Substrate holding member

Abstract

To provide a substrate holding member that can suppress deformation of the outer edge of the substrate and also suppress non-uniformity of adhesion with the substrate.SOLUTION: A substrate holding member 100 has a ceramic base material 110. The top surface 111 of the ceramic base material 110 has an annular ring convex portion 152 disposed around the periphery of the top surface 111 and a plurality of first convex portions 157 disposed inside the ring convex portion 152. The annular convex portion 152 has a first portion 153 and a second portion 154 extending radially inward from the first portion 153.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The present invention relates to a substrate holding member for holding a substrate such as a silicon wafer.

Background Art

[0002] Patent Document 1 discloses an electrostatic chuck for holding a substrate such as a wafer. The electrostatic chuck described in Patent Document 1 includes a base on which a substrate is placed, a plurality of convex portions (protrusions) protruding from the upper surface of the base to support the substrate, and an annular convex portion (seal ring) protruding annularly from the upper surface of the outer peripheral edge portion of the base to support the substrate.

Prior Art Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the electrostatic chuck described in Patent Document 1, the seal ring has an annular shape and the width of the seal ring is constant. Note that the substrate placed on the electrostatic chuck is not necessarily a completely flat disc shape. For example, the entire surface or the outer edge portion of the substrate may be warped or bent. When such a substrate is supported by an annular seal ring having a constant width, the contact area between the seal ring and the substrate may not be uniform over the entire circumferential direction. As a result, local inflow and outflow of gas may occur from a part of the outer edge portion of the substrate, and poor pressure control of the process gas may occur. Further, when a heater is built in the base, heat transfer at the contact surface between the substrate and the seal ring may not be uniform.

[0005] This invention has been made in view of the above circumstances, and aims to provide a substrate holding member that can suppress deformation of the outer edge of the substrate and suppress non-uniformity of adhesion to the substrate. [Means for solving the problem]

[0006] According to a first aspect of the present invention, an upper surface, a lower surface facing the upper surface in the vertical direction , and the side surfaces connecting the upper surface and the lower surface in the vertical direction. It comprises a ceramic substrate having the following characteristics: The aforementioned ceramic substrate is An annular protrusion is arranged on the outer periphery of the upper surface of the ceramic substrate and protrudes above the upper surface of the ceramic substrate, The ceramic substrate comprises a plurality of protrusions arranged inside the annular protrusion on the upper surface of the ceramic substrate and protruding upward from the upper surface of the ceramic substrate, The aforementioned annular protrusion is, The first part extends along the circumference, The first portion comprises a second portion extending radially outward or inward, The central angle β of the second part is 10°≦β dea the law of nature, The distance from the radial center of the ceramic substrate to the side surface is constant throughout the circumferential direction. A substrate holding member is provided, characterized by the following.

[0007] According to a second aspect of the present invention, the ceramic substrate comprises an upper surface, a lower surface facing the upper surface in the vertical direction, and a side surface connecting the upper surface and the lower surface in the vertical direction. The aforementioned ceramic substrate is An annular protrusion is arranged on the outer periphery of the upper surface of the ceramic substrate and protrudes above the upper surface of the ceramic substrate, The ceramic substrate comprises a plurality of first protrusions arranged inside the annular protrusion on the upper surface of the ceramic substrate and protruding above the upper surface of the ceramic substrate, The annular protrusion has a plurality of periodic portions that extend in a direction different from the circumferential direction at predetermined intervals in the circumferential direction, The ceramic substrate diameter A substrate holding member is provided, characterized in that the distance from the center of the direction to the side surface is constant throughout the entire circumferential direction. [Effects of the Invention]

[0008] In the first embodiment described above, 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 toward the upper surface of the ceramic substrate. However, if the annular protrusion has a perfectly circular shape, the substrate and the annular protrusion may not adhere uniformly. In contrast, in the first embodiment described above, a second portion is formed on the annular protrusion. This increases the contact area between the substrate and the annular protrusion, thereby improving the non-uniformity of adhesion between the substrate and the annular protrusion.

[0009] In the second embodiment described above, 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 toward the upper surface of the ceramic substrate. However, as described above, if the annular protrusion has a perfectly circular annular shape, the substrate and the annular protrusion may not adhere uniformly. In contrast, in the second embodiment described above, the annular protrusion has multiple periodic portions that extend in a direction different from the circumferential direction at predetermined intervals in the circumferential direction. Therefore, the contact area between the substrate and the annular protrusion can be increased, and the non-uniformity of adhesion between the substrate and the annular protrusion can be improved. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram illustrating the substrate holding member 100. [Figure 2] Figure 2 is a schematic diagram of electrode 120. [Figure 3] Figure 3 is a schematic diagram showing a portion of the substrate holding member 100. [Figure 4] (a)-(e) are diagrams showing the process of manufacturing the ceramic base material 110. [Figure 5] (a)-(d) are diagrams showing the process of another manufacturing method of the ceramic base material 110. [Figure 6] FIG. 6 is a diagram corresponding to FIG. 3 of the substrate holding member 100A of the comparative example. [Figure 7] FIG. 7 is a diagram corresponding to FIG. 3 of the substrate holding member 100 of Example 2. [Figure 8] FIG. 8 is a diagram corresponding to FIG. 3 of the substrate holding member 100 of Example 3. [Figure 9] FIG. 9 is a diagram corresponding to FIG. 3 of the substrate holding member 100 of Example 4. [Figure 10] FIG. 10 is a diagram corresponding to FIG. 3 of the substrate holding member 100 of Example 5. [Figure 11] FIG. 11 is a schematic explanatory diagram of the electrostatic adsorption electrode 124. [Figure 12] FIG. 12 is a schematic external view of the substrate holding member 100 having the shaft 130. [Figure 13] This is a table summarizing the results of Examples 1-6 and the comparative example. [Figure 14] This is a flowchart showing the manufacturing method of the substrate holding member 100.

