Plasma processing device, power supply system, control method, and program

Abstract

This disclosed plasma processing device includes a bias power supply, a first filter, a second filter, a switching circuit, and a control unit. The bias power supply periodically applies a voltage pulse to a substrate support part. The second filter has a cutoff frequency lower than the cutoff frequency of the first filter. The voltage pulse falls in the negative direction at the leading edge and rises at the trailing edge. The control unit connects the first filter between the bias power supply and the substrate support unit in a first period including the timing of the leading edge of the voltage pulse, and controls the switching circuit so as to connect the second filter between the bias power supply and the substrate support unit in a second period including the timing of the trailing edge of the voltage pulse.

Description

Plasma processing apparatus, power supply system, control method, and program

[0001] An exemplary embodiment of the present disclosure relates to a plasma processing apparatus, a power supply system, a control method, and a program.

[0002] Plasma processing apparatuses are used in plasma processing of substrates. One type of plasma processing apparatus includes a bias power supply electrically coupled to a substrate support. The bias power supply provides an electrical bias to the substrate support. The electrical bias may be a voltage pulse. In such plasma processing apparatuses, a filter circuit is connected between the bias power supply and the substrate support.

[0003] Special Publication No. 2023-536807

[0004] The present disclosure provides a technique for suppressing waveform blunting at the leading edge and positive overshoot at the trailing edge of a voltage pulse periodically applied to a substrate support part 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, a plasma generating unit, a bias power supply, a first filter, a second filter, a switching circuit, and a controller. The substrate support is disposed within the chamber. The plasma generating unit is configured to generate plasma from a gas within the chamber. The bias power supply is electrically coupled to the substrate support and configured to periodically apply voltage pulses to the substrate support to attract ions to a substrate on the substrate support. The first filter is a low-pass filter having a first cutoff frequency. The second filter is a low-pass filter having a second cutoff frequency lower than the first cutoff frequency. The voltage pulse falls negatively at its leading edge and rises negatively at its trailing edge. The controller controls the switching circuit to connect the first filter between the bias power supply and the substrate support during a first period including the timing of the leading edge of the voltage pulse. The controller controls the switching circuit to connect the second filter between the bias power supply and the substrate support during a second period including the timing of the trailing edge of the voltage pulse.

[0006] According to one exemplary embodiment, it is possible to suppress the blunting of the waveform at the leading edge of a voltage pulse that is periodically supplied to a substrate support portion of a plasma processing apparatus and the overshoot in the positive direction at the trailing edge.

[0007] FIG. 1 is a diagram for explaining an example of the configuration of a plasma processing system. FIG. 2 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus. FIG. 3 is a diagram showing a bias power supply, a first filter, a second filter, and a switching circuit of a plasma processing apparatus according to an exemplary embodiment. FIG. 4 is a diagram showing an example of the waveform of a voltage pulse applied to a substrate. FIG. 5 is a diagram showing an example of the waveform of a voltage pulse applied to a substrate. FIG. 6 is a flowchart of a control method according to an 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] FIG. 1 is a diagram illustrating an exemplary configuration of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0010] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), or surface wave plasma (SWP). Various types of plasma generators may be used, including alternating current (AC) plasma generators and direct current (DC) plasma generators. In one embodiment, the AC signal (AC power) used in the AC plasma generator has a frequency in the range of 100 kHz to 10 GHz. Thus, AC signals include radio frequency (RF) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0011] 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).

[0012] The following describes a configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0013] 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 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0014] 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.

[0015] 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 power supply 31 and / or a DC power supply 32, which will be 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, which will be 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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 at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

[0020] 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 processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generation unit 12. 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.

[0021] 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.

[0022] 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.

[0023] 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 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.

[0024] In various embodiments, 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.

[0025] 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.

[0026] Reference will now be made to FIG. 3 in addition to FIGS. 1 and 2. FIG. 3 is a diagram illustrating a bias power supply, a first filter, a second filter, and a switching circuit of a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus 1 includes a first DC generating unit 32a as a bias power supply. The plasma processing apparatus 1 further includes a first filter 51, a second filter 52, and a switching circuit 53. The bias power supply, the first filter 51, the second filter 52, and the switching circuit 53 constitute a power supply system. The power supply system may further include a control unit (e.g., control unit 2) configured to control the high-frequency power supply (first RF generating unit 31a) and / or the switching circuit 53.

