Plasma processing apparatus and electric potential control method

Abstract

This plasma processing apparatus comprises a chamber, a stage, a plurality of electrodes, an electric power supply, a switch unit, and a control unit. The chamber is configured to be capable of generating plasma therein. The stage is disposed in the chamber, is formed of a dielectric, allows a substrate to be placed thereon, and is configured such that a ring assembly can be placed around the substrate. The plurality of electrodes are provided in a portion that faces the ring assembly inside the stage. The electric power supply is configured to be capable of supplying bias electric power for drawing charged particles in the plasma. The switch unit is configured to be able to individually supply the bias electric power that is supplied from the electric power source to the plurality of electrodes. The control unit controls the switch unit.

Description

Plasma processing apparatus and potential control method

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

[0002] Japanese Patent Laid-Open No. 2006-121299 discloses a plasma processing apparatus that generates plasma on a substrate to perform a predetermined process, comprising: a susceptor having a substrate mounting portion for mounting the substrate and to which high-frequency power is applied; a focus ring integrally formed of an outer ring disposed to surround the periphery of the substrate mounted on the substrate mounting portion and having an upper surface higher than the substrate; an inner ring disposed inside the outer ring and below the peripheral edge of the substrate and having an upper surface lower than the substrate; a dielectric ring interposed between the focus ring and the susceptor; a dielectric constant varying mechanism that varies the dielectric constant of the dielectric ring; and a controller that controls the top surface potential of the focus ring by driving the dielectric constant varying mechanism to adjust the dielectric constant of the dielectric ring.

[0003] JP 2012-064671 A

[0004] The present disclosure provides a technique that makes it possible to control the potential of a ring assembly without providing an elevator mechanism.

[0005] A plasma processing apparatus according to one aspect of the present disclosure includes a chamber, a stage, multiple electrodes, a power supply, a switch unit, and a control unit. The chamber is configured to be capable of generating plasma therein. The stage is disposed within the chamber and is formed of a dielectric material, and is configured to support a substrate and to support a ring assembly around the substrate. The multiple electrodes are provided inside the stage in a portion facing the ring assembly. The power supply is configured to be capable of supplying bias power for attracting charged particles in the plasma. The switch unit is configured to be capable of individually supplying bias power supplied from the power supply to the multiple electrodes. The control unit controls the switch unit.

[0006] According to the present disclosure, the potential of the ring assembly can be controlled without providing a lifting mechanism.

[0007] FIG. 1 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus. FIG. 2A is a cross-sectional view showing an example of the configuration of a main body of a substrate support. FIG. 2B is an enlarged view of multiple electrodes of an electrostatic chuck. FIG. 3A is a cross-sectional view showing another example of the configuration of the main body of a substrate support. FIG. 3B is an enlarged view of multiple electrodes of an electrostatic chuck. FIG. 4 is a circuit diagram schematically illustrating an example of the configuration of a plasma processing apparatus 1. FIG. 5 is a diagram illustrating a model used in a simulation. FIG. 6 is a diagram illustrating simulation results. FIG. 7 is a diagram illustrating changes in processing characteristics of plasma processing. FIG. 8 is a flowchart illustrating an example of the process flow of a potential control method. FIG. 9A is a diagram illustrating another example of an electrode arrangement. FIG. 9B is a diagram illustrating an example of a combination of on and off switches. FIG. 10A is a diagram illustrating an example in which the annular region of an electrostatic chuck is divided into multiple zones. FIG. 10B is a cross-sectional view showing an example of the configuration of a main body when multiple electrodes are provided for each zone.

[0008] Hereinafter, embodiments of a plasma processing apparatus and a potential control method will be described in detail with reference to the drawings. Note that the plasma processing apparatus and the potential control method disclosed below are not limited to the following embodiments.

[0009] Conventionally, plasma processing apparatuses have been known that perform plasma processing, such as plasma etching, on substrates such as semiconductor wafers (hereinafter also referred to as "wafers"). In plasma processing apparatuses, a ring assembly, such as a focus ring, is disposed around the substrate to achieve uniform plasma distribution. In plasma processing apparatuses, changes in the height of the boundary surface between the bulk plasma and the sheath (hereinafter referred to as the "sheath surface") due to factors such as wear on the top surface of the ring assembly caused by plasma etching or changes in the potential of the ring assembly can affect the processing results for the substrate. For example, if the sheath surface heights differ between the substrate and the top of the ring assembly, the electric field around the substrate is not perpendicular to the substrate. This causes the trajectories of charged particles, such as ions, in the plasma to tilt, resulting in a phenomenon known as tilting, in which holes are formed at an angle.

[0010] Therefore, a method has been proposed in which a dielectric ring is placed on the underside of the ring assembly and the dielectric ring is raised and lowered to adjust the dielectric constant of the ring assembly and control the potential of the ring assembly to a desired value.

