Substrate supporter, substrate processing apparatus and electrostatic adsorption method

Abstract

To suppress leakage of heat transfer gas.SOLUTION: A substrate supporter for supporting a substrate includes a base, an electrostatic chuck, and an edge ring. The electrostatic chuck is arranged above the base and has a substrate support surface for supporting the substrate. The edge ring is arranged to surround the substrate on the substrate support surface. The electrostatic chuck has a ring support surface for supporting the edge ring. The ring support surface has an inner edge lower than an outer edge.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a substrate support, a substrate processing apparatus, and an electrostatic adsorption method. [Background technology]

[0002] Patent Document 1 discloses a substrate processing apparatus. The substrate processing apparatus includes a supply unit that supplies a heat medium to a space between an electrostatic chuck on which a substrate is placed and a focus ring that is provided on the electrostatic chuck and surrounds the area where the substrate is placed. The substrate processing apparatus also includes a plurality of electrodes that are provided in an area inside the electrostatic chuck corresponding to the focus ring and to which a voltage is applied to attract the focus ring to the electrostatic chuck. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-122740 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology according to the present disclosure suppresses leakage of heat transfer gas. [Means for solving the problem]

[0005] One aspect of the present disclosure is a substrate support for supporting a substrate, comprising: a base; an electrostatic chuck disposed above the base and having a substrate support surface for supporting the substrate; and an edge ring disposed to surround the substrate on the substrate support surface, wherein the electrostatic chuck has a ring support surface for supporting the edge ring, and the ring support surface has an inner edge side that is lower than an outer edge side. [Effects of the Invention]

[0006] According to the present disclosure, leakage of heat transfer gas can be suppressed. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing the state of a conventional substrate support when the pressure inside a chamber is atmospheric. [Figure 2] FIG. 10 is a diagram showing the state of a conventional substrate support when the chamber is being evacuated. [Figure 3] FIG. 1 is an explanatory diagram schematically illustrating a configuration of a plasma processing system. [Figure 4] 1 is a vertical cross-sectional view showing an outline of the configuration of a plasma processing apparatus; [Figure 5] 1 is a cross-sectional view of a substrate support in a plasma processing chamber when the entire periphery of the substrate support is at atmospheric pressure. [Figure 6] FIG. 6 is a partially enlarged cross-sectional view of FIG. 5. [Figure 7] FIG. 2 shows a view of the essential parts of the substrate support when the plasma processing chamber is depressurized. [Figure 8] 10 is a flowchart illustrating an example of a method for electrostatically attracting an edge ring. [Figure 9] FIG. 10 is a diagram illustrating a state of the electrostatic chuck during the step of placing the edge ring. [Figure 10] 10A and 10B are diagrams showing other examples of the ring support surface. [Figure 11] 10A and 10B are diagrams showing other examples of the ring support surface. [Figure 12] 10A and 10B are diagrams showing other examples of the ring support surface. [Figure 13] 10A and 10B are diagrams illustrating other examples of a ring support surface and an edge ring. [Figure 14] 10A and 10B are diagrams for explaining an example of a form in which a voltage is applied to an electrode for electrostatic attraction of an edge ring. [Figure 15] 10A and 10B are diagrams for explaining an example of a form in which a voltage is applied to an electrode for electrostatic attraction of an edge ring. [Figure 16] FIG. 10 is a cross-sectional view showing another example of an edge ring. [Figure 17] FIG. 10 shows an example of a substrate support further comprising a cover ring. [Figure 18] FIG. 10 is a diagram showing another example of a substrate support surface. DETAILED DESCRIPTION OF THE INVENTION

[0008] In the manufacturing process of semiconductor devices, plasma processing is performed on substrates such as semiconductor wafers (hereinafter referred to as "wafers"), in which plasma is generated by exciting a processing gas, and the substrate is processed by the plasma.

[0009] Plasma processing is performed in a substrate processing apparatus. The substrate processing apparatus generally includes a substrate support and a chamber. The substrate support includes a base and an electrostatic chuck disposed above the base and having a substrate support surface for supporting a substrate. The chamber is configured to be depressurized and accommodates the substrate support. In addition, an edge ring is disposed on the electrostatic chuck so as to surround the substrate supported on the substrate support surface in order to improve the uniformity of plasma processing on the substrate. The edge ring is supported on the ring support surface of the electrostatic chuck, which is formed to surround the substrate support surface, and is electrostatically attracted.