[0027] The first DC generator 32a is electrically coupled to the lower electrode of the substrate support 11. The first DC generator 32a is configured to periodically apply voltage pulses to the substrate support 11 to attract ions from the plasma generated in the chamber 10 onto the substrate W on the substrate support 11.

[0028] 1 to 3, as well as FIGS. 4 and 5. Each of FIGS. 4 and 5 shows an example of the waveform of a voltage pulse applied to a substrate. In each of FIGS. 4 and 5, the dashed-dotted line indicates an ideal waveform of a voltage pulse generated by the first DC generating unit 32a. In FIG. 4, the solid line indicates the waveform of the voltage pulse VP transmitted to the substrate W. In FIG. 5, the solid line indicates the waveform of the voltage pulse VP transmitted to the substrate W after passing through the first filter, and the dotted line indicates the waveform of the voltage pulse VP transmitted to the substrate W after passing through the second filter.

[0029] The first DC generating unit 32a periodically generates a voltage pulse VP at a time interval of a waveform period CY (see FIG. 4). The bias frequency, which is the reciprocal of the time length of the waveform period CY, is, for example, 100 kHz or more and 13.56 MHz or less. In one example, the bias frequency is 400 kHz. The voltage pulse VP falls in the negative direction at its leading edge and rises in the positive direction at its trailing edge. The voltage pulse VP may be a negative voltage pulse or a negative DC voltage pulse.

[0030] The first filter 51 and the second filter 52 are configured such that one of them is selectively connected between the first DC generating unit 32a and the lower electrode of the substrate support 11. Each of the first filter 51 and the second filter 52 is a low-pass filter, and is configured to attenuate or block high-frequency power such as a source RF signal and / or a bias RF signal.

[0031] The first filter 51 has a first cutoff frequency. The second filter 52 has a second cutoff frequency. The second cutoff frequency is lower than the first cutoff frequency. The first cutoff frequency is lower than the frequency of the source RF power (i.e., source RF signal) supplied by the first RF generator 31a, which is a high-frequency power source, to generate plasma. The first cutoff frequency is, for example, not less than 13.56 MHz and not more than 40 MHz. The second cutoff frequency is, for example, not less than 1 MHz and not more than 10 MHz.

[0032] The switching circuit 53 is configured to selectively connect the first filter 51 or the second filter 52 between the first DC generating unit 32a and the lower electrode of the substrate support unit 11. The switching circuit 53 can be controlled by a control unit. The control unit that controls the switching circuit 53 can be the control unit 2. Below, an example in which the control unit 2 controls the switching circuit 53 will be described, but the switching circuit 53 may also be controlled by another control unit.

[0033] The control unit 2 controls the switching circuit 53 to connect the first filter 51 between the first DC generating unit 32a and the lower electrode of the substrate support unit 11 during a first period P1 that includes the timing tf of the leading edge of the voltage pulse VP. The control unit 2 controls the switching circuit 53 to connect the second filter 52 between the first DC generating unit 32a and the lower electrode of the substrate support unit 11 during a second period P2 that includes the timing tr of the trailing edge of the voltage pulse VP. Note that the waveform period CY can be composed of the first period P1 and the second period P2.

[0034] As shown by the dashed-dotted line in Fig. 5 , the voltage pulse VP is ideally a rectangular pulse. However, as shown by the dotted line in Fig. 5 , the waveform of the voltage pulse VP that passes through the second filter 52, which has a relatively low second cutoff frequency, and is transmitted to the substrate W is slowed from the rectangular pulse waveform. On the other hand, as shown by the solid line in Fig. 5 , the waveform of the voltage pulse VP that passes through the first filter 51, which has a relatively high first cutoff frequency, and is transmitted to the substrate W is relatively suppressed from slowing down. However, the waveform of the voltage pulse VP that passes through the first filter 51 and is transmitted to the substrate W has a relatively large overshoot in a period including the trailing edge. In contrast, as shown by the dotted line in Fig. 5 , the waveform of the voltage pulse VP that passes through the second filter 52 and is transmitted to the substrate W is suppressed from overshooting in a period including the trailing edge.