[0011] However, conventional methods require a lifting mechanism to raise and lower the dielectric ring, which can generate particles. Therefore, a technology that can control the potential of the ring assembly without using a lifting mechanism is desired.

[0012] (Embodiment) [Device Configuration]

[0013] An example of a plasma processing apparatus according to the present disclosure will be described below. In the embodiment described below, a plasma processing apparatus according to the present disclosure will be described as an example of a plasma processing system having a system configuration.

[0014] An example of the configuration of a plasma processing system will be described below: Fig. 1 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus.

[0015] The plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a controller 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0016] 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.

[0017] 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 is formed of a dielectric material. For example, the electrostatic chuck 1111 is formed of a ceramic material. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The electrostatic chuck 1111 is configured to allow a substrate W to be placed thereon and a ring assembly 112 to be placed around the substrate W. For example, the ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have the annular region 111b. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF (Radio Frequency) power supply 31 and / or a DC (Direct Current) power supply 32 (described later) may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal (described later) is supplied to the at least one RF / DC electrode, the RF / DC electrode is also referred to as 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. In this embodiment, the electrostatic chuck 1111 corresponds to the stage of the present disclosure.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include one or more flow modulation devices to modulate or pulse the flow rate of the at least one process gas.

[0022] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates a plasma from at least one process gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more process gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0023] 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.

[0024] 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. For example, the frequency of the bias RF signal is 400 kHz. 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. In the embodiments, the power supply 30 or the second RF generator 31b corresponds to the power supply of the present disclosure.

[0025] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the at least one lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to the at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0026] In various embodiments, at least one of the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0027] 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.

[0028] 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).

[0029] Next, an example of the configuration of the substrate support unit 11 will be described. Note that, hereinafter, the components related to the path through which the bias RF signal flows will be mainly described. Fig. 2A is a cross-sectional view showing an example of the configuration of the main body 111 of the substrate support unit 11. Fig. 2A schematically shows a cross section of the main body 111. The main body 111 has an electrostatic chuck 1111 provided on a base 1110.

[0030] The base 1110 is made of aluminum and functions as a lower electrode. The second RF generator 31b is connected to the base 1110 via wiring 34. An impedance matching circuit 35 is provided on the wiring 34. The impedance matching circuit 35 matches the impedance on the second RF generator 31b side with the impedance on the load side, such as the base 1110 and the plasma processing chamber 10.

[0031] A substrate W is placed on the central region 111a of the electrostatic chuck 1111. A ring assembly 112 is placed on the annular region 111b of the electrostatic chuck 1111. The electrostatic chuck 1111 has an electrostatic electrode 1111b in a portion of the ceramic member 1111a facing the substrate W. The electrostatic chuck 1111 has a plurality of electrodes 50 in a portion of the ceramic member 1111a facing the ring assembly 112. The plurality of electrodes 50 are each formed in an annular shape corresponding to the annular region 111b. The plurality of electrodes 50 differ in at least one of their depths from the annular region 111b and the area of ​​their surfaces facing the ring assembly 112 so that the electrostatic capacitances between the electrodes 50 and the ring assembly 112 differ from one another. That is, the plurality of electrodes 50 differ in at least one of their distances from the ring assembly 112 and the area of ​​their surfaces facing the ring assembly 112. The plurality of electrodes 50 are arranged so as not to overlap. 2B is an enlarged view of the multiple electrodes 50 of the electrostatic chuck 1111. In FIGS. 2A and 2B, three electrodes 50a-50c are provided in a portion of the ceramic member 1111a facing the ring assembly 112. The electrodes 50a-50c are provided at different depths from the annular region 111b. The capacitance between the electrodes 50a-50c and the ring assembly 112 is a capacitance C L1 -C L3 The electrodes 50a-50c have a capacitance C between them and the ring assembly 112. L1 -C L3If the electrodes 50a-50c are different, they may be formed with the same area or different areas. In Figures 2A and 2B, the electrodes 50a-50c are formed with the same area and are arranged in the order of electrodes 50a-50c from the annular region 111b. The distance from the ring assembly 112 is the largest for electrode 50a and the smallest for electrode 50c, and the size of electrode 50b is between the size of electrodes 50a and 50c. Therefore, the capacitance C L1 -C L3 is C L1 >C L2 >C L3 The order of increasing distance from the ring assembly 112 is not limited to the order of the electrodes 50a-50c. For example, the distance between the electrodes 50a-50c and the ring assembly 112 may be increased in the order of the electrodes 50a-50c, or may be increased in the order of the electrodes 50a, 50c, and 50b. In other words, the order of increasing distance between the electrodes 50a, 50c, and 50b and the ring assembly 112 may be reversed as desired.

