Thermally conductive member, plasma processing apparatus, and voltage control method

Abstract

Provided is a heat conductive member, a plasma processing apparatus, and a voltage control method, which can stably transfer heat and are easy to maintain. A heat conductive member is provided, which is disposed in a plasma processing apparatus having a first electrostatic chuck for holding a substrate in a processing container that provides a plasma processing space, a second electrostatic chuck disposed on an outer periphery of the first electrostatic chuck, an edge ring disposed on the second electrostatic chuck so as to surround an area in which the substrate is held, at least a portion of the edge ring being composed of an electrically conductive member, and an edge ring electrode to which a voltage for electrostatically attracting the edge ring to an area inside the second electrostatic chuck corresponding to the edge ring is applied, wherein the heat conductive member is disposed between the second electrostatic chuck and the edge ring.

Description

Technical Field

[0001] This disclosure relates to a thermally conductive component, a plasma processing apparatus, and a voltage control method. Background Technology

[0002] For example, Patent Document 1 discloses a plasma processing device in which a thermally conductive sheet made of a gel-like material is disposed between an electrostatic chuck and a focusing ring. The thermally conductive sheet has adhesive properties.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2008-16727 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This disclosure provides a thermally conductive component that can stably transfer heat and is easy to maintain.

[0008] Solution for solving the problem

[0009] According to one aspect of this disclosure, a thermally conductive member is provided in a plasma processing apparatus, the plasma processing apparatus comprising: a first electrostatic chuck for placing a substrate within a processing container providing a plasma processing space; a second electrostatic chuck disposed on the outer periphery of the first electrostatic chuck; an edge ring disposed on the second electrostatic chuck in a manner that surrounds the area where the substrate is placed, at least a portion of the edge ring being composed of a conductive member; and an electrode for the edge ring, to which a voltage is applied for electrostatically adsorbing the edge ring in a region corresponding to the edge ring inside the second electrostatic chuck, wherein the thermally conductive member is disposed between the second electrostatic chuck and the edge ring.

[0010] The effects of the invention

[0011] According to one aspect, it is possible to provide a thermally conductive component that can stably transfer heat and is easy to maintain. Attached Figure Description

[0012] Figure 1 This is a cross-sectional schematic diagram illustrating an example of the plasma processing apparatus according to the embodiment.

[0013] Figure 2 This is a diagram showing a portion of the interface of the thermally conductive component involved in the embodiment, magnified.

[0014] Figure 3This is a diagram illustrating an example of the relationship between the thickness of the thermally conductive member (sheet) and the adsorption force involved in the embodiment.

[0015] Figure 4 This is a diagram showing a modified example of the structure of the thermally conductive component and the electrostatic chuck involved in the embodiment.

[0016] Figure 5 This is a flowchart illustrating an example of the voltage control method involved in the implementation.

[0017] Figure 6 This is a diagram used to illustrate the voltage control method involved in the implementation method.

[0018] Explanation of reference numerals in the attached figures

[0019] 1: Plasma processing apparatus; 10: Processing container; 10s: Plasma processing space; 14: Stage; 20: Electrostatic chuck; 20a: Electrode for substrate; 20c: First electrostatic chuck; 20e: Second electrostatic chuck; 21: Electrode for edge ring; 24: Edge ring; 25: Thermally conductive component; 29: Temperature sensor; 34: Upper electrode; 200: Control device; 201: Control unit; W: Substrate; TB: Surface plate. Detailed Implementation

[0020] The following description, with reference to the accompanying drawings, illustrates the manner in which this disclosure is carried out. In the drawings, the same reference numerals are sometimes used for the same structural parts, and repeated descriptions are omitted.

[0021] [Plasma Processing Device]

[0022] use Figure 1 The plasma processing apparatus 1 involved in the implementation method will be described below. Figure 1 This is a cross-sectional schematic diagram illustrating an example of the plasma processing apparatus according to the embodiment.

[0023] The plasma processing apparatus includes a processing container 10. A plasma processing space 10s is provided within the processing container 10. The processing container 10 has a generally cylindrical shape. The processing container 10 is formed, for example, of aluminum. A corrosion-resistant membrane is provided on the inner wall surface of the processing container 10. This membrane can be a ceramic such as alumina or yttrium oxide.

[0024] A passage 85 is formed on the side wall of the processing container 10. The substrate W is transported between the plasma processing space 10s and the outside of the processing container 10 through the passage 85. The passage 85 is opened and closed by a gate valve 86 provided along the side wall of the processing container 10.

