included in one or more measurements of the time which is filled with the equation (6), the correction value I _C of anode current Seeking steps,

Is further included. In determining the magnetron lifetime of this embodiment, the correction value I _C of anode current in the current parameter has increased by more than a predetermined value with respect to the magnetron initial anode current included in the initial parameters In some cases, the lifetime of the magnetron is detected.

  In one embodiment, the current parameter includes a measured value of the peak frequency of the traveling wave included in one or more measured values at the time when the use condition is satisfied, as the current peak frequency of the traveling wave. In the step of determining the lifetime of the magnetron of this embodiment, the current peak frequency of the traveling wave included in the current parameter is lower than a predetermined value with respect to the initial peak frequency of the traveling wave included in the initial parameter. In some cases, the lifetime of the magnetron may be detected.

In one embodiment, a correction value for the peak frequency of the traveling wave is obtained by subtracting an offset value of the peak frequency of the traveling wave at the current time point from the measurement value of the current peak frequency of the traveling wave, thereby obtaining a traveling wave peak frequency correction value. The lifetime of the magnetron may be detected when the difference between the correction value of the peak frequency and the initial peak frequency of the traveling wave included in the initial parameter is equal to or greater than a predetermined value. For example, the method of one embodiment is:
By inputting the elapsed time length _TL from the start time point to the time point when the use condition is satisfied to the predetermined tenth function, the fourth basic offset value FB _OFFSET (T _L ), and the predetermined tenth function is an elapsed time length from the start of a period in which the magnetron continuously generates a high frequency under a predetermined traveling wave power setting to any point in time during the period t _A , the peak frequency of the traveling wave of the magnetron at the arbitrary time point, and the peak frequency of the traveling wave of the magnetron when the magnetron continuously generates a high frequency under the setting of the predetermined traveling wave power Defining a relationship with a fourth basic offset value FB _OFFSET (t _A ) that is an absolute value of a difference from the convergence value;
The coefficient B _F (P _fm ), which is the output of the predetermined eleventh function, is obtained by inputting the measured value P _fm of the traveling wave power at the time when the use condition is satisfied to the predetermined eleventh function. a step, the predetermined eleventh function, the maximum of the traveling wave peak frequency when the optional forward power P _a, the magnetron is continuously generates a high-frequency settings of a said given forward power P _a Defining a relationship between a predetermined value as a fluctuation amount and a coefficient B _F (P _A ) representing a ratio of the fourth basic offset value FB _OFFSET (t _A ) to a predetermined maximum value;
The offset value of the peak frequency of the traveling wave obtained in the period in which the magnetron is generating high frequency immediately before the stop period in which the magnetron has stopped generating high frequency immediately before the start time is the predetermined fourth basic offset value. Obtaining a coefficient C _F by dividing by the maximum value of
This is a step of obtaining a coefficient D _F (T _S ) that is an output of the predetermined twelfth function by inputting the time length T _S of the stop period to the predetermined twelfth function, and the predetermined twelfth function is: Arbitrary stop time length t _{SA at} which the magnetron stops high frequency generation, and maximum fluctuation of the peak frequency of the traveling wave when the magnetron continuously generates high frequency immediately after stopping the generation of high frequency for a predetermined stop time length The relationship of the coefficient D _F (t _SA ) representing the ratio of the maximum fluctuation amount of the traveling wave peak frequency when the magnetron continuously generates a high frequency immediately after the magnetron is stopped is the arbitrary stop time length. The step;
By using the fourth basic offset value F _BOFFSET (T _L ), coefficient B _F (P _fm ), coefficient C _F , and coefficient D _F (T _S ) in equation (7), the offset of the peak frequency of the traveling wave _{Obtaining a} value F _OFFSET ;

Using the measured value F _m and the offset value F _OFFSET of the traveling wave peak frequency included in one or more measured values at the time when the use condition is satisfied, the correction value F of the traveling wave peak frequency is used in Equation (8). _{Determining C} ;

Is further included. In determining the magnetron lifetime of this embodiment, reduced more than a predetermined value relative to the initial peak frequency of the traveling wave correction value F _C of the traveling wave of peak frequencies in the current parameters are included in the initial parameters If it does, it detects the lifetime of the magnetron.

  Note that the lifetime of the magnetron may be determined using two or more parameters among the above-described high-frequency conversion efficiency, anode voltage, anode current, peak frequency, and correction values thereof.

  The method of an embodiment may further include predicting the remaining time to the current life of the magnetron.

  In the step of predicting the remaining time length of one embodiment, the current magnetron usage time length corresponding to the current high frequency conversion efficiency is referred to by referring to the data associating the magnetron usage time length with the high frequency conversion efficiency of the magnetron. And the difference between the preset magnetron life time length and the current magnetron usage time length may be obtained as the remaining time length.

In the step of predicting the remaining time length of another embodiment, the current usage time length t _c of the magnetron, the initial high-frequency conversion efficiency η _ic , and the current high-frequency conversion efficiency η _m are used to Based on the constant A,

Using the predetermined high frequency conversion efficiency η _d at the lifetime of the magnetron, the calculated constant A, and the initial high frequency conversion efficiency η _ic , the life time length t _d is calculated based on the equation (10),

The difference between the calculated life duration t _d and the current use time length t _c may be calculated as a residual duration. Although the magnetron has a machine difference, in this embodiment, the constant A reflecting the machine difference is calculated, and the remaining time is calculated based on the calculated constant A. Therefore, the remaining time is obtained with higher accuracy.

  As described above, the magnetron can be inspected with high accuracy.

It is a figure which shows an example of a plasma processing apparatus roughly. It is a top view which shows the antenna of the plasma processing apparatus shown in FIG. It is a figure which illustrates the structure of a microwave generator. It is a figure which shows the magnetron of the microwave generator shown in FIG. It is a figure which shows the structure of 4E tuner of the microwave generator shown in FIG. 2 is a flow diagram illustrating a method for inspecting a magnetron according to one embodiment. It is a figure which illustrates the initial parameter memorized by memory. It is a figure which shows the change according to the time of the high frequency conversion efficiency, the absolute value of an anode voltage, the anode current, and the peak frequency of a traveling wave. It is a flowchart which shows the process which can be used for step ST7 of the method shown in FIG. It is a flowchart which shows the process which can be used for step ST7 of the method shown in FIG. It is a flowchart which shows the process which can be used for step ST7 of the method shown in FIG. It is a flowchart which shows the process which can be used for step ST7 of the method shown in FIG. It is a flowchart which shows the process which can be used for step ST8 of the method shown in FIG. It is a flowchart which shows the process which can be used for step ST8 of the method shown in FIG. It is a figure which illustrates the relationship between the usage time length of a magnetron, and the high frequency conversion efficiency of a magnetron. 6 is a flowchart illustrating a method for inspecting a magnetron according to another embodiment. It is a figure which shows the time-dependent change of the absolute value of the anode voltage of a magnetron, an anode current, and high frequency conversion efficiency. It is a flowchart which shows the process which can be utilized in step S29 of the method shown in FIG. It is a flowchart which shows the process which can be utilized in step S29 of the method shown in FIG. It is a flowchart which shows the process which can be utilized in step S29 of the method shown in FIG. It is a flowchart which shows the process which can be utilized in step S29 of the method shown in FIG. It is a figure which shows the time-dependent change of the absolute value of the anode voltage of a magnetron. It is a figure which shows the time-dependent change of the absolute value of the anode voltage of a magnetron. It is a figure which shows the relationship between the time length of the stop period of a magnetron, and the maximum variation | change_quantity of the anode voltage of a magnetron in the period which has generate | occur | produced the high frequency immediately after the said stop period.

  Hereinafter, various embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  First, an example of a plasma processing apparatus including a magnetron inspected by a method according to an embodiment will be described. FIG. 1 is a diagram schematically illustrating an example of a plasma processing apparatus. The plasma processing apparatus 10 shown in FIG. 1 is an apparatus for performing plasma processing on the workpiece W. The plasma processing that can be performed using the plasma processing apparatus 10 is, for example, plasma processing such as etching or CVD.

  The plasma processing apparatus 10 includes a processing container 12, a gas supply unit 13, a mounting table 14, a plasma generation mechanism 19, and a control unit 15. The processing container 12 provides an internal space for performing plasma processing on the workpiece W. The gas supply unit 13 is configured to supply a processing gas used for plasma processing into the processing container 12. The mounting table 14 is configured to hold the workpiece W thereon. The plasma generation mechanism 19 is configured to generate plasma in the processing container 12. The control unit 15 is configured to control the overall operation of the plasma processing apparatus 10. The control unit 15 controls the entire plasma processing apparatus 10 such as the flow rate of the gas supplied from the gas supply unit 13 and the pressure in the processing container 12.

  The processing container 12 has a bottom 21 and a side wall 22. The bottom 21 is provided below the mounting table 14. The side wall 22 has a substantially cylindrical shape and extends upward from the edge of the bottom 21. An exhaust hole 23 for exhaust is provided in the bottom portion 21 of the processing container 12 so as to penetrate a part thereof.

  On the upper side of the processing container 12, a lid 24, a dielectric window 16, and an O-ring 25 are provided. The lid portion 24 is disposed on the upper side of the processing container 12, and the O-ring 25 is interposed between the lid portion 24 and the dielectric window 16. An opening is formed on the upper side of the processing container 12, and the opening is closed by the lid portion 24, the dielectric window 16, and the O-ring 25 to ensure airtightness.

  The gas supply unit 13 includes a first gas supply unit 26 and a second gas supply unit 27. The 1st gas supply part 26 supplies the gas which goes to the center of the to-be-processed object W through a 1st flow path. The second gas supply unit 27 supplies gas via a second flow path provided above and outside the workpiece W. The first flow path of the first gas supply unit 26 communicates with the gas supply hole 30a. The gas supply hole 30 a is provided at the center in the radial direction of the dielectric window 16. The first gas supply unit 26 is connected to a gas supply system 29. The gas supply system 29 is configured to adjust the flow rate of the gas supplied to the first gas supply unit 26. The second gas supply unit 27 includes a plurality of gas supply holes 30b. These gas supply holes 30 b are provided in a part on the upper side of the side wall 22. The plurality of gas supply holes 30b are provided at equal intervals in the circumferential direction. The first gas supply unit 26 and the second gas supply unit 27 can be supplied with the same type of gas from the same gas source. Note that another type of gas may be supplied to the first gas supply unit 26 and the second gas supply unit 27.

  The mounting table 14 provides a lower electrode. A high frequency power source 38 for high frequency bias is electrically connected to the lower electrode via a matching unit 39. The high frequency power supply 38 outputs, for example, a high frequency of 13.56 MHz with a predetermined power (bias power). The matching unit 39 accommodates a matching unit for matching between the impedance on the high-frequency power source 38 side and the impedance on the load side such as electrodes, plasma, and the processing container 12. In the matching unit of the matching unit 39, a blocking capacitor for generating a self-bias is included. In the plasma processing, the bias voltage can be supplied to the mounting table 14 as necessary.

  Further, the mounting table 14 also provides an electrostatic chuck, and the workpiece W can be held thereon. Further, the mounting table 14 may include a temperature adjusting mechanism 33 such as a heater for heating. The mounting table 14 is supported by an insulating cylindrical support portion 31 that extends vertically upward from the lower side of the bottom portion 21. The exhaust hole 23 described above is formed at the center of the bottom 21 of the processing container 12, and the cylindrical support part 31 penetrates the exhaust hole 23. Therefore, the exhaust hole 23 has an annular shape. An exhaust device is connected to the lower side of the annular exhaust hole 23 via an exhaust pipe. The exhaust device has a vacuum pump such as a turbo molecular pump. With this exhaust device, the inside of the processing container 12 can be depressurized to a predetermined pressure.

  The plasma generation mechanism 19 is provided outside the processing container 12. The plasma generation mechanism 19 includes a microwave generator 41a. The microwave generator 41a generates a microwave as a high frequency for plasma generation. The plasma generation mechanism 19 has a dielectric window 16. The dielectric window 16 is disposed on the upper side of the processing container 12 so as to face the mounting table 14. The dielectric window 16 introduces the microwave from the microwave generator 41 a into the processing container 12.

  The plasma generation mechanism 19 has an antenna 17. The antenna 17 is provided on the dielectric window 16. The antenna 17 is formed with a plurality of slot holes for radiating microwaves to the dielectric window 16. Further, the plasma generation mechanism 19 has a dielectric plate 18. The dielectric plate 18 is disposed on the antenna 17. The dielectric plate 18 propagates the microwave introduced by a coaxial waveguide 36 described later in the radial direction. The dielectric plate 18 has a function of delaying the microwave.

  The microwave generator 41 a is connected to the upper part of the coaxial waveguide 36 via the mode converter 34 and the rectangular waveguide 35. For example, the TE mode microwave from the microwave generator 41 a passes through the rectangular waveguide 35 and is converted into the TEM mode by the mode converter 34. The TEM mode microwave from the mode converter 34 propagates through the coaxial waveguide 36. The detailed configuration of the microwave generator 41a will be described later. In addition, the rectangular waveguide 35 side with respect to the microwave generator 41a becomes a load described later.

  The dielectric window 16 has a substantially disk shape and is made of a dielectric such as quartz or alumina. A part of the lower surface 28 of the dielectric window 16 is formed with an annular recess 37 that is recessed in a tapered shape or a recess that is recessed in a circular shape in order to facilitate the generation of a standing wave by the introduced microwave. Has been. Such recesses 37 can efficiently generate plasma immediately below the bottom surface of the dielectric window 16.

  The antenna 17 has a thin plate shape and a disk shape. FIG. 2 is a plan view showing an antenna of the plasma processing apparatus shown in FIG. As shown in FIG. 2, a plurality of slot holes 20 are formed in the antenna 17. Each of the plurality of slot holes 20 has a long hole shape. The plurality of slot holes 20 constitute a plurality of slot pairs. Each of the plurality of slot pairs includes two slot holes extending in a direction orthogonal to or intersecting each other. The plurality of slot pairs are arranged along one or more concentric circles.

