Holding member and electrostatic chuck

Abstract

To provide a holding member in which a porous body maintaining a good structure is arranged in a plate-like member.SOLUTION: A holding member for holding an object includes a plate-shaped member having a holding surface for holding the object and having a through-hole formed therein, and a porous body press-fitted and fixed in the through-hole and allowing a gas to flow therethrough, wherein a main component of a material forming the plate-shaped member and a main component of a material forming the porous body are ceramics.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a holding member and an electrostatic chuck. [Background technology]

[0002] Electrostatic chucks that use electrostatic attraction to hold a wafer as a holding member for an object are known. For example, Patent Document 1 discloses an electrostatic chuck that includes a ceramic plate having a wafer mounting surface and a through-hole formed therein, and a porous resin body press-fitted into the through-hole. The porous body allows helium gas to pass through, improving thermal conductivity between the wafer and the ceramic plate, while suppressing arc discharge caused by collisions between electrons ionized from helium and other helium gases. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-101194 Summary of the Invention [Problem to be solved by the invention]

[0004] In the electrostatic chuck disclosed in Patent Document 1, when a resin porous body is press-fitted into a through-hole, wear may occur on the surface of the porous body that contacts the through-hole. If the structure of the porous body is damaged by such wear, the amount of gas that can flow through the porous body may decrease, and the efficiency of thermal conduction between the wafer and the ceramic plate may decrease. For this reason, there has been a demand for the development of a holding member that includes a porous body press-fitted and fixed into a through-hole while maintaining a good structure.

[0005] The present invention has been made to solve at least some of the above-mentioned problems, and aims to provide a holding member in which a porous body is arranged within a plate-shaped member while maintaining a good structure. [Means for solving the problem]

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following forms.

[0007] (1) According to one aspect of the present invention, there is provided a holding member comprising: a plate-shaped member having a holding surface for holding an object and having a through hole formed therein; and a porous body press-fitted and fixed into the through hole, through which gas can flow, wherein the main component of the material forming the plate-shaped member and the main component of the material forming the porous body are ceramics.

[0008] According to this configuration, the main component of the material forming the holding member and the main component of the material forming the porous body are ceramics. Generally, ceramics have excellent abrasion resistance, and therefore, according to this configuration, the surface of the porous body press-fitted and fixed into the through-hole is prevented from experiencing abrasion during press-fitting into the through-hole. Therefore, the structure of the porous body is not significantly damaged by abrasion during press-fitting into the through-hole. Therefore, according to this configuration, a holding member can be provided in which the porous body is disposed within a plate-like member while maintaining a good structure.

[0009] (2) In the holding member of the above aspect, the value obtained by dividing the amount of deformation of the porous body when the load is applied by an indenter by the amount of deformation of the porous body when the load is removed may be greater than 0.5. According to this configuration, the porous body, which undergoes a relatively large amount of deformation under load, is press-fitted and fixed into the through-hole. In other words, the porous body is prone to plastic deformation and is less likely to break when pressed into the through-hole. Therefore, according to this configuration, it is possible to provide a holding member in which the porous body, which maintains a good structure, is disposed within the plate-like member.

[0010] (3) In the retaining member of the above aspect, when a region of the porous body that is farther than a predetermined distance from the central axis is defined as a peripheral region and a region from the central axis to the predetermined distance is defined as a central region, the porosity in the central region may be higher than the porosity in the peripheral region. With this configuration, the porosity is higher in the central region than in the peripheral region. In other words, the gas flows more easily in the central region, where the gas flow rate tends to be higher than in the peripheral region, and this ensures a sufficient flow rate of gas flowing through the porous body. As a result, sufficient gas can be supplied to the holding surface.

[0011] (4) In the holding member of the above aspect, the porous body may have a Young's modulus of 1 GPa or more and less than 100 GPa. According to this configuration, the porous body having a relatively low Young's modulus is press-fitted and fixed into the through-hole. That is, the porous body is easily deformed and is unlikely to break when pressed into the through-hole. Therefore, according to this configuration, it is possible to provide a holding member in which the porous body is disposed within the plate-like member while maintaining a good structure.

