Electrostatic chuck, substrate processing apparatus, and substrate processing method

Abstract

[Problem] To accurately control the temperature of a substrate while enabling the substrate to be fixed reliably without bringing other members into contact with the upper surface of the substrate when processing the substrate at a high temperature, for example. [Solution] Provided is an electrostatic chuck for electrostatically attracting a substrate, the electrostatic chuck comprising: a first base material upon which the substrate is placed; and a second base material placed on the lower surface side of the first base material. The first base material comprises a plate member formed from a composite material of metal and ceramics, and an insulating layer formed in layers on the upper surface of the plate member and having insulating properties. The second base material is composed of a material having a thermal expansion coefficient close to that of the composite material.

Description

Electrostatic chuck, substrate processing apparatus, and substrate processing method

[0001] The present disclosure relates to an electrostatic chuck, a substrate processing apparatus, and a substrate processing method.

[0002] In a semiconductor device manufacturing process, a film is formed on a semiconductor wafer (hereinafter referred to as a "wafer"), which is a substrate, by chemical vapor deposition (CVD) or atomic layer deposition (ALD). This film formation process is performed by supplying a film formation gas to a wafer placed on a mounting table in a processing chamber while the wafer is heated to a predetermined temperature by a heater provided on the mounting table. Also known is a film formation apparatus that fixes the wafer to the mounting table by pressing the edge of the wafer on the mounting table with a ring-shaped fixing member during the film formation process (see, for example, Patent Document 1).

[0003] Patent No. 5699425

[0004] The technology disclosed herein allows a substrate to be sufficiently fixed without contacting the top surface of the substrate with other components, for example, when processing the substrate at high temperatures, and also accurately controls the temperature of the substrate.

[0005] One aspect of the technology disclosed herein is an electrostatic chuck that electrostatically attracts a substrate, the electrostatic chuck comprising: a first substrate on whose upper surface the substrate is placed; and a second substrate disposed on the underside of the first substrate, wherein the first substrate comprises a plate-shaped member made of a composite material of metal and ceramics, and an insulating layer formed in a layered form on the upper surface of the plate-shaped member and having insulating properties; and the second substrate is made of a material having a thermal expansion coefficient close to that of the composite material.

[0006] According to the present disclosure, for example, when processing a substrate at high temperatures, the substrate can be sufficiently fixed without other components coming into contact with the top surface of the substrate, and the temperature of the substrate can be accurately controlled.

[0007] Fig. 1 is a schematic cross-sectional view showing an example of a substrate processing apparatus (electrostatic chuck) according to a first embodiment of the technology disclosed herein; Fig. 2 is a schematic enlarged cross-sectional view showing an example of an area [A] surrounded by a two-dot chain line in Fig. 1; Fig. 3 is a schematic enlarged cross-sectional view showing an example of an electrostatic chuck according to a second embodiment of the technology disclosed herein; Fig. 4 is a diagram showing an example of a simulation result of a gas flow; Fig. 5 is a schematic cross-sectional view showing an example of a substrate processing apparatus (electrostatic chuck) according to a third embodiment of the technology disclosed herein;

[0008] As described above, in the technology of Patent Document 1, when a film formation process is performed, the edge of the wafer on the mounting table is pressed down and fixed to the mounting table with a ring-shaped fixing member. However, it is desirable to make the contact area of ​​the wafer with the fixing member as small as possible during the film formation process, and in recent years, it has been desired to fix the wafer to the mounting table without pressing down with a fixing member.

[0009] Furthermore, in the technology of Patent Document 1, only the edge of the wafer is pressed down to the mounting table by a fixing member, and the rest of the wafer is simply placed on the mounting table by the wafer's own weight. Therefore, the wafer and the mounting table may be separated more than expected, which may make it difficult to control the wafer temperature using a heater provided on the mounting table.

[0010] Hereinafter, an embodiment of the technology according to the present disclosure will be described with reference to the drawings. However, the configurations described in the following embodiments are merely examples and are not intended to be limiting. For example, each component included in this configuration can be replaced with any component that can perform the same function. Furthermore, any component may be added.

