Plasma processing device and control method

Abstract

Disclosed is a plasma processing device that includes a chamber, a substrate support part, and an upper electrode. The substrate support part is disposed inside the chamber. The upper electrode has a plurality of gas holes and is provided above the substrate support part. In an ON period, high-frequency source power is supplied from a high-frequency power supply to a high-frequency electrode, and electrical bias is supplied from a first bias power supply to the substrate support part. In a first period including the start point of the ON period, a negative voltage having a voltage level of a first absolute value is applied to the upper electrode from a second bias power supply. In a second period after the first period in the ON period, a negative voltage having a voltage level of a second absolute value is applied to the upper electrode from the second bias power supply. The first absolute value is less than the second absolute value.

Description

Plasma processing apparatus and control method

[0001] SUMMARY OF THE INVENTION An exemplary embodiment of the present disclosure relates to a plasma processing apparatus and a control method.

[0002] Plasma processing apparatuses are used in plasma processing of substrates. A capacitively coupled plasma processing apparatus is known as one type of plasma processing apparatus. The capacitively coupled plasma processing apparatus includes a chamber, a substrate support, and an upper electrode. The substrate support is disposed within the chamber. The upper electrode is disposed above the substrate support. The plasma processing apparatus described in Patent Document 1 supplies pulsed source high-frequency power for plasma generation and bias high-frequency power for ion attraction to the substrate support, and applies a negative voltage to the upper electrode.

[0003] JP 2010-171320 Public Relations

[0004] The present disclosure provides a technique for suppressing discharge within an upper electrode of a plasma processing apparatus.

[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, an upper electrode, a radio frequency power supply, a first bias power supply, a second bias power supply, and a controller. The substrate support is disposed within the chamber. The upper electrode is disposed above the substrate support. The upper electrode has a plurality of gas holes formed therein for introducing gas into the chamber. The radio frequency power supply is electrically coupled to the radio frequency electrode, which is the substrate support or the upper electrode, and is configured to generate a source radio frequency power for generating plasma from the gas within the chamber. The first bias power supply is electrically coupled to the substrate support and is configured to generate an electrical bias for attracting ions within the chamber to a substrate on the substrate support. The second bias power supply is configured to apply a negative voltage to the upper electrode. The controller controls the radio frequency power supply to supply the source radio frequency power to the radio frequency electrode during an ON period. The controller controls the first bias power supply to supply an electrical bias to the substrate support during the ON period. The control unit controls the second bias power supply to apply a negative voltage having a first absolute value to the upper electrode during a first period including the start of the ON period, and controls the second bias power supply to apply a negative voltage having a second absolute value to the upper electrode during a second period after the first period within the ON period, the first absolute value being smaller than the second absolute value.

[0006] According to one exemplary embodiment, a technique for suppressing electrical discharges in an upper electrode of a plasma processing apparatus is provided.

[0007] 3A and 3B are diagrams for explaining an example of the configuration of a capacitively coupled plasma processing apparatus; FIG. 3 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment; (a) and (b) of FIG. 3 are diagrams each showing an example of a waveform of an electric bias; FIG. 3 is a timing chart related to a plasma processing apparatus according to an exemplary embodiment; FIG. 3 is a flowchart showing a control method of a plasma processing apparatus according to an exemplary embodiment; FIG. 3 is a diagram schematically showing a plasma processing apparatus according to another exemplary embodiment; FIG. 3 is a timing chart related to a plasma processing apparatus according to another exemplary embodiment; and FIG. 3 is a flowchart showing a control method of a plasma processing apparatus according to another exemplary embodiment.

[0008] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[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.

[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.

[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.

[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 voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generator for generating the sequence of voltage pulses 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 voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. 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 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.

[0023] 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. This 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 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).

[0024] Reference will now be made to Fig. 2, which is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. As shown in Fig. 2, the plasma processing apparatus 1 includes the above-described upper electrode 14. In one embodiment, the upper electrode 14 includes a top plate 141 and a cooling plate 142.