[0025] A cylindrical support portion 26 is disposed at the bottom of the processing container 10, separated by an insulating plate 12 made of ceramic or the like. The support portion 26 supports the mounting stage 14 on the insulating plate 12. The mounting stage 14 is configured to support the substrate W in the plasma processing space 10s.

[0026] The stage 14 has a lower electrode 18 and an electrostatic chuck 20. The stage 14 may also have an electrode plate 16. The electrode plate 16 is formed of a conductor such as aluminum and has a generally disc-shaped form. The lower electrode 18 is disposed on the electrode plate 16. The lower electrode 18 is formed of a conductor such as aluminum and has a generally disc-shaped form. The lower electrode 18 is electrically connected to the electrode plate 16.

[0027] An electrostatic chuck 20 is disposed on the lower electrode 18. A substrate W is placed on the upper surface of the electrostatic chuck 20. The electrostatic chuck 20 has a first electrostatic chuck 20c disposed on one side (center) of the substrate W and a second electrostatic chuck 20e disposed on the side (outer periphery) of the first electrostatic chuck 20c near the disposed edge ring 24. In the embodiment, the first electrostatic chuck 20c and the second electrostatic chuck 20e are integral, but are not limited thereto and may be separate. Hereinafter, the first electrostatic chuck 20c and the second electrostatic chuck 20e will be collectively referred to as electrostatic chuck 20. The first electrostatic chuck 20 has a substrate electrode 20a and a body 20b. The body 20b has a generally disc-shaped shape and is formed of a dielectric. The substrate electrode 20a is a film electrode disposed within the body 20b. The substrate electrode 20a is connected to a power supply 22p via a switch 22s. When a DC voltage (hereinafter also referred to as "HV voltage") from a power supply 22p is applied to the electrode 20a of the substrate, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. This electrostatic attraction holds the substrate W on the electrostatic chuck 20.

[0028] An edge ring 24 is disposed on the mounting surface of the second electrostatic chuck 20e, which is a step provided at the periphery of the main body 20b, in a manner that surrounds the edge of the substrate W. The edge ring 24 is also referred to as a focusing ring. The edge ring 24 improves the in-plane uniformity of the plasma treatment of the substrate W. At least a portion of the edge ring 24 is made of a conductive member and can be formed of silicon (Si), silicon carbide (SiC), or quartz, etc.

[0029] An edge ring electrode 21 is provided inside the second electrostatic chuck 20e in the region corresponding to the edge ring 24, and a voltage is applied to electrostatically attract the edge ring 24. The edge ring electrode 21 is a film-like electrode arranged in a ring shape below the edge ring 24 within the main body 20b. The edge ring electrode 21 is connected to the power supply 23p via a switch 23s. When a DC voltage (hereinafter also referred to as "HV voltage") from the power supply 23p is applied to the edge ring electrode 21, an electrostatic attraction is generated between the electrostatic chuck 20 and the edge ring 24. This electrostatic attraction holds the edge ring 24 on the electrostatic chuck 20. A thermally conductive member 25 is disposed between the edge ring 24 and the main body 20b.

[0030] A flow path 28 is provided inside the lower electrode 18. A heat exchange medium (refrigerant, heat transfer medium) for temperature adjustment is supplied to the flow path 28 via a pipe 30a from a cooling unit (not shown) located outside the processing container 10. The heat exchange medium supplied to the flow path 28 returns to the cooling unit via a pipe 30b. In the plasma processing apparatus 1, the temperature of the substrate W placed on the electrostatic chuck 20 is adjusted by heat exchange between the heat exchange medium and the lower electrode 18.

[0031] A gas supply line 32 is provided in the plasma processing apparatus 1. The gas supply line 32 supplies heat transfer gas (e.g., He gas) from the heat transfer gas supply mechanism (not shown) to the space between the upper surface of the electrostatic chuck 20 and the lower surface of the substrate W.

[0032] The plasma processing apparatus 1 also includes an upper electrode 34. The upper electrode 34 is disposed above the stage 14. The upper electrode 34 is supported on the upper part of the processing container 10 via an insulating member 42 to close the upper opening of the processing container 10.

