JP6882040B2 - Holding device - Google Patents

Description

The techniques disclosed herein relate to holding devices that hold objects.

For example, in a semiconductor manufacturing apparatus, an electrostatic chuck is used as a holding apparatus for holding a semiconductor wafer. The electrostatic chuck includes, for example, a plate-shaped ceramic layer and an internal electrode provided inside the ceramic layer, and utilizes the electrostatic attraction generated by applying a voltage to the internal electrode. A semiconductor wafer is attracted and held on the surface of the ceramic layer (hereinafter referred to as "adsorption surface").

If the temperature distribution of the semiconductor wafer held by the electrostatic chuck becomes non-uniform, the accuracy of each process (deposition, etching, exposure, etc.) on the semiconductor wafer decreases. Therefore, the temperature distribution of the semiconductor wafer is applied to the electrostatic chuck. Performance to make it uniform is required. Therefore, the electrostatic chuck is provided with a heater layer having a conductive resistance heating element, and the temperature of the adsorption surface of the ceramic layer is controlled by heating by the heater layer.

In such an electrostatic chuck, an anisotropic heat transfer body such as a graphite sheet is provided between the ceramic layer and the heater layer in order to suppress temperature unevenness in the surface direction on the adsorption surface of the ceramic layer. An electrostatic chuck provided is known (see, for example, Patent Document 1). The anisotropic heat transfer body is arranged so that the heat transfer coefficient in the plane direction orthogonal to the first direction is higher than the heat transfer coefficient in the first direction substantially orthogonal to the adsorption surface of the ceramic layer. .. As a result, temperature unevenness in the surface direction on the suction surface can be suppressed. Further, for example, in order to suppress the release of foreign matter (for example, carbon contained in the anisotropic heat transfer body) from the anisotropic heat transfer body, a film is formed so as to cover the surface of the anisotropic heat transfer body. There is.

International Publication No. 2015/1989942

In a conventional holding device including an anisotropic heat transfer body on which a film is formed, a film is simply formed on the surface of the anisotropic heat transfer body. Therefore, for example, an anisotropic heat transfer body and a film are used. There is a problem that the coating is easily peeled off from the surface of the anisotropic heat transfer body due to the stress generated due to the difference in the coefficient of thermal expansion.

It should be noted that such a problem is not limited to the electrostatic chuck, but is a common problem not only in the holding device for holding the object on the surface of the ceramic layer, such as a vacuum chuck and a heating device.

This specification discloses a technique capable of solving the above-mentioned problems.

(1) The holding device disclosed in the present specification has a first surface substantially orthogonal to the first direction and a second surface opposite to the first surface, and is made of ceramics. The formed ceramic layer, a heater layer arranged inside the ceramic layer or on the second surface side of the ceramic layer and having a resistance heating element, the first surface of the ceramic layer, and the heater. A heat transfer layer arranged at at least one of a position between the layers and a position opposite to the first surface of the ceramics layer with respect to the heater layer, in the first direction. The first of the ceramics layers includes a heat transfer layer including an anisotropic heat transfer body arranged so that the heat transfer coefficient in the plane direction orthogonal to the first direction is higher than the heat transfer coefficient. In a holding device for holding an object on the surface of the anisotropy, the anisotropic heat transfer body is provided with a third surface on one side of the anisotropic heat transfer body in the first direction to a fourth surface on the other side. A first through hole is formed that penetrates to the surface of the heat transfer layer, and the heat transfer layer further includes a coating film and a connecting portion, and the coating film is the third surface of the anisotropic heat transfer body. And the first cover portion coated on the third surface so as to close the opening of the first through hole formed on the third surface, and the anisotropic heat transfer body. Includes a second cover portion that covers the fourth surface and is coated on the fourth surface so as to close the opening of the first through hole formed on the fourth surface. The connecting portion is located in the first through hole, and is characterized in that the first cover portion and the second cover portion are connected to each other. According to this holding device, the anisotropic heat transfer body is formed with a first through hole penetrating from the third surface to the fourth surface in the first direction. The coating includes a first cover portion and a second cover portion. The first cover portion covers the third surface of the anisotropic heat transfer body and is covered with the third surface so as to close the opening of the first through hole formed on the third surface. There is. The second cover portion covers the fourth surface of the anisotropic heat transfer body and is covered with the fourth surface so as to close the opening of the first through hole formed on the fourth surface. There is. The connecting portion is located in the first through hole and connects the first cover portion and the second cover portion. As a result, it is possible to prevent the coating film from peeling off from the anisotropic heat transfer body, as compared with the conventional holding device in which the coating film is simply coated on the surface of the anisotropic heat transfer body.

