TWI782133B - Plasma processing apparatus, temperature control method, and temperature control program - Google Patents

Abstract

A heater controller controls power supplied to a heater capable of adjusting the temperature of a placement surface such that the heater reaches a set temperature. A temperature monitor measures the power supplied in the non-ignited state where the plasma is not ignited and in the transient state where the power supplied to the heater decreases after the plasma is ignited, while the power is controlled such that the temperature of the heater becomes constant. A parameter calculator calculates a heat input amount and the thermal resistance by using the power supplied in the non-ignited state and in the transient state to perform a fitting on a calculation model for calculating the power supplied in the transient state. A set temperature calculator calculates the set temperature of the heater at which the wafer reaches the target temperature, using the heat input amount and thermal resistance.

Description

Plasma treatment device, temperature control method and temperature control program

Various aspects and embodiments of the present invention relate to a plasma treatment device, a temperature control method, and a temperature control program.

Conventionally, a plasma processing apparatus is generally known, which uses plasma to perform plasma processing such as etching on an object to be processed such as a semiconductor wafer (hereinafter also referred to as a “wafer”). As far as the plasma processing apparatus is concerned, the temperature of the wafer is an important parameter in the etching process.

Therefore, as far as the plasma processing apparatus is concerned, we propose a method of embedding a temperature-controllable heater into a mounting table on which a wafer is placed, and controlling the temperature of the wafer by the heater. Also, we propose a method of predicting the temperature of a wafer heated by a heater. [Prior Technical Literature] 〔Patent Document〕

[Patent Document 1]: Japanese Unexamined Patent Publication No. 2016-001688 [Patent Document 2]: Japanese Unexamined Patent Publication No. 2009-302390 [Patent Document 3]: Japanese Patent Laid-Open No. 2017-011169

[Problem to be solved by the invention]

However, in plasma processing, there is heat input from the plasma towards the wafer. Therefore, the plasma processing apparatus may not be able to accurately control the temperature of the wafer being plasma processed to the target temperature. [How to solve the problem]

In one embodiment, the plasma processing device disclosed in this specification includes a mounting table, a heater control unit, a measurement unit, a parameter calculation unit, and a set temperature calculation unit. The mounting table is provided with a heater capable of adjusting the temperature of the mounting surface on which the object to be processed, which is the target of the plasma treatment, is mounted. The heater control unit controls the electric power supplied to the heater so that the heater becomes the set temperature. In the measurement part, the heater control part controls the power supply to the heater so that the temperature of the heater becomes constant, and the unignited state of the unignited plasma is measured and the power supply to the heater decreases after the plasma is ignited. The power supply in the transition state. The parameter calculation unit uses the non-ignition measured by the measurement unit for the calculation model that uses the heat input from the plasma and the thermal resistance between the object to be processed and the heater as parameters and calculates the power supply in the transition state. The power supply in the state and transition state is fitted to calculate the heat and thermal resistance. The set temperature calculation unit calculates the set temperature of the heater to bring the object to be processed to a target temperature using the heat input and thermal resistance calculated by the parameter calculation unit. [Effect of the invention]

According to one aspect of the plasma processing apparatus disclosed in this specification, the effect that the temperature precision of the object to be processed during plasma processing can be controlled well to the target temperature is exhibited.

[Preferable form of implementing the invention]

Hereinafter, embodiments of the plasma treatment device, temperature control method, and temperature control program disclosed in this application will be described in detail with reference to the drawings. In addition, in each drawing, the same code|symbol is attached|subjected to the same or equivalent part. In addition, the disclosed invention is not limited by embodiment. The respective embodiments can be appropriately combined within a range that does not cause conflicts in processing contents.

(first embodiment) 〔Configuration of plasma processing equipment〕 First, the configuration of the plasma processing apparatus 10 of the embodiment will be described. Fig. 1 schematically shows a plasma treatment apparatus according to a first embodiment. FIG. 1 schematically shows the structure in longitudinal section of a plasma processing apparatus 10 according to a first embodiment. The plasma processing device 10 shown in FIG. 1 is a capacitively coupled parallel plate plasma etching device. This plasma processing apparatus 10 includes a substantially cylindrical processing container 12 . The processing container 12 is made of aluminum, for example. In addition, the surface of the processing container 12 is anodized.

A mounting table 16 is provided in the processing container 12 . The stage 16 includes an electrostatic chuck 18 and a base 20 . The upper surface of the electrostatic chuck 18 is defined as a loading surface on which an object to be processed, which is a target of plasma processing, is placed. In the present embodiment, the wafer W is placed on the upper surface of the electrostatic chuck 18 as an object to be processed. The base 20 has a substantially disc shape, and its main part is made of, for example, a conductive metal such as aluminum. This submount 20 constitutes a lower electrode. The base station 20 is supported by the support unit 14 . The support portion 14 is a cylindrical member extending from the bottom of the processing container 12 .

The base station 20 is electrically connected to the first radio frequency power source HFS via the matching unit MU1. The first radio frequency power supply HFS is used to generate radio frequency power for plasma generation, and generates a frequency of 27-100 MHz, and in one example generates radio frequency power of 40 MHz. Thereby, plasma is generated directly on the submount 20 . The matching unit MU1 has a circuit for matching the output impedance of the first radio frequency power source HFS with the input impedance of the load side (base station 20 side).

Moreover, the base station 20 is electrically connected to the second radio frequency power supply LFS via the matching unit MU2. The second RF power source LFS generates RF power (RF bias power) for pulling ions into the wafer W, and supplies the RF bias power to the base 20 . Thereby, a bias potential is generated on the base 20 . The frequency of the radio frequency bias power is a frequency in the range of 400 kHz to 13.56 MHz, and in one example, it is 3 MHz. The matching unit MU2 has a circuit for matching the output impedance of the second radio frequency power supply LFS with the input impedance of the load side (base station 20 side).

An electrostatic chuck 18 is disposed on the base 20 . The electrostatic chuck 18 attracts the wafer W by electrostatic force such as Coulomb force, and holds the wafer W. The electrostatic chuck 18 has an electrode E1 for electrostatic adsorption in a main body made of ceramics. The electrode E1 is electrically connected to the DC power source 22 through the switch SW1. The suction force for holding the wafer W depends on the value of the DC voltage applied from the DC power supply 22 .

A focus ring FR is provided on the upper surface of the base 20 and around the electrostatic chuck 18 . The focus ring FR is set to improve the uniformity of plasma treatment. The focus ring FR is made of a material suitably chosen for the plasma treatment to be performed, for example silicon or quartz.

A refrigerant channel 24 is formed inside the base 20 . The refrigerant is supplied to the refrigerant flow path 24 from a quenching unit provided outside the processing container 12 through a pipe 26 a. The refrigerant supplied to the refrigerant flow path 24 returns to the quenching unit through the pipe 26b. In addition, details of the stage 16 including the base 20 and the electrostatic chuck 18 will be described later.

An upper electrode 30 is provided in the processing container 12 . The upper electrode 30 is arranged to face the base 20 above the mounting table 16 , and the base 20 and the upper electrode 30 are arranged approximately parallel to each other.

The upper electrode 30 is supported by the upper portion of the processing chamber 12 via an insulating shielding member 32 . The upper electrode 30 may include an electrode plate 34 and an electrode support 36 . The electrode plate 34 faces the processing space S and provides a plurality of gas ejection holes 34a. The electrode plate 34 can be made of a low-resistance conductor or semiconductor with little Joule heat.

The electrode support 36 supports the electrode plate 34 in a detachable manner, and may be made of a conductive material such as aluminum, for example. This electrode support 36 may have a water-cooled structure. A gas diffusion chamber 36 a is provided inside the electrode support 36 . Extending downward from the gas diffusion chamber 36a are a plurality of gas flow holes 36b communicating with the gas injection holes 34a. In addition, the electrode support 36 is formed with a gas introduction port 36c for introducing a process gas into the gas diffusion chamber 36a, and a gas supply pipe 38 is connected to the gas introduction port 36c.

The gas supply pipe 38 is connected to a gas source group 40 via a valve group 42 and a flow controller group 44 . The valve group 42 has a plurality of on-off valves, and the flow controller group 44 has a plurality of flow controllers such as mass flow controllers. In addition, the gas source group 40 has gas sources for plural types of gases necessary for plasma processing. A plurality of gas sources of the gas source group 40 are connected to the gas supply pipe 38 through corresponding on-off valves and corresponding mass flow controllers.

In the plasma processing apparatus 10 , one or more gases from one or more gas sources selected from among the plurality of gas sources in the gas source group 40 are supplied to the gas supply pipe 38 . The gas supplied to the gas supply pipe 38 reaches the gas diffusion chamber 36a, and is discharged into the processing space S through the gas flow hole 36b and the gas discharge hole 34a.

Moreover, as shown in FIG. 1 , the plasma processing apparatus 10 may further include a ground conductor 12a. The ground conductor 12 a is a substantially cylindrical ground conductor, and is provided to extend from the side wall of the processing container 12 to a position higher than the height of the upper electrode 30 .

