Substrate holding member

Abstract

[Technical Problem to be Solved]: To provide a substrate holding member with a shaft that can suppress unevenness in the contact between the substrate and the mounting surface. [Technical Means for Solving the Problem]: The substrate holding member 100 includes a ceramic substrate 110. An annular protrusion 152 and a plurality of protrusions 156 are provided on the upper surface 111 of the ceramic substrate 110. A shaft 130 having a cylindrical portion 131 is joined to the lower surface 113 of the ceramic substrate 110. Furthermore, a circular region Sc concentric with the ceramic substrate 110 is provided at the center of the upper surface 111. The diameter Φc of the circular region Sc is at least 0.4 times the inner diameter Φ1 of the cylindrical portion 131 of the shaft 130. The envelope surface P1 of the upper surface 156a of the protrusion 156 in the circular region Sc is a plane, and the envelope surface P2 of the upper surface 156a of the protrusion 156 in the outer region Sout located outside the circular region Sc is an upwardly convex curved surface.

Description

Technical Field

[0001] This invention relates to a substrate holding member for holding substrates such as silicon wafers. Prior Technology

[0002] Patent Document 1 discloses a substrate holding member with a shaft for holding substrates such as wafers. The substrate holding member described in Patent Document 1 includes: a plate-shaped ceramic substrate with an embedded resistive heating element (heater electrode); and a tubular member (shaft) joined to the center of the lower surface of the ceramic substrate, containing a power supply rod connected to the resistive heating element. The upper surface (heating surface) of the ceramic substrate serves as the mounting surface for placing the substrate. The mounting surface of the ceramic substrate has a monotonous convex shape, highest in the center and gradually decreasing towards the periphery. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2005-109169 Summary of the Invention

[0004] [The problem the invention aims to solve] In the substrate holding member described in Patent Document 1, the mounting surface has a monotonous convex shape. By adsorbing the substrate onto the mounting surface, the substrate may sometimes be adsorbed at an angle while being held on the mounting surface. As a result, especially at the outer periphery of the substrate, there is a concern that local gaps may be generated between the substrate and the mounting surface, and there is a concern that the adhesion between the substrate and the mounting surface may become uneven.

[0005] The present invention was developed in view of this situation, and its purpose is to provide a substrate holding member that can suppress the unevenness of the adhesion between the substrate and the mounting surface. [Methods used to solve problems]

[0006] According to the present invention, a substrate holding member is provided, characterized in that it comprises: A ceramic substrate having a top surface and a bottom surface facing the top surface in the vertical direction; Electrodes are embedded in or disposed beneath the aforementioned ceramic substrate; and The shaft has a cylindrical portion that engages with the aforementioned lower surface of the ceramic substrate; The aforementioned ceramic substrate has the following characteristics: An annular protrusion is disposed on the outer periphery of the aforementioned upper surface of the ceramic substrate, and protrudes upwards further than the aforementioned upper surface of the ceramic substrate; and A plurality of protrusions are disposed on the aforementioned upper surface of the ceramic substrate, inside the aforementioned annular protrusions, and protrude upwards further than the aforementioned upper surface of the ceramic substrate. A circular region is provided in the center of the aforementioned ceramic substrate. This circular region is concentric with the aforementioned ceramic substrate, and its diameter is at least 0.4 times the inner diameter of the aforementioned cylindrical portion. The envelope surface above the aforementioned plurality of protrusions arranged in the aforementioned circular region, i.e., the first envelope surface, is a plane, and the envelope surface above the aforementioned plurality of protrusions arranged on the outer side of the aforementioned circular region, i.e., the second envelope surface, is a curved surface. or, The aforementioned first envelope surface is a surface with a first curvature, and the aforementioned second envelope surface is a plane or a surface with a second curvature that is different from the aforementioned first curvature. [Effects of the Invention]

[0007] In the above-described configuration, since an annular protrusion is provided on the outer periphery of the ceramic substrate, deformation of the outer edge of the substrate can be suppressed when the substrate is adsorbed onto the ceramic substrate. Furthermore, the first envelope surface is planar and the second envelope surface is curved. Alternatively, the first envelope surface is a curved surface with a first curvature, and the second envelope surface is either planar or a curved surface with a second curvature different from the aforementioned first curvature. Therefore, when the substrate is adsorbed onto the ceramic substrate, the entire surface of the substrate can be quickly stabilized. Furthermore, it is possible to prevent the substrate from being adsorbed onto the ceramic substrate in an inclined state. Therefore, it is possible to suppress the localized generation of gaps between the substrate and the annular protrusion. This, in turn, suppresses the generation of hot spots on the substrate and suppresses uneven temperature distribution on the substrate. Simple Explanation of the Diagram

[0008] Figure 1 is a schematic diagram of the substrate holding member 100. Figure 2 is a schematic diagram of the electrode 124 for electrostatic adsorption. Figure 3 is a schematic diagram of electrode 120. Figure 4 is a schematic view of the substrate holding member 100 with shaft 130. Figures 5(a) to (e) are flowcharts illustrating the manufacturing method of the ceramic substrate 110. Figures 6(a) to (d) are flowcharts illustrating other manufacturing methods of the ceramic substrate 110. Figure 7 is a schematic diagram of the substrate holding member 200. Figure 8 is a schematic diagram of the substrate holding member 300. Figure 9 is a schematic diagram of the substrate holding member 400. Figure 10 is a schematic diagram of the substrate holding member 500. Figure 11 is a schematic diagram of the substrate holding member 600. Implementation

[0009] [The form in which the invention is carried out] <First Implementation Form> <Substrate holding member 100> The substrate holding member 100 of the first embodiment of the present invention will be described with reference to FIG1. ​​The substrate holding member 100 of this embodiment is a ceramic heater used for heating semiconductor wafers (hereinafter referred to as wafer 10) such as silicon wafers. In the following description, the vertical direction 5 is defined based on the state in which the substrate holding member 100 is set in a usable manner (the state in FIG1). As shown in FIG1, the substrate holding member 100 of this embodiment includes: a ceramic substrate 110, an electrode 120 (see FIG2, 3), an electrostatic adsorption electrode 124 (see FIG2), a shaft 130, and a power supply line 140 (see FIG4).

