Plasma processing apparatus and plasma processing method

Abstract

To provide a technique for adjusting the distribution of plasma in a plasma processing space.SOLUTION: The disclosed plasma processing apparatus includes a chamber, a substrate support in the chamber, a conductive member, and a variable impedance circuit. The conductive member defines a plasma processing space in the chamber. The variable impedance circuit includes at least one variable impedance element. The at least one variable impedance element is electrically connected between the conductive member and the ground.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Exemplary embodiments of the present disclosure relate to a plasma processing apparatus and a plasma processing method. [Background technology]

[0002] A plasma processing apparatus is used to process a substrate. The plasma processing apparatus includes a chamber and a substrate support. The chamber provides a processing space. The substrate support is disposed within the chamber. In the plasma processing apparatus described in Patent Document 1 listed below, the inner wall of the chamber is covered with a ceramic cylinder. The ceramic cylinder includes a ground electrode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-187881 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for adjusting the distribution of plasma in a plasma processing space. [Means for solving the problem]

[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support within the chamber, a conductive member, and a variable impedance circuit. The conductive member defines a plasma processing volume within the chamber. The variable impedance circuit includes at least one variable impedance element. The at least one variable impedance element is electrically connected between the conductive member and ground. [Effects of the Invention]

[0006] According to one exemplary embodiment, a distribution of plasma in a plasma processing space is adjusted. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a plasma processing system. [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus. [Figure 3] FIG. 3 is a partially enlarged cross-sectional view of a chamber of a plasma processing apparatus according to an exemplary embodiment. [Figure 4] FIG. 4 is a partially enlarged cross-sectional view of a chamber of a plasma processing apparatus according to another exemplary embodiment. [Figure 5] FIG. 5 is a partially enlarged cross-sectional view of a chamber of a plasma processing apparatus according to yet another exemplary embodiment. [Figure 6] FIG. 6 is a partially enlarged cross-sectional view of a chamber of a plasma processing apparatus according to yet another exemplary embodiment. [Figure 7] FIG. 7 is a flow diagram of a plasma processing method according to one exemplary embodiment. DETAILED DESCRIPTION OF THE INVENTION

[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 device 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing device 1 is an example of a substrate processing device. The plasma processing device 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 generating units may be used, including alternating current (AC) plasma generating units and direct current (DC) plasma generating units. In one embodiment, the AC signal (AC power) used in the AC plasma generating unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes a radio frequency (RF) signal and a microwave signal. 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. The program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media 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. Alternatively, 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 processing 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 processing 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 introduction unit 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, and ion components in the formed plasma can be attracted 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 generating unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and 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 generating unit 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 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 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. In one embodiment, a waveform generator for generating a 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 regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0026] Referring now to Figure 3, Figure 3 is a partially enlarged cross-sectional view of a chamber of a plasma processing apparatus according to an exemplary embodiment. As shown in Figure 3, the plasma processing apparatus 1 includes a conductive member 5 and a variable impedance circuit 6. The chamber 10 includes a side wall 10a and an upper wall 10b.

[0027] The conductive member 5 defines a portion of the plasma processing space 10s in the chamber 10. In one embodiment, the conductive member 5 may extend circumferentially around the central axis of the plasma processing space 10s. The conductive member 5 is exposed to the plasma processing space 10s. For example, the conductive member 5 includes an exposed surface exposed to plasma. The conductive member 5 may be electrically isolated from the chamber 10. In one embodiment, the conductive member 5 may be made of silicon.

[0028] In one example, the plasma processing apparatus 1 includes a ceiling 4 located above the plasma processing space 10s. A portion of the ceiling 4 is exposed to the plasma processing space 10s. The ceiling 4 is arranged to define the plasma processing space 10s together with the conductive member 5. The showerhead 13 described above constitutes part of the ceiling 4. As described above, the showerhead 13 includes an upper electrode 14. The upper electrode 14 is arranged above the substrate support 11 and defines the plasma processing space 10s together with the conductive member 5. The plasma generation unit 12 is configured to supply a source RF signal to generate plasma in the plasma processing space 10s.