[0010] Furthermore, the substrate support is configured to have a flow path formed therein through which a temperature-controlling fluid flows, and to supply a heat transfer gas such as He (helium) gas between the ring support surface of the electrostatic chuck and the edge ring, so that the temperature of the edge ring can be controlled even if it rises due to heat input from the plasma during plasma processing.

[0011] 1, the ring support surface 501a of the electrostatic chuck 501 of the substrate support device 500 and the lower surface of the edge ring 502 are each formed of, for example, a substantially horizontal flat surface. However, even if the ring support surface 501a of the electrostatic chuck 501 is a substantially horizontal flat surface when the pressure inside the chamber 503 is atmospheric, it is deformed from the substantially horizontal flat surface when the pressure inside the chamber 503 is reduced during plasma processing, for example, as shown in FIG. 2. The reason for this is as follows.

[0012] That is, the lower surface of the peripheral edge of the substrate support 500 is fixed to the electrostatic chuck 501. Due to the structure of the chamber 503, even if the pressure inside the chamber 503 is reduced and the surroundings of the upper part of the substrate support 500 (for example, the upper surface of the base 504 and the electrostatic chuck 501) become a reduced-pressure atmosphere, the surroundings of the central part of the lower surface of the substrate support 500 remain in an atmospheric pressure atmosphere. Therefore, when the pressure inside the chamber 503 is reduced, the base 504 and the electrostatic chuck 501 are deformed such that their central parts protrude upward, and the ring support surface 501a is also deformed from a substantially horizontal flat surface.

[0013] When the edge ring 502 is deformed as described above, even though it is electrostatically attracted, it does not deform in the same way as the ring support surface 501a, and as a result, a gap of 5 μm to 20 μm in height is generated between the ring support surface 501a and the lower surface of the edge ring 502. This causes leakage of heat transfer gas such as He (helium) gas through the gap.

[0014] The technology disclosed herein suppresses leakage of heat transfer gas. Hereinafter, a substrate support, a substrate processing apparatus, and an electrostatic chucking method according to the present embodiment will be described with reference to the drawings. Note that in this specification and the drawings, elements having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0015] <Plasma processing system> First, a plasma processing system according to one embodiment will be described with reference to Fig. 3. Fig. 3 is an explanatory diagram that schematically shows the configuration of the plasma processing system.

[0016] In one embodiment, the plasma processing system includes a plasma processing apparatus 1 as an example of a substrate processing apparatus and a controller 2. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed within the plasma processing chamber 10 and has a substrate support surface for supporting a substrate.

[0017] 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 200 kHz to 150 MHz.

[0018] The controller 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The controller 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 controller 2 may be included in the plasma processing apparatus 1. The controller 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control operations based on programs stored in the storage unit 2a2. 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).

[0019] An example of the configuration of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1 will be described below with reference to Fig. 4. Fig. 4 is a vertical cross-sectional view showing an outline of the configuration of the plasma processing apparatus 1. In the plasma processing apparatus 1 of this embodiment, plasma processing is performed on a substrate (wafer) W, but the substrate W to be plasma processed is not limited to a wafer.

[0020] 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 sidewall 10a is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the plasma processing chamber 10 housing.

[0021] The substrate support 11 includes a main body 111 and an edge ring 112. The main body 111 has a central region (substrate support surface) 111a for supporting a substrate (wafer) W, and an annular region (ring support surface) 111b for supporting the edge ring 112. 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 edge ring 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.

[0022] In one embodiment, the main body 111 includes a base 113 and an electrostatic chuck 114. The base 113 includes a conductive member. The conductive member of the base 113 functions as a lower electrode. The electrostatic chuck 114 is disposed on the base 113. The upper surface of the electrostatic chuck 114 has a substrate support surface 111a. In one embodiment, the upper surface of the electrostatic chuck 114 also has a ring support surface 111b.

[0023] The edge ring 112 is disposed to surround the substrate W on the substrate support surface 111a.

[0024] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 114, the edge ring 112, and the substrate W to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow passage 113a, or a combination thereof. A heat transfer fluid, such as brine or a gas, flows through the flow passage 113a. In one embodiment, the flow passage 113a is formed in the base 113.