[0032] The electrostatic electrode 1111b is connected to the base 1110 via a wire 36. The three electrodes 50a-50c are connected to a switch mechanism 38 via wires 37a-37c, respectively. The switch mechanism 38 is connected to the base 1110 via a wire 39.

[0033] The second RF generating unit 31b supplies a bias RF signal to the base 1110 via the wiring 34. The impedance matching circuit 35 matches the impedance on the second RF generating unit 31b side with the impedance on the load side. By performing matching using the impedance matching circuit 35, it is possible to suppress power loss due to reflection of the bias RF signal, heat generation in the impedance matching circuit 35, and the like.

[0034] The bias RF signal supplied to the base 1110 is supplied to the electrostatic electrode 1111b via wiring 36 and to the switch mechanism 38 via wiring 39. The switch mechanism 38 is configured to be able to individually supply the bias RF signal supplied from the second RF generation unit 31b to the electrodes 50a-50c via wiring 37a-37c. For example, the switch mechanism 38 is configured to incorporate switches individually connected to the wiring 37a-37c, and to individually supply the bias RF signal to the electrodes 50a-50c via the wiring 37a-37c by switching each switch on and off. When turning an RF signal such as a bias RF signal on and off, for example, a bidirectional switch can be used as the switch. In the embodiment, the switch mechanism 38 corresponds to the switch unit of the present disclosure.

[0035] The control unit 2 is connected to the switch mechanism 38. The control unit 2 controls the switch mechanism 38. For example, the control unit 2 outputs a signal that controls the On / Off of each switch of the switch mechanism 38.

[0036] 2A and 2B, the case where the plurality of electrodes 50 (electrodes 50a-50c) are arranged at different depths from the annular region 111b has been described. However, the arrangement of the plurality of electrodes 50 is not limited to this. Another example of the configuration of the substrate support portion 11 will be described. FIG. 3A is a cross-sectional view showing another example of the configuration of the main body portion 111 of the substrate support portion 11. FIG. 3B is an enlarged view of the portion of the electrostatic chuck 1111 where the plurality of electrodes 50 are arranged. In the configuration shown in FIGS. 3A and 3B, three electrodes 50a-50c are provided in a portion facing the ring assembly 112 inside the ceramic member 1111a. The electrodes 50a-50c are formed so that the area of ​​the surface facing the ring assembly 112 increases in the order of the electrodes 50a-50c, and are provided at the same depth from the annular region 111b. The electrostatic capacitance between the electrodes 50a-50c and the ring assembly 112 is C L1 -C L3 The electrodes 50a to 50c are formed in the order of increasing surface area facing the ring assembly 112, and therefore the capacitance C L1 -C L3 is C L1 >C L2 >CL3 The order of increasing area of ​​the surfaces of the electrodes 50a-50c facing the ring assembly 112 is not limited to the order of the electrodes 50a-50c. For example, the surfaces of the electrodes 50a-50c facing the ring assembly 112 may be formed so that the areas become smaller in the order of the electrodes 50a-50c, or may be formed so that the areas become smaller in the order of the electrodes 50a, 50c, and 50b. In other words, the order of increasing area of ​​the surfaces of the electrodes 50a-50c facing the ring assembly 112 may be arbitrarily reversed.

[0037] Fig. 4 is a circuit diagram schematically illustrating an example of the configuration of the plasma processing apparatus 1. Fig. 4 shows an equivalent circuit of the plasma processing apparatus 1, which shows the electrical characteristics of a path through which a bias RF signal flows.

[0038] The bias RF signal flows from the second RF generating unit 31b to the wiring 34. An impedance matching circuit 35 provided on the wiring 34 matches the impedance between the second RF generating unit 31b side and the load side. The wiring 34 branches into a path 60a and a path 60b. The path 60a shows the electrical characteristics of the central region 111a of the base 1110. The path 60b shows the electrical characteristics of the annular region 111b of the base 1110.

[0039] Capacitance C of path 60a stage indicates the capacitance between the central region 111a of the base 1110 and the substrate W. The resistor 61a and capacitor 61b of the path 60a indicate the electrical characteristics of the plasma in the central region 111a.

[0040] Capacitance C of path 60b L1 -C L3 indicates the capacitance between the electrodes 50a-50c of the annular region 111b and the ring assembly 112. The capacitance C of the path 60b base indicates the capacitance between the annular region 111b of the base 1110 and the ring assembly 112. Switches SW1-SW3 indicate the switches of the switch mechanism 38 connected to the electrodes 50a-50c, respectively. The resistor 62a and capacitor 62b of the path 60b indicate the electrical characteristics of the plasma in the annular region 111b.

[0041] In the path 60b, the capacitance C base and capacitance C connected in parallel L1 -C L3 The capacitance of the ring assembly 112 is changed as a whole.