[0012] (5) In the holding member of the above aspect, the main component of the material forming the plate-like member may be the same as the main component of the material forming the porous body. According to this configuration, the main component of the material forming the plate-like member and the main component of the material forming the porous body are the same ceramic, and therefore the main components of the materials forming both have the same thermal expansion coefficient, which reduces the possibility of damage caused by the difference in thermal expansion coefficients even when the holding member is repeatedly heated and cooled.

[0013] (6) In the holding member of the above aspect, the Poisson's ratio of the porous body may be 0.0011 or less. According to this configuration, a holding member can be provided in which the porous body is well held in the plate-shaped member, and cracks in the plate-shaped member do not occur due to the porous body being press-fitted and fixed into the through hole.

[0014] (7) According to another aspect of the present invention, there is provided an electrostatic chuck, comprising: a holding member according to any one of (1) to (6) above; and an electrostatic electrode that generates an electrostatic attractive force on the holding surface. According to this configuration, when power is supplied to the electrostatic electrode, an electrostatic attraction (adsorption force) is generated, and the object can be held on the holding surface side by this electrostatic attraction force. In addition, since the material forming the porous body press-fitted and fixed in the through hole is mainly composed of ceramics, it is possible to provide an electrostatic chuck in which the porous body is disposed within the plate-shaped member while maintaining a good structure.

[0015] The present invention can be realized in various forms, for example, a holding member, an electrostatic chuck including an electrostatic electrode that generates electrostatic attraction between the holding member and the holding surface of the holding member, a vacuum chuck, a ceramic heater, a semiconductor manufacturing apparatus, a component including any of these, and a manufacturing method for these. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is an explanatory diagram schematically illustrating a cross-sectional configuration of an electrostatic chuck according to an embodiment of the present invention. [Figure 2] FIG. 2 is an explanatory diagram showing a porous body as viewed from the +Z axis direction side. [Figure 3] FIG. 10 is an explanatory diagram showing a load-displacement curve. [Figure 4] FIG. 1 is an explanatory diagram showing Young's modulus of porous bodies having different porosities. [Figure 5] FIG. 1 is an explanatory diagram showing the results of an evaluation test performed on an example and a comparative example. [Figure 6] FIG. 10 is an explanatory diagram showing the relationship between the holding force and the Poisson's ratio. DETAILED DESCRIPTION OF THE INVENTION

[0017] FIG. 1 is an explanatory diagram schematically illustrating a cross-sectional configuration of an electrostatic chuck 1 according to an embodiment of the present invention. The electrostatic chuck 1 is a device that attracts and holds a semiconductor wafer W, which is an object, by electrostatic attraction. In FIG. 1, mutually orthogonal X, Y, and Z axes are shown to identify directions. The arrow in FIG. 1 indicates the direction (-Z axis direction) in which the semiconductor wafer W is held relative to the electrostatic chuck 1. The electrostatic chuck 1 is used, for example, to fix the semiconductor wafer W in a vacuum chamber of a semiconductor manufacturing device. The electrostatic chuck 1 includes a plate-like member 10, a base member 20, an adhesive member 30, an electrostatic electrode 40, and a heater electrode 50.

[0018] The plate-shaped member 10 is a disk-shaped member. The main component of the material forming the plate-shaped member 10 is ceramic. The main component refers to the component with the highest volume content. Examples of materials forming the plate-shaped member 10 include aluminum oxide (alumina, Al2O3) and aluminum nitride (AlN), and in this embodiment, aluminum oxide or aluminum nitride is used. The plate-shaped member 10 has a holding surface 10f. The holding surface 10f is a circular surface facing the side that holds the semiconductor wafer W (the side in the +Z-axis direction). Although not shown in FIG. 1, a seal band is formed along the outer edge of the holding surface 10f, and small circular protrusions are formed scattered inside the seal band.

[0019] The base member 20 is a disk-shaped member having a larger diameter than the plate-shaped member 10. Materials forming the base member 20 include metals and various composite materials. Examples of metals forming the base member 20 include Al (aluminum), Ti (titanium), and alloys thereof. Examples of composite materials forming the base member 20 include a composite material formed by melting an aluminum alloy, the main component of which is aluminum, into porous ceramics, the main component of which is silicon carbide (SiC), and pressurizing and infiltrating the porous ceramics. The aluminum alloy contained in the composite material may contain Si (silicon) or Mg (magnesium), or may contain other elements as long as they do not affect the properties, etc.