Embodiments for Carrying Out the Invention

[0011] <Substrate Holding Member 100> The substrate holding member 100 according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. The substrate holding member 100 according to this embodiment is a ceramic heater used for heating a semiconductor wafer such as a silicon wafer (hereinafter simply referred to as wafer 10). In the following description, the vertical direction 5 is defined based on the state in which the substrate holding member 100 is installed so as to be usable (the state of FIG. 1). As shown in FIG. 1, the substrate holding member 100 according to this embodiment includes a ceramic base material 110, an electrode 120, a shaft 130, and a power supply line 140.

[0012] The ceramic substrate 110 is a circular, plate-shaped component with a diameter of 12 inches (approximately 300 mm), and the wafer 10 to be heated is placed on top of the ceramic substrate 110. As shown in Figure 1, the upper surface 111 of the ceramic substrate 110 is provided with an annular protrusion 152 (hereinafter simply referred to as the annular protrusion 152) and a plurality of protrusions 156. A first gas channel 164, described later, is formed inside the ceramic substrate 110. The ceramic substrate 110 can be formed from, for example, a ceramic sintered body such as aluminum nitride, silicon carbide, alumina, or silicon nitride.

[0013] As shown in Figure 1, the annular projection 152 is a substantially annular projection located on the outer periphery (outer edge) of the upper surface 111 of the ceramic substrate 110, and protrudes upward from the upper surface 111. As shown in Figure 1, when the wafer 10 is placed on the ceramic substrate 110, the upper surface 152a of the annular projection 152 abuts against the lower surface of the wafer 10. In other words, when the wafer 10 is placed on the ceramic substrate 110, the annular projection 152 is positioned to overlap with the wafer 10 in the vertical direction 5. The annular projection 152 includes a first portion 153 extending along the circumferential direction and a second portion 154 located radially inward from the first portion 153. The number of second portions 154 provided on the annular projection 152 may be one or two or more. In this embodiment, the annular projection 152 is provided with three second portions 154.

[0014] Multiple protrusions 156 are provided inside the annular protrusion 152 on the upper surface 111 of the ceramic substrate 110. Each of the multiple protrusions 156 has a cylindrical shape. The multiple protrusions 156 are arranged in a square such that each is positioned at the vertex of the square. The position and / or number of the protrusions 156 are set as appropriate according to the application, action, and function. In Figure 1, all of the multiple protrusions 156 are located inside the annular protrusion 152. In this specification, the multiple protrusions 156 located inside the annular protrusion 152 are referred to as the first protrusions 157. Also, the multiple protrusions 156 located outside the annular protrusion 152 are referred to as the second protrusions 158 (see Figure 10).

[0015] The height of the annular projection 152 (length in the vertical direction 5 from the upper surface 111) can be in the range of 5 μm to 2 mm. Similarly, the heights of the multiple projections 156 can also be in the range of 5 μm to 2 mm. As shown in Figure 2, the height of the annular projection 152 can be the same as the height of the multiple projections 156. For example, in this embodiment, the heights of both the annular projection 152 and the multiple projections 156 are 150 μm. Furthermore, the height position in the vertical direction 5 of the upper surface 152a of the annular projection 152 and the upper surface 156a of the multiple projections 156 may be the same. Alternatively, the height position in the vertical direction 5 of the upper surface 152a of the annular projection 152 may be about 10 μm lower or higher than the height position of the upper surface 156a of the multiple projections 156. In this case, the height position 5 in the vertical direction of the upper surface 152a of the annular projection 152 from the upper surface 111 of the ceramic substrate 110 may be different from the height position 5 in the vertical direction of the upper surfaces 156a of the multiple projections 156.

[0016] The first portion 153 and the second portion 154 of the annular protrusion 152 are preferably of a constant width, which can be 0.1 mm to 10 mm. The surface roughness Ra of the upper surface 152a of the annular protrusion 152 can be 1.6 μm or less. The surface roughness Ra of the upper surfaces 156a of the multiple protrusions 156 can be 1.6 μm or less. The surface roughness Ra of the upper surface 152a of the annular protrusion 152 and the upper surfaces 156a of the multiple 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 first portion 153 and the second portion 154 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 surfaces 156a of the multiple protrusions 156 is 0.4 μm.

[0017] The upper surfaces 156a of the multiple protrusions 156 are preferably circular with a diameter of 0.1 mm to 5 mm. The spacing between the multiple protrusions 156 can be in the range of 1.5 mm to 30 mm. For example, in this embodiment, the upper surfaces 156a of the multiple protrusions 156 are circular with a diameter of 2 mm, and the spacing between the multiple protrusions 156 is 10 mm.

[0018] As shown in Figure 1, an opening 164a of the first gas channel 164 is provided on the upper surface 111. The first gas channel 164 is a gas channel with an opening 164a and is formed inside the ceramic substrate 110. The first gas channel 164 extends downward from the opening 164a. As will be described later, the lower end of the first gas channel 164 is joined to the upper end of the second gas channel 168, which is formed inside the shaft 130.

[0019] The first gas channel 164 can be used as a channel for supplying 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, it can supply heat transfer gas for heat transfer between the wafer 10 and the ceramic substrate 110. As the heat transfer gas, for example, an inert gas such as helium or argon, or nitrogen gas can be used. The heat transfer gas is supplied through the first gas channel 164 at a pressure set within the range of 100 Pa to 40000 Pa. In addition, if 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 exhausted through the first gas channel 164. In this case, the differential pressure between the pressure outside the gap and the pressure inside the gap can be adjusted by adjusting the exhaust pressure. This makes it possible to adsorb the wafer 10 toward the upper surface of the ceramic substrate 110.