[0042] Here, an example of the results of simulating the change in the potential of the ring assembly 112 will be described. FIG. 5 is a diagram illustrating a model used in the simulation. FIG. 5 shows a model 80 simulating the electrostatic chuck 1111, the base 1110, the ring assembly 112, and the substrate W. The model 80 includes a line 81 simulating the electrostatic electrode 1111b, lines 82a-82c simulating the electrodes 50a-50c, and a line 83 simulating the base 1110. The line 82a is located 0.35 mm from a surface 86 corresponding to the annular region 111b of the electrostatic chuck 1111. The line 82b is located 1.75 mm from the surface 86. The line 82c is located 3.15 mm from the surface 86. The line 83 is located 4.5 mm below the surface 86. The lines 81 and 83 are connected by a line 84. Lines 82a-82c and line 83 are connected by line 85. In FIG. 5, the simulated cases are indicated as "BASE," "BTM," "MID," and "TOP." In each of the cases of BASE, BTM, MID, and TOP, lines 81-85 indicate the portions through which the bias RF signal is flowing with solid lines, and the cases in which the bias RF signal is not flowing with dashed lines. For example, in the case of BASE, lines 81, 83, and 84 are indicated with solid lines, and lines 82a-82c and 85 are indicated with wavy lines. Therefore, in the case of BASE, a bias RF signal flows to the electrostatic electrode 1111b and the base 1110, but a bias RF signal does not flow to the electrodes 50a-50c. In the case of TOP, lines 81, 82a, 83, 84, and 85 are indicated with solid lines, and lines 82b and 82c are indicated with wavy lines. Therefore, TOP indicates a case where a bias RF signal flows through the electrostatic electrode 1111b, the electrode 50a, and the base 1110, but no bias RF signal flows through the electrodes 50b and 50c.

[0043] BASE corresponds to the case where switches SW1-SW3 are all off in the equivalent circuit shown in Fig. 4. BTM corresponds to the case where switch SW3 is on and switches SW1 and SW2 are off in the equivalent circuit shown in Fig. 4. MID corresponds to the case where switch SW2 is on and switches SW1 and SW3 are off in the equivalent circuit shown in Fig. 4. TOP corresponds to the case where switch SW1 is on and switches SW2 and SW3 are off in the equivalent circuit shown in Fig. 4.

[0044] 6 is a diagram illustrating the simulation results. Fig. 6 shows the voltage (substrate voltage) at the substrate W portion of the model 80 and the voltage (FR voltage) at the ring assembly 112 portion when simulating the cases of BASE, BTM, MID, and TOP. In Fig. 6, the substrate voltage and FR voltage represent negative peak voltages generated by the bias RF signal. The voltage (substrate voltage) at the substrate W portion changes little at BASE, BTM, MID, and TOP, with a change of 0.4%. On the other hand, the voltage (FR voltage) at the ring assembly 112 portion changes much at BASE, BTM, MID, and TOP, with a change of 3.2%.

[0045] In the conventional method, a dielectric ring is placed on the underside of the ring assembly 112 and the potential of the ring assembly 112 is controlled by raising and lowering the dielectric ring. However, the conventional method requires a lifting mechanism for raising and lowering the dielectric ring, which may generate particles. Furthermore, as described above, the frequency of the bias RF signal is in the range of 100 kHz to 60 MHz. The conventional method is less effective in controlling the potential of the ring assembly 112 as the frequency of the bias RF signal decreases. For example, if the frequency of the bias RF signal is 400 kHz, the conventional method cannot sufficiently change the potential of the ring assembly 112.

[0046] In contrast, in the plasma processing apparatus 1, the control unit 2 controls the switch mechanism 38 to change the electrodes 50a-50c through which the bias RF signal is applied, thereby changing the potential of the ring assembly 112 without providing a lifting mechanism. Furthermore, even when the bias RF signal is of a low frequency, the plasma processing apparatus 1 can sufficiently change the potential of the ring assembly 112 by having the control unit 2 control the switch mechanism 38 to change the electrodes 50a-50c through which the bias RF signal is applied.

[0047] By changing the potential of the ring assembly 112 in this manner, the plasma processing apparatus 1 can control the height of the plasma sheath surface around the periphery of the substrate W. This allows the plasma processing apparatus 1 to change the processing characteristics of the plasma processing around the periphery of the substrate W. For example, when performing plasma etching as the plasma processing, the plasma processing apparatus 1 can change the angle of the hole around the periphery of the substrate W.

[0048] 7 is a diagram illustrating changes in processing characteristics of plasma processing. Fig. 7 shows the angle of holes in the peripheral portion (140-150 mm) of a substrate W when plasma etching is performed on a substrate W with a radius of 150 mm in each of the cases of BASE, BTM, MID, and TOP. For example, even if the angle of the holes in the peripheral portion of the substrate W is nearly perpendicular (90 degrees) in BASE, the angle of the holes in the peripheral portion of the substrate W can be controlled by using BTM, MID, or TOP.