[0029] The upper electrode 14 includes a top plate 14a and a support 14b (first support). The top plate 14a has a substantially circular plate shape. The top plate 14a is exposed to the plasma processing space 10s. In one example, the top plate 14a is made of silicon, aluminum oxide, or quartz. The top plate 14a may be made of aluminum, and an anticorrosion film may be formed on the surface of the top plate 14a. In one example, the anticorrosion film is made of aluminum oxide or yttrium oxide.

[0030] The support 14b is located above the top plate 14a. The support 14b detachably supports the top plate 14a. In one example, the support 14b is made of aluminum. The at least one gas diffusion chamber 13b is formed in the support 14b. The plurality of gas inlets 13c extend downward from the at least one gas diffusion chamber 13b and communicate with the plasma processing space 10s. The plurality of gas inlets 13c penetrate the support 14b and the top plate 14a.

[0031] The ceiling portion 4 may include a first insulating member 41 and a second insulating member 42. The first insulating member 41 and the second insulating member 42 are each formed from an insulating material such as insulating ceramics, quartz, or metal oxide. The first insulating member 41 is adjacent to the upper electrode 14 and extends in the circumferential direction so as to surround the upper electrode 14. The first insulating member 41 may have a ring shape. The first insulating member 41 is interposed between the upper electrode 14 and the chamber 10. The first insulating member 41 electrically separates the upper electrode 14 from the chamber 10.

[0032] The upper wall 10b is disposed on the side wall 10a. The upper wall 10b is adjacent to the first insulating member 41 and extends in the circumferential direction so as to surround at least a portion of the first insulating member 41. In the example shown in FIG. 3, the upper wall 10b protrudes more inward (toward the upper electrode 14) than the side wall 10a. The side wall 10a may provide a gap between itself and the upper wall 10b. In one example, the side wall 10a provides a gap between itself and the upper wall 10b, the gap opening toward the plasma processing space 10s. The upper end of the side wall 10a may include a portion connected to the upper wall 10b and a portion defining a gap between itself and the upper wall 10b. The portion of the upper end of the side wall 10a that defines a gap between itself and the upper wall 10b is located radially inward of the portion of the upper end of the side wall 10a that is connected to the upper wall 10b. The upper wall 10b may have a ring shape. The top wall 10b and the side wall 10a are electrically connected to each other. The top wall 10b may be electrically connected to the ground G via the side wall 10a. In one example, the side wall 10a and the top wall 10b are each made of aluminum.

[0033] The first insulating member 41 includes a portion 41a (first portion) and a portion 41b (second portion). The portion 41a is located between the upper electrode 14 and the top wall 10b. The portion 41a and the top wall 10b are adjacent to each other in the radial direction. The portion 41b is located below the top wall 10b. At least a portion of the portion 41b may be located in the gap between the side wall 10a and the top wall 10b. The portion 41b protrudes outward (toward the chamber 10) from the portion 41a. The portion 41b may be adjacent to the side wall 10a in the radial direction. The portions 41a and 41b each have an annular shape. In the example shown in FIG. 3, the lower surfaces of the portions 41a and 41b are flush with each other. The portion 41b may have a flange shape located on the edge of the portion 41a.

[0034] The variable impedance circuit 6 includes at least one variable impedance element 60. The at least one variable impedance element 60 includes, for example, a capacitor 61 and / or an inductor 62. In one example, the capacitor 61 is a variable capacitance capacitor. In one example, the inductor 62 is a variable inductor. In the example shown in FIG. 3 , the capacitor 61 and the inductor 62 that constitute the at least one variable impedance element 60 are connected in parallel. The at least one variable impedance element 60 is electrically connected between the conductive member 5 and ground G. The variable impedance circuit 6 is capable of changing the impedance between the conductive member 5 and ground G.

[0035] In the plasma processing apparatus 1, a plasma processing space 10s is defined by a conductive member 5. The density distribution of plasma generated in the plasma processing space 10s varies depending on the potential of the conductive member 5. The conductive member 5 is electrically connected to ground G by at least one variable impedance element 60, and the potential of the conductive member 5 is changed by the impedance of the variable impedance circuit 6. Therefore, in the plasma processing apparatus 1, the potential of the conductive member 5 is changed depending on the impedance between the conductive member 5 and ground G, thereby adjusting the density distribution of plasma generated in the plasma processing space 10s. For example, compared to a configuration in which the conductive member 5 is grounded, in the plasma processing apparatus 1, the density of plasma near the conductive member 5 can be adjusted to be increased. For example, in the plasma processing apparatus 1, the density distribution of plasma may be adjusted to improve the uniformity of plasma processing on the substrate W.