[0010] The ceramic substrate 110 is a circular plate-shaped component with a diameter of 12 inches (approximately 300 mm), on which the wafer 10, which is the object to be heated, is mounted. As shown in FIG1, the lower surface 113 of the ceramic substrate 110 may be a flat surface. Alternatively, as shown in FIG4, a protrusion 114 (hereinafter referred to as the engagement protrusion 114) for engaging with the shaft 130 may be provided on the lower surface 113 of the ceramic substrate 110. Furthermore, as shown in FIG1, the upper surface 111 of the ceramic substrate 110 has a convex curved surface shape in which the center is bulging higher than the outer periphery (in FIG2 and 4, for the sake of simplification, the upper surface 111 of the ceramic substrate 110 is shown as a flat surface). For example, in this embodiment, the central portion of the upper surface 111 of the ceramic substrate 110 is 20 μm higher than the outer periphery (outer edge). On the top surface 111 of the ceramic substrate 110, an annular protrusion 152 (hereinafter referred to as the annular protrusion 152) and a plurality of protrusions 156 are provided. Inside the ceramic substrate 110, a first gas flow path 164, described later, is formed. The ceramic substrate 110 can be formed by a sintered ceramic body such as aluminum nitride, silicon carbide, alumina, or silicon nitride.

[0011] As shown in Figure 1, the annular protrusion 152 is a generally annular protrusion disposed on the outer periphery of the upper surface 111 of the ceramic substrate 110, protruding upwards further than the upper surface 111. When the wafer 10 is placed on the ceramic substrate 110, the upper surface 152a of the annular protrusion 152 abuts against the lower surface of the wafer 10. That is, when the wafer 10 is placed on the ceramic substrate 110, the annular protrusion 152 is disposed at a position overlapping with the wafer 10 in the vertical direction 5.

[0012] Inside the annular protrusion 152 on the upper surface 111 of the ceramic substrate 110, a plurality of protrusions 156 arranged in a concentric circle are provided. Each of the protrusions 156 has a cylindrical shape. In this embodiment, the upper surface of the protrusion 156 is processed in the circular region Sc located at the center of the ceramic substrate 110 such that the envelope surface P1 of the upper surface 156a of the protrusion 156 is a horizontal plane (in this embodiment, a plane parallel to the lower surface 113 of the ceramic substrate 110). Furthermore, the term "enveloping surface" refers to a surface whose height difference with the plurality of protrusions 156 is less than 2 μm. In this embodiment, the envelope surface P2, defined in this way, is a horizontal plane. The envelope surface P1 is an example of the first envelope surface disclosed herein. In this embodiment, the outer region Sout, located outside the circular region Sc, is machined such that the envelope surface P2 of the upper surface 156a of the protrusion 156 is a convex surface (convex curved surface) that bulges towards the center. The envelope surface P2 is an example of the second envelope surface disclosed herein. In this embodiment, the height H1 of the envelope surface P2 is 20 μm. Furthermore, as shown in FIG7, the height H1 of the envelope surface P2 is defined as the difference between the height of the highest and lowest positions of the envelope surface P2. The highest position of the envelope surface P2 can be approximated by using a circular arc or a quadratic curve to approximate the cross-section of the envelope surface passing through the center. In this embodiment, the height difference Δ between the envelope surface P1 and the envelope surface P2 is 5 μm. Furthermore, the height difference Δ between the envelope surface P1 and the envelope surface P2 is designed to be in the range of 3 μm to 10 μm.

[0013] As shown in Figure 1, the diameter ϕc of the circular region Sc is larger than the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130, and smaller than the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130 (ϕ1 < ϕc < ϕ2). In this embodiment, the diameter ϕc of the circular region Sc is 20 mm, the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130 is 45 mm, and the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130 is 65 mm. However, the diameter ϕc of the circular region Sc, the inner diameter ϕ1 of the cylindrical portion 131, and the maximum outer diameter ϕ2 are not limited to these values. The diameter ϕc of the circular region Sc can be set to 0.4 times or more of the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130. Furthermore, the diameter ϕc of the circular region Sc can be set to 1.5 times or less of the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130.

[0014] The height of the annular protrusion 152 (the length 5 in the vertical direction from the top 111) can be set in the range of 5μm to 2mm. Similarly, the height of the plurality of protrusions 156 can also be set in the range of 5μm to 2mm.

[0015] The annular protrusion 152 preferably has a fixed width, which can be set from 0.1 mm to 10 mm. The surface roughness Ra of the upper surface 152a of the annular protrusion 152 can be set to 1.6 μm or less. The surface roughness Ra of the upper surface 156a of the plurality of protrusions 156 can be set to 1.6 μm or less. Furthermore, the surface roughness Ra of the upper surface 152a of the annular protrusion 152 and the upper surface 156a of the plurality of protrusions 156 is preferably 0.4 μm or less, more preferably 0.2 μm or less, and even more preferably 0.1 μm or less. For example, in this embodiment, the width of the annular protrusion 152 is 3 mm, and the surface roughness Ra of the upper surface 152a of the annular protrusion 152 and the upper surface 156a of the plurality of protrusions 156 is 0.4 μm.

[0016] The upper surface 156a of the plurality of protrusions 156 is preferably a circle with a diameter of 0.1 mm to 5 mm. Furthermore, the spacing between each of the plurality of protrusions 156 can be set in the range of 1.5 mm to 30 mm. For example, in this embodiment, the upper surface 156a of the plurality of protrusions 156 is a circle with a diameter of 2 mm, and the spacing between the plurality of protrusions 156 arranged on each concentric circle is set to 10 mm to 15 mm.

[0017] As shown in Figure 1, a first gas flow path 164 is formed inside the ceramic substrate 110. The eight openings 164a of the first gas flow path 164 open into the circular region Sc on the upper 111. In the circular region Sc, the eight openings 164a are arranged in a circle at equal intervals (45° intervals). The first gas flow path 164 extends downwards from each of the eight openings 164a, then extends horizontally and merges, continuing to extend downwards. The lower end of the first gas flow path 164 is joined to the upper end of a second gas flow path 168 formed inside the shaft 130.

[0018] The first gas flow path 164 can be used as a flow path to supply gas to the space (gap) defined by the upper surface 111 of the ceramic substrate 110 and the lower surface of the wafer 10. For example, a heat transfer gas for heat transfer between the wafer 10 and the ceramic substrate 110 can be supplied. As the heat transfer gas, inactive gases such as helium or argon, or nitrogen, can be used. The heat transfer gas system is supplied through the first gas flow path 164 at a pressure set in the range of 100 Pa to 40000 Pa. Furthermore, when process gas enters the gap inside the annular protrusion 152 from the gap between the upper surface 152a of the annular protrusion 152 and the lower surface of the wafer 10, the gas can be discharged through the first gas flow path 164. At this time, by adjusting the exhaust pressure, the pressure difference between the pressure outside the gap and the pressure inside the gap can be adjusted. This allows the wafer 10 to be adsorbed onto the upper surface of the ceramic substrate 110.