[0025] The top plate 141 contacts the plasma processing space 10s and defines the plasma processing space 10s from above. The top plate 141 is made of a conductive material. The top plate 141 is made of, for example, silicon. The cooling plate 142 is provided on the top plate 141 and supports it. The cooling plate 142 is formed by forming a dielectric film, such as aluminum oxide, on the surface of a base material made of, for example, aluminum. The cooling plate 142 has a refrigerant flow path 142f formed therein. A refrigerant is supplied to the refrigerant flow path 142f from a chiller unit 60 provided outside the chamber 10. The refrigerant supplied to the refrigerant flow path 142f is returned to the chiller unit 60. The top plate 141 is cooled by supplying a refrigerant to the refrigerant flow path 142f.

[0026] The cooling plate 142 provides the gas diffusion chamber 13b. The top plate 141 and the cooling plate 142 provide a plurality of gas holes, which are the above-mentioned plurality of gas inlets 13c. The plurality of gas holes extend from the gas diffusion chamber 13b through the cooling plate 142 and the top plate 141 and open toward the plasma processing space 10s.

[0027] The plasma processing apparatus 1 includes a radio frequency power supply 50, a first bias power supply 51, and a second bias power supply 52. ​​The radio frequency power supply 50 is the first RF generating unit 31a and is electrically coupled to a radio frequency electrode. The radio frequency electrode is the above-mentioned lower electrode of the substrate support 11 or the upper electrode 14. The radio frequency power supply 50 is configured to generate source radio frequency power as a source RF signal for generating plasma from gas within the chamber 10. The radio frequency power supply 50 is electrically connected to the radio frequency electrode via a matching unit 50m. The matching unit 50m includes a matching circuit for matching the impedance of the load of the radio frequency power supply 50 to the output impedance of the radio frequency power supply 50.

[0028] The first bias power supply 51 is electrically coupled to the substrate support 11 (e.g., the lower electrode described above). The first bias power supply 51 is configured to generate an electric bias EB for attracting ions in the plasma in the chamber 10 to the substrate W on the substrate support 11. The electric bias EB has a bias frequency. The bias frequency has a frequency in the range of 100 kHz to 60 MHz. The bias frequency is, for example, 400 kHz.

[0029] The first bias power supply 51 may be the second RF generator 31b described above. In this case, the first bias power supply 51 is configured to generate the bias RF power LF, which is the bias RF signal described above, as the electrical bias EB. In this case, the first bias power supply 51 is electrically connected to the substrate support 11 via a matching device 51m. The matching device 51m includes a matching circuit for matching the impedance of the load of the first bias power supply 51 to the output impedance of the first bias power supply 51. The bias RF power LF is power having a sinusoidal waveform with a bias frequency, as shown in FIG. 3A, and is generated periodically. The waveform period CY of the bias RF power LF has a time length that is the reciprocal of the bias frequency.

[0030] Alternatively, the first bias power supply 51 may include the first DC generator 32a. In this case, the first bias power supply 51 is configured to periodically generate a voltage pulse VP, which is the first DC signal, as the electric bias EB. In this case, the plasma processing apparatus 1 does not need to include the matching unit 51m, and the first bias power supply 51 is electrically connected to the substrate support 11 (e.g., the lower electrode) without the matching unit 51m. The voltage pulse VP is periodically generated at a time interval of a waveform period CY, as shown in FIG. 3B. In the example of FIG. 3B, the voltage pulse VP is a negative voltage or negative DC voltage pulse. However, the polarity of the voltage pulse VP is not limited to negative polarity as long as ions can be attracted from the plasma to the substrate W.

[0031] The second bias power supply 52 includes the second DC generator 32b described above and is electrically coupled to the upper electrode 14. The second bias power supply 52 is configured to apply a negative voltage UEV to the upper electrode 14. The second bias power supply 52 may include a variable DC power supply.

[0032] 2 and 3, reference will now be made to FIG. 4. FIG. 4 is a timing chart relating to a plasma processing apparatus according to an exemplary embodiment. The control unit 2 controls the ON period P ＯＮ During the ON period P, the high frequency power supply 50 is controlled to supply source high frequency power HF to the high frequency electrode. ＯＮ The power level of the source high frequency power HF at is, for example, 1000 W or more.