[0049] The controller 2 controls the processing characteristics of the plasma processing around the periphery of the substrate W by controlling the switch mechanism 38 to change the potential of the ring assembly 112. For example, in the plasma processing apparatus 1, when the upper surface of the ring assembly 112 is worn away by plasma etching, the plasma sheath surface around the periphery of the substrate W drops, causing tilting around the periphery of the substrate W. Therefore, the controller 2 controls the switch mechanism 38 to supply a bias RF signal to the electrode with a large capacitance with the ring assembly 112 in accordance with the wear of the ring assembly 112. In the plasma processing apparatus 1, tilting of holes formed in the substrate W gradually increases as the substrate W is repeatedly subjected to plasma processing and cleaning, exceeding an allowable range. For example, the controller 2 adjusts the potential of the ring assembly 112 when the tilting reaches a predetermined threshold value while remaining within an allowable range. For example, the controller 2 controls the switch mechanism 38 to supply a bias RF signal to the electrode with a large capacitance with the ring assembly 112 each time a predetermined number of substrates W are plasma etched, at which point tilting exceeds the allowable range. For example, when a bias RF signal is supplied to the electrode 50c during plasma etching, the control unit 2 controls the switch mechanism 38 to supply a bias RF signal to the electrode 50b or the electrode 50b. This makes it possible to raise the plasma sheath surface around the periphery of the substrate W, thereby suppressing tilting around the periphery of the substrate W.

[0050] The control unit 2 may control the switch mechanism 38 to change the potential of the ring assembly 112 depending on the plasma processing to be performed. For example, when process A and process B are performed as plasma processing, the control unit 2 may control the switch mechanism 38 to change the potential of the ring assembly 112 between process A and process B. The control unit 2 may also control the switch mechanism 38 to change the potential of the ring assembly 112 during plasma processing. When increasing the potential of the ring assembly 112, the control unit 2 controls the switch mechanism 38 to supply a bias RF signal to an electrode having a large capacitance with the ring assembly 112. When decreasing the potential of the ring assembly 112, the control unit 2 controls the switch mechanism 38 to supply a bias RF signal to an electrode having a small capacitance with the ring assembly 112. In this way, the plasma processing apparatus 1 can change the potential of the ring assembly 112 depending on the plasma processing to be performed.

[0051] [Potential Control Method]

[0052] 8 is a flowchart showing an example of the process flow of the potential control method. The process illustrated in FIG. 8 is realized by the processing unit 2a1 of the control unit 2 reading a program from the storage unit 2a2 and executing the read program when changing the potential of the ring assembly 112. For example, the control unit 2 executes the process when the potential of the ring assembly 112 is to be significantly changed each time a predetermined number of substrates W are plasma etched, at which point tilting exceeds the tolerable range. The processing unit 2a1 also executes the process when the potential of the ring assembly 112 is to be increased or decreased depending on the plasma process to be performed.

[0053] The processing unit 2a1 determines whether to significantly change the potential of the ring assembly 112 (S10). If the potential of the ring assembly 112 is to be significantly changed (S10: Yes), the processing unit 2a1 controls the switch mechanism 38 to supply a bias RF signal to the electrode 50 having a large capacitance with the ring assembly 112 (S11), and ends the processing.

[0054] On the other hand, if the potential of the ring assembly 112 is not to be changed significantly (S10: No), the processing unit 2a1 determines whether to change the potential of the ring assembly 112 to a smaller value (S12). If the potential of the ring assembly 112 is to be changed to a smaller value (S12: Yes), the processing unit 2a1 controls the switch mechanism 38 to supply a bias RF signal to the electrode 50 having the smallest capacitance with the ring assembly 112 (S13), and ends the process.

[0055] On the other hand, if the potential of the ring assembly 112 is not to be decreased (S12: No), the processing unit 2a1 ends the process.

[0056] In the above embodiment, an example has been described in which three electrodes 50 (electrodes 50a-50c) are provided in the portion of the ceramic member 1111a facing the ring assembly 112. However, the disclosed technology is not limited to this. The number of electrodes 50 may be two, or may be four or more.

[0057] In the above embodiment, the controller 2 controls the switch mechanism 38 to supply bias RF signals to the plurality of electrodes 50 individually. However, the disclosed technology is not limited to this. The controller 2 may control the switch mechanism 38 to supply bias RF signals to one or more electrodes 50.