In addition, in the plasma processing apparatus 10 , a deposit barrier 46 is detachably provided along the inner wall of the processing container 12 . In addition, a deposit barrier 46 is also provided on the outer periphery of the support portion 14 . The deposit barrier 46 prevents etching by-products (deposits) from adhering to the processing container 12, and can be formed by coating ceramics such as Y ₂ O ₃ on an aluminum material.

On the bottom side of the processing container 12 , an exhaust plate 48 is provided between the support portion 14 and the inner wall of the processing container 12 . The exhaust plate 48 can be formed by coating an aluminum material with ceramics such as Y ₂ O ₃ , for example. Below this exhaust plate 48, the processing container 12 is provided with an exhaust port 12e. An exhaust device 50 is connected to the exhaust port 12e via an exhaust pipe 52 . The exhaust device 50 has a vacuum pump such as a turbomolecular pump, and can depressurize the inside of the processing container 12 to a desired vacuum degree. Furthermore, a loading and unloading port 12 g for the wafer W is provided on the side wall of the processing container 12 , and the loading and unloading port 12 g can be opened and closed by a gate valve 54 .

The operation of the plasma processing apparatus 10 configured as described above is generally controlled by the control unit 100 . The control unit 100 is, for example, a computer, and controls various parts of the plasma processing apparatus 10 . The operation of the plasma processing apparatus 10 is generally controlled by the control unit 100 .

〔Configuration of the mounting table〕 Next, the mounting table 16 will be described in detail. Fig. 2 is a plan view showing the mounting table of the first embodiment. As mentioned above, the stage 16 has the electrostatic chuck 18 and the base 20 . The electrostatic chuck 18 has a body part 18m made of ceramics. The body portion 18m has a substantially disc shape. The main body portion 18m provides a mounting area 18a and an outer peripheral area 18b. The loading area 18a is a substantially circular area in plan view. Wafer W is placed on the upper surface of this loading region 18 a. That is, the upper surface of the mounting region 18 a functions as a mounting surface on which the wafer W is mounted. The diameter of the mounting area 18 a is substantially the same as the diameter of the wafer W or slightly smaller than the diameter of the wafer W. The outer peripheral area 18b is an area surrounding the mounting area 18a, and extends in a roughly ring shape. In this embodiment, the upper surface of the outer peripheral region 18b is positioned lower than the upper surface of the mounting region 18a.

As shown in FIG. 2 , the electrostatic chuck 18 has an electrode E1 for electrostatic adsorption in a mounting region 18 a. This electrode E1 is connected to the DC power supply 22 through the switch SW1 as described above.

In addition, a plurality of heaters HT are provided in the mounting region 18a and below the electrode E1. In this embodiment, the mounting area 18a is divided into a plurality of divided areas, and heaters HT are provided in each divided area. For example, as shown in FIG. 2 , a plurality of heaters HT are provided in a circular area at the center of the mounting area 18 a and a plurality of concentric annular areas surrounding the circular area. In addition, a plurality of heaters HT are arranged and arranged in the circumferential direction in each of the plurality of ring-shaped regions. In addition, the division method of the division area shown in FIG. 2 is an example, and it is not limited to this. The loading area 18a can also be divided into more divided areas. For example, the mounting area 18a may be divided into divisional areas whose angular range becomes smaller and radial width becomes narrower as it gets closer to the outer periphery. The heaters HT are individually connected to heater power supplies HP shown in FIG. 1 via unillustrated wiring provided on the outer peripheral portion of the base 20 . The heater power supply HP supplies individually adjusted electric power to each heater HT based on the control of the control unit 100 . Thereby, the heat generated by each heater HT is individually controlled, and the temperatures of the plurality of divided regions in the mounting region 18 a are individually adjusted.

The heater power supply HP is provided with a power detection part PD which detects the power supplied to each heater HT. Moreover, the electric power detection part PD may be provided in the wiring which flows the electric power from heater power supply HP to each heater HT separately from heater power supply HP. The electric power detection part PD detects the electric power supplied to each heater HT. For example, the electric power detection part PD detects the electric power supplied to each heater HT as electric power [W]. The heater HT generates heat in response to electric power. Therefore, the electric power supplied to the heater HT represents heater electric power. The power detection part PD notifies the control part 100 of power data which detects and displays the power supplied to each heater HT.

Moreover, the mounting table 16 is provided with a temperature sensor (not shown) which can respectively detect the temperature of the heater HT in each divided area of the mounting area 18a. The temperature sensor can also be an element that is different from the heater HT and can measure the temperature. In addition, the temperature sensor can also be arranged on the wiring for the electric power flowing to the heater HT, and it can be obtained by measuring the voltage and current of the heater HT by using the characteristic that the resistance of the main metal increases in proportion to the temperature rise. Resistance value to detect temperature. The sensor values detected by each temperature sensor are sent to the temperature measuring device TD. The temperature measuring device TD measures the temperature of each division|segmentation area|region of the mounting area 18a from each sensor value. The temperature measuring device TD notifies the control unit 100 of temperature data indicating the temperature of each divided area of the mounting area 18a.

Furthermore, a heat transfer gas such as He gas may be supplied between the upper surface of the electrostatic chuck 18 and the back surface of the wafer W through a heat transfer gas supply mechanism and a gas supply line not shown.

[Configuration of the control unit] Next, the control unit 100 will be described in detail. Fig. 3 is a block diagram showing a schematic configuration of a control unit for controlling the plasma processing apparatus according to the first embodiment. The control unit 100 is provided with an external interface 101 , a process controller 102 , a user interface 103 , and a memory unit 104 .

The external interface 101 can communicate with various parts of the plasma processing apparatus 10 to input and output various data. For example, the external interface 101 receives power data showing power supplied to each heater HT from the power detection part PD. Moreover, the external interface 101 inputs the temperature data which shows the temperature of each divided area|region of the mounting area 18a from the temperature measuring device TD. Moreover, the external interface 101 outputs control data for controlling the supply power supplied to each heater HT to the heater power supply HP.

The process controller 102 has a CPU (Central Processing Unit, central processing unit) and controls each part of the plasma processing apparatus 10 .

The user interface 103 is composed of a keyboard for the program manager to input commands for managing the plasma processing apparatus 10, a display for visually displaying the working status of the plasma processing apparatus 10, and the like.

The memory unit 104 stores control programs (software) for realizing various processes performed by the plasma processing device 10 under the control of the process controller 102, formulas storing processing condition data, etc., and related devices necessary for plasma processing and process parameters, etc. In addition, recipes such as control programs and processing condition data can be stored in computer-readable computer recording media (such as hard disks, DVDs, etc., floppy disks, semiconductor memories, etc.), or from other devices such as It can be connected and used by transmission at any time through a dedicated line.

The process controller 102 has an internal memory for storing programs or data, reads the control program stored in the memory unit 104, and executes the processing of the read control program. The process controller 102 functions as various processing units by controlling program operation. For example, the process controller 102 has the functions of a heater control unit 102a, a measurement unit 102b, a parameter calculation unit 102c, a set temperature calculation unit 102d, and a warning unit 102e. In addition, in the plasma processing apparatus 10 of this embodiment, the process controller 102 has the functions of a heater control unit 102a, a measurement unit 102b, a parameter calculation unit 102c, a set temperature calculation unit 102d, and a warning unit 102e. It is described as an example, but the functions of heater control unit 102a, measurement unit 102b, parameter calculation unit 102c, set temperature calculation unit 102d, and warning unit 102e can also be distributed among multiple controllers.

However, in the plasma processing, the progress of the processing varies depending on the temperature of the wafer W. For example, during plasma etching, the etching progress rate varies depending on the temperature of the wafer W. Therefore, in the plasma processing apparatus 10, it is preferable to control the temperature of the wafer W to a target temperature by each heater HT.

However, in the plasma processing, heat is absorbed from the plasma toward the wafer W. As shown in FIG. Therefore, the plasma processing apparatus 10 may not be able to accurately control the temperature of the wafer W being plasma processed to the target temperature.

The flow of energy affecting the temperature of the wafer W will be described. Figure 4 schematically shows the flow of energy affecting the temperature of the wafer. FIG. 4 schematically shows a wafer W, a stage 16 including an electrostatic chuck (ESC) 18 . The example of FIG. 4 shows the flow of energy that affects the temperature of the wafer W in one of the divided regions of the mounting region 18 a of the electrostatic chuck 18 . The mounting table 16 has an electrostatic chuck 18 and a base 20 . The electrostatic chuck 18 and the base 20 are bonded by an adhesive layer 19 . A heater HT is provided inside the mounting area 18 a of the electrostatic chuck 18 . A refrigerant channel 24 through which the refrigerant flows is formed inside the base 20 .

The heater HT generates heat in response to the electric power supplied from the heater power supply HP, and raises its temperature. FIG. 4 shows the electric power supplied to the heater HT as heater power _Ph . Also, the heater HT generates a calorific value (heat flux) q _h per unit area obtained by dividing the heater power Ph _h by the area A of the area where the heater HT is installed in the electrostatic chuck 18 .

Also, when plasma processing is performed, the temperature of the wafer W rises due to heat from the plasma. FIG. 4 shows the heat flux q _p from the plasma obtained by dividing the heat input from the plasma into the wafer W by the area of the wafer W per unit area.