[0025] Furthermore, the substrate support 11 includes a heat transfer gas supply path 115 configured to supply a heat transfer gas between the lower surface of the edge ring 112 and the ring support surface 111b. The substrate support 11 may also include a heat transfer gas supply path configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111a. A heat transfer gas is supplied to each heat transfer gas supply path from a heat transfer gas supplier (not shown).

[0026] The heat transfer gas supply may include at least one gas source and at least one flow controller. In one embodiment, the heat transfer gas supply is configured to supply at least one heat transfer gas from a corresponding gas source to each heat transfer gas supply line via a corresponding flow controller. Each flow controller may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the heat transfer gas supply may include at least one flow modulation device that modulates or pulses the flow rate of the at least one heat transfer gas.

[0027] 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 a conductive member. The conductive member of the showerhead 13 functions as an 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.

[0028] 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.

[0029] 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), such as a source RF signal and a bias RF signal, to the conductive member of the substrate support 11 and / or the conductive member of the showerhead 13. This causes a plasma to be formed 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 conductive member of the substrate support 11, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0030] 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 the conductive members of the substrate support 11 and / or the conductive members of the showerhead 13 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 13 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 the conductive members of the substrate support 11 and / or the conductive members of the showerhead 13. The second RF generating unit 31b is coupled to the conductive members of the substrate support 11 via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). In one embodiment, the bias RF signal has a frequency lower than that of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 400 kHz to 13.56 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated bias RF signals are supplied to the conductive members of the substrate support 11. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0031] 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 a conductive member of the substrate support 11 and configured to generate a first DC signal. The generated first DC signal is applied to the conductive member of the substrate support 11. In one embodiment, the first DC signal may be applied to another electrode, such as an electrode in the electrostatic chuck 114. In one embodiment, the second DC generator 32b is connected to a conductive member of the showerhead 13 and configured to generate a second DC signal. The generated second DC signal is applied to the conductive member of the showerhead 13. In various embodiments, the first and second DC signals may be pulsed. 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.

[0032] 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.

[0033] <Substrate supporter> Next, the configuration of the above-mentioned substrate support 11 will be further described with reference to Fig. 4 and using Fig. 5 and Fig. 6. Fig. 5 is a cross-sectional view showing the state of the substrate support 11 in the plasma processing chamber 10, showing the state when the entire periphery of the substrate support 11 is at atmospheric pressure. Fig. 6 is a partially enlarged cross-sectional view of Fig. 5. However, the wafer W is not shown in Fig. 6.

[0034] As shown in FIG. 4, the substrate support 11 is accommodated in the plasma processing chamber 10. Specifically, the substrate support 11 is accommodated in the plasma processing chamber 10 so that the lower surface of the substrate support 11 is exposed to an atmosphere with a higher pressure than the reduced pressure inside the plasma processing chamber 10. More specifically, the substrate support 11 is accommodated in the plasma processing chamber 10 so that its lower surface blocks an opening 10f provided in the bottom of the plasma processing chamber 10. For example, the opening 10f can be blocked by fixing the lower surface of the peripheral edge of the substrate support 11 to the bottom of the plasma processing chamber 10 via cylindrical legs 15 provided to surround the outer periphery of the opening 10f. The legs 15 are made of an insulator. In one embodiment, an O-ring 16 serving as a seal member is provided between the bottom of the plasma processing chamber 10 and the legs 15, as shown in FIG. 5.

[0035] As previously described, the substrate support 11 includes a body portion 111 and an edge ring 112 , and in one embodiment, the body portion 111 includes a base 113 and an electrostatic chuck 114 .

[0036] In one embodiment, the base 113 is made of a conductive material such as Al, etc. The base 113 and the electrostatic chuck 114 are integrated together by, for example, adhesion.

[0037] The electrostatic chuck 114 is integrally formed of a central portion 200 having a substrate support surface 111a and an outer peripheral portion 201 having a ring support surface 111b. The central portion 200 and the outer peripheral portion 201 of the electrostatic chuck 114 may be separate bodies. The central portion 200 is provided so as to protrude from the outer peripheral portion 201, and the substrate support surface 111a of the central portion 200 is higher than the ring support surface 111b of the outer peripheral portion 201.

[0038] The edge ring 112, supported by the ring support surface 111b, is a component disposed to surround the substrate W on the substrate support surface 111a. The edge ring 112 is formed in an annular shape, more specifically, in a circular ring shape in a plan view. In one embodiment, the lower surface of the edge ring 112 is formed as a flat surface whose height in a cross-sectional view is constant from the inner edge side to the outer edge side and that is approximately horizontal when supported by the substrate support surface 111a. The edge ring 112 is made of a material such as SiC, Si, SiO2, W, WC, or ceramics.