[0058] 9A is a diagram showing another example of electrode arrangement. In FIG. 9A, n electrodes 50a-50n are provided in a portion of the ceramic member 1111a facing the ring assembly 112. The electrodes 50a-50n are provided at the same depth from the annular region 111b. The electrodes 50a-50n have a surface area S １ -S ｎ The ratio of the areas is 2 ｎ-1The electrodes 50a-50n are each connected to a switch mechanism 38. The switch mechanism 38 has built-in switches that are individually conductive to the electrodes 50a-50n, and is configured to be able to supply a bias RF signal to the electrodes 50a-50n by switching each switch on and off. The control unit 2 controls the on and off states of each switch of the switch mechanism 38 so as to supply a bias RF signal to one or more electrodes 50. FIG. 9B is a diagram showing an example of a combination of on and off states of the switches. FIG. 9B shows the area S of each of 50a-50n. １ -S ｎ The On and Off states of the conductive switches are shown for each On / Off pattern of each switch. The On and Off states of the switches are indicated by a "●". Also, FIG. 9B shows the total area of ​​the electrodes 50 to which the bias RF signal is supplied by the switches that are turned On. The total area of ​​the electrodes 50 is calculated by dividing the area S １ The on / off patterns of each switch are determined so that the ratio of the total area of ​​the electrodes 50 to which the bias RF signal is supplied increases by 1. This allows the total capacitance between the electrode 50 whose switch is turned on and the ring assembly 112 to be changed in constant increments, thereby enabling the potential of the ring assembly to be controlled in increments.

[0059] In the above embodiment, a case has been described in which a plurality of electrodes 50 are formed in an annular shape corresponding to the annular region 111b of the electrostatic chuck 1111, and the potential of the entire annular region 111b is controlled. However, the disclosed technology is not limited to this. The annular region 111b of the electrostatic chuck 1111 may be divided into a plurality of zones, and a plurality of electrodes 50 may be provided in each zone, so that the potential can be controlled for each zone.

[0060] FIG. 10A is a diagram showing an example in which the annular region 111b of the electrostatic chuck 1111 is divided into multiple zones 90. FIG. 10A shows a case in which the annular region 111b is divided into n zones 90 in the circumferential direction. In this case, multiple electrodes 50 and a switch mechanism 38 are provided for each zone 90. In each zone 90, multiple electrodes 50 are arranged according to the shape of the zone 90. FIG. 10B is a cross-sectional view showing an example of the configuration of the main body 111 when multiple electrodes 50 are provided for each zone 90. In FIG. 10B, three electrodes 50a-50c and a switch mechanism 38 are provided in zone 3 and zone n, respectively. The control unit 2 can control the potential for each zone 90 of the annular region 111b by controlling the on / off of each switch of the switch mechanism 38 for each zone 90.

[0061] In the above embodiment, an example has been described in which a bias RF signal is supplied to the electrostatic electrode 1111b and the switch mechanism 38 via the base 1110. However, the disclosed technology is not limited to this. For example, in the configurations of Figures 2A and 3A, the wiring 36 and the wiring 39 may be connected to the output side of the impedance matching circuit 35 of the wiring 34, and the bias RF signal may be supplied to the electrostatic electrode 1111b and the switch mechanism 38 without passing through the base 1110.

[0062] The bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In the above embodiment, the potential of the ring assembly can be controlled by varying the total capacitance between the electrode 50 and the ring assembly 112, so a bias RF signal in the lower frequency range is more effective. In particular, it is desirable for the bias RF signal to have a frequency in the range of 100 kHz to 13 MHz.

[0063] In the above embodiment, the bias power that attracts charged particles in the plasma is high-frequency power (bias RF signal). However, the disclosed technology is not limited to this. The bias power may be a pulsed voltage. For example, the first DC generator 32a may generate a pulsed DC signal in the range of 100 kHz to 60 MHz, and the generated DC signal may be supplied as bias power to the electrostatic electrode 1111b and the switch mechanism 38. Note that even when the bias RF signal is a pulsed DC signal, it is desirable to generate a pulsed DC signal in the range of 100 kHz to 13 MHz, just as in the case of high-frequency power (bias RF signal).

[0064] The above describes the embodiment. As described above, the plasma processing system according to the embodiment includes a plasma processing chamber 10, an electrostatic chuck 1111 (stage), multiple electrodes 50, a power supply, a switch mechanism 38 (switch unit), and a controller 2. The plasma processing chamber 10 is configured to be capable of generating plasma therein. The electrostatic chuck 1111 is disposed within the plasma processing chamber 10 and is formed of a dielectric material. A substrate W can be placed thereon, and a ring assembly 112 can be placed around the substrate W. The multiple electrodes 50 are provided inside the electrostatic chuck 1111 at portions facing the ring assembly 112. The power supply is configured to supply bias power for attracting charged particles in the plasma. The switch mechanism 38 is configured to supply bias power supplied from the power supply to the multiple electrodes 50 individually. The controller 2 controls the switch mechanism 38. This allows the plasma processing system to control the potential of the ring assembly 112 without providing an elevator mechanism.