It is well known that the heat input from the plasma is primarily proportional to the product of: the amount of ions in the plasma impinging on the wafer W; and the bias voltage used to pull the ions in the plasma into the wafer W potential. The amount of ions in the plasma irradiated to the wafer W is proportional to the electron density of the plasma. The electron density of the plasma is proportional to the power of the RF power HFS from the first RF power source HFS applied during plasma generation. Also, the electron density of the plasma depends on the pressure in the processing chamber 12 . The bias potential for pulling ions in the plasma into the wafer W is proportional to the power of the RF power LFS from the second RF power LFS applied in generating the bias potential. Also, the bias potential used to pull ions in the plasma into the wafer W depends on the pressure in the processing vessel 12 . In addition, when the radio frequency power LFS is not applied to the mounting table 12 , ions are pulled into the mounting table by the potential difference between the plasma potential (Plasma Potential) generated during plasma generation and the mounting table 12 .

In addition, the heat input from plasma includes heating caused by plasma luminescence, irradiation of wafer W by electrons or free radicals in plasma, surface reaction on wafer W caused by ions and free radicals, etc. . These components also depend on the power or pressure of the AC power. The heat input from the plasma also depends on device parameters related to plasma generation, such as the distance between the mounting table 16 and the upper electrode 30 , and the type of gas supplied to the processing space S.

The heat transmitted to the wafer W is transmitted to the electrostatic chuck 18 . Here, not all the heat of the wafer W is transmitted to the electrostatic chuck 18 , but the heat is transmitted to the electrostatic chuck 18 according to the difficulty of heat transmission such as the degree of contact between the wafer W and the electrostatic chuck 18 . The difficulty of heat transfer, that is, the thermal resistance, is inversely proportional to the cross-sectional area facing the heat transfer direction. Therefore, FIG. 4 shows the heat transfer difficulty from the wafer W to the surface of the electrostatic chuck 18 as the thermal resistance R _th ·A per unit area between the wafer W and the surface of the electrostatic chuck 18 . In addition, A is the area of the area where the heater HT is provided. R _th is the thermal resistance of the entire area where the heater HT is installed. Moreover, FIG. 4 shows the heat input from the wafer W to the surface of the electrostatic chuck 18 as the heat flux q per unit area from the wafer W to the surface of the electrostatic chuck 18 . In addition, the thermal resistance R _th ·A per unit area between the wafer W and the surface of the electrostatic chuck 18 depends on the surface state of the electrostatic chuck 18 and the DC voltage applied from the DC power supply 22 to hold the wafer W. value, and the pressure of the heat transfer gas supplied between the upper surface of the electrostatic chuck 18 and the back surface of the wafer W. In addition, the thermal resistance R _th ·A also depends on device parameters related to thermal resistance or thermal conductivity.

The heat transmitted to the surface of the electrostatic chuck 18 increases the temperature of the electrostatic chuck 18 and is further transmitted to the heater HT. FIG. 4 shows the heat input from the surface of the electrostatic chuck 18 to the heater HT as the heat flux q _c per unit area from the surface of the electrostatic chuck 18 to the heater HT.

On the other hand, the base 20 is cooled by the refrigerant flowing in the refrigerant channel 24 and cools the electrostatic chuck 18 that it contacts. At this time, FIG. 4 shows the heat dissipation from the back of the electrostatic chuck 18 to the base 20 through the adhesive layer 19 as the heat flux q _sus per unit area from the back of the electrostatic chuck 18 to the base 20 . Thereby, the heater HT is cooled by radiating heat, and the temperature is lowered.

When the temperature of the heater HT is controlled to be constant, among the heaters HT, the following is an equal state: the sum of the heat input amount transmitted to the heater HT and the heat generation amount generated in the heater HT; and The amount of heat dissipated from the heater HT. For example, in the unignited state of the unignited plasma, the amount of heat generated in the heater HT is equal to the amount of heat released from the heater HT. Figure 5A schematically shows the flow of energy in the unignited state. In the example of FIG. 5A , the heat of “100” is dissipated from the heater HT by cooling the base 20 . For example, when the temperature of the heater HT is controlled to be constant, the heater HT generates heat of "100" from the heater power supply HP due to the heater power _Ph .

On the other hand, for example, in the ignited state of the ignited plasma, the sum of the heat absorbed into the heater HT and the heat generated in the heater HT is equal to the amount of heat released from the heater HT. Figure 5B schematically shows the flow of energy in the ignited state. Here, the ignition state has a transition state and a steady state. The transition state is, for example, a state in which the heat input to the wafer W or the electrostatic chuck 18 is greater than the heat dissipation, and the temperature of the wafer W or the electrostatic chuck 18 tends to increase with time. The stable state is a state in which the heat input and heat dissipation of the wafer W or the electrostatic chuck 18 are equal, and the temperature of the wafer W or the electrostatic chuck 18 disappears over time, and the temperature is approximately constant.

In the example of FIG. 5B , the heat of “100” is also dissipated from the heater HT by cooling the base 20 . In the ignited state, the temperature of the wafer W rises due to the heat from the plasma until the wafer W reaches a stable state. Heat is transferred from the wafer W to the heater HT via the electrostatic chuck 18 . As described above, when the temperature of the heater HT is controlled to be constant, the amount of heat entering the heater HT and the amount of heat dissipating from the heater HT are in an equal state. The amount of heat required by the heater HT to maintain a constant temperature of the heater HT is reduced. Therefore, the electric power supplied to the heater HT is reduced.

For example, in FIG. 5B , it is defined as an example of "transition state", and heat of "80" is transmitted from the plasma to the wafer W. The heat transmitted to the wafer W is transmitted to the electrostatic chuck 18 . In addition, when the temperature of the wafer W is not in a steady state, a part of the heat transmitted to the wafer W contributes to an increase in the temperature of the wafer W. The amount of heat to increase the temperature of the wafer W depends on the heat capacity of the wafer W. Therefore, “60” of the “80” heat transferred from the plasma to the wafer W is transferred from the wafer W to the surface of the electrostatic chuck 18 . The heat transmitted to the surface of the electrostatic chuck 18 is transmitted to the heater HT. In addition, when the temperature of the electrostatic chuck 18 is in an unstable state, part of the heat transmitted to the surface of the electrostatic chuck 18 acts on an increase in the temperature of the electrostatic chuck 18 . The heat of temperature increase acting on the electrostatic chuck 18 depends on the heat capacity of the electrostatic chuck 18 . Therefore, "40" of the heat "60" transmitted to the surface of the electrostatic chuck 18 is transmitted to the heater HT. Therefore, when the temperature of the heater HT is controlled to be constant, the heat of "60" is supplied to the heater HT from the heater power supply HP by the heater power _Ph .

Also, in FIG. 5B, in the "steady state", heat of "80" is transmitted from the plasma to the wafer W. The heat transmitted to the wafer W is transmitted to the electrostatic chuck 18 . In addition, when the temperature of the wafer W is in a stable state, the amount of heat entering the wafer W is equal to the heat output. Therefore, the heat transferred from the plasma to "80" of the wafer W is transferred from the wafer W to the surface of the electrostatic chuck 18 . The heat transmitted to the surface of the electrostatic chuck 18 is transmitted to the heater HT. When the temperature of the electrostatic chuck 18 is in a steady state, the heat input and output heat of the electrostatic chuck 18 are equal. Therefore, the heat transferred to "80" on the surface of the electrostatic chuck 18 is transferred to the heater HT. Therefore, when the temperature of the heater HT is controlled to be constant, the heat of "20" is supplied to the heater HT from the heater power supply HP by the heater power _Ph .

As shown in FIG. 5A and FIG. 5B , the power supplied to the heater HT is lower in the lit state than in the unlit state. In addition, in the ignition state, the electric power supplied to the heater HT is reduced until a steady state is reached.

FIG. 6 shows an example of changes in the temperature of the wafer W and the power supplied to the heater HT. FIG. 6(A) shows that there is a change in the temperature of the wafer W. FIG. 6(B) shows changes in the electric power supplied to the heater HT. The example in FIG. 6 shows the results of controlling the temperature of the heater HT to be constant, igniting the plasma from the unignited state of the unignited plasma, and measuring the temperature of the wafer W and the power supplied to the heater HT. The temperature of the wafer W is measured using a wafer for temperature measurement such as Etch Temp sold by KLA-Tencor. The wafers used for this temperature measurement are expensive. Therefore, at the mass production site, if the wafer for temperature measurement is used to adjust the temperature of each heater HT of the plasma processing apparatus 10, the cost will increase. In addition, at the mass production site, if the wafer for temperature measurement is used to adjust the temperature of each heater HT of the plasma processing apparatus 10, the production efficiency will decrease.

The period T1 in FIG. 6 is the unignited state of the unignited plasma. During the period T1, the electric power supplied to the heater HT is constant. The period T2 in FIG. 6 is the ignited state of the ignited plasma, and is a transitional state. During the period T2, the electric power supplied to the heater HT is reduced. Also, during the period T2, the temperature of the wafer W rises to a constant temperature. The period T3 in FIG. 6 is the ignited state of the ignited plasma. During the period T3, the temperature of the wafer W is constant and in a steady state. When the electrostatic chuck 18 is also in a stable state, the electric power supplied to the heater HT is approximately constant, and the variation of the downward trend is stable. The period T4 in FIG. 6 is an unignited state in which the plasma is extinguished. During the period T4, since the heat input from the plasma to the wafer W disappears, the temperature of the wafer W decreases, and the power supplied to the heater HT increases.