[0019] As shown in Figure 2, an electrostatic adsorption electrode 124 and an electrode 120 (an example of the heating element of the present invention) are embedded inside the ceramic substrate 110. As shown in Figure 2, the electrostatic adsorption electrode 124 is arranged in a manner where two semi-circular electrodes 124a and 124b face each other at a predetermined interval (5 mm), and have a generally circular shape. The outer diameter of the electrostatic adsorption electrode 124 is 294 mm. As shown in Figure 3, the electrode 120 is a strip-shaped metal mesh or foil. The outer diameter of the electrode 120 is 298 mm. The electrode 120 does not protrude from the side of the ceramic substrate 110. A terminal portion 121 for connection to the power supply line 140 (see Figure 4) is provided approximately in the center of the electrode 120. The electrode 120 is formed of a heat-resistant metal (high-melting-point metal) such as a mesh or foil woven with tungsten (W), molybdenum (Mo), or an alloy containing molybdenum and / or tungsten. The purity of tungsten and molybdenum is preferably 99% or higher. The thickness of electrode 120 is 0.15 mm or less. Furthermore, from the viewpoint of increasing the resistance of electrode 120 and reducing the current consumption of substrate holding member 100, it is preferable to set the wire diameter of the lead to 0.1 mm or less and the thickness of electrode 120 to 0.1 mm or less. Also, the width of electrode 120 cut into a strip shape is preferably 2.5 mm to 20 mm, more preferably 5 mm to 15 mm. In this embodiment, electrode 120 is cut into the shape shown in FIG. 3, but the shape of electrode 120 is not limited to this and can be appropriately changed. Furthermore, it is not limited to both electrostatic adsorption electrode 124 and electrode 120 being embedded inside the ceramic substrate 110. For example, it is also possible that only either electrostatic adsorption electrode 124 or electrode 120 is embedded inside the ceramic substrate 110. Alternatively, in addition to at least one of electrode 120 and electrostatic adsorption electrode 124, a plasma electrode for generating plasma can also be embedded above the ceramic substrate 110. Alternatively, a plasma electrode can be embedded instead of electrode 120 and electrostatic adsorption electrode 124.

[0020] As shown in Figures 1 and 4, a shaft 130 is connected to the lower surface 113 of the ceramic substrate 110. As mentioned above, the lower surface 113 of the ceramic substrate 110 may be a flat surface (see Figure 1), or a engagement protrusion 114 for engaging with the shaft 130 may be provided on the lower surface 113 of the ceramic substrate 110 (see Figure 4). As shown in Figure 1, the shaft 130 has a hollow, generally cylindrical portion 131. At the upper end of the cylindrical portion 131, a flange portion 133 with the largest outer diameter (ϕ2) is provided (see Figure 1). Furthermore, as shown in Figure 4, the shaft 130 may also have a large-diameter portion 132 provided below the cylindrical portion 131. The large-diameter portion 132 has a diameter larger than the diameter of the cylindrical portion 131. In the following description, the length direction of the cylindrical portion 131 is defined as the length direction 6 of the shaft 130. As shown in Figures 1 and 4, in the use state of the substrate holding member 100, the length direction 6 of the shaft 130 is parallel to the vertical direction 5.

[0021] Furthermore, when a joining protrusion 114 is formed on the lower surface 113 of the ceramic substrate 110, the shape of the joining protrusion 114 is preferably the same as the shape of the upper surface of the cylindrical portion 131 of the shaft 130 to be joined, and the diameter of the joining protrusion 114 is preferably 100 mm or less. The height of the joining protrusion 114 (the height from the lower surface 113) is only required to be 0.2 mm or more, preferably 2 mm or more. There is no particular upper limit to the height, but considering ease of manufacturing, the height of the joining protrusion 114 is preferably 20 mm or less. Also, the lower surface of the joining protrusion 114 is preferably parallel to the lower surface 113 of the ceramic substrate 110. The surface roughness Ra of the lower surface of the joining protrusion 114 is only required to be 1.6 μm or less. Furthermore, the surface roughness Ra of the lower surface of the joining protrusion 114 is preferably 0.4 μm or less, more preferably 0.2 μm or less.

[0022] The upper part of the cylindrical portion 131 is fixed to the lower part 113 of the ceramic substrate 110 (or the lower part of the joining protrusion 114 if a joining protrusion 114 is provided). Furthermore, the shaft 130 is formed of a sintered ceramic body made of aluminum nitride, silicon carbide, alumina, silicon nitride, etc., just like the ceramic substrate 110. Alternatively, to improve thermal insulation, it may be formed of a material with a lower thermal conductivity than the ceramic substrate 110.

[0023] As shown in Figures 1 and 4, the shaft 130 has a hollow cylindrical shape, and a through hole extending in the longitudinal direction 6 is formed inside it (in the region further inward than the inner diameter). A power supply line 140 (see Figure 4) for supplying power to the electrode 120 is disposed in the hollow portion (through hole) of the shaft 130. The upper end of the power supply line 140 is electrically connected to a terminal portion 121 (see Figure 3) disposed in the center of the electrode 120. The power supply line 140 is connected to a power source for a heater (not shown). Thus, power is supplied to the electrode 120 through the power supply line 140.

[0024] Furthermore, as shown in Figure 1, a gas flow path 168 extending in the vertical direction 5 is formed in the cylindrical portion 131 of the shaft 130. As mentioned above, the upper end of the gas flow path 168 is connected to the lower end of the first gas flow path 164. In addition, the gas flow path 168 may not necessarily be formed in the cylindrical portion 131 of the shaft 130, and a gas pipe may be provided in a region further inside the inner diameter of the cylindrical portion 131.

[0025] Next, the manufacturing method of the substrate holding member 100 will be described. Hereinafter, the ceramic substrate 110 and the shaft 130 will be described as examples of aluminum nitride forming.

[0026] First, the manufacturing method of the ceramic substrate 110 will be described. As shown in FIG5(a), granulated powder P, mainly composed of aluminum nitride (AlN) powder, is fed into a carbon-based bottomed mold 601 and temporarily pressurized by a punch 602. Furthermore, it is preferable that the granulated powder P contains 5 wt% or less of a sintering aid (e.g., Y2O3). Next, as shown in FIG5(b), an electrode 120, cut to a predetermined shape, is placed on the temporarily pressurized granulated powder P. Furthermore, the electrode 120 is arranged parallel to the surface perpendicular to the pressing direction (the bottom surface of the bottomed mold 601). At this time, W pellets or Mo pellets may also be embedded at the terminals 121 (see FIG3) of the electrode 120.

