JP5141519B2 - Plasma processing apparatus and method of operating plasma processing apparatus - Google Patents

Description

  The present invention relates to a plasma processing apparatus that converts a processing gas into plasma by high-frequency power and performs processing such as etching on the object to be processed by the plasma, and particularly relates to a technique for changing the state of the apparatus of the plasma processing apparatus.

  In the manufacturing process of a flat panel display (FPD) such as a semiconductor device or a liquid crystal display device, a plasma etching apparatus for performing an etching process on a target object such as a semiconductor wafer or a glass substrate, or a plasma CVD process for performing a film forming process. A plasma processing apparatus such as an apparatus is used.

  For example, in an etching apparatus that applies high-frequency power to parallel plate-type electrodes and etches an object to be processed by capacitively-coupled plasma formed between the electrodes, one side of the electrodes that are vertically opposed to each other, For example, a high-frequency power source for plasma formation (hereinafter referred to as a source) is connected to a lower electrode (lower electrode) that also serves as a mounting table for an object to be used as a cathode electrode, and a high-frequency bias is applied to the lower electrode. What connected the power supply is known. The high-frequency power source for bias plays a role of supplying electric power for attracting ions in the plasma toward the object to be processed to ensure etching anisotropy and to prevent abnormal discharge.

  In starting up such an etching processing apparatus, plasma is formed between parallel plate electrodes by starting the supply of high-frequency power from the above-described high-frequency power sources to the lower electrode. When applied over time, for example, matching by a matching circuit provided between the high-frequency power source and the lower electrode cannot be achieved, and a reflected wave is generated from the lower electrode side toward each high-frequency power source. This reflected wave becomes an obstacle to forming a stable plasma and causes a long time to start up the etching apparatus. For example, power supply from a high frequency power source on the source side or bias side is performed in multiple stages. A technique is known in which a reflected wave generated at the time of startup is reduced by dividing and gradually applying power (see, for example, Patent Document 1).

  FIG. 10 schematically shows an example of a conventional sequence in which power is applied to the lower electrode from each of the source-side and bias-side high-frequency power supplies. In this example, the source-side and bias-side are controlled in order to suppress the influence of reflected waves. The power supply from each of the high-frequency power sources on the side is performed, for example, in two stages. 10 (a) and 10 (c) show timings at which each high-frequency power supply receives an activation signal (ON / OFF signal) transmitted from a host computer (control unit) that controls operation control of the entire etching processing apparatus. Show. 10 (b) and 10 (d) show the high-frequency power supplied to the lower electrode from each high-frequency power source (represented by a solid line in each figure) and propagate from the lower electrode side toward each high-frequency power source. The time-dependent change of each power value of the power of the reflected wave (shown by a broken line) is shown. The horizontal axis of each figure of Fig.10 (a)-FIG.10 (d) has shown time.

According to the conventional power supply sequence, while the high frequency power source receives the activation signal from the control unit at time T _1, the high-frequency power supply source side to wait without starting the application of power to the lower electrode, the bias The high-frequency power supply on the side gradually increases the applied power until it reaches a predetermined power value (hereinafter referred to as first-stage power) lower than the power value during the process. At this time, the reflected wave generated on the electrode side propagates to the high frequency power source on the bias side, but the power of the reflected wave is relatively small due to the stepwise application of the high frequency power, If the reflected wave is short due to the action of the matching circuit, it is attenuated in about 1 second to 2 seconds, for example.

The applied power from the high frequency power source of bias side reaches the first stage round of power is expected to reflected wave bias side with time determined in advance from the time T ₁ of the aforementioned is sufficiently attenuated at time T _2, in turn starts the application of the first stage time of the power from the high frequency power source side. At this time, the reflected wave propagates to both the source side and the bias side of the high-frequency power source including the bias side where power supply has already started. These reflected waves are eventually attenuated by the action of the matching circuit. .

In this way, the time interval until the matching is completed in which the reflected wave is sufficiently attenuated is set in advance. For example, at times T _{2 to} T ₄ when the set times have elapsed from the application start time T ₁ of the high frequency power, For example, the first stage power is applied on the bias side (time T ₁ ) → the first stage power is applied on the source side (time T ₂ ) → the process power is applied on the bias side (time T ₁ ). ₃ ) → Apply process power on the source side (time T ₄ ), and increase the high frequency power on the bias side and the source side alternately in steps, thereby suppressing the influence of the reflected wave and as much as possible. A power supply sequence for starting the etching processing apparatus in a short time has been adopted.

  However, in an etching process using a glass substrate for FPD as an object to be processed, it is necessary to process an object to be processed having a long side as long as 2 m due to the recent increase in size of the glass substrate. The size of the lower electrode, which also serves as a mounting table, has become very large.

When the size of the lower electrode is increased, the space in which the plasma is formed increases, so that the power of the reflected wave increases as the power required for plasma formation and the like increases. In some cases, more than a second is required. Therefore, in the power supply sequence to increase the applied power for example every few seconds as described above, for example, FIG. 10 (b), the as shown at time T ₄ in FIG. 10 (d), the reflection that occurred in the previous step The power supply of the next step is started before the wave is attenuated, and the reflected wave propagates in the circuit of the etching apparatus in a superimposed manner, so that it is difficult to form a stable plasma. .

In order to avoid such a trouble, it is also conceivable to ensure a sufficient matching time by setting the interval between the times T _{2 to} T ₄ longer than before. However, the time required for matching is not constant, and even when the lower electrode is enlarged, matching may be completed in about 1 second to 2 seconds, for example. Despite the completion of matching, the waiting time for not proceeding to the next step (indicated as Δt ₁ and Δt ₂ in FIG. 10D) increases, and the startup time of the etching processing apparatus becomes unnecessary. There is a high risk of prolonged use.

  Therefore, for example, in Patent Document 2 and Patent Document 3, the power of the reflected wave is monitored by a wattmeter or the like, and after confirming that the value is smaller than a predetermined threshold, A technique for applying is described.

As described above, Patent Documents 1 to 3 individually describe a technique for applying high-frequency power in stages and a technique for applying high-frequency power in the next step while monitoring reflected waves generated by the application of high-frequency power. Have been described. However, for example, as shown in FIG. 10, there is no disclosure of an optimal power supply sequence or a device configuration suitable for this sequence when the source side and bias side high frequency power is applied stepwise.
Table No. WO99 / 11103: 11th page, 4th line to 16th line, FIG. JP 2007-214589 A; Paragraphs 0059 to 0061, FIGS. 15 and 16 JP 2007-12555 A: paragraphs 0028 to 0029, FIG.