[0011] First Embodiment A first embodiment will be described below with reference to FIGS. 1 and 2. FIG. 1 is a schematic cross-sectional view showing an example of a substrate processing apparatus (electrostatic chuck) according to a first embodiment of the technology disclosed herein. FIG. 2 is a schematic enlarged cross-sectional view of an area [A] surrounded by a two-dot chain line in FIG. 1. Note that in FIGS. 1 and 2 (as well as FIGS. 3 to 5), the vertical direction (thickness direction, height direction) of the substrate processing apparatus is exaggerated compared to the horizontal direction for ease of understanding, and the ratio between the vertical length and the horizontal length differs from the actual ratio.

[0012] The substrate processing apparatus 100 shown in FIG. 1 is an apparatus for performing a film formation process (substrate processing method) on a semiconductor wafer W (hereinafter referred to as a "wafer W"), which is a substrate, in a semiconductor device manufacturing process. The film formation process is not particularly limited, and a film formation process such as CVD is possible. The CVD process forms a metal film, such as a ruthenium (Ru) film, on the surface of the wafer W. The substrate processing apparatus 100 includes an electrostatic chuck 10 and a processing chamber 20 that houses the electrostatic chuck 10. The electrostatic chuck 10 is a device that electrostatically attracts the wafer W. The processing chamber 20 is an apparatus that performs a film formation process on the wafer W while the wafer W is electrostatically attracted to the electrostatic chuck 10. The interior of the processing chamber 20 is adjusted to a vacuum atmosphere at a desired pressure by a pressure adjustment unit (not shown), and ruthenium is supplied as a processing gas (film formation gas) G1 by a ruthenium supply unit (not shown). Then, by controlling the temperature of the wafer W in this state, a ruthenium film can be formed on the surface of the wafer W. The processing chamber 20 is also earthed.

[0013] 1 , the electrostatic chuck 10 is a laminated body including a first substrate 1 having a disk shape (plate shape) on the upper surface of which a wafer W is placed, and a second substrate 2 having a disk shape (plate shape) on the lower surface of the first substrate 1 and arranged concentrically with the first substrate 1. The electrostatic chuck 10 is supported on a support table 40. In the substrate processing apparatus 100, the electrostatic chuck 10 and the support table 40 form a mounting table 50 on which the wafer W is placed.

[0014] The first substrate 1 includes a plate-shaped member 11 and an insulating layer 12 formed in layers on the upper surface of the plate-shaped member 11. The plate-shaped member 11 is made of a metal-ceramic composite material (MMC: Metal Matrix Composites). This composite material is not particularly limited, and for example, a composite material of aluminum and silicon carbide can be used. The insulating layer 12 is made of an insulating material having insulating properties. This insulating material is not particularly limited, and for example, aluminum oxide (alumina) can be used. An electrode 13 is provided inside the insulating layer 12, i.e., midway through the thickness of the insulating layer 12. The electrode 13 is connected to a DC power source 15 via a conductive wire 14. This applies a voltage to the electrode 13. The negative electrode of the DC power source 15 is preferably grounded. A switch 16 is provided midway through the conductive wire 14. The electrostatic chuck 10 configured as described above is a Johnson-Rahbek type electrostatic chuck and can attract the wafer W by the Johnson-Rahbek force. Specifically, by turning on the switch 16, the wafer W and the electrode 32 function as opposing electrodes of a capacitor, and are polarized across the entire surfaces of the wafer W and the electrode 32, with the insulating layer 12 interposed therebetween. This allows the entire surface of the wafer W, i.e., the entire lower surface (rear surface), to be attracted to the electrostatic chuck 10. Note that the method for forming the insulating layer 12 is not particularly limited, and examples thereof include a method in which the electrode 13 is disposed on the upper surface of the plate-shaped member 11, and aluminum oxide, which is the material for the insulating layer 12, is thermally sprayed onto the upper surface.