The decreasing tendency of the electric power supplied to the heater HT in the transitional state shown in the period T2 of FIG. Variety.

Figure 7 schematically shows the flow of energy in the ignited state. In addition, FIG. 7 is an example of a transition state. For example, in FIG. 7 , in the example of "input heat: small, thermal resistance: small", heat of "80" is transmitted from the plasma to the wafer W. "60" of the "80" of heat transferred from the plasma to the wafer W is transferred from the wafer W to the surface of the electrostatic chuck 18 . And, the heat of "40" among the heat of "60" transmitted to the surface of the electrostatic chuck 18 is transmitted to the heater HT. For example, when the temperature of the heater HT is controlled to be constant, the heat of "60" is supplied to the heater HT by the heater power _Ph from the heater power supply HP.

In addition, in FIG. 7 , in the example of "input heat: large, thermal resistance: small", heat of "100" is transmitted from the plasma to the wafer W. "80" of the "100" heat transferred from the plasma to the wafer W is transferred from the wafer W to the surface of the electrostatic chuck 18 . And, "60" of the heat of "80" transmitted to the surface of the electrostatic chuck 18 is transmitted to the heater HT. For example, when the temperature of the heater HT is controlled to be constant, the heat of "40" is supplied to the heater HT by the heater power _Ph from the heater power supply HP.

In addition, in FIG. 7, in the example of "heat input: small, thermal resistance: large", heat of "80" is transmitted from the plasma to the wafer W. "40" of the "80" heat transferred from the plasma to the wafer W is transferred from the wafer W to the surface of the electrostatic chuck 18 . The heat of "20" among the heat of "40" transmitted to the surface of the electrostatic chuck 18 is transmitted to the heater HT. For example, when the temperature of the heater HT is controlled to be constant, the heat of "80" is supplied to the heater HT from the heater power supply HP by the heater power _Ph .

As described above, when the temperature of the heater HT is controlled to be constant, the heater power _Ph changes due to the heat input from the plasma to the wafer W and the thermal resistance between the wafer W and the surface of the electrostatic chuck 18. . Therefore, the decreasing tendency of the electric power supplied to the heater HT during the period T2 shown in FIG. And change. Therefore, in the graph of the electric power supplied to the heater HT during the period T2, the heat input from the plasma to the wafer W and the thermal resistance between the wafer W and the surface of the electrostatic chuck 18 can be modeled as parameters. . That is, in terms of the change of the electric power supplied to the heater HT during the period T2, the amount of heat input from the plasma to the wafer W and the thermal resistance between the wafer W and the surface of the electrostatic chuck 18 can be used as parameters. Expression to model.

In this embodiment, the variation of the electric power supplied to the heater HT during the period T2 shown in FIG. 6(B) is modeled as a formula per unit area. For example, the calorific value q _h per unit area from the heater HT when there is heat flux from the plasma is represented by the following formulas (2)-(4), and when there is no heat flux from the plasma The calorific value q _h0 per unit area from the heater HT in the steady state, and the thermal resistance R _thc ·A per unit area between the surface of the electrostatic chuck 18 and the heater. The heat flux q _p per unit area from the plasma to the wafer W, and the thermal resistance R _th ·A per unit area between the wafer W and the surface of the electrostatic chuck 18 are used as parameters, and using In the case of a ₁ , a ₂ , a ₃ , λ ₁ , λ ₂ , τ ₁ , τ ₂ expressed by the following formulas (5)-(11), the heat flux from the plasma per unit area The calorific value q _h from the heater HT can be represented by the following formula (1).

[Equation 1]

Here, _Ph is the heater power [W] when there is a heat flux from the plasma. P _h0 is the heater power [W] in the steady state without heat flux from the plasma. q _h is the calorific value [W/m ² ] of the heater HT per unit area when there is a heat flux from the plasma. q _h0 is the calorific value [W/m ² ] of the heater HT per unit area in the steady state when there is no heat flux from the plasma. q _p is the heat flux [W/m ² ] per unit area from the plasma to the wafer W. R _th ·A is the thermal resistance [K·m ² /W] per unit area between the wafer W and the surface of the electrostatic chuck 18 . R _thc ·A is the thermal resistance [K·m ² /W] per unit area between the surface of the electrostatic chuck 18 and the heater. A is the area [m ² ] of the area where the heater is installed. ρ _w is the density of the wafer W [kg/m ³ ]. C _w is the heat capacity per unit area of wafer W [J/K·m ² ]. z _w is the thickness [m] of the wafer W. ρ _c is the density [kg/m ³ ] of the ceramics in which the electrostatic chuck 18 is formed. C _c is the heat capacity per unit area [J/K·m ² ] of the ceramics made of the electrostatic chuck 18 . z _c is the distance [m] from the surface of the electrostatic chuck 18 to the heater HT. κ _c is the thermal conductivity [W/K·m] of the ceramic made of the electrostatic chuck 18 . t is the elapsed time [sec] from the time when the plasma is ignited.

Even for a ₁ shown in Equation (5), 1/a ₁ is a time constant that shows the difficulty of heating the wafer W. Furthermore, even for a ₂ shown in the formula (6), 1/a ₂ is a time constant indicating the difficulty of heating and warming the electrostatic chuck 18 . Also, for a ₃ shown in Equation (7), 1/a ₃ is a time constant indicating the difficulty of heat penetration and warming of the electrostatic chuck 18 .

The area A of the heater HT, the density ρ _w of the wafer W, the heat capacity C _w per unit area of the wafer W, and the Thickness z _w , density ρ _c of the ceramic made of the electrostatic chuck 18 , heat capacity C _c per unit area of the ceramic made of the electrostatic chuck 18 , calculated from the surface of the electrostatic chuck 18 to the heater HT The distance z _c , and the thermal conduction κ _c of the ceramic that will constitute the electrostatic chuck 18 . R _thc・A is determined in advance by the formula (4) from the heat conduction κ _c and the distance z _c .

The plasma processing device 10 can be used to measure the heater power P _h with the heat flux from the plasma and without the heat flux from the plasma for each elapsed time t counted from the ignition of the plasma The heater power P _h0 in the steady state of the time. Moreover, as shown in formulas (2) and (3), dividing each of the obtained heater power _{Ph and heater power P h0 by} the area A of the heater HT can be used to obtain the The calorific value q _h per unit area from the heater HT at the time of the heat flux, and the calorific value q _h0 per unit area from the heater HT in the steady state when there is no heat flux from the plasma .

Moreover, the measurement results can be used to fit the formula (1), so as to obtain the heat flux q _p per unit area from the plasma to the wafer W and the distance between the wafer W and the surface of the electrostatic chuck 18 The thermal resistance R _th ·A per unit area.

In addition, regarding the graph of the temperature of the wafer W during the period T2 shown in FIG. Thermal resistance is modeled as a parameter. In this embodiment, the change in the temperature of the wafer W during the period T2 is modeled into a formula per unit area. For example, when the heat flux q _p per unit area from the plasma to the wafer W, the thermal resistance R _th ·A per unit area between the wafer W and the surface of the electrostatic chuck 18 are used as parameters, and When a ₁ , a ₂ , a ₃ , λ ₁ , λ ₂ , τ ₁ , τ ₂ shown in formulas (5)-(11) are used, the temperature T _W [°C] of the wafer W can be expressed as follows Formula (12).

[Equation 2]

Here, T _W is the temperature [° C.] of the wafer W. _Th is controlled as the temperature [°C] of the fixed heater HT.

The temperature _Th of the heater can be obtained from the conditions when the temperature of the wafer W is actually controlled to be constant.

Using the measurement results to fit the formula (1) to obtain the heat flux q _p and the thermal resistance R _th ·A, the temperature T _W of the wafer W can be calculated by the formula (12).

In the case where the elapsed time t is sufficiently longer than the time constants τ ₁ and τ ₂ represented by the formulas (10) and (11), that is, when calculating the transition from the transition state of the period T2 to the period T3 in Fig. 6 In the case where the temperature T _W of the wafer W after the steady state becomes the temperature _Th of the heater HT at the target temperature, the formula (12) can be omitted as in the following formula (13).

[Equation 3]

For example, the temperature T _W of the wafer W can be obtained from the temperature _Th of the heater, the heat flux q _p , the thermal resistances R _th ·A, and R _thc ·A by the formula (13).

Return to Figure 3. The heater control unit 102a controls the temperature of each heater HT. For example, the heater control unit 102a outputs control data indicating the power supply to each heater HT to the heater power supply HP to control the power supply from the heater power supply HP to each heater HT, thereby controlling each heater HT temperature.

At the time of plasma processing, the heater control part 102a sets the target set temperature of each heater HT. For example, the heater control unit 102a sets the temperature of the target wafer W to the set temperature of the heater HT in each divided area of each loading area 18a. The target temperature of the wafer W is, for example, the temperature at which the accuracy of plasma etching for the wafer W is optimal.