The present invention has been made in view of such circumstances, and an object of the present invention is to perform plasma processing that can change the state of the apparatus stably and in a short time (it is possible to start plasma or change the state of plasma ). An object of the present invention is to provide an apparatus and a method for operating a plasma processing apparatus.

The plasma processing apparatus according to the present invention includes a plurality of high-frequency power source for outputting a high frequency in the processing chamber, the plasma by then process the object to be processed in the processing chamber, or for a plasma to launch plasma In the plasma processing apparatus that changes the output power of each of the plurality of high-frequency power supplies in stages to change the state,
A high-frequency power supply unit that is provided for each high-frequency power supply and includes a high-frequency power supply, a power control unit that controls the output of the high-frequency power supply, and a reflected wave measurement unit that measures a power value of a reflected wave reflected by the high-frequency power supply;
Means for determining whether or not the measured power value of the reflected wave of each high-frequency power source is equal to or lower than a threshold value;
Change the output power of other high-frequency power supply other than one high-frequency power supply from one stage to another, and the measured power value of the reflected wave of the other high-frequency power supply generated based on the change is below the threshold value after becoming, characterized in that a timing signal for changing the output power of the one of the high-frequency power source when the elapsed preset time and means for providing to the power control unit.

  The timing signal includes a condition that the measured power value of the reflected wave of the other high-frequency power source is less than or equal to a threshold value, and a condition that the measured power value of the reflected wave of the one high-frequency power source is less than or equal to the threshold value. It is preferable that the time period is generated when a preset time elapses after the two conditions are satisfied.

Furthermore, the reflected wave information is transmitted between the high-frequency power supply units, and the measured power value of the reflected wave between the high-frequency power supply units or a determination signal indicating that the measured power value is equal to or less than a threshold value. A signal transmission path is provided for directly performing, and means for supplying the timing signal to the power control unit is provided in each high-frequency power supply unit, and the reflected wave information of other high-frequency power supplies sent from the signal transmission path. Means for generating the timing signal on the basis thereof may be included. Further, the means for giving the timing signal to the power control unit is means for determining whether or not the measured power value of the reflected wave of its own high-frequency power source is equal to or lower than a threshold value, the determination result in this means, and the signal It is preferable to include means for generating the timing signal based on the reflected wave information of another high frequency power source sent from the transmission line.
Preferably, the means for determining whether or not the measured power value of the reflected wave of the high frequency power source is equal to or less than the threshold value and the means for generating the timing signal are configured by a logic circuit.

The method of operating a plasma processing apparatus according to another invention includes a plurality of high-frequency power source for outputting a high frequency in the processing vessel, then process target object in the processing chamber by the plasma, up the plasma In the operation method of the plasma processing apparatus for changing the output power of each of the plurality of high-frequency power supplies stepwise in order to increase or change the plasma state,
Measuring the power value of the reflected wave of each high-frequency power supply;
The output power of another high frequency power supply other than one high frequency power supply is changed from one stage to another stage, and the measured power value of the reflected wave of the other high frequency power supply generated based on the change is below the threshold value. Determining whether or not there is,
And changing the output power of the one high-frequency power source when a preset time has elapsed after it has been determined that the measured power value of the reflected wave of the other high-frequency power source has fallen below a threshold value. It is characterized by.

Also, at this time, comprising a step of determining whether or not the measured power value of the reflected wave of the one high-frequency power supply is below a threshold value,
The step of changing the output power of the one high-frequency power source includes the condition that the measured power value of the reflected wave of the other high-frequency power source is equal to or lower than a threshold value and the measured power value of the reflected wave of the one high-frequency power source. Preferably, this is performed when a preset time has elapsed after both conditions, i.e., the condition that is less than or equal to the threshold value, are satisfied.

  According to the present invention, in a plasma processing apparatus that changes the output power of a plurality of high-frequency power supplies in stages when the state of the apparatus is changed, the reflected wave of another high-frequency power supply is measured for one high-frequency power supply that changes the output power. Since the output power of the one high-frequency power supply is changed when a preset time has elapsed after the power value becomes equal to or lower than the threshold value, for example, the next step is waited for the preset time to elapse. Compared with the method of applying high-frequency power, the next step is executed before the reflected wave is sufficiently attenuated, and the reflected wave propagates in the circuit of the etching apparatus in a superimposed manner so that the state of the apparatus cannot be changed. While it is possible to prevent the occurrence and stably change the state of the plasma processing apparatus, when the reflected wave decays quickly, the next scan can be performed quickly without causing unnecessary waiting time. Tsu running up can realize the change of state of rapid equipment.

  In addition, for the one high-frequency power source, the method for determining that the measured power value of the reflected wave of the other high-frequency power source is equal to or lower than the threshold value was directly sent from the signal transmission path provided between the high-frequency power source units. By making it based on the reflected wave information of other high-frequency power supplies, it is possible to suppress delays in the timing of changing the output power of the high-frequency power supplies. After the power becomes smaller than the threshold value, the output power control operation can be started more quickly.

  An embodiment in which the present invention is applied to activation of an etching processing apparatus 1 which is an example of a change in the state of an etching processing apparatus 1 for etching a substrate S for a liquid crystal display will be described below. FIG. 1 shows the overall configuration of an etching processing apparatus 1 according to the present embodiment. The etching processing apparatus 1 includes a processing container 10 made of aluminum whose surface is anodized, for example. The processing container 10 has, for example, a corner having a size of about 3.5 m on one side of the horizontal section and about 3.0 m on the other side so that a large square substrate S having a long side of 2 m or more can be processed. It is formed in a cylindrical shape.

  A lower electrode 41 is provided in the central portion on the bottom side in the processing container 10, and the lower electrode 41 also has a function as a mounting table on which a substrate S transferred from outside by a transfer means (not shown) is mounted. . An insulator 42 is provided below the lower electrode 41, and the lower electrode 41 is in an electrically floating state from the processing container 10 by the insulator 42. In the figure, reference numeral 43 denotes a support portion for the lower electrode 41. In addition, an opening 44 is provided in the lower part of the processing container 10, and a matching box 16 that forms a grounded housing is provided outside the opening 44.