[0039] The central portion 200 of the electrostatic chuck 114 is formed with a diameter smaller than the diameter of the substrate W, for example, so that when the substrate W is placed on the substrate support surface 111a, the peripheral portion of the substrate W protrudes from the central portion 200 of the electrostatic chuck 114. 6, the edge ring 112 has a step formed on its upper portion, and the upper surface of the outer periphery is higher than the upper surface of the inner periphery. The inner periphery of the edge ring 112 may be formed to extend below the peripheral edge of the substrate W that extends beyond the central portion 200 of the electrostatic chuck 114. In other words, the inner diameter of the edge ring 112 may be formed to be smaller than the outer diameter of the substrate W.

[0040] Furthermore, an electrode 210 for electrostatically attracting the substrate W is provided at a central portion 200 of the electrostatic chuck 114. An electrode 211 for electrostatically attracting the edge ring 112 is provided at an outer peripheral portion 201 of the electrostatic chuck 114. In one embodiment, the electrode 211 is a bipolar electrode including a pair of electrodes 211a and 211b. For example, the first electrode 211a and the second electrode 211b are formed in an annular shape in a plan view and are arranged concentrically with each other, with the first electrode 211a located on the inner side and the second electrode 211b located on the outer side. The first electrode 211a and the second electrode 211b may each be divided along the circumferential direction.

[0041] A DC voltage from a DC power supply (not shown) is applied to the electrode 210. The resulting electrostatic force attracts and holds the substrate W on the substrate support surface 111a. Similarly, a DC voltage from a DC power supply is applied to the electrode 211. Specifically, the DC voltage from the DC power supply is applied to the electrode 211 so that a potential difference is generated between the first electrode 211a and the second electrode 211b. The resulting electrostatic force attracts and holds the edge ring 112 to the ring support surface 111b.

[0042] As described above, the substrate support 11 also includes a heat transfer gas supply path 115 configured to supply a heat transfer gas between the lower surface of the edge ring 112 and the ring support surface 111b. In one embodiment, a heat transfer gas supply port 220 is formed in the ring support surface 111b provided on the outer circumferential portion 201 of the electrostatic chuck 114. The heat transfer gas supplied to the heat transfer gas supply path 115 is supplied from the heat transfer gas supply port 220 to between the lower surface of the edge ring 112 and the ring support surface 111b. The heat transfer gas supply port 220 is connected to a heat transfer gas supply unit (not shown). The heat transfer gas supply unit includes, for example, a gas source 21 of the heat transfer gas and a flow rate controller that adjusts the supply amount. The flow rate controller 22 includes, for example, a flow rate controller such as a mass flow controller and a valve.

[0043] In one embodiment, the heat transfer gas supply port 220 also serves as an adsorption port. By evacuating the space between the ring support surface 111b and the edge ring 112 through the heat transfer gas supply port 220, which functions as an adsorption port, the edge ring 112 can be vacuum-adsorbed onto the ring support surface 111b. The heat transfer gas supply port 220, which functions as an adsorption port, is connected to an exhaust system (not shown). The exhaust system includes, for example, an exhaust rate adjustment valve and a vacuum pump. The adsorption port and the heat transfer gas supply port 220 may be provided separately.

[0044] Furthermore, the ring support surface 111b of the electrostatic chuck 114 is formed so that its inner edge is lower than its outer edge when the plasma processing chamber 10 is not depressurized, i.e., when there is no load. For example, the ring support surface 111b of the electrostatic chuck 114 is configured as an inclined surface whose inner edge is lower than its outer edge. The radial width of the electrostatic chuck 114 is, for example, 15 mm, and the height difference between the inner and outer circumferential ends of the electrostatic chuck 114 is, for example, 8 μm. The angle of the inclined surface constituting the ring support surface 111b with respect to the horizontal plane (when there is no load) is, for example, 0.03° to 0.06°.