The heater control part 102a controls the electric power supplied to each heater HT so that each heater HT becomes the set temperature which was set at the time of plasma processing. For example, the heater control unit 102a compares the temperature of each divided area of the mounting area 18a displayed in the temperature data input to the external interface 101 with the set temperature of the divided area for each divided area, and specifies the temperature of each divided area. A divided area with a lower temperature than the set temperature, and a divided area with a higher temperature than the set temperature. The heater control unit 102a outputs to the heater power supply HP control data that increases the power supply to the divisional area with a lower temperature than the set temperature and increases the power supply to the divisional area with a higher temperature than the set temperature. The power supply is reduced.

The measurement part 102b measures the power supplied to each heater HT using the power supplied to each heater HT displayed by the power data input to the external interface 101 . For example, the measurement unit 102b controls the power supplied to each heater HT by the heater control unit 102a so that the temperature of each heater HT becomes constant, and measures the unignited state of the unignited plasma and the self-ignited plasma. The change from the start to the decreasing trend of the power supply to each heater HT is the power supply to each heater HT in a stable transient state.

The heater control part 102a controls the electric power supplied to each heater HT so that each heater HT may become a fixed set temperature at the time of plasma processing. The measurement unit 102b measures the plasma non-ignition before the start of the plasma treatment when the heater control unit 102a controls the power supply to each heater HT so that the temperature of each heater HT becomes a fixed set temperature. Power supply to each heater HT in the state. In addition, the measurement unit 102b measures the power supply to each heater HT in a transitional state in which the fluctuation of the power supply to each heater HT is stable since the plasma is ignited. The electric power supplied to each heater HT in the non-ignited state may be measured at least one in each heater HT, and may be measured a plurality of times, and an average value may be used as the electric power supplied in the non-lit state. The electric power supplied to each heater HT in the transient state may be measured twice or more. The timing of measuring the power supply is suitable for the time when the power supply has a great downward trend. Also, in the case of a small number of measurements, it is appropriate to measure at intervals of more than a predetermined period. In this embodiment, the measuring part 102b measures the electric power supplied to each heater HT at a predetermined cycle (for example, 0.1-second cycle) during a plasma processing period. Thereby, the electric power supplied to each heater HT in a plurality of transient states is measured.

The measurement part 102b measures the electric power supplied to each heater HT in the non-ignition state and the transition state in a predetermined cycle. For example, the measurement unit 102b measures the temperature of each heater HT in the unignited state and the transition state each time the wafer W is replaced and the replaced wafer W is placed on the mounting table 16 for plasma processing. to supply electricity. In addition, for example, the parameter calculation unit 102c may also measure the power supplied to each heater HT in the unignited state and the transition state for each plasma treatment.

The parameter calculation unit 102c uses the quantity of heat supplied by the quantity The unignited state measured by the measuring part 102b is fitted with the power supply in the transition state to calculate the heat and thermal resistance.

For example, the parameter calculation unit 102c obtains the heater power P _h0 in the non-ignited state for each elapsed time t for each heater HT. Furthermore, the parameter calculation unit 102c obtains the heater power Ph in the transition state for each elapsed time _t for each heater HT. Furthermore, the parameter calculation unit 102c divides each of the obtained heater power _{Ph and heater power P h0 by} the area of each heater HT to obtain each unit of the non-ignited state for each elapsed time t. The calorific value q _h0 from the heater HT per area, and the calorific value q _h per unit area from the heater HT in the transition state per elapsed time t.

Then, the parameter calculation unit 102c uses the above-mentioned formulas (1)-(11) as a calculation model, and calculates the calorific value q _h from the heater HT per unit area per elapsed time t for each heater HT. , and the fitting of the calorific value q _h0 from the heater HT per unit area to calculate the heat flux q _p and thermal resistance R _th ·A with the smallest error.

The parameter calculation unit 102c calculates the heat flux q _p and the thermal resistance R _th ·A by using the measured power supply in the unignited state and the transition state in a predetermined cycle. For example, the parameter calculation unit 102c calculates the heat flux _qp and Thermal resistance R _th ·A. In addition, for example, the parameter calculation unit 102c may calculate the heat flux q _p and the thermal resistance R _th ·A by using the power supplied in the unignited state and the transition state for each plasma treatment.

The set temperature calculation unit 102d calculates the set temperature of the heater HT to bring the wafer W to the target temperature by using the calculated heat input and thermal resistance for each heater HT. For example, the set temperature calculation unit 102d substitutes the calculated heat flux q _p and thermal resistance R _th ·A into formulas (5), (6) and (12) for each heater HT, and uses the formula ( 5) A ₁ , a ₂ , a ₃ , λ ₁ , λ ₂ , τ ₁ , τ ₂ shown in - (11) are calculated by formula (12) to make the temperature T _W of the wafer W the target temperature. The temperature T _h of the device HT. For example, the set temperature calculation unit 102d sets the elapsed time _t to a large predetermined value that can be regarded as a steady state, and calculates the temperature Th of the heater HT that makes the temperature TW of the wafer W the target temperature. The calculated temperature _Th of the heater HT is the temperature of the heater HT that makes the temperature of the wafer W the target temperature. In addition, the temperature _{Th h} of the heater HT that makes the temperature of the wafer W the target temperature can also be obtained from Equation (13).

In addition, the set temperature calculation unit 102d can also calculate the temperature T _W of the wafer W in the current temperature T _h of the heater HT according to the formula (12). For example, the set temperature calculation unit 102d calculates the temperature T _W of the wafer W when the elapsed time t is a large predetermined value that can be regarded as a steady state, using the current temperature _Th of the heater HT. Next, the set temperature calculation unit 102d calculates the difference ΔT _W between the calculated temperature T _W and the target temperature. Furthermore, the set temperature calculation unit 102d may calculate the temperature obtained by subtracting the difference _{ΔT W} from the current temperature Th of the heater HT as the temperature of the heater HT for making the temperature of the wafer W the target temperature.

The set temperature calculation unit 102d corrects the set temperature of each heater HT of the heater control unit 102a to the temperature of the heater HT that makes the temperature of the wafer W the target temperature.

The set temperature calculation unit 102d calculates the temperature of the heaters HT for bringing the temperature of the wafer W to the target temperature in a predetermined cycle, and corrects the set temperature of each heater HT. For example, the set temperature calculation unit 102d calculates the temperature of the heaters HT to make the temperature of the wafer W the target temperature every time the wafer W is exchanged, and corrects the set temperature of each heater HT. In addition, for example, the set temperature calculation unit 102d may calculate the temperature of the heater HT for making the temperature of the wafer W to the target temperature every time the plasma processing is performed, and correct the set temperature of each heater HT.

Thereby, the plasma processing apparatus 10 of this embodiment can control the temperature accuracy of the wafer W during plasma processing to a target temperature with good accuracy.

However, in the plasma processing apparatus 10, the characteristics in the processing container 12 may vary for each apparatus. Therefore, even if the plasma processing apparatus 10 uses the set temperature of each heater HT that makes the wafer W reach the target temperature in other plasma processing apparatuses 10, it may not be possible to control the temperature accuracy of the wafer W being plasma processed. is the target temperature.

Therefore, the plasma processing apparatus 10 of the present embodiment calculates the heat flux q _p and the thermal resistance R _th ·A according to the characteristics of the processing chamber 12 of the apparatus itself. Thereby, the plasma processing apparatus 10 of this embodiment can control the temperature accuracy of the wafer W during the plasma processing well, even when the characteristics in the processing chamber 12 vary from one apparatus to another. temperature.

In addition, in the plasma processing apparatus 10, the thermal characteristics of the mounting table 16 may change over time due to consumption of the electrostatic chuck 18 or the like.

Then, the plasma processing apparatus 10 of the present embodiment calculates the temperature of the heater HT for making the temperature of the wafer W to the target temperature in a predetermined cycle, and corrects the set temperature of each heater HT. Thus, the plasma processing apparatus 10 of the present embodiment can control the temperature of the wafer W during plasma processing to the target temperature with good accuracy even when the thermal characteristics of the mounting table 16 change with time.

In addition, the plasma processing apparatus 10 is in an abnormal state unsuitable for plasma processing due to a large consumption of the electrostatic chuck 18 or adhesion of deposits, etc., resulting in changes in the characteristics of the processing container 12 . In addition, there may be cases where abnormal wafers W are loaded into the plasma processing apparatus 10 .

Then, the warning unit 102e gives a warning based on a change in at least one of the heat input and the thermal resistance calculated by the parameter calculation unit 102c in a predetermined cycle. For example, at least one of the heat flux q _p and the thermal resistance R _th ·A is changed in the heat flux q _p and the thermal resistance R _th ·A calculated by the parameter calculation unit 102 c at a predetermined cycle for each heater HT. When it exceeds a predetermined allowable value, the warning unit 102e gives a warning. In addition, when at least one of the heat flux _qp and the thermal resistance R _th ·A calculated by the parameter calculation unit 102c deviates from a predetermined allowable range in a predetermined cycle, the warning unit 102e issues a warning. For the warning, any method may be used as long as the abnormality can be reported to the program manager or the manager of the plasma processing apparatus 10 . For example, the warning unit 102e displays a message reporting an abnormality on the user interface 103 .