[0035] As described above, in the plasma processing apparatus 1, during the first period P1, the first filter 51, rather than the second filter 52, is connected between the first DC generator 32a and the lower electrode of the substrate support 11. Furthermore, during the second period P2, the second filter 52, rather than the first filter 51, is connected between the first DC generator 32a and the lower electrode of the substrate support 11. Therefore, according to the plasma processing apparatus 1, as shown in FIG. 4, for example, the waveform of the voltage pulse VP is suppressed from becoming blunted at the leading edge and the positive overshoot at the trailing edge is suppressed. Furthermore, in the plasma processing apparatus 1, the suppression of the waveform of the voltage pulse VP from becoming blunted at the leading edge promotes the acceleration of ions from the plasma to the substrate W. In other words, according to the plasma processing apparatus 1, it is possible to supply high-energy ions from the plasma to the substrate W. Furthermore, in the plasma processing apparatus 1, the suppression of the positive overshoot in the waveform of the voltage pulse VP suppresses the attenuation of the self-bias voltage.

[0036] In one embodiment, as shown in FIG. 3 , the first filter 51 may include an inductor 50L and a first capacitor 51C. The inductor 50L is connected between the first DC generating unit 32a and the lower electrode of the substrate support 11. The first capacitor 51C is connected between ground and an electrical path 50P connecting the inductor 50L and the lower electrode of the substrate support 11. The first capacitor 51C may be connected between a node 50N and ground. The node 50N is located on the electrical path 50P. The first capacitor 51C may be a fixed capacitor or a variable capacitor. If the first capacitor 51C is a variable capacitor, the waveform of the voltage pulse VP during the first period P1 can be adjusted. The first filter 51 may further include a resistor 51R. The resistor 51R may be connected between the electrical path 50P or the node 50N and the first capacitor 51C.

[0037] In one embodiment, the second filter 52 may include an inductor 50L and a second capacitor 52C. The second filter 52 shares the inductor 50L with the first filter 51. The second capacitor 52C may be connected in parallel with the first capacitor 51C between the electrical path 50P and ground. The second capacitor 52C may be connected in parallel with the first capacitor 51C between the node 50N and ground. The second capacitor 52C may be a fixed capacitor or a variable capacitor. If the second capacitor 52C is a variable capacitor, the waveform of the voltage pulse VP during the second period P2 can be adjusted. The second filter 52 may further include a resistive element 52R. The resistive element 52R may be connected between the electrical path 50P or the node 50N and the second capacitor 52C.

[0038] In one embodiment, the switching circuit 53 may include a first switching element 531 and a second switching element 532. Each of the first switching element 531 and the second switching element 532 may be a power MOSFET. The first switching element 531 is connected between the electrical path 50P or the node 50N and the first capacitor 51C or the resistor element 51R. The second switching element 532 is connected between the electrical path 50P or the node 50N and the second capacitor 52C or the resistor element 52R.

[0039] The first switching element 531 and the second switching element 532 are controlled by the above-mentioned control unit. During the first period P1, the first switching element 531 is controlled to establish a conductive state between the first capacitor 51C and the electrical path 50P. Also, during the first period P1, the second switching element 532 is controlled to establish a non-conductive state between the second capacitor 52C and the electrical path 50P. As a result, during the first period P1, the first filter 51 is connected between the first DC generating unit 32a and the lower electrode of the substrate support unit 11. During the second period P2, the first switching element 531 is controlled to establish a non-conductive state between the first capacitor 51C and the electrical path 50P. Also, during the second period P2, the second switching element 532 is controlled to establish a conductive state between the second capacitor 52C and the electrical path 50P. As a result, during the second period P2, the second filter 52 is connected between the first DC generating unit 32a and the lower electrode of the substrate support unit 11.

[0040] A control method for a plasma processing apparatus according to an exemplary embodiment will be described below with reference to Fig. 6. Fig. 6 is a flowchart of the control method according to an exemplary embodiment. The control method shown in Fig. 6 (hereinafter referred to as "method MT") is applied to a plasma processing apparatus 1. In each step of method MT, each part of the plasma processing apparatus 1 can be controlled by a control unit 2.

[0041] The method MT starts with step STa, in which a substrate W is provided on the substrate support 11. The substrate W is held by an electrostatic chuck 1111.