[0045] The inner diameter of the edge ring 112 supported by the ring support surface 111b as described above is set, for example, as follows: That is, the inner diameter of the edge ring 112 is set so that a gap is formed between the inner peripheral surface of the edge ring 112 (hereinafter referred to as the ring inner peripheral surface) and the outer peripheral surface of the central portion 200 of the electrostatic chuck 114. More specifically, the inner diameter of the edge ring 112 is set so that the ring inner peripheral surface does not come into contact with the outer peripheral surface of the central portion 200 of the electrostatic chuck 114 when the edge ring 112 is electrostatically attracted as indicated by the dotted line in FIG.

[0046] Next, the effect of forming ring support surface 111b as described above will be described. Fig. 7 is a diagram showing the main part of substrate support 11 when plasma processing chamber 10 is depressurized, and does not show flow path 113a, heat transfer gas supply path 115, electrodes 210, 211, etc.

[0047] When the pressure inside the plasma processing chamber 10 is reduced, a reduced-pressure atmosphere is created around the upper portion of the substrate support 11 (e.g., the upper surface of the base 113 and the electrostatic chuck 114). However, even when the pressure inside the plasma processing chamber 10 is reduced, the pressure around the central portion of the lower surface of the substrate support 11 (specifically, the lower surface of the base 113) remains at the same pressure as before the pressure reduction began, i.e., the atmospheric pressure is maintained. As a result, the base 113 and the electrostatic chuck 114 are deformed such that their central portions protrude upward. When this deformation occurs, as described with reference to FIGS. 1 and 2, if the ring support surface 111b is a substantially horizontal flat surface in an unloaded state, unlike the present embodiment, heat transfer gas leaks into the plasma processing space 10s from a gap between the ring support surface 111b and the lower surface of the edge ring 112.

[0048] In contrast, in this embodiment, the ring support surface 111b is formed so that its inner edge is lower than its outer edge when no load is applied. Therefore, as shown in FIG. 7, when the base 113 and the electrostatic chuck 114 deform so that their central portions protrude upward, and the outer peripheral portion 201 of the electrostatic chuck 114 also deforms, the ring support surface 111b approaches a substantially horizontal position. Therefore, compared to when the ring support surface 111b is a substantially horizontal, flat surface when no load is applied, the gap between the ring support surface 111b and the lower surface of the edge ring 112 when the pressure inside the plasma processing chamber 10 is reduced can be made smaller. This prevents the heat transfer gas from leaking through the gap.

[0049] Furthermore, if the gap is small, when the edge ring 112 is electrostatically attracted to the ring support surface 111b, the edge ring 112 can be deformed to bring the lower surface of the edge ring 112 and the ring support surface 111b into close contact over substantially the entire surface, thereby further suppressing leakage of the heat transfer gas from the gap.

[0050] Next, a method for electrostatically attracting the edge ring 112 will be described with reference to Fig. 8 and Fig. 9. Fig. 8 is a flowchart illustrating an example of the method for electrostatically attracting the edge ring 112. Fig. 9 is a diagram showing the state of the electrostatic chuck 114 during the step of placing the edge ring.

[0051] First, as shown in FIG. 8 , for example, an operator places the edge ring 112 on the ring support surface 111b of the electrostatic chuck 114, positioning it with respect to the substrate support surface 111a (step S1). The edge ring 112 is positioned with respect to the substrate support surface 111a using a positioning jig J, as shown in FIG. 8 . In one embodiment, the positioning jig J is inserted between the outer circumferential surface of the central portion 200 of the electrostatic chuck 114 and the inner circumferential surface of the edge ring 112. By using such a positioning jig J, for example, it is possible to keep the distance between the outer circumferential surface of the central portion 200 of the electrostatic chuck 114 and the inner circumferential surface of the edge ring 112 constant along the circumferential direction of the electrostatic chuck 114.

[0052] Next, the edge ring 112 supported on the ring support surface 111b is vacuum-adsorbed (step S2). Specifically, the space between the ring support surface 111b and the lower surface of the edge ring 112 is evacuated through the heat transfer gas supply port 220 serving as an adsorption port, and the edge ring 112 is vacuum-adsorbed to the ring support surface 111b.

[0053] Thereafter, the positioning jig J is removed from the electrostatic chuck 114 by an operator (step S3).

[0054] Next, the edge ring 112 supported on the ring support surface 111b is electrostatically attracted (step S4) at the same time as the depressurization of the plasma processing chamber 10 begins. Specifically, at the same time as the depressurization of the plasma processing chamber 10 begins, a DC voltage is applied to the electrode 211, and the resulting electrostatic force electrostatically attracts the edge ring 112 to the ring support surface 111b. This completes a series of electrostatic adsorption processes for the edge ring 112.