  The microwave from the microwave generator 41 a is propagated to the dielectric plate 18 through the coaxial waveguide 36. The microwave propagates between the antenna 17 and the cooling jacket 32 radially outward in the dielectric plate 18 and is radiated from the plurality of slot holes 20 of the antenna 17 to the dielectric window 16. The microwave transmitted through the dielectric window 16 generates an electric field immediately below the dielectric window 16. Thereby, plasma is generated in the processing container 12.

  Hereinafter, the configuration of the microwave generator 41a will be described in detail. FIG. 3 is a diagram illustrating the configuration of the microwave generator. FIG. 4 is a diagram showing a magnetron of the microwave generator shown in FIG. FIG. 5 is a diagram showing the configuration of the 4E tuner of the microwave generator shown in FIG.

  As shown in FIG. 3, the microwave generator 41 a includes a magnetron 42, a high voltage power supply 43, and a filament power supply 44. The magnetron 42 is a high frequency oscillator that generates a microwave as a high frequency. The high voltage power supply 43 is configured to supply a voltage to the magnetron 42. Further, the filament power supply 44 is configured to supply power to the filament constituting the cathode electrode 46 a of the magnetron 42.

  A circuit 45 is provided between the magnetron 42 and the high voltage power supply 43. In the microwave generator 41a, an anode current is supplied from the high voltage power supply 43 side to the magnetron 42 side via the circuit 45. As shown in FIG. 4, a filament is incorporated in the circuit 45 inside the magnetron 42. This filament constitutes the cathode electrode 46a. The cathode electrode 46 a is connected to the negative electrode side of the high voltage power supply 43. Further, an anode electrode 46 b provided inside the magnetron 42 is connected to the positive electrode side of the high-voltage power supply 43. The positive electrode side of the high-voltage power supply 43, that is, the anode electrode 46b is grounded. Therefore, the anode voltage described later is measured as a negative value.

  The magnetron 42 generates a microwave 48 by the anode electrode 46b and the cathode electrode 46a when an anode current is supplied from the high voltage power source 43 to the anode electrode 46b. In addition, the filament which comprises the cathode electrode 46a, the anode vane which forms the anode electrode 46b, etc. are machined products manufactured by machining.

  As shown in FIG. 3, the microwave generator 41a further includes an isolator 49, a directional coupler 54, and a 4E tuner 51 as a matching unit. The directional coupler 54 is connected to the magnetron 42 via an isolator 49. The isolator 49 is configured by using one terminal of a circulator as a passive element as a dummy load 59. That is, the first terminal on the magnetron 42 side of the isolator 49 is connected to an oscillation unit (see FIG. 5) including the magnetron 42, and the second terminal on the 4E tuner 51 side of the isolator 49 is connected to the 4E tuner 51. The third terminal of the isolator 49 is connected to the dummy load 59. Thereby, the isolator 49 can transmit a high frequency signal in one direction from the magnetron 42 to the load 50 side.

  As shown in FIG. 5, the 4E tuner 51 includes movable short-circuit portions 52a, 52b, 52c, and 52d. The movable short-circuit portions 52a, 52b, 52c, and 52d are each provided with a movable short-circuit plate. These movable short-circuit plates are provided at intervals in the microwave traveling direction. The 4E tuner 51 includes three probes 53a, 53b, and 53c. These probes 53a, 53b, and 53c are provided on the magnetron 42 side with respect to the movable short-circuit portion 52a. The probes 53a, 53b, and 53c are provided at an interval of a distance of 1/8 of the fundamental frequency λ, that is, λ / 8, in the microwave traveling direction. Further, the amount of protrusion of the tuning bar corresponding to each of the probes 53a to 53c is calculated by an arithmetic circuit 53d connected to the probes 53a, 53b, and 53c.

  The 4E tuner 51 is connected to the load 50 via the rectangular waveguide 35. The load 50 includes a member such as the mode converter 34 that is located on the downstream side of the rectangular waveguide 35. A directional coupler 54 is provided on the magnetron 42 side with respect to the movable short-circuit portion 52a of the 4E tuner 51. The directional coupler 54 is a bidirectional coupler. The directional coupler 54 does not have to face the probes 53a, 53b, and 53c.

As shown in FIG. 3, a detector 90 and a detector 92 are connected to the directional coupler 54. The detector 90 detects the traveling wave, that is, the power of the microwave traveling from the magnetron 42 side to the load 50 side. The detector 90 outputs an analog signal corresponding to the detected traveling wave power. The analog signal from the detector 90 is converted into a digital value, that is, a measured value P _fm of traveling wave power, through the amplifier 102a and the A / D converter 104a of the control circuit 100. The measured value P _fm of the traveling wave power is input to the processor 110. The detector 92 detects the reflected wave, that is, the power of the microwave traveling from the load 50 side to the magnetron 42 side. The detector 92 outputs an analog signal corresponding to the detected power of the reflected wave. The analog signal from the detector 92 is converted into a digital value, that is, a reflected wave power measurement value P _rm via the amplifier 102b and the A / D converter 104b of the control circuit 100. The reflected wave power measurement value P _rm is input to the processor 110.

The processor 110 of the control circuit 100 is connected to the terminal T1 via the amplifier 102g and the A / D converter 104g. An analog signal corresponding to the set power is input to the terminal T1. The analog signal from the terminal T1 is converted into a digital value, that is, set power P _sin through the amplifier 102g and the A / D converter 104g. The set power P _sin represents the microwave power to be supplied to the load 50. Based on the set power P _sin , the measured value P _fm of the traveling wave power, and the measured value P _rm of the reflected wave power, the processor 110 sets the traveling wave power of the microwave generator 41a to match the set power P _sin . The high voltage power supply 43 and the filament power supply 44 are controlled. Specifically, the processor 110 outputs a control signal (digital signal) for controlling the voltage of the high-voltage power supply 43. This control signal is converted into an analog control signal by the D / A converter 104e and amplified by the amplifier 102e. Analog control signals _{V a,} which is amplified by the amplifier 102e is applied to a high voltage power supply 43. Thereby, the high voltage power supply 43 is controlled. In addition, the processor 110 outputs a control signal (digital signal) for controlling the voltage of the filament power supply 44. This control signal is converted into an analog control signal by the D / A converter 104f and amplified by the amplifier 102f. The analog control signal _Vf amplified by the amplifier 102f is supplied to the filament power supply 44. Thereby, the filament power supply 44 is controlled.

  The control circuit 100 includes a processor 110, an amplifier 102a, an amplifier 102b, an amplifier 102e, an amplifier 102f, an amplifier 102g, an A / D converter 104a, an A / D converter 104b, a D / A converter 104e, and a D / A conversion. In addition to the amplifier 104f and the A / D converter 104g, an amplifier 102c, an amplifier 102d, an amplifier 102h, an A / D converter 104c, an A / D converter 104d, an A / D converter 104h, and a memory 112 are further provided. Yes.

The processor 110 is connected to the voltage monitor 120 via the amplifier 102c and the A / D converter 104c. The voltage monitor 120 measures the anode voltage of the magnetron 42 and outputs an analog signal corresponding to the anode voltage. This analog signal is converted into a digital value, that is, a measured value V _m of the anode voltage via the amplifier 102c and the A / D converter 104c. The measured value V _m of the anode voltage is input to the processor 110.

The processor 110 is connected to the current monitor 122 via the amplifier 102d and the A / D converter 104d. The current monitor 122 measures the anode current and outputs an analog signal corresponding to the anode current. This analog signal is a digital value through the amplifier 102d, and the A / D converter 104d, i.e., is converted into measured values _{I m} of the anode current. This anode current measurement value _Im is input to the processor 110.

The processor is connected to the frequency detector 94 via the amplifier 102h and the A / D converter 104h. The frequency detector 94 is connected to the directional coupler 54, detects the peak frequency of the traveling wave, and outputs an analog signal representing the peak frequency. This analog signal is converted into a digital signal via the amplifier 102h and the A / D converter 104h. This digital signal is input to the processor 110 as a measured value F _m of the peak frequency of the traveling wave.

Further, a terminal T2 and a terminal T3 are connected to the processor 110. The operation signal MW _on for operating the magnetron 42 is supplied to the terminal T2. The processor 110 controls the high-voltage power supply 43 and the filament power supply 44 in response to the operation signal MW _on , and causes the magnetron 42 to generate a microwave. In the following description, when the operation signal MW _on is “1”, the magnetron 42 is operated to generate a microwave, and when the operation signal MWon is “0”, the generation of the microwave of the magnetron 42 is performed. Shall be stopped. The operation signal MW _on is set to “1” during the period in which the magnetron 42 is generating microwaves.

  On the other hand, when it is determined that the magnetron 42 has reached the end of its life by the processing described later, the processor 110 outputs an exchange request signal REQ to the terminal T3. This terminal T3 can be connected to an alarm device. When the alarm device receives the replacement request signal, the alarm device generates an alarm to prompt the operator of the plasma processing apparatus 10 to replace the magnetron 42. This alarm may be a sound or may be displayed on a display.

  The processor 110 is connected to the external computer device 130. The connection between the external computer device 130 and the processor 110 is a bidirectional connection. The external computer device 130 can read data in the memory 112 connected to the processor 110 via the processor 110, and transmits data from the external computer device 130 to send the data to the processor. It is also possible to write to the memory 112 via 110.

  Further, the processor 110 can execute processing for inspecting the magnetron 42. The inspection of the magnetron 42 includes determining the life of the magnetron 42. Also, in one embodiment, the inspection of the magnetron 42 includes a prediction of the remaining time length until the life of the magnetron 42. The processor 110 operates in accordance with a program stored in a memory outside or inside the processor 110 in order to execute a process for inspecting the magnetron 42.

  Hereinafter, a process related to the inspection of the magnetron 42 by the processor 110 will be described, and a method for inspecting the magnetron according to an embodiment will be described. FIG. 6 is a flow diagram illustrating a method for inspecting a magnetron according to one embodiment. In the method MT shown in FIG. 6, an initial parameter indicating an initial state of the magnetron 42 is used. Accordingly, initial parameters are first stored in the memory 112 prior to execution of the method MT.

  The initial parameters may be provided as data representing initial specifications from the manufacturer of the magnetron 42 or the operator of the plasma processing apparatus 10 and stored in the memory 112. When storing the initial parameters in the memory 112, the initial parameters may be transferred from the external computer device 130 to the memory 112 via the processor 110. Alternatively, the initial parameter may be acquired from a measurement value for specifying the state of the magnetron 42 actually measured immediately after the magnetron 42 is incorporated into the plasma processing apparatus 10 and stored in the memory 112. In this case, similarly to the acquisition of the current parameters of the magnetron 42 described later, a time longer than a predetermined time has elapsed from the start of the generation of the high frequency by the magnetron 42, and the set power and traveling wave power are substantially reduced. The initial parameters are acquired from the measured values when the reflected wave power becomes substantially zero, that is, the measured values when the use conditions are satisfied. Further, when storing the initial parameter acquired from the measurement value in the memory 112, the initial parameter is transferred from the processor 110 to the memory 112.

FIG. 7 is a diagram illustrating the initial parameters stored in the memory. As shown in FIG. 7, the memory 112 can store initial parameters in a table format. The first column from the left in FIG. 7 is the set power P _set . Initial parameter is dependent on the size of the set power _{P The set,} in association with the N setting different sizes power _{P set (1) ~P set (} N), the initial parameters are stored. In the example shown in FIG. 7, the initial anode currents I _i (1) to I _i (N) and the absolute value V _{i of the} initial anode voltage are associated with the set powers P _set (1) to P _set (N), respectively. (1) to V _i (N), initial high-frequency conversion efficiency η _i (1) to η _i (N), and initial peak frequencies F _i (1) to F _i (N) are stored. The initial high frequency conversion efficiency is defined as a value obtained by dividing the initial traveling wave power by the absolute value of the product of the initial anode current and the initial anode voltage.

Refer to FIG. 6 again. The method MT is executed after the initial parameters described above are stored in the memory 112. In the method MT, the operation signal MW _on is input to the processor 110 via the terminal T2, the set power P _sin is input via the terminal T1, and a predetermined time from the start of generation of the high frequency by the magnetron 42, that is, the microwave. A current parameter indicating the current state of the magnetron 42 is obtained from the measured value when the long time has elapsed.

  Reference is now made to FIG. FIG. 8 is a diagram showing changes in high frequency conversion efficiency, the absolute value of the anode voltage, the anode current, and the peak frequency of the traveling wave according to time. The high frequency conversion efficiency, the absolute value of the anode voltage, the anode current, and the peak frequency of the traveling wave (that is, the frequency of the bottom graph) shown in FIG. 8 are examples of current parameters indicating the state of the magnetron 42. As shown in FIG. 8, the high-frequency conversion efficiency, the absolute value of the anode voltage, the anode current, and the peak frequency of the traveling wave have unstable values in the period immediately after the start of the microwave generation by the magnetron 42. . Specifically, during the period in which the magnetron 42 continuously generates high frequency, the high frequency conversion efficiency, the absolute value of the anode voltage, and the peak frequency of the traveling wave gradually decrease and reach their convergent values. In addition, the anode current gradually increases and reaches its convergence value. Therefore, the magnetron 42 cannot be accurately inspected even using the current parameters acquired immediately after the start of microwave generation by the magnetron 42. On the other hand, as shown in FIG. 8, the high-frequency conversion efficiency, the absolute value of the anode voltage, the anode current, and the peak frequency of the traveling wave are predetermined time lengths (for example, 10 times) from the start of continuous generation of microwaves by the magnetron 42. It takes a stable value after the elapse of time. Therefore, the magnetron 42 can be inspected with high accuracy by using the current parameters when a predetermined time length has elapsed from the start of the generation of microwaves by the magnetron 42.