[0020] A coolant flow path 21 is formed inside the base member 20. When a coolant (for example, a fluorine-based inert liquid or water) flows through the coolant flow path 21, the base member 20 is cooled. At this time, the plate-like member 10 is also cooled by heat transfer (heat dissipation) between the base member 20 and the plate-like member 10 via the adhesive member 30 described below, and the semiconductor wafer W held on the holding surface 10f of the plate-like member 10 is also cooled.

[0021] The adhesive member 30 is disposed between the plate-shaped member 10 and the base member 20, and bonds the plate-shaped member 10 to the base member 20. The adhesive member 30 is made of an adhesive material such as a silicone resin, an acrylic resin, or an epoxy resin.

[0022] The electrostatic electrode 40 is a disk-shaped member provided inside the plate-shaped member 10 and is made of a conductive material such as tungsten or molybdenum. When power is supplied from an external power source (not shown), the electrostatic electrode 40 generates an electrostatic attractive force on the holding surface 10f. The semiconductor wafer W is held on the holding surface 10f (specifically, on the upper surface of the seal band and the upper surfaces of the small circular protrusions) by this electrostatic attractive force.

[0023] The heater electrode 50 is provided inside the plate-shaped member 10 and is made of a conductive material such as tungsten or molybdenum. The heater electrode 50 generates heat when power is supplied from an external power source (not shown). This heat warms the plate-shaped member 10, and the semiconductor wafer W attracted to the holding surface 10f of the plate-shaped member 10 is also warmed.

[0024] The electrostatic chuck 1 has a through-hole HL formed therein along the Z-axis direction. An inert gas such as He supplied from the −Z-axis direction side of the base member 20 is sent to the holding surface 10f through the through-hole HL. When the semiconductor wafer W is held on the holding surface 10f, the inert gas sent to the holding surface 10f through the through-hole HL remains between the semiconductor wafer W and the holding surface 10f, improving thermal conduction between the semiconductor wafer W and the plate-like member 10.

[0025] The through hole HL is composed of a first through hole 12, a second through hole 22, and a third through hole 32. The third through hole 32 is a through hole formed along the Z-axis direction inside the base member 20. The second through hole 22 is a through hole formed along the Z-axis direction inside the adhesive member 30, and is connected to an end of the third through hole 32 on the +Z-axis direction side. The first through hole 12 is a through hole formed along the Z-axis direction inside the plate-shaped member 10, and is connected to an end of the second through hole 22 on the +Z-axis direction side.

[0026] A press-fit space 12s is provided at the end of the first through-hole 12 on the +Z-axis direction side, and serves as a space for press-fitting and fixing a porous body 60 (described later). In the first through-hole 12, the cross section of the press-fit space 12s (a cross section cut along the XY plane) is wider than the cross section of the portion on the −Z-axis direction side of the press-fit space 12s. The press-fit space 12s is exposed on the holding surface 10f side of the plate-shaped member 10. The porous body 60 is press-fitted and fixed in the first through-hole 12 (the press-fit space 12s) and is a member through which gas can flow. Specifically, a large number of pores are formed inside the porous body 60, and these pores are interconnected, allowing gas to flow through the inside of the porous body 60. The plate-shaped member 10 and the porous body 60 of the electrostatic chuck 1 correspond to a holding member H that holds a semiconductor wafer W as an object.

[0027] In this embodiment, the shape of the press-fit space 12s and the shape of the porous body 60 are both cylindrical. The main component of the material forming the porous body 60 is ceramic. Examples of materials forming the porous body 60 include aluminum oxide (alumina, Al2O3), aluminum nitride (AlN), and yttrium oxide (yttria, Y2O3), and in this embodiment, aluminum oxide (alumina) is used. That is, in this embodiment, the main component of the material forming the plate-shaped member 10 and the main component of the material forming the porous body 60 are ceramics, but the former is aluminum nitride and the latter is alumina. Alternatively, the former may be alumina and the latter may be yttria. Therefore, in this embodiment, the main component of the material forming the plate-shaped member 10 is different from the main component of the material forming the porous body 60.