(2) In the holding device, the anisotropic heat transfer body further penetrates from the third surface to the fourth surface, and has a second through hole having an inner diameter larger than that of the first through hole. Is formed, and each of the first cover portion and the second cover portion is formed with a communication hole that communicates through the second through hole. Good. According to this holding device, the first surface is formed by forming a singular point of temperature distribution in the first through hole as compared with the case where the inner diameter of the first through hole is larger than the inner diameter of the second through hole. It is possible to suppress the occurrence of temperature unevenness.

(3) In the holding device, the anisotropic heat transfer body is formed with a plurality of the first through holes, and the plurality of first through holes are substantially mutual in the first directional view. It may be configured to be arranged at equal intervals. According to this holding device, it is possible to suppress the occurrence of temperature unevenness on the first surface due to the variation in the arrangement of the first through holes.

(4) In the holding device, the connecting portion may include a material having a heat transfer coefficient lower than that of the coating film. According to this holding device, the first through hole is formed with a singular point of temperature distribution, as compared with the case where the connecting portion is made of a material having a heat transfer coefficient equal to or higher than that of the coating. It is possible to suppress the occurrence of temperature unevenness on the surface.

(5) In the holding device, the connecting portion and the coating film may be formed of the same material. According to this holding device, the connecting force between the first cover portion and the second cover portion can be improved as compared with the configuration in which the connecting portion and the coating film are made of different materials.

The techniques disclosed in the present specification can be realized in various forms, for example, in the form of a holding device, an electrostatic chuck, a heater, a vacuum chuck, a manufacturing method thereof, and the like. It is possible.

It is a perspective view which shows schematic appearance structure of the electrostatic chuck 100 in this embodiment. It is explanatory drawing which shows typically the XZ cross-sectional structure of the electrostatic chuck 100 in this embodiment. It is explanatory drawing which shows typically the XY cross-sectional structure of the electrostatic chuck 100 in this embodiment. It is explanatory drawing which shows schematic the XZ cross-sectional structure which enlarged X1 part of FIG. It is explanatory drawing which shows schematic the XZ cross-sectional structure which enlarged X2 part of FIG. It is explanatory drawing which shows the manufacturing process of a heat transfer layer 60.

A. Embodiment:
A-1. Configuration of electrostatic chuck 100:
FIG. 1 is a perspective view schematically showing an external configuration of the electrostatic chuck 100 in the present embodiment, and FIG. 2 is an explanatory view schematically showing an XZ cross-sectional configuration of the electrostatic chuck 100 in the present embodiment. FIG. 3 is an explanatory view schematically showing an XY cross-sectional configuration of the electrostatic chuck 100 according to the present embodiment. FIG. 2 shows the XY cross-sectional configuration of the electrostatic chuck 100 at the position II-II of FIG. 3, and FIG. 3 shows the XY cross-sectional configuration of the electrostatic chuck 100 at the position III-III of FIG. It is shown. Each figure shows XYZ axes that are orthogonal to each other to identify the direction. In the present specification, for convenience, the Z-axis positive direction is referred to as an upward direction, and the Z-axis negative direction is referred to as a downward direction, but the electrostatic chuck 100 is actually installed in a direction different from such a direction. May be done.

The electrostatic chuck 100 is a device that attracts and holds an object (for example, a semiconductor wafer W) by electrostatic attraction, and is used, for example, for fixing a semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing apparatus. The electrostatic chuck 100 includes a holding plate 10 and a base plate 20 arranged side by side in a predetermined arrangement direction (in the present embodiment, the vertical direction (Z-axis direction)). The holding plate 10 and the base plate 20 are arranged such that the lower surface of the holding plate 10 (hereinafter referred to as “ceramic side joint surface S2”) and the upper surface of the base plate 20 (hereinafter referred to as “base side joint surface S3”) are arranged in the above-mentioned arrangement direction. It is arranged so as to face the. The electrostatic chuck 100 further includes a bonding layer 30 arranged between the ceramic side bonding surface S2 of the holding plate 10 and the base side bonding surface S3 of the base plate 20. The electrostatic chuck 100 corresponds to the holding device in the claims, and the arrangement direction corresponds to the first direction in the claims.