  Matching boxes 16 are provided with matching circuits 161 and 162 each having one end connected to a plasma forming (source) high frequency power supply unit 2 and a bias applying high frequency power supply unit 3 via, for example, coaxial cables. The other ends of the matching circuits 161 and 162 are connected to the lower electrode 41. The matching circuits 161 and 162 perform impedance adjustment (matching) between the lower electrode 41 and each of the high-frequency power sources 2 and 3 in accordance with the impedance of the plasma, and play a role of attenuating reflected waves generated in the circuit of the etching processing apparatus 1. .

  An exhaust passage 14 is connected to the side wall of the processing container 10, and a vacuum pump 15 is connected to the exhaust passage 14. Further, on the side wall of the processing container 10, a transport port 11 for loading and unloading the substrate S between the outside and the processing container 10 and a gate valve 12 for opening and closing the transport port 11 are provided.

  An upper electrode 51 is provided above the lower electrode 41 so as to face the lower electrode 41, and the upper electrode 51 supplies a processing gas for etching processing to the processing space 13 in the processing container 10. It also has a function as a shower head. The upper electrode 51 is fixed to the ceiling surface of the processing container 10 via an insulator 52 provided along the edge of the opening 56 of the ceiling of the processing container 10, and is connected to the upper surface of the processing container 10 via the conductive path 57 and the conductive cover 58. It is electrically connected to the processing container 10. Further, the processing container 10 is grounded.

  In the upper electrode 51, a gas supply path 59 having a gas hole 55 opening toward the mounting surface of the substrate S on the lower electrode 41 is formed, and this gas supply path 59 is connected to the gas supply path 53. The processing gas is connected to the processing gas supply unit 54, and the processing gas from the processing gas supply unit 54 can be supplied into the processing space 13.

  Each of the high frequency power supply units 2 and 3 of the etching processing apparatus 1 having the above-described configuration prevents the occurrence of a failure in plasma formation due to the influence of the reflected wave at the time of startup. The output of the high frequency power is increased step by step while monitoring the generation of reflected waves that are reflected back to the high frequency power sources 21 and 31 from the output side (load side) of the high frequency power sources 21 and 31 provided therein. It has a function. Hereinafter, the details will be described with reference to FIGS.

  FIG. 2 is a block diagram showing the configuration of the source high-frequency power supply unit 2 and the bias high-frequency power supply unit 3. The source high frequency power supply unit 2 includes, for example, a high frequency power supply 21 that outputs a high frequency of 13.56 MHz and 10 kW, a power control unit 211 that controls the supply of high frequency power to the processing container 10 side (lower electrode 41), and the high frequency power supply 21. A timing signal generation unit 22 that supplies a timing signal for increasing the output in a stepwise manner to the power control unit 211 while monitoring a reflected wave generated on the load side, and a communication board 23. On the other hand, the bias high frequency power supply unit 3 includes, for example, a high frequency power supply 31 that outputs a high frequency of 3.2 MHz and 5 kW, a power control unit 311 that controls the supply of high frequency power to the processing container 10 side (lower electrode 41), and a high frequency A timing signal generation unit 32 that provides a timing signal for increasing the output stepwise at startup while monitoring a reflected wave generated on the load side of the power supply 31; and a communication board 33. Yes.

  The first ports 231 and 331 of the communication boards 23 and 33 are connected to the control board 101 of the control unit 100 described later, respectively, and receive an activation signal (ON / OFF signal) from the control unit 100 or perform processing. The measurement result of the power value of the power supplied to the container 10 (hereinafter referred to as traveling wave) and the power value of the reflected wave may be transmitted from the high frequency power supplies 21 and 31 to the control unit 100. It can be done.

  Further, the second port 232 of the source high-frequency power supply unit 2 is connected to the second port 332 of the bias high-frequency power supply unit 3 through a signal transmission line, The measured power value of the reflected wave can be transmitted to the timing signal generation unit 32 of the high frequency power supply unit 3 for bias. On the other hand, the third port 333 of the high frequency power supply unit 3 for bias is connected to the third port 233 of the high frequency power supply unit 2 for source 2 via a signal transmission path, and is connected to the high frequency power supply 31 of the high frequency power supply unit 3 for bias. The power value of the reflected wave measured in this way can be transmitted to the timing signal generator 22 of the source high frequency power supply unit 2. In this way, the power supply units 2 and 3 can monitor the reflected waves measured by the counterpart power supply units 3 and 2 with each other.

  In each of the high frequency power supply units 2 and 3, the high frequency power supply 21 and the timing signal generation unit 22 on the source high frequency power supply unit 2 side, and the high frequency power supply 31 and the timing signal generation unit 32 on the bias high frequency power supply unit 3 side are mutually connected. The reflected signals that are connected and propagated toward the power supply units 2 and 3 can be monitored by the timing signal generators 22 and 32, respectively. Each timing signal generation unit 22, 32 generates a timing signal described later based on the monitoring result of the reflected wave that has propagated toward both the power supply unit 2, 3 on both sides and the power control unit 211, On the other hand, the power control units 211 and 311 output control signals to the high-frequency power sources 21 and 31 based on this timing signal, and increase the outputs of the high-frequency power sources 21 and 31 step by step. Can do.

  3 and 4 are configuration diagrams showing the internal configuration in each of the high-frequency power supply units 2 and 3. First, the source high-frequency power supply unit 2 shown in FIG. 3 will be described. The timing signal generation unit 22 is a timing for increasing the output of the high-frequency power stepwise based on the reflected wave of its own high-frequency power and the reflected wave of the bias side power. It is for generating a signal. 224 is a comparator, and the power value of the reflected wave measured by its own reflected wave wattmeter 214 is a preset threshold value (first threshold, for example, a reflected wave wattmeter 214 described later in this example). A logic “1” is output when the detection lower limit is exceeded. A negative circuit 225 applies a signal A2 obtained by inverting the output of the comparator 224 to a subsequent one-shot multivibrator (hereinafter referred to as OMV) 223.

  Reference numeral 221 denotes a comparator, which is measured on the bias high frequency power supply unit 3 side, and the power value of the transmitted reflected wave is a preset threshold value (second threshold, for example, a reflected wave described later in this example). A logic “1” is output when the detection limit of the wattmeter 314 is exceeded. A pulse output circuit 222 outputs a pulse signal A1 having a preset length when the output of the comparator 221 drops from “1” to “0”. The pulse output circuit 222 is configured by combining, for example, a differentiation circuit and OMV.