For this reason, in the method MT, it is necessary to measure the elapsed time from the start of input of the operation signal MW _on which is “1”. Therefore, in one example, a timer (T _ON ) is used, and the timer is initialized by the processor 110 in step ST1.

In the subsequent step ST2, the operating signal MW _on , the traveling wave power measurement value P _fm , the reflected wave power measurement value P _rm , the anode current measurement value I _m , the anode voltage measurement value V _m , and the traveling wave peak Detection of the frequency measurement F _m is performed by the processor 110.

In subsequent step ST3, the processor 110 determines whether or not the measured value P _fm of the traveling wave power detected in step ST1 is greater than 0 and whether or not the operation signal MW _on is “1”. . That is, it is determined whether or not generation of high frequency by the magnetron 42 is started. In this step ST3, when it is determined that the traveling wave power measurement value P _fm is 0 or less and the operation signal MW _on is “0”, generation of high frequency by the magnetron 42 has not started. Therefore, the process from step ST1 is repeated. On the other hand, when it is determined in step ST3 that the measured value P _fm of the traveling wave power is greater than 0 or the operation signal MW _on is “1”, generation of high frequency by the magnetron 42 is started. Therefore, in the following step ST4, the timer (T _ON ) is counted up by the processor 110.

In the subsequent step ST5, the processor 110 determines whether or not the time when the measurement value in the latest step ST2 is detected is the time when a predetermined time length or more has elapsed since the start of the generation of the high frequency by the magnetron 42. . Specifically, when the count value of the timer (T _ON ) is smaller than a predetermined value, a time longer than a predetermined time length from the start of generation of high frequency by the magnetron 42 is detected at the time of detection of the latest measured value in step ST2. It is determined that the time has not passed. On the other hand, when the count value of the timer (T _ON ) is equal to or greater than a predetermined value, a time of a predetermined time length or more has elapsed since the start of generation of a high frequency by the magnetron 42 at the time of detection of the measurement value in the latest step ST2. It is determined that this is the point in time. If it is determined in step ST5 that the most recent measurement value detected in step ST2 is not the time when a predetermined time length or more has elapsed since the start of generation of the high frequency by the magnetron 42, the process from step ST2 is performed again. The process is repeated. On the other hand, if it is determined in step ST5 that the measurement value of the most recent step ST2 is detected is a time when a predetermined time length or more has elapsed from the start of generation of high frequency by the magnetron 42, the following step The process of ST6 is executed by the processor 110.

In step ST6, it is determined whether or not the set power P _sin and the traveling wave power are substantially the same, and the reflected wave power is substantially zero. For example, whether or not the difference between the measured value P _fm of the traveling wave power and the set power P _sin is equal to or smaller than a first predetermined value and the measured value P _rm of the reflected wave power is equal to or smaller than a second predetermined value. Is determined by the processor 110. In Step ST6, when it is determined that the set power P _sin and the traveling wave power (measured value P _fm ) are not substantially the same, or the reflected wave power (measured value P _rm ) is not substantially 0, the magnetron The operation of 42 is still considered unstable. Therefore, the process from step ST2 is executed again. On the other hand, when it is determined that the set power P _sin and the traveling wave power (measured value P _fm ) are substantially the same, and the reflected wave power (measured value P _rm ) is substantially 0, in the subsequent step ST7 The lifetime of the magnetron 42 is determined by the processor 110.

  9 to 12 are flowcharts showing processes that can be used in step ST7 of the method shown in FIG. In the life determination in step ST7, one or more of the plurality of processes shown in FIGS. 9 to 12 can be executed. Each of the plurality of processes shown in FIG. 9 to FIG. 12 is a magnetron obtained from the current measurement value which is the measurement value at the time when the determination criterion of step ST5 and the determination criterion of step ST6 described above, that is, the use condition is satisfied. Whether or not the magnetron 42 has reached the end of its life is determined based on a comparison between a current parameter indicating the current state of the magnetron and an initial parameter indicating the initial state of the magnetron 42. Hereinafter, the processing shown in each of FIGS. 9 to 12 will be described.

  In the process shown in FIG. 9, the life of the magnetron 42 is reduced based on the comparison between the current high-frequency conversion efficiency as a current parameter indicating the current state of the magnetron 42 and the initial high-frequency conversion efficiency of the magnetron 42 as an initial parameter. It is determined whether it has reached.

Specifically, in the process shown in FIG. 9, first, in step ST701, the current high-frequency conversion efficiency η _m is calculated as a current parameter indicating the current state of the magnetron 42. As shown in FIG. 9, the current high-frequency conversion efficiency η _m depends on the input power, that is, the absolute value of the product of the current anode current measurement value I _m and the current anode voltage measurement value V _m. It is calculated as a value obtained by dividing the measured value P _fm of the wave power. Note that the current measured value I _m of the anode current, the measured value V _{m of} the current anode voltage, and the measured value P _fm of the current traveling wave power are respectively the anode current detected in step ST2 immediately before the execution of step ST701. Measurement value I _m , anode voltage measurement value V _m , and traveling wave power measurement value P _fm .

In subsequent step ST702, initial parameters are derived. Here, the initial high-frequency conversion efficiency η _ic is derived. Specifically, in step ST702, when the set power P _set stored in the memory 112, that is, any of P _set (1) to P _set (N) is the same as the set power P _sin , P _set The initial high-frequency conversion efficiency η _i associated with the set power P _set (j) that is the same as the set power P _sin among (1) to P _set (N) is derived as the initial high-frequency conversion efficiency η _ic . On the other _hand, P set ₍₁₎ when none _{to P The set} of (N) is not the same as the set power _{P sin} is set power closest to the set power _{P sin} of the smaller set power _{P The set} than the set power _{P sin} P _set (k-1) initial associated with high frequency conversion efficiency η _i (k-1), and, most set power _{P sin} set close to the power _{P the set} of the set power _{P sin} larger set power _{P the set} than The initial high-frequency conversion efficiency η _ic is derived by proportional distribution using the initial high-frequency conversion efficiency η _i (k) associated with (k).

In subsequent step ST703, it is determined whether or not the current high-frequency conversion efficiency η _m has decreased by a predetermined rate or more with respect to the initial high-frequency conversion efficiency η _ic . For example, it is determined whether or not the current high-frequency conversion efficiency η _m has decreased by 2% or more from the initial high-frequency conversion efficiency η _ic . The high frequency conversion efficiency of the magnetron 42 becomes smaller than the initial high frequency conversion efficiency as the magnetron 42 approaches the end of its life. If it is determined in step ST703 that the current high-frequency conversion efficiency η _m has not decreased by a predetermined ratio or more with respect to the initial high-frequency conversion efficiency η _ic , the flow chart shown in FIG. The procedure proceeds. On the other hand, if it is determined in step ST703 that the current high-frequency conversion efficiency η _m is lower than the initial high-frequency conversion efficiency η _ic by a predetermined ratio or more, it is determined that the magnetron 42 has reached the end of its life. In subsequent step ST9, an exchange request signal is output from the processor 110.

  In the process shown in FIG. 10, based on the comparison between the absolute value of the current anode voltage of the magnetron 42 as the current parameter indicating the current state of the magnetron 42 and the initial anode voltage of the magnetron 42 as the initial parameter, It is determined whether 42 has reached the end of its life.

Specifically, in the process shown in FIG. 10, first, in step ST711, the absolute value V _ic of the initial anode voltage is derived. In step ST711, if any one of the set power P _set stored in the memory 112, that is, P _set (1) to P _set (N) is the same as the set power P _sin , P _set (1) to The absolute value V _i (j) of the initial anode voltage associated with the set power P _set that is the same as the set power P _{sin in} P _set (N) is derived as the absolute value V _ic of the initial anode voltage. On the other _hand, P set ₍₁₎ when none _{to P The set} of (N) is not the same as the set power _{P sin} is set power closest to the set power _{P sin} of the smaller set power _{P The set} than the set power _{P sin} absolute value _V i of the initial anode voltage associated with the _{P set (k-1) (} k-1), and set the power closest to the set power _{P sin} of the larger set power _{P the set} than the set power _{P sin} The absolute value V _ic of the initial anode voltage is derived by proration using the absolute value V _i (k) of the initial anode voltage associated with P _set (k).

In subsequent step ST712, life determination is performed based on a comparison between the absolute value of the current anode voltage and the absolute value of the initial anode voltage. Specifically, the absolute value of the measured values V _m of the current anode voltage | Vm | whether is increasing more than a predetermined value with respect to the absolute value V _ics initial anode voltage is determined. For example, the absolute value of the measured values V _m of the current anode voltage | Vm | whether is increased 0.2kV or more relative to the absolute value V _ics initial anode voltage is determined. Vm | | absolute value of the measured values V _m of the current anode voltage here is the absolute value of the measured values V _m of the detected anode voltage in step ST2 immediately before the execution of step ST712 | Vm | is. Note that the absolute value of the anode voltage of the magnetron 42 becomes larger than the absolute value of the initial anode voltage as the magnetron 42 approaches its life. In step ST712, the absolute value of the measured values V _m of the current anode voltage | Vm | if it is determined not to be increased more than a predetermined value with respect to the absolute value V _ics initial anode voltage, in FIG. 6 In the flowchart shown, the procedure on the flow up to step ST2 proceeds. On the other hand, the absolute value of the measured values V _m of the current anode voltage | Vm | if it is determined to be increased by more than a predetermined value with respect to the absolute value V _ics initial anode voltage, to the magnetron 42 is life In step ST9, an exchange request signal is output from the processor 110.

  In the process shown in FIG. 11, the lifetime of the magnetron 42 is determined based on a comparison between the current anode current of the magnetron 42 as a current parameter indicating the current state of the magnetron 42 and the initial anode current of the magnetron 42 as an initial parameter. It is determined whether or not it has reached.

Specifically, in the process shown in FIG. 11, first, in step ST721, an initial anode current I _ic is derived. In step ST721, when any of the set power P _set stored in the memory 112, that is, any of P _set (1) to P _set (N) is the same as the set power P _sin , P _set (1) to An initial anode current I _i (j) associated with the same set power P _set (j) as the set power P _{sin in} P _set (N) is derived as the initial anode current I _ic . On the other _hand, P set ₍₁₎ when none _{to P The set} of (N) is not the same as the set power _{P sin} is set power closest to the set power _{P sin} of the smaller set power _{P The set} than the set power _{P sin} P _set (k-1) initial anode current associated with _I i (k-1), and, the set power _{P sin} set closest to the set power _{P sin} of the larger set power _{P the set} than the power _{P the set} ( The initial anode current I _ic is derived by proration using the initial anode current I _i (k) associated with k).

In subsequent step ST722, life determination is performed based on a comparison between the current anode current and the initial anode current. Specifically, whether the measured value I _m of the current of the anode current is increased by more than a predetermined value relative to the initial anode current I _ics is determined. For example, whether the measured value I _m of the current of the anode current is increased 0.1A or more to the initial anode current I _ics is determined. Here measurements I _m of the current of the anode current at is a measure I _m of the detected anode current in step ST2 immediately before the execution of step ST 722. Note that the anode current of the magnetron 42 becomes larger than the initial anode current as the life of the magnetron 42 approaches. In step ST 722, when the measured value I _m of the current of the anode current is determined not to be increased more than a predetermined value relative to the initial anode current I _ics is on the flow reaches step ST2 in the flowchart shown in FIG. 6 The procedure proceeds. On the other hand, when the measured value I _m of the current of the anode current is determined to be increased by more than a predetermined value relative to the initial anode current I _ics is determined that the magnetron 42 is led to life, followed by step In ST9, an exchange request signal is output from the processor 110.

  In the process shown in FIG. 12, the current peak frequency of the high frequency generated by the magnetron 42 is used as the current parameter indicating the current state of the magnetron 42, and the initial high frequency generated by the magnetron 42 is used as the initial parameter. The peak frequency is used. In the process shown in FIG. 12, it is determined whether the magnetron 42 has reached the end of its life based on a comparison between the current peak frequency and the initial peak frequency.

Specifically, in the process shown in FIG. 12, first, in step ST731, the initial peak frequency F _ic is derived. In step ST731, when any one of the set power P _set stored in the memory 112, that is, P _set (1) to P _set (N) is the same as the set power P _sin , P _set (1) to The initial peak frequency F _i (j) associated with the same set power P _set (j) as the set power P _{sin in} P _set (N) is derived as the initial peak frequency F _ic . On the other _hand, P set ₍₁₎ when none _{to P The set} of (N) is not the same as the set power _{P sin} is set power closest to the set power _{P sin} of the smaller set power _{P The set} than the set power _{P sin} P _set (k-1) in the associated initial peak frequency _F i (k-1), and, the set power _{P sin} set closest to the set power _{P sin} of the larger set power _{P the set} than the power _{P the set} ( The initial peak frequency F _ic is derived by proportional distribution using the initial peak frequency F _i (k) associated with k).

In continuing step ST732, lifetime determination based on the comparison with the present peak frequency and an initial peak frequency is performed. Specifically, whether the measured value F _m of the current peak frequency is lower than a predetermined value relative to the initial peak frequency F _ics (e.g., 2MHz) is determined. Here measurements F _m of the current peak frequency at is a measure F _m of the detected peak frequency in step ST2 immediately before the execution of step ST732. In step ST731, when the measured value F _m of the current peak frequency is determined not to have decreased by more than a predetermined value relative to the initial peak frequency F _ics is on the flow reaches step ST2 in the flowchart shown in FIG. 6 The procedure proceeds. On the other hand, if it is determined that the current peak frequency measurement value _Fm is lower than the initial peak frequency _Fic by a predetermined value or more, it is determined that the magnetron 42 has reached the end of its life, and the following steps In ST9, an exchange request signal is output from the processor 110.