[0036] In one embodiment, the variable impedance circuit 6 may include a switch 63. The switch 63 is configured to selectively connect the conductive member 5 to at least one variable impedance element 60 or ground G. The controller 2 may be configured to control the switch 63. The configuration in which the conductive member 5 is selectively connected to ground G by the switch 63 can be adjusted to reduce the density of plasma generated in the plasma processing space 10s.

[0037] In one embodiment, the control unit 2 may be configured to control the switch 63 to connect the conductive member 5 to ground G during a cleaning process in the chamber 10. During the cleaning process, the plasma density in the plasma processing space 10s is high, and therefore the plasma is likely to leak from the chamber 10. In the plasma processing apparatus 1, connecting the conductive member 5 to ground G during the cleaning process can prevent the plasma from leaking from the chamber 10 during the cleaning process.

[0038] In one embodiment, at least one variable impedance element 60 may have a capacitance of 100 pF or less. The change in impedance between the conductive member 5 and ground G in response to the source RF signal varies more significantly when the capacitance is 100 pF or less than when the capacitance is greater than 100 pF. Therefore, a configuration in which at least one variable impedance element 60 has a capacitance of 100 pF or less can widen the adjustment range of the density distribution of plasma generated in the plasma processing space 10s.

[0039] In one embodiment, the conductive member 5 may be a conductive sidewall 51. The conductive sidewall 51 surrounds the plasma processing space 10s. The conductive sidewall 51 extends circumferentially around the central axis of the plasma processing space 10s. In the example shown in FIG. 3 , the conductive sidewall 51 is disposed adjacent to the sidewall 10a of the chamber 10. The conductive sidewall 51 surrounds the substrate support 11. The sidewall 10a and the conductive sidewall 51 may each have a substantially cylindrical shape. An insulating member (not shown) may be located between the sidewall 10a and the conductive sidewall 51. The conductive sidewall 51 is electrically isolated from the sidewall 10a. The sidewall 10a may be electrically connected to ground G. In the plasma processing apparatus 1, at least one variable impedance element 60 of the variable impedance circuit 6 is electrically connected between the conductive sidewall 51 and ground G. The variable impedance circuit 6 is capable of changing the impedance between the conductive sidewall 51 and ground G.

[0040] Since the conductive side wall 51 is electrically connected to the ground G by at least one variable impedance element 60 of the variable impedance circuit 6, the potential of the conductive side wall 51 is changed by the impedance of the variable impedance circuit 6. Therefore, in the plasma processing apparatus 1, the potential of the conductive side wall 51 is changed according to the impedance of the variable impedance circuit 6, and the density distribution of the plasma generated in the plasma processing space 10s is adjusted in the radial direction.

[0041] In the plasma processing apparatus 1, the switch 63 is configured to selectively connect the conductive side wall 51 to ground G. The switch 63 may be configured to selectively connect the conductive side wall 51 to at least one variable impedance element 60 or ground G. The impedance between the conductive side wall 51 and ground G is adjusted from zero to an impedance that can be changed by the variable impedance circuit 6. Therefore, in the plasma processing apparatus 1, it is possible to widen the adjustment range of the radial density distribution of the plasma generated in the plasma processing space 10s.

[0042] 4, which is a partially enlarged cross-sectional view of a chamber of a plasma processing apparatus according to another exemplary embodiment. As shown in FIG. 4, the plasma processing apparatus 1A includes a conductive member 5A and a variable impedance circuit 6A.