  Reference numeral 223 denotes an OMV, which is a timing when the logic of both input terminals becomes “1”, that is, when the output signal A1 of the pulse output circuit 222 and the output signal A2 of the negation circuit 225 become “1”. This is for supplying a pulse signal A3, which is a signal, to the power control unit 211. Therefore, the timing signal generation unit 22 has the power value of the reflected wave of its own high-frequency power being equal to or lower than the first threshold value, and once the power value of the high-frequency power on the bias side is increased, A timing signal is output to the power control unit 211 when it becomes smaller than the threshold value.

  The power control unit 211 plays a role of controlling the output of the high-frequency power source 21 based on a start signal (ON / OFF signal) from the control unit 100 and a timing signal from the timing signal generation unit 22 side. The high frequency power source 21 supplies a high frequency power between the lower electrode 41 and the upper electrode 51 to output a high frequency power for plasmaizing (activating) the processing gas, and a high frequency power source body 212. The traveling wave supplied to the processing container 10 side (lower electrode 41) and the reflected wave propagating from the processing container 10 side toward the high frequency power supply unit 2 for the source are directed to the reflected wave wattmeter 214 and the traveling wave wattmeter 215, respectively. And a directional coupler 213 to be taken out.

In the power control unit 211, the ON / OFF signal from the control unit 100 side is ON, and the standby time Δt ₀ set in advance from the time when the pulse signal A3 that is the timing signal is received from the timing signal generation unit 22 is set. At the elapsed time, the high frequency power supply 21 is controlled so as to increase the output of the high frequency power to a preset power value. For example, the power control unit 211 has a function of incrementing and storing the number of times the pulse signal A3 is received from the OMV 223, and the output of the high-frequency power source body 212 is determined according to the number of times the pulse signal A3 is received. The output increase speed of the high-frequency power source body 212 is set in advance.

  With these functions, for example, the high-frequency power supply 21 of the source high-frequency power supply unit 2 in this example can increase the high-frequency power in two steps, as described above from the time when the pulse signal A3 is received for the first time. After the standby time elapses, for example, the output of the high-frequency power applied from the source side is increased from 0 kW to 5 kW (first stage power) over 1 second to 2 seconds, and the pulse signal A3 is received for the second time. After the elapse of the standby time from the time point, the output is increased from 5 kW to 10 kW (power during the process) within the same time.

  The reflected wave wattmeter 214 and the traveling wave wattmeter 215 each serve to measure the power value of the traveling wave and the reflected wave extracted by the directional coupler 213, and the reflected wave measured by the reflected wave wattmeter 214. The power value (corresponding to the reflected wave information) is output in real time to the timing signal generation unit 22, the timing signal generation unit 32 on the bias high-frequency power supply unit 3 side, and the control unit 100 in real time. . On the other hand, the power value of the traveling wave measured by traveling wave wattmeter 215 is output to controller 100 in real time.

  Before describing the overall operation of the etching processing apparatus 1 according to the embodiment, the operation of the timing signal generation unit 22 and the operation of the power control unit 211 will be described. A brief description will be given with reference to FIGS. 7A to 7D schematically showing an example of a sequence in which high-frequency power is applied from 3 to the lower electrode 41. The contents of instructions in each figure are the same as those shown in FIGS. 10 (a) to 10 (d) described in the background art.

Now, the power values of the traveling wave and the reflected wave measured by each of the high frequency power supply units 2 and 3 are before the time T ₂ ′ shown in FIG. 7, and the power value of the reflected wave on the bias side is as described above. It is assumed that the value is larger than the second threshold value. At this time, since no high frequency power is applied to the source side as shown in FIG. 7B, the power values of both the traveling wave and the reflected wave measured by the high frequency power source 21 on the source high frequency power supply unit 2 side are Zero. For this reason, since the output of the comparator 224 is “0”, the input signal A2 on the other side of the OMV 223 is “1”. At this time, since the power value of the reflected wave input to the comparator 221 exceeds the second threshold value as described above, no pulse is output from the pulse output circuit 222. Therefore, the input signal A1 on one side of the OMV 223 is “0”.

  Then, as shown in FIG. 7D, when the reflected wave generated on the bias high-frequency power supply unit 3 side attenuates and the power value input to the comparator 221 of the timing signal generator 22 falls below the second threshold value. The output of the comparator 221 changes from “1” to “0”. This change is detected by the differentiating circuit in the pulse output circuit 222, and a pulse signal is output from the pulse output circuit 222 to the OMV 223.

Therefore, one input signal A1 of the OMV 223 becomes “1”, the input condition (AND condition) of the OMV 223 is satisfied, and the pulse signal A3 that is the first timing signal is output from the OMV 223. As a result, the power control unit 211 performs an operation of increasing the output of the high frequency power supply 21 from 0 kW to 5 kW (first stage power) from time T ₂ ′ after the elapse of the preset standby time t ₀ .

Next, at the timing before time T ₄ ′ shown in FIG. 7, the timing at which the reflected waves generated on the source side and the bias side fall below the first and second threshold values is detected, and the high frequency An operation for increasing the output of the power supply 21 will be described. In this case, since the first stage power smaller than the power at the time of the process is already applied to the source side from the high frequency power source 21, the output of the bias side high frequency power source 31 increased at the time T ₃ ′. As a result, a reflected wave is also generated on the source side, and the power value of the reflected wave is measured by the reflected wave wattmeter 214 and input to the comparator 224.

  While the power value of the reflected wave exceeds the first threshold value, the other input signal A2 of the OMV 223 is in the “0” state, and the power value falls below the first threshold value. And the input signal A2 becomes "1". On the other hand, the input condition of the OMV 223 is satisfied as described above at the timing when the power value of the reflected wave on the bias side falls below the second threshold value, and the pulse signal A3 which is the second timing signal from the OMV 223 is the power. It is output to the control unit 211.

As a result, after the elapse of the standby time Δt ₀ , the power control unit 211 performs an operation of increasing the output of the high frequency power supply 21 from 5 kW to 10 kW (power during the process) from time T ₄ ′.

By the way, for example, as can be seen from the time-dependent change in the power value of the reflected wave generated after time T ₃ ′ in FIGS. In the example, the reflected wave generated in the bias-side high-frequency power supply 31) takes a longer time to attenuate, and the reflection generated in the counterpart side (in this example, the source-side high-frequency power supply 21) whose output is not increased. The wave decays in a relatively short time. In this case, in the timing signal generation unit 22 shown in FIG. 3, first, the power value of the reflected wave on the source side is lower than the first threshold value, and the output signal from the negation circuit 225 is “1”. Subsequently, the power value of the reflected wave on the bias side falls below the second threshold value, and a pulse signal is output from the pulse output circuit 222. As a result, both input signals A1 and A2 of the OMV 223 become “1” and the power The pulse signal A3 is output to the control unit 211.