  In this way, the method MT can be used to determine the current parameters of the magnetron 42, eg, current high frequency conversion efficiency, current anode current, current anode voltage, current peak frequency, obtained from measurements detected at the appropriate time. Since the lifetime of the magnetron 42 is determined using, for example, the magnetron 42 can be inspected with high accuracy.

  Refer to FIG. 6 again. In one embodiment, the method MT can predict the remaining length of time until the lifetime of the magnetron 42 by executing step ST8 by the processor 110. FIGS. 13 and 14 are flowcharts showing the processes available for step ST8 of the method shown in FIG. In the prediction of the remaining time length in step ST8, one or more of the plurality of processes shown in FIGS. 13 and 14 can be executed.

  In the process shown in FIG. 13, data in which the usage time length of the magnetron 42 is associated with the high-frequency conversion efficiency of the magnetron 42 is used. FIG. 15 is a diagram illustrating the relationship between the magnetron operating time length and the high-frequency conversion efficiency of the magnetron. As shown in FIG. 15, the high-frequency conversion efficiency of the magnetron 42 decreases as the usage time elapses. However, there may be some difference in the relationship between the operating time length of the magnetron 42 and the high-frequency conversion efficiency of the magnetron 42 due to machine differences. Therefore, data in which the use time length of the magnetron 42 averaged in consideration of the machine difference of the magnetron 42 and the high-frequency conversion efficiency of the magnetron 42 are associated with each other is stored in the memory 112 in advance. The data in which the usage time length of the magnetron 42 and the high-frequency conversion efficiency of the magnetron 42 are associated with each other may be tabular data or a function.

In the process shown in FIG. 13, in step ST801, the current usage time length of the magnetron 42 is obtained based on the current high-frequency conversion efficiency η _m . The current frequency conversion efficiency eta _m, it is possible to use the current frequency conversion efficiency eta _m obtained in step ST701. In step ST801, with reference to data in which the usage time length of the magnetron 42 is associated with the high frequency conversion efficiency of the magnetron 42, the usage time length corresponding to the current high frequency conversion efficiency η _m is obtained.

  In the subsequent step ST802, the remaining time length until the life of the magnetron 42 is obtained from the difference between the preset life time length of the magnetron and the current use time length obtained in step ST801.

In the process shown in FIG. 14, first, in Step ST811, the following equation (9) is used by using the current use time length t _c of the magnetron 42, the initial high-frequency conversion efficiency η _ic , and the current high-frequency conversion efficiency η _m. Based on the above, a constant A is obtained. The constant A is a constant that reflects variation in characteristics of the magnetron 42 to be inspected with respect to the average magnetron. Note that the current high-frequency conversion efficiency η _m obtained in step ST701 can be used as the current high-frequency conversion efficiency η _m . Further, the initial high-frequency conversion efficiency η _ic derived in step ST702 can be used as the initial high-frequency conversion efficiency η _ic . Further, the current use time length t _c can be obtained by accumulating the length of time that the magnetron 42 has been operated since the magnetron 42 was first operated and storing it in the memory 112.

In subsequent step ST812, using the predetermined high frequency conversion efficiency η _d at the lifetime of the magnetron 42, the constant A calculated in step S811, and the initial high frequency conversion efficiency η _ic , the following equation (10) is obtained. Based on this, the life time length t _d is calculated. The high-frequency conversion efficiency η _d at the lifetime of the magnetron 42 can be obtained by storing it in the memory 112 in advance.

In step ST813, the difference between the calculated life duration t _d and the current use time length t _c, the remaining length of time until the lifetime of the magnetron 42 is calculated. In the process shown in FIG. 14, the constant A reflecting the machine difference is calculated, and the remaining time is calculated based on the calculated constant A. Therefore, the remaining time length is obtained with higher accuracy.

  The remaining time length obtained by executing step ST8 based on the processing shown in FIG. 13 or FIG. 14 can be displayed on a display or the like. Thereby, the operator of the plasma processing apparatus 10 can grasp the remaining time length until the replacement time of the magnetron 42. After execution of this step ST8, the process of the method MT moves again to step ST2. Thereby, while the magnetron 42 is operated, the magnetron 42 can be inspected, and the replacement of the magnetron 42 can be performed in a timely manner.

  Hereinafter, a method for inspecting a magnetron according to another embodiment will be described. FIG. 16 is a flowchart illustrating a method for inspecting a magnetron according to another embodiment. A method MT2 shown in FIG. 16 is a method that can be used in the inspection of the magnetron 42 by the processor 110 of the plasma processing apparatus 10.

  Hereinafter, FIG. 17 will be referred to prior to the description of the method MT2 shown in FIG. FIG. 17 is a diagram showing temporal changes in the absolute value of the anode voltage of the magnetron, the anode current, and the high-frequency conversion efficiency. FIG. 17 shows changes over time in the absolute value of the anode voltage of the magnetron, the anode current, and the high-frequency conversion efficiency for each of the cases where the set power is 3000 W, 2000 W, and 1000 W. As shown in FIG. 17, the absolute value of the anode voltage of the magnetron, the anode current, and the high frequency conversion efficiency are shorter than the time length of the life but relatively long from the time when the magnetron starts generating the high frequency. When (for example, 900 seconds or more) elapses, the convergence value may be stabilized. For this reason, when a time length of several tens of seconds has elapsed from the time when the magnetron starts to generate a high frequency, a miscalculation with respect to the convergence value may not be able to obtain a minimum value. Such a tendency may be the same for the peak frequency of the traveling wave. Therefore, the method MT2 includes, as current parameters indicating the state of the magnetron 42, the high frequency conversion efficiency, the absolute value of the measured value of the anode voltage, the measured value of the anode current, and the measured value of the peak frequency of the traveling wave, respectively. A value reflecting an offset value with respect to the convergence value of is used.

  Also in this method MT2, the initial parameters are stored in the memory 112 as shown in FIG. The initial parameters may be provided as data representing initial specifications from the manufacturer of the magnetron 42 or the operator of the plasma processing apparatus 10 and stored in the memory 112. Alternatively, the initial parameter may be acquired from a measurement value for specifying the state of the magnetron 42 actually measured immediately after the magnetron 42 is incorporated into the plasma processing apparatus 10 and stored in the memory 112. However, in this case, the initial parameters are obtained in the same manner as the correction value of high-frequency conversion efficiency, the correction value of the absolute value of the anode voltage, the correction value of the anode current, and the correction value of the peak frequency of the traveling wave, which will be described later.

Prior to performing method MT2, magnetron 42 has not generated high frequencies. That is, the magnetron 42 stops its operation before the execution of the method MT2. Therefore, the operation signal MW _on is “0”. And in method MT2, step ST21 is first performed. In step ST21, the coefficient is initialized. The coefficient initialized in step ST21 includes the coefficient _CV when the process of FIG. 18 described later is included in the life determination, and when the process of FIG. 19 described later is included in the life determination. Includes a coefficient C _η and includes the coefficient C _I when the process of FIG. 20 described later is included in the life determination, and includes the coefficient C _I and includes the process of FIG. Includes coefficient C _F. The coefficient C _V , the coefficient C _η , the coefficient C _I , and the coefficient C _F are initialized to 0 in step ST21.

In subsequent step ST22, the processor 110 initializes the timer T _ON and the timer T _OFF . The timer _TON is a timer for measuring the time length of the period during which the magnetron 42 continuously generates high frequencies, and the timer T _OFF is the time of the stop period during which the magnetron 42 stops generating high frequencies. This is a timer for measuring the length.

In the subsequent step ST23, the timer T _OFF is counted up by the processor 110. Subsequent step ST24 is the same step as step ST2, and includes an operation signal MW _on , a measured value P _fm of traveling wave power, a measured value P _rm of reflected wave power, a measured value I _m of anode current, and a measured value of anode voltage. Detection of V _m and the peak frequency measurement F _m is performed by the processor 110.

The subsequent step ST25 is the same as step ST3. In step ST25, whether or not the measured value P _fm of the traveling wave power detected in step ST24 is greater than 0 and the operation signal MW _on is “1”. Is determined by the processor 110. That is, it is determined whether or not generation of high frequency by the magnetron 42 is started. In this step ST25, when it is determined that the traveling wave power measurement value P _fm is 0 or less and the operation signal MW _on is “0”, generation of high frequency by the magnetron 42 is not started. Therefore, the process from step ST23 is repeated. On the other hand, in step ST25, when it is determined that the measured value P _fm of the traveling wave power is greater than 0 or the operation signal MW _on is “1”, generation of high frequency by the magnetron 42 is started. Therefore, in the subsequent step ST26, the timer (T _ON ) is counted up by the processor 110.

Subsequent step ST27 is the same step as step ST5. In step ST27, the time when the measurement value of the latest step ST24 is detected has passed a predetermined time length or more from the start of generation of high frequency by the magnetron 42. A determination is made by the processor 110 as to whether it is a time. Specifically, when the count value of the timer (T _ON ) is smaller than a predetermined value, a time longer than a predetermined time length from the start of generation of high frequency by the magnetron 42 is detected at the time of detection of the latest measured value in step ST24. It is determined that the time has not passed. On the other hand, when the count value of the timer (T _ON ) is equal to or greater than a predetermined value, a time of a predetermined time length or more has elapsed since the start of generation of high frequency by the magnetron 42 at the time of detection of the latest measured value of step ST24. It is determined that it is a time. If it is determined in step ST27 that the most recent measurement value detected in step ST24 is not the time when a predetermined time length has elapsed since the start of generation of high frequency by the magnetron 42, the process from step ST24 is repeated. The process is repeated. On the other hand, if it is determined in step ST27 that the most recent measurement value detected in step ST24 is the time when a predetermined time length or more has elapsed since the start of generation of high frequency by the magnetron 42, the following step The process of ST28 is executed by the processor 110.

Step ST28 is the same as step ST6. In step ST28, the set power P _sin and the traveling wave power (measured value P _fm ) are substantially the same, and the reflected wave power (measured value P _rm ) is the same. It is determined whether or not it is substantially zero. For example, whether or not the difference between the measured value P _fm of the traveling wave power and the set power P _sin is equal to or smaller than a first predetermined value and the measured value P _rm of the reflected wave power is equal to or smaller than a second predetermined value. Is determined by the processor 110. In Step ST28, when it is determined that the set power P _sin and the traveling wave power (measured value P _fm ) are not substantially the same, or the reflected wave power (measured value P _rm ) is not substantially 0, the magnetron The operation of 42 is still considered unstable. Therefore, the process from step ST24 is executed again. On the other hand, when it is determined that the set power P _sin and the traveling wave power (measured value P _fm ) are substantially the same and the reflected wave power (measured value P _rm ) is substantially 0, in the subsequent step ST29 The lifetime of the magnetron 42 is determined by the processor 110.

  18 to 21 are flowcharts showing the processes available in step S29 of the method shown in FIG. Each of the plurality of processes shown in FIGS. 18 to 21 is performed on the magnetron obtained from the current measurement value that is the measurement value at the time when the determination criterion in step ST27 and the determination criterion in step ST28 described above, that is, the use condition is satisfied. Based on the comparison between the current parameter indicating the current state and the initial parameter indicating the initial state of the magnetron 42, it is determined whether or not the magnetron 42 has reached the end of its life. Hereinafter, the processes shown in FIGS. 18 to 21 will be described.

  In the process shown in FIG. 18, the correction value of the absolute value of the current anode voltage as the current parameter indicating the current state of the magnetron 42 is compared with the absolute value of the initial anode voltage of the magnetron 42 as the initial parameter. Based on this, it is determined whether or not the magnetron 42 has reached the end of its life.

Specifically, in the process shown in FIG. 18, first, in step ST2901, the absolute value V _ic of the initial anode voltage is derived as in step ST711.

In the subsequent step ST2902, the basic offset value VB _OFFSET (T _L ) is acquired using a predetermined fourth function f ₄ (t _A ). Reference is now made to FIG. FIG. 22 is a diagram showing the change with time of the absolute value of the anode voltage of the magnetron. FIG. 22 shows three magnetron Nos. Having the same configuration as the magnetron 42. 1-No. 3 shows the change over time in the absolute value of the anode voltage when a high frequency is continuously generated under a predetermined condition. Specifically, the change with time in the absolute value of the anode voltage shown in FIG. 22 is obtained when the set power P _set is 3000 (W).

  As shown in FIG. 1-No. The absolute values of the anode voltages of 3 are different from each other. However, magnetron no. 1-No. 3, the absolute value of the anode voltage decreases from the start of the generation of the high frequency, and almost the same tendency to reach the convergence value when a predetermined stable time length, for example, a time length of 900 seconds or more has elapsed. have. Magnetron no. 1-No. 3, the difference between the absolute value of the anode voltage at an arbitrary time and the convergence value of the absolute value of the anode voltage, that is, the offset value is substantially the same.

In the method MT2, the fourth function f ₄ (t _A ) is prepared in advance from the change over time of the anode voltage acquired under a predetermined condition, and the fourth function f ₄ (t _A ) is used. The predetermined fourth function f ₄ (t _A ) is an elapsed time length t from the start of a period in which the magnetron having the same configuration as the magnetron 42 continuously generates a high frequency under a predetermined condition to an arbitrary point in the period. _A is an absolute value of a difference between the anode voltage of the magnetron at the arbitrary time point and a convergence value of the anode voltage of the magnetron when the magnetron continuously generates a high frequency under the setting of the predetermined condition. This function determines the relationship with the basic offset value VB _OFFSET (t _A ). The predetermined condition is that the magnetron is stopped for a predetermined time, for example, 20 minutes before the generation of the high frequency, and the set power of the high-frequency traveling wave generated by the magnetron is the predetermined power. Including that.