[0015] The second substrate 2 is made of a metal material having a thermal expansion coefficient close to that of the composite material constituting the plate-like member 11 of the first substrate 1. This metal material is not particularly limited, and may be, for example, titanium, aluminum oxide, an alloy of copper and tungsten, an alloy of copper and molybdenum, or chromium, but titanium is preferred. For example, when the composite material is made of aluminum and silicon carbide, the thermal expansion coefficient of the composite material constituting the plate-like member 11 is 3×10, depending on the content, i.e., the compounding ratio, of each. －６ ~14 x 10 －６On the other hand, the thermal expansion coefficient of titanium is 8.4 × 10 －６ ~8.6 x 10 －６ [ / °C]. In this embodiment, "the thermal expansion coefficients of the composite material constituting the plate-like member 11 and the metal material constituting the second substrate 2 are close to each other" means that "there is a portion where the thermal expansion coefficient of the composite material and the thermal expansion coefficient of the metal material overlap," but this is not limited to this. In the case of the above-mentioned thermal expansion coefficients, the portion where the thermal expansion coefficient of the composite material and the thermal expansion coefficient of the metal material overlap is 8.4 × 10 －６ ~8.6 x 10 －６ [ / °C]. Titanium is a preferable constituent material of the second substrate 2 because it is relatively readily available. The thickness t2 of the second substrate 2 is thicker than the thickness t11 of the plate-like member 11 of the first substrate 1. The thickness t11 is preferably, for example, 5 mm or more and 20 mm or less, and more preferably 12 mm or more and 15 mm or less. In this case, the thickness t2 is preferably 1.5 times or more and 20 times or less, and more preferably 5 times or more and 10 times or less, of the thickness t11. The number of second substrates 2 arranged in the configuration shown in FIG. 1 is one, but is not limited to this and may be, for example, multiple.

[0016] The first substrate 1 and the second substrate 2 are bonded together via a bonding material 8. The material of the bonding material 8 is not particularly limited, and may be, for example, aluminum. When the bonding material 8 is made of aluminum, an aluminum sheet material serving as the bonding material 8 is interposed between the first substrate 1 and the second substrate 2, and the first substrate 1 and the second substrate 2 are heated while being pressed in a direction that brings them closer together. This melts the aluminum constituting the bonding material 8, bonding the first substrate 1 and the second substrate 2 together. This allows heat from the heating unit 9 provided on the second substrate 2 to be transferred to the wafer W via the first substrate 1 in an appropriate amount when performing a film formation process on the wafer W. Note that, although the first substrate 1 and the second substrate 2 are bonded together via the bonding material 8 in this embodiment, this is not limiting, and the first substrate 1 and the second substrate 2 may be bonded together by, for example, a method using screws or clamping members.

[0017] The second substrate 2 is provided with a heating unit 9 for heating the wafer W. The heating unit 9 is composed of multiple heaters 91 embedded in the second substrate 2. Each heater 91 generates heat when energized. The heaters 91 are distributed horizontally (left and right in FIG. 1 ). The heat generated by each heater 91 is transferred to the wafer W electrostatically attracted to the first substrate 1 via the second substrate 2 and the first substrate 1 in that order. The temperature of the electrostatic chuck 10 (each heater 91) depends on the film formation process, but is preferably 150°C to 250°C, more preferably 150°C to 160°C. In this embodiment, the heaters 91 are embedded in the second substrate 2, but may also be embedded in the plate-like member 11 of the first substrate 1. However, processing for embedding the heaters 91 is easier when processing the second substrate 2 made of a metal material than when processing the plate-like member 11 made of a composite material. Therefore, it is preferable to embed each heater 91 in the second substrate 2 .

[0018] With the electrostatic chuck 10 configured as described above, when a film formation process is performed on a wafer W at a high temperature, the film formation process can be performed while the wafer W is held in close contact with the electrostatic chuck 10 by electrostatic attraction. This eliminates the need for other components, such as an annular clamp ring, that are disposed above a conventional electrostatic chuck and press down to secure the wafer W. Therefore, the electrostatic chuck 10 can sufficiently secure the wafer W without causing the other components to come into contact with the top surface of the wafer W. This allows for stable film formation on the wafer W. Note that, during film formation, it may be desirable to avoid contact between the other components and the top surface of the wafer W. Therefore, electrostatic attraction by the electrostatic chuck 10 is preferable for film formation.