[0043] The conductive member 5A is a conductive ring 52. The conductive ring 52 is disposed above a region between the sidewall 10a and the substrate support 11 of the chamber 10 and above the plasma processing space 10s. The conductive ring 52 may have an annular shape. In one example, the conductive ring 52 surrounds the upper electrode 14. The conductive ring 52 is located below the first insulating member 41. The conductive ring 52 extends radially from below the portion 41a to below the portion 41b. At least a portion of the conductive ring 52 may be located in the gap between the sidewall 10a and the top wall 10b. In the example shown in FIG. 4, the conductive ring 52 protrudes inward (toward the upper electrode 14) beyond the first insulating member 41. The conductive ring 52 is electrically isolated from the upper electrode 14. The conductive ring 52 is electrically isolated from the chamber 10. At least one variable impedance element 60 of the variable impedance circuit 6A is electrically connected between the conductive ring 52 and ground G. The variable impedance circuit 6A is capable of changing the impedance between the conductive ring 52 and the ground G.

[0044] The second insulating member 42 is interposed between the upper electrode 14 and the conductive ring 52. The second insulating member 42 is disposed so as to cover a portion of the conductive ring 52 that protrudes inward beyond the first insulating member 41. In the example shown in FIG. 4, the second insulating member 42 includes a portion 42a (third portion) and a portion 42b (fourth portion). The portion 42a is positioned between the support 14b and the conductive ring 52 in the vertical direction. The portion 42b is positioned between the top plate 14a and the conductive ring 52 in the radial direction. The portion 42a may be positioned between the top plate 14a and the conductive ring 52. The portion 42a protrudes outward (toward the chamber 10) from the portion 42b. The second insulating member 42 has a ring shape. The portions 42a and 42b may each have a ring shape. The portion 42b may have a flange shape disposed on the edge of the portion 42a.

[0045] The plasma processing apparatus 1 further includes a third insulating member 43. The third insulating member 43 is interposed between the conductive ring 52 and the sidewall 10a. The conductive ring 52 is adjacent to the first insulating member 41, the second insulating member 42, and the third insulating member 43. The conductive ring 52 is disposed vertically between the portion 41b of the first insulating member 41 and the third insulating member 43. In the example shown in FIG. 4, the third insulating member 43 includes a support 43a (second support) and a member 43b. The support 43a is disposed on the sidewall 10a. The support 43a may be disposed on the conductive sidewall 51. The support 43a supports the conductive ring 52. The support 43a may be exposed to the plasma processing space 10s. The member 43b is disposed between the support 43a and the conductive ring 52. The member 43b seals the space inside the chamber 10 from the outside. In one example, member 43b is an O-ring.

[0046] Since the conductive ring 52 is electrically connected to the ground G by at least one variable impedance element 60 of the variable impedance circuit 6A, the potential of the conductive ring 52 is changed by the impedance of the variable impedance circuit 6A. Therefore, in the plasma processing apparatus 1A, the potential of the conductive ring 52 is changed according to the impedance of the variable impedance circuit 6A, and the density distribution of the plasma generated in the plasma processing space 10s is adjusted in the vertical direction.

[0047] In the plasma processing apparatus 1A, the switch 63 is configured to selectively connect the conductive ring 52 to at least one variable impedance element 60 or ground G. The impedance between the conductive ring 52 and ground G is adjusted from zero to an impedance that can be changed by the variable impedance circuit 6A. Therefore, in the plasma processing apparatus 1A, the adjustment range of the vertical density distribution of the plasma generated in the plasma processing space 10s can be widened.

[0048] 5, which is a partially enlarged cross-sectional view of a chamber of a plasma processing apparatus according to yet another exemplary embodiment. As shown in FIG. 5, the plasma processing apparatus 1B includes a conductive member 5B and a variable impedance circuit 6B.

[0049] The conductive member 5B is a baffle 53. The baffle 53 extends between the substrate support 11 and the sidewall 10a of the chamber 10. The baffle 53 may extend circumferentially around the central axis of the plasma processing space 10s. The baffle 53 may have an annular shape. The baffle 53 is disposed between the plasma processing space 10s and a space in which the exhaust system 40 is disposed. The baffle 53 has a plurality of through-holes 53a that communicate between the plasma processing space 10s and the space in which the exhaust system 40 is disposed.