Thereby, the plasma processing apparatus 10 of this embodiment can report the occurrence of an abnormality when the characteristics in the processing container 12 are in an abnormal state, or when an abnormal wafer W is loaded.

〔Flow of temperature control〕 Next, a temperature control method using the plasma processing apparatus 10 of this embodiment will be described. Fig. 8 is a flowchart showing an example of the flow of the temperature control method of the first embodiment. The temperature control method is performed at a predetermined timing, such as when plasma treatment is started.

The heater control part 102a controls the power supply to each heater HT so that each heater HT becomes a set temperature (step S10).

In the state where the heater control unit 102a controls the power supply to each heater HT so that the temperature of each heater HT becomes a fixed set temperature, the measurement unit 102b measures the electric power supplied to each heater in the non-ignited state and the transition state. Power supply to HT (step S11).

The parameter calculating section 102c uses, for each heater HT, the calculated pattern by dividing the measured supply power of the unignited state and the transition state by the area of the heater HT. The calorific value of the heater HT is fitted to calculate the calorific value and thermal resistance (step S12 ). For example, the parameter calculation part 102c uses the above-mentioned formulas (1)-(11) as a calculation mode, and calculates the calorific value q from the heater HT per unit area per elapsed time t for each heater HT. _h , and the fitting of heat generation q _h0 from the heater HT per unit area, the calculation error is the minimum heat flux q _p and thermal resistance R _th ·A.

The set temperature calculation unit 102d calculates the temperature of the heater HT to bring the wafer W to the target temperature using the calculated heat input and thermal resistance for each heater HT (step S13 ). For example, the set temperature calculation unit 102d substitutes the calculated heat flux q _p and thermal resistance R _th ·A into formulas (5), (6), and (12) for each heater HT, and uses formula (5 ) - a ₁ , a ₂ , a ₃ , λ ₁ , λ ₂ , τ ₁ , τ ₂ shown in (11), and calculated by formula (12) so that the temperature T _W of the wafer W becomes the heater of the target temperature The temperature T _h of HT. In addition, the temperature _{Th h} of the heater HT that makes the temperature of the wafer W the target temperature can also be obtained from Equation (13).

The set temperature calculation unit 102d corrects the set temperature of each heater HT of the heater control unit 102a to the temperature of the heater HT that makes the temperature of the wafer W the target temperature (step S14 ), and ends the process. That is, when the temperature of the heater HT that makes the temperature of the wafer W the target temperature deviates from the set temperature of each heater HT in the program (step S10 ) for controlling the power supply to each heater HT, the heater The control unit 102a re-controls the power supply to each heater HT to the temperature of the heater HT that makes the temperature of the wafer W the target temperature. Also, if there is no deviation, the set temperature is controlled as it is.

As mentioned above, the plasma processing apparatus 10 of this embodiment is provided with the mounting table 16, the heater control part 102a, the measurement part 102b, the parameter calculation part 102c, and the set temperature calculation part 102d. The mounting table 16 is provided with a heater HT capable of adjusting the temperature of the mounting surface on which the wafer W is mounted. The heater control unit 102a controls the electric power supplied to the heater HT to the set temperature set by the heater HT. The measurement unit 102b controls the power supplied to the heater HT by the heater control unit 102a so that the temperature of the heater HT becomes constant, and measures the unignited state of the unignited plasma and the power supplied to the heater HT after the plasma is ignited. The power supply in the transition state in which the power supply is reduced. The parameter calculation unit 102c uses the input power from the plasma and the thermal resistance between the wafer W and the heater HT as parameters and calculates the supply power in the transition state, using the value measured by the measurement unit 102b. The power supply in the unignited state and the transition state is fitted to calculate the heat and the aforementioned thermal resistance. The set temperature calculation unit 102d calculates the set temperature of the heater HT to bring the wafer W to a target temperature using the input heat and thermal resistance calculated by the parameter calculation unit 102c. Thereby, the plasma processing apparatus 10 can control the temperature accuracy of the wafer W during the plasma processing to the target temperature with good accuracy.

Moreover, in the plasma processing apparatus 10 of the present embodiment, the mounting table 16 is individually provided with a heater HT for each region that divides the mounting surface. The heater control unit 102a controls the power supply for each heater HT so that the heater HT installed for each area becomes the set temperature set for each area. The measurement unit 102b controls the power supply by the heater control unit 102a so that the temperature of each heater HT becomes constant, and measures the power supply in the non-ignited state and the transition state for each heater HT. The parameter calculation part 102c, according to each heater HT, uses the supply power of the unignited state and the transition state measured by the measurement part 102b to perform fitting for the calculation mode, and calculates the heat and thermal energy according to each heater HT resistance. The set temperature calculation unit 102d calculates the set temperature at which the wafer W becomes the target temperature for each heater HT using the heat input and thermal resistance calculated by the parameter calculation unit 102c. Thereby, even if the plasma processing apparatus 10 is provided with heaters HT for controlling the temperature of the wafer W individually in each area where the mounting surface is divided, the wafer W being plasma processed can be processed for each area. The temperature accuracy of the wafer W is well controlled to be the target temperature.

The process of correcting the set temperature of each heater HT to the temperature of the heater HT that makes the temperature of the wafer W the target temperature (step S14) may be followed by sending the ignited plasma to each heater HT in the ignited state. The procedure of supplying electric power to be measured (part of step S11) is directly carried out in the ignited state of the ignited plasma. In this way, each wafer W processed by the process is processed at a fixed temperature.

In addition, the calculated set temperature of the heater HT to bring the wafer W to the target temperature may be used in a program for controlling the power supply to each heater HT when the plasma treatment is completed and the wafer W is replaced ( The set temperature of each heater HT in step S10). That is, the process of correcting the set temperature of each heater HT to the temperature of the heater HT at which the temperature of the wafer W becomes the target temperature (step S14 ) is the same as the process for the next wafer W after replacement. The procedure (step S10 ) for controlling the power supply to each heater HT is the same. Thereby, the difference between the temperature of the heater HT for making the temperature of the wafer W at the target temperature and the set temperature of each heater HT in the process of controlling the power supply to each heater HT (step S10 ) can be minimized as much as possible. Deviate from.

In addition, in the plasma processing apparatus 10 of the present embodiment, the measuring unit 102b measures the power supplied in the unignited state and the transition state in a predetermined cycle. The parameter calculation unit 102c calculates the input heat and the thermal resistance by using the measured power supply in the unignited state and the transition state for each predetermined cycle. The warning unit 102e gives a warning based on a change in at least one of the heat input and the thermal resistance calculated by the parameter calculation unit 102c. Accordingly, the plasma processing apparatus 10 can report the occurrence of an abnormality when the characteristics in the processing container 12 are in an abnormal state or when an abnormal wafer W is loaded.

(Second Embodiment) Next, a second embodiment will be described. The configurations of the plasma processing apparatus 10 and the mounting table 16 of the second embodiment are the same as those of the plasma processing apparatus 10 and the mounting table 16 of the first embodiment shown in FIG. 1 and FIG.

Fig. 9 is a block diagram showing a schematic configuration of a control unit for controlling the plasma processing apparatus according to the second embodiment. The configuration of the control unit 100 of the second embodiment is the same as that of the control unit 100 of the first embodiment shown in FIG. 3 , so the same symbols are assigned to the same parts, and the main differences will be described.

However, when the power supply to each heater HT is controlled by the heater control unit 102a so that the temperature of each heater HT becomes constant and the power supply in the unlit state and the transition state is measured, the temperature of the wafer W In terms of T _W , the transition state increases the temperature more due to the incoming heat from the plasma than the unignited state. Fig. 10 schematically shows the variation of the temperature of the wafer. For example, the heater control unit _102a controls the temperature Th of the heater HT to a predetermined set temperature Tb so that the temperature T _W of the wafer W becomes a predetermined target temperature Ta in an unignited state. When the plasma is ignited in this state, the temperature of the wafer W rises to the temperature Ta′ by the heat input from the plasma. As in the case of raising the temperature of the wafer W to the temperature Ta′, the heater control unit _102a lowers the temperature Th of the heater HT to the temperature Tb′ so that the temperature of the wafer W becomes the target temperature Ta. As described above, when the temperature of the wafer W is raised to the temperature Ta′ and then controlled to the target temperature Ta, it takes time for the plasma processing apparatus 10 to bring the temperature T _W of the wafer W to the target temperature Ta.

Then, the control unit 100 of the second embodiment memorizes the initial values of the heat flux q _p and the thermal resistance R _th ·A in the memory unit 104 as the setting information 104 a. For example, the program manager or manager inputs the initial values of the heat flux q _p and the thermal resistance R _th ·A obtained through past experiences or experiments through the user interface 103 . The control unit 100 memorizes the initial values of the heat flux q _p and the thermal resistance R _th ·A input from the user interface 103 in the memory unit 104 as setting information 104 a.