  As described above, when signals are input to the OMV 223 in the order of signal A2 → pulse signal A1, even if the timing at which each reflected wave attenuates greatly deviates from the other, the OMV 223 has a bias-side reflected wave attenuated later. It is possible to operate the power control unit 211 by grasping the timing when the threshold value is below.

  On the other hand, contrary to the example shown in FIGS. 7B and 7D, the attenuation of the reflected wave generated on the high-frequency power source side (in this example, the bias-side high-frequency power source 31) whose output is increased. Consider a case where a situation occurs in which the timing of attenuation of the reflected wave generated on the other side (in this example, the high frequency power supply 21 on the source side) whose output is not increased is delayed. In this case, if the time width of the pulse signal A1 output from the pulse output circuit 222 is set to be short, for example, the attenuation of the reflected wave on the bias side is detected and the pulse signal A1 is output from the pulse output circuit 222. After the level of the pulse signal falls (the pulse signal disappears), when the attenuation of the reflected wave on the source side is detected and the signal A2 on the negative circuit 225 side becomes “1”, the input condition of the OMV 223 is satisfied. Disappear.

Therefore, the pulse output circuit 222 according to the embodiment is configured to output the pulse signal A1 having a predetermined time width, for example, about several seconds as described above, and does not increase the output, for example. The reflected wave generated in the high-frequency power source (for example, the source-side high-frequency power source 21 at the timing after time T ₃ ′) is attenuated after the high-frequency power source (in this example, the bias-side high-frequency power source 31) whose output is increased. Even when the input signal A1 is in the state of “1” for a certain period of time, it is possible to grasp the timing when the reflected wave on the source side attenuated later falls below the threshold value and The controller 211 can be operated.

Note that the timing at which the two reflected waves attenuate greatly differs, and the output of the negation circuit 225 becomes “1” at a timing later than the time width of the pulse signal A1 output from the pulse output circuit 222. In this case, for example, it is detected that the power applied to the lower electrode 41 does not increase even if a preset time has elapsed in the upper control unit 100 and this is notified to the operator, or the source high-frequency power supply The power application operation from the unit 2 and the bias high-frequency power supply unit 3 may be performed again.
The signal A1 output from the pulse output circuit 222 is configured to detect that the power value of the reflected wave on the bias side has fallen below the second threshold value and output a step signal that becomes “1”. However, in this case, for example, an operation of resetting the output from the pulse output circuit 222 at the timing of increasing the output of each of the high-frequency power supplies 21 and 31 (each time from time T ₁ ′ to time T ₄ ′) is performed. Necessary.

  As described above, the reflected wave generated by each of the high frequency power supplies 21 and 31 is monitored on the source high frequency power supply unit 2 side, and the power value is set to a preset threshold value (first threshold value, second threshold value). The configuration and operation of the circuit for increasing the output of the high-frequency power applied from the high-frequency power supply 21 on the source high-frequency power supply unit 2 side when the value is less than the value) have been described. The bias shown in FIG. The configuration and operation of the timing signal generation unit 32 and the high frequency power supply 31 on the high frequency power supply unit 3 side are substantially the same as the timing signal generation unit 32 on the source high frequency power supply unit 2 side described above.

  That is, whether or not the reflected wave measured by its own reflected wave wattmeter 314 exceeds a preset threshold value (third threshold value) by the comparator 324 is detected and inverted by the negation circuit 325. Then, the signal B 2 is given to the OMV 323. When the power value of the reflected wave measured and transmitted on the source high frequency power supply unit 2 side is attenuated to a value equal to or lower than a preset threshold value (fourth threshold value), the pulse output circuit 322 preliminarily A pulse signal B 1 having a set length is output to the OMV 323. The OMV 323 supplies a pulse signal B3, which is a timing signal, to the power control unit 311 when the logic of both input terminals is “1”. Therefore, the timing signal generation unit 32 has the power value of the reflected wave of its own high-frequency power being equal to or smaller than the third threshold value, and the reflected wave of the high-frequency power on the source side once increases, and then the fourth signal A timing signal is output to the power control unit 311 when it becomes smaller than the threshold value.

Similarly to the above-described one, the power control unit 311 is also preset in advance from the time when the ON / OFF signal from the control unit 100 side is ON and the pulse signal B3 as the timing signal is received from the timing signal generation unit 32. At the time when the set standby time Δt ₀ has elapsed, the output of the high frequency power supply 31 is increased to a preset power value. The power control unit 311 increments and stores the number of times the pulse signal B3 is received from the OMV 323, and the output of the high frequency power supply 31 is, for example, 0 kW → 2.5 kW depending on the number of times the pulse signal B3 is received (first stage As described above, the power consumption is increased from 2.5 kW to 5 kW (power during the process).

Here, immediately after the start of the activation of the bias high-frequency power supply unit 3, since no high-frequency power is output from either of the high-frequency power supplies 31, 21, no reflected wave is generated, so the OMV 323 generates a timing signal. I can't. Therefore, an OMV 326 is connected between the OMV 323 and the power control unit 311 via an OR circuit 327, and the OMV 326 converts the signal into a pulse signal B4 when the activation signal from the control unit 100 is turned on. The pulse signal B4 is output to the power control unit 311 as the first timing signal, and the increase in the output of the high frequency power supply 31 is started. In this respect, the bias-side high-frequency power supply unit 3 is different in configuration from the source high-frequency power supply unit 2 that has already been applied with high-frequency power and starts in a state in which a timing signal (pulse signal A3) can be output from the OMV 223. .
In addition, the high-frequency power source 31 includes a high-frequency power source main body 312, a directional coupler 313, a reflected wave wattmeter 314, and a traveling wave wattmeter 315, similar to the high-frequency power supply 21 on the source high-frequency power supply unit 2 side described above. It is.

  In the example described above, the timing signal A3 (B3) is output to the power control unit 211 (311), and then the control for increasing the power is performed after the time set in advance by the power control unit 211 (311). For example, a delay circuit that delays the output of the pulse signal by the preset time is provided at the subsequent stage of the OMV 223 (323), and the pulse signal output from the delay circuit is also used as the timing signal A3 (B3). Good. In this case, after the timing signal A3 (B3) is input to the power control unit 211 (311), a control operation for increasing the power is performed immediately.

