Plasma treatment device, control method, and control program

Abstract

Provided are a plasma treatment device, a control method, and a control program.　A plasma treatment device for performing a plasma treatment on a substrate placed on a placing table comprises: an annular member arranged around a substrate; an adjustment unit for adjusting sheath thickness above the annular member; a measurement unit for measuring the potential of the annular member; and a control unit for controlling values of a plurality of types of control parameters in the plasma treatment. The control unit acquires data indicating a potential variation amount in a case where the amount of adjustment by the adjustment unit is modified and data indicating a potential variation amount in a case where, for each control parameter, the control parameter value is changed. The control unit determines, on the basis of the acquired data, the type of a control parameter which is to be changed at the same time the adjustment amount is modified, and calculates the control parameter value so as to suppress the potential variation amount accompanying the adjustment amount modification.

Description

Plasma processing apparatus, control method, and control program

[0001] The present disclosure relates to a plasma processing apparatus, a control method, and a control program.

[0002] A plasma processing apparatus is used for plasma processing of a substrate. In a chamber of the plasma processing apparatus, the substrate is placed in a region surrounded by an annular member called an edge ring or a focus ring.

[0003] When plasma processing is performed using a plasma processing apparatus, the annular member is worn away and its thickness decreases. As the thickness of the annular member decreases, the upper end position of the sheath above the annular member becomes lower. When the upper end position of the sheath above the annular member becomes lower, ions from the plasma collide with the edge of the substrate at an oblique angle. As a result, a recess formed at the edge of the substrate becomes inclined. Patent Document 1 discloses a configuration in which a DC voltage is applied to the annular member to suppress the inclination of the recess formed at the edge of the substrate.

[0004] Japanese Patent Application Laid-Open No. 2007-258417

[0005] The present disclosure provides a plasma processing apparatus, a control method, and a control program that suppress deterioration of process characteristics due to wear of an annular member disposed within the apparatus.

[0006] A plasma processing apparatus according to one embodiment of the present disclosure is a plasma processing apparatus that performs plasma processing on a substrate placed on a mounting table, and includes an annular member arranged around the substrate, an adjustment unit that adjusts the sheath thickness on the annular member, a measurement unit that measures the potential of the annular member, and a control unit that controls the values ​​of multiple control parameters in the plasma processing.The control unit acquires data indicating the amount of change in the potential when the adjustment amount in the adjustment unit is changed, and data indicating the amount of change in the potential when the value of the control parameter is changed for each control parameter, and based on the acquired data, determines the type of control parameter that should be changed simultaneously with the change in the adjustment amount, and calculates the value of the control parameter so as to suppress the amount of change in the potential that accompanies the change in the adjustment amount.

[0007] According to the present disclosure, it is possible to suppress the deterioration of process characteristics due to wear of an annular member disposed in an apparatus.

[0008] FIG. 1 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus. FIG. 2 is a diagram for explaining fluctuations in tilting due to wear of an edge ring. FIG. 3 is a diagram for explaining fluctuations in tilting due to wear of an edge ring. FIG. 4 is an explanatory diagram for explaining an effect when FRDC_% is changed. FIG. 5 is an explanatory diagram for explaining a control method for RF_pw in an embodiment. FIG. 6 is an explanatory diagram for explaining a method for calculating an amount of change in RF_pw. FIG. 7 is a flowchart for explaining the procedure of processing executed by a control unit. FIG. 8 is a graph showing simulation results at a specific step. FIG. 9 is a graph showing simulation results at another step.

[0009] An example of the configuration of a plasma processing system will be described below: Fig. 1 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus.

[0010] The plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a controller 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0011] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0012] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF (Radio Frequency) power supply 31 and / or a DC (Direct Current) power supply 32 (described later) may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal (described later) is supplied to the at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple lower electrodes. Furthermore, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0013] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material. The edge rings are also referred to as focus rings (FR). The ring assembly 112 illustrated in FIG. 1 includes an annular edge ring 112a and an annular cover ring 112b disposed around the edge ring 112a.

[0014] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the backside of the substrate W and the central region 111a.