[0033] In addition, the control unit 2 ＯＮ When the electric bias EB is a bias high frequency power LF, the first bias power supply 51 is controlled to supply an electric bias EB to the substrate support 11 (for example, the lower electrode) during the ON period P ＯＮ The power level of the bias high frequency power LF in the ON period P is, for example, 3000 W or more and 100,000 W or less. ＯＮ The voltage level of the voltage pulse VP at is, for example, a level in the range between −3000V and −10000V.

[0034] As shown in FIG. 4, the control unit 2 ＯＮ A first period P including the start time of １ At this voltage level V １ is the first absolute value |V １ The second bias power supply 52 is controlled to apply a negative voltage UEV having |V １ | is, for example, greater than 0 V and equal to or less than 300 V. １ is, for example, 200 V. １ The first period P may have a time length four times or more the waveform period CY. １ The first period P may have a time length of 8 times or less or 10 times or less of the waveform period CY.１ is the ON period P ＯＮ , and the ON period P ＯＮ It may start before or just before the start of

[0035] In addition, the control unit 2 ＯＮ The first period P １ The second period P ２ At this voltage level V ２ is the second absolute value |V ２ The second bias power supply 52 is controlled to apply a negative voltage UEV having a first absolute value |V １ | is the second absolute value |V ２ | is smaller than |V ２ | is, for example, 100 V or more and 1000 V or less. ２ | is, for example, 500V.

[0036] In one embodiment, the ON period P ＯＮ is the OFF period P ＯＦＦ The control unit 2 may alternately operate during the OFF period P ＯＦＦ In this embodiment, the control unit 2 controls the high frequency power supply 50 and the first bias power supply 51 to stop the supply of the source high frequency power HF and the supply of the electric bias EB. That is, in one embodiment, the control unit 2 controls the high frequency power supply 50 to periodically supply pulses of the source high frequency power HF, and the control unit 2 controls the first bias power supply 51 to periodically supply pulses of the electric bias EB. The pulses of the source high frequency power HF and the pulses of the electric bias EB are periodically supplied at a pulse frequency of, for example, 1 kHz or more and 20 kHz or less. That is, during the ON period P ＯＮ appears periodically at a time interval equal to the reciprocal of the pulse frequency.

[0037] The control unit 2 ＯＦＦ In the OFF period P, the second bias power supply 52 may be controlled to apply a negative voltage UEV to the upper electrode 14. ＯＦＦ The voltage level V of the negative voltage UEV at ３ The third absolute value of |V ３ | is the second absolute value |V ２| may be larger than |V ３ is, for example, 300 V or more and 1000 V or less. ３ | is, for example, 1000V.

[0038] In the plasma processing apparatus 1, the ON period P ＯＮ , a negative voltage UEV is applied to the upper electrode 14. This increases the distance between the plasma and the upper electrode 14, and prevents the temperature of the upper electrode 14 from increasing.

[0039] In addition, the first period P １ the first absolute value |V １ | is the second period P ２ the second absolute value of the voltage level of the negative voltage UEV at |V ２ Therefore, the first period P １ If the voltage level of the negative voltage UEV at ＯＮ Therefore, abnormal discharge in the gas holes of the upper electrode 14 immediately after the start of discharge is suppressed.

[0040] In addition, the OFF period P ＯＦＦ Since the negative voltage UEV is applied to the upper electrode 14 even during the OFF period P ＯＦＦ In this state, the upper electrode 14 is neutralized.

[0041] A control method for a plasma processing apparatus according to one exemplary embodiment will be described below with reference to Fig. 5. Fig. 5 is a flowchart of the control method for a plasma processing apparatus according to one exemplary embodiment. The control method shown in Fig. 5 (hereinafter referred to as "method MT") includes steps STa to STd.

[0042] The process STa is an ON period P ＯＮ In the step STa, in order to generate plasma from the gas in the chamber 10 of the plasma processing apparatus 1, a source high frequency power HF is supplied from the high frequency power supply 50 to the high frequency electrode.

[0043] The process STb is an ON period P ＯＮIn the step STb, an electric bias EB is supplied from the first bias power supply 51 to the substrate support 11 (e.g., the lower electrode) in order to attract ions in the chamber 10 to the substrate W on the substrate support 11.