The set temperature calculation unit 102d reads out the initial values of the heat flux q _p and the thermal resistance R _th ·A from the setting information 104a when starting the plasma treatment. The set temperature calculation unit 102d calculates the set temperature of each heater HT to bring the wafer to the target temperature using the formula (12) or formula (13) from the read heat flux q _p and thermal resistance R _th・A . The heater control part 102a controls the electric power supply control to each heater HT so that each heater HT may become set temperature calculated by the set temperature calculation part 102d. The memory unit 104 memorizes the appropriate initial values of the heat flux _qp and the thermal resistance R _th ·A as the setting information 104a, so that the set temperature calculation unit 102d can be used even for the first wafer W, even if there is an input from the plasma. Heat can also calculate the set temperature of the heater HT so that the temperature of the wafer W becomes the target temperature. For example, in the case of FIG. 10 , the set temperature calculation unit 102d can calculate the temperature Tb′ of the heater HT so that the temperature of the wafer W also becomes the target temperature Ta for the first wafer W. Thereby, the plasma processing apparatus 10 can shorten the time until the temperature T _W of the first wafer W reaches the target temperature Ta.

When the power supply to each heater HT is controlled by the parameter calculation unit 102c so that each heater HT reaches a set temperature, the measurement unit 102b measures the supply to each heater HT in the non-ignited state and the transition state. electricity.

For each heater HT, the parameter calculation unit 102c uses the calculation model for calculating the supply power in the transition state with the heat input from the plasma and the thermal resistance between the wafer W and the heater HT as parameters, using The unignited state measured by the measurement unit 102b is fitted with the power supply in the transition state to calculate the actual heat input and thermal resistance in the plasma treatment.

For example, the parameter calculation unit 102c obtains the heater power P _h0 in the non-ignited state for each elapsed time t for each heater HT. Furthermore, the parameter calculation unit 102c obtains the heater power P _h in the transition state for each elapsed time t for each heater HT. Furthermore, the parameter calculation unit 102c divides each of the obtained heater power _{Ph and the heater power Ph0 by} the area of each heater HT to obtain each of the non-ignited states for each elapsed time t. The calorific value q _h0 per unit area from the heater HT, and the calorific value q _h per unit area of the transition state per elapsed time t from the heater HT.

Then, the parameter calculation unit 102c uses the above-mentioned formulas (1)-(11) as a calculation model, and calculates, for each heater HT, the calorific value q _h from the heater HT per unit area per elapsed time t, And the fitting of the calorific value q _h0 from the heater HT per unit area to calculate the heat flux q _p and thermal resistance R _th ·A with the smallest error in the actual plasma treatment.

The set temperature calculation unit 102d calculates the temperature at which the wafer W reaches the target temperature using the actual plasma processing heat flux _qp and thermal resistance R _th ·A calculated by the parameter calculation unit 102c for each heater HT. The set temperature of the heater HT.

The set temperature calculation unit 102d judges that the set temperature of each heater HT calculated from the actual heat flux q _p and thermal resistance R _th ·A of the plasma treatment is higher than the set temperature of each heater HT calculated from the heat flux q _p and thermal resistance R _th ·A Whether the set temperature of each heater HT calculated from the initial value of A deviates from the predetermined value or more. When the set temperature calculation unit 102d judges that it deviates from the predetermined value or more, the set temperature of the heater control unit 102a is updated to each heater calculated from the actual heat flux q _p and thermal resistance R _th ·A of the plasma treatment. HT's set temperature. In this way, the set temperature of each heater HT is updated to the set temperature calculated from the actual heat flux q _p and thermal resistance R _th・A of the plasma treatment, so the temperature accuracy of the wafer W can be well controlled as the target temperature. The heater control part 102a controls the electric power supplied to each heater HT so that it may become the updated set temperature.

The set temperature calculation unit 102d stores the actual heat flux q _p and thermal resistance R _th ·A of the plasma treatment in the setting information 104a when the temperature deviates from the predetermined value or more. For example, the set temperature calculation unit 102d replaces the initial values of the heat flux _qp and thermal resistance _Rth ·A stored in the setting information 104a with the actual heat flux _qp and thermal resistance _Rth ·A of the plasma treatment. In this way, the actual heat flux q _p and thermal resistance R _th · A of the plasma treatment are stored in the setting information 104 a as initial values and used. That is, the set temperature calculation unit 102d always updates the heat flux q _p and thermal resistance R _th ·A previously stored in the memory unit 104 to the latest values when the set temperature deviates from the predetermined value or more.

〔Flow of temperature control〕 Next, a temperature control method using the plasma processing apparatus 10 of the second embodiment will be described. Fig. 11 is a flowchart showing an example of the flow of the temperature control method of the second embodiment.

The set temperature calculating unit 102d reads out the initial values of the heat flux q _p and the thermal resistance R _th ·A from the setting information 104a when starting the plasma treatment (step S20).

The set temperature calculation unit 102d calculates the set temperature of each heater HT to be the target temperature of the wafer W from the heat flux _qp and the thermal resistance R _th ·A using the formula (12) or the formula (13) (step S21).

The heater control part 102a controls the electric power supplied to each heater HT so that each heater HT may become set temperature (step S22).

The measuring unit 102b measures the difference between the non-ignited state and the transition state when the power supplied to each heater HT is controlled by the heater control unit 102a so that the temperature of each heater HT becomes a fixed set temperature. Power supply to each heater HT (step S23).

The parameter calculation unit 102c uses the heat source per unit area obtained by dividing the measured power supply in the unignited state and transition state by the area of the heater HT for the calculation mode for each heater HT. The heating value of the device is fitted to calculate the input heat and thermal resistance (step S24). For example, the parameter calculation unit 102c uses the above formulas (1)-(11) as a calculation model, and calculates the calorific value q _h from the heater HT per unit area per elapsed time t for each heater HT. , and the fitting of the calorific value q _h0 from the heater HT per unit area, and calculate the heat flux q _p and thermal resistance R _th ·A that minimize the error system.

The set temperature calculation unit 102d calculates the temperature of the heater HT to bring the wafer W to the target temperature using the calculated heat input and thermal resistance for each heater HT (step S25 ). For example, the set temperature calculation unit 102d substitutes the calculated heat flux q _p and thermal resistance R _th ·A into formulas (5), (6) and (12) for each heater HT, and uses the formula ( 5) A ₁ , a ₂ , a ₃ , λ ₁ , λ ₂ , τ ₁ , τ ₂ shown in - (11) are calculated by formula (12) to make the temperature T _W of the wafer W the target temperature. The temperature T _h of the device HT. In addition, the temperature _{Th h} of the heater HT that makes the temperature of the wafer W the target temperature can also be obtained from Equation (13).

The set temperature calculation unit 102d judges whether the set temperature of each heater HT calculated from the actual heat flux q _p and thermal resistance R _th ·A of the plasma treatment is consistent with the heat flux q _p and thermal resistance R _th ·A The set temperature of each heater HT calculated from the initial value deviates from the predetermined value or more (step S26).

If the deviation exceeds the predetermined value (step S26: Yes), the set temperature calculation unit 102d updates the set temperature of the heater control unit 102a to be calculated from the actual heat flux q _p and thermal resistance R _th ·A of the plasma treatment The set temperature of each heater HT (step S27).

The set temperature calculation unit 102d replaces the initial values of the heat flux _qp and thermal resistance _Rth ·A stored in the setting information 104a with the actual heat flux _qp and thermal resistance _Rth ·A of the plasma treatment (step S28 ). In this way, the actual heat flux q _p and thermal resistance R _th · A of the plasma treatment are stored in the setting information 104 a as initial values and used.

On the other hand, when it is not deviated from the predetermined value or more (step S26: No), the set temperature calculation unit 102d does not update the set temperature, and controls as it is (step S29).

The set temperature calculation unit 102d determines whether or not the next plasma treatment will be performed next (step S30). In the case where the next plasma treatment is to be performed successively (step S30: Yes), transfer to the above-mentioned step S22. On the other hand, when the next plasma treatment is not performed (step S30: No), the process ends.

As described above, the plasma processing apparatus 10 of the present embodiment memorizes the heat input amount and thermal resistance in the memory unit 104 as the setting information 104a. The set temperature calculation unit 102d calculates the set temperature of the heater HT to bring the wafer W to the target temperature using the input heat amount and thermal resistance stored in the storage unit 104 . Thereby, the plasma processing apparatus 10 can shorten the time until the temperature T _W of the wafer W reaches the target temperature Ta. In addition, since the plasma processing apparatus 10 sets the temperature of the heater HT to be the target temperature of the wafer W predicted in advance, the error in the temperature of the wafer W after the plasma ignition is reduced, and the temperature of the wafer W during the plasma processing can be reduced. The temperature of the wafer W is more precisely controlled to a target temperature.

The set temperature calculation unit 102d judges whether the calculated set temperature deviates more than a predetermined value from the set temperature calculated using the heat input and thermal resistance calculated by the parameter calculation unit 102c. The set temperature calculation unit 102d updates the input heat and thermal resistance stored in the memory unit 104 to the input heat and thermal resistance calculated by the parameter calculation unit 102c when the set temperature deviates from the predetermined value or more. Thereby, the temperature of the wafer W can be controlled to the target temperature with higher precision in the plasma treatment performed next.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range described in the said embodiment. It is clear to those skilled in the art to which this invention belongs that various changes and improvements can be added to the said embodiment. In addition, it is clear from the description of the scope of application that such modifications or improvements are also included in the technical scope of the present invention.