[0015] The showerhead 13 is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The process gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0016] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include one or more flow modulation devices to modulate or pulse the flow rate of the at least one process gas.

[0017] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates a plasma from at least one process gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more process gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0018] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode. Hereinafter, the source RF power (source power) will also be referred to as HF_pw.

[0019] The second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed. Hereinafter, the bias RF power (bias power) will also be referred to as LF_pw. In addition, when there is no need to distinguish between the source RF power and the bias RF power, they will also be referred to as RF_pw.

[0020] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the at least one lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to the at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0021] In various embodiments, at least one of the first and second DC signals may be pulsed. In this case, a sequence of pulsed voltages is applied to at least one lower electrode and / or at least one upper electrode. The pulsed voltage may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generator for generating a sequence of pulsed voltages from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a pulsed voltage generator. When the second DC generator 32b and the waveform generator constitute a pulsed voltage generator, the pulsed voltage generator is connected to at least one upper electrode. The pulsed voltage may have a positive polarity or a negative polarity. Furthermore, the sequence of pulsed voltages may include one or more positive pulsed voltages and one or more negative pulsed voltages within one cycle. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0022] The plasma processing system includes a variable DC power supply 33 coupled to the edge ring 112a and an electrometer 34 that measures the potential of the edge ring 112a. In one embodiment, the variable DC power supply 33 is connected to the edge ring 112a and configured to generate a third DC signal. The generated DC signal is applied to the edge ring 112a. Hereinafter, the voltage of the third DC signal applied to the edge ring 112a will be referred to as FRDC, and the adjustment amount of the third DC signal will be referred to as FRDC_%. The electrometer 34 is a contact or non-contact type electrometer and measures the potential of the edge ring 112a. Data on the potential measured by the electrometer 34 is output to the controller 2.

[0023] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0024] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. The program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media M readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0025] Next, a change in the sheath caused by wear of the edge ring 112a and the occurrence of tilting will be described. Figures 2A and 2B are diagrams for explaining the change in tilting caused by wear of the edge ring 112a.

[0026] 2A shows a state in which the edge ring 112a is not worn. The edge ring 112a is disposed in the annular region 111b of the substrate support 11 as part of the ring assembly 112. The thickness of the edge ring 112a is designed so that the height of the upper surface of the edge ring 112a and the height of the upper surface of the wafer W are the same when the edge ring 112a is disposed in the annular region 111b. When the edge ring 112a is not worn, the sheath on the wafer W and the sheath on the edge ring 112a generated during plasma processing have the same thickness, and no step is generated.

[0027] At this time, the ion irradiation angle with respect to the wafer W and the edge ring 112a is approximately perpendicular to these surfaces, and as a result, the shape of the recesses (etched shape) formed in the wafer W is approximately perpendicular in both the central region and the peripheral region of the wafer W, and tilting, in which the shape of the recesses is tilted, does not occur.

[0028] During plasma processing, the edge ring 112a is exposed to plasma and gradually wears away. FIG. 2B shows the worn state of the edge ring 112a. As the thickness of the edge ring 112a decreases due to wear, the upper surface of the edge ring 112a becomes lower than the upper surface of the wafer W. As a result, a step occurs between the sheath above the edge ring 112a and the sheath above the wafer W, as shown in FIG. 2B.

[0029] As a result of the step occurring in the sheath, the direction of ion irradiation becomes oblique in the peripheral region of the wafer W, as shown by the arrow in the figure, and tilting occurs, in which the shape of the recess formed in the wafer W becomes oblique.

[0030] One known method for eliminating such tilting due to wear of the edge ring 112a is to change the FRDC_% according to the RF application time and adjust the thickness of the sheath formed above the edge ring 112a.