[0065] The electrodes 50 may be provided at different depths from the annular region 111b of the electrostatic chuck 1111 on which the ring assembly 112 is mounted. The electrodes 50 may be provided at the same depth from the annular region 111b of the electrostatic chuck 1111 on which the ring assembly 112 is mounted. The electrodes 50 may be formed to have the same area. The electrodes 50 may be formed to different areas. The plasma processing system can change the capacitance between the electrodes 50 and the ring assembly 112 by varying the depths or areas of the electrodes 50 from the annular region 111b. The plasma processing system can control the potential of the ring assembly 112 by changing the number of electrodes 50 that supply bias power, even if the capacitance between the electrodes 50 and the ring assembly 112 is the same.

[0066] The number of electrodes 50 is n (n is a natural number of 2 or more), and the ratio of the areas of the electrodes 50 is 2. ｎ-1 This allows the plasma processing system to change the total capacitance between itself and the ring assembly 112 in steps by a constant amount, thereby controlling the potential of the ring assembly in steps.

[0067] Furthermore, when the potential of the ring assembly 112 is to be increased, the control unit 2 controls the switch mechanism 38 to supply bias power to the electrode 50 having a large capacitance with the ring assembly 112, and when the potential of the ring assembly 112 is to be decreased, the control unit 2 controls the switch mechanism 38 to supply bias power to the electrode 50 having a small capacitance with the ring assembly 112. In this way, the plasma processing system can control the potential of the ring assembly 112.

[0068] Furthermore, the control unit 2 controls the switch mechanism 38 to supply bias power to the electrode 50 having a large capacitance with the ring assembly 112 in accordance with wear of the ring assembly 112. This allows the plasma processing system to suppress tilting from occurring around the periphery of the substrate W.

[0069] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0070] Furthermore, the following supplementary notes are disclosed regarding the above-described embodiment.

[0071] (Supplementary Note 1) A plasma processing apparatus comprising: a chamber configured to be able to generate plasma inside; a stage disposed within the chamber, formed of a dielectric, on which a substrate can be placed and on which a ring assembly can be placed around the substrate; a plurality of electrodes provided inside the stage in a portion facing the ring assembly; a power supply configured to be able to supply bias power for attracting charged particles in the plasma; a switch unit configured to be able to supply bias power supplied from the power supply to the plurality of electrodes individually; and a control unit that controls the switch unit.

[0072] (Supplementary Note 2) The plasma processing apparatus according to Supplementary Note 1, wherein the plurality of electrodes are provided at different depths from a region of the stage on which the ring assembly is placed.

[0073] (Supplementary Note 3) The plasma processing apparatus according to Supplementary Note 1, wherein the plurality of electrodes are provided at the same depth from a region of the stage on which the ring assembly is placed.

[0074] (Supplementary Note 4) The plasma processing apparatus according to any one of Supplementary Notes 1 to 3, wherein the plurality of electrodes have the same surface area facing the ring assembly.

[0075] (Supplementary Note 5) The plasma processing apparatus according to any one of Supplementary Notes 1 to 3, wherein the plurality of electrodes have surfaces facing the ring assembly with different areas.

[0076] (Note 6) The number of the plurality of electrodes is n (n is a natural number of 2 or more), and the ratio of the area of ​​the surface facing the ring assembly to each other is 2. ｎ-1The plasma processing apparatus according to claim 5, wherein the plasma processing apparatus is formed so as to have the following properties.

[0077] (Supplementary Note 7) The plasma processing apparatus according to any one of Supplementary Notes 1 to 6, wherein the plurality of electrodes are arranged so as not to overlap each other.

[0078] (Appendix 8) A plasma processing apparatus described in any one of Appendices 1-7, wherein the control unit controls the switch unit to supply the bias power to an electrode having a large capacitance with the ring assembly when increasing the potential of the ring assembly, and controls the switch unit to supply the bias power to an electrode having a small capacitance with the ring assembly when decreasing the potential of the ring assembly.

[0079] (Supplementary Note 9) The plasma processing apparatus according to any one of Supplementary Notes 1 to 7, wherein the control unit controls the switch unit to supply the bias power to an electrode having a larger capacitance with the ring assembly in accordance with wear of the ring assembly.

[0080] (Supplementary Note 10) The plasma processing apparatus according to any one of Supplementary Notes 1 to 9, wherein the power supply is a high-frequency power supply capable of supplying high-frequency power as the bias power.

[0081] (Supplementary Note 11) The plasma processing apparatus according to any one of Supplementary Notes 1 to 9, wherein the power supply is a DC power supply capable of generating a pulsed voltage as the bias power.