[0055] After the edge ring 112 is adsorbed, a heat transfer gas is supplied between the ring support surface 111b and the edge ring 112 at a desired timing (for example, at the start of plasma processing).

[0056] As described above, in this embodiment, the ring support surface 111b of the substrate support 11 is formed so that the inner edge side is lower than the outer edge side under no load. Therefore, according to this embodiment, when the plasma processing chamber 10 is depressurized, the gap between the lower surface of the edge ring 112 and the ring support surface 111b can be reduced, thereby preventing the heat transfer gas from leaking from the gap. As a result, problems caused by the leakage of the heat transfer gas can also be prevented.

[0057] As a method for reducing the gap between the lower surface of the edge ring 112 and the ring support surface 111b when the plasma processing chamber 10 is depressurized, which differs from the method of this embodiment, the following method for suppressing deformation of the substrate support is conceivable. Specifically, the thickness or material of the electrostatic chuck 114 is changed to increase rigidity, thereby suppressing deformation of the substrate support 11 and reducing the gap. Another conceivable method is to fasten the center of the lower surface of the substrate support 11 to the plasma processing chamber 10, thereby suppressing deformation of the substrate support 11 when the plasma processing chamber 10 is depressurized and reducing the gap. However, the structure of the substrate support 11 is designed with an emphasis on the characteristics of the substrate attraction region (e.g., attraction characteristics, heat dissipation characteristics). Therefore, imposing restrictions on the structure of the substrate support 11 to suppress deformation of the substrate support 11 is undesirable because it reduces design freedom. In contrast, in this embodiment, the gap can be reduced by simply slightly changing the shape of the ring support surface 111b from the conventional one, so design freedom is not reduced.

[0058] In this embodiment, the ring support surface 111b is configured as an inclined surface. However, the shape of the ring support surface 111b is not limited to this, and it is sufficient that the inner edge side is formed lower than the outer edge side in the no-load state, specifically, it is sufficient that the angle of the surface connecting the inner edge and the outer edge with the horizontal in the no-load state is 0.03° to 0.06°.

[0059] For example, like a ring support surface 300 in FIG. 10, it may be formed in a stepped shape that increases in height from the inner edge side to the outer edge side in an unloaded state. Also, like the ring support surface 310 in FIG. 11, it may be formed so that there is a step between the inner edge side and the outer edge side, and the inner edge side is higher in the no-load state. Furthermore, like the ring support surface 320 in FIG. 12, it may be formed as a curved surface that rises from the inner edge side toward the outer edge side in the no-load state. Even with ring support surfaces 300, 310, and 320, the gap between the ring support surfaces 300, 310, and 320 and the lower surface of edge ring 112 can be made smaller when the pressure in plasma processing chamber 10 is reduced, compared to ring support surface 111b, which is configured as a substantially horizontal flat surface in an unloaded state. This makes it possible to prevent heat transfer gas from leaking through the gap.

[0060] 13, a groove 331 communicating with the heat transfer gas supply port 220 may be formed in the ring support surface 330. The groove 331 is formed, for example, to extend along the circumferential direction of the electrostatic chuck 114. In one embodiment, the groove 331 is formed in a circular ring shape concentric with the electrostatic chuck 114 in a plan view. Furthermore, an upwardly recessed groove 341 may be formed in the lower surface of the edge ring 340 at a position corresponding to the heat transfer gas supply port 220. In one embodiment, the groove 341 is formed at a position facing the heat transfer gas supply port 220 when the plasma processing chamber 10 is depressurized and the electrostatic chuck 114 is deformed. The groove 341 is formed to extend, for example, along the circumferential direction of the edge ring 340. In one embodiment, the groove 341 is formed in a circular ring shape concentric with the edge ring 340 in a plan view.

[0061] By forming grooves 331 in the ring support surface 330 or grooves 341 in the underside of the edge ring 340, the heat transfer gas can be diffused in the circumferential direction. This further reduces the leakage of the heat transfer gas. This also improves the temperature control of the edge ring 112, thereby improving the uniformity of the temperature distribution in the edge ring 112.

[0062] The voltage applied to the electrode 211 is, for example, constant, but may be changed based on the temperature of the temperature-regulating fluid flowing through the flow path 113a, as will be described below. The change in the voltage applied to the electrode 211 based on the temperature of the temperature-regulating fluid is performed by the control unit 2.