[0050] An insulating member (not shown) may be located between the baffle 53 and the side wall 10a. The baffle 53 is electrically isolated from the side wall 10a. An insulating member (not shown) may be located between the baffle 53 and the substrate support 11. The baffle 53 is electrically isolated from the substrate support 11. The baffle 53 and the conductive side wall 51 may be electrically isolated. A gap may be defined between the baffle 53 and the conductive side wall 51. An insulating member (not shown) may be located between the baffle 53 and the conductive side wall 51. At least one variable impedance element 60 of the variable impedance circuit 6B is electrically connected between the baffle 53 and ground G. The variable impedance circuit 6B is capable of changing the impedance between the baffle 53 and ground G.

[0051] Since the baffle 53 is electrically connected to the ground G by at least one variable impedance element 60 of the variable impedance circuit 6B, the potential of the baffle 53 is changed by the impedance of the variable impedance circuit 6B. Therefore, in the plasma processing apparatus 1B, the potential of the baffle 53 is changed according to the impedance of the variable impedance circuit 6B, and the density distribution of the plasma generated in the plasma processing space 10s is adjusted in the vertical direction.

[0052] In the plasma processing apparatus 1B, the switch 63 is configured to selectively connect the baffle 53 to at least one variable impedance element 60 or ground G. The impedance between the baffle 53 and ground G is adjusted from zero to an impedance that can be changed by the variable impedance circuit 6B. Therefore, in the plasma processing apparatus 1B, the adjustment range of the vertical density distribution of the plasma generated in the plasma processing space 10s can be expanded. For example, by causing the return current of the RF signal flowing through the baffle 53 to flow to ground G, leakage of the return current downward in the plasma processing space 10s can be suppressed.

[0053]

[0033] Referring now to Figure 6, which is a partially enlarged cross-sectional view of a chamber of a plasma processing apparatus according to yet another exemplary embodiment, the plasma processing apparatus 1C includes a conductive member 5, a conductive member 5A, a conductive member 5B, a variable impedance circuit 6, a variable impedance circuit 6A, and a variable impedance circuit 6B.

[0054] In one embodiment, the conductive member 5 may be a first conductive member selected from a first group consisting of a conductive sidewall 51, a conductive ring 52, and a baffle 53. In one example, the conductive sidewall 51 is the first conductive member. The variable impedance circuit 6 may be a first variable impedance circuit. The first variable impedance circuit includes at least one first variable impedance element electrically connected between the first conductive member and ground G.

[0055] The plasma processing apparatus 1C may further include a second conductive member different from the first conductive member selected from the first group, and a second variable impedance circuit. In the example shown in FIG. 6, the conductive member 5A is the second conductive member. The conductive ring 52 is the second conductive member. The variable impedance circuit 6A may be a second variable impedance circuit. The second variable impedance circuit includes at least one second variable impedance element electrically connected between the second conductive member and ground G.

[0056] In one embodiment, the plasma processing apparatus 1C may further include a third conductive member and a third variable impedance circuit. The third conductive member is a conductive member separate from the first conductive member and the second conductive member. In the example shown in FIG. 6, the conductive member 5B is the third conductive member. The baffle 53 is the third conductive member. The variable impedance circuit 6B may be a third variable impedance circuit. The third variable impedance circuit includes at least one third variable impedance element electrically connected between the third conductive member and ground G. In one embodiment, two or more of the first conductive member, the second conductive member, and the third conductive member may be made of silicon. The conductive members 5, 5A, and 5B may each be made of silicon. That is, the conductive sidewall 51, the conductive ring 52, and the baffle 53 may each be made of silicon.

[0057] At least one variable impedance element 60 (at least one first variable impedance element) of the variable impedance circuit 6 is electrically connected between the conductive side wall 51 and ground G. The variable impedance circuit 6 is capable of changing the impedance between the conductive side wall 51 and ground G. At least one variable impedance element 60 (at least one second variable impedance element) of the variable impedance circuit 6A is electrically connected to the conductive ring 52. The variable impedance circuit 6A is capable of changing the impedance between the conductive ring 52 and ground G. At least one variable impedance element 60 (at least one third variable impedance element) of the variable impedance circuit 6B is electrically connected between the baffle 53 and ground G. The variable impedance circuit 6B is capable of changing the impedance between the baffle 53 and ground G.