The fourth function f ₄ (t _A ) is determined as, for example, the following expression.

f ₄ (t _A ) = VB _OFFSET (t _A ) = a 1 _V × t _A + b 1 When _V t _A is less than 300 seconds f ₄ (t _A ) = VB _OFFSET (t _A ) = a 2 _V × t _A + b 2 _V When t _A is not shorter than 300 seconds and shorter than 600 seconds When f ₄ (t _A ) = VB _OFFSET (t _A ) = a 3 _V × t _A + b 3 _V t _A is not shorter than 600 seconds and not longer than 900 seconds

In the above formula, a1 _V , b1 _V , a2 _V , b2 _V , a3 _V , and b3 _V are coefficients in the fourth function, and in one example, −0.1850, 95, −0.0837, 64, − 0.0235, 28. The fourth function f ₄ (t _A ) includes the elapsed time length t _A and the anode voltage and the anode voltage at any time point during the period in which the magnetron continuously generates high frequency under a predetermined condition. Any function may be used as long as it approximates the relationship with the absolute value of the difference from the convergence value.

In step ST2902, the elapsed time length T _L from the time when the magnetron 42 starts high frequency to the current time when the above-described use conditions are satisfied is set as the elapsed time length t _A in the fourth function f ₄ (t _A ). And the basic offset value VB _OFFSET (T _L ) is output as the output of the fourth function. The elapsed time length T _L is obtained from the count value of the timer (T _ON ).

  Reference is now made to FIG. FIG. 23 is a diagram showing the change with time of the absolute value of the anode voltage of the magnetron. FIG. 23 shows changes with time in the anode voltage when a magnetron having the same configuration as that of the magnetron 42 generates high-frequency traveling waves of three set powers (1000 W, 2000 W, 3000 W). As shown in FIG. 23, when the set power of the traveling wave is reduced, the variation amount of the anode voltage with respect to the convergence value is reduced with the change in anode voltage with time. That is, when the set power of the traveling wave decreases, the offset value with respect to the convergence value of the anode voltage at an arbitrary time point decreases. For example, when the set power is 3000 W, the maximum fluctuation amount of the anode voltage is 95 V, and when the set power is 2000 W, the maximum fluctuation amount of the anode voltage is 62 V and the set power is 1000 W. The maximum fluctuation amount of the anode voltage is 28V.

Thus, since the offset value for the convergence value of the anode voltage of the magnetron differs depending on the traveling wave power, in the subsequent step ST2903, the measured value P _fm of the traveling wave power at the current time point when the use condition is satisfied is determined. A coefficient B _V (P _fm ) representing the change rate of the offset value is acquired. For this reason, in the method MT2, the fifth function f ₅ (P _A ) is prepared in advance, and the fifth function f ₅ (P _A ) is used. This predetermined fifth function f _{5 (P A)} can consist of any forward power P _A, when the magnetron of the same configuration as the magnetron 42 is continuously generates a high-frequency settings under any forward power P _A Is a function that defines a relationship between a predetermined value as the maximum fluctuation amount of the anode voltage of the magnetron and a coefficient B _V (P _A ) representing a ratio of the basic offset value VB _OFFSET (t _A ) to a predetermined maximum value. is there. The maximum fluctuation amount of the anode voltage is defined as a difference between the maximum absolute value of the anode voltage and the convergence value of the anode voltage.

The fifth function f ₅ (P _A ) is determined as, for example, the following expression.

_{f 5 (P A) = B} V (P A) = 0 P if _A is less than or _{0kW 0.5kW f 5 (P A)} = B V (P A) = c V × P A -d V P A Is less than 0.5kW and less than 3.5kW

In the above equation, c _{V and} d _V are coefficients in the fifth function, respectively, and are 0.35 and 0.05 in an example. The values of these _{c V,} and the value of _{d V} is set power described above (3000W, 2000W, 1000W) and the maximum variation amount of the anode voltage (95V, 62V, 28V) of the basic offset value _{VB OFFSET (t A} ) Is obtained by deriving the fifth function f ₅ (P _A ) as a linear function approximating the relationship with the ratio to the predetermined maximum value (95 V). The fifth function f ₅ (P _A ) is an arbitrary traveling wave power P _A and an anode of the magnetron when the magnetron continuously generates a high frequency under the setting of the arbitrary traveling wave power P _A. Any function may be used as long as it approximates the relationship between the predetermined value as the maximum voltage fluctuation amount and the ratio of the basic offset value VB _OFFSET (t _A ) to the predetermined maximum value.

In step ST2903, the fifth function _f 5 _{(P A),} as a traveling wave power _{P A,} measured values _{P fm} of the current traveling wave power is inputted, the coefficient _B V as the output of the fifth function _{(P fm)} is Is output.

  Reference is now made to FIG. FIG. 24 is a diagram showing the relationship between the length of the magnetron stop period and the maximum fluctuation amount of the anode voltage of the magnetron during a period in which a high frequency is generated immediately after the stop period. The relationship shown in FIG. 24 is obtained by using a magnetron having the same configuration as the magnetron 42. In FIG. 24, the time length of the magnetron stop period is the time length of the period in which the magnetron stops generating high frequency, and the maximum fluctuation amount of the magnetron anode voltage is when the high frequency is generated immediately after the stop period. Is the maximum offset value with respect to the convergence value of the anode voltage of the magnetron.

As shown in FIG. 24, the maximum fluctuation amount of the anode voltage of the magnetron also depends on the time length of the magnetron stop period immediately before the period in which the magnetron generates a high frequency. Therefore, in the subsequent step ST2904, a coefficient D _V (T _S ) representing the change rate of the maximum fluctuation amount of the anode voltage according to the time length T _S of the stop period immediately before the start time of the high frequency of the magnetron 42 is acquired. For this reason, in the method MT2, the sixth function f6 (t _SA ) is prepared in advance, and the sixth function f ₆ (t _SA ) is used. The predetermined sixth function f6 (t _SA ) is an arbitrary stop time length t _{SA at} which the magnetron having the same configuration as the magnetron 42 stops the generation of the high frequency, and the magnetron stops the generation of the high frequency by a predetermined stop time length. The magnetron anode voltage when the high frequency is continuously generated immediately after the magnetron is stopped for an arbitrary stop time length with respect to the maximum fluctuation amount of the anode voltage of the magnetron when the high frequency is continuously generated immediately after It is a function that determines the relationship with the coefficient D _V (t _SA ) that represents the ratio of the maximum fluctuation amount.

The sixth function f ₆ (t _SA ) is determined as, for example, the following expression.

f ₆ (t _SA ) = D _V (t _SA ) = e _V × log ₁₀ (t _SA ) + f _V

In the above equation, e _V and f _V are coefficients in the sixth function, and are 0.19741 and 0.00201 in an example. The value of these e _V, and the value of f _V is the maximum change in the anode voltage when the set power shown in FIG. 24 is a 3000W, the anode voltage at a predetermined stop time length is 120 minutes The maximum variation is normalized as 1, and the relationship between the duration of the stop period and the normalized variation is approximated using a logarithmic function. Note that the sixth function f ₆ (t _SA ) has an arbitrary stop time length t _SA and the magnetron when the magnetron continuously generates a high frequency immediately after it has stopped generating a high frequency for a predetermined stop time length. It should be a function that can approximate the relationship between the maximum fluctuation amount of the anode voltage and the ratio of the maximum fluctuation amount of the anode voltage of the magnetron when the magnetron continuously generates a high frequency immediately after being stopped. For example, an arbitrary function may be used.

In step ST2904, the sixth function _f 6 _{(t SA),} as the time length _{t SA} outages, the magnetron 42 is the time length _{T S} period that has been stopped just before the beginning of the high frequency of occurrence is inputted, The coefficient D _V (T _S ) is output as the output of the sixth function. The time length T _S is obtained from the count value of the timer (T _OFF ).

In the following step ST2905, the basic offset value VB _OFFSET (T _L ), the coefficient B _V (P _fm ), the coefficient C _V , and the coefficient D _V (T _S ) are used in the equation (3), whereby the anode voltage of the magnetron 42 is obtained. Offset value V _OFFSET is obtained.

The coefficient C _V, when the first process shown in FIG. 18 immediately after the stop period of the magnetron 42 is executed is initialized coefficient C _V to step ST21, shown in FIG. 18 in the second and subsequent When the process is executed, the coefficient C _V is updated in step ST33 described later. The coefficient _CV is obtained in a period in which the magnetron 42 is generating a high frequency immediately before a stop period in which the magnetron 42 has stopped generating a high frequency immediately before the start of generation of a high frequency in the magnetron 42. This is obtained by dividing the offset value V _OFFSET of the anode voltage of the magnetron 42 by a predetermined maximum value (for example, 95 V) of the basic offset value VB _OFFSET (t _A ).

In the subsequent step ST2906, the current anode voltage measurement value V _m and offset value V _OFFSET of the magnetron 42 at the time when the use condition is satisfied are used in the equation (4) to calculate the absolute value of the current anode voltage. correction value _{V C} is required.

In the subsequent step ST2907, life determination is performed based on a comparison between the correction value V _C of the current absolute value of the anode voltage and the absolute value V _ic of the initial anode voltage. Specifically, it is determined whether or not the correction value V _C of the current absolute value of the anode voltage has increased by a predetermined value Th _V or more with respect to the absolute value V _ic of the initial anode voltage. Th _V is a positive numerical value. In step ST2907, when the correction value V _C of the absolute value of the current of the anode voltage is determined not to increase more than a predetermined value with respect to the absolute value V _ics initial anode voltage, in the flowchart shown in FIG. 16 The procedure on the flow through step ST30 proceeds. On the other hand, when the correction value V _C of the absolute value of the current of the anode voltage is determined to be increased by more than a predetermined value with respect to the absolute value V _ics initial anode voltage, which magnetron 42 is led to life In step ST31, a replacement request signal is output from the processor 110.

Step ST30 is the same as step ST8. In step ST30, the remaining time length until the lifetime of the magnetron 42 is predicted. In the subsequent step ST32, it is determined whether or not the operation signal MW _on is 0. If it is determined in step ST32 that the operation signal MW _on is not 0, that is, if it is determined that the magnetron 42 is continuously generating a high frequency, the processing from step ST24 is executed again. On the other hand, if it is determined in step ST32 that the operation signal MW _on is 0, that is, if it is determined that the magnetron 42 has stopped generating high frequency, the coefficient C is updated in the subsequent step ST33. . For example, when the process of FIG. 18 is included in the life determination, the coefficient _CV is updated. The coefficient C _V is obtained by dividing the offset value V _OFFSET obtained immediately before step ST33 by a predetermined maximum value (for example, 95 V) of the basic offset value VB _OFFSET (t _A ). Further, when the process of FIG. 19 described later is included in the life determination, the coefficient C _η is updated in step ST33, and when the process of FIG. 20 described later is included in the life determination, the coefficient C _η is updated. _{When I} is updated in step ST33 and the process of FIG. 21 described later is included in the life determination, the coefficient C _F is updated in step ST33.

  Hereinafter, the process illustrated in FIG. 19 will be described. In the process shown in FIG. 19, the magnetron 42 is based on the comparison between the correction value of the current high-frequency conversion efficiency as the current parameter indicating the current state of the magnetron 42 and the initial high-frequency conversion efficiency of the magnetron 42 as the initial parameter. It is determined whether or not the battery has reached the end of its life.

Specifically, in the processing shown in FIG. 19, first, in step ST2911, likewise the current frequency conversion efficiency eta _m is calculated in step ST701. In subsequent step ST2912, the initial high-frequency conversion efficiency η _ic is acquired in the same manner as in step ST702.

In subsequent step ST2913, basic offset value ηB _OFFSET (T _L ) is acquired using predetermined first function f ₁ (t _A ). In the method MT2, the first function f ₁ (t _A ) is prepared in advance from the change over time in the high-frequency conversion efficiency acquired when the magnetron having the same configuration as the magnetron 42 generates a high frequency under a predetermined condition. The first function f ₁ (t _A ) is used. The predetermined first function f ₁ (t _A ) is an elapsed time from the start of a period in which a magnetron having the same configuration as the magnetron 42 continuously generates a high frequency under a predetermined condition to an arbitrary point in the period. The absolute value of the difference between the length t _A and the high-frequency conversion efficiency of the magnetron at the arbitrary time and the convergence value of the high-frequency conversion efficiency of the magnetron when the magnetron continuously generates a high frequency under the predetermined condition Is a function that determines the relationship with the basic offset value ηB _OFFSET (t _A ). The predetermined condition is that the magnetron is stopped for a predetermined time, for example, 20 minutes before the generation of the high frequency, and the set power of the high-frequency traveling wave generated by the magnetron is the predetermined power. Including that.

The first function f ₁ (t _A ) is determined as, for example, the following expression.

f ₁ (t _A ) = ηB _OFFSET (t _A ) = a 1 _η × t _A + b 1 _η t _A when _A is less than 300 seconds f ₁ (t _A ) = ηB _OFFSET (t _A ) = a 2 _η × t _A + b 2 _η When t _A is 300 seconds or more and less than 600 seconds: f ₁ (t _A ) = ηB _OFFSET (t _A ) = a 3 _η × t _A + b3 _η t _A is 600 seconds or more and 900 seconds or less

In the above formula, a1 _η , b1 _η , a2 _η , b2 _η , a3 _η , b3 _η are coefficients in the first function. The first function f ₁ (t _A ) includes the elapsed time length t _A at the arbitrary time point and the high frequency at the arbitrary time point during the period in which the magnetron continuously generates high frequency under the predetermined condition. Any function may be used as long as it approximates the relationship between the conversion efficiency and the absolute value of the difference between the convergence values of the high-frequency conversion efficiencies.

In Step ST2913, the elapsed time length T _L from the time when the magnetron 42 starts high frequency to the current time when the above-described use conditions are satisfied is set as the elapsed time length t _A in the first function f ₁ (t _A ). And the basic offset value ηB _OFFSET (T _L ) is output as the output of the first function. The elapsed time length T _L is obtained from the count value of the timer (T _ON ).