[0019] As described above, the processing chamber 20 is adjusted to a vacuum atmosphere with a desired pressure, and ruthenium, the processing gas G1, is supplied. Then, by controlling the temperature of the wafer W in this state, a ruthenium film can be formed on the surface of the wafer W. Because ruthenium is relatively sensitive to temperature changes, it is preferable to control the temperature of the entire wafer W as accurately as possible during film formation. Therefore, the electrostatic chuck 10 is configured to include a plate-shaped member 11 (first substrate 1) made of a composite material. As a result, when heat from each heater 91 is transferred to the plate-shaped member 11, it is uniformly diffused across the wafer W by the plate-shaped member 11 and then transferred to the wafer W via the insulating layer 12. In this way, the plate-shaped member 11 has a thermal diffusion function that diffuses heat. This allows for accurate temperature control across the entire wafer W during film formation, thereby enabling a uniform ruthenium film to be formed. In this case, the variation in the surface temperature of the wafer W during film formation is typically limited to within ±1°C. Now, consider a case where the plate-shaped member 11 is omitted. In this case, the insulating layer 12 is provided on the second substrate 2. The heat from each heater 91 is not dispersed as uniformly in the second substrate 2 as in the plate-like member 11, and is instead transferred to the wafer W via the insulating layer 12. This type of transfer makes it difficult to accurately control the temperature of the entire wafer W during film formation, and as a result, the ruthenium film may be formed non-uniformly.

[0020] In the electrostatic chuck 10, the first substrate 1 and the second substrate 2 are both thermally deformed by the heat from the heaters 91, but since they have similar thermal expansion coefficients, they tend to undergo similar thermal deformation. This makes it possible to prevent or suppress warping of the electrostatic chuck 10 and maintain the bonded state between the first substrate 1 and the second substrate 2, thereby enabling stable heating of the wafer W on the electrostatic chuck 10. The thermal expansion coefficient of aluminum oxide is 7.0×10 －６ ~7.7 x 10 －６[ / °C]. When the insulating layer 12 is made of aluminum oxide, the insulating layer 12 has a thermal expansion coefficient close to that of the plate-shaped member 11. This allows the insulating layer 12 to maintain its formed state on the plate-shaped member 11 even when heated by the heat from each heater 91, i.e., prevents the insulating layer 12 from peeling off from the plate-shaped member 11 or cracking.

[0021] As shown in FIG. 2 , the electrostatic chuck 10 includes a gas discharge unit (gas discharge system) 5 that discharges a film-formation suppressing gas (gas) G2 that suppresses film formation on a desired portion. In this embodiment, the film-formation suppression targets include the edge W1 of the wafer W and an edge 511 of a first flow control unit 51 of the gas discharge unit 5, which will be described later. The film-formation suppressing gas G2 is not particularly limited, and carbon monoxide (CO) gas, for example, can be used. The gas discharge unit 5 is connected to a gas supply source (not shown) that supplies the film-formation suppressing gas G2. The gas discharge unit 5 includes a first flow control unit (flow control unit) 51 provided on the upper surface of the second substrate 2 and a second flow control unit 52 provided on the side surface of the second substrate 2. The first flow control unit 51 is a flat, annular member disposed concentrically with the second substrate 2. The second flow control unit 52 is an annular member that extends circumferentially along the side surface of the second substrate 2. The first flow control unit 51 and the second flow control unit 52 are components that control the flow of the film formation suppression gas G2. Note that the constituent materials of the first flow control unit 51 and the second flow control unit 52 are not particularly limited, and for example, the same constituent material as the second substrate 2 can be used.

[0022] The gas discharge unit 5 also has a flow path 53 through which the film formation inhibiting gas G2 passes. This flow path 53 is composed of a flow path 531, a flow path 532, a flow path 533, a flow path 534, a flow path 535, and a flow path 536. The flow path 531 is a flow path formed between the second substrate 2 and the support stand 40. The flow path 532 is a flow path that communicates with the flow path 531 and penetrates the second substrate 2 in the vertical direction (thickness direction). The flow path 533 is a flow path that communicates with the flow path 532 and is formed between the first flow control unit 51 and the first substrate 1. The flow path 534 is a flow path that communicates with the flow path 531 and is formed between the second flow control unit 52 and the second substrate 2. The flow path 535 is a flow path that communicates with the flow path 534 and is formed by penetrating the protrusion 521 of the second flow control unit 52 that protrudes toward the second substrate 2 side in the vertical direction (thickness direction). The flow path 536 is connected to the flow path 535 and is formed between the first flow control portion 51 and the second flow control portion 52 .