[0033] The upper electrode 34 has a top plate 36 and a support 38. The lower surface of the top plate 36 is the lower surface of the plasma processing space 10s side, defining the plasma processing space 10s. The top plate 36 can be formed of a low-resistance conductor or semiconductor with low Joule heat generation. The top plate 36 has a plurality of gas ejection holes 37 extending through the top plate 36 along its thickness direction.

[0034] The support body 38 supports the top plate 36 in a removable manner. The support body 38 is made of a conductive material such as aluminum. A gas diffusion chamber 40 is provided inside the support body 38. The support body 38 has multiple gas holes 41 extending downward from the gas diffusion chamber 40. The multiple gas holes 41 are respectively connected to multiple gas ejection holes 37. A gas inlet 62 is formed in the support body 38. The gas inlet 62 is connected to the gas diffusion chamber 40. The gas inlet 62 is connected to the gas supply pipe 64.

[0035] Gas supply pipe 64 is connected to valve assembly 70, flow controller assembly 68, and gas source assembly 66. Gas source assembly 66, valve assembly 70, and flow controller assembly 68 constitute the gas supply unit GS. Gas source assembly 66 includes multiple gas sources. Valve assembly 70 includes multiple on / off valves. Flow controller assembly 68 includes multiple flow controllers. The multiple flow controllers in flow controller assembly 68 are either mass flow controllers or pressure-controlled flow controllers. The multiple gas sources in gas source assembly 66 are connected to gas supply pipe 64 via corresponding flow controllers in flow controller assembly 68 and corresponding on / off valves in valve assembly 70.

[0036] In the plasma processing apparatus 1, a shield (not shown) is detachably installed along the inner wall of the processing container 10 and the outer periphery of the support 26. A partition 83 is provided between the support 26 and the side wall of the processing container 10. The partition 83 is constructed, for example, by forming a corrosion-resistant film (such as a yttrium oxide film) on the surface of a base material formed of aluminum. A plurality of through holes are formed in the partition 83. An exhaust port 80 is provided below the partition 83 and at the bottom of the processing container 10. The exhaust port 80 is connected to an exhaust device 84 via an exhaust pipe 82. The exhaust device 84 includes a pressure regulating valve and a vacuum pump such as a turbomolecular pump.

[0037] The plasma processing apparatus 1 includes a first high-frequency power supply 48 and a second high-frequency power supply 90. The first high-frequency power supply 48 is a power source that generates first high-frequency electricity. The first high-frequency electricity has a frequency suitable for generating plasma. The frequency of the first high-frequency electricity is, for example, a frequency in the range of 27 MHz to 100 MHz. The first high-frequency power supply 48 is connected to the lower electrode 18 via a matching device 46 and an electrode plate 16. The matching device 46 has circuitry for matching the output impedance of the first high-frequency power supply 48 with the impedance of the load side (lower electrode 18 side). Furthermore, the first high-frequency power supply 48 can also be connected to the upper electrode 34 via the matching device 46.

[0038] The second high-frequency power supply 90 is a power source that generates a second high-frequency power. This second high-frequency power has a frequency lower than that of the first high-frequency power. When the second high-frequency power is used together with the first high-frequency power, it is used as a bias power source for attracting ions to the substrate W. The frequency of the second high-frequency power is, for example, in the range of 400 kHz to 13.56 MHz. The second high-frequency power supply 90 is connected to the lower electrode 18 via a matching adapter 88 and an electrode plate 16. The matching adapter 88 has circuitry for matching the output impedance of the second high-frequency power supply 90 with the impedance of the load side (lower electrode 18 side).

[0039] Alternatively, plasma can be generated using a second high-frequency power source instead of the first high-frequency power source, i.e., using only a single high-frequency power source. In this case, the plasma processing apparatus 1 may not include the first high-frequency power source 48 and the matching device 46, and the frequency of the second high-frequency power source may be a frequency greater than 13.56 MHz, for example, 40 MHz.

[0040] In the plasma processing apparatus 1, gas is supplied from the gas supply unit GS to the plasma processing space for 10 seconds to generate plasma. Additionally, a high-frequency electric field is generated between the upper electrode 34 and the lower electrode 18 by supplying a first high-frequency power and / or a second high-frequency power. Plasma is generated by the generated high-frequency electric field.

[0041] The plasma processing apparatus 1 includes a power supply 50. The power supply 50 is connected to the upper electrode 34. The power supply 50 applies a voltage to the upper electrode 34 to attract positive ions present in the plasma processing space for 10 seconds to the top plate 36.