[0082] (Supplementary Note 12) A potential control method for a plasma processing apparatus having: a chamber configured to be able to generate plasma inside; a stage disposed within the chamber, formed of a dielectric, on which a substrate can be placed and on which a ring assembly can be placed around the substrate; a plurality of electrodes provided inside the stage facing the ring assembly; a power supply configured to be able to supply bias power for attracting charged particles in the plasma; a switch unit configured to be able to supply bias power supplied from the power supply to the plurality of electrodes individually; and a control unit that controls the switch unit, wherein the control unit performs the steps of: when increasing the potential of the ring assembly, controlling the switch unit to supply the bias power to an electrode having a large electrostatic capacitance with the ring assembly; and when decreasing the potential of the ring assembly, controlling the switch unit to supply the bias power to an electrode having a small electrostatic capacitance with the ring assembly.

[0083] 1 Plasma processing apparatus 2 Control unit 2a Computer 2a1 Processing unit 2a2 Memory unit 2a3 Communication interface 10 Plasma processing chamber 11 Substrate support 30 Power supply 31 RF power supply 31a First RF generation unit 31b Second RF generation unit 32 DC power supply 32a First DC generation unit 32b Second DC generation unit 34, 36, 37a-37c, 39 Wiring 35 Impedance matching circuit 38 Switch mechanism 40 Exhaust system 50, 50a-50c Electrodes 60a, 60b Path 61a, 62a Resistor 61b, 62b Capacitor 80 Model 81, 82a-82c, 84, 85 Line 90 Zone 111 Main body 111a Central region 111b Annular region 112 Ring assembly 1110 Base 1110a Flow path 1111 Electrostatic chuck 1111a Ceramic member 1111b Electrostatic electrode SW1-SW3 Switches W Substrate

Claims

1. A plasma processing apparatus comprising: a chamber configured to be able to generate plasma inside; a stage disposed within the chamber, formed of a dielectric material, on which a substrate can be placed and on which a ring assembly can be placed around the substrate; a plurality of electrodes provided in a portion of the stage facing the ring assembly; a power supply configured to be able to supply bias power for attracting charged particles in the plasma; a switch unit configured to be able to supply bias power supplied from the power supply to the plurality of electrodes individually; and a control unit that controls the switch unit.

2. The plasma processing apparatus according to claim 1, wherein the plurality of electrodes are provided at different depths from a region of the stage on which the ring assembly is placed.

3. The plasma processing apparatus according to claim 1, wherein the plurality of electrodes are provided at the same depth from the region of the stage on which the ring assembly is placed.

4. The plasma processing apparatus according to claim 1, wherein the plurality of electrodes are formed to have the same area, that is, the surfaces facing the ring assembly are the same.

5. The plasma processing apparatus according to claim 1, wherein the plurality of electrodes have different areas of the surfaces facing the ring assembly.

6. The number of the electrodes is n (n is a natural number of 2 or more), and the ratio of the area of ​​the surface facing the ring assembly to each other is 2. ｎ-1 The plasma processing apparatus according to claim 5 , wherein the plasma processing apparatus is configured to:

7. The plasma processing apparatus according to claim 1, wherein the plurality of electrodes are arranged so as not to overlap each other.

8. The plasma processing apparatus of claim 1, wherein the control unit controls the switch unit to supply the bias power to an electrode having a large capacitance with the ring assembly when the potential of the ring assembly is increased, and controls the switch unit to supply the bias power to an electrode having a small capacitance with the ring assembly when the potential of the ring assembly is decreased.

9. The plasma processing apparatus according to claim 1, wherein the control unit controls the switch unit so as to supply the bias power to an electrode having a larger electrostatic capacitance with the ring assembly in accordance with wear of the ring assembly.

10. The plasma processing apparatus according to claim 1, wherein the power supply is a high-frequency power supply capable of supplying high-frequency power as the bias power.

11. The plasma processing apparatus according to claim 1, wherein the power supply is a DC power supply capable of generating a pulsed voltage as the bias power.

12. A potential control method in a plasma processing apparatus having a chamber configured to be able to generate plasma inside; a stage disposed within the chamber, formed of a dielectric, on which a substrate can be placed and on which a ring assembly can be placed around the substrate; a plurality of electrodes provided in a portion of the stage facing the ring assembly; a power supply configured to be able to supply bias power for attracting charged particles in the plasma; a switch unit configured to be able to supply bias power supplied from the power supply to the plurality of electrodes individually; and a control unit for controlling the switch unit, wherein the control unit executes the steps of: when increasing the potential of the ring assembly, controlling the switch unit so as to supply the bias power to an electrode having a larger electrostatic capacitance with the ring assembly; and when decreasing the potential of the ring assembly, controlling the switch unit so as to supply the bias power to an electrode having a smaller electrostatic capacitance with the ring assembly.