[0028] FIG. 2 is an explanatory diagram showing the porous body 60 as viewed from the +Z-axis direction. In FIG. 2, the central axis O is the central axis of the cylindrical porous body 60 extending along the Z-axis direction. As shown in FIG. 2, the region of the porous body 60 that is farther away from the central axis O than a predetermined distance V is defined as the peripheral region SA, and the region from the central axis O to the set distance V is defined as the central region CA. The porosity in the central region CA is higher than the porosity in the peripheral region SA. The porosity in each region of the porous body 60 may be adjusted by adjusting the particle size and amount of the pore-forming agent contained in each region of the porous body 60 before firing. The porosity in the central region CA and the porosity in the peripheral region SA are each calculated by dividing the porous body 60 extracted from the plate-like member 10 into the central region CA and the peripheral region SA, and then calculating the ratio of voids (pores) to the solid portion of the porous body 60 for each region through image analysis.

[0029] FIG. 3 is an explanatory diagram showing a load-displacement curve obtained by performing nanoindentation on the surface of porous body 60 before it was press-fitted and fixed to plate-like member 10. Nanoindentation was performed using a nanoindenter device (FISCHERSCOPE HM2000, manufactured by FISCHER TECHNOLOGY INC). The conditions used during the experiment were a Vickers indenter, a loading / unloading rate of 2 mN / sec, and 1000 sec. 1000 sec is the time required for a load of 2 N to be applied at a loading rate of 2 mN / sec. The horizontal axis of FIG. 3 represents displacement, and the vertical axis of FIG. 3 represents load.

[0030] In FIG. 3 , the maximum displacement hmax is the amount of deformation of the porous body 60 when the load applied by the indenter reaches its maximum. The post-unload displacement hp is the amount of deformation of the porous body 60 when the load applied by the indenter is released, and can also be considered the amount of plastic deformation that does not return to its original state even when the load is released. The porous body 60 included in the electrostatic chuck 1 of this embodiment is relatively susceptible to plastic deformation. That is, the value obtained by dividing the amount of deformation of the porous body 60 when the load is applied by the indenter (maximum displacement hmax) by the amount of deformation of the porous body 60 when the load is released (post-unload displacement hp) is greater than 0.5. Note that the properties of the porous body 60 do not change significantly even when the porous body 60 is press-fitted and fixed to the plate-like member 10. Therefore, when nanoindentation is performed using a similar nanoindenter device, even when the porous body 60 is press-fitted and fixed to the plate-like member 10, the value obtained by dividing the post-unload displacement hp by the maximum displacement hmax is greater than 0.5. Of course, even if the porous body 60 press-fitted and fixed to the plate-like member 10 is pulled out of the plate-like member 10 and nanoindentation is performed, the value obtained by dividing the post-unloading displacement hp by the maximum displacement hmax will be greater than 0.5.

[0031] FIG. 4 is an explanatory diagram showing the Young's modulus of porous bodies 60 with different porosities. The horizontal axis of FIG. 4 represents relative density (100-porosity), and the vertical axis of FIG. 4 represents Young's modulus. The Young's modulus values ​​shown in FIG. 4 were calculated using load-displacement curves obtained by performing nanoindentation on each of the porous bodies 60 with different porosities (relative densities). Note that the porosity of the porous body 60 here refers to the porosity of the entire porous body 60, without distinguishing between the central region CA and the peripheral region SA. The Young's modulus of the porous body 60 included in the electrostatic chuck 1 of this embodiment is relatively low. That is, the Young's modulus of the porous body 60 is 1 GPa or more and less than 100 GPa. Referring to FIG. 4, the electrostatic chuck 1 of this embodiment includes a porous body 60 with a porosity ranging from 57.2 to 80.0%. The Young's modulus of such porous body 60 does not change significantly either before or after it is press-fitted and fixed to plate-like member 10, and therefore, when the Young's modulus of porous body 60 is measured in either state, the value is 1 GPa or more and less than 100 GPa. Of course, even when the porous body 60 that has been press-fitted and fixed to plate-like member 10 is pulled out of the plate-like member 10 and the Young's modulus is measured, the Young's modulus of porous body 60 will be 1 GPa or more and less than 100 GPa. The Young's modulus of porous body 60 is measured using the device (FISCHERSCOPE HM2000, manufactured by FISCHER TECHNOLOGY INC) described in FIG. 3.