[0031] FIG. 3 is an explanatory diagram illustrating the effect of changing FRDC_%. The top graph in FIG. 3 shows the change in FRDC_% over time. The horizontal axis of the graph represents RF application time, and the vertical axis represents FRDC_%. Here, RF application time represents the time during which RF_pw is supplied from the RF power supply 31 to the plasma generation source and the lower electrode. FRDC_% represents a ratio index indicating how much more FRDC is applied relative to the self-bias (Voff). The top graph in FIG. 3 shows an example in which FRDC_% is increased by a required amount when the RF application time reaches T4 and T7. By changing the voltage (FRDC) applied to the edge ring 112a from the variable DC power supply 33 in accordance with FRDC_%, the thickness of the sheath formed above the edge ring 112a can be adjusted. In this embodiment, a configuration will be described in which the amount of FRDC applied is adjusted using a ratio index (FRDC_%), but a configuration in which the amount of FRDC applied is adjusted using a voltage value difference (FRDC_V) instead of a ratio index may also be used.

[0032] The second graph from the top in Fig. 3 shows the change in RF_pw over time. The horizontal axis of the graph represents RF application time, and the vertical axis represents RF_pw. RF_pw represents the source RF power supplied to the plasma generation source (or the bias RF power supplied to the lower electrode). The second graph from the top in Fig. 3 shows an example in which RF_pw was not changed.

[0033] The third graph from the top in Figure 3 shows the change in Voff over time. The horizontal axis of the graph represents RF application time, and the vertical axis represents Voff. Voff represents the potential of the edge ring 112a, and is a value measured by the electrometer 34. The third graph from the top in Figure 3 shows that when FRDC_% is increased without changing the value of RF_pw, the potential of the edge ring 112a increases in accordance with the increase in FRDC_%.

[0034] The graph at the bottom of Figure 3 shows the change in C_ER over time. The horizontal axis of the graph represents RF application time, and the vertical axis represents C_ER. C_ER represents the etching rate at the center of the substrate. The etching rate is a value measured, for example, by a measuring instrument that optically measures the pattern shape on the substrate surface. The graph at the bottom of Figure 3 shows that when FRDC_% is increased without changing the value of RF_pw, the etching rate at the center of the substrate increases as FRDC_% increases.

[0035] 3, it can be seen that when FRDC_% is increased according to the RF application time without changing the value of RF_pw in order to eliminate tilting due to wear of the edge ring 112a, the etching rate at the center of the substrate increases. Furthermore, it can be seen from the experimental results in FIG. 3 that there is a correlation between the etching rate at the center of the substrate and the potential of the edge ring 112a.

[0036] Therefore, the inventors of the present application focus on the potential of the edge ring 112a, which is correlated with the etching rate at the center of the substrate, and propose a method of suppressing an increase in the etching rate at the center of the substrate by calculating RF_pw and controlling RF_pw so that the potential of the edge ring 112a does not fluctuate when FRDC_% is changed.

[0037] FIG. 4 is an explanatory diagram illustrating a control method for RF_pw in an embodiment. The graph shown at the top of FIG. 4 shows the change in FRDC_% over time. The horizontal axis of the graph represents RF application time, and the vertical axis represents FRDC_%. The graph at the top of FIG. 4 shows an example in which FRDC_% is increased by a required increase amount when the RF application time reaches T4 and T7, respectively.

[0038] The second graph from the top in Fig. 4 shows the change in RF_pw over time. The horizontal axis of the graph represents RF application time, and the vertical axis represents RF_pw. The second graph from the top in Fig. 4 shows an example in which RF_pw is decreased at the same timing (T4, T7) as when FRDC_% is increased.

[0039] The third graph from the top in Figure 4 shows the change in Voff over time. The horizontal axis of the graph represents RF application time, and the vertical axis represents Voff. If the value of RF_pw is calculated and controlled so that Voff does not fluctuate, the change in Voff over time can be suppressed, as shown in the third graph from the top in Figure 4.

[0040] The graph at the bottom of Fig. 4 shows the change in C_ER over time. The horizontal axis of the graph is RF application time, and the vertical axis is C_ER. When the value of RF_pw is calculated and controlled so that Voff does not fluctuate, the time fluctuation of the etching rate (C_ER) at the center of the substrate, which is correlated with Voff, is also suppressed, as shown in the graph at the bottom of Fig. 4.