[0023] The flow path 532 has a first outlet (exhaust port) 532a opening on the upper surface of the second substrate 2. The first outlet 532a discharges the film formation suppressing gas G2 toward the peripheral portion W1 of the wafer W on the first substrate 1 via the flow path 533. This allows the film formation suppressing gas G2 to contact the peripheral portion W1 of the wafer W preferentially over the processing gas G1, thereby preventing or suppressing the processing gas G1 from contacting the peripheral portion W1. As a result, formation of a ruthenium film on the peripheral portion W1 can be suppressed. Note that, because the lower surface (rear surface) of the wafer W is in close contact with the electrostatic chuck 10, formation of a ruthenium film is suppressed. Furthermore, the flow path 533 can control the flow of the film formation suppressing gas G2 discharged from the first outlet 532a. Specifically, the flow path 533 has a relaxation portion 533a on its upstream side that relaxes the flow rate of the film formation suppressing gas G2 and directs the film formation suppressing gas G2 away from the wafer W. The relaxation section 533a is configured as a groove formed in an annular shape on the lower surface of the first flow control section 51. The grooves constituting this relaxation section 533a have a constant depth. By providing such relaxation section 533a, the film formation suppression gas G2 discharged from the first discharge port 532a is sprayed uniformly over as wide an area as possible toward the peripheral portion W1 of the wafer W. This improves the film formation effect of the film formation suppression gas G2 on the peripheral portion W1.

[0024] The flow path 536 also has a second outlet 536a through which the film-formation suppressing gas G2 is discharged toward the edge 511 of the first flow control section 51. This allows the film-formation suppressing gas G2 to contact the edge 511 of the first flow control section 51 preferentially over the processing gas G1, thereby preventing or suppressing the processing gas G1 from contacting the edge 511. As a result, the formation of a ruthenium film on the edge 511 can be suppressed. The film-formation suppressing gas G2 from the second outlet 536a can also suppress the formation of a ruthenium film on the side surface of the second flow control section 52. The second flow control section 52 is configured to be detachable from the second substrate 2, for example, by screwing. This allows the second flow control section 52 to be removed and cleaned to remove the ruthenium film, even if a ruthenium film forms on the side surface of the second flow control section 52. The second flow control section 52 can also be replaced with a new one.

[0025] As shown in FIG. 2 , the gas discharge unit 5 has a ring member 54 concentrically disposed between the protrusion 521 of the second flow control unit 52 and the second substrate 2. The ring member 54 is made of an elastic material, such as various rubber materials or various thermoplastic elastomers, and is disposed in a compressed state between the second flow control unit 52 and the second substrate 2. In this embodiment, the temperature of the support table 40 is controlled to, for example, 80°C, which allows suppression of film formation. The second flow control unit 52 is configured to be detachable from the support table 40, for example, by screw fastening. The temperature of the second flow control unit 52 is also controlled to 80°C, similar to the temperature of the support table 40. In contrast, the temperature of the electrostatic chuck 10 is controlled to, for example, 155°C. The ring member 54, together with the flow paths 531 and 534, can prevent heat from the electrostatic chuck 10 from being lost to the second flow control unit 52 or the support table 40. This allows the temperature of the electrostatic chuck 10 to be stably maintained at 155°C. In this way, the ring member 54 is a member that exhibits a heat insulating function together with the flow paths 531 and 534 .

[0026] Although not shown, the electrostatic chuck 10 is provided with a coolant flow path through which a coolant passes, a thermocouple for detecting the temperature of the electrostatic chuck 10, and the like. Also, although not shown, the electrostatic chuck 10 is provided with a plurality of lift pins that are supported so as to be capable of retracting from, i.e., being raised and lowered relative to, the electrostatic chuck 10. When a wafer W is loaded into the processing chamber 20, the wafer W can be supported on the lift pins that protrude from the surface of the electrostatic chuck 10. The lift pins then descend while supporting the wafer W, allowing a film deposition process to be performed on the wafer W on the electrostatic chuck 10. Furthermore, when the wafer W is to be unloaded from the processing chamber 20 after the film deposition process, the lift pins again protrude from the surface of the electrostatic chuck 10, so that the wafer W is supported on the lift pins. The wafer W can then be unloaded in this state.

[0027] Second Embodiment A second embodiment will be described below with reference to FIGS. 3 and 4. Differences from the previous embodiment will be mainly described, and similar points will not be described again. This embodiment is similar to the first embodiment except for the configuration (shape) of the flow path of the gas exhaust section. FIG. 3 is a schematic enlarged cross-sectional view showing an example of an electrostatic chuck according to a second embodiment of the technology disclosed herein. FIG. 3(b) is an enlarged view of the area [B] surrounded by the two-dot chain line in FIG. 3(a). FIG. 4 is a diagram showing an example of a simulation result of a gas flow.