The holding plate 10 is, for example, a circular flat plate-shaped member, the diameter of the holding plate 10 is, for example, about 50 (mm) to 500 (mm), and the thickness of the holding plate 10 is, for example, 1 (mm) to 1 (mm). It is about 10 (mm). The holding plate 10 includes a ceramic layer 12, a heater layer 50, and a heat transfer layer 60 arranged between the ceramic layer 12 and the heater layer 50.

The ceramic layer 12 is, for example, a circular flat sheet and is made of ceramics. Various ceramics can be used as the material for forming the ceramic layer 12, and from the viewpoints of strength, abrasion resistance, plasma resistance, etc., for example, aluminum oxide (alumina, Al ₂ O ₃ ) or aluminum nitride (Al N). It is preferable that ceramics containing the above as the main component are used. The main component referred to here means the component having the highest content ratio (weight ratio).

Inside the holding plate 10, a pair of internal electrodes 40 formed of a conductive material (for example, tungsten, molybdenum, etc.) are provided. When a voltage is applied to the pair of internal electrodes 40 from a power source (not shown), an electrostatic attraction is generated, and the semiconductor wafer W is referred to as an upper surface of the holding plate 10 (hereinafter referred to as “adsorption surface S1”) by this electrostatic attraction. ) Is adsorbed and fixed. The suction surface S1 of the holding plate 10 corresponds to the first surface in the claims, and the lower surface S4 of the holding plate 10 opposite to the suction surface S1 corresponds to the second surface in the claims. ..

The heater layer 50 has, for example, a circular flat sheet shape, and is made of ceramics like the ceramic layer 12. Inside the heater layer 50, a heater 52 made of a resistance heating element formed of a conductive material (for example, tungsten, molybdenum, etc.) is provided. The heaters 52 are arranged substantially concentrically in the Z direction, for example, in order to heat the suction surface S1 as evenly as possible. When a voltage is applied to the heater 52 from a power source (not shown), the heater 52 generates heat to heat the holding plate 10, and the semiconductor wafer W held on the suction surface S1 of the holding plate 10 is heated. Thereby, the temperature control of the semiconductor wafer W is realized. The configuration of the heat transfer layer 60 will be described later.

The base plate 20 is, for example, a circular flat plate-like member having the same diameter as the holding plate 10 or having a diameter larger than that of the holding plate 10, and is formed of, for example, a metal (aluminum, an aluminum alloy, etc.). The diameter of the base plate 20 is, for example, about 220 (mm) to 550 (mm), and the thickness of the base plate 20 is, for example, about 20 (mm) to 40 (mm).

A refrigerant flow path 21 is formed inside the base plate 20. When a refrigerant (for example, fluorinated liquid, water, etc.) is flowed through the refrigerant flow path 21, the base plate 20 is cooled, and the holding plate is transferred by heat transfer between the base plate 20 and the holding plate 10 via the bonding layer 30. 10 is cooled, and the semiconductor wafer W held on the suction surface S1 of the holding plate 10 is cooled. Thereby, the temperature control of the semiconductor wafer W is realized.

The bonding layer 30 contains an adhesive such as a silicone resin, an acrylic resin, or an epoxy resin, and bonds the holding plate 10 and the base plate 20. The thickness of the bonding layer 30 is, for example, about 0.1 (mm) to 1 (mm).

Further, the electrostatic chuck 100 is formed with a plurality of (three in this embodiment) pin insertion holes 14 extending in the vertical direction from the base plate 20 to the suction surface S1 of the holding plate 10. The pin insertion hole 14 is a hole for movably inserting a lift pin (not shown) for pushing up the semiconductor wafer W arranged on the holding plate 10 and separating it from the suction surface S1 of the holding plate 10.

A-2. Detailed configuration of heat transfer layer 60:
FIG. 4 is an explanatory view schematically showing an enlarged XZ cross-sectional structure of the X1 portion of FIG. 2, and FIG. 5 is an explanatory view schematically showing an enlarged XZ cross-sectional structure of the X2 portion of FIG. The heat transfer layer 60 includes a graphite sheet 70, a metal film 80, and a connecting portion 90. The graphite sheet 70 has, for example, a circular flat sheet and is made of graphite. Further, in the graphite sheet 70, the heat transfer coefficient in the plane direction (XY plane direction) orthogonal to the vertical direction is higher than the heat transfer coefficient in the arrangement direction (Z-axis direction) substantially orthogonal to the adsorption surface S1 of the ceramic layer 12. It is arranged so that it is high.