[0041] A method for calculating the RF_pw change amount will be described below. FIG. 5 is an explanatory diagram illustrating the method for calculating the RF_pw change amount. The control unit 2 of the plasma processing system executes a check recipe using a dummy substrate after completing parts maintenance such as replacement of consumables, dry cleaning of the processing chamber, and seasoning to bring the processing chamber closer to a stable mass production state. The check recipe includes steps of gradually varying RF_pw and measuring Voff (the potential of the edge ring 112a) at that time. The control unit 2 calculates the RF_pw change amount using data obtained during execution of the check recipe. The data used for the calculation is preferably collected for each step type, such as a step for cutting an organic film or a step for cutting a silicon film.

[0042] To address tilting due to wear of the edge ring 112a, the controller 2 increases FRDC_% by a required increment at set time intervals. For example, the increment of FRDC_% can be determined according to the RF application time, such as increasing FRDC_% by 10% every 50 hours until the RF application time reaches 200 hours, and then increasing FRDC_% by 15% every 50 hours after 200 hours have elapsed. The timing for increasing FRDC_% and the increment when correcting FRDC_% are not limited to those described above and can be designed in advance according to the degree of tilting formed on the substrate W.

[0043] When executing the check recipe, the control unit 2 increases FRDC_% according to the RF application time and collects Voff data when RF_pw is varied in a stepwise manner. The example of Fig. 5 shows an example in which, for a specific step (e.g., a step of cutting an organic film), FRDC_% is increased according to the RF application time, and Voff data is collected when HF_pw is varied in a stepwise manner, and Voff data is collected when LF_pw is varied in a stepwise manner.

[0044] Based on the collected data, the control unit 2 calculates the amount of change in RF_pw that will suppress fluctuations in Voff. Specifically, based on the correlation between FRDC_%, RF_pw, and Voff, the control unit 2 can determine the control parameter (HF_pw or LF_pw in this example) that should be changed simultaneously with the change in FRDC_% and its value.

[0045] For example, as shown in the graph of FIG. 5 , data obtained during execution of the check recipe may show that Voff increases with an increase in FRDC_% and that Voff increases with an increase in HF_pw. In this case, decreasing HF_pw when FRDC_% is increased can suppress the increase in Voff. On the other hand, suppose results are obtained that Voff increases with an increase in FRDC_% and that Voff does not change with an increase in LF_pw. In this case, increasing or decreasing LF_pw when FRDC_% is increased cannot suppress the increase in Voff. Therefore, in the example shown in FIG. 5 , the control unit 2 selects "HF_pw" as the control parameter to be changed simultaneously with the change in FRDC_%.

[0046] FIG. 5 shows an example in which HF_pw is selected as the control parameter to be changed simultaneously with the change in FRDC_%, but depending on the type of step, LF_pw may be selected, or both HF_pw and LF_pw may be selected.

[0047] The control unit 2 calculates the value of a control parameter (HF_pw in the example of FIG. 5 ) that should be changed simultaneously with the change in FRDC_% for the selected control parameter. Specifically, the control unit 2 obtains, from data obtained during execution of the check recipe, an adjustment amount a of FRDC_% corresponding to the RF application time, a rate (slope) b of Voff increasing relative to FRDC_%, and a rate (slope) c of Voff increasing relative to HF_pw, and derives a calculation formula for calculating the value of the changed control parameter (HF_pw in the example of FIG. 5 ) using the adjustment amount a of FRDC_% as an input. The above calculation formula can be derived using a regression method. The control unit 2 calculates the value of the control parameter using the derived calculation formula. The control unit 2 may calculate the value of the control parameter (the value after change) or the amount of change in the control parameter.

[0048] Instead of calculating the value of the control parameter using a formula, the value of the control parameter may be derived using a learning model such as machine learning. The learning model uses data obtained when the check recipe is executed as training data and learns to output the value of the control parameter when an adjustment amount a of FRDC_% is input.

[0049] 6 is a flowchart illustrating the procedure of the process executed by the control unit 2. After completing processes such as part maintenance, dry cleaning, and seasoning, the control unit 2 executes the following process in accordance with a check recipe using a dummy substrate.

[0050] During execution of the check recipe using the dummy substrate, the control unit 2 gradually changes the values ​​of the FRDC_% and the control parameters, and acquires data on the potential of the edge ring 112a measured by the electrometer 34 (step S101). The acquired potential data is stored in the memory unit 2a2 together with the values ​​of the FRDC_% and the control parameters. The values ​​of the FRDC_% and the control parameters stored in the memory unit 2a2 may be set values ​​or actual measured values.