[0058] As described above, the plasma processing apparatus 1 may include the first DC generator 32a and / or the second RF generator 31b. The first DC generator 32a and / or the second RF generator 31b are examples of bias power supplies. The bias power supplies are configured to supply an electric bias to attract ions from the plasma in the plasma processing space 10s to the substrate W on the substrate support 11. The first DC signal from the first DC generator 32a and / or the bias RF signal from the second RF generator 31b are examples of an electric bias. The bias generators are electrically connected to the substrate support 11.

[0059] In one embodiment, the first DC generator 32a is configured to supply a sequence of voltage pulses as the electric bias to the substrate support 11. The thinner the plasma sheath, the larger the current flowing from the plasma to ground G via the conductive member 5 and the variable impedance circuit 6. The plasma sheath is a boundary region of the plasma generated along the conductive member 5 that defines the plasma processing space 10s. The larger the current flowing through the conductive member 5 and the variable impedance circuit 6, the greater the effect of the variable impedance circuit 6 on the plasma density distribution. Therefore, in the plasma processing apparatus 1, the adjustment range of the plasma density distribution generated in the plasma processing space 10s can be widened. When a sequence of voltage pulses is supplied as the electric bias, the plasma sheath becomes relatively thin. Therefore, the configuration in which the first DC generator 32a supplies a sequence of voltage pulses as the electric bias can widen the adjustment range of the plasma density distribution generated in the plasma processing space 10s. In one embodiment, the second RF generator 31b may be configured to supply a bias RF signal as the electric bias.

[0060] A substrate processing method according to one exemplary embodiment will be described below with reference to FIG. 7. FIG. 7 is a flowchart of a plasma processing method according to one exemplary embodiment. The plasma processing method shown in FIG. 7 (hereinafter referred to as "method MT") may be performed by any of the plasma processing apparatuses 1, 1A, 1B, and 1C shown in FIGS. 3 to 6. In the following, an example will be described in which the control unit 2 or an operator controls each part of the plasma processing apparatus to perform the plasma processing method.

[0061] The method MT includes steps STa, STb, and STc. In one embodiment, the method MT may include steps STd and STe. Step STa is performed first. In step STa, a substrate W is prepared on a substrate support 11 in a chamber 10 of the plasma processing apparatus 1.

[0062] In step STb, at least one variable impedance element 60 of the variable impedance circuit 6 is electrically connected between the conductive member 5 defining the plasma processing space 10s in the chamber 10 and the ground G. In one embodiment, the conductive member 5 in step STb may extend circumferentially around the central axis of the plasma processing space 10s. In step STc, plasma processing is performed on the substrate W on the substrate support 11 by generating plasma in the plasma processing space 10s. For example, in step STc, after a processing gas is introduced into the chamber 10 from the showerhead 13, a source RF signal is supplied from the plasma generating unit 12 to generate plasma in the plasma processing space 10s. In step STc, an electric bias may be supplied from a bias power supply to attract ions from the plasma in the plasma processing space 10s to the substrate W on the substrate support 11. Note that step STb may be performed during or before step STc.

[0063] In step STd, the conductive member 5 is electrically grounded. In step STd, the switch 63 may be controlled to connect the conductive member 5 to the ground G in order to ground the conductive member 5. In step STe, the inside of the chamber 10 is cleaned. In the cleaning process, a relatively high-density plasma is generated in the plasma processing space 10s to remove deposits adhering to the inside of the chamber 10. Note that step STc may be performed during the period in which step STe is being performed or before step STe is performed.

[0064] 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.

[0065] In the method MT, steps STa, STb, and STc may not be performed, and steps STd and STe may be performed independently. In this case, in the method MT, only the cleaning process inside the chamber 10 is performed. The switch 63 may electrically connect the conductive member 5 to both at least one variable impedance element 60 and ground G. In this case, it is difficult for a current to flow through the at least one variable impedance element 60, and as a result, the conductive member 5 and ground G are electrically connected.

[0066] Various exemplary embodiments included in the present disclosure are now described in [E1] to [E17] below.