[0042] The plasma processing apparatus 1 may also include a control unit 200. The control unit 200 is a computer including a control unit 201 (processor, etc.) and a storage unit 202 (memory, etc.). The control unit 201 controls each part of the plasma processing apparatus 1. The storage unit 202 stores control programs and process data. The control unit 201 executes the control program to perform various processes in the plasma processing apparatus 1. The control unit 201 executes the control program and controls each part of the plasma processing apparatus 1 according to the process data.

[0043] Furthermore, the storage unit 202 stores information in Table TB indicating the correlation between the temperature of the edge ring 24 and the HV voltage applied to the edge ring electrode 21. The HV voltage applied to the edge ring electrode 21 needs to be controlled based on the temperature of the edge ring 24 to electrostatically attract the edge ring 24 to the electrostatic chuck 20. For example, when the temperature of the edge ring 24 rises, the HV voltage applied to the edge ring electrode 21 increases, thereby increasing the electrostatic attraction force. Therefore, an appropriate value of the HV voltage required for the edge ring 24 to electrostatically attract to the electrostatic chuck 20 is predetermined based on the temperature of the edge ring 24. Moreover, information obtained from the measurement results indicating the correlation between the temperature of the edge ring 24 and the HV voltage is stored in Table TB. The temperature of the edge ring 24 is measured by a temperature sensor 29 disposed at the bottom of the edge ring 24 and sent to the control device 200. The control unit 201 refers to Table TB stored in the storage unit 202 and controls the HV voltage applied to the edge ring electrode 21 based on the measured temperature of the edge ring 24.

[0044] [Thermal conductive components]

[0045] The thermally conductive member 25 is a sheet-like member disposed between the electrostatic chuck 20 and the edge ring 24. However, the thermally conductive member 25 is not limited to a sheet shape; for example, it can also be a gel-like material.

[0046] The thermally conductive component 25 is a high-dielectric material formed by adding a high-dielectric material to silicon and aluminum oxide (Al2O3). However, silicon carbide or tungsten carbide (WC), which are harder than silicon, can also be used instead of silicon for the thermally conductive component 25. For example, the thermally conductive component 25 can be either a high-dielectric material formed by adding a high-dielectric material to silicon carbide and aluminum oxide (Al2O3), or a high-dielectric material formed by adding a high-dielectric material to tungsten carbide and aluminum oxide (Al2O3).

[0047] The thermally conductive component 25 is non-adhesive. That is, a high dielectric constant and non-adhesive thermally conductive component 25 is disposed between the electrostatic chuck 20 and the edge ring 24 of the plasma processing device 1.

[0048] The heat transfer sheet disposed between the electrostatic chuck 20 and the edge ring 24, transferring heat from the edge ring 24 to the electrostatic chuck 20, has a structure with a high dielectric material on both its upper and lower surfaces and is attached between the electrostatic chuck 20 and the edge ring 24. In this heat transfer sheet, as a method to generate temperature deviations corresponding to the edge ring 24, sometimes the adhesion is improved to stabilize the thermal resistance of the contact interface in a vacuum, or a heat transfer gas is allowed to flow between the electrostatic chuck 20 and the edge ring 24. However, when the adhesion of the heat transfer sheet surface is improved, the heat transfer sheet becomes difficult to peel off from the edge ring 24 and the electrostatic chuck 20 when replacing the heat transfer sheet, resulting in poor maintainability.

[0049] Therefore, the use of a non-adhesive heat transfer sheet was considered to improve maintenance. However, in this case, contact pressure needs to be applied to the thermally conductive member 25 to ensure a tight fit between the heat transfer sheet and the electrostatic chuck 20 and the edge ring 24. For example, when a tight fit is ensured by clamping these members in the middle with clamps, the electrostatic chuck 20 and the edge ring 24 repeatedly undergo thermal expansion and contraction due to heat input from the plasma each time the substrate W is processed, while the heat transfer sheet is clamped by the clamps. This is caused by the difference in linear expansion between the electrostatic chuck 20 and the edge ring 24. As a result, peeling of the heat transfer sheet, relaxation of the clamping force, etc. occur. Therefore, the thermal resistance of the contact interface between the heat transfer sheet and the electrostatic chuck 20 becomes unstable, the thermal resistance of the contact interface between the heat transfer sheet and the edge ring 24 becomes unstable, or deviations occur in the adhesion of the heat transfer sheet and the clamping force during heat transfer sheet installation. As a result, deviations in the thermal resistance of the contact interface of the heat transfer sheet sometimes occur. As a result, a temperature difference is generated between the electrostatic chuck 20 and the heat transfer sheet, and a temperature difference is generated between the edge ring 24 and the heat transfer sheet.