[0051] Based on the acquired data, the control unit 2 determines the control parameters to be changed simultaneously with the change in FRDC_% (step S102). In this embodiment, the control parameters to be changed simultaneously with the change in FRDC_% are determined based on Voff (the potential of the edge ring 112a), which has a strong correlation with C_ER (the etching amount at the substrate center). Specifically, the control unit 2 examines the correlation between FRDC_% and Voff, and the correlation between the control parameters and Voff, and selects control parameters that can cancel out the fluctuation in Voff when FEDC_V is changed.

[0052] Based on the acquired data, control unit 2 calculates the values ​​of the control parameters to be changed simultaneously with the change in FRDC_% (step S103). Control unit 2 uses the FRDC_% adjustment amount a, the rate (slope) b of Voff increasing relative to FRDC_%, and the rate (slope) c of Voff increasing relative to HF_pw to derive a formula for calculating the value of the control parameter using the FRDC_% adjustment amount a as input. Control unit 2 calculates the value of the control parameter using the derived formula.

[0053] The control unit 2 stores the selected types of control parameters and the calculated values ​​of the control parameters in the storage unit 2a2. Alternatively, the control unit 2 may embed the values ​​of the control parameters in a manufacturing recipe for manufacturing a desired substrate. The control unit 2 may also notify an external device of the selected types of control parameters and the calculated values ​​of the control parameters via the communication interface 2a3. The notification destination may be another plasma processing device that performs the same steps as the plasma processing device 1, or may be a management server that manages these plasma processing devices.

[0054] After executing the check recipe using the dummy substrate, the control unit 2 executes the following processing in accordance with the manufacturing recipe for manufacturing the desired substrate.

[0055] The control unit 2 starts the manufacturing process of the substrate in accordance with the manufacturing recipe (step S104). The control unit 2 counts the RF application time using a built-in clock and determines whether the set time has elapsed (step S105). If the set time has not elapsed (S105: NO), the control unit 2 waits until the set time has elapsed.

[0056] If it is determined that the set time has elapsed (S105: YES), the control unit 2 changes the FRDC_% and also changes the values ​​of the control parameters that should be changed simultaneously with the FRDC_% in accordance with the calculation results of step S103 (step S106). Since the control parameter values ​​are calculated in step S103 so as to cancel out fluctuations in Voff, changing the control parameter values ​​in accordance with the calculation results can suppress fluctuations in Voff. As a result, fluctuations in C_ER, which is highly correlated with Voff, can be suppressed.

[0057] The control unit 2 refers to the manufacturing recipe and determines whether or not to end the manufacturing process (step S107). If it is determined not to end the manufacturing process (S107: NO), the control unit 2 returns the process to step S105. If it is determined to end the manufacturing process (S107: YES), the control unit 2 ends the process according to this flowchart.

[0058] FIG. 7 is a graph showing the simulation results for a specific step. FIG. 7 shows the simulation results for a specific step (e.g., the step of cutting an organic film). Of the two graphs shown in FIG. 7, the graph on the left shows the change in C_ER versus FRDC_%, and the graph on the right shows the change in HF-pw versus FRDC_%. In each graph, black circles indicate the simulation results when HF_pw was not changed, and white circles indicate the simulation results when HF_pw was changed.

[0059] In the above steps, when HF_pw was not changed in response to the adjustment of FRDC_%, C_ER fluctuated significantly, as shown by the black circles in the graph on the left. For example, a 10.3% increase in C_ER was observed for a 25% adjustment amount (FRDC_%). In contrast, when HF_pw was selected as the control parameter and HF_pw was decreased, as shown by the white circles in the graph on the right, the fluctuations in C_ER were suppressed, and C_ER increased by 2.9% for a 25% adjustment amount (FRDC_%).

[0060] FIG. 8 is a graph showing the simulation results for another step (a step of cutting the silicon film). Of the two graphs shown in FIG. 8, the graph on the left shows the change in C_ER relative to FRDC_%, and the graph on the right shows the change in LF-pw relative to FRDC_%. In each graph, black circles indicate the simulation results when LF_pw was not changed, and white circles indicate the simulation results when LF_pw was changed.