[0067] [E1] a chamber; a substrate support within the chamber; an electrically conductive member defining a portion of a plasma processing volume within the chamber; a variable impedance circuit including at least one variable impedance element electrically connected between the conductive member and ground; A plasma processing apparatus comprising: [E2] the variable impedance circuit includes a switch configured to selectively connect the conductive member to the at least one variable impedance element or the ground; The plasma processing apparatus further includes a control unit configured to control the switch. The plasma processing apparatus according to E1. [E3] the control unit is configured to control the switch to connect the conductive member to the ground during a cleaning process in the chamber. The plasma processing apparatus according to E2. [E4] The plasma processing apparatus according to any one of E1 to E3, wherein the conductive member extends in a circumferential direction around a central axis of the plasma processing space. [E5] the conductive member is a conductive sidewall surrounding the plasma processing space; The plasma processing apparatus according to any one of E1 to E4. [E6] the conductive member is a conductive ring disposed above the region between the substrate support and the sidewall of the chamber and above the plasma processing space; The plasma processing apparatus according to any one of E1 to E4. [E7] the conductive member is a baffle extending between the substrate support and a sidewall of the chamber; The plasma processing apparatus according to any one of E1 to E4. [E8] The plasma processing apparatus according to any one of E1 to E7, wherein the conductive member is made of silicon. [E9] The conductive member is a conductive sidewall extending circumferentially around a central axis of the plasma processing space and surrounding the plasma processing space; a conductive ring extending circumferentially around a central axis of the plasma processing space and positioned above the plasma processing space and above a region between the substrate support and a sidewall of the chamber; and a baffle extending between the substrate support and the sidewall of the chamber; a first conductive member selected from a first group consisting of: the variable impedance circuit is a first variable impedance circuit including at least one first variable impedance element electrically connected between the first conductive member and the ground, The plasma processing apparatus comprises: a second conductive member selected from the first group and separate from the first conductive member; a second variable impedance circuit including at least one second variable impedance element electrically connected between the second conductive member and the ground; Further comprising: The plasma processing apparatus according to any one of E1 to E4. [E10] a third conductive member selected from the first group and separate from the first conductive member and the second conductive member; a third variable impedance circuit including at least one third variable impedance element electrically connected between the third conductive member and the ground; The plasma processing apparatus according to E9, further comprising: [E11] The plasma processing apparatus according to E10, wherein two or more of the first conductive member, the second conductive member, and the third conductive member are formed from silicon. [E12] the at least one variable impedance element has a capacitance of 100 pF or less; The plasma processing apparatus according to any one of E1 to E11. [E13] an upper electrode disposed above the substrate support and defining the plasma processing space together with the conductive member; a plasma generating unit configured to supply an RF signal to the upper electrode or the substrate support to generate plasma in the plasma processing space; Further comprising: The plasma processing apparatus according to any one of E1 to E12. [E14] a bias power supply configured to provide an electrical bias to the substrate support to attract ions from the plasma in the plasma processing space to a substrate on the substrate support; the bias power supply includes a voltage pulse generator configured to supply a sequence of voltage pulses as the electrical bias to the substrate support; The plasma processing apparatus according to any one of E1 to E13. [E15] the bias power supply further includes an RF generator configured to provide a bias RF signal as the electrical bias to the substrate support. The plasma processing apparatus according to E14. [E16] (a) providing a substrate on a substrate support within a chamber; (b) electrically connecting at least one variable impedance element of a variable impedance circuit between a conductive member defining a portion of a plasma processing volume within the chamber and ground; (c) performing plasma processing on the substrate on the substrate support by generating plasma in the plasma processing space; A plasma processing method comprising: [E17] (d) electrically grounding the conductive member; (e) cleaning the inside of the chamber; The plasma processing method according to E16, further comprising: [E18] In the case of (b), the conductive member extends in a circumferential direction around a central axis of the plasma processing space. The plasma treatment method according to E16 or 17.

[0068] The plasma processing methods described in E16 to E18 may be performed in the plasma processing apparatus described in any one of E1 to E15.