[0050] Therefore, in this embodiment, a thermally conductive member 25 that can stably transfer heat and is easy to maintain is provided. Thus, the thermally conductive member 25 according to this embodiment uses a high-dielectric material, and contact pressure is provided to the thermally conductive member 25 through electrostatic adsorption. Furthermore, the contact interface thermal resistance is controlled by controlling the HV voltage applied to the edge ring electrode 21. Therefore, the contact interface thermal resistance is controlled by flexibly varying the contact pressure on the thermally conductive member 25, thereby enabling the tracking of time-related changes such as wear and tear on the edge ring 24, and allowing for stable control of the temperature of the edge ring 24.

[0051] Figure 2 This is a magnified view of part A of the interface of the thermally conductive member 25, illustrating the polarization of the thermally conductive member 25. In the plasma processing apparatus 1, the edge ring 24 is a component controlled by temperature. A thermally conductive member 25, made of a high-dielectric-constant polymer sheet, is disposed between the edge ring 24 and the electrostatic chuck 20, and an HV voltage is applied to the edge ring electrode 21 within the electrostatic chuck 20. Figure 2 In this process, a positive HV voltage is applied to the edge ring electrode 21. Within the electrostatic chuck 20, negative charges move towards the edge ring electrode 21, resulting in a state where the upper surface of the electrostatic chuck 20 is filled with positive charges. Relative to the positive charges on the upper surface of the electrostatic chuck 20, negative charges are attracted to the lower surface of the thermally conductive member 25, while positive charges move towards the upper surface of the thermally conductive member 25. This polarizes the thermally conductive member 25 through Coulomb force, attracting negative charges to the lower surface of the edge ring 24. Consequently, contact pressure is generated between the upper surface of the electrostatic chuck 20 and the lower surface of the thermally conductive member 25, and between the upper surface of the thermally conductive member 25 and the lower surface of the edge ring 24. The contact pressure between these components can be freely varied by controlling the HV voltage applied to the edge ring electrode 21 under these conditions. Therefore, as schematically shown in portion B, which further enlarges a portion of the interface of the thermally conductive member 25, the interfacial thermal resistance C between the edge ring 24 and the thermally conductive member 25, and between the electrostatic chuck 20 and the thermally conductive member 25 (enlarged portion B shown), can be arbitrarily varied. As a result, the temperature of the edge ring 24 can be maintained and managed at an appropriate temperature.

[0052] Furthermore, by controlling the HV voltage applied to the edge ring electrode 21 to generate the desired Coulomb force, the interfacial thermal resistance between the edge ring 24 and the thermally conductive member 25, as well as the interfacial thermal resistance between the electrostatic chuck 20 and the thermally conductive member 25, is controlled. Therefore, the thermally conductive member 25 does not need to be adhesive. Thus, a thermally conductive member 25 that stably transfers heat and is easy to maintain can be provided.

[0053] [High dielectric constant of thermally conductive components]

[0054] When the thermally conductive component 25 is made of silicon, the dielectric constant ε of silicon is... r It is 6, therefore no heat is generated inside the thermally conductive component 25. Figure 2 The polarization is shown. Therefore, when the thermally conductive component 25 is made of silicon, electrostatic adsorption via the electrostatic chuck 20 is sometimes insufficient.

[0055] Therefore, it is preferable to have a dielectric constant ε of the thermally conductive member 25. r The value is approximately 9. Therefore, the thermally conductive component 25 is formed by adding a high-dielectric material to silicon and aluminum oxide (Al2O3). Examples of high-dielectric materials include titanium oxide and barium titanate fillers.

[0056] However, the thermally conductive component 25 is not limited to this; it can also be made of silicon carbide, which is harder than silicon, containing aluminum oxide (Al2O3) and a high-dielectric material. Alternatively, the thermally conductive component 25 can also be made of tungsten carbide (WC), which is harder than silicon, containing aluminum oxide (Al2O3) and a high-dielectric material.

[0057] [Thickness of thermally conductive components]

[0058] The thickness of the thermally conductive component 25 is preferably 0.5 mm or less. The reason for this is explained.