[0020] As shown in Figure 1, an electrode 120 (an example of a heating element of the present invention) is embedded inside the ceramic substrate 110. As shown in Figure 2, the electrode 120 is a strip-shaped metal mesh or foil. The outer diameter of the electrode 120 is 298 mm. The electrode 120 is not exposed from the side of the ceramic substrate 110. A terminal portion 121, which is connected to a power supply line 140 (see Figure 1), is provided approximately in the center of the electrode 120. The electrode 120 is formed from a heat-resistant metal (high melting point metal) such as a mesh or foil woven from wire of tungsten (W), molybdenum (Mo), or an alloy containing molybdenum and / or tungsten. The purity of the tungsten and molybdenum is preferably 99% or higher. The thickness of the electrode 120 is 0.15 mm or less. Furthermore, from the viewpoint of increasing the resistance of the electrode 120 and reducing the current consumption of the substrate holding member 100, it is preferable to set the wire diameter to 0.1 mm or less and the thickness of the electrode 120 to 0.1 mm or less. In addition, the width of the strip-shaped electrode 120 is preferably 2.5 mm to 20 mm, and more preferably 5 mm to 15 mm. In this embodiment, the electrode 120 is cut into the shape shown in Figure 2, but the shape of the electrode 120 is not limited to this and can be changed as appropriate. Furthermore, in addition to the electrode 120, or in place of the electrode 120, at least one of the following may be embedded inside the ceramic substrate 110: an electrostatic chuck electrode for attracting the wafer 10 to the upper surface 111 by Coulomb force, and a plasma electrode for generating plasma above the ceramic substrate 110.

[0021] As shown in Figure 1, a shaft 130 is connected to the lower surface 113 of the ceramic substrate 110. The shaft 130 has a hollow, substantially cylindrical cylindrical portion 131 and a large-diameter portion 132 (see Figure 12) located below the cylindrical portion 131. The large-diameter portion 132 has a larger diameter than the cylindrical portion 131. In the following description, the longitudinal direction of the cylindrical portion 131 is defined as the longitudinal direction 6 of the shaft 130. As shown in Figure 1, in the usage state of the substrate holding member 100, the longitudinal direction 6 of the shaft 130 is parallel to the vertical direction 5.

[0022] Furthermore, a protrusion 114 (hereinafter referred to as the joining protrusion 114) for joining with the shaft 130 can be provided on the lower surface 113 of the ceramic substrate 110 (see Figure 12). The shape of the joining protrusion 114 is preferably the same as the shape of the upper surface 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 (height from the lower surface 113) should be 2 mm or more, and preferably 5 mm or more. There is no particular upper limit on the height, but considering the 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 100. The surface roughness Ra of the lower surface of the joining protrusion 114 should 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, and more preferably 0.2 μm or less.

[0023] The upper surface of the cylindrical portion 131 is fixed to the lower surface 113 of the ceramic base material 110 (or the lower surface of the joining projection 114 if one is provided). The shaft 130 may be formed from a ceramic sintered body such as aluminum nitride, silicon carbide, alumina, or silicon nitride, similar to the ceramic base material 110. Alternatively, to improve heat insulation, it may be formed from a material with lower thermal conductivity than the ceramic base material 110. Furthermore, an enlarged diameter portion similar to the large diameter portion 132 provided below the cylindrical portion 131 may be provided on the upper surface of the cylindrical portion 131.

[0024] As shown in Figure 1, 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 inside the inner diameter). A power supply line 140 for supplying power to the electrode 120 is arranged 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 2) located in the center of the electrode 120. The power supply line 140 is connected to a heater power supply (not shown). As a result, power is supplied to the electrode 120 via the power supply line 140.

[0025] Furthermore, as shown in Figure 1, a second gas passage 168 extending in the vertical direction 5 is formed in the cylindrical portion 131 of the shaft 130. As described above, the upper end of the second gas passage 168 is connected to the lower end of the first gas passage 164.

[0026] Next, the manufacturing method of the substrate holding member 100 will be described. In the following description, the case in which the ceramic substrate 110 and the shaft 130 are made of aluminum nitride will be used as an example.

[0027] First, the method for manufacturing the ceramic substrate 110 will be described. As shown in Figure 4(a), granulated powder P, mainly composed of aluminum nitride (AlN) powder, is placed in a carbon bed mold 501 and pre-pressed with a punch 502. Preferably, the granulated powder P contains 5 wt% or less of a sintering aid (for example, Y2O3). Next, as shown in Figure 4(b), electrodes 120 cut to a predetermined shape are placed on top of the pre-pressed granulated powder P. The electrodes 120 are positioned parallel to the surface perpendicular to the pressing direction (the bottom surface of the bed mold 501). At this time, pellets of W or Mo may be embedded at the terminal 121 (see Figure 2) of the electrode 120.

[0028] As shown in Figure 4(c), granulated powder P is further added to the bed mold 501 so as to cover the electrode 120, and then pressed and molded with a punch 502. Next, as shown in Figure 4(d), the granulated powder P with the electrode 120 embedded is fired in the pressed state. The pressure applied during firing is preferably 1 MPa or more. It is also preferable to fire at a temperature of 1800°C or higher. Next, as shown in Figure 4(e), a blind hole is drilled up to the electrode 120 in order to form the terminal 121. If a pellet is embedded, a blind hole drilling up to the pellet is sufficient. Furthermore, a through hole is formed which will become part of the first gas flow path 164. This makes it possible to produce a ceramic substrate 110 with the first gas flow path 164 formed inside. In this case, a predetermined escape route is provided in advance so that the electrode 120 is not exposed from the first gas flow path 164.

[0029] Furthermore, the ceramic substrate 110 can also be manufactured by the following method. As shown in Figure 5(a), a binder is added to granulated aluminum nitride powder P and CIP molding is performed, and the resulting disc is processed to produce an aluminum nitride molded body 510. Next, as shown in Figure 5(b), the molded body 510 is degreased to remove the binder.

[0030] As shown in Figure 5(c), a recess 511 for embedding the electrode 120 is formed in the degreased molded body 510. The electrode 120 is placed in the recess 511 of the molded body 510, and another molded body 510 is stacked on top. The recess 511 may be formed in the molded body 510 in advance. Next, as shown in Figure 5(d), the molded bodies 510 stacked with the electrode 120 sandwiched in between are fired while pressed to produce a fired body. The pressure applied during firing is preferably 1 MPa or more. It is also preferable to fire at a temperature of 1800°C or higher. The process after producing the fired body is the same as the process described above, so the explanation is omitted.

[0031] The upper surface 111 of the ceramic substrate 110 formed in this manner is ground and polished. Furthermore, sandblasting is performed on the upper surface 111 to form a plurality of protrusions 156 and annular protrusions 152 on the upper surface 111. Although sandblasting is preferred as the processing method for forming the plurality of protrusions 156 and annular protrusions 152, other processing methods can also be used. The lower surface 113 of the ceramic substrate 110 may be provided with joining protrusions 114 that protrude from the lower surface 113 (see Figure 12).