[0063] If the lower surface of edge ring 112 is horizontal when supported by ring support surface 111b, it is preferable that ring support surface 111b also be horizontal when the plasma processing chamber 10 is depressurized and the base 113 and electrostatic chuck 114 are deformed. Therefore, in one embodiment, the plasma processing chamber 10 is designed so that ring support surface 111b is horizontal when the plasma processing chamber 10 is depressurized and the base 113 and electrostatic chuck 114 are deformed.

[0064] On the other hand, the electrostatic chuck 114 and the base 113 have different thermal expansion coefficients due to differences in the materials used to form them, with the base 113 having a larger thermal expansion coefficient. Therefore, when the temperature-controlling fluid flowing through the flow path 113a is high temperature, the base 113 thermally expands, and the electrostatic chuck 114 is pulled outward by the base 113. As a result, as shown in FIG. 14 , when the plasma processing chamber 10 is depressurized and the base 113 and the electrostatic chuck 114 are deformed, the ring support surface 111b may tilt downward toward the outer edge rather than remaining horizontal as designed. This tilt creates a gap between the lower surface of the edge ring 112 and the outer edge of the ring support surface 111b. Therefore, when the temperature-controlling fluid flowing through the flow path 113a is high temperature, in order to reduce the gap, the magnitude of the voltage applied to the outer second electrode 211b may be made larger than that of the inner first electrode 211a so that the outer edge of the edge ring 112 is more strongly electrostatically attracted by the electrode 211.

[0065] Furthermore, when the temperature-controlling fluid flowing through the flow path 113a is low, the base 113 thermally contracts, causing the electrostatic chuck 114 to be pulled inward by the base 113. As a result, as shown in FIG. 15 , when the plasma processing chamber 10 is depressurized and the base 113 and the electrostatic chuck 114 are deformed, the ring support surface 111b may tilt downward toward the inner edge rather than remaining horizontal as designed. This tilt creates a gap between the lower surface of the edge ring 112 and the inner edge of the ring support surface 111b. Therefore, when the temperature-controlling fluid flowing through the flow path 113a is low, in order to reduce the gap, the magnitude of the voltage applied to the inner first electrode 211a may be made larger than that of the outer second electrode 211b so that the inner edge of the edge ring 112 is more strongly electrostatically attracted by the electrode 211.

[0066] In the above description, the lower surface of the edge ring 112 has a constant height from the inner edge side to the outer edge side in a cross-sectional view and is horizontal when supported by the ring support surface 111b. However, as shown in FIG. 16, the lower surface of the edge ring 350 may be higher on the inner edge side than on the outer edge side in a cross-sectional view. With this shape, even if the ring support surface 111b tilts downward toward the outer edge side when the plasma processing chamber 10 is depressurized as shown in FIG. 14, the lower surface of the edge ring 350 and the ring support surface 111b can be in close contact over substantially the entire surface.

[0067] 17, the substrate support 360 may include a cover ring 361 and another ring support surface 362. The cover ring 361 is a member arranged to cover the outer surface of the edge ring 112, and the ring support surface 362 is formed to surround the outside of the ring support surface 111b and support the cover ring 361. If the substrate support 360 further includes a configuration for supplying heat transfer gas between the lower surface of the cover ring 361 and the ring support surface 362, the ring support surface 362 may be formed so that its inner edge is lower than its outer edge, similar to the ring support surface 111b. This makes it possible to prevent the heat transfer gas from leaking from the gap between the lower surface of the cover ring 361 and the ring support surface 362.

[0068] In one embodiment, the ring support surface 362 is provided on an annular insulating member 363 that surrounds the outer periphery of the electrostatic chuck 114 and the base 113 .

[0069] 18 , the substrate support surface 371 of the electrostatic chuck 370 may be formed in a concave shape that is recessed downward in cross section when the plasma processing chamber 10 is not depressurized. This allows the substrate support surface 371 to approach a substantially horizontal position when the plasma processing chamber 10 is depressurized and the electrostatic chuck 370 deforms so that its central portion protrudes upward. This reduces the gap between the lower surface of the substrate W and the substrate support surface 371 compared to when the substrate support surface 371 of the electrostatic chuck 370 is formed so as to be horizontal when the plasma processing chamber 10 is not depressurized. This prevents the heat transfer gas supplied between the lower surface of the substrate W and the substrate support surface 371 from leaking through the gap.