[0059] Equation (1) represents the electrostatic adsorption force between the edge ring 24 and the thermally conductive member 25. Furthermore, the electrostatic adsorption force is proportional to the contact pressure.

[0060]

Number 1

[0061]

[0062] Here, ε r ε is the dielectric constant of the thermally conductive component 25, ε0 is the dielectric constant of vacuum, V is the HV voltage applied to the edge ring electrode 21, d is the distance from the edge ring electrode 21 to the surface of the edge ring 24 that contacts the mounting stage 14, and S1 is the area of ​​the surface of the edge ring 24 that contacts the mounting stage 14.

[0063] In addition, Equation (2) shows the electrostatic adsorption force between the electrostatic chuck 20 and the thermally conductive member 25.

[0064]

Number 2

[0065]

[0066] Here, d1 is the slot 27 used for the flow path of the heat transfer gas (refer to...). Figure 2 ) is the distance from the edge ring electrode 21, d2 is the depth of the groove, and S2 is the area of ​​the groove.

[0067] When the edge ring 24 is attracted by the electrostatic chuck 20 and a heat transfer gas (such as He gas) is supplied to the groove 27 for cooling, without inserting the thermally conductive member 25 (sheet), an electrostatic attraction force of 291 N is applied based on equations (1) and (2) when the edge ring 24 is peeled off from the electrostatic chuck 20. On the other hand, for example, when a 0.3 mm thermally conductive member 25 is placed between the edge ring 24 and the electrostatic chuck 20, the thickness between the edge ring 24 and the electrostatic chuck 20 is 0.8 mm, and the attraction force decreases to 142 N.

[0068] therefore, Figure 3 The dielectric constant ε of the thermally conductive component 25 was measured. r The result of the adsorption force between the edge ring 24 and the electrostatic chuck 20 when the thickness of the thermally conductive component 25 is changed from 12.5 to 20. Figure 3 This is a diagram illustrating an example of the relationship between the thickness of the thermally conductive member 25 and the adsorption force according to the embodiment. Figure 3 The horizontal axis represents the thickness of the thermally conductive component 25, and the vertical axis represents the adsorption force between the edge ring 24 and the electrostatic chuck 20.

[0069] Figure 3 The result is that when the dielectric constant ε of the thermally conductive component 25 is reduced... r The adsorption force increases when the thermal conductivity is changed from 12.5 to 20. As a result, the adsorption force remains the same compared to the case without the thermally conductive component 25. The dielectric constant ε of the thermally conductive component 25... r The larger the dielectric constant ε of the thermally conductive component 25, the stronger the adsorption force. Therefore, it is possible to increase the dielectric constant ε of the thermally conductive component 25. r To obtain the desired adsorption force in a structure having a thermally conductive member 25, a dielectric constant ε of 20 or higher is required. However, even if the dielectric constant ε of the thermally conductive member 25 is increased... r When the thickness of the thermally conductive member 25 exceeds 0.5 mm, the adsorption force sometimes decreases beyond the allowable range compared to the case without the thermally conductive member 25. Based on the above, when the thickness of the thermally conductive member 25 is greater than 0.5 mm, the electrostatic adsorption force decreases, and even when an HV voltage is applied to the edge ring electrode 21, sufficient electrostatic adsorption sometimes cannot occur between the edge ring 24 and the thermally conductive member 25, or between the electrostatic chuck 20 and the thermally conductive member 25. Therefore, the thickness of the thermally conductive member 25 is preferably 0.5 mm or less.

[0070] In the above description, a slot 27 is provided as a flow path for the heat transfer gas, but slot 27 may not be present. In this case, d1+ε in equation (2) r d2 can be replaced with d. In this case, considering the decrease in adsorption force, it is preferable to make the thickness of the thermally conductive member 25 less than 0.5 mm.

[0071] [Examples of variations of thermally conductive components and electrostatic chucks]

[0072] Reference Figure 4 Here is a simplified explanation of a modified structure of the thermally conductive component 25 and the electrostatic chuck 20. Figure 4 This is a diagram showing a modified example of the structure of the thermally conductive member 25 and the electrostatic chuck 20 according to the embodiment.