[0032] Next, the manufacturing method of the shaft 130 and the method of joining the shaft 130 to the ceramic substrate 110 will be described. First, granulated aluminum nitride powder P with several wt% binder added is molded under hydrostatic pressure (approximately 1 MPa) to process the molded body into a predetermined shape. The outer diameter of the shaft 130 is approximately 30 mm to 100 mm. A flange portion 133 having a diameter larger than the outer diameter of the cylindrical portion 131 may be provided at the end face of the cylindrical portion 131 of the shaft 130 (see Figure 12). The length of the cylindrical portion 131 can be, for example, 50 mm to 500 mm. At this time, a through hole that will become a second gas passage 168 is formed in the molded body. After that, the molded body is fired in a nitrogen atmosphere. For example, it is fired at a temperature of 1900°C for 2 hours. Then, the shaft 130 is formed by processing the sintered body into a predetermined shape after firing. The upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic substrate 110 can be fixed by diffusion bonding at a temperature of 1600°C or higher and a uniaxial pressure of 1 MPa 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 also be bonded using a bonding agent. As a bonding agent, for example, an AlN bonding paste with 10 wt% Y2O3 added can be used. For example, the above AlN bonding paste can be applied to the interface between the upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic substrate 110 to a thickness of 15 μm, and the bonding can be achieved by heating at a temperature of 1700°C for 1 hour while applying a force of 5 kPa in a direction perpendicular to the upper surface 111 (the longitudinal direction of the shaft 130 6). Alternatively, the upper surface of the cylindrical portion 131 and the lower surface 113 of the ceramic base material 110 can be fixed together by screwing, brazing, or the like. [Examples]

[0033] The present invention will be further described below with reference to examples and comparative examples. However, the present invention is not limited to the examples and comparative examples described below.

[0034] [Comparative Example] A comparative example substrate holding member 100A (see Figure 6) will be described. In the comparative example, a ceramic substrate 110 with a diameter of 300 mm and a thickness of 20 mm was fabricated using the above-described manufacturing method, with aluminum nitride (AlN) to which 5 wt% of a sintering aid (Y2O3) was added as the raw material. For the electrode 120, a molybdenum mesh (wire diameter 0.1 mm, mesh size #50, plain weave) was cut into the shape shown in Figure 2 and embedded in the ceramic substrate 110. An annular projection 152 with an inner diameter of 292 mm, an outer diameter of 298 mm, a width of 3 mm, and a height of 150 μm from the upper surface 111 was formed on the upper surface 111 of the ceramic substrate 110. As shown in Figure 6, in the comparative example substrate holding member 100A, the second portion 154 is not formed on the annular projection 152. Furthermore, multiple cylindrical protrusions 156 (first protrusion 157) with a diameter of 2 mm and a height of 150 μm from the top surface 111 were formed on the upper surface 111 of the ceramic substrate 110. As described above, the multiple protrusions 156 were arranged in a square, and the distance between each protrusion was 10 mm. Thus, in the comparative example substrate holding member 100A, the height of the annular protrusion 152 is 150 μm, and the height of the multiple protrusions 156 is 150 μm. In other words, the height of the annular protrusion 152 and the height of the multiple protrusions 156 are the same. To put it another way, the vertical position 5 (height position) of the upper surface 152a of the annular protrusion 152 and the vertical position 5 of the upper surface 156a of the protrusion 156 are the same. The surface roughness Ra of the upper surface 152a of the annular protrusion 152 and the upper surface 156a of the protrusion 156 were both set to 0.4 μm.

[0035] The diameter of the opening 164a of the first gas flow path 164 is 3 mm. The center of the opening 164a is located 30 mm from the center of the ceramic substrate 110.

[0036] A substrate holding member 100A of this shape was installed in the process chamber. Argon gas was supplied into the process chamber as the process gas at a pressure of 26600 Pa (200 Torr). Furthermore, the argon gas was adjusted to a pressure of 6650 Pa (50 Torr) through the first gas flow path 164.

[0037] The temperature of the substrate holding member 100A was then evaluated using the following procedure. First, a silicon wafer for temperature evaluation was placed on the ceramic substrate 110, and an external power supply (not shown) was connected to the electrode 120 of the substrate holding member 100. The output power of the external power supply was then adjusted so that the temperature of the upper surface of the silicon wafer was approximately 400°C in a steady state. The pressures of the process gas and the argon gas used as a heat transfer gas were then adjusted to the above pressure. Subsequently, the temperature distribution of the silicon wafer for temperature evaluation, in a 298 mm diameter region excluding the 1 mm region from the outer edge, was measured using an infrared camera. The difference between the highest and lowest temperatures in the 298 mm diameter region of the silicon wafer for temperature evaluation was defined as the temperature difference Δ. In addition, it was evaluated whether a localized high-temperature area (heat spot) occurred at a position overlapping the annular protrusion 152 in the vertical direction on the silicon wafer for temperature evaluation. A heat spot was determined to have occurred if there was a region that was 3.0°C or more hotter than the average temperature of the silicon wafer for temperature evaluation. The silicon wafer used for temperature evaluation was a 300 mm diameter silicon wafer with a 30 μm thick blackbody film coated on its upper surface. A blackbody film is a film with an emissivity (radiative efficiency) of 90% or more, and can be formed, for example, by coating with a blackbody paint mainly composed of carbon nanotubes. In the comparative example, the gas flow rate of argon gas flowing through the first gas channel 164 was 2.1 sccm. The gas flow rate of argon gas was controlled by a mass flow meter. When the temperature distribution of the silicon wafer used for temperature evaluation was evaluated, the temperature difference Δ was 3.8°C. In addition, a heat spot occurred in a part of the annular region of the silicon wafer used for temperature evaluation that overlapped with the annular protrusion 152 in the vertical direction.