[0044] The process STc is performed during the first period P １ In step STc, the voltage level V １ is the first absolute value |V １ A negative voltage UEV having a value | is applied to the upper electrode 14 from a second bias power supply 52 .

[0045] The process STd is performed during the second period P ２ In step STd, the voltage level V ２ is the second absolute value |V ２ A negative voltage UEV having a first absolute value |V １ | is the second absolute value |V ２ |Smaller than.

[0046] In the method MT, the ON period P ＯＮ is OFF period P ＯＦＦ In this case, the method MT further includes steps STe, STf, and STJ.

[0047] The process STe and the process STf are performed during the OFF period P ＯＦＦ In step STe, the supply of the source high frequency power HF and the electric bias EB is stopped. In step STf, a negative voltage UEV is applied to the upper electrode 14 from the second bias power supply 52. ​​The voltage level V of the negative voltage UEV in step STf ３ The third absolute value of |V ３ | is the second absolute value |V ２ |It may be larger.

[0048] In the step STJ, it is determined whether or not a stop condition is satisfied. The stop condition is satisfied, for example, when the number of repetitions of the steps STa to STf reaches a predetermined number. If it is determined that the stop condition is not satisfied in the step STJ, the processing is repeated again from the step STa. If it is determined that the stop condition is satisfied in the step STJ, the method MT ends.

[0049] A plasma processing apparatus according to another exemplary embodiment will be described below with reference to Fig. 6. Fig. 6 is a diagram schematically illustrating a plasma processing apparatus according to another exemplary embodiment. The plasma processing apparatus 1B shown in Fig. 6 will be described below from the viewpoint of differences from the plasma processing apparatus 1.

[0050] The plasma processing apparatus 1B further includes a detector 70. The detector 70 is configured to acquire a detection signal that varies from its normal magnitude when there is a possibility of discharge in the upper electrode 14. The detection period of the detection signal is an ON period P ＯＮ The ON period P, which is the detection period of the detection signal, may include the whole or a part of the ON period P. ＯＮ A part of the ON period P ＯＮ The detection period of the detection signal may include the start time of the OFF period P ＯＦＦ The detection signal may further include at least a part of the following. The detection signal is input to the control unit 2.

[0051] The detection signal may be a signal representing the emission intensity at a monitor gas hole among the multiple gas holes (i.e., the multiple gas inlets 13c) in the upper electrode 14. In this case, the detector 70 includes an optical sensor 71s configured to measure the intensity of the emission at the monitor gas hole (hereinafter referred to as "emission intensity"). An optical fiber extends between the optical sensor 71s and the monitor gas hole, optically connecting the optical sensor 71s and the monitor gas hole.

[0052] Alternatively, the detection signal may be a signal representing the potential or current value of the upper electrode 14. In this case, the detector 70 includes an electric sensor 72s configured to measure the potential or current value of the upper electrode 14. The electric sensor 72s is electrically connected to the upper electrode 14.

[0053] In the plasma processing apparatus 1B, the control unit 2 executes a first control when the detection signal determines that there is no possibility of discharge at the upper electrode 14, and executes a second control when the detection signal determines that there is a possibility of discharge at the upper electrode 14.

[0054] The control unit 2 may determine that there is a possibility of discharge in the upper electrode 14 when the emission intensity in the monitor gas hole, the potential of the upper electrode 14, or the current value in the upper electrode 14 is equal to or greater than a threshold value, and may execute the second control. In other cases, the control unit 2 executes the first control.

[0055] Alternatively, the control unit 2 may determine that there is a possibility of discharge in the upper electrode 14 when the emission intensity in the monitor gas hole, the potential of the upper electrode 14, or the difference between the current value in the upper electrode 14 and the corresponding value in a normal state is equal to or greater than a threshold value, and execute the second control. In other cases, the control unit 2 executes the first control.

[0056] The first control executed by the control unit 2 is as follows: ＯＮ over the voltage level V ２ is the second absolute value |V ２ The method includes controlling the second bias power supply 52 to apply a negative voltage UEV having a value | to the upper electrode 14 .