[0073] The plasma-exposed portions of the thermally conductive member 25 are preferably coated with a plasma-resistant film 25a. Nickel plating is an example of this plasma-resistant film 25a coating. This protects the plasma-exposed portions of the thermally conductive member 25 from plasma damage. However, at least the upper and lower surfaces of the thermally conductive member 25 are not coated with the plasma-resistant film 25a to maintain the flexibility of the thermally conductive member 25. Figure 4 In this example, the side surfaces of the thermally conductive member 25 are exposed to the plasma, while the upper and lower surfaces of the thermally conductive member 25 are not exposed to the plasma. Therefore, the side surfaces of the thermally conductive member 25 are coated with a plasma-resistant film 25a.

[0074] Due to the heat input from the plasma and the difference in linear expansion between the edge ring 24 and the electrostatic chuck 20, friction sometimes occurs between the edge ring 24 and the thermally conductive member 25, and between the electrostatic chuck 20 and the thermally conductive member 25. In this case, when the upper and lower surfaces of the thermally conductive member 25 are coated with a film 25a, it becomes harder than when no film 25a is applied. Therefore, by coating the upper and lower surfaces of the thermally conductive member 25 with film 25a, the probability of damage to the surfaces of the edge ring 24 and the electrostatic chuck 20 due to friction increases. Therefore, in this embodiment, film 25a is not used to coat at least the upper and lower surfaces of the thermally conductive member 25, but only the portion exposed to the plasma is coated. This maintains the flexibility of the thermally conductive member 25, preventing damage to the edge ring 24 and the electrostatic chuck 20 due to friction.

[0075] exist Figure 1 and Figure 2 In the illustrated embodiment, the edge ring electrode 21 is a single electrode. In contrast, as... Figure 4 As shown in the modified example, the edge ring electrode 21 may also have multiple electrodes 21a, 21b (bipolar). In this case, an HV voltage is applied to the electrodes 21a, 21b to electrostatically attract the edge ring to the electrodes 21a, 21b. The polarity of the HV voltage applied to the electrodes 21a, 21b may be the same or different.

[0076] Alternatively, a refrigerant flow path 120 and / or a heater 121 can be provided in the region of the electrostatic chuck 20 facing the edge ring 24. By combining the thermally conductive member 25 with the refrigerant flow path 120 and / or the heater 121, the temperature of the edge ring 24 can be quickly controlled to a more suitable temperature.

[0077] [Voltage Control Method]

[0078] Next, refer to Figure 5 and Figure 6 This section describes a voltage control method for the edge ring electrode 21 of a plasma processing apparatus 1 that uses the thermally conductive component 25 described above. Figure 5 This is a flowchart illustrating an example of the voltage control method involved in the implementation. Figure 6 This is a diagram used to illustrate the voltage control method involved in the implementation method.

[0079] The voltage control method described in the embodiment is performed by a plasma processing apparatus 1. The plasma processing apparatus 1 includes: an electrostatic chuck 20, which holds a substrate W within a processing container 10 that provides a plasma processing space 10s; an edge ring 24 disposed on the electrostatic chuck 20 in a manner that surrounds the area where the substrate W is held, at least a portion of the edge ring 24 being composed of a conductive member; and an edge ring electrode 21, to which an HV voltage is applied for electrostatically adsorbing the edge ring 24 in a region corresponding to the edge ring 24 inside the electrostatic chuck 20.

[0080] The voltage control method according to the embodiment includes the following steps: processing the substrate W; obtaining the temperature of the edge ring 24; and referring to a storage unit 202 that stores the correlation between the temperature of the edge ring 24 and the HV voltage applied to the edge ring electrode 21, controlling the HV voltage applied to the edge ring electrode 21 based on the obtained temperature of the edge ring 24. The voltage control method according to the embodiment is controlled by a control unit 201. The specific voltage control method will be described below.

[0081] when Figure 5 When the processing begins, the control unit 201 prepares the substrate W (step S1). Next, the control unit 201 applies a set HV voltage to the substrate electrode 20a and the edge ring electrode 21 respectively (step S3). For example, the control unit 201 bases the voltage on the electrode stored in... Figure 1 The information in Table TB showing the relationship between the temperature of the edge ring 24 and the HV voltage will be set to "HV1" when the temperature of the edge ring 24 is "T1". For example, as Figure 6 As shown in (a), at this time point, the HV voltage of HV1 is applied to the edge ring electrode 21.

[0082] Next, the control unit 201 supplies gas from the gas supply unit GS and applies high-frequency voltages from the first high-frequency power supply 48 and the second high-frequency power supply 90 (step S5). However, it is also possible to apply a high-frequency voltage only from the first high-frequency power supply 48.