[0042] Next, a process STb is performed. In the process STb, plasma is generated in the chamber 10. In the process STb, the gas supply unit 20 is controlled to supply gas into the chamber 10, and the exhaust system 40 is controlled to control the pressure in the chamber 10 to a designated pressure. In the process STb, the plasma generating unit 12 generates plasma from the gas in the chamber 10. In one embodiment, a source radio frequency signal (or source radio frequency power) from the first RF generating unit 31a is supplied to generate the plasma.

[0043] Next, a process STc is performed. In the process STc, a voltage pulse VP is periodically applied to the lower electrode of the substrate support 11 to attract ions from the plasma generated in the process STb to the substrate W. In the process STc, the first DC generator 32a, which is a bias power supply, is controlled.

[0044] The process STd is performed during the first period P1. In the process STd, the first filter 51 is connected between the first DC generating unit 32a and the substrate support unit 11. In the process STd, the switching circuit 53 may be controlled as described above.

[0045] The process STe is performed during the second period P2. In the process STe, the second filter 52 is connected between the first DC generating unit 32a and the substrate support unit 11. In the process STe, the switching circuit 53 may be controlled as described above.

[0046] 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.

[0047] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E10] below.

[0048] [E1] A plasma generating unit configured to generate plasma from a gas in the chamber; a bias power supply electrically coupled to the substrate support, the bias power supply configured to periodically apply a voltage pulse to the substrate support to attract ions to a substrate on the substrate support; a first filter having a first cutoff frequency; a second filter having a second cutoff frequency lower than the first cutoff frequency; a switching circuit configured to selectively connect the first filter or the second filter between the bias power supply and the substrate support; and a controller, wherein the voltage pulse falls in a negative direction at its leading edge and rises at its trailing edge, and the controller controls the switching circuit to: connect the first filter between the bias power supply and the substrate support during a first period including the timing of the leading edge of the voltage pulse; and connect the second filter between the bias power supply and the substrate support during a second period including the timing of the trailing edge of the voltage pulse. Plasma processing equipment.

[0049] [E2] The plasma processing apparatus described in E1, wherein the first filter includes: an inductor connected between the bias power supply and the substrate support; and a first capacitor connected between ground and an electrical path connecting the inductor and the substrate support; the second filter includes: the inductor; and a second capacitor arranged between the electrical path and ground; and the switching circuit is connected between the electrical path and the first capacitor and between the electrical path and the second capacitor.

[0050] [E3] The plasma processing apparatus according to E2, wherein the second capacitor is a variable capacitor.

[0051] [E4] The plasma processing apparatus according to any one of E1 to E3, wherein the plasma generating unit includes a high frequency power supply configured to supply source high frequency power to generate the plasma, and the first cutoff frequency and the second cutoff frequency are lower than a frequency of the source high frequency power.

[0052] [E5] The plasma processing apparatus according to any one of E1 to E4, wherein the first cutoff frequency is equal to or greater than 13.56 MHz and equal to or less than 40 MHz.

[0053] [E6] The plasma processing apparatus according to any one of E1 to E5, wherein the second cutoff frequency is equal to or greater than 1 MHz and equal to or less than 10 MHz.

[0054] [E7] A power supply system comprising: a bias power supply electrically coupled to a substrate support in a chamber of a plasma processing apparatus, the bias power supply configured to periodically apply voltage pulses to the substrate support to attract ions from the plasma in the chamber to a substrate on the substrate support; a first filter that is a low pass filter and has a first cutoff frequency; a second filter that is a low pass filter and has a second cutoff frequency lower than the first cutoff frequency; and a switching circuit configured to selectively connect the first filter or the second filter between the bias power supply and the substrate support, wherein the voltage pulse falls in a negative direction at its leading edge and rises at its trailing edge, and the switching circuit is configured to connect the first filter between the bias power supply and the substrate support during a first period that includes the timing of the leading edge of the voltage pulse, and connect the second filter between the bias power supply and the substrate support during a second period that includes the timing of the trailing edge of the voltage pulse.

[0055] [E8] A control method comprising: (a) preparing a substrate on a substrate support in a chamber of a plasma processing apparatus; (b) generating a plasma in the chamber; (c) periodically applying voltage pulses from a bias power supply to the substrate support to attract ions from the plasma to the substrate, the voltage pulses falling negatively at their leading edges and rising positively at their trailing edges; (d) connecting a first filter between the bias power supply and the substrate support during a first time period including the timing of the leading edge of the voltage pulse; and (e) connecting a second filter between the bias power supply and the substrate support during a second time period including the timing of the trailing edge of the voltage pulse, the second filter having a second cutoff frequency lower than the first cutoff frequency of the first filter.