[0038] [Example 1] As shown in Figures 1 and 3, the substrate holding member 100 of Example 1 has the same shape as the substrate holding member 100A of the Comparative Example, except that a substantially rectangular second portion 154 is formed on a part of the annular protrusion 152. The second portion 154 is provided to cover the portion where a heat spot occurred in the Comparative Example.

[0039] In Example 1, the argon gas was adjusted to the same pressure as in the Comparative Example. In Example 1, the gas flow rate of the argon gas flowing through the first gas channel 164 was 0.8 sccm, which was a flow rate that did not pose any problems for pressure control. The gas flow rate of the argon gas was adjusted using a mass flow meter. When the temperature distribution of the silicon wafer used for temperature evaluation was evaluated, the temperature difference Δ was 2.5°C. Furthermore, no heat spots were observed in the annular region of the silicon wafer used for temperature evaluation that overlapped with the annular protrusion 152 in the vertical direction.

[0040] [Example 2] The substrate holding member 100 of Example 2 is the same as the substrate holding member 100 of Example 1, except that the shape of the annular protrusion 152 is different. As shown in Figure 7, the annular protrusion 152 of the substrate holding member 100 of Example 2 has second portions 154 arranged periodically in the circumferential direction. The circumferential length of the first portion 153 and the circumferential length of the second portion 154 are approximately the same. In other words, in the annular protrusion 152, the central angle α of the first portion 153 and the central angle β of the second portion are the same. To put it another way, the annular protrusion 152 has periodic portions 155 of a rectangular waveform arranged periodically in the circumferential direction. The argon gas was also adjusted to the same pressure as in Example 1. In Example 2, the gas flow rate of the argon gas flowing through the first gas channel 164 was 1.1 sccm. When the temperature distribution of the silicon wafer for temperature evaluation was evaluated, the temperature difference Δ was 2.1℃. Furthermore, no heat spots were observed in the region of the silicon wafer used for temperature evaluation that overlapped with the annular protrusion 152 in the vertical direction.

[0041] [Example 3] The substrate holding member 100 of Example 3 is the same as the substrate holding member 100 of Example 1, except that the shape of the annular protrusion 152 and the arrangement of the multiple protrusions 156 are different. As shown in Figure 8, the annular protrusion 152 of Example 3 has periodic portions 155 of a waveform that are periodically arranged in the circumferential direction. The periodic portions 155 are repeated every 6° central angle. The diameter of the part of the waveform annular protrusion 152 furthest from the center is 298 mm, and the diameter of the part closest to the center is 288 mm. The width of the annular protrusion 152 is 2 mm. The multiple protrusions 156 (first protrusions 157) are arranged concentrically. The outermost protrusions 157a located on the outermost periphery of the multiple first protrusions 157 are arranged every 6° central angle.

[0042] In Example 3, the argon gas was adjusted to the same pressure as in Example 1. In Example 3, the gas flow rate of the argon gas flowing through the first gas channel 164 was 0.8 sccm. When the temperature distribution of the silicon wafer used for temperature evaluation was evaluated, the temperature difference Δ was 2.0°C. Furthermore, no heat spots were observed in the annular region of the silicon wafer used for temperature evaluation that overlapped with the annular protrusion 152 in the vertical direction.

[0043] [Example 4] The substrate holding member 100 of Example 4 is the same as the substrate holding member 100 of Example 3, except that the shape of the annular protrusion 152 is different. As shown in Figure 9, the annular protrusion 152 of Example 4 has periodic portions 155 that are arranged periodically in the circumferential direction. Each periodic portion 155 has an S-shaped portion and an inverted S-shaped portion which is a mirror image of the S-shaped portion. Because each periodic portion 155 has such a shape, as shown in Figure 9, the annular protrusion 152 intersects with a virtual line (straight line) crossing the radial direction at multiple points. The periodic portion 155b is repeated every 6° central angle. Similar to Example 3, the diameter of the part of the annular protrusion 152 furthest from the center is 298 mm, and the diameter of the part closest to the center is 288 mm. The width of the annular protrusion 152 is 2 mm. Similar to Example 3, the multiple protrusions 156 (first protrusion 157) are arranged concentrically. The outermost protrusions 157a located on the outermost periphery of the multiple protrusions 157 are arranged at intervals of 6° central angle.

[0044] In Example 4, the argon gas was adjusted to the same pressure as in Example 1. In Example 4, the gas flow rate of the argon gas flowing through the first gas channel 164 was 1.3 sccm. When the temperature distribution of the silicon wafer used for temperature evaluation was evaluated, the temperature difference Δ was 2.3°C. Furthermore, no heat spots were observed in the annular region of the silicon wafer used for temperature evaluation that overlapped with the annular protrusion 152 in the vertical direction.

[0045] [Example 5] The substrate holding member 100 of Example 5 is the same as the substrate holding member 100 of Example 3, except that the shape of the annular protrusion 152 and the arrangement of the multiple protrusions 156 are different. As shown in Figure 10, the annular protrusion 152 of Example 5 has triangular wave-shaped periodic portions 155 that are periodically arranged in the circumferential direction. The periodic portions 155 are repeated every 6° central angle. The diameter of the part of the triangular wave-shaped annular protrusion 152 furthest from the center is 298 mm, and the diameter of the part closest to the center is 288 mm. The width of the annular protrusion 152 is 2 mm. The multiple protrusions 156 have multiple first protrusions 157 arranged inside the annular protrusion 152 and multiple second protrusions 158 arranged outside the annular protrusion 152. The multiple first protrusions 157 are arranged concentrically. The outermost protrusions 157a located on the outermost periphery of the multiple first protrusions 157 are arranged every 6° central angle. Similarly, multiple second protrusions 158 are also arranged at 6° intervals along their central angle.

[0046] In Example 5, the argon gas was adjusted to the same pressure as in Example 1. In Example 5, the gas flow rate of the argon gas flowing through the first gas channel 164 was 0.8 sccm. When the temperature distribution of the silicon wafer used for temperature evaluation was evaluated, the temperature difference Δ was 1.9°C. Furthermore, no heat spots were observed in the annular region of the silicon wafer used for temperature evaluation that overlapped with the annular protrusion 152 in the vertical direction.