In the subsequent step ST2914, a coefficient B _η (P _fm ) representing the rate of change of the offset value of the high-frequency conversion efficiency according to the measured value P _fm of the traveling wave power at the current time when the use condition is satisfied is acquired. . For this reason, in the method MT2, the second function f ₂ (P _A ) is prepared in advance, and the second function f ₂ (P _A ) is used. This predetermined second function f ₂ (P _A ) is obtained when an arbitrary traveling wave power P _A and a magnetron having the same configuration as the magnetron 42 continuously generate a high frequency under the setting of the arbitrary traveling wave power. _A function that defines the relationship between a predetermined value as the maximum fluctuation amount of the high-frequency conversion efficiency of the magnetron and a coefficient B _η (P _A ) that represents a ratio of the basic offset value ηB _OFFSET (t _A ) to a predetermined maximum value. is there. Note that the maximum fluctuation amount of the high-frequency conversion efficiency is defined as the difference between the maximum value of the high-frequency conversion efficiency and the convergence value of the high-frequency conversion efficiency.

The second function f ₂ (P _A ) is determined as, for example, the following expression.

_{f 2 (P A) = B} η (P A) = 0 P if _A is less than or _{0kW 0.5kW f 2 (P A)} = B η (P A) = c η × P A -d η P A Is less than 0.5kW and less than 3.5kW

In the above formula, c _η and d _η are coefficients in the second function. It should be noted that the second function f ₂ (P _A ) has an arbitrary traveling wave power P _A and that of the magnetron during a period in which the magnetron continuously generates a high frequency under the setting of the arbitrary traveling wave power P _A. Any function may be used as long as it approximates the relationship between the predetermined value as the maximum fluctuation amount of the high-frequency conversion efficiency and the ratio of the basic offset value ηB _OFFSET (t _A ) to the predetermined maximum value. .

In step ST2914, the second function _f 2 _{(P A),} as a traveling wave power _{P A,} is inputted measured value _{P fm} of the current traveling wave power, coefficient _B η _{(P fm)} as an output of the second function Is output.

In the subsequent step ST2915, a coefficient D _η (T _S ) representing the rate of change of the maximum fluctuation amount of the high frequency conversion efficiency according to the time length T _S of the stop period immediately before the start time of the high frequency of the magnetron 42 is acquired. For this reason, in the method MT2, the third function f ₃ (t _SA ) is prepared in advance, and the third function f ₃ (t _SA ) is used. The predetermined third function f ₃ (t _SA ) includes an arbitrary stop time length t _{SA at} which the magnetron having the same configuration as the magnetron 42 stops generating high frequency, and the magnetron generates high frequency at a predetermined stop time length, For the maximum fluctuation amount of the high frequency conversion efficiency of the magnetron when the high frequency is continuously generated immediately after the stop, the magnetron of the magnetron when the high frequency is continuously generated immediately after the magnetron is arbitrarily stopped. It is a function that defines the relationship with the coefficient Dη (t _SA ) that represents the ratio of the maximum fluctuation amount of the high-frequency conversion efficiency.

The third function f ₃ (t _SA ) is determined, for example, as follows:

f ₃ (t _SA ) = D _η (t _SA ) = e _η × log ₁₀ (t _SA ) + f _η

In the above equation, e _η and f _η are coefficients in the third function. Note that the third function f ₃ (t _SA ) has an arbitrary stop time length t _SA and the magnetron when the magnetron continuously generates a high frequency immediately after it has stopped generating a high frequency for a predetermined stop time length. A function that can approximate the relationship between the maximum fluctuation amount of the high frequency conversion efficiency and the ratio of the maximum fluctuation amount of the high frequency conversion efficiency of the magnetron when the magnetron continuously generates a high frequency immediately after the magnetron is stopped. Any function may be used.

In Step ST2915, the time length T _{S of the} period in which the magnetron 42 is stopped immediately before the start of the generation of the high frequency is input to the third function f ₃ (t _SA ) as the time length t _SA of the stop period. The coefficient D _η (T _S ) is output as the output of the third function. The time length T _S is obtained from the count value of the timer (T _OFF ).

In the subsequent step ST2916, the basic offset value ηB _OFFSET (T _L ), the coefficient B _η (P _fm ), the coefficient C _η , and the coefficient D _η (T _S ) are used in the equation (1), thereby high-frequency conversion of the magnetron 42. An efficiency offset value η _OFFSET is determined.

Incidentally, the coefficient C _eta, when the first process shown in FIG. 19 immediately after the stop period of the magnetron 42 is performed, a coefficient C _eta initialized to step ST21, shown in FIG. 19 in the second and subsequent When the process is executed, the coefficient C _η updated in step ST33. The coefficient C _η is obtained in a period in which the magnetron 42 is generating a high frequency immediately before a stop period in which the magnetron 42 has stopped generating a high frequency immediately before the start of generation of a high frequency in the magnetron 42. It is obtained by dividing the offset value η _OFFSET of the high frequency conversion efficiency of the magnetron 42 by a predetermined maximum value of the basic offset value ηB _OFFSET (t _A ).

In subsequent step ST2917, the current high frequency conversion efficiency η _m and offset value η _OFFSET of the magnetron 42 at the time when the use condition is satisfied are used in the equation (2) to correct the absolute value of the current high frequency conversion efficiency. The value η _C is determined.

In the subsequent step ST2918, life determination is performed based on a comparison between the current high-frequency conversion efficiency correction value η _C and the initial high-frequency conversion efficiency η _ic . Specifically, it is determined whether or not the current correction value η _C of the high-frequency conversion efficiency has decreased by a predetermined ratio (−Th _η ) or more with respect to the initial high-frequency conversion efficiency η _ic . Th _η is a positive ratio (%). When it is determined in step ST2918 that the current high-frequency conversion efficiency correction value η _C has not decreased by a predetermined ratio or more with respect to the initial high-frequency conversion efficiency η _ic , the process goes through step ST30 in the flowchart shown in FIG. The process on the flow to proceed. On the other hand, when it is determined that the current high-frequency conversion efficiency correction value η _C is lower than a predetermined ratio with respect to the initial high-frequency conversion efficiency η _ic , it is determined that the magnetron 42 has reached the end of its life, In the subsequent step ST31, an exchange request signal is output from the processor 110.

If the process of FIG. 19 is included in the life determination, the coefficient C _η is updated in step ST33. The coefficient C _η is obtained by dividing the offset value η _OFFSET obtained immediately before step ST33 by a predetermined maximum value of the basic offset value ηB _OFFSET (t _A ).

  Hereinafter, the process illustrated in FIG. 20 will be described. In the process shown in FIG. 20, the lifetime of the magnetron 42 is determined based on the comparison between the correction value of the current anode current as the current parameter indicating the current state of the magnetron 42 and the initial anode current of the magnetron 42 as the initial parameter. It is determined whether or not it has reached.

Specifically, in the process shown in FIG. 20, first, in step ST2921, the initial anode current I _ic is acquired as in step ST721.

In subsequent Step ST2922, the basic offset value IB _OFFSET (T _L ) is acquired using a predetermined seventh function f ₇ (t _A ). In the method MT2, a seventh function f ₇ (t _A ) is prepared in advance from the change over time in the anode current acquired when the magnetron having the same configuration as the magnetron 42 generates a high frequency under a predetermined condition. The seventh function f ₇ (t _A ) is used. The predetermined seventh function f ₇ (t _A ) is an elapsed time length t _A from the start of a period in which the same configuration as the magnetron 42 generates a high frequency under a predetermined predetermined condition to an arbitrary point in the period, Basic offset value IB _OFFSET which is an absolute value of a difference between the magnetron anode current at the arbitrary time point and the convergence value of the magnetron anode current when the magnetron continuously generates a high frequency under the predetermined condition It is a function that determines the relationship with (t _A ). The predetermined condition is that the magnetron is stopped for a predetermined time, for example, 20 minutes before the generation of the high frequency, and the set power of the high-frequency traveling wave generated by the magnetron is the predetermined power. Including that.

For example, the seventh function f ₇ (t _A ) is specified as in the following equation.

When f ₇ (t _A ) = IB _OFFSET (t _A ) = a 1 _I × t _A + b 1 _I t _A is less than 300 seconds f ₇ (t _A ) = IB _OFFSET (t _A ) = a 2 _I × t _A + b 2 _I If t _a is less than 300 seconds or longer 600 seconds _{f 7 (t a) = IB} OFFSET (t a) = a3 I × t a + b3 I t when _a is less than 900 seconds 600 seconds

In the above formula, a1 _I , b1 _I , a2 _I , b2 _I , a3 _I , and b3 _I are coefficients in the seventh function. The seventh function f ₇ (t _A ) includes the elapsed time length t _A at the arbitrary time point and the anode at the arbitrary time point during the period in which the magnetron continuously generates a high frequency under the predetermined condition. Any function that approximates the relationship between the current and the absolute value of the difference between the convergence values of the anode currents may be used.

In Step ST2922, in the seventh function f ₇ (t _A ), as the elapsed time length t _A , the elapsed time length T _L from the time when the magnetron 42 starts high frequency to the current time when the use conditions described above are satisfied. And the basic offset value IB _OFFSET (T _L ) is output as the output of the seventh function. The elapsed time length T _L is obtained from the count value of the timer (T _ON ).

In the subsequent step ST2923, a coefficient B _I (P _fm ) representing the rate of change of the offset value of the anode current corresponding to the measured value P _fm of the traveling wave power at the current time when the use condition is satisfied is acquired. For this reason, in the method MT2, the eighth function f ₈ (P _A ) is prepared in advance, and the eighth function f ₈ (P _A ) is used. The predetermined eighth function f ₈ (P _A ) is obtained when an arbitrary traveling wave power P _A and a magnetron having the same configuration as the magnetron 42 continuously generate a high frequency under the setting of the arbitrary traveling wave power. It is a function that determines the relationship between a predetermined value as the maximum fluctuation amount of the anode current of the magnetron and a coefficient B _I (P _A ) that represents a ratio of the basic offset value IB _OFFSET (t _A ) to a predetermined maximum value. . The maximum fluctuation amount of the anode current is defined as the difference between the minimum value of the anode current and the convergence value of the anode current.

The eighth function f ₈ (P _A ) is determined as, for example, the following expression.

_{f 8 (P A) = B} I (P A) = 0 if _{P A} is less than 0.5kW than _{0kW f 8 (P A) =} B I (P A) = c I × P A -d I P A Is less than 0.5kW and less than 3.5kW

In the above formula, c _I and d _I are coefficients in the eighth function. It should be noted that the eighth function f ₈ (P _A ) is an arbitrary traveling wave power P _A and a value of the magnetron during a period in which the magnetron continuously generates a high frequency under the setting of the arbitrary traveling wave power P _A. Any function may be used as long as the function approximates the relationship between the predetermined value as the maximum fluctuation amount of the anode current and the ratio of the basic offset value IB _OFFSET (t _A ) to the predetermined maximum value.

In step ST2923, the eighth function _f 8 _{(P A),} as a traveling wave power _{P A,} measured values _{P fm} of the current traveling wave power is inputted, the coefficient _B I as the output of the eighth function _{(P fm)} is Is output.

In the subsequent step ST2924, a coefficient D _I (T _S ) representing the change rate of the maximum fluctuation amount of the anode current according to the time length T _S of the stop period immediately before the start time of the high frequency of the magnetron 42 is acquired. For this reason, in the method MT2, the ninth function f ₉ (t _SA ) is prepared in advance, and the ninth function f ₉ (t _SA ) is used. The predetermined ninth function f ₉ (t _SA ) is an arbitrary stop time length t _{SA at} which the magnetron having the same configuration as the magnetron 42 stops generating high frequency, and the magnetron stops generating high frequency for a predetermined stop time length, With respect to the maximum fluctuation amount of the anode current of the magnetron when the high frequency is continuously generated immediately after the stop, the magnetron of the magnetron when the high frequency is continuously generated immediately after the magnetron is stopped. It is a function that defines the relationship of the coefficient D _I (t _SA ) that represents the ratio of the maximum fluctuation amount of the anode current.

The ninth function f ₈ (t _SA ) is determined as, for example, the following expression.

f ₉ (t _SA ) = D _I (t _SA ) = e _I × log ₁₀ (t _SA ) + f _I

In the above equation, e _I and f _I are coefficients in the ninth function. Note that the ninth function f ₉ (t _SA ) has an arbitrary stop time length t _SA and the magnetron when the magnetron continuously generates a high frequency immediately after it stops generating a high frequency for a predetermined stop time length. If the function can approximate the relationship between the fluctuation amount of the anode current and the ratio of the fluctuation amount of the anode current of the magnetron when the magnetron continuously generates a high frequency immediately after stopping, with respect to the fluctuation amount of the anode current, Any function may be used.

In step ST2924, the ninth function _f 9 _{(t SA),} as the time length _{t SA} outages, the magnetron 42 is the time length _{T S} period that has been stopped just before the beginning of the high frequency of occurrence is inputted, The coefficient D _I (T _S ) is output as the output of the ninth function. The time length T _S is obtained from the count value of the timer (T _OFF ).

In the following step ST2925, the basic offset value IB _OFFSET (T _L ), the coefficient B _I (P _fm ), the coefficient C _I , and the coefficient D _I (T _S ) are used in the equation (5), whereby the anode current of the magnetron 42 is determined. Offset value I _OFFSET is obtained.

The coefficient C _I, when the first process shown in FIG. 20 immediately after the stop period of the magnetron 42 is executed is initialized coefficients C _I in step ST21, shown in FIG. 20 in the second and subsequent when the processing is executed, a coefficient C _I, which is updated in step ST33. The coefficients C _I is obtained in the period in which the magnetron 42 has occurred the frequency immediately before the stop period in which the magnetron 42 to immediately before the start of the high-frequency generator of the magnetron 42 has stopped generation of high frequency It is obtained by dividing the offset value I _OFFSET of the anode current of the magnetron 42 by a predetermined maximum value of the basic offset value IB _OFFSET (t _A ).