[0083] Next, the control unit 201 generates plasma from the gas by the high-frequency voltage and processes the substrate W by the generated plasma (step S7). For example, as shown in (b) of Figure 6 , plasma is generated from the gas, and the substrate W is processed by the generated plasma.

[0084] Next, the control unit 201 stops the supply of gas and stops the application of the high-frequency voltage and the HV voltage (step S9). Next, the control unit 201 unloads the processed substrate W (step S11), determines whether there is a next substrate W (step S13), and ends this process when it is determined that there is no next substrate W.

[0085] In step S13, when it is determined that there is a next substrate W, the control unit 201 acquires the temperature of the edge ring 24 measured by the temperature sensor 29 (step S15). Next, the control unit 201 refers to the storage unit 202, and based on the information representing the correlation stored in the table TB, controls the HV voltage applied to the edge ring electrode 21 according to the acquired temperature of the edge ring 24 (step S17). Next, returning to step S1, the control unit 201 prepares the next substrate W and processes the next substrate W by performing the processes after step S3. The control unit 201 repeats this operation until it is determined in step S13 that there is no next substrate.

[0086] For example, when the acquired temperature of the edge ring 24 is "T2", the control unit 201 sets the HV voltage applied to the edge ring electrode 21 to "HV2" based on the information representing the correlation stored in the table TB. For example, as shown in (c) of Figure 6 , the HV voltage of HV2 is applied to the edge ring electrode 21 at this time. At this time, since there is a relationship of HV1 < HV2, the electrostatic adsorption force (Coulomb force) increases, the contact pressure between the edge ring 24 and the heat-conductive member 25 increases, and the contact pressure between the electrostatic chuck 20 and the heat-conductive member 25 increases. As a result, heat transfer is more likely to occur stably between the edge ring 24 and the heat-conductive member 25, and heat transfer is more likely to occur stably between the electrostatic chuck 20 and the heat-conductive member 25, and the temperature of the edge ring 24 can be maintained and managed at a more appropriate temperature. In addition, since the heat-conductive member 25 is non-adhesive, maintenance can be easily performed.

[0087] It should be understood that the thermally conductive components, plasma processing apparatus, and voltage control methods disclosed herein are illustrative and not limiting in all respects. The above-described embodiments can be modified and altered in various ways without departing from the appended claims and their spirit. The matters described in the above embodiments can be adopted in other structures without contradiction, and can also be combined without contradiction.

[0088] The plasma processing apparatus disclosed herein can also be applied to any type of apparatus, including ALD (Atomic Layer Deposition), Capacitively Coupled Plasma (CCP), Inductively Coupled Plasma (ICP), Radial Line Slot Antenna, Electron Cyclotron Resonance Plasma (ECR), and Helicon Wave Plasma (HWP).

Claims

1. A plasma processing apparatus, comprising: an electrostatic chuck; a edge ring disposed above the electrostatic chuck in a manner to surround a region on which a substrate is placed, at least a portion of the edge ring being composed of an electrically conductive member; a polymer sheet having dielectric properties disposed between the electrostatic chuck and the edge ring so as to be in contact with an upper surface of the electrostatic chuck and a lower surface of the edge ring; and an edge ring electrode to which a voltage for electrostatically attracting the edge ring to a region inside the electrostatic chuck corresponding to the edge ring is applied, wherein the polymer sheet has no adhesion, a dielectric constant of the polymer sheet is 20 or more, and a thickness of the polymer sheet is 0.5 mm or less.

2. The plasma processing apparatus according to claim 1, wherein the polymer sheet is formed by adding a high dielectric material to silicon and alumina.

3. The plasma processing apparatus according to claim 2, wherein the high dielectric material is titanium oxide or barium titanate.

4. The plasma processing apparatus according to claim 1, wherein a portion of the polymer sheet exposed to plasma is coated with a film having plasma resistance.

5. The plasma processing apparatus according to claim 1, wherein the edge ring electrode is composed of a plurality of electrodes to which a voltage for electrostatically attracting the edge ring is applied.

6. The plasma processing apparatus according to claim 1, wherein the polymer sheet is formed by adding a high dielectric material to silicon carbide or tungsten carbide and alumina.

7. The plasma processing apparatus according to claim 6, wherein the high dielectric material is titanium oxide or barium titanate.

8. The plasma processing apparatus according to claim 1, wherein a region of the electrostatic chuck facing the edge ring is provided with a refrigerant flow path and / or a heater. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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