  Next, returning to the description of the overall configuration of the etching apparatus 1, the above-described control unit 100 is configured as a computer including a CPU and a memory (not shown), for example. In addition to the above-described operations such as outputting a start signal (ON / OFF signal) and monitoring the power values of the traveling wave and the reflected wave from the high-frequency power supply units 2 and 3, the entire etching processing apparatus 1 Steps relating to overall control of the operation, i.e., control related to operations from loading the substrate S into the processing container 10 and performing etching processing on the substrate S placed on the lower electrode 41 until unloading ( A program having a group of instructions) is stored. This program is stored in a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card, and installed in the computer therefrom.

  Next, the operation of the etching processing apparatus 1 will be described with reference to the flowcharts of FIGS. 5 and 6 and FIGS. 7 (a) to 7 (d). First, an operator inputs processing conditions such as a gas type, a pressure in the processing container 10, and power during a process supplied from each of the high-frequency power units 2 and 3 from an input screen (not shown). Then, the gate valve 12 is opened, and the substrate S, for example, having a resist patterned on the surface and having a metal film formed thereon, is carried into the processing container 10 by an external transfer arm (not shown), and the transfer arm and the transfer arm are not shown. The substrate S is placed on the lower electrode 41 by the cooperative action with the lifting pins. Subsequently, the gate valve 12 is closed, and the processing chamber 10 is evacuated while supplying the processing gas into the processing chamber 10 from the upper electrode 51 that also serves as a gas shower head, and the processing space 13 is set to a set pressure.

Thereafter, as shown in the flowchart of FIG. 5, the power supply operation is started by the control unit 100, the bias high-frequency power supply unit 3, and the source high-frequency power supply unit 2. First, as shown in FIGS. 7A and 7C, the control unit 100 transmits an activation signal for turning on the source high-frequency power supply unit 2 and the bias high-frequency power supply unit 3 at time T ₁ ′. (Step S101), the operation relating to the power supply is ended (End). Hereinafter, the operation of applying source power and bias power to the lower electrode 41 is executed independently of the control of the control unit 100 in the source high-frequency power supply unit 2 and the bias high-frequency power supply unit 3.

  When each of the high frequency power supply units 2 and 3 receives the start signal in the “ON” state (steps S201 and S301), the power control unit 311 is activated by the action of the ON signal and the OMV 326 shown in FIG. First, the operation of applying a first-stage power lower than the power during the process from the bias-side high-frequency power supply 31 to the lower electrode 41 is immediately started (step S302). When the high frequency power is applied to the load side, a reflected wave is generated in the high frequency power supply 31, and the reflected wave power increases as the applied power increases as shown in FIG. . The power applied from the high-frequency power supply 31 becomes constant when the set value of the first stage power is reached, while the reflected wave power gradually decreases due to matching by the matching circuit 162.

  During this time, the power value of the reflected wave measured on the bias high-frequency power supply unit 3 side is transmitted in real time to the source high-frequency power supply unit 2 (step S303). The value is received (step S202), and the reflected wave on the bias high frequency power supply unit 3 side is monitored until the power value becomes equal to or lower than the second threshold (step S203; NO).

When it is detected by the action of the pulse output circuit 222 described above that the power value of the reflected wave once increases and then becomes smaller than the second threshold value (step S203; YES), the timing At time T ₂ ′ after the signal is generated and the standby time Δt ₀ has elapsed, the power control unit 211 is operated, and the first stage power lower than the power at the time of the process is lower than the power at the time of the process from the high frequency power supply 21 on the source side. (Step S204).

  As a result, as shown in FIGS. 7B and 7D, reflected waves propagate from the load side toward the high-frequency power sources 21 and 31 on both the source side and the bias side. At this time, the power value of the reflected wave propagating to the self side is measured on the bias side (step S304), and on the source side, the power value of the reflected wave measured on the source side is directed toward the bias side. This is output (step S205).

On the bias side, the measurement result of the power value for the reflected wave of itself (FIG. 6, step S304) and the power value of the reflected wave received from the source side (step S305) are the third threshold value and the fourth threshold value, respectively. These values are monitored until the value becomes equal to or less than the threshold value (step S306; NO). Then, when the power value of the reflected wave on the bias side becomes equal to or lower than the third threshold value, and the power value of the reflected wave received from the source side once increases and then becomes lower than the fourth threshold value (step S306). YES), a timing signal is generated, and the power control unit 311 is activated at time T ₃ ′ after the standby time Δt ₀ has elapsed, and power during the process is applied to the lower electrode 41 from the high frequency power supply 31 on the bias side. (Step S307).

Hereinafter, the power value of the reflected wave generated on both the source side and the bias side in this power application operation is measured in real time (step S206), transmitted and received (steps S308 and S207), and monitored (step S208; NO), respectively. Is equal to or lower than the first and second threshold values (step S208; YES), a timing signal is generated, and at time T ₄ ′ after the standby time Δt ₀ has elapsed, this time, Power during the process is applied from the high-frequency power source 21 to the lower electrode 41 (step S209), and the start-up operation related to power supply ends (end). As a result, stable plasma is formed in the processing space 13 and the etching process of the substrate S is started.

  The present embodiment has the following effects. In the etching processing apparatus 1 that sequentially increases the output power of the plurality of high-frequency power sources 21 and 31 step by step when the plasma is started up, the one high-frequency power source 21 and 31 that has been turned in order to increase the output power by one step, At least after the power value of the reflected wave of the other high-frequency power supplies 31 and 21 becomes less than or equal to the threshold value, the output power of the one high-frequency power supply 21 or 31 is increased by one step when the standby time has elapsed. Therefore, for example, in comparison with a method of applying high-frequency power in the next step after waiting for a preset time, the next step is executed before the reflected wave is sufficiently attenuated, and the reflected wave is generated in the circuit of the etching apparatus. It is possible to stably start the etching processing apparatus 1 by preventing the occurrence of a situation in which plasma cannot be formed by propagating in a superimposed manner, while the reflected wave is quickly generated. It enables rapid start running quickly next step without causing useless waiting time when attenuated.

  In this example, the reflected waves of the other high-frequency power sources 31 and 21 are equal to or lower than the threshold value, and the reflected waves of the high-frequency power measured on the self-side that is the one high-frequency power source 21 and 31 are the threshold values. Since the output power is increased by one step after both of the following conditions are satisfied, the etching processing apparatus 1 is stably started even when the timing at which the reflected wave attenuates is switched. be able to.