[0070] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive, and the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. [Explanation of symbols]

[0071] 1. Plasma processing equipment 10 Plasma Processing Chamber 11, 360 board supporter 111a Central area (board support surface) 111b Annular region (ring support surface) 112, 340, 350 Edge Ring 113 Foundation 114, 370 Electrostatic chuck 300, 310, 320, 330, 362 Ring support surface 371 Substrate support surface W substrate

Claims

1. A substrate support for supporting a substrate, The base and an electrostatic chuck disposed above the base and having a substrate support surface at a central portion thereof for supporting a substrate; an edge ring disposed to surround the substrate on the substrate support surface; the electrostatic chuck has a ring support surface for supporting the edge ring; an inner circumferential portion of the ring support surface is lower than an outer circumferential portion thereof, and a gap is formed between an inner circumferential portion of a lower surface of the edge ring when the edge ring is not attracted to the electrostatic chuck and an inner circumferential portion of the ring support surface.

2. A substrate support as described in claim 1, wherein the ring support surface has a first electrode and a second electrode on the inside and outside, respectively, for electrostatically adsorbing the edge ring.

3. A substrate support as described in claim 2, wherein a voltage is applied to the first electrode and the second electrode so that a potential difference occurs between the two electrodes.

4. Further comprising a flow path through which a temperature control fluid for the substrate flows, 4. The substrate support according to claim 3, wherein the magnitude of the voltage applied to the first electrode and the second electrode is changed based on the temperature of the temperature-regulating fluid flowing through the flow path.

5. A substrate support for supporting a substrate, comprising: The base and an electrostatic chuck disposed above the base and having a substrate support surface for supporting a substrate; an edge ring disposed to surround the substrate on the substrate support surface; a flow path through which a temperature control fluid for the substrate flows; the electrostatic chuck has a ring support surface for supporting the edge ring; the ring support surface has an inner edge side lower than an outer edge side, and has a first electrode and a second electrode on an inner side and an outer side, respectively, for electrostatically attracting the edge ring; a voltage is applied to the first electrode and the second electrode so as to generate a potential difference between the electrodes; The magnitude of the voltage applied to the first electrode and the second electrode is changed based on the temperature of a temperature-controlling fluid flowing through the flow path.

6. 6. The substrate support according to claim 1, wherein the ring support surface has a heat transfer gas supply port for supplying a heat transfer gas between the ring support surface and the edge ring.

7. The substrate support of claim 6 , wherein at least one of the lower surface of the edge ring or the ring support surface has a groove.

8. 8. The substrate support according to claim 1, wherein the ring support surface is configured as an inclined surface.

9. 9. The substrate support according to claim 8, wherein the angle of the inclined surface is 0.03° to 0.06°.

10. 8. The substrate support according to claim 1, wherein the ring support surface is configured as a curved surface that rises from an inner edge side toward an outer edge side.

11. The substrate support according to any one of claims 1 to 7, wherein the ring support surface has a step between the inner periphery and the outer periphery, or is formed in a stepped shape that becomes higher from the inner periphery to the outer periphery.

12. The edge ring is made of SiC, Si, SiO ２ 12. The substrate support according to claim 1, which is made of W, WC or ceramics.

13. A substrate support according to any one of claims 1 to 12; a processing chamber configured to be decompressible and accommodating the substrate support.

14. The substrate processing apparatus according to claim 13 , wherein the substrate support is accommodated in the processing chamber such that a central portion of a lower surface of the substrate support is exposed to an atmosphere having a higher pressure than the interior of the processing chamber, which is evacuated.

15. 1. A method for electrostatically attracting an edge ring to an electrostatic chuck of a substrate support in a substrate processing apparatus, comprising: the substrate processing apparatus includes a processing chamber configured to be depressurized and accommodating the substrate support; The substrate support includes: The base and an electrostatic chuck disposed above the base and having a substrate support surface for supporting a substrate; the edge ring disposed to surround the substrate on the substrate support surface, the electrostatic chuck has a ring support surface for supporting the edge ring; The ring support surface has an inner periphery lower than an outer periphery, suctioning the edge ring supported on the ring support surface of the substrate support; thereafter, reducing the pressure in the processing chamber, and deforming the base and the electrostatic chuck to bring an inner periphery of the ring support surface closer to a lower surface of the edge ring.

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