In step ST2926, by using the measured value _{I m} and the offset value _{I OFFSET} current anode current of the magnetron 42 at the time when the use condition is satisfied in equation (6), the correction value I of the current of the anode current _C is required.

In step ST2927, based on a comparison between the corrected value _{I C} and an initial anode current _{I ics} current anode current, the life determination is made. Specifically, it is determined whether or not the current anode current correction value I _C has increased by a predetermined value (Th _I ) or more with respect to the initial anode current I _ic . Th _I is a positive numerical value. If it is determined in step ST2927 that the current anode current correction value I _C has not increased by a predetermined value or more with respect to the initial anode current I _ic , the flow via step ST30 in the flowchart shown in FIG. The above procedure proceeds. On the other hand, if it is determined that the current anode current correction value I _C has increased by a predetermined value or more with respect to the initial anode current I _ic , it is determined that the magnetron 42 has reached the end of its life, and the following step In ST31, an exchange request signal is output from the processor 110.

In the case where the processing of FIG. 20 is included in the lifetime determination, in step ST33, the coefficient C _I is updated. The coefficient C _I is obtained by dividing the offset value I _OFFSET obtained immediately before step ST33 by a predetermined maximum value of the basic offset value IB _OFFSET (t _A ).

  Hereinafter, the process shown in FIG. 21 will be described. In the process shown in FIG. 21, the correction value of the current traveling wave peak frequency as a current parameter indicating the current state of the magnetron 42 is compared with the initial traveling wave peak frequency of the magnetron 42 as an initial parameter. Based on this, it is determined whether or not the magnetron 42 has reached the end of its life.

Specifically, in the processing shown in FIG. 21, first, at ST2931, as in step ST731, the initial peak frequency _{F ics} is obtained.

In subsequent Step ST2932, a basic offset value FB _OFFSET (T _L ) is acquired using a predetermined tenth function f ₁₀ (t _A ). In the method MT2, a tenth function f ₁₀ (t _A ) is prepared in advance from a change with time of a peak frequency acquired when a magnetron having the same configuration as the magnetron 42 generates a high frequency under a predetermined condition. The tenth function f ₁₀ (t _A ) is used. The predetermined tenth function f ₁₀ (t _A ) is an elapsed time length t from the start of a period in which the magnetron having the same configuration as the magnetron 42 continuously generates a high frequency under a predetermined condition to an arbitrary point in the period. _A , convergence of the peak frequency of the traveling wave of the magnetron at the arbitrary time point and the peak frequency of the traveling wave of the magnetron when the magnetron continuously generates a high frequency under a predetermined traveling wave power setting condition It is a function that determines the relationship with the basic offset value FB _OFFSET (t _A ), which is the absolute value of the difference from the value. The predetermined condition is that the magnetron is stopped for a predetermined time, for example, 20 minutes before the generation of the high frequency, and the set power of the high-frequency traveling wave generated by the magnetron is the predetermined power. Including that.

The tenth function f ₁₀ (t _A ) is determined as, for example, the following expression.

f ₁₀ (t _A ) = FB _OFFSET (t _A ) = a 1 _F × t _A + b 1 When _F t _A is less than 300 seconds f ₁₀ (t _A ) = FB _OFFSET (t _A ) = a 2 _F × t _A + b 2 _F When t _A is 300 seconds or more and less than 600 seconds: f ₁₀ (t _A ) = FB _OFFSET (t _A ) = a 3 _F × t _A + b 3 _F t _A is 600 seconds or more and 900 seconds or less

In the above formula, a1 _F , b1 _F , a2 _F , b2 _F , a3 _F , and b3 _F are coefficients in the tenth function. Note that the tenth function f ₁₀ (t _A ) is the elapsed time length t _A at the arbitrary time point and the arbitrary time point during the period in which the magnetron continuously generates high frequencies under the predetermined condition. Any function may be used as long as it approximates the relationship between the peak frequency and the absolute value of the difference between the peak frequencies.

In Step ST2932, the elapsed time length T _L from the time when the magnetron 42 starts high frequency to the current time when the above-described use conditions are satisfied is set as the elapsed time length t _A in the tenth function f ₁₀ (t _A ). And the basic offset value FB _OFFSET (T _L ) is output as the output of the tenth function. The elapsed time length T _L is obtained from the count value of the timer (T _ON ).

In subsequent step ST2933, coefficient B _F (P _fm ) representing the rate of change of the offset value of the peak frequency in accordance with measured value P _fm of the traveling wave power at the current time when the use condition is satisfied is acquired. For this reason, in the method MT2, the eleventh function f ₁₁ (P _A ) is prepared in advance, and the eleventh function f ₁₁ (P _A ) is used. The predetermined eleventh function f ₁₁ (P _A ) is obtained when an arbitrary traveling wave power P _A and a magnetron having the same configuration as the magnetron 42 continuously generate a high frequency under the setting of the arbitrary traveling wave power P _{A. A} function that determines the relationship between a predetermined value as the maximum fluctuation amount of the peak frequency of the traveling wave and a coefficient B _F (P _A ) that represents a ratio of the basic offset value FB _OFFSET (t _A ) to a predetermined maximum value. is there. The maximum fluctuation amount of the peak frequency is defined as the difference between the maximum value of the peak frequency and the convergence value of the peak frequency.

The eleventh function f ₁₁ (P _A ) is determined, for example, as in the following equation.

_{f 11 (P A) = B} F (P A) = 0 P if _A is less than or _{0kW 0.5kW f 11 (P A)} = B F (P A) = c F × P A -d F P A Is less than 0.5kW and less than 3.5kW

In the above equation, c _F and d _F are coefficients in the eleventh function. The eleventh function f ₁₁ (P _A ) has an arbitrary traveling wave power P _A and a peak frequency during a period in which the magnetron continuously generates a high frequency under the setting of the arbitrary traveling wave power P _A. Any function may be used as long as it approximates the relationship between the predetermined value as the maximum fluctuation amount and the ratio of the basic offset value FB _OFFSET (t _A ) to the predetermined maximum value.

In step ST2933, the eleventh function _f 11 _{(P A),} as a traveling wave power _{P A,} measured values _{P fm} of the current traveling wave power is inputted, the coefficient _B F _{(P fm)} as the output of the 11 functions Is output.

In the subsequent step ST2934, a coefficient D _F (T _S ) representing the change rate of the maximum fluctuation amount of the peak frequency according to the time length T _S of the stop period immediately before the start time of the high frequency of the magnetron 42 is acquired. For this reason, in the method MT2, the twelfth function f ₁₂ (t _SA ) is prepared in advance, and the twelfth function f ₁₂ (t _SA ) is used. The predetermined twelfth function f ₁₂ (t _SA ) includes an arbitrary stop time length t _{SA at} which the magnetron having the same configuration as the magnetron 42 stops generating high frequency, and the magnetron generates high frequency at a predetermined stop time length, For the maximum fluctuation amount of the peak frequency of the traveling wave when the high frequency is continuously generated immediately after the stop, the traveling time of the traveling wave when the magnetron continuously generates the high frequency immediately after the magnetron is stopped. It is a function that determines the relationship of the coefficient D _F (t _SA ) that represents the ratio of the maximum fluctuation amount of the peak frequency.

The twelfth function f ₁₂ (t _SA ) is determined as, for example, the following expression.

f ₁₂ (t _SA ) = D _F (t _SA ) = e _F × log ₁₀ (t _SA ) + f _F

In the above equation, e _F and f _F are coefficients in the twelfth function. The twelfth function f ₁₂ (t _SA ) has an arbitrary stop time length t _SA and a peak frequency when the magnetron continuously generates a high frequency immediately after it has stopped generating a high frequency for a predetermined stop time length. Any function can be used as long as it can approximate the relationship between the maximum fluctuation amount and the ratio of the maximum fluctuation amount of the peak frequency when the magnetron continuously generates a high frequency immediately after stopping. There may be.

In Step ST2934, the time length T _{S of the} period in which the magnetron 42 is stopped immediately before the start of the generation of the high frequency is input to the twelfth function f ₁₂ (t _SA ) as the time length t _SA of the stop period. A coefficient D _F (T _S ) is output as the output of the twelfth function. The time length T _S is obtained from the count value of the timer (T _OFF ).

In the following step ST2935, the peak frequency of the magnetron 42 is obtained by using the basic offset value FB _OFFSET (T _L ), the coefficient B _F (P _fm ), the coefficient C _F , and the coefficient D _F (T _S ) in the equation (7). Offset value F _OFFSET is obtained.

The coefficient C _F, when the first process shown in FIG. 21 immediately after the stop period of the magnetron 42 is performed, a coefficient C _F initialized to step ST21, shown in FIG. 21 in the second and subsequent When the process is executed, the coefficient C _F is updated in step ST33. The coefficient C _F is obtained in a period in which the magnetron 42 is generating a high frequency immediately before a stop period in which the magnetron 42 has stopped generating a high frequency immediately before the start of generation of a high frequency in the magnetron 42. It is obtained by dividing the offset value F _OFFSET of the peak frequency of the magnetron 42 by a predetermined maximum value of the basic offset value FB _OFFSET (t _A ).

In step ST2936, by using a current measurement value _{F m} and the offset value _{F OFFSET} peak frequency of the magnetron 42 at the time when the use condition is satisfied in equation (8), the correction value F of the current peak frequency _C is required.

In step ST2937, based on a comparison of the correction value _{F C} and an initial peak frequency _{F ics} of the current peak frequency, the lifetime determination is performed. Specifically, whether or not the correction value F _C of the current peak frequency is lower than a predetermined value relative to the initial peak frequency F _ics is determined. Note that Th _F in FIG. 21 is a negative value. In step ST2937, when the correction value F _C of the current peak frequency is determined not to have decreased by more than a predetermined value relative to the initial peak frequency F _ics is via a step ST30 in the flowchart shown in FIG. 16 Flow The above procedure proceeds. On the other hand, when the correction value F _C of the current peak frequency is determined to be lowered more than a predetermined value relative to the initial peak frequency F _ics it is determined that the magnetron 42 is led to life, followed by step In ST31, an exchange request signal is output from the processor 110.

When the process of FIG. 21 is included in the life determination, the coefficient C _F is updated in step ST33. The coefficient C _F is obtained by dividing the offset value F _OFFSET obtained immediately before step ST33 by a predetermined maximum value of the basic offset value FB _OFFSET (t _A ).

In the method MT2 using the life determination process shown in FIGS. 18 to 21 described above, the correction value of the current parameter reflecting the offset value is acquired. Therefore, in the method MT2, the current parameters of the magnetron with a small error from the convergence value can be obtained. As a result, the numerical values of the determination criteria such as Th _V , Th _η , Th _I , and Th _F described above can be set to values having a small absolute value. Therefore, it is possible to determine the life of the magnetron with higher accuracy.

  In the method MT2, the life determination process in FIGS. 18 to 21 may be replaced with the life determination process in FIGS. 10, 9, 11, and 12, respectively. Further, it is desirable that the number of significant digits of numerical values such as measurement values used in the method MT and the method MT2 is three digits or more. By using such a numerical value of effective digits, the accuracy of life determination is further improved.

  Although various embodiments have been described above, various modifications can be made without being limited to the above-described embodiments. For example, the configurations of the plasma processing apparatus 10, the microwave generator 41a, and the control circuit 100 illustrated in FIGS. 1 to 5 are merely examples, and the method MT and the method MT2 are incorporated in an arbitrary plasma processing apparatus. It can be used for magnetron inspection.

  DESCRIPTION OF SYMBOLS 10 ... Plasma processing apparatus, 12 ... Processing container, 13 ... Gas supply part, 19 ... Plasma generation mechanism, 35 ... Rectangular waveguide, 41a ... Microwave generator, 42 ... Magnetron, 43 ... High voltage power supply, 44 ... Filament power supply 46a ... cathode electrode, 46b ... anode electrode, 50 ... load, 51 ... 4E tuner, 54 ... directional coupler, 90 ... detector, 92 ... detector, 94 ... frequency detector, 100 ... control circuit, 110 ... Processor, 112 ... Memory, 120 ... Voltage monitor, 122 ... Current monitor, 130 ... External computer device.