  Each high frequency power supply unit 2, 3 is provided with a signal transmission path for directly transmitting / receiving (transmitting) the power value of the reflected wave, and the timing signal generators 22, 32 are connected to each high frequency power supply unit 2, 3. Therefore, these high frequency power supply units 2 and 3 can directly control the high frequency power supplies 21 and 31 without using the control unit 100 to increase their outputs. Normally, when the etching processing apparatus 1 is activated, the control unit 100 executes pressure control in the processing container 10 and control of the supply amount of etching gas in parallel, and the load is high. For this reason, if the control unit 100 side performs control for increasing the output of the high-frequency power sources 21 and 31 based on the determination of whether or not the power value of the reflected wave is equal to or lower than the threshold value, and the determination result, these Operation may be delayed. In this respect, each of the high frequency power supply units 2 and 3 can perform these determinations and control specialized to the power supply operation, thereby reducing the burden on the control unit 100 and realizing a quick start-up operation. be able to.

  Here, in the etching processing apparatus 1 shown in FIG. 1, a so-called lower dual frequency type etching processing apparatus 1 in which the high-frequency power units 2 and 3 on both the source side and the bias side are connected to the lower electrode 41 is shown. The connection method of the high-frequency power units 2 and 3 is not limited to this. For example, the so-called top and bottom connecting the high-frequency power supply unit 2 for source to the upper electrode 51 side and connecting the high-frequency power supply unit 3 for bias to the lower electrode 41. The present invention can also be applied to the dual frequency type etching processing apparatus 1.

  Further, the number of high-frequency power sources provided in the etching processing apparatus 1 is not limited to two, and may be three or more. For example, in order to apply a large amount of power for plasma formation, for example, two high frequency power sources S1 and S2 are connected to the lower electrode 41 on the source side, and a high frequency power source B on the bias side is connected to the lower electrode 41 to The case where the frequency-type etching processing apparatus 1 is comprised etc. can be considered.

  In this case, the sequence of increasing the output of each high frequency power source S1, S2, B is three high frequency power sources S1, for example, high frequency power source B → high frequency power source S1 → high frequency power source S2 → high frequency power source B →. The outputs of S2 and B may be increased sequentially, or the output on the bias side and the source side may be increased alternately, such as high frequency power supply B → high frequency power supply S1 and S2 → high frequency power supply B →. . In any sequence, after the measured power value of the reflected wave of the other high-frequency power supply becomes equal to or lower than the threshold value for one high-frequency power supply whose turn has been increased by one step, the one high-frequency power supply The output power can be increased by one step.

  Further, in each of the high-frequency power supply units 2 and 3 shown in FIGS. 3 and 4, when both the power value of the reflected wave of the self and the power value of the reflected wave of the other party are below the preset threshold value The output power of each of the high frequency power supplies 21 and 31 is increased only, but for example, the output is increased by detecting that only the reflected wave on the other side is below a preset threshold value. Also good.

  For example, as already described with reference to FIGS. 7B and 7D, it takes a long time for the reflected wave generated on the high-frequency power source side whose output is increased to attenuate, and the output In general, the reflected wave generated on the other side that does not increase is attenuated in a relatively short time, and in increasing the output on the other side, the other side, that is, the high frequency that increased the output This is because it is often sufficient to monitor the value of the reflected wave generated on the power supply side.

  Furthermore, the method for determining whether or not the power value of the reflected wave is equal to or lower than a preset threshold value is limited to the case where the hardware method shown in FIGS. 3 and 4 is used and a logic circuit is used. Instead, for example, a CPU may be provided in each of the high frequency power supply units 2 and 3 so that the CPU makes a determination in terms of software. In addition, the determination is not limited to the case where each of the high-frequency power supply units 2 and 3 makes these determinations, and the control unit 100 that controls the operation of the entire etching processing apparatus 1 acquires the measurement result of the power value of the reflected wave. Of course, it is possible to increase the outputs of the high-frequency power supplies 21 and 31 by determining whether or not the threshold value has been reached.

  Then, as shown in the embodiment of FIG. 3 and FIG. 4, this determination is performed by transmitting the measurement result of the power value of the reflected wave to the other party as reflected wave information, and on the other party receiving this, It is not limited to the method of determining whether or not the threshold value has been reached, but the threshold at which the power value can increase the output of the other party on the high-frequency power source 21 or 31 side where the power value of the reflected wave is measured. It may be determined whether or not the value is equal to or less than the value, and a determination signal indicating that the power value is equal to or less than the threshold value may be transmitted to the other party as reflected wave information.

  In addition, the plasma processing apparatus provided with a plurality of high-frequency power sources is not limited to the parallel plate type shown in FIG. 1, and for example, an inductively coupled plasma type etching apparatus such as a spiral coil The present invention can also be applied to a case where a high frequency power source is provided for each of the upper electrode and the lower electrode.

  Further, in the above-described embodiment, at the time of plasma start-up, at least one high-frequency power source 21, 31 has the one high-frequency power source 31, 21 after the power value of the reflected wave of the other high-frequency power source 31, 21 becomes equal to or less than a threshold value. Although an example in which the output power of the power supplies 21 and 31 is increased by one stage has been described, the case to which the present invention can be applied is not limited to when plasma is started. For example, as shown in FIG. 8A and FIG. 8B for the purpose of changing the state of the etching processing apparatus 1 such as the plasma formation region in the processing vessel 10 and the adjustment of plasma electron temperature and electron density. When the power applied to each of the source-side and bias-side high-frequency power supply units 2 and 3 is gradually raised from the power during the first process to the power during the second process, for example, with intermediate power interposed therebetween. The present invention can also be applied.

  In contrast to the example shown in FIG. 8, for example, as shown in FIGS. 9A and 9B, for the purpose of changing the state of the etching processing apparatus 1, the source-side and bias-side high-frequency power supply units are provided. When the power applied in steps 2 and 3 is stepped down from the power in the first process to the power in the second process, or one is stepped up and the other is stepped The present invention can also be applied to a case where the output power of a plurality of high-frequency power sources is changed, such as when it is lowered. The change of the operation state in this case includes, for example, the case where the etching processing apparatus 1 is stopped. In this case, the power during the second process shown in FIG. 9 is zero.