[0047] [Example 6] The substrate holding member 100 of Example 6 is the same as the substrate holding member 100 of Example 3, except that the height of the annular protrusion 152 is 30 μm, in addition to the electrode 120 shown in Figure 2, the electrostatic adsorption electrode 124 shown in Figure 11 is embedded at a depth of 1 mm from the upper surface of the ceramic substrate 110, and the height of the annular protrusion 152 and the multiple protrusions 156 (first protrusion 157) is 15 μm. As shown in Figure 11, the electrostatic adsorption electrode 124 consists of two semicircular electrodes 124a and 124b arranged facing each other with a predetermined distance (5 mm) between them, and has an overall substantially circular shape. The outer diameter of the electrostatic adsorption electrode 124 is 294 mm. In Example 6, a voltage of +500 V was applied to electrode 124a and -500 V to electrode 124b, and the wafer 10 was electrostatically adsorbed. In Example 6, approximately 50W of heater power was supplied to the substrate holding member 100 by a heater power supply (not shown). In Example 6, nitrogen gas was supplied to the process chamber as a process gas at a pressure of 10 Pa. Helium gas was flowed through the first gas channel 164. The pressure of the helium gas flowing through the first gas channel 164 was adjusted to 665 Pa (5 Torr). In Example 6, the gas flow rate of the helium gas flowing through the first gas channel 164 was 0.6 sccm. When the temperature distribution of the silicon wafer used for temperature evaluation was evaluated, the temperature difference Δ was 1.0°C. Furthermore, no heat spots were observed in the annular region of the silicon wafer used for temperature evaluation that overlapped with the annular protrusion 152 in the vertical direction.

[0048] <Summary of Examples and Comparative Examples> Figure 13 shows a table summarizing the results of Examples 1 to 6 and the comparative examples described above.

[0049] As described above, the substrate holding member 100 of Examples 1 to 6 is equipped with a first gas channel 164 having an opening 164a that opens inside the annular protrusion 152. This allows the flow rate and / or pressure of the gas flowing through the first gas channel 164 to be adjusted. For example, as in Examples 1 to 5, the pressure in the gap surrounded by the upper surface 111 of the ceramic substrate 110, the annular protrusion 152, and the wafer 10 (6650 Pa in Examples 1 to 5) can be set lower than the pressure of the process gas in the process chamber (26600 Pa in Examples 1 to 5). Since the pressure in the gap surrounded by the upper surface 111 of the substrate holding member 110, the annular protrusion 152, and the wafer 10 can be lower than the pressure of the process gas in the process chamber, the wafer 10 can be held by adsorption toward the upper surface 111 of the ceramic substrate 110 due to the difference in pressure. Alternatively, as in Example 6, if the substrate holding member 100 is equipped with an electrostatic adsorption electrode 124, the wafer 10 can be held by adsorbing it toward the upper surface 111 of the ceramic substrate 110 using electrostatic force.

[0050] Here, we consider the case where, as in the comparative example, the annular projection 152 does not have a second portion 154 or a periodic portion 155. As in the comparative example, when the annular projection 152 has an annular shape, the wafer 10 and the annular projection 152 may not adhere uniformly due to the structure of the substrate holding member 100, etc. The structure of the substrate holding member 100 that may be related to the non-uniform adhesion between the wafer 10 and the annular projection 152 includes the pattern of the electrode 120, the shape of the electrostatic adsorption electrode 124, the environment of the vacuum container on which the substrate holding member 100 is placed, the position of the exhaust port, and the arrangement of the lift pins for placing the wafer 10. When the wafer 10 and the annular projection 152 do not adhere uniformly, local gas leakage may occur between the space defined by the wafer 10 and the annular projection 152 (back gas space) and the process chamber. Furthermore, the non-uniform contact between the wafer 10 and the annular protrusion 152 may lead to uneven temperature and uneven flatness of the wafer 10. Therefore, in the comparative example, it is believed that a heat spot region occurred along the annular protrusion 152 when the temperature distribution of the silicon wafer used for temperature evaluation was assessed.

[0051] In contrast, in Example 1, the second portion 154 is formed to avoid the area where a heat spot occurred on the annular protrusion 152 in the comparative example. This increases the contact area between the wafer 10 and the annular protrusion 152, improving the adhesion between the wafer 10 and the annular protrusion 152. As a result, localized gas leakage as described above can be suppressed, and uneven temperature and uneven flatness of the wafer 10 caused by gas leakage can be suppressed.

[0052] Furthermore, in Examples 2 to 6, the annular protrusion 152 has a periodic portion 155 that is periodically provided around its entire circumference. This increases the contact area between the wafer 10 and the annular protrusion 152, thereby improving the adhesion between the wafer 10 and the annular protrusion 152. As a result, localized gas leakage as described above can be suppressed, and non-uniformity in the temperature and flatness of the wafer 10 caused by gas leakage can be suppressed.

[0053] <Effects of the Embodiment> In the above embodiments and examples 1 and 2, the substrate holding member 100 comprises a ceramic substrate 110. The upper surface 111 of the ceramic substrate 110 is provided with an annular projection 152 positioned on the outer periphery of the upper surface 111 and projecting upward from the upper surface 111, and a plurality of projections 156 positioned inside the annular projection 152 and projecting upward from the upper surface 111. The annular projection 152 has a first portion 153 extending along the circumferential direction and a second portion 154 located radially inward from the first portion 153. The second portion 154 has a portion extending radially inward from the first portion 153. The central angle β of the second portion 154 is β ≥ 10°. If there are multiple second portions 154, the central angle β of the second portion 154 is the sum of the central angles of the multiple second portions 154.

[0054] Since an annular projection 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 the wafer 10 is adsorbed toward the upper surface of the ceramic substrate 110. However, as described above, if the annular projection 152 has a perfectly circular annular shape, the wafer 10 and the annular projection 152 may not adhere uniformly due to the structure of the substrate holding member 100, etc. In contrast to this, in the above embodiment and examples 1 and 2, a second portion 154 is formed. This increases the contact area between the wafer 10 and the annular projection 152, improving the non-uniformity of adhesion between the wafer 10 and the annular projection 152. As a result, localized gas leakage as described above can be suppressed, and non-uniformity of the wafer 10 temperature and non-uniformity of the wafer 10 flatness caused by gas leakage can be suppressed.