[0061] In the above steps, when LF_pw was not changed in response to the adjustment of FRDC_%, C_ER fluctuated significantly, as shown by the black circles in the graph on the left. For example, a 1.9% increase in C_ER was observed for a 25% adjustment amount (FRDC_%). In contrast, when LF_pw was selected as the control parameter and LF_pw was decreased as shown by the white circles in the graph on the right, the fluctuations in C_ER were suppressed, and C_ER decreased by 1.0% for a 25% adjustment amount (FRDC_%).

[0062] As described above, in the embodiment, when FRDC_% is increased in accordance with the RF application time, the control parameter to be changed for each step of each process recipe is selected based on the potential of the edge ring 112a, which has a strong correlation with C_ER, and the value of the selected control parameter is changed simultaneously with the adjustment of FRDC_%, thereby making it possible to suppress fluctuations in C_ER (etching rate at the center of the substrate).

[0063] In the embodiment, the RF power is adjusted to suppress fluctuations in C_ER (etching rate at the center of the substrate), but the configuration may also be such that fluctuations in C_ER are suppressed by adjusting parameters related to pulse signals, such as the duty ratio and period, in addition to the RF power.

[0064] Furthermore, in the embodiment, either HF_pw or LF_pw is selected as the control parameter to be adjusted, but since there are plasma processing systems that perform plasma processing using one type of HF and two types of LF, it is also possible to select at least one control parameter to be adjusted from three types of control parameters.

[0065] In the first embodiment, the variable DC power supply 33 is disclosed as a means for adjusting the sheath thickness above the edge ring 112a. Alternatively, a pulsed DC voltage may be supplied to the edge ring 112a to adjust the sheath thickness. In this case, the control parameters may be adjusted simultaneously with the change in the pulsed DC voltage to suppress fluctuations in C_ER (the etching rate at the center of the substrate).

[0066] Furthermore, an adjustment circuit for adjusting the impedance of the edge ring 112 a may be provided, and the sheath thickness may be adjusted by adjusting the impedance of the edge ring 112 a. In this case, a control parameter may be adjusted simultaneously with the change in impedance to suppress fluctuations in C_ER (etching rate at the center of the substrate).

[0067] Furthermore, the sheath thickness may be adjusted by moving the edge ring 112a vertically. In this case, the control parameters may be adjusted simultaneously with the vertical movement of the edge ring 112a to suppress fluctuations in C_ER (etching rate at the center of the substrate).

[0068] In the first embodiment, the control unit 2 is configured to execute the correction process, but the correction process may be executed by an external server such as a cloud server that is capable of communicating with the control unit 2. Furthermore, the program installed in the control unit 2 may be provided as a program product.

[0069] The embodiments disclosed herein are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the claims, not by the above meaning, and is intended to include all modifications within the meaning and scope of the claims.

[0070] In the embodiment, an example of application to a capacitively coupled plasma processing apparatus 1 has been described, but the present invention is not limited to capacitively coupled plasma processing apparatuses, and can be applied to any type of plasma processing apparatus, including Inductively Coupled Plasma (ICP), Radial Line Slot Antenna (RLSA), Electron Cyclotron Resonance Plasma (ECR), and Helicon Wave Plasma (HWP).

[0071] In the embodiment, a wafer W has been described as an example of a substrate to be processed, but the substrate to be processed is not limited to a wafer W and may be various substrates used in FPDs (Flat Panel Displays), printed circuit boards, etc.