Claims (11)

A method for inspecting a magnetron,
Causing the magnetron to start generating a high frequency based on the set power;
Detecting one or more measurements to identify the state of the magnetron;
Determining whether a time of a predetermined time length or more has elapsed since the start of generation of the high frequency by the magnetron;
Determining whether a difference between a traveling wave power based on the high frequency generated by the magnetron and the set power is equal to or less than a first predetermined value;
Determining whether the power of the reflected wave output from the directional coupler provided between the magnetron and the load is equal to or lower than a second predetermined value;
A time equal to or longer than the predetermined time has elapsed from the start time, a difference between the power of the traveling wave and the set power is equal to or less than the first predetermined value, and the power of the reflected wave is the second A current parameter indicating a current state of the magnetron obtained from the one or more measured values at a time point when a use condition equal to or less than a predetermined value is satisfied, and an initial state of the magnetron corresponding to the current parameter Determining the lifetime of the magnetron based on a comparison with the initial parameters shown;
Including methods. The current parameter includes the current high frequency conversion efficiency of the magnetron;
The high frequency conversion efficiency is a value obtained by dividing the traveling wave power contained in the one or more measured values by the input power to the magnetron,
In the step of determining the lifetime of the magnetron, when the current high-frequency conversion efficiency is lower than a predetermined ratio with respect to the initial high-frequency conversion efficiency of the magnetron included in the initial parameter, Detect life,
The method of claim 1. By inputting an elapsed time length _TL from the start time point to the time point when the use condition is satisfied to a predetermined first function, a first basic offset value that is an output of the predetermined first function ηB _OFFSET (T _L ) is obtained, and the predetermined first function is an arbitrary value in the period from the start of a period in which the magnetron continuously generates a high frequency under a predetermined traveling wave power setting. Elapsed time length t _A to the time point, high-frequency conversion efficiency of the magnetron at the arbitrary time point, and high-frequency conversion of the magnetron when the magnetron continuously generates a high frequency under the predetermined traveling wave power setting Defining a relationship with a first basic offset value ηB _OFFSET (t _A ) that is an absolute value of a difference from the efficiency convergence value;
The measured value P _fm of the traveling wave power at the time when the use condition is satisfied is input to a predetermined second function, whereby a coefficient B _η (P _fm) that is an output of the predetermined second function is input. ) is a step of acquiring, said predetermined second function, and any forward power P _a, of the magnetron when the magnetron is continuously generating a high frequency under setting said given traveling wave power Defining a relationship between a predetermined value as a maximum fluctuation amount of the high-frequency conversion efficiency and a coefficient B _η (P _A ) representing a ratio of the first basic offset value ηB _OFFSET (t _A ) to a predetermined maximum value; The step;
The offset value of the high-frequency conversion efficiency of the magnetron obtained in the period in which the magnetron is generating high frequency immediately before the stop period in which the magnetron has stopped generating high-frequency immediately before the start time is the first value. Obtaining a coefficient C _η by dividing by the predetermined maximum value of the basic offset value ηB _OFFSET (t _A );
The step of obtaining the coefficient D _η (T _S ), which is the output of the predetermined third function, by inputting the time length T _S of the stop period to the predetermined third function, The function is an arbitrary stop time length t _{SA at} which the magnetron stops the generation of the high frequency, and the magnetron when the magnetron continuously generates the high frequency immediately after the generation of the high frequency is stopped for a predetermined stop time length. A coefficient D _η (representing the ratio of the maximum fluctuation amount of the high frequency conversion efficiency of the magnetron when the magnetron continuously generates a high frequency immediately after the magnetron has stopped for the arbitrary fluctuation time of the high frequency conversion efficiency to the maximum fluctuation amount. defining a relationship with t _SA );
Using the first basic offset value ηB _OFFSET (T _L ), the coefficient B _η (P _fm ), the coefficient C _η , and the coefficient D _η (T _S ) in Equation (1), the high frequency of the magnetron _Obtaining an offset value η _OFFSET of conversion efficiency;

The current high-frequency conversion efficiency η _m and the offset value η _OFFSET , which are values obtained by dividing the traveling wave power included in the one or more measured values at the time when the use condition is satisfied, by the input power to the magnetron, Using the equation (2), obtaining a correction value η _C of the high-frequency conversion efficiency;

Further including
The current parameter includes a correction value η _C for the high-frequency conversion efficiency,
In the step of determining the lifetime of the magnetron, the correction value η _C of the high-frequency conversion efficiency included in the current parameter is equal to or greater than a predetermined ratio with respect to the initial high-frequency conversion efficiency of the magnetron included in the initial parameter. Detecting the lifetime of the magnetron when it is degraded,
The method of claim 1. The current parameter includes an absolute value of the measured value of the anode voltage of the magnetron included in the one or more measured values at the time when the use condition is satisfied, as an absolute value of the current anode voltage of the magnetron. Including
In the step of determining the lifetime of the magnetron, the absolute value of the current anode voltage of the magnetron included in the current parameter is set to the absolute value of the initial anode voltage of the magnetron included in the initial parameter. The method according to any one of claims 1 to 3, wherein a lifetime of the magnetron is detected when it increases by a predetermined value or more. By inputting an elapsed time length _TL from the start time point to the time point when the use condition is satisfied to a predetermined fourth function, a second basic offset value that is an output of the predetermined fourth function VB _OFFSET (T _L ) is obtained, and the predetermined fourth function is an arbitrary value in the period from the start of a period in which the magnetron continuously generates a high frequency under a predetermined traveling wave power setting. An elapsed time length t _A until a time point, an anode voltage of the magnetron at the arbitrary time point, and an anode voltage of the magnetron when the magnetron continuously generates a high frequency under the predetermined traveling wave power setting. Defining a relationship with a second basic offset value VB _OFFSET (t _A ) that is an absolute value of a difference from the convergence value;
By inputting the measured value P _fm of the traveling wave power at the time when the use condition is satisfied to a predetermined fifth function, a coefficient B _V (P _fm) that is an output of the predetermined fifth function ) is a step of acquiring, the predetermined fifth function, and any forward power P _a, the of when the magnetron is continuously generates a high-frequency settings of a said given forward power P _{a A} relationship between a predetermined value as the maximum fluctuation amount of the magnetron anode voltage and a coefficient B _V (P _A ) representing a ratio of the second basic offset value VB _OFFSET (t _A ) to a predetermined maximum value is determined. The step;
The offset value of the anode voltage of the magnetron obtained in the period in which the magnetron is generating high frequency immediately before the stop period in which the magnetron has stopped generating high frequency immediately before the start time is the second basic value. Obtaining a coefficient C _V by dividing by the predetermined maximum value of the offset value VB _OFFSET (t _A );
The step of obtaining the coefficient D _V (T _S ), which is the output of the predetermined sixth function, by inputting the time length T _S of the stop period to the predetermined sixth function, The function is an arbitrary stop time length t _{SA at} which the magnetron stops the generation of the high frequency, and the magnetron when the magnetron continuously generates the high frequency immediately after the generation of the high frequency is stopped for a predetermined stop time length. Coefficient D _V (t _SA) representing the ratio of the maximum fluctuation amount of the anode voltage of the magnetron when the magnetron continuously generates a high frequency immediately after the arbitrary stop time length and the maximum fluctuation amount of the anode voltage. The step of determining the relationship with
Using the second basic offset value VB _OFFSET (T _L ), the coefficient B _V (P _fm ), the coefficient C _V , and the coefficient D _V (T _S ) in equation (3), the anode of the magnetron _{Obtaining a} voltage offset value V _OFFSET ;

The current anode voltage measurement value V _m and the offset value V _OFFSET of the magnetron included in the one or more measurement values at the time when the use condition is satisfied are used in Equation (4) to calculate the anode voltage determining a correction value V _C of the absolute value,

Further including
In the step of determining the life of the magnetron, the correction value V _C of the absolute value of the anode voltage in the current parameter, the predetermined value to the initial anode voltage of the magnetron included in the initial parameter Detecting the lifetime of the magnetron if it has increased above,
The method according to claim 1. The current parameter includes a measurement of the anode current of the magnetron included in the one or more measurements at the time when the usage condition is satisfied as a current anode current of the magnetron;
In the step of determining the lifetime of the magnetron, the current anode current of the magnetron included in the current parameter is increased by a predetermined value or more with respect to the initial anode current of the magnetron included in the initial parameter. 6. The method according to any one of claims 1 to 5, wherein a lifetime of the magnetron is detected when it is present. By inputting an elapsed time length _TL from the start time point to the time point when the use condition is satisfied to a predetermined seventh function, a third basic offset value that is an output of the predetermined seventh function IB _OFFSET (T _L ) is a step of obtaining the predetermined seventh function, from the start of a period in which the magnetron generates a high frequency under a predetermined traveling wave power setting to any point in time during the period An elapsed time length t _A , an anode current of the magnetron at the arbitrary time point, and a convergence value of the anode current of the magnetron when the magnetron continuously generates a high frequency under the predetermined traveling wave power setting, Determining a relationship with a third basic offset value IB _OFFSET (t _A ) that is an absolute value of the difference between
By inputting the measured value P _fm of the traveling wave power at the time when the use condition is satisfied to a predetermined eighth function, a coefficient B _I (P _fm) that is an output of the predetermined eighth function ) is a step of acquiring, the predetermined eighth function, and any forward power P _a, of the magnetron when the magnetron is continuously generating a high frequency under setting said given traveling wave power Defining a relationship between a predetermined value as the maximum fluctuation amount of the anode current and a coefficient B _I (P _A ) representing a ratio of the third basic offset value IB _OFFSET (t _A ) to a predetermined maximum value; Steps,
The offset value of the anode current of the magnetron obtained in the period in which the magnetron is generating high frequency immediately before the stop period in which the magnetron has stopped generating high frequency immediately before the start time is the third basic value. Obtaining a coefficient C _I by dividing by the predetermined maximum value of the offset value IB _OFFSET (t _A );
The step of obtaining the coefficient D _I (T _S ), which is the output of the predetermined ninth function, by inputting the time length T _S of the stop period to the predetermined ninth function, The function is an arbitrary stop time length t _{SA at} which the magnetron stops the generation of the high frequency, and the magnetron when the magnetron continuously generates the high frequency immediately after the generation of the high frequency is stopped for a predetermined stop time length. A coefficient D _I (t _SA) representing a ratio of the maximum fluctuation amount of the anode current of the magnetron when the magnetron continuously generates a high frequency immediately after the arbitrary stop time length and the maximum fluctuation amount of the anode current. ) For determining the relationship of
Using the third basic offset value IB _OFFSET (T _L ), the coefficient B _I (P _fm ), the coefficient C _I , and the coefficient D _I (T _S ) in equation (5), the anode of the magnetron _{Obtaining a} current offset value I _OFFSET ;

Measurements I _m and the offset value I _OFFSET current anode current of the magnetron included in the one or more measurements of the time when the use condition is satisfied by using the equation (6), the anode current determining a correction value _{I C,}

Further including
In the step of determining the life of the magnetron, the correction value I _C of said anode current included in the current parameter, increased more than a predetermined value relative to the initial anode current of the magnetron is included in the initial parameter 6. A method according to any one of claims 1 to 5, wherein the lifetime of the magnetron is detected if it is. The current parameter includes, as the current peak frequency of the traveling wave, a measurement value of the traveling wave peak frequency included in the one or more measured values at the time when the use condition is satisfied,
In the step of determining the lifetime of the magnetron, a current peak frequency of the traveling wave included in the current parameter is decreased by a predetermined value or more with respect to an initial peak frequency of the traveling wave included in the initial parameter. 8. The method according to any one of claims 1 to 7, wherein the lifetime of the magnetron is detected when it is present. By inputting an elapsed time length _TL from the start time point to the time point when the use condition is satisfied to a predetermined tenth function, a fourth basic offset value that is an output of the predetermined tenth function FB _OFFSET (T _L ) is obtained, and the predetermined tenth function is an arbitrary value in the period from the start of a period in which the magnetron continuously generates a high frequency under a predetermined traveling wave power setting. The elapsed time length t _A to the time point, the peak frequency of the traveling wave of the magnetron at the arbitrary time point, and the magnetron when the magnetron continuously generates a high frequency under the predetermined traveling wave power setting. Determining a relationship with a fourth basic offset value FB _OFFSET (t _A ) that is an absolute value of a difference from a convergence value of a peak frequency of a traveling wave;
By inputting the measured value P _fm of the traveling wave power at the time when the use condition is satisfied to a predetermined eleventh function, a coefficient B _F (P _fm) which is an output of the predetermined eleventh function ) is a step of acquiring, the predetermined eleventh function, and any forward power P _a, the when the magnetron is continuously generates a high-frequency settings of a said given forward power P _a The relationship between a predetermined value as the maximum fluctuation amount of the peak frequency of the traveling wave and a coefficient B _F (P _A ) representing a ratio of the fourth basic offset value FB _OFFSET (t _A ) to a predetermined maximum value is expressed as follows. Defining the steps;
The offset value of the peak frequency of the traveling wave obtained in the period in which the magnetron is generating high frequency immediately before the stop period in which the magnetron has stopped generating high frequency immediately before the start time is the fourth value. Obtaining a coefficient C _F by dividing by a predetermined maximum value of the basic offset value;
The step of obtaining the coefficient D _F (T _S ), which is the output of the predetermined twelfth function, by inputting the time length T _S of the stop period to the predetermined twelfth function, The function is an arbitrary stop time length t _{SA at} which the magnetron stops the generation of the high frequency, and a peak of the traveling wave when the magnetron continuously generates the high frequency immediately after the generation of the high frequency is stopped for a predetermined stop time length. Coefficient D _F (t _SA ) representing the ratio of the maximum fluctuation amount of the peak frequency of the traveling wave when the magnetron continuously generates a high frequency immediately after the arbitrary stop time length and the maximum fluctuation amount of the frequency. Defining the relationship between
Using the fourth basic offset value F _BOFFSET (T _L ), the coefficient B _F (P _fm ), the coefficient C _F , and the coefficient D _F (T _S ) in Equation (7), Obtaining a peak frequency offset value F _OFFSET ;

Using the measured value F _m of the traveling wave peak frequency and the offset value F _OFFSET included in the one or more measured values at the time when the use condition is satisfied, determining a correction value F _C of the peak frequency,

Further including
In the step of determining the life of the magnetron, a predetermined value to the initial peak frequency of the traveling wave correction value F _C of the traveling wave of peak frequencies contained in said current parameter is included in the initial parameter Detecting the lifetime of the magnetron when it has decreased above,
The method according to any one of claims 1 to 7. Predicting the remaining length of time to the current lifetime of the magnetron;
In the step of predicting the remaining time length,
With reference to data in which the magnetron usage time length and the magnetron high-frequency conversion efficiency are associated with each other, the current magnetron usage time length corresponding to the current high-frequency conversion efficiency is obtained,
The difference between a preset magnetron life time length and the current magnetron usage time length is determined as the remaining time length.
The method according to claim 2 or 3. Predicting the remaining length of time to the current lifetime of the magnetron;
In the step of predicting the remaining time length,
Using the current usage time length t _c of the magnetron, the initial high-frequency conversion efficiency η _ic , and the current high-frequency conversion efficiency η _m , a constant A is calculated based on Equation (9),

Using the predetermined high frequency conversion efficiency η _d at the lifetime of the magnetron, the calculated constant A, and the initial high frequency conversion efficiency η _ic , the life time length t _d is calculated based on the equation (10). Calculate

Calculating the difference between the calculated life time length t _d and the current use time length t _c as the remaining time length;
The method according to claim 2 or 3.