[0057] The second control executed by the control unit 2 is, as shown in FIG. １ At this voltage level V １ is the first absolute value |V １ The second control performed by the control unit 2 includes controlling the second bias power supply 52 to apply a negative voltage UEV having a value | to the upper electrode 14. Also, as shown in FIG. ２ At this voltage level V ２ is the second absolute value |V ２ The method includes controlling the second bias power supply 52 to apply a negative voltage UEV having a value | to the upper electrode 14 .

[0058] According to this plasma processing apparatus 1B, it is possible to control the voltage applied to the upper electrode 14 by the first control without performing the second control, which is unnecessary when there is no possibility of discharge at the upper electrode 14.

[0059] A control method for a plasma processing apparatus according to another exemplary embodiment will be described below with reference to Fig. 8. Fig. 8 is a flowchart of a control method for a plasma processing apparatus according to another exemplary embodiment. The control method shown in Fig. 8 (hereinafter referred to as "method MTB") will be described below from the perspective of differences from method MT.

[0060] Method MTB further includes step STJB, in which the control unit 2 determines whether there is a possibility of discharge at the upper electrode 14 based on the detection signal acquired by the detector 70. For the determination of the possibility of discharge at the upper electrode 14, please refer to the above description of the plasma processing apparatus 1B.

[0061] In step STJB, if it is determined that there is no possibility of discharge at the upper electrode 14, the above-described first control is executed in step ST1. After step ST1, the processing may proceed to step STe.

[0062] If it is determined in step STJB that there is a possibility of discharge at the upper electrode 14, the above-described second control is executed in step ST2. The second control includes steps STc and STd of the method MT. After step ST2, the processing may proceed to step STe.

[0063] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0064] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E18] below.

[0065] [E1] A plasma processing apparatus comprising: a chamber; a substrate support disposed within the chamber; an upper electrode disposed above the substrate support, the upper electrode having a plurality of gas holes formed therein for introducing gas into the chamber; a radio frequency power supply electrically coupled to the substrate support or the radio frequency electrode that is the upper electrode, and configured to generate a source radio frequency power for generating plasma from the gas within the chamber; a first bias power supply electrically coupled to the substrate support and configured to generate an electric bias for attracting ions within the chamber to a substrate on the substrate support; a second bias power supply configured to apply a negative voltage to the upper electrode; and a controller, wherein the controller: controls the radio frequency power supply to supply the source radio frequency power to the radio frequency electrode during an ON period; controls the first bias power supply to supply the electric bias to the substrate support during the ON period; and controls the second bias power supply to apply the negative voltage, the voltage level of which has a first absolute value, to the upper electrode during a first period that includes a start point of the ON period; and controlling the second bias power supply so as to apply the negative voltage, the voltage level of which has a second absolute value, to the upper electrode during a second period after the first period within the ON period, wherein the first absolute value is smaller than the second absolute value.

[0066] [E2] The plasma processing apparatus according to E1, wherein the electrical bias is a bias high frequency power having a bias frequency or a voltage pulse generated periodically at a time interval of the reciprocal of the bias frequency, and the first period has a length from the start point of time that is four or more times a period having a time length of the reciprocal of the bias frequency.

[0067] [E3] The plasma processing apparatus according to E2, wherein the first period has a length that is 8 times or less or 10 times or less of the period.

[0068] [E4] The plasma processing apparatus according to any one of E1 to E3, wherein the ON periods and OFF periods appear alternately, and the control unit is configured to control the high frequency power supply and the first bias power supply so as to stop the supply of the high frequency power and the supply of the electric bias during the OFF periods.

[0069] [E5] The plasma processing apparatus according to E4, wherein the control unit is configured to control the second bias power supply so as to apply the negative voltage, whose voltage level has a third absolute value greater than the second absolute value, to the upper electrode during the OFF period.

[0070] [E6] The plasma processing apparatus according to any one of E1 to E5, wherein the upper electrode includes: a top plate in contact with the plasma processing space in the chamber; and a cooling plate having a coolant flow path therein and provided on the top plate.

[0071] [E7] The plasma processing apparatus according to E6, wherein the top plate is made of silicon.