[0027] As shown in Figure 5(c), granulated powder P is further fed into a bottom mold 601 to cover electrode 120, and then pressed by a punch 602 to form the granulated powder. Next, as shown in Figure 5(d), the granulated powder P with electrode 120 embedded is fired under pressure. The pressure applied during firing is preferably 1 MPa or higher. Also, it is preferably fired at a temperature of 1800°C or higher. Then, as shown in Figure 5(e), blind holes are formed up to electrode 120 in order to form terminal 121. In addition, if pellets are embedded, blind holes are only formed up to the pellets. Furthermore, through holes are formed that become part of the first gas flow path 164. In this way, a ceramic substrate 110 with the first gas flow path 164 formed inside can be manufactured. In this case, a predetermined escape is provided in a way that the electrode 120 is not exposed from the first gas flow path 164.

[0028] Furthermore, the ceramic substrate 110 can be manufactured by the following method. As shown in FIG6(a), a binder is added to the granulated aluminum nitride powder P for CIP molding, and processed into a disc shape to produce an aluminum nitride molded body 610. Next, as shown in FIG6(b), the molded body 610 is degreased to remove the binder.

[0029] As shown in Figure 6(c), a recess 511 for embedding the electrode 120 is formed in the degreased molded body 610. The electrode 120 is placed in the recess 511 of the molded body 610, and another molded body 610 is laminated. Alternatively, the recess 511 can be pre-formed in the molded body 610. Next, as shown in Figure 6(d), the molded body 610 laminated in a manner that holds the electrode 120 is fired under pressure to produce a fired body. The pressure applied during firing is preferably 1 MPa or more. Also, it is preferable to fire at a temperature of 1800°C or more. The steps after the firing body is produced are the same as the steps described above, so they are omitted from the description.

[0030] The upper surface 111 of the ceramic substrate 110 formed in this manner is ground and lapped (mirror polishing). Further, by sandblasting the upper surface 111, a plurality of protrusions 156 and annular protrusions 152 are formed on the upper surface 111. A joining protrusion 114 protruding from the lower surface 113 of the ceramic substrate 110 may also be provided (see Figure 4).

[0031] Next, the manufacturing method of the shaft 130 and the bonding method between the shaft 130 and the ceramic substrate 110 will be described. First, granulated aluminum nitride powder P, which contains a few wt% binder, is formed under hydrostatic pressure (approximately 1 MPa) to form a molded body into a predetermined shape. Furthermore, the outer diameter of the shaft 130 is approximately 30 mm to 100 mm. As mentioned above, a flange portion 133 with the largest outer diameter may also be provided on the end face of the cylindrical portion 131 of the shaft 130 (see Figure 1). The length of the cylindrical portion 131 may be, for example, 50 mm to 500 mm. At this time, a through hole serving as a second gas flow path 168 is formed in the molded body. Then, the molded body is fired in a nitrogen atmosphere. For example, it is fired at a temperature of 1900°C for 2 hours. After firing, the sintered body is then processed into a predetermined shape to form the shaft 130. The upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic substrate 110 can be fixed by diffusion bonding under an axial pressure of 1 MPa or higher at a temperature of 1600°C or higher. In this case, the surface roughness Ra of the lower surface 113 of the ceramic substrate 110 is preferably 0.4 μm or less, and more preferably 0.2 μm or less. Alternatively, the upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic substrate 110 can be bonded using an adhesive. For example, an AlN bonding paste containing 10 wt% Y2O3 can be used as the adhesive. For example, the AlN bonding paste is applied to the interface between the upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic substrate 110 with a thickness of 15 μm, and a force of 5 kPa is applied in a direction perpendicular to the upper surface 111 (the longitudinal direction 6 of the shaft 130), while heating at a temperature of 1700°C for 1 hour, thereby achieving bonding. Alternatively, the upper part of the cylindrical part 131 and the lower part 113 of the ceramic substrate 110 can be fixed by screws, hard welding, or the like.

[0032] <Effects of the first implementation mode> In the first embodiment described above, the substrate holding member 100 includes a ceramic substrate 110. On the upper surface 111 of the ceramic substrate 110, there are: an annular protrusion 152 disposed on the outer periphery of the upper surface 111 and protruding upwards beyond the upper surface 111; and a plurality of protrusions 156 disposed on the inner side of the annular protrusion 152 and protruding upwards beyond the upper surface 111. On the lower surface 113 of the ceramic substrate 110, a shaft 130 having a cylindrical portion 131 is joined. Furthermore, at the center of the upper surface 111, a circular region Sc concentric with the ceramic substrate 110 is provided. The diameter ϕc of the circular region Sc is 70 mm, which is at least 0.4 times the inner diameter ϕ1 (45 mm) of the cylindrical portion 131 of the shaft 130. In the first embodiment, the envelope surface P1 of the upper surface 156a of the plurality of protrusions 156 disposed on the circular region Sc is a horizontal plane. In contrast, the envelope surface P2 of the upper 156a of the plurality of protrusions 156 disposed in the outer region Sout is a convex surface (a curved surface protruding upwards) that bulges toward the center of the ceramic substrate 110. In other words, the curvature of the envelope surface P1 is zero, while the curvature of the envelope surface P2 is a non-zero value. That is to say, the curvatures of the envelope surfaces P1 and P2 are different from each other.

[0033] Because annular protrusions 152 are provided on the outer periphery of the ceramic substrate 110, deformation of the outer edge of the wafer 10 can be suppressed when it is adsorbed onto the top surface of the ceramic substrate 110. Furthermore, in the circular region Sc of the top surface 111 of the ceramic substrate 110, the envelope surface P1 of the top surface 156a of the plurality of protrusions 156 becomes a flat (horizontal) plane. Therefore, when the wafer 10 is adsorbed onto the ceramic substrate 110 by vacuum adsorption, electrostatic adsorption, etc., the stability of the wafer 10 in the central portion of the wafer 10 is improved. Thus, firstly, the central portion of the wafer 10 is adsorbed, and the central portion of the wafer 10 is planarized. Then, in the outer region Sout, adsorption proceeds sequentially outwards, and the wafer 10 is adsorbed along the envelope surface P2. Therefore, when the wafer 10 is adsorbed onto the ceramic substrate 110, the entire surface of the wafer 10 can be quickly stabilized. Furthermore, firstly, the central portion of wafer 10 is adsorbed, and the central portion of wafer 10 is planarized. Then, adsorption occurs sequentially in the outer region (Sout), facing outwards. Therefore, there is no concern that wafer 10 might be adsorbed onto the ceramic substrate 110 while tilted. Thus, the formation of gaps between wafer 10 and the annular protrusion 152 can be suppressed. This, in turn, suppresses the formation of hot spots on wafer 10 and reduces uneven temperature distribution on wafer 10.