For example, in the above-mentioned embodiment, the case where plasma processing is performed on a semiconductor wafer as an object to be processed has been described as an example, but the present invention is not limited thereto. The object to be treated can be any object as long as the temperature affects the progress of the plasma treatment.

In addition, in the above-mentioned second embodiment, the case where the setting information 104a stores one initial value of the heat flux q _p and the thermal resistance R _th ·A is described as an example, but it is not limited thereto. From the point of view that the heat flux q _p and thermal resistance R _th ·A depend on the conditions of plasma treatment, when different plasma treatment conditions are used, the predicted heat flux q and thermal resistance R _th must also be replaced・A. Therefore, the memory unit 104 correlates the heat flux q _p and the thermal resistance R _th ·A with the dependent plasma processing parameters and stores them. For example, the parameters of the plasma treatment that have dependence on the thermal resistance R _th include the pressure of the heat transfer gas, the voltage applied to the electrostatic chuck 18 , the temperature of the refrigerant, and the surface state of the electrostatic chuck 18 . Parameters of plasma processing having a dependence on the heat flux q _p include radio frequency power HFS, radio frequency power LFS, pressure in the processing container 12, gas species, and the like. The set temperature calculation unit 102d can also read out the heat flux q _p and the thermal resistance R _th ·A corresponding to the plasma treatment conditions of the plasma treatment performed from the memory unit 104 .

In addition, in the above-mentioned embodiments, the case where plasma etching is performed as an example of plasma treatment has been described, but it is not limited thereto. Plasma treatment can be done as long as plasma is used and the treatment is affected by temperature.

10‧‧‧Plasma treatment device 12‧‧‧Disposal container 12a‧‧‧Earth conductor 12e‧‧‧Exhaust port 12g‧‧‧Import and export 14‧‧‧Support Department 16‧‧‧Placing table 18‧‧‧Electrostatic Chuck 18a‧‧‧Location area 18b‧‧‧peripheral area 18m‧‧‧Body 19‧‧‧Adhesive layer 20‧‧‧abutment 22‧‧‧DC power supply 24‧‧‧Refrigerant channel 26a, 26b‧‧‧Piping 30‧‧‧Upper electrode 32‧‧‧Insulating shielding components 34‧‧‧electrode plate 34a‧‧‧Gas injection hole 36‧‧‧electrode support 36a‧‧‧Gas diffusion chamber 36b‧‧‧gas flow hole 36c‧‧‧Gas inlet 38‧‧‧gas supply pipe 40‧‧‧gas source group 42‧‧‧valve group 44‧‧‧Flow controller group 46‧‧‧Sediment barrier 48‧‧‧Exhaust plate 50‧‧‧exhaust device 52‧‧‧Exhaust pipe 54‧‧‧gate valve 100‧‧‧Control Department 101‧‧‧External interface 102‧‧‧Process Controller 102a‧‧‧Heater control unit 102b‧‧‧Measurement Department 102c‧‧‧Parameter calculation department 102d‧‧‧Set temperature calculation department 102e‧‧‧Warning Department 103‧‧‧User Interface 104‧‧‧memory E1‧‧‧electrode ESC‧‧‧Electrostatic Chuck FR‧‧‧focus ring HFS‧‧‧First RF Power Supply HP‧‧‧Heater power supply HT‧‧‧heater LFS‧‧‧Second RF power supply MU1, MU2‧‧‧Matching PD‧‧‧Power Detection Department S‧‧‧Processing Space SW1‧‧‧switch Ta‧‧‧target temperature Ta´‧‧‧temperature Tb‧‧‧set temperature Tb´‧‧‧temperature TD‧‧‧Temperature Measuring Device W‧‧‧Wafer

Fig. 1 schematically shows a plasma treatment apparatus according to a first embodiment. Fig. 2 is a plan view showing the mounting table of the first embodiment. Fig. 3 is a block diagram showing a schematic configuration of a control unit for controlling the plasma processing apparatus according to the first embodiment. Figure 4 schematically shows the flow of energy affecting the temperature of the wafer. Figure 5A schematically shows the flow of energy in the unignited state. Figure 5B schematically shows the flow of energy in the ignited state. 6(A) to (B) are examples of changes in the temperature of the wafer W and the power supplied to the heater HT. Figure 7 schematically shows the flow of energy in the ignited state. Fig. 8 is a flowchart showing an example of the flow of the temperature control method of the first embodiment. Fig. 9 is a block diagram showing a schematic configuration of a control unit for controlling the plasma processing apparatus according to the second embodiment. Fig. 10 schematically shows the variation of the temperature of the wafer. Fig. 11 is a flowchart showing an example of the flow of the temperature control method of the second embodiment.

100‧‧‧Control Department

101‧‧‧External interface

102‧‧‧Process Controller

102a‧‧‧Heater control unit

102b‧‧‧Measurement Department

102c‧‧‧Parameter calculation department

102d‧‧‧Set temperature calculation department

102e‧‧‧Warning Department

103‧‧‧User Interface

104‧‧‧memory

HP‧‧‧Heater power supply

PD‧‧‧Power Detection Department

TD‧‧‧Temperature Measuring Device

Claims (6)

A plasma processing device comprising: a mounting table provided with a heater capable of adjusting the temperature of a mounting surface on which an object to be processed as a plasma processing object is mounted; a heater control unit controlling Supply power to the heater so that the heater becomes the set temperature; the measurement unit controls the power supply to the heater by the heater control unit so that the temperature of the heater becomes constant, and measures The unignited state of the unignited plasma and the power supply in the transitional state in which the power supply to the heater is reduced after the plasma is ignited; the parameter calculation unit uses the heat input from the plasma and the distance between the object to be processed and the heater The thermal resistance is used as a parameter to calculate the calculation model of the power supply in the transition state, and the power supply in the unignited state and the transition state measured by the measurement unit is used to perform fitting to calculate the heat input and the thermal resistance and a set temperature calculation unit that calculates a set temperature of the heater to bring the object to be processed to a target temperature using the input heat and the thermal resistance calculated by the parameter calculation unit. As for the plasma processing device in claim 1 of the scope of the patent application, wherein, in the mounting table, the heater is individually provided in each area formed by dividing the mounting surface, and the heater control part controls each The heaters installed in each area control their power supply so that the heaters installed in each area become the set temperature set for each area. The measurement part controls the power supply through the heater control part so that each heating The temperature of the heater becomes fixed, and the power supply of the non-ignited state and the transition state is measured for each heater, The parameter calculation unit, for each of the heaters, uses the power supply in the unignited state and the transition state measured by the measurement unit to perform fitting for the calculation model, so as to calculate the input power for each of the heaters. The amount of heat and the thermal resistance, the set temperature calculation unit calculates the set temperature for making the object to be processed a target temperature for each of the heaters using the input heat amount and the thermal resistance calculated by the parameter calculation unit. The plasma processing device as claimed in claim 1 or 2 of the scope of the patent application, wherein the measurement unit measures the power supply of the unignited state and the transition state in a predetermined cycle, and the parameter calculation unit measures in each predetermined cycle , using the measured supply power in the unignited state and the transition state to calculate the heat input and the thermal resistance respectively, and further comprising: a warning unit based on the heat input and the heat input calculated by the parameter calculation unit A change in at least one of the resistances, and a warning is issued. Such as the plasma processing device of claim 1 or 2 of the scope of the patent application, wherein, it is further equipped with: a memory unit that memorizes the input heat and the thermal resistance; the set temperature calculation unit uses the input heat and the heat stored in the memory unit The thermal resistance is used to calculate the set temperature of the heater that makes the object to be processed a target temperature, and the set temperature is compared with the set temperature calculated by using the heat input and the thermal resistance calculated by the parameter calculation part. If it deviates from the predetermined amount or more, the input heat and the thermal resistance memorized by the memory unit are updated to the input heat and the thermal resistance calculated by the parameter calculation unit. A temperature control method characterized by performing the following processes: The electric power supplied to the heater on the mounting table provided with the heater capable of adjusting the temperature of the mounting surface on which the object to be processed as the plasma treatment object is mounted is controlled so that the heater's The temperature becomes fixed, and the power supply in the unignited state of the unignited plasma and the transition state in which the power supply to the heater is reduced after the plasma is ignited are measured; The calculation model that uses the thermal resistance between the heaters as a parameter and calculates the power supply in the transition state, and uses the measured power supply in the unignited state and the transition state to perform fitting to calculate the heat input and the thermal resistance and using the calculated input heat and the thermal resistance to calculate the set temperature of the heater for making the object to be processed a target temperature. A temperature control program characterized by executing the following process: the heater on the mounting table provided with the heater capable of adjusting the temperature of the mounting surface on which the object to be processed as the object of plasma treatment is mounted Control the supply power of the heater so that the temperature of the heater becomes constant, and measure the supply power in the unignited state of the unignited plasma and the transition state in which the power supply to the heater is reduced after the plasma is ignited; The calculation model that calculates the power supply in the transition state by using the heat input from the plasma and the thermal resistance between the object to be processed and the heater as parameters, using the measured power supply in the unignited state and the transition state fitting to calculate the input heat and the thermal resistance; and using the calculated input heat and the thermal resistance to calculate the set temperature of the heater to make the object to be processed a target temperature.

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