[0072] [E8] A control method comprising the steps of: supplying a source radio frequency power from a radio frequency power supply to a radio frequency electrode which is a substrate support part in a chamber or an upper electrode arranged above the substrate support part, in order to generate plasma from a gas in the chamber of a plasma processing apparatus during an ON period; supplying an electric bias from a first bias power supply to the substrate support part in order to attract ions in the chamber to a substrate on the substrate support part, in the ON period; applying a negative voltage having a voltage level of a first absolute value from a second bias power supply to the upper electrode during a first period including a start point of the ON period; and applying the negative voltage having a voltage level of a second absolute value from the second bias power supply to the upper electrode during a second period after the first period within the ON period, wherein the first absolute value is smaller than the second absolute value.

[0073] [E9] A plasma processing system comprising: a chamber; a substrate support disposed within the chamber; an upper electrode disposed above the substrate support, the upper electrode having a plurality of gas holes formed therein for introducing gas into the chamber; a radio frequency power supply electrically coupled to the substrate support or the radio frequency electrode that is the upper electrode, and configured to generate a source radio frequency power for generating plasma from a gas in the chamber; a first bias power supply electrically coupled to the substrate support and configured to generate an electric bias for attracting ions in the chamber to a substrate on the substrate support; a second bias power supply configured to apply a negative voltage to the upper electrode; a detector configured to obtain a detection signal that is a signal representing an emission intensity at a monitor gas hole among the plurality of gas holes or a signal representing a potential or a current value of the upper electrode; and a control unit, wherein the control unit controls the radio frequency power supply to supply the source radio frequency power to the radio frequency electrode during an ON period, and controls the first bias power supply to supply the electric bias to the substrate support during the ON period, and performs a first control when it is determined from the detection signal that there is no possibility of discharge at the upper electrode, and executing second control when it is determined from the detection signal that there is a possibility of discharge at the upper electrode, wherein the second control includes: controlling the second bias power supply to apply the negative voltage, the voltage level of which has a first absolute value, to the upper electrode during a first period including a start point of the ON period; and controlling the second bias power supply to apply the negative voltage, the voltage level of which has a second absolute value, to the upper electrode during a second period after the first period within the ON period; and the first control includes controlling the second bias power supply to apply the negative voltage, the voltage level of which has the second absolute value, to the upper electrode throughout the ON period, wherein the first absolute value is smaller than the second absolute value.

[0074] [E10] The plasma processing apparatus according to E9, wherein the electrical bias is a bias high frequency power having a bias frequency or a voltage pulse generated periodically at a time interval of the reciprocal of the bias frequency, and the first period has a length four or more times a period having a time length of the reciprocal of the bias frequency from the start point.

[0075] [E11] The plasma processing apparatus according to E10, wherein the first period has a length that is 8 times or less or 10 times or less of the period.

[0076] [E12] The plasma processing apparatus according to any one of E9 to E11, wherein the ON periods and OFF periods appear alternately, and the control unit is configured to control the high frequency power supply and the first bias power supply so as to stop the supply of the high frequency power and the supply of the electric bias during the OFF periods.

[0077] [E13] The plasma processing apparatus according to E12, wherein the control unit is configured to control the second bias power supply so as to apply the negative voltage, whose voltage level has a third absolute value greater than the second absolute value, to the upper electrode during the OFF period.

[0078] [E14] The plasma processing apparatus according to any one of E9 to E13, wherein the upper electrode includes: a top plate in contact with the plasma processing space in the chamber; and a cooling plate having a coolant flow path therein and provided on the top plate.

[0079] [E15] The plasma processing apparatus according to E14, wherein the top plate is made of silicon.

[0080] [E16] The plasma processing apparatus according to any one of E9 to E15, wherein the control unit is configured to execute the second control when the emission intensity, the potential, or the current value identified from the detection signal is equal to or greater than a threshold value.

[0081] [E17] The plasma processing apparatus according to any one of E9 to E15, wherein the control unit is configured to execute the second control when a difference value between the emission intensity, the potential, or the current value identified from the detection signal and a normal value of the emission intensity, the potential, or the current value is equal to or greater than a threshold value.