[0034] <Second Implementation Form> Next, the substrate holding member 200 of the second embodiment of the present invention will be described with reference to FIG7. Furthermore, components identical to those in the substrate holding member 100 of the first embodiment are marked with the same reference numerals and their descriptions are omitted.

[0035] As shown in FIG7, the substrate holding member 200 includes a ceramic substrate 110, which is the same as that of the substrate holding member 100 in the first embodiment. The first gas flow path 164 described above is formed inside the ceramic substrate 110, and electrodes 120 (see FIG2 and FIG3) and electrostatic adsorption electrodes 124 (see FIG2) are embedded therein. Furthermore, a shaft 130 is joined to the underside 113 of the ceramic substrate 110.

[0036] An annular protrusion 152 and a plurality of protrusions 156 disposed on the inner side of the annular protrusion 152 are provided on the upper surface 111 of the ceramic substrate 110. In the circular region Sc located in the center of the upper surface 111 of the ceramic substrate 110, the upper surface of the protrusion 156 is processed such that the envelope surface P1 of the upper surface 156a of the protrusion 156 is a concave surface (a downwardly convex curved surface). In the outer region Sout located outside the circular region Sc, similarly to the first embodiment, the upper surface of the protrusion 156 is processed such that the envelope surface P2 of the upper surface 156a of the protrusion 156 is along the curved surface of the upper surface 111 of the ceramic substrate 110. In the second embodiment, the depth D1 of the concavity of the envelope surface P1 is 3 μm to 10 μm, and the height H2 of the envelope surface P2 is 20 μm.

[0037] In the second embodiment, the diameter ϕc of the circular region Sc is 30 mm, which is at least 0.4 times the inner diameter ϕ1 (45 mm) of the cylindrical portion 131 of the shaft 130. As described above, in the second embodiment, the envelope surface P1 of the upper surface 156a of the plurality of protrusions 156 disposed in the circular region Sc is a concave surface (a downwardly convex curved surface) that is recessed toward the center of the ceramic substrate 110. In contrast, the envelope surface P2 of the upper surface 156a of the plurality of protrusions 156 disposed in the outer region Sout is a convex surface (an upwardly convex curved surface) that bulges toward the center of the ceramic substrate 110. That is, the curvatures of the envelope surfaces P1 and P2 are different from each other. As shown in Figure 7, the diameter ϕc of the circular region Sc is larger than the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130, and smaller than the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130 (ϕ1 < ϕc < ϕ2). Furthermore, similar to the first embodiment, the diameter ϕc of the circular region Sc can be set to be at least 0.4 times the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130. Also, the diameter ϕc of the circular region Sc can be set to be at least 1.5 times the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130.

[0038] In this embodiment, since annular protrusions 152 are provided on the outer periphery of the ceramic substrate 110, deformation of the outer edge of the wafer 10 can be suppressed when the wafer 10 is adsorbed toward the top surface of the ceramic substrate 110. Furthermore, in the circular region Sc of the top surface 111 of the ceramic substrate 110, the envelope surface P1 of the top surface 156a of the plurality of protrusions 156 becomes concave. Therefore, when the wafer 10 is adsorbed onto the ceramic substrate 110, the stability of the wafer 10 is improved in the central portion. Thus, the central portion of the wafer 10 is first adsorbed and stabilized. Then, adsorption proceeds sequentially in the outer region Sout, toward the outside, with the wafer 10 adsorbed along the envelope surface P2. In this case, when the wafer 10 is adsorbed onto the ceramic substrate 110, compared to the case where the envelope surface P1 of the circular region Sc is planar, the entire surface of the wafer 10 can be stabilized more quickly. Furthermore, similar to the first embodiment, the central portion of the wafer 10 is adsorbed first and stabilized thereafter, and then adsorption occurs sequentially in the outer region Sout, facing outwards. Therefore, there is no concern that the wafer 10 may be adsorbed onto the ceramic substrate 110 in an inclined state. Thus, the localized generation of gaps between the wafer 10 and the annular protrusion 152 can be suppressed. This, in turn, suppresses the generation of hot spots on the wafer 10 and suppresses uneven temperature distribution on the wafer 10.

[0039] <Third Implementation Form> Next, the substrate holding member 300 of the third embodiment of the present invention will be described with reference to FIG8.

[0040] As shown in FIG8, the substrate holding member 300 includes a ceramic substrate 110, which is the same as that of the substrate holding members 100 and 200 in the first and second embodiments. Similar to the first and second embodiments, the first gas flow path 164 described above is formed inside the ceramic substrate 110, and an electrode 120 (see FIG2 and FIG3) and an electrostatic adsorption electrode 124 (see FIG2) are embedded therein. Furthermore, a shaft 130 is joined to the underside 113 of the ceramic substrate 110.

[0041] As shown in Figure 8, an annular protrusion 152 and a plurality of protrusions 156 disposed on the inner side of the annular protrusion 152 are provided on the upper surface 111 of the ceramic substrate 110. In the circular region Sc located at the center of the upper surface 111 of the ceramic substrate 110, the upper surface of the protrusion 156 is machined such that the envelope surface P1 of the upper surface 156a of the protrusion 156 is a convex surface (an upwardly convex curved surface). In the outer region Sout located outside the circular region Sc, the upper surface of the protrusion 156 is machined such that the envelope surface P2 of the upper surface 156a of the protrusion 156 is a horizontal plane. In the third embodiment, the height H3 of the convex surface P1 is 10 μm. Furthermore, the height H3 of the convex surface P1 is defined as the difference between the height of the highest part of the envelope surface P1 and the height of the envelope surface P2.