  Further, the stepwise change of the output power (starting up and shutting down) is not limited to changing the output of each of the high frequency power supplies 31 and 21 in order. In the case of starting up in more than one stage and then starting up the other side in two or more stages in succession, the power values of the reflected waves of both high frequency power supplies 31 and 21 are below the threshold value. After that, it is recommended to change the output at each stage.

  Furthermore, the processing apparatus of the present invention can be applied to processing for processing an object to be processed using another processing gas such as ashing or CVD (Chemical Vapor Deposition) other than etching processing. Furthermore, the object to be processed is not limited to a square substrate, and may be, for example, a circular semiconductor wafer in addition to an FPD substrate or a solar cell substrate.

It is a vertical side view which shows the whole structure of the plasma processing apparatus which concerns on this Embodiment. It is a block diagram which shows the structural example of the high frequency power supply unit provided in the said plasma processing apparatus. It is explanatory drawing which shows the internal structure of the high frequency power supply unit by the side of a source. It is explanatory drawing which shows the internal structure of the high frequency power supply unit by the side of a bias. It is a 1st flowchart which shows the supply operation | movement of the high frequency electric power at the time of starting of the said plasma processing apparatus. It is a 2nd flowchart which shows the supply operation | movement of the said high frequency electric power. It is explanatory drawing which shows a mode that high frequency electric power is supplied to a plasma processing apparatus in steps by the said supply operation | movement. It is explanatory drawing which shows a mode that high frequency electric power is supplied to a plasma processing apparatus in steps when adjusting a plasma state. It is another explanatory drawing which shows a mode that high frequency electric power is supplied to a plasma processing apparatus in steps when adjusting a plasma state. It is explanatory drawing which shows a mode that high frequency electric power is supplied in steps in the conventional plasma processing apparatus.

Explanation of symbols

S FPD substrate (substrate)
DESCRIPTION OF SYMBOLS 1 Etching processing apparatus 10 Processing container 16 Matching box 100 Control part 101 Control board 161,162
Matching circuit 2 High frequency power supply unit 21 for source High frequency power supply 22 Timing signal generation unit 23 Communication board 211 Power control unit 212 High frequency power supply body 213 Directional coupler 214 Reflected wave wattmeter 215 Traveling wave wattmeters 221 and 224
Comparator 222 Pulse output circuit 223 One-shot multivibrator (OMV)
225 Negative circuit 3 High frequency power supply unit 31 for bias High frequency power supply 32 Timing signal generation unit 33 Communication board 311 Power control unit 312 High frequency power supply body 313 Directional coupler 314 Reflected wave wattmeter 315 Traveling wave wattmeters 321 and 324
Comparator 322 Pulse output circuit 323, 326
OMV
325 Negative circuit 327 OR circuit 41 Lower electrode 51 Upper electrode 54 Process gas supply unit

Claims (9)

A plurality of high-frequency power supplies that output high-frequency waves in the processing container, and the target object in the processing container is processed by plasma, and the plurality of these power- ups are used to start up the plasma or change the plasma state. in the plasma processing apparatus for each stepwise change the output power of the high frequency power source,
A high-frequency power supply unit that is provided for each high-frequency power supply and includes a high-frequency power supply, a power control unit that controls the output of the high-frequency power supply, and a reflected wave measurement unit that measures a power value of a reflected wave reflected by the high-frequency power supply;
Means for determining whether or not the measured power value of the reflected wave of each high-frequency power source is equal to or lower than a threshold value;
Change the output power of other high-frequency power supply other than one high-frequency power supply from one stage to another, and the measured power value of the reflected wave of the other high-frequency power supply generated based on the change is below the threshold value after becoming a plasma processing apparatus, wherein a timing signal for changing the output power of the one of the high-frequency power source when the elapsed preset time and means for providing to the power control unit. The plasma processing apparatus according to claim 1, wherein changing the output power of the one high-frequency power supply increases the output power by one step.   The timing signal includes a condition that the measured power value of the reflected wave of the other high-frequency power source is less than a threshold value and a condition that the measured power value of the reflected wave of the one high-frequency power source is less than or equal to the threshold value. The plasma processing apparatus according to claim 1, wherein the plasma processing apparatus is generated when a preset time has elapsed after both conditions are satisfied. Connected between the high-frequency power supply units, and directly transmits the reflected wave information consisting of the measured power value of the reflected wave or a determination signal indicating that the measured power value is below the threshold value between the high-frequency power supply units. A signal transmission path for
The means for giving the timing signal to the power control unit includes means for generating the timing signal based on the reflected wave information of another high frequency power supply provided in each high frequency power supply unit and sent from the signal transmission path. The plasma processing apparatus according to any one of claims 1 to 3.   The means for giving the timing signal to the power control unit is means for determining whether or not the measured power value of the reflected wave of its own high-frequency power source is equal to or lower than a threshold value, the determination result in this means and the signal transmission path The plasma processing apparatus according to claim 4, further comprising means for generating the timing signal based on reflected wave information of another high-frequency power source sent from.   5. The means for determining whether or not the measured power value of the reflected wave of the high-frequency power source is equal to or less than a threshold value and the means for generating the timing signal are constituted by a logic circuit. Or the plasma processing apparatus of 5. A plurality of high-frequency power supplies that output high-frequency waves in the processing container, and the target object in the processing container is processed by plasma, and the plurality of these power- ups are used to start up the plasma or change the plasma state. method of operating a plasma processing apparatus for changing the output power in each stepwise high frequency power supply,
Measuring the power value of the reflected wave of each high-frequency power supply;
The output power of another high frequency power supply other than one high frequency power supply is changed from one stage to another stage, and the measured power value of the reflected wave of the other high frequency power supply generated based on the change is below the threshold value. Determining whether or not there is,
Include the steps of changing the output power of the one of the high-frequency power source when the measured power value of the reflected wave of said other high-frequency power source after it is determined that falls below the threshold value, passed the preset time A method for operating a plasma processing apparatus. 8. The method of operating a plasma processing apparatus according to claim 7, wherein changing the output power of the one high-frequency power supply increases the output power by one step. Determining whether or not the measured power value of the reflected wave of the one high-frequency power source is a threshold value or less,
The step of changing the output power of the one high-frequency power source includes the condition that the measured power value of the reflected wave of the other high-frequency power source is equal to or lower than a threshold value and the measured power value of the reflected wave of the one high-frequency power source. 9. The method of operating a plasma processing apparatus according to claim 7, wherein the operation is performed when a preset time has elapsed after both of the conditions, i.e., the condition is equal to or less than a threshold value, are satisfied.

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