[0082] [E18] A plasma processing apparatus comprising: a step of supplying a source high frequency power from a high frequency power supply to a substrate support part in the chamber or a high frequency electrode which is an upper electrode arranged above the substrate support part, in order to generate plasma from a gas in the chamber during an ON period; a step of supplying an electric bias from a first bias power supply to the substrate support part during the ON period, in order to attract ions in the chamber to a substrate on the substrate support part; a step of executing a first control when it is determined that there is no possibility of discharge at the upper electrode from a detection signal which is a signal representing an emission intensity at a monitor gas hole among a plurality of gas holes in the upper electrode for introducing gas into the chamber or a signal representing a potential or a current value of the upper electrode; and a step of executing a second control when it is determined that there is a possibility of discharge at the upper electrode from the detection signal, wherein the second control comprises: a step of applying a negative voltage having a voltage level of a first absolute value from a second bias power supply to the upper electrode during a first period including a start point of the ON period; applying the negative voltage, the voltage level of which has a second absolute value, from the second bias power supply to the upper electrode during a second period after the first period within the ON period, wherein the first control includes applying the negative voltage, the voltage level of which has the second absolute value, from the second bias power supply to the upper electrode during the ON period, wherein the first absolute value is smaller than the second absolute value.

[0083] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims.

[0084] 1... plasma processing apparatus, 2... control section, 10... chamber, 11... substrate support section, 14... upper electrode, 50... high frequency power supply, 51... first bias power supply, 52... second bias power supply

Claims

a first bias power supply electrically coupled to the substrate support and configured to generate an electrical bias for attracting ions in the chamber to a substrate on the substrate support; a second bias power supply configured to apply a negative voltage to the upper electrode; and a control unit, wherein the control unit: controls the radio frequency power supply to supply the source radio frequency power to the radio frequency electrode during an ON period; controls the first bias power supply to supply the electrical bias to the substrate support during the ON period; and controls the second bias power supply to apply the negative voltage, the voltage level of which has a first absolute value, to the upper electrode during a first period including a start point of the ON period; and controlling the second bias power supply to apply the negative voltage, the voltage level of which has a second absolute value, to the upper electrode during a second period following the first period within the ON period, wherein the first absolute value is smaller than the second absolute value.

2. The plasma processing apparatus according to claim 1, wherein the electrical bias is a bias high frequency power having a bias frequency or a voltage pulse generated periodically at a time interval of the inverse of the bias frequency, and the first period has a length four or more times a period having a time length of the inverse of the bias frequency from the start point.

3. The plasma processing apparatus according to claim 2, wherein the first period has a length equal to or less than 8 or 10 times the length of the period.

4. A plasma processing apparatus as described in any one of claims 1 to 3, wherein the ON periods appear alternately with OFF periods, and the control unit is configured to control the high frequency power supply and the first bias power supply so as to stop the supply of the high frequency power and the supply of the electrical bias during the OFF periods.

5. The plasma processing apparatus of claim 4, wherein the control unit is configured to control the second bias power supply so as to apply the negative voltage, the voltage level of which has a third absolute value greater than the second absolute value, to the upper electrode during the OFF period.

6. A plasma processing apparatus as claimed in any one of claims 1 to 3, wherein the upper electrode comprises: a top plate in contact with the plasma processing space in the chamber; and a cooling plate having a refrigerant flow path therein and provided on the top plate.

7. The plasma processing apparatus according to claim 6, wherein the top plate is made of silicon.

8. A control method comprising the steps of: supplying a source radio frequency power from a radio frequency power supply to a radio frequency electrode which is a substrate support part in a chamber or an upper electrode arranged above the substrate support part in order to generate plasma from a gas in a chamber of a plasma processing apparatus during an ON period; supplying an electric bias from a first bias power supply to the substrate support part in order to attract ions in the chamber to a substrate on the substrate support part during the ON period; applying a negative voltage having a voltage level with a first absolute value from a second bias power supply to the upper electrode during a first period including a start point of the ON period; and applying the negative voltage having a voltage level with a second absolute value from the second bias power supply to the upper electrode during a second period after the first period in the ON period, wherein the first absolute value is smaller than the second absolute value.