[0069] 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. [Explanation of symbols]

[0070] 1...plasma processing apparatus, 2...controller, 5, 5A, 5B...conductive member, 6, 6A, 6B...variable impedance circuit, 63...switch, 10...chamber, 10a...side wall, 10s...plasma processing space, 11...substrate support, 12...plasma generation unit, 14...upper electrode, 31b...RF generation unit, 51...conductive side wall, 52...conductive ring, 53...baffle, G...ground, W...substrate

Claims

1. a chamber; a substrate support within the chamber; an electrically conductive member defining a portion of a plasma processing volume within the chamber; a variable impedance circuit including at least one variable impedance element electrically connected between the conductive member and ground; A plasma processing apparatus comprising:

2. the variable impedance circuit includes a switch configured to selectively connect the conductive member to the at least one variable impedance element or the ground; The plasma processing apparatus further includes a control unit configured to control the switch. The plasma processing apparatus according to claim 1 .

3. the control unit is configured to control the switch to connect the conductive member to the ground during a cleaning process in the chamber. The plasma processing apparatus according to claim 2 .

4. The plasma processing apparatus according to claim 1 , wherein the conductive member extends in a circumferential direction around a central axis of the plasma processing space.

5. the conductive member is a conductive sidewall surrounding the plasma processing space; The plasma processing apparatus according to claim 4 .

6. the conductive member is a conductive ring disposed above the region between the substrate support and the sidewall of the chamber and above the plasma processing space; The plasma processing apparatus according to claim 4 .

7. the conductive member is a baffle extending between the substrate support and a sidewall of the chamber; The plasma processing apparatus according to claim 4 .

8. The plasma processing apparatus according to claim 1 , wherein the conductive member is made of silicon.

9. The conductive member is a conductive sidewall extending circumferentially around a central axis of the plasma processing space and surrounding the plasma processing space; a conductive ring extending circumferentially around a central axis of the plasma processing space and positioned above the plasma processing space and above a region between the substrate support and a sidewall of the chamber; and a baffle extending between the substrate support and the sidewall of the chamber; a first conductive member selected from a first group consisting of: the variable impedance circuit is a first variable impedance circuit including at least one first variable impedance element electrically connected between the first conductive member and the ground, The plasma processing apparatus comprises: a second conductive member selected from the first group and separate from the first conductive member; a second variable impedance circuit including at least one second variable impedance element electrically connected between the second conductive member and the ground; Further comprising: The plasma processing apparatus according to any one of claims 1 to 4.

10. a third conductive member selected from the first group and separate from the first conductive member and the second conductive member; a third variable impedance circuit including at least one third variable impedance element electrically connected between the third conductive member and the ground; The plasma processing apparatus of claim 9 , further comprising:

11. The plasma processing apparatus of claim 10 , wherein at least two of the first conductive member, the second conductive member, and the third conductive member are made of silicon.

12. the at least one variable impedance element has a capacitance of 100 pF or less; The plasma processing apparatus according to any one of claims 1 to 8.

13. an upper electrode disposed above the substrate support and defining the plasma processing space together with the conductive member; a plasma generating unit configured to supply an RF signal to the upper electrode or the substrate support to generate plasma in the plasma processing space; Further comprising: The plasma processing apparatus according to any one of claims 1 to 8.

14. a bias power supply configured to provide an electrical bias to the substrate support to attract ions from the plasma in the plasma processing space to a substrate on the substrate support; the bias power supply includes a voltage pulse generator configured to supply a sequence of voltage pulses as the electrical bias to the substrate support; The plasma processing apparatus according to any one of claims 1 to 8.

15. the bias power supply further includes an RF generator configured to provide a bias RF signal as the electrical bias to the substrate support; The plasma processing apparatus according to claim 14 .

16. (a) providing a substrate on a substrate support within a chamber; (b) electrically connecting at least one variable impedance element of a variable impedance circuit between a conductive member defining a portion of a plasma processing volume within the chamber and ground; (c) performing plasma processing on the substrate on the substrate support by generating plasma in the plasma processing space; A plasma processing method comprising:

17. (d) electrically grounding the conductive member; (e) cleaning the inside of the chamber; The plasma processing method of claim 16 , further comprising:

18. In the case of (b), the conductive member extends in a circumferential direction around a central axis of the plasma processing space. The plasma processing method according to claim 16 or 17.

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