As shown in FIGS. 2 and 3, the graphite sheet 70 is formed with a first through hole 72. The first through hole 72 is a hole that penetrates in the vertical direction from the graphite upper surface 70A, which is the surface of the graphite sheet 70 on one side in the vertical direction, to the graphite lower surface 70B, which is the surface on the other side. In the present embodiment, a plurality of first through holes 72 are formed in the graphite sheet 70, and these plurality of first through holes 72 are the positions where the pin insertion holes 14 described below are formed in a vertical view. Regardless of, they are arranged at approximately equal intervals. Specifically, the plurality of first through holes 72 are arranged at substantially equal intervals in the radial direction of the graphite sheet 70, and are arranged at substantially equal intervals in the circumferential direction of the graphite sheet 70.

Further, the graphite sheet 70 is formed with a second through hole 74. The second through hole 74 is a hole that penetrates vertically from the graphite upper surface 70A to the graphite lower surface 70B. As shown in FIGS. 4 and 5, the inner diameter D2 of the second through hole 74 is larger than the inner diameter D1 of the first through hole 72. The inner diameter D1 of the first through hole 72 is preferably larger than 0.5 (mm) and smaller than 3 (mm). The inner diameter D2 of the second through hole 74 is preferably larger than 1.5 (mm) and smaller than 15 (mm). The ratio of the depth in the vertical direction (= depth / inner diameter) to the inner diameter of each of the through holes 72 and 74 is preferably 0.5 or more and 30 or less. However, the shape of each of the through holes 72 and 74 is not limited to a circular shape, and may be, for example, an elliptical shape. The graphite sheet 70 corresponds to an anisotropic heat transfer body within the scope of claims. Further, the graphite upper surface 70A corresponds to the third surface in the claims, and the graphite lower surface 70B corresponds to the fourth surface in the claims.

The metal film 80 is formed of a metal such as aluminum or titanium. The metal film 80 includes an upper cover portion 82, a lower cover portion 84, an outer cover portion 86, and an inner cover portion 88. The upper cover portion 82 covers the entire graphite upper surface 70A of the graphite sheet 70, and is coated (formed) on the graphite upper surface 70A so as to close the upper opening of each first through hole 72. Further, in the upper cover portion 82, a first communication hole 82A is formed at a position corresponding to the second through hole 74 (see FIG. 5). The lower cover portion 84 covers the entire graphite lower surface 70B of the graphite sheet 70, and is covered with the graphite lower surface 70B so as to close the lower opening of each first through hole 72. Further, in the lower cover portion 84, a second communication hole 84A is formed at a position corresponding to the second through hole 74 (see FIG. 5). That is, the first communication hole 82A and the second communication hole 84A communicate with each other through the second through hole 74. The outer cover portion 86 covers the outer circumference of the graphite sheet 70 over the entire circumference, and is connected to the peripheral edge of the upper cover portion 82 and the peripheral edge of the lower cover portion 84 over the entire circumference. The inner cover portion 88 has a substantially cylindrical shape, covers the inner peripheral wall constituting each of the second through holes 74 over the entire circumference, and is connected to the upper cover portion 82 and the lower cover portion 84 over the entire circumference. That is, the entire surface of the graphite sheet 70 exposed to the outside is covered with the metal film 80. The first communication hole 82A and the second communication hole 84A correspond to the communication holes within the scope of the claims.

Since the graphite sheet 70 is covered with the metal film 80 in this way, it is possible to prevent foreign substances (for example, carbon) contained in the graphite sheet 70 from diffusing and adhering to the semiconductor wafer W, for example. Further, the entire surface of the graphite sheet 70 is covered with the metal film 80. Therefore, the diffusion of foreign matter can be suppressed more effectively. Further, as compared with the configuration in which a part of the surface of the graphite sheet 70 is not covered with the metal film 80, it is possible to more effectively suppress the peeling of the metal film 80 from the graphite sheet 70. Further, the graphite sheet 70 has low bondability with other members (for example, the ceramic layer 12, the heater layer 50, and the base plate 20). On the other hand, in the present embodiment, since the graphite sheet 70 is bonded to another member via the metal film 80, the bonding strength with the other member can be improved. The thickness of the metal film 80 is, for example, 50 (μm) or more and 300 (μm) or less. The metal film 80 corresponds to the coating in the claims, the upper cover portion 82 corresponds to the first cover portion in the claims, and the lower cover portion 84 corresponds to the second cover in the claims. Corresponds to the part.