9. A device comprising: a chamber; a substrate support part disposed within the chamber; an upper electrode disposed above the substrate support part, the upper electrode having a plurality of gas holes formed therein for introducing a gas into the chamber; a radio frequency power supply electrically coupled to the substrate support part or the radio frequency electrode which is the upper electrode, and configured to generate a source radio frequency power for generating plasma from a gas in the chamber; a first bias power supply electrically coupled to the substrate support part and configured to generate an electric bias for attracting ions in the chamber to a substrate on the substrate support part; a second bias power supply configured to apply a negative voltage to the upper electrode; a detector configured to obtain a detection signal which is a signal representing an emission intensity at a monitor gas hole among the plurality of gas holes or a signal representing a potential or a current value of the upper electrode; and a control unit, wherein the control unit controls the radio frequency power supply to supply the source radio frequency power to the radio frequency electrode during an ON period, and controls the first bias power supply to supply the electric bias to the substrate support part during the ON period; and executes a first control when it is determined from the detection signal that there is no possibility of discharge at the upper electrode, and executing a second control when it is determined from the detection signal that there is a possibility of discharge at the upper electrode, wherein the second control includes: controlling the second bias power supply to apply the negative voltage, the voltage level of which has a first absolute value, to the upper electrode during a first period including a start point of the ON period; and controlling the second bias power supply to apply the negative voltage, the voltage level of which has a second absolute value, to the upper electrode during a second period after the first period within the ON period, wherein the first control includes controlling the second bias power supply to apply the negative voltage, the voltage level of which has the second absolute value, to the upper electrode throughout the ON period, wherein the first absolute value is smaller than the second absolute value.

10. The plasma processing apparatus according to claim 9, wherein the electrical bias is a bias high frequency power having a bias frequency or a voltage pulse generated periodically at a time interval of the inverse of the bias frequency, and the first period has a length four or more times a period having a time length of the inverse of the bias frequency from the start point.

11. The plasma processing apparatus according to claim 10, wherein the first period has a length equal to or less than eight or ten times the length of the period.

12. A plasma processing apparatus as described in any one of claims 9 to 11, wherein the ON periods appear alternately with OFF periods, and the control unit is configured to control the high frequency power supply and the first bias power supply so as to stop the supply of the high frequency power and the supply of the electrical bias during the OFF periods.

13. The plasma processing apparatus according to claim 12, wherein the control unit is configured to control the second bias power supply so as to apply the negative voltage, the voltage level of which has a third absolute value greater than the second absolute value, to the upper electrode during the OFF period.

14. A plasma processing apparatus as claimed in any one of claims 9 to 11, wherein the upper electrode comprises: a top plate in contact with the plasma processing space in the chamber; and a cooling plate having a coolant flow path therein and provided on the top plate.

15. The plasma processing apparatus according to claim 14, wherein the top plate is made of silicon.

16. A plasma processing apparatus according to any one of claims 9 to 11, wherein the control unit is configured to execute the second control when the emission intensity, the potential, or the current value determined from the detection signal is equal to or greater than a threshold value.

17. A plasma processing apparatus according to any one of claims 9 to 11, wherein the control unit is configured to execute the second control when a difference value between the emission intensity, the potential, or the current value identified from the detection signal and a normal value of the emission intensity, the potential, or the current value is equal to or greater than a threshold value.

18. A plasma processing apparatus comprising: a step of supplying a source high frequency power from a high frequency power supply to a high frequency electrode which is a substrate support part in the chamber or an upper electrode arranged above the substrate support part in order to generate plasma from a gas in the chamber during an ON period; a step of supplying an electric bias from a first bias power supply to the substrate support part during the ON period in order to attract ions in the chamber to a substrate on the substrate support part; a step of executing a first control when it is determined that there is no possibility of discharge in the upper electrode from a detection signal which is a signal representing an emission intensity in a monitor gas hole among a plurality of gas holes in the upper electrode for introducing gas into the chamber or a signal representing an electric potential or a current value of the upper electrode; and a step of executing a second control when it is determined that there is a possibility of discharge in the upper electrode from the detection signal, wherein the second control comprises: a step of applying a negative voltage having a voltage level of a first absolute value from a second bias power supply to the upper electrode during a first period including a start point of the ON period; applying the negative voltage, the voltage level of which has a second absolute value, from the second bias power supply to the upper electrode during a second period after the first period within the ON period, wherein the first control includes applying the negative voltage, the voltage level of which has the second absolute value, from the second bias power supply to the upper electrode during the ON period, the first absolute value being smaller than the second absolute value.

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