[0042] In the third embodiment, the diameter ϕc of the circular region Sc is 90 mm, which is at least 0.4 times the inner diameter ϕ1 (45 mm) of the cylindrical portion 131 of the shaft 130. As described above, in the third embodiment, the envelope surface P1 of the upper surface 156a of the plurality of protrusions 156 disposed in the circular region Sc is a convex surface (an upwardly convex curved surface) that bulges toward the center of the ceramic substrate 110. In contrast, the envelope surface P2 of the upper surface 156a of the plurality of protrusions 156 disposed in the outer region Sout is a horizontal plane (in this embodiment, it is a plane parallel to the lower surface 113 of the ceramic substrate 110). That is, the curvatures of the envelope surface P1 and the envelope surface P2 are different from each other. Furthermore, the term "enveloping surface" refers to a surface whose height difference with the plurality of protrusions 156 is less than 2 μm. In this embodiment, the envelope surface P2 defined in this way is a horizontal plane. As shown in Figure 8, the diameter ϕc of the circular region Sc is larger than the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130, and smaller than the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130 (ϕ1 < ϕc < ϕ2). Furthermore, similar to the first embodiment, the diameter ϕc of the circular region Sc can be set to be at least 0.4 times the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130. Also, the diameter ϕc of the circular region Sc can be set to be at least 1.5 times the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130.

[0043] In this embodiment, since annular protrusions 152 are provided on the outer periphery of the ceramic substrate 110, deformation of the outer edge of the wafer 10 can be suppressed when it is adsorbed onto the top surface of the ceramic substrate 110. Furthermore, in the circular region Sc of the top surface 111 of the ceramic substrate 110, the envelope surface P1 of the top surface 156a of the plurality of protrusions 156 becomes a convex surface. Moreover, in the outer region Sout of the top surface 111 of the ceramic substrate 110, the envelope surface P2 of the top surface 156a of the plurality of protrusions 156 becomes a flat (horizontal) plane. Therefore, compared to the case where the entire top surface 111 of the ceramic substrate 110 has a monotonous convex shape for the envelope surface of the top surface 156a of the plurality of protrusions 156, the wafer 10 can be adsorbed uniformly on its outer periphery. In particular, even when wafer 10 is warped such that its central region is higher than its outer periphery, it can be quickly adsorbed and stabilized. Therefore, even in the case of wafer 10 warping as described above, there is no concern that wafer 10 will be adsorbed onto the ceramic substrate 110 in a tilted state. Thus, the formation of localized gaps between wafer 10 and the annular protrusion 152 can be suppressed. This suppresses the formation of hot spots on wafer 10 and reduces uneven temperature distribution on wafer 10.

[0044] <Fourth Implementation Form> Next, the substrate holding member 400 of the fourth embodiment of the present invention will be described with reference to FIG9.

[0045] As shown in FIG9, the substrate holding member 400 includes a ceramic substrate 410. Furthermore, similar to the first to third embodiments, an electrode 120 (see FIG2 and FIG3) and an electrostatic adsorption electrode 124 (see FIG2) are embedded inside the ceramic substrate 410. Additionally, a shaft 130 is joined to the underside 413 of the ceramic substrate 410.

[0046] As shown in Figure 9, a second gas flow path 465 is formed inside the ceramic substrate 410, replacing the first gas flow path 164 described above. In the circular region Sc of the upper 411, the four openings 465a of the second gas flow path 465 are formed. However, in Figure 9, only two of the four openings 465a are shown. Also, although not shown, in the circular region Sc, the four openings 465a are arranged in a circular shape at equal intervals (90° intervals). The second gas flow path 465 extends downwards from each of the four openings 465a, then extends horizontally and merges, further extending downwards. The lower end of the second gas flow path 465 is joined to the upper end of the gas flow path 168 formed inside the shaft 130.

[0047] As shown in Figure 9, the upper surface 411 of the ceramic substrate 410 has a concave curved surface shape in which the center is more recessed than the outer periphery. In this embodiment, the central portion of the upper surface 411 of the ceramic substrate 410 is 20 μm lower than the outer periphery (outer edge).

[0048] As shown in Figure 9, an annular protrusion 152 and a plurality of protrusions 156 disposed on the inner side of the annular protrusion 152 are provided on the upper surface 411 of the ceramic substrate 410. In the circular region Sc located at the center of the upper surface 411 of the ceramic substrate 410, the upper surface of the protrusion 156 is machined such that the envelope surface P1 of the upper surface 156a of the protrusion 156 is a flat (horizontal) plane. In the outer region Sout located outside the circular region Sc, the upper surface of the protrusion 156 is machined such that the envelope surface P2 of the upper surface 156a of the protrusion 156 is along the concave surface of the upper surface 411 of the ceramic substrate 410. In the fourth embodiment, the height H4 of the convex surface of the envelope surface P2 is 20 μm. Furthermore, the height H4 of the convex surface of the envelope surface P2 is defined as the difference between the height of the highest and lowest parts of the envelope surface P2.

[0049] In the fourth embodiment, the diameter ϕc of the circular region Sc is 55 mm, which is at least 0.4 times the inner diameter ϕ1 (45 mm) of the cylindrical portion 131 of the shaft 130. As described above, in the fourth embodiment, the envelope surface P1 of the upper surface 156a of the plurality of protrusions 156 disposed in the circular region Sc is a horizontal plane. In contrast, the envelope surface P2 of the upper surface 156a of the plurality of protrusions 156 disposed in the outer region Sout is a downwardly convex concave surface. That is, the curvatures of the envelope surfaces P1 and P2 are different from each other. As shown in FIG9, the diameter ϕc of the circular region Sc is smaller than the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130 (ϕc < ϕ2). Furthermore, similar to the first embodiment, the diameter ϕc of the circular region Sc can be set to be at least 0.4 times the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130. Furthermore, the diameter ϕc of the circular region Sc can be set to be less than 1.5 times the maximum outer diameter ϕ2 of the cylindrical part 131 of the shaft 130.

[0050] In this embodiment, since annular protrusions 152 are provided on the outer periphery of the ceramic substrate 110, deformation of the outer edge of the wafer 10 can be suppressed when it is adsorbed onto the top surface of the ceramic substrate 110. Furthermore, in the circular region Sc of the top surface 111 of the ceramic substrate 110, the envelope surfaces P1 of the top surfaces 156a of the plurality of protrusions 156 are flat (horizontal) planes. Moreover, in the outer region Sout of the top surface 111 of the ceramic substrate 110, the envelope surfaces P2 of the top surfaces 156a of the plurality of protrusions 156 are concave surfaces. Therefore, compared to the case where the envelope surfaces of the top surfaces 156a of the plurality of protrusions 156 are monotonously concave, uniform adsorption of the wafer 10 can be achieved on the outer periphery of the entire top surface 111 of the ceramic substrate 110. In particular, even when wafer 10 is warped such that its central region is lower than its outer periphery, it can be quickly adsorbed and stabilized. Therefore, even in the case of wafer 10 warping as described above, there is no concern that wafer 10 will be adsorbed onto the ceramic substrate 110 in a tilted state. Thus, the formation of localized gaps between wafer 10 and the annular protrusion 152 can be suppressed. This suppresses the formation of hot spots on wafer 10 and reduces uneven temperature distribution on wafer 10.