The connecting portion 90 is located in each of the first through holes 72, and has an upper cover portion 82 that covers the upper opening of each first through hole 72 and a lower cover that covers the lower opening of each first through hole 72. It is connected to the portion 84. The connecting portion 90 is formed of the same metal as the metal film 80, and is integrally formed with the metal film 80.

A-3. Manufacturing method of electrostatic chuck 100:
Next, a method of manufacturing the electrostatic chuck 100 in this embodiment will be described. FIG. 6 is an explanatory diagram showing a manufacturing process of the heat transfer layer 60.

First, for example, a plurality of ceramic green sheets containing alumina as a main component are prepared, and each ceramic green sheet is subjected to necessary processing such as application of electrode ink for forming the internal electrode 40. As the electrode ink, for example, a metallized ink obtained by mixing tungsten powder with a raw material powder for a ceramic green sheet containing alumina as a main component to form a slurry is used. Next, the metallized paste, which is a material for forming the heater 52, is uniformly applied onto one ceramic green sheet using a coating machine or the like. The metallized paste is produced, for example, by adding a conductive powder such as tungsten or molybdenum to a mixture of aluminum nitride powder, an acrylic binder, and an organic solvent and kneading the paste. Next, a plurality of ceramic green sheets including the ceramic green sheet coated with the electrode ink are laminated and thermocompression bonded to prepare the ceramic layer 12 before sintering. Further, the heater layer 50 before sintering is produced by laminating a plurality of ceramic green sheets including the ceramic green sheet coated with the metallized paste and thermocompression bonding.

The heat transfer layer 60 is produced as follows. As shown in FIG. 6, first, a graphite sheet 70 in which the first through hole 72 and the second through hole 74 are formed is prepared (S110). Next, by thermal spraying, a metal film is formed on the entire surface of the graphite sheet 70, and the entire space in each of the first through holes 72 and each of the second through holes 74 is filled with metal (S120). ). Next, a hole to be a pin insertion hole 14 is formed in each of the second through holes 74 filled with metal (S130). As a result, the heat transfer layer 60 is produced.

Next, the ceramic layer 12 before sintering and the heater layer 50 before sintering are each fired in a reducing atmosphere (for example, firing at 1400 to 1800 ° C. for 5 hours). After that, the heat transfer layer 60 is arranged between the ceramic layer 12 after sintering and the heater layer 50 after sintering, and the ceramic layer 12 and the heat transfer layer 60 are joined via an adhesive, and the heat transfer layer is formed. The 60 and the heater layer 50 are joined via an adhesive. Thereby, the holding plate 10 can be manufactured. In particular, since the difference between the coefficient of thermal expansion of the ceramic layer 12 and the coefficient of thermal expansion of the heat transfer layer 60 is large, the coefficient of thermal expansion of the adhesive is the coefficient of thermal expansion of the ceramic layer 12 and the coefficient of thermal expansion of the heat transfer layer 60. The value is preferably between the coefficient and the coefficient, and the adhesive is preferably formed of an elastically deformable (flexible) resin material or the like having a function as a cushioning material.

Next, the holding plate 10 and the base plate 20 are joined to each other by using an adhesive such as a silicone resin, an acrylic resin, or an epoxy resin. As a result, the production of the electrostatic chuck 100 having the above-described configuration is completed.

A-4. Effect of this embodiment:
As described above, according to the electrostatic chuck 100 of the present embodiment, the graphite sheet 70 is formed with the first through hole 72. The metal film 80 includes an upper cover portion 82 and a lower cover portion 84. The upper cover portion 82 covers the graphite upper surface 70A of the graphite sheet 70, and is covered with the graphite upper surface 70A so as to close the opening of the first through hole 72 formed in the graphite upper surface 70A. The lower cover portion 84 covers the graphite lower surface 70B of the graphite sheet 70, and is covered with the graphite lower surface 70B so as to close the opening of the first through hole 72 formed in the graphite lower surface 70B. The connecting portion 90 is located in the first through hole 72 and connects the upper cover portion 82 and the lower cover portion 84. That is, by connecting the upper cover portion 82 and the lower cover portion 84 via the connecting portion 90, the upper cover portion 82 is suppressed from being separated from the graphite upper surface 70A, and the lower cover portion 84 is the graphite lower surface. Separation from 70B is suppressed. As a result, it is possible to prevent the metal film 80 from peeling off from the graphite sheet 70, as compared with a conventional holding device in which a film is simply formed on the surface of the anisotropic heat transfer body.