[0055] As shown in Figure 14, when manufacturing the substrate holding member 100, the position at which the narrow portion 153 should be formed on the annular protrusion 152 can be determined as follows.

[0056] As in the comparative example described above, first, a substrate holding member 100A without the second portion 154 is prepared (S10), and the temperature distribution of the silicon wafer for temperature evaluation is measured while the silicon wafer for temperature evaluation is held in the substrate holding member 100A (Figure 13: S20). Based on the measured temperature distribution, the location of the heat spot on the annular protrusion 152 is identified (S30). Then, for example, as in Example 1, the second portion 154 is formed in the region of the annular protrusion 152 corresponding to the location of the heat spot (S40). This makes it possible to suppress the generation of heat spots and make the temperature distribution of the wafer 10 uniform.

[0057] In the above embodiments 2 to 6, the substrate holding member 100 also comprises a ceramic substrate 110. The upper surface 111 of the ceramic substrate 110 is provided with an annular projection 152 positioned on the outer periphery of the upper surface 111 and projecting upward from the upper surface 111, and a plurality of projections 156 positioned inside the annular projection 152 and projecting upward from the upper surface 111. The annular projection 152 has a plurality of periodic portions 155 extending in a direction different from the circumferential direction at predetermined intervals in the circumferential direction. Therefore, as described above, the contact area between the wafer 10 and the annular projection 152 can be increased, improving the non-uniformity of the adhesion between the wafer 10 and the annular projection 152. As a result, localized gas leakage as described above can be suppressed, and non-uniformity of the wafer 10 temperature and non-uniformity of the wafer 10 flatness caused by gas leakage can be suppressed.

[0058] Furthermore, the wafer 10 may have a curved shape rather than a flat shape. In such cases, with an annular projection 152 having an annular shape like the comparative example, it becomes difficult for the upper surface 152a of the annular projection 152 and the wafer 10 to adhere uniformly over the entire area of ​​the upper surface 152a of the annular projection 152. In particular, since the wafer 10 is prone to bending at its outer edge, with an annular projection 152 having an annular shape where the suction force acts only in the circumferential direction, like the comparative example, there was a high risk that the upper surface 152a of the annular projection 152 and the wafer 10 would not adhere uniformly, causing the wafer to open up. In contrast, as in Examples 2 to 6, when the annular projection 152 has a periodic portion 155 that is periodically provided around its entire circumference, the suction force at the outer edge of the wafer 10 can be ensured even with wafers 10 that have various curvatures. As a result, temperature inconsistencies and flatness inconsistencies of the wafer 10 caused by gas leakage can be suppressed.

[0059] In the above embodiments 3 to 6, among the first protrusions 157 arranged inside the annular protrusion 152, the multiple outermost protrusions 157a located on the radially outermost side are arranged in a circular pattern with the same period as the periodic portion 155. By relating the periodicity of the periodic portion 155 of the annular protrusion 152 with the periodicity of the arrangement of the multiple first protrusions 157 (outermost protrusions 157a), the effect of correcting the flatness of the outer edge of the wafer 10 can be improved. As a result, temperature non-uniformity and non-uniformity of the flatness of the wafer 10 caused by gas leakage can be further suppressed.

[0060] In Example 5, the ceramic substrate 110 is provided with a plurality of second protrusions 158 located outside the annular protrusion 152. By providing the second protrusions 158 outside the annular protrusion 152 in this way, the effect of correcting the flatness of the outer edge of the wafer 10 can be enhanced. As a result, temperature non-uniformity and non-uniformity of the wafer 10 flatness caused by gas leakage can be further suppressed.

[0061] In Example 4, the periodic portion 155 of the annular protrusion 152 has a shape (labyrinth shape) that crosses multiple imaginary lines extending radially from the center of the annular protrusion 152. This increases the contact area between the annular protrusion 152 and the outer edge of the wafer 10. As a result, it is possible to suppress temperature inconsistencies and flatness inconsistencies of the wafer 10 caused by gas leakage.

[0062] In Example 6, the ceramic substrate 110 includes an electrostatic adsorption electrode 124. In this case, an electrostatic adsorption force acts between the wafer 10 and the electrostatic adsorption electrode 124, allowing the wafer 10 to be adsorbed. Furthermore, by shaping the annular protrusion 152 as in the above embodiment and Examples 1 to 6, the uniformity of the temperature distribution of the wafer 10 in the process using the electrostatic chuck can be improved, and the occurrence of localized heat spots can be suppressed.

[0063] In Examples 1 to 5, the ceramic substrate 110 includes an electrode 120 as a heater electrode. In this case, by making the pressure in the space defined by the wafer 10 and the annular protrusion 152 (back gas space) lower than the pressure of the process gas, an adsorption force due to differential pressure acts, and the wafer 10 can be adsorbed. By making the annular protrusion 152 into the shape described in the above embodiment and Examples 1 to 6, the uniformity of the temperature distribution of the wafer 10 in a process using a heater with a heating resistor can be improved, and the occurrence of localized heat spots can be suppressed.

[0064] In the above embodiments and examples 1 to 6, a cylindrical shaft 130 can be joined to the lower surface 113 of the ceramic substrate 110. This improves the thermal insulation of the substrate holding member 100 and improves the uniformity of the temperature distribution of the wafer 10.

[0065] <Change form> The embodiments described above are merely illustrative and can be modified as appropriate. For example, the shape and dimensions of the ceramic substrate 110 and the shaft 130 are not limited to those of the embodiments described above and can be modified as appropriate. Also, the height, width, and other dimensions, shape, and surface roughness Ra of the upper surface of the annular protrusion 152 can be modified as appropriate. Furthermore, the height of the multiple protrusions 156, the shape of the upper surface 156a, and the surface roughness Ra of the upper surface 156a can be modified as appropriate. In addition, the position, number, and shape (size of the central angle β, circumferential length, etc.) of the second portion 154 of the annular protrusion 152, and the surface roughness Ra of the upper surface 152a of the annular protrusion 152 can also be modified as appropriate. Furthermore, the ratio of the length of the first portion 153 to the length of the second portion 154 in the annular protrusion 152 can also be modified as appropriate, as long as the central angle β of the second portion 154 is 10° ≤ β.