[0051] <Fifth Implementation Form> Next, the substrate holding member 500 of the fifth embodiment of the present invention will be described with reference to FIG10.

[0052] As shown in Figure 10, the substrate holding member 500 includes the same ceramic substrate 410 as the substrate holding member 400 in the fourth embodiment. Furthermore, similar to the fourth embodiment, the second gas flow path 465 described above is formed inside the ceramic substrate 410, and electrodes 120 (see Figures 2 and 3) and electrostatic adsorption electrodes 124 (see Figure 2) are embedded therein. Additionally, a shaft 130 is joined to the lower surface 413 of the ceramic substrate 410.

[0053] As shown in Figure 10, an annular protrusion 152 and a plurality of protrusions 156 disposed on the inner side of the annular protrusion 152 are provided on the upper surface 411 of the ceramic substrate 410. In the circular region Sc located in the center of the upper surface 411 of the ceramic substrate 410, the upper surface of the protrusion 156 is processed such that the envelope surface P1 of the upper surface 156a of the protrusion 156 is a concave surface that is recessed toward the center of the ceramic substrate 410. In the outer region Sout located outside the circular region Sc, the upper surface of the protrusion 156 is processed such that the envelope surface P2 of the upper surface 156a of the protrusion 156 is a horizontal plane (in this embodiment, a plane parallel to the lower surface 113 of the ceramic substrate 110). Furthermore, the term "enveloping surface" refers to a surface whose height difference with the plurality of protrusions 156 is less than 2 μm. In this embodiment, the envelope surface P2 defined in this way is a horizontal plane. In the fifth embodiment, the height H5 of the concave surface of the envelope surface P1 is 20 μm. Furthermore, the height H5 of the convex surface of the envelope surface P2 is defined as the difference in height between the highest and lowest parts of the envelope surface P1.

[0054] In the fifth embodiment, the diameter ϕc of the circular region Sc is 90 mm, which is more than 0.4 times the inner diameter ϕ1 (45 mm) of the cylindrical portion 131 of the shaft 130. As described above, in the fifth embodiment, the envelope surface P1 of the upper surface 156a of the plurality of protrusions 156 in the circular region Sc is a concave surface that convexes downward. In contrast, the envelope surface P2 of the upper surface 156a of the plurality of protrusions 156 in the outer region Sout is a horizontal plane. That is, the curvatures of the envelope surfaces P1 and P2 are different from each other. As shown in FIG10, the diameter ϕc of the circular region Sc is larger than the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130, and larger than the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130 (ϕ1 < ϕ2 < ϕc). Furthermore, similar to the first embodiment, the diameter ϕc of the circular region Sc can be set to be at least 0.4 times the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130. Also, the diameter ϕc of the circular region Sc can be set to be at least 1.5 times the maximum outer diameter ϕ2 of the cylindrical portion 131 of the shaft 130.

[0055] In this embodiment, since annular protrusions 152 are provided on the outer periphery of the ceramic substrate 110, deformation of the outer edge of the wafer 10 can be suppressed when it is adsorbed onto the top surface of the ceramic substrate 110. Furthermore, in the circular region Sc of the top surface 111 of the ceramic substrate 110, the envelope surface P1 of the top surface 156a of the plurality of protrusions 156 becomes a concave surface. Moreover, in the outer region Sout of the top surface 111 of the ceramic substrate 110, the envelope surface P2 of the top surface 156a of the plurality of protrusions 156 becomes a flat (horizontal) plane. Therefore, compared to the case where the envelope surface of the top surface 156a of the plurality of protrusions 156 is a monotonously concave shape, uniform adsorption of the wafer 10 can be achieved on the outer periphery of the entire top surface 111 of the ceramic substrate 110. In particular, even when wafer 10 is warped such that its central region is lower than its outer periphery, the outer periphery of wafer 10 can be quickly adsorbed and stabilized. Therefore, even in the case of wafer 10 warping as described above, there is no concern that wafer 10 will be adsorbed onto the ceramic substrate 110 in a tilted state. Thus, the localized generation of gaps between wafer 10 and the annular protrusion 152 can be suppressed. This suppresses the generation of hot spots on wafer 10 and reduces uneven temperature distribution on wafer 10.

[0056] <Deformation> The above-described embodiments are merely illustrative and can be appropriately modified. For example, the shape and size of the ceramic substrate 110 and the shaft 130 are not limited to the above embodiments and can be appropriately modified. Furthermore, the height, width, and other dimensions, shape of the annular protrusion 152, as well as the surface roughness Ra of its surface, can be appropriately modified. Also, the height of the plurality of protrusions 156, the shape of the surface 156a, and the surface roughness Ra of the surface 156a can be appropriately modified. Furthermore, the diameter ϕc of the circular region Sc can be appropriately modified as long as it is at least 0.4 times the inner diameter ϕ1 of the cylindrical portion 131 of the shaft 130.

[0057] The curvature of the envelope surface P1 of the plurality of protrusions 156 on the upper surface 111 of the circular region Sc on the upper surface 111 of the ceramic substrate 110, and the curvature of the envelope surface P2 of the plurality of protrusions 156 on the upper surface 156 on the outer surface Sout of the upper surface 111 of the ceramic substrate 110, are not limited to the above-described embodiments. For example, as shown in FIG11, the envelope surface P1 of the plurality of protrusions 156 on the upper surface 156 on the circular region Sc may also be an upwardly convex curved surface, and the envelope surface P2 of the plurality of protrusions 156 on the upper surface 156 on the outer surface Sout may also be a downwardly convex curved surface.

[0058] Even in this case, because the annular protrusion 152 is provided on the outer periphery of the ceramic substrate 110, deformation of the outer edge of the wafer 10 can be suppressed when it is adsorbed onto the top surface of the ceramic substrate 110. Furthermore, in the circular region Sc of the top surface 111 of the ceramic substrate 110, the envelope surface P1 of the top surface 156a of the plurality of protrusions 156 becomes an upwardly convex curved surface. This allows for rapid adsorption and stabilization of the wafer 10, even when it is warped such that the central region of the wafer 10 is higher than the outer periphery. Moreover, in the outer region Sout of the top surface 111 of the ceramic substrate 110, the envelope surface P2 of the top surface 156a of the plurality of protrusions 156 becomes a concave surface. This improves the adsorption properties in the outer region of the wafer 10, suppressing the localized generation of gaps between the wafer 10 and the annular protrusion 152. This can suppress the generation of hot spots on wafer 10 and suppress the uneven temperature distribution on wafer 10.