Further, if a hole that penetrates the metal film 80 vertically is formed at a position corresponding to the first through hole 72 of the graphite sheet 70, an opening of the first through hole 72 of the graphite sheet 70 is formed. Stress is concentrated on the edges, and for example, the metal film 80 may be easily peeled off. On the other hand, as shown in FIG. 4, in the present embodiment, the upper cover portion 82 and the lower cover portion 84 are connected by the connecting portion 90 via the first through hole 72, and the upper cover portion is connected. The 82 and the lower cover portion 84 are respectively arranged so as to close the opening of the first through hole 22. Therefore, a first force F1 that pulls the metal film 80 toward the outer peripheral side of the opening of the first through hole 72, a second force F2 that pulls the metal film 80 into the first through hole 72, and a second force F2 are applied thereto. Therefore, a third force F3 that pulls the metal film 80 in the direction opposite to the first force F1 is generated, so that a hole that penetrates the metal film 80 up and down is formed at a position corresponding to the first through hole 72. It is possible to suppress the concentration of stress on the edge as compared with the configured configuration. As shown in FIG. 5, a pin insertion hole 14 that vertically penetrates the metal film 80 is formed at a position corresponding to the second through hole 74 of the graphite sheet 70. However, the inner cover portion 88 of the metal film 80 has a sufficient thickness, and the connecting portion 90 prevents the upper cover portion 82 and the lower cover portion 84 from peeling from the graphite sheet 70, so that the pin insertion hole is formed. The peeling of the metal film 80 from the graphite sheet 70 is suppressed in the vicinity of 14.

Further, according to the electrostatic chuck 100 of the present embodiment, peeling of the metal film 80 from the graphite sheet 70 is suppressed even in the manufacturing stage of the electrostatic chuck 100. That is, when the metal film 80 is formed on the graphite sheet 70 by thermal spraying as described above (S120 in FIG. 6), the metal film 80 and the graphite sheet 70 each thermally expand due to the heat generated by thermal spraying. After that, a cooling treatment is performed to lower the temperature of the graphite sheet 70 coated with the metal film 80 to room temperature. Here, the coefficient of thermal expansion of the material (metal) for forming the metal film 80 is larger than the coefficient of thermal expansion of the material (carbon) for forming the graphite sheet 70. Therefore, the amount of shrinkage of the metal film 80 per unit time is larger than the amount of shrinkage of the graphite sheet 70 per unit time, particularly at the beginning of the cooling treatment. That is, the metal film 80 contracts rapidly with respect to the graphite sheet 70. Therefore, tensile stress acts on the metal film 80. However, according to the present embodiment, since the upper cover portion 82 and the lower cover portion 84 are connected via the connecting portion 90, a metal film is formed from the graphite sheet 70 in the manufacturing stage (cooling treatment) of the electrostatic chuck 100. It is possible to prevent the 80 from peeling off.

Further, as described above, a pin insertion hole 14 that vertically penetrates the metal film 80 is formed at a position corresponding to the second through hole 74. As described above, the holding plate 10 may have a cavity that must be functionally formed. When a cavity exists in such a holding plate 10, the place where the cavity exists becomes a singular point of the temperature distribution due to the difference in heat transfer coefficient between the place where the cavity exists and the place where the cavity does not exist. There is a risk of becoming. However, usually, the arrangement pattern of the heater 52 and the temperature control are often adjusted so as to prevent the location where the cavity exists from becoming a singular point of the temperature distribution. On the other hand, in the graphite sheet 70, the first through hole 72 is filled with metal due to the difference in heat transfer coefficient between the place where the first through hole 72 is present (metal) and the place where the first through hole 72 is not present (carbon). There is a possibility that the place where the through hole 72 is present becomes a singular point of the temperature distribution. Therefore, in the present embodiment, in the graphite sheet 70, the inner diameter D1 of the first through hole 72 is smaller than the inner diameter D2 of the second through hole 74 in which the cavity (pin insertion hole 14) is formed. As a result, the suction surface S1 is formed by forming a singular point of the temperature distribution in the first through hole 72 as compared with the case where the inner diameter D1 of the first through hole 72 is larger than the inner diameter D2 of the second through hole 74. It is possible to suppress the occurrence of temperature unevenness.