[0028] As shown in FIG. 3A , in this embodiment, the gas discharge unit 5 has a flow path 55 through which the film formation inhibiting gas G2 passes. The flow path 55 is composed of a flow path 551, a flow path 552, a flow path 553, a flow path 554, and a flow path 555. The flow path 551 is a flow path formed between the second substrate 2 and the support table 40 and has a function similar to that of the flow path 531 of the flow path 53 in the first embodiment. The flow path 552 is connected to the flow path 551 and is a flow path formed between the second flow control unit 52 and the second substrate 2 and has a function similar to that of the flow path 534 of the flow path 53 in the first embodiment. The flow path 553 is connected to the flow path 552 and is a flow path formed between the first flow control unit 51 and the second substrate 2. The flow path 554 is connected to the flow path 553 and is a flow path formed between the first flow control unit 51 and the first substrate 1 and has a function similar to that of the flow path 533 of the flow path 53 in the first embodiment. The flow path 555 is connected to the flow path 552 and is formed between the first flow control section 51 and the second flow control section 52, and has the same function as the flow path 536 of the flow path 53 in the first embodiment.

[0029] As shown in FIG. 3B , the flow path 554 includes a relaxation section 554a downstream thereof that relaxes the flow velocity of the film formation suppression gas G2 and directs the film formation suppression gas G2 away from the wafer W. The relaxation section 554a is configured as a circular groove formed on the upper surface of the first flow control section 51. The depth of the groove constituting the relaxation section 554a varies in two stages (stepwise). The depth DP1 of the deepest portion is preferably 1.5 mm to 3.0 mm, and more preferably 1.5 mm to 2.0 mm. The depth DP2 of the shallowest portion is preferably 0.8 mm to 1.5 mm, and more preferably 0.8 mm to 1.2 mm. A gap GP is formed between the shallowest portion and the wafer W, and the size GP of the gap is preferably 0.2 mm to 0.5 mm, and more preferably 0.2 mm to 0.3 mm. The width WD1 of the deepest portion is preferably 1 mm to 2 mm, more preferably 1 mm to 1.5 mm. The distance WD2 from the sidewall of the relaxation portion 554a to the edge W1 of the wafer W is preferably 0.5 mm to 5 mm, more preferably 1 mm to 3 mm. The bottom of the deepest portion is rounded, and the radius R is preferably 0.2 mm to 0.5 mm, more preferably 0.4 mm to 0.5 mm.

[0030] 4 shows an example of the simulation results of the gas flow in the relaxation section 554a and its periphery. The gas contains the process gas G1 and the film formation suppression gas G2. As shown in FIG. 4, it can be seen that the gas flows in a direction away from the wafer W around the upper periphery of the wafer W. This confirms that the relaxation section 554a is effective in preventing film formation on the peripheral portion W1 of the wafer W.

[0031] Third Embodiment A third embodiment will be described below with reference to Fig. 5. The description will focus on differences from the previous embodiments, and descriptions of similar points will be omitted. This embodiment is similar to the first embodiment except for the layered structure of the electrostatic chuck. Fig. 5 is a schematic cross-sectional view showing an example of a substrate processing apparatus (electrostatic chuck) according to a third embodiment of the technology disclosed herein.

[0032] As shown in FIG. 5 , in this embodiment, the electrostatic chuck 10 includes a first substrate 1 and a second substrate 2, and further includes a third substrate 3 and a fourth substrate 4 stacked together. The third substrate 3 is plate-shaped and disposed on the underside of the second substrate 2. The third substrate 3 is made of the same composite material as the plate-shaped member 11. The fourth substrate 4 is plate-shaped and disposed on the underside of the third substrate 3. The fourth substrate 4 is made of the same metal material as the second substrate 2, i.e., a metal material having a thermal expansion coefficient close to that of the composite material constituting the plate-shaped member 11. Furthermore, the second substrate 2 and the third substrate 3 and the third substrate 3 and the fourth substrate 4 can be bonded using an aluminum bonding material, as in the case of the first substrate 1 and the second substrate 2. This layered structure reduces the thermal expansion difference between the first substrate 1 to the fourth substrate 4 even when they are thermally deformed, thereby preventing or suppressing warping of the electrostatic chuck 10. This allows stable heating of the wafer W on the electrostatic chuck 10. Regarding the relationship in thickness between the substrates, in the configuration shown in Fig. 5, the thickness t11 of the plate-like member 11 is equal to the thickness t3 of the third substrate 3, and the thickness t2 of the second substrate 2 is equal to the thickness t4 of the fourth substrate 4, but this is not limiting.