[0059] Furthermore, the shape of the upper surface 156a of the plurality of protrusions 156 does not necessarily have to be circular; it can be any shape. Even in this case, it is preferable to have an area approximately the same as that of a circle with a diameter of 0.1 mm to 5 mm. Also, in the above description, the plurality of protrusions 156 are arranged in a concentric circle configuration, but the present invention is not limited to this configuration. The position and / or number of the protrusions 156 can be appropriately set according to their purpose, function, and purpose. For example, the plurality of protrusions 156 can also be arranged in random positions. In this case, the spacing between the protrusions of the plurality of protrusions 156 is preferably in the range of 1.5 mm to 30 mm.

[0060] In the above embodiments, although the upper surface 111 of the ceramic substrate 110 is a convex or concave curved surface, the present invention is not limited to this form. For example, the upper surface 111 of the ceramic substrate 110 may also be a flat (horizontal) surface (a surface parallel to the lower surface 113 of the ceramic substrate 110).

[0061] In the above embodiments, when the upper surface 111 of the ceramic substrate 110 is a convex curved surface, the first gas flow path 164 disposed inside the ceramic substrate 110 has an opening 164a in the outer region Sout. When the upper surface 411 of the ceramic substrate 410 is a concave curved surface, the second gas flow path 465 disposed inside the ceramic substrate 410 has an opening 465a in the circular region Sc. The present invention is not limited to this form, and the shape of the gas flow path formed inside the ceramic substrate can be appropriately changed. For example, the number and arrangement of openings 164a and 465a can be arbitrarily changed. Furthermore, inside the ceramic substrates 110 and 410, a first gas flow path 164 with an opening 164a in the outer region Sout and a second gas flow path 465 with an opening 465a in the circular region Sc can also be formed. In this case, the first gas flow path 164 and the second gas flow path 465 can be disposed independently or connected to each other.

[0062] Furthermore, the gas flow path 168 extending in the vertical direction 5 may not be formed in the cylindrical portion 131 of the shaft 130. For example, instead of the gas flow path 168, a gas piping may be provided in the hollow area of ​​the cylindrical portion 131 (the area where the power supply line 140 is provided).

[0063] In the above embodiments, although an alloy containing molybdenum, tungsten, or molybdenum and / or tungsten is used as electrode 120, the present invention is not limited to this type. For example, metals or alloys other than molybdenum and tungsten may also be used. Furthermore, electrode 120 is a heater electrode that serves as a heating element, but electrode 120 is not necessarily a heater electrode that serves as a heating element; for example, it may also be a high-frequency electrode.

[0064] In the above embodiment, the substrate holding member 100 includes an electrode 120. However, the present invention is not limited to this embodiment, and the substrate holding member 100 may or may not include an electrode 120. Furthermore, even when the substrate holding member 100 includes an electrode 120, the electrode 120 may not be embedded in the ceramic substrate 110 of the substrate holding member 100. For example, the electrode 120 may be attached to the underside 113 of the ceramic substrate 110.

[0065] The foregoing description uses embodiments and variations of the invention, but the scope of the invention is not limited to those described above. Those skilled in the art will readily apply various modifications or alterations to the embodiments described above. As clearly understood from the claims, such modifications or alterations are also included within the scope of the invention.

[0066] The execution order of each process in the manufacturing method shown in the instruction manual and drawings is not specifically stated. Furthermore, as long as the output of the previous process is not used in the later process, the processes can be executed in any order. For convenience, even if terms such as "first" or "next" are used, it does not mean that the processes must be performed in that order.

[0067] 100, 200, 300, 400, 500: Substrate holding components 110, 410: Ceramic substrate 120: Electrode 130: Shaft 140: Power supply line 152: Annular protrusion 156: Multiple protrusions Sc: Circular area Sout: Outer region

Claims

1. A substrate holding member, characterized in that it comprises: a ceramic substrate having a top surface and a bottom surface facing the top surface in a vertical direction; an electrode embedded in the ceramic substrate or disposed on the bottom surface of the ceramic substrate; and a shaft having a cylindrical portion that engages with the bottom surface of the ceramic substrate; the ceramic substrate comprising: an annular protrusion disposed on the outer periphery of the top surface of the ceramic substrate and protruding upward beyond the top surface of the ceramic substrate; and a plurality of protrusions disposed on the inner side of the annular protrusion on the top surface of the ceramic substrate and protruding upward beyond the top surface of the ceramic substrate; a circular region is provided at the center of the top surface of the ceramic substrate, the circular region being concentric with the ceramic substrate and having a diameter at least 0.4 times the inner diameter of the cylindrical portion; the envelope surface of the top surface of the plurality of protrusions disposed in the circular region, i.e., the first envelope surface, is a plane, and the envelope surface of the top surface of the plurality of protrusions disposed outside the circular region, i.e., the second envelope surface, is a curved surface. Alternatively, the aforementioned first envelope surface is a surface with a first curvature, and the aforementioned second envelope surface is a plane or a surface with a second curvature that is different from the aforementioned first curvature.

2. The substrate holding member of claim 1, wherein the diameter of the aforementioned circular region is less than 1.5 times the maximum outer diameter of the aforementioned cylindrical portion.

3. The substrate holding member of claim 1 or 2, wherein the first envelope surface is a plane and the second envelope surface is an upwardly convex curved surface.

4. The substrate holding member of claim 1 or 2, wherein the first envelope surface is a downwardly convex curved surface and the second envelope surface is an upwardly convex curved surface.

5. The substrate holding member of claim 1 or 2, wherein the first envelope surface is an upwardly convex curved surface and the second envelope surface is a plane.

6. The substrate holding member of claim 1 or 2, wherein the first envelope surface is a plane and the second envelope surface is a downwardly convex curved surface.

7. The substrate holding member of claim 1 or 2, wherein the first envelope surface is a downwardly convex curved surface and the second envelope surface is a plane.

8. The substrate holding member of claim 1 or 2, wherein the first envelope surface is an upwardly convex curved surface and the second envelope surface is a downwardly convex curved surface.

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