Further, according to the present embodiment, the plurality of first through holes 72 are arranged at substantially equal intervals with each other in the vertical view. As a result, it is possible to suppress the occurrence of temperature unevenness on the suction surface S1 due to the variation in the arrangement of the first through holes 72, as compared with the configuration in which the plurality of first through holes 72 are unevenly arranged. Can be done.

Further, according to the present embodiment, the metal film 80 and the connecting portion 90 are formed of the same material (metal). As a result, the connecting force between the upper cover portion 82 and the lower cover portion 84 can be improved as compared with the configuration in which the metal film 80 and the connecting portion 90 are made of different materials.

B. Modification example:
The technique disclosed in the present specification is not limited to the above-described embodiment, and can be transformed into various forms without departing from the gist thereof, and for example, the following modifications are also possible.

The configuration of the electrostatic chuck 100 in the above embodiment is merely an example and can be variously deformed. For example, in the above embodiment, the heater layer 50 (heater 52) is arranged between the ceramic layer 12 and the base plate 20, but the heater layer 50 (heater 52) is not limited to this, and the heater layer 50 (heater 52) is the ceramic layer 12. It may be arranged inside the base plate 20 or on the surface or inside of the base plate 20. Further, in the above embodiment, the insulating portion of the heater layer 50 (heater 52) is formed of ceramics, but the present invention is not limited to this, and the heater layer 50 (heater 52) may be formed of a heat-resistant resin material such as a polyimide resin.

In the above embodiment, the heat transfer layer 60 is arranged between the lower surface S4 of the ceramic layer 12 and the heater layer 50, but the present invention is not limited to this, and the heat transfer layer 60 is arranged inside the ceramic layer 12. It may be arranged between the heater layer 50 and the base plate 20. Further, in the above embodiment, the number of heat transfer layers 60 (graphite sheet 70) is one, but the number of heat transfer layers 60 (graphite sheet 70) is not limited to one. It may be a form divided into.

In the above embodiment, only one first through hole 72 may be formed in the graphite sheet 70. Further, only one second through hole 74 may be formed in the graphite sheet 70, or the second through hole 74 may not be formed. The second through hole 74 is not limited to the pin insertion hole 14, but may be limited to, for example, a gas hole formed in the holding plate 10 or an electrode terminal accommodating hole.

Further, in the above embodiment, the plurality of first through holes 72 are arranged at substantially equal intervals in the radial direction of the graphite sheet 70 and at substantially equal intervals in the circumferential direction of the graphite sheet 70. However, at least one of the radial direction and the circumferential direction may be unevenly arranged.

In the above embodiment, the metal film 80 is exemplified as the film, but the film is not limited to this, and a film formed of a material other than metal may be used. Further, in the above embodiment, the metal film 80 may not include at least one of the outer cover portion 86 and the inner cover portion 88.

In the above embodiment, the connecting portion 90 is in contact with the inner peripheral wall forming the first through hole 72 over the entire circumference (see FIG. 4 and the like), but the connecting portion 90 is not limited to this, and the connecting portion 90 is the first. It may not be in contact with at least a part of the inner peripheral wall constituting the through hole 72 of the above. Further, in the above embodiment, the connecting portion 90 is integrally formed of the same material as the metal film 80, but the present invention is not limited to this, and instead of the connecting portion 90, the connecting portion 90 is different from the metal film 80. It may be an independent connecting portion formed independently by the material. The heat transfer coefficient of the independent connecting portion is preferably lower than the heat transfer coefficient of the metal film 80. Examples of the material for forming the independent connecting portion include metallic titanium, polyimide resin, and silicone resin. As a result, as compared with the case where the heat transfer coefficient of the independent connecting portion is equal to or higher than the heat transfer coefficient of the metal film 80, a singular point of the temperature distribution is formed in the first through hole 72, resulting in temperature unevenness on the suction surface S1. Can be suppressed from occurring. Further, it is preferable that the heat transfer coefficient of the independent connecting portion is substantially the same as the heat transfer coefficient in the vertical direction (Z-axis direction) of the graphite sheet 70.

Further, in the above embodiment, the refrigerant flow path 21 is formed inside the base plate 20, but the refrigerant flow path 21 is not inside the base plate 20 but on the surface of the base plate 20 (for example, with the base plate 20). It may be formed between the bonding layer 30). Further, in the above embodiment, a bipolar method in which a pair of internal electrodes 40 are provided inside the holding plate 10 is adopted, but a unipolar method in which one internal electrode 40 is provided inside the holding plate 10 is adopted. It may be adopted. Further, the material forming each member in the above embodiment is merely an example, and each member may be formed of another material.