[0033] Although the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the present disclosure.

[0034] This application claims priority based on Japanese Patent Application No. 2023-185753, filed on October 30, 2023, the entire contents of which are incorporated herein by reference.

[0035] REFERENCE SIGNS LIST 1 First substrate 11 Plate-shaped member 12 Insulating layer 2 Second substrate 10 Electrostatic chuck 20 Processing chamber 100 Substrate processing apparatus W Wafer

Claims

1. An electrostatic chuck for electrostatically attracting a substrate, comprising: a first base material on which the substrate is placed; and a second base material arranged on the underside of the first base material, wherein the first base material comprises a plate-shaped member made of a composite material of metal and ceramics, and an insulating layer having insulating properties and formed in a layered form on the upper surface of the plate-shaped member, and the second base material is made of a material having a thermal expansion coefficient close to that of the composite material.

2. The electrostatic chuck of claim 1, wherein said composite material is an aluminum and silicon carbide composite material.

3. The electrostatic chuck of claim 1, wherein said second substrate is comprised of any one of titanium, an alloy of copper and tungsten, an alloy of copper and molybdenum, and chromium.

4. The electrostatic chuck according to claim 1, wherein the first base material and the second base material are bonded together via a bonding material.

5. The electrostatic chuck of claim 4, wherein said bonding material is comprised of aluminum.

6. The electrostatic chuck of claim 1, wherein said insulating layer is comprised of aluminum oxide.

7. The electrostatic chuck according to claim 1, wherein an electrode to which a voltage is applied when electrostatically attracting the substrate is provided inside said insulating layer.

8. The electrostatic chuck of claim 1, further comprising a gas exhaust portion having an exhaust port for exhausting gas to an edge of the substrate on the first base material.

9. An electrostatic chuck as described in claim 8, wherein the exhaust port is provided so as to open onto an upper surface of the second substrate, and the gas exhaust section is provided on the upper surface of the second substrate and has a flow control section which controls the flow of the gas exhausted from the exhaust port.

10. The electrostatic chuck of claim 9, wherein the flow control section forms a flow path through which the gas passes between the first base material and the flow path, and the flow path has a relaxation section on the upstream or downstream side thereof that relaxes the flow rate of the gas and directs the gas in a direction away from the substrate.

11. The electrostatic chuck of claim 9, wherein the gas exhaust portion has a second exhaust port that exhausts the gas to an edge of the flow control portion when the exhaust port is a first exhaust port.

12. An electrostatic chuck as described in claim 1, comprising: a third substrate arranged on the underside of the second substrate; and a fourth substrate arranged on the underside of the third substrate, wherein the third substrate is made of the composite material, and the fourth substrate is made of a material having a thermal expansion coefficient close to that of the composite material.

13. The electrostatic chuck according to claim 1, further comprising a heating portion provided on the second base material for heating the substrate.

14. The electrostatic chuck according to claim 1, which is used during deposition of a ruthenium film on the substrate.

15. A substrate processing apparatus comprising: an electrostatic chuck for electrostatically attracting a substrate; and a processing chamber in which the electrostatic chuck is housed and in which a film formation process is performed on the substrate while the substrate is electrostatically attracted to the electrostatic chuck, wherein the electrostatic chuck comprises: a first base material on which the substrate is placed; and a second base material arranged on the underside of the first base material, the first base material comprising a plate-shaped member made of a composite material of metal and ceramics, and a conductive layer having electrical conductivity and formed in a layered form on the upper surface of the plate-shaped member, and the second base material is made of a material having a thermal expansion coefficient close to that of the composite material.

16. A substrate processing method for performing a film formation process on a substrate, wherein the substrate is electrostatically attracted to an electrostatic chuck when the film formation process is performed on the substrate, the electrostatic chuck comprising: a first base material on which the substrate is placed; and a second base material arranged on the underside of the first base material, the first base material comprising: a plate-shaped member made of a composite material of metal and ceramics; and an insulating layer having insulating properties, formed in a layered manner on the upper surface of the plate-shaped member, and the second base material being made of a material having a thermal expansion coefficient close to that of the composite material.

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