[0066] Furthermore, the second portion 154 is not limited to being located radially inward of the first portion 153, but may also be located radially outward of the first portion 153. Also, the shape of the second portion 154 is not limited to the rectangular shape shown in Figures 1, 3, and 7, but can be changed as appropriate. For example, it can be shaped like the periodic portion 155 of the annular protrusion 152 shown in Figures 8 to 10.

[0067] For example, the shape of the upper surface 156a of the multiple protrusions 156 does not necessarily have to be circular, and can be any shape. In that case, however, it is preferable that it has an area equivalent to that of a circle with a diameter of 0.1 mm to 5 mm. Furthermore, in the above description, the multiple protrusions 156 were arranged in a concentric circle or distributed at the vertices of a square tiled without gaps, but the present invention is not limited to such embodiments. For example, the multiple protrusions 156 may be arranged to be distributed at random positions. Even in that case, it is preferable that the spacing between each of the multiple protrusions 156 is in the range of 1.5 mm to 30 mm.

[0068] In the above embodiment, the electrode 120 was made of molybdenum, tungsten, or an alloy containing molybdenum and / or tungsten, but the present invention is not limited to such embodiments. For example, metals or alloys other than molybdenum and tungsten can also be used. Furthermore, although the electrode 120 was a heater electrode as a heating element, the electrode 120 does not necessarily have to be a heater electrode as a heating element, and may be, for example, an electrostatic adsorption electrode or a high-frequency electrode.

[0069] In the above embodiment, the substrate holding member 100 was equipped with an electrode 120, but the present invention is not limited to such an embodiment, and the substrate holding member 100 does not necessarily have to be equipped with an electrode 120. Furthermore, even if the substrate holding member 100 is equipped with an electrode 120, the electrode 120 does not have to be embedded in the ceramic substrate 110 of the substrate holding member 100. For example, the electrode 120 may be attached to the back surface 113 of the ceramic substrate 110.

[0070] In the above embodiment, the substrate holding member 100 was equipped with a shaft 130, but the present invention is not limited to such an embodiment, and the substrate holding member 100 does not necessarily have to be equipped with a shaft 130. Furthermore, even if the substrate holding member 100 is equipped with a shaft 130, a second gas passage 168 extending in the vertical direction 5 is not required to be formed in the cylindrical portion 131 of the shaft 130. For example, instead of the second gas passage 168, a separate gas pipe can be provided in the hollow region of the cylindrical portion 131 (the region where the power supply line 140 is provided).

[0071] Although embodiments and modified versions of the invention have been described above, the technical scope of the present invention is not limited to the scope described above. It will be obvious to those skilled in the art that various modifications or improvements can be made to the above embodiments. It is also clear from the claims that such modified or improved forms may be included in the technical scope of the present invention.

[0072] The order in which each process in the manufacturing method shown in the specification and drawings is executed is not specifically defined, and unless the output of a previous process is used in a later process, the processes can be executed in any order. Even if phrases such as "first," and "next," are used for convenience, this does not mean that the processes must be performed in that order. [Explanation of symbols]

[0073] 100 Substrate holding member 110 Ceramic substrate 120 electrodes 130 shaft 140 Feed line 152 Annular protrusion 153 Part 1 154 Part 2 155 periodic part 156 Multiple protrusions

Claims

1. The ceramic substrate comprises an upper surface, a lower surface facing the upper surface in the vertical direction, and a side surface connecting the upper surface and the lower surface in the vertical direction. The aforementioned ceramic substrate is An annular protrusion is arranged on the outer periphery of the upper surface of the ceramic substrate and protrudes above the upper surface of the ceramic substrate, The ceramic substrate comprises a plurality of protrusions arranged inside the annular protrusion on the upper surface of the ceramic substrate and protruding upward from the upper surface of the ceramic substrate, The aforementioned annular protrusion is, A first part extending along the circumference, The first portion comprises a second portion extending radially outward or inward, The central angle β of the second part is １０°≦β And, A substrate holding member characterized in that the distance from the radial center of the ceramic substrate to the side surface is constant throughout the entire circumferential direction.

2. The substrate holding member according to claim 1, wherein the second portion extends radially inward from the first portion.

3. The ceramic substrate comprises an upper surface, a lower surface facing the upper surface in the vertical direction, and a side surface connecting the upper surface and the lower surface in the vertical direction. The aforementioned ceramic substrate is An annular protrusion is arranged on the outer periphery of the upper surface of the ceramic substrate and protrudes above the upper surface of the ceramic substrate, The ceramic substrate comprises a plurality of first protrusions arranged inside the annular protrusion on the upper surface of the ceramic substrate and projecting upward from the upper surface of the ceramic substrate, The annular protrusion has a plurality of periodic portions that extend in a direction different from the circumferential direction at predetermined intervals in the circumferential direction, A substrate holding member characterized in that the distance from the radial center of the ceramic substrate to the side surface is constant throughout the entire circumferential direction.

4. The substrate holding member according to claim 3, wherein of the plurality of first protrusions, the plurality of outermost protrusions located on the radially outermost side are arranged in the circumferential direction at predetermined intervals.

5. The substrate holding member according to claim 3 or 4, wherein the ceramic substrate further has a plurality of second protrusions arranged outside the annular protrusion on the upper surface of the ceramic substrate and protruding above the upper surface of the ceramic substrate.

6. The substrate holding member according to any one of claims 1 to 5, wherein the annular protrusion has a shape such that it crosses multiple imaginary lines extending radially from the center of the annular protrusion.

7. The substrate holding member according to any one of claims 1 to 6, wherein the ceramic substrate includes an electrode for electrostatic adsorption.

8. The substrate holding member according to any one of claims 1 to 7, wherein the ceramic substrate includes a heat-generating resistor.

9. Furthermore, the substrate holding member according to any one of claims 1 to 8, further comprising a cylindrical shaft joined to the lower surface of the ceramic substrate.

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