[0032] FIG. 5 is an explanatory diagram showing a table of the results of evaluation tests conducted on cylindrical porous bodies in Examples 1 to 13 and Comparative Examples 1 to 4. In the table of FIG. 5, "porous body material" indicates the material forming each of Examples 1 to 13 and Comparative Examples 1 to 4. In the table of FIG. 5, "porous body diameter" indicates the diameter of each of Examples 1 to 13 and Comparative Examples 1 to 4, measured in cm. In the table of FIG. 5, "Poisson's ratio" indicates the Poisson's ratio of each of Examples 1 to 13 and Comparative Examples 1 to 4. The Poisson's ratio of each of Examples 1 to 13 and Comparative Examples 1 to 4 is calculated using the following method. First, an operator prepares a cylindrical PVC container (with a Young's modulus of approximately 2 to 5 GPa) with a diameter of 40 mm and a length of 80 mm, equipped with a strain gauge, and a porous body (each of Examples 1 to 13 and Comparative Examples 1 to 4) with a diameter of 40 mm and a length of 40 mm. Next, the operator places the porous body to be measured near the center of the PVC container, presses the porous body from above and below until it breaks, and measures the axial and radial strains.The operator then uses the measured axial and radial strains to calculate the Poisson's ratio of the porous body to be measured.

[0033] "Substrate material" in the table of Fig. 5 indicates the material forming the substrate into which each of Examples 1 to 13 and Comparative Examples 1 to 4 is press-fit. Note that ALN in "substrate material" stands for aluminum nitride. "Hole diameter" in the table of Fig. 5 indicates the diameter of the hole on the substrate into which each of Examples 1 to 13 and Comparative Examples 1 to 4 is press-fit, and is expressed in cm.

[0034] In Example 3 (7), Examples 9 to 11, and Comparative Examples 1 to 4, the "porous body material" is aluminum and the "porous body diameter" is 4.02, but the "Poisson's ratio" is different. This is due to the difference in pore distribution caused by the difference in the treatment for making the porous body when producing each Example and Comparative Example.

[0035] The "holding force" in the table of FIG. 5 indicates the holding force exerted by the substrate when each of Examples 1 to 13 and Comparative Examples 1 to 4 was pressed into the substrate. The "holding force" was evaluated as "Good" if it was 15 N or more, "Poor" if it was less than 15 N, and "-" if the substrate was broken and could not be evaluated. The "substrate crack" in the table of FIG. 5 indicates whether or not cracks occurred in the substrate when each of Examples 1 to 13 and Comparative Examples 1 to 4 was pressed into the substrate. The "substrate crack" was evaluated as "Poor" if cracks occurred in the substrate, and "-" if no cracks occurred in the substrate.

[0036] As shown in the table of FIG. 5 , the "holding force" was "good" for all of Examples 1 to 13, and the "substrate cracking" was "-". On the other hand, the "substrate cracking" for Comparative Examples 1 and 2 was "-", but the "holding force" for Comparative Examples 1 and 2 was "x". Furthermore, the "holding force" for Comparative Examples 3 and 4 was "-", and the "substrate cracking" for Comparative Examples 3 and 4 was "x". These results are thought to be due to the "Poisson's ratio". Therefore, since the Poisson's ratios of Examples 1 to 13, which were superior to those of Comparative Examples 1 to 4 in terms of "holding force" and "substrate cracking", were 0.0011 or less, the electrostatic chuck 1 of this embodiment also employs a porous body 60 having a Poisson's ratio of 0.0011 or less.

[0037] Fig. 6 is an explanatory diagram showing the relationship between holding force and Poisson's ratio. Plots P12 and P13 in Fig. 6 correspond to Examples 12 and 13 described in Fig. 5, and plot PC1 in Fig. 6 corresponds to Comparative Example 1 described in Fig. 5. The holding forces exerted by the substrate when Examples 12 and 13 were press-fitted into the substrate were 87.6 N and 50 N, respectively. The dashed line DL in Fig. 6 indicates that the holding force increases as the Poisson's ratio decreases.