[0056] [E9] The control method according to E8, wherein in (d), a switching circuit is controlled to connect the first filter between the bias power supply and the substrate support, and in (e), the switching circuit is controlled to connect the second filter between the bias power supply and the substrate support.

[0057] [E10] A program for causing a plasma processing apparatus to execute the control method according to E8 or E9.

[0058] 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.

[0059] 1...plasma processing apparatus, 10...chamber, 11...substrate support portion, 12...plasma generating portion, 31a...first RF generating portion, 32a...first DC generating portion, 51...first filter, 52...second filter, 53...switching circuit.

Claims

a plasma generating unit configured to generate plasma from a gas in the chamber; a bias power supply electrically coupled to the substrate support, the bias power supply configured to periodically apply voltage pulses to the substrate support to attract ions to a substrate on the substrate support; a first low-pass filter having a first cutoff frequency; a second low-pass filter having a second cutoff frequency lower than the first cutoff frequency; a switching circuit configured to selectively connect the first filter or the second filter between the bias power supply and the substrate support; and a controller, wherein the voltage pulse falls negatively at its leading edge and rises at its trailing edge, and the controller controls the switching circuit to connect the first filter between the bias power supply and the substrate support during a first period including the timing of the leading edge of the voltage pulse, and to connect the second filter between the bias power supply and the substrate support during a second period including the timing of the trailing edge of the voltage pulse. Plasma processing equipment.

2. The plasma processing apparatus of claim 1, wherein the first filter includes an inductor connected between the bias power supply and the substrate support, and a first capacitor connected between ground and an electrical path connecting the inductor and the substrate support, the second filter includes the inductor and a second capacitor arranged between the electrical path and ground, and the switching circuit is connected between the electrical path and the first capacitor and between the electrical path and the second capacitor.

3. The plasma processing apparatus according to claim 2, wherein the second capacitor is a variable capacitor.

4. The plasma processing apparatus according to any one of claims 1 to 3, wherein the plasma generating unit includes a high frequency power supply configured to supply source high frequency power to generate the plasma, and the first cutoff frequency and the second cutoff frequency are lower than the frequency of the source high frequency power.

5. A plasma processing apparatus according to any one of claims 1 to 3, wherein the first cutoff frequency is 13.56 MHz or more and 40 MHz or less.

6. The plasma processing apparatus according to any one of claims 1 to 3, wherein the second cutoff frequency is 1 MHz or more and 10 MHz or less.

7. A power supply system comprising: a bias power supply electrically coupled to a substrate support in a chamber of a plasma processing apparatus, the bias power supply configured to periodically apply voltage pulses to the substrate support to attract ions from the plasma in the chamber to a substrate on the substrate support; a first filter having a first cutoff frequency; a second filter having a second cutoff frequency lower than the first cutoff frequency; and a switching circuit configured to selectively connect the first filter or the second filter between the bias power supply and the substrate support, wherein the voltage pulse falls negatively at its leading edge and rises at its trailing edge, and the switching circuit is configured to connect the first filter between the bias power supply and the substrate support during a first period that includes the timing of the leading edge of the voltage pulse, and to connect the second filter between the bias power supply and the substrate support during a second period that includes the timing of the trailing edge of the voltage pulse.

8. A control method comprising: (a) providing a substrate on a substrate support in a chamber of a plasma processing apparatus; (b) generating a plasma in the chamber; (c) periodically applying voltage pulses from a bias power supply to the substrate support to attract ions from the plasma to the substrate, the voltage pulses falling negatively at their leading edges and rising positively at their trailing edges; (d) connecting a first filter between the bias power supply and the substrate support during a first time period including the timing of the leading edge of the voltage pulse; and (e) connecting a second filter between the bias power supply and the substrate support during a second time period including the timing of the trailing edge of the voltage pulse, the second filter having a second cutoff frequency lower than the first cutoff frequency of the first filter.

9. The control method of claim 8, wherein in (d), a switching circuit is controlled to connect the first filter between the bias power supply and the substrate support, and in (e), the switching circuit is controlled to connect the second filter between the bias power supply and the substrate support.

10. A program for causing a plasma processing apparatus to execute the control method according to claim 8 or 9.

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