[0072] REFERENCE SIGNS LIST 1 Plasma processing apparatus 2 Control unit 2a Computer 2a1 Processing unit 2a2 Memory unit 2a3 Communication interface 10 Plasma processing chamber 11 Substrate support unit 20 Gas supply unit 30 Power supply 31 RF power supply 31a First RF generation unit 31b Second RF generation unit 32 DC power supply 32a First DC generation unit 32b Second DC generation unit 33 Variable DC power supply 34 Electrometer 112 Ring assembly 112a Edge ring 112b Cover ring

Claims

1. A plasma processing apparatus which performs plasma processing on a substrate placed on a mounting table, comprising: an annular member arranged around the substrate; an adjustment unit which adjusts a sheath thickness on the annular member; a measurement unit which measures the electric potential of the annular member; and a control unit which controls values ​​of multiple control parameters in the plasma processing, wherein the control unit acquires data which indicates an amount of fluctuation in the electric potential when an adjustment amount in the adjustment unit is changed, and data which indicates an amount of fluctuation in the electric potential when the value of the control parameter is changed for each control parameter, and determines, based on the acquired data, the type of control parameter which should be changed simultaneously with the change in the adjustment amount, and calculates the value of the control parameter so as to suppress the amount of fluctuation in the electric potential which accompanies the change in the adjustment amount.

2. The plasma processing apparatus of claim 1, wherein the plurality of control parameters include a source power supplied to a plasma generation source and a bias power supplied to the mounting table, and the control unit selects at least one of the source power and the bias power as a control parameter to be changed simultaneously with the change in the adjustment amount.

3. The plasma processing apparatus according to claim 1, wherein the control unit determines the type of control parameter to be changed simultaneously with the change in the adjustment amount for each step of a process recipe that defines a procedure for the plasma processing, and calculates the value of the determined control parameter.

4. The plasma processing apparatus of claim 1, wherein the control unit calculates the value of the control parameter based on the correlation between the adjustment amount and the amount of fluctuation in the potential and the correlation between the value of the control parameter and the amount of fluctuation in the potential so as to suppress the amount of fluctuation in the potential associated with a change in the adjustment amount.

5. The plasma processing apparatus according to claim 1, wherein the control unit uses the acquired data as training data and calculates the value of the control parameter using a learning model that has been trained to output the value of the control parameter in response to the input of the adjustment amount.

6. The plasma processing apparatus of claim 1, wherein the control unit acquires data indicating the amount of change in the potential when the adjustment amount in the adjustment unit is changed by plasma processing using a dummy substrate, and data indicating the amount of change in the potential when the value of the control parameter is changed for each control parameter.

7. The plasma processing apparatus according to any one of claims 1 to 6, wherein the adjustment unit includes a power supply that supplies power to the annular member.

8. A plasma processing apparatus according to any one of claims 1 to 6, wherein the adjustment unit includes a drive source that drives the annular member in the up and down direction.

9. The plasma processing apparatus according to any one of claims 1 to 6, wherein the adjustment section includes an impedance circuit that adjusts the impedance in the annular member.

10. A control method for a plasma processing apparatus that performs plasma processing on a substrate placed on a mounting table, the control method comprising: acquiring, from a plasma processing apparatus comprising: an annular member arranged around the substrate; an adjustment unit that adjusts a sheath thickness on the annular member; a measurement unit that measures the potential of the annular member; and a control unit that controls values ​​of a plurality of control parameters in the plasma processing, data indicating an amount of fluctuation in the potential when an adjustment amount in the adjustment unit is changed and data indicating an amount of fluctuation in the potential when the value of the control parameter is changed for each control parameter, determining, based on the acquired data, a type of control parameter that should be changed simultaneously with the change in the adjustment amount, and calculating a value of the control parameter so as to suppress the amount of fluctuation in the potential accompanying the change in the adjustment amount.

11. A control program for a plasma processing apparatus that performs plasma processing on a substrate placed on a mounting table, the control program causing a computer to execute the following processes: from a plasma processing apparatus comprising: an annular member arranged around the substrate; an adjustment unit that adjusts a sheath thickness on the annular member; a measurement unit that measures the potential of the annular member; and a control unit that controls values ​​of a plurality of control parameters in the plasma processing; acquiring data indicating an amount of fluctuation in the potential when an adjustment amount in the adjustment unit is changed, and data indicating an amount of fluctuation in the potential when the value of the control parameter is changed for each control parameter; determining, based on the acquired data, a type of control parameter that should be changed simultaneously with the change in the adjustment amount; and calculating a value of the control parameter so as to suppress the amount of fluctuation in the potential accompanying the change in the adjustment amount.