Further, the method for manufacturing the electrostatic chuck 100 in the above embodiment is merely an example, and various modifications can be made.

Further, the present invention is not limited to the electrostatic chuck 100 that holds the semiconductor wafer W by utilizing electrostatic attraction, and other holding devices (for example, a vacuum chuck, a heater, etc.) that hold an object on the surface of a ceramic plate. ) And heating equipment.

10: Holding plate 12: Ceramic layer 14: Pin insertion hole 20: Base plate 21: Refrigerant flow path 22: Through hole 30: Bonding layer 40: Internal electrode 50: Heater layer 52: Heater 60: Heat transfer layer 70: Graphite sheet 70A: Graphite upper surface 70B: Graphite lower surface 72: First through hole 74: Second through hole 80: Metal film 82: Upper cover part 82A: Communication hole 84: Lower cover part 84A: First communication hole 86: Outside Cover part 88: Inner cover part 90: Second connecting part 100: Electrostatic chuck D1, D2: Inner diameter F1 to F3: Force S1: Adsorption surface S2: Ceramic side joint surface S3: Base side joint surface S4: Bottom surface W: Semiconductor wafer

Claims (4)

A ceramic layer having a first surface substantially orthogonal to the first direction and a second surface opposite to the first surface, and formed of ceramics.
A heater layer arranged inside the ceramic layer or on the second surface side of the ceramic layer and having a resistance heating element.
Heat disposed at at least one of the positions between the first surface of the ceramic layer and the heater layer and the position opposite to the first surface of the ceramic layer with respect to the heater layer. A heat transfer layer including an anisotropic heat transfer body arranged so that the heat transfer coefficient in the plane direction orthogonal to the first direction is higher than the heat transfer coefficient in the first direction. In a holding device for holding an object on the first surface of the ceramic layer.
The anisotropic heat transfer body is formed with a first through hole that penetrates from the third surface on one side of the anisotropic heat transfer body to the fourth surface on the other side in the first direction. And
The heat transfer layer further includes a coating and a connecting portion.
The coating is
A first surface that covers the third surface of the anisotropic heat transfer body and is coated on the third surface so as to close the opening of the first through hole formed on the third surface. Cover part and
A second surface that covers the fourth surface of the anisotropic heat transfer body and is coated on the fourth surface so as to close the opening of the first through hole formed on the fourth surface. Including the cover part of
The connecting portion is located in the first through hole and connects the first cover portion and the second cover portion .
The anisotropic heat transfer body is further formed with a second through hole that penetrates from the third surface to the fourth surface and has an inner diameter larger than that of the first through hole.
A holding device , wherein each of the first cover portion and the second cover portion is formed with a communication hole that communicates with the second through hole. In the holding device according to claim 1,
A plurality of the first through holes are formed in the anisotropic heat transfer body.
The holding device, wherein the plurality of first through holes are arranged at substantially equal intervals with respect to each other in the first directional view. In the holding device according to claim 1 or 2.
The holding device, characterized in that the connecting portion contains a material having a heat transfer coefficient lower than that of the coating film. A ceramic layer having a first surface substantially orthogonal to the first direction and a second surface opposite to the first surface, and formed of ceramics.
A heater layer arranged inside the ceramic layer or on the second surface side of the ceramic layer and having a resistance heating element.
Heat disposed at at least one of the positions between the first surface of the ceramic layer and the heater layer and the position opposite to the first surface of the ceramic layer with respect to the heater layer. A heat transfer layer including an anisotropic heat transfer body arranged so that the heat transfer coefficient in the plane direction orthogonal to the first direction is higher than the heat transfer coefficient in the first direction. In a holding device for holding an object on the first surface of the ceramic layer.
The anisotropic heat transfer body is formed with a first through hole that penetrates from the third surface on one side of the anisotropic heat transfer body to the fourth surface on the other side in the first direction. And
The heat transfer layer further includes a coating and a connecting portion.
The coating is
A first surface that covers the third surface of the anisotropic heat transfer body and is coated on the third surface so as to close the opening of the first through hole formed on the third surface. Cover part and
A second surface that covers the fourth surface of the anisotropic heat transfer body and is coated on the fourth surface so as to close the opening of the first through hole formed on the fourth surface. Including the cover part of
The connecting portion is located in the first through hole and connects the first cover portion and the second cover portion.
A holding device, characterized in that the connecting portion and the coating film are made of the same material.

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