[0038] In the electrostatic chuck 1 according to the embodiment described above, the main component of the material forming the plate-shaped member 10 and the main component of the material forming the porous body 60 are ceramics. Generally, ceramics have excellent abrasion resistance. Therefore, in the electrostatic chuck 1 described above, the surface of the porous body 60 press-fitted and fixed in the first through-hole 12 (press-fit space 12s) is prevented from abrasion during press-fitting into the first through-hole 12. Therefore, the structure of the porous body 60 is not significantly damaged by abrasion during press-fitting into the first through-hole 12. Therefore, the electrostatic chuck 1 described above is an electrostatic chuck 1 in which the porous body 60 is disposed within the plate-shaped member 10 while maintaining its excellent structure. As a result, when the semiconductor wafer W is held on the holding surface 10f, an inert gas can be smoothly supplied between the semiconductor wafer W and the plate-shaped member 10.

[0039] Furthermore, the porous body 60 included in the above-described electrostatic chuck 1 has a property such that, before being press-fitted and fixed to the plate-like member 10, the value obtained by dividing the amount of deformation of the porous body 60 in a state where the load is applied by the indenter (maximum displacement hmax) by the amount of deformation of the porous body 60 in a state where the load is removed (post-unloading displacement hp) is greater than 0.5. Therefore, it can be said that the porous body 60, which has a relatively large amount of deformation due to the load, is press-fitted and fixed to the first through-hole 12 (press-fitting space 12s). In other words, the porous body 60 is easily plastically deformed and is unlikely to break when press-fitted into the first through-hole 12. Therefore, the above-described electrostatic chuck 1 is an electrostatic chuck 1 in which the porous body 60, which maintains a good structure, is disposed in the plate-like member 10.

[0040] Furthermore, the porosity of the central region CA of the porous body 60 included in the electrostatic chuck 1 described above is higher than the porosity of the peripheral region SA. Therefore, the gas flows more easily in the central region CA, where the gas flow rate tends to be higher than in the peripheral region SA, and therefore a sufficient flow rate of the gas flowing through the porous body 60 can be ensured. As a result, a sufficient gas supply to the holding surface 10f is possible.

[0041] Furthermore, the Young's modulus of the porous body 60 included in the above-described electrostatic chuck 1 is equal to or greater than 1 GPa and less than 100 GPa before being press-fitted and fixed into the plate-like member 10. Therefore, it can be said that the porous body 60, which has a relatively low Young's modulus, is press-fitted and fixed into the first through-hole 12 (press-fitting space 12s). In other words, the porous body 60 is easily deformed and is unlikely to break when press-fitted into the first through-hole 12. Therefore, the above-described electrostatic chuck 1 is an electrostatic chuck 1 in which the porous body 60, while maintaining a good structure, is disposed in the plate-like member 10.

[0042] The Poisson's ratio of the porous body 60 included in the electrostatic chuck 1 described above is equal to or less than 0.0011. Therefore, it is possible to provide a holding member 1 in which the porous body 60 is well held on the plate-shaped member 10 and cracks in the plate-shaped member 10 due to the porous body 60 press-fitted and fixed in the through-hole HL are not generated.

[0043] In the electrostatic chuck 1 of this embodiment, when power is supplied to the electrostatic electrode 40, an electrostatic attractive force (adsorption force) is generated, and the semiconductor wafer W can be held on the holding surface 10f side by this electrostatic attractive force. In addition, since the porous body 60 press-fitted and fixed in the first through-hole 12 (press-fit space 12s) is mainly made of ceramics, the electrostatic chuck 1 of this embodiment is an electrostatic chuck 1 in which the porous body 60 is disposed within the plate-like member 10 while maintaining a good structure.

[0044] <Modification of this embodiment> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0045] In the above embodiment, the press-fit space 12s is provided at the end of the first through hole 12 on the +Z axis direction side, but the present invention is not limited to this. For example, a press-fit space having a cross section (a cross section cut along the XY plane) large enough to press-fit and fix the porous body 60 may be provided not only at the end of the first through hole 12 on the +Z axis direction side, but also extending from that end to the -Z axis direction side. Furthermore, such a press-fit space may be provided from the end of the first through hole 12 on the +Z axis direction side to the end of the -Z axis direction side, or may further extend to the second through hole 22.

[0046] In the above embodiment, the shapes of the press-fit space 12s and the porous body 60 are both cylindrical, but this is not limiting. As long as the shapes of the press-fit space 12s and the porous body 60 are substantially the same, they may be rectangular columns or any three-dimensional shape.

[0047] In the above embodiment, the main component of the material forming the plate-shaped member 10 is different from the main component of the material forming the porous body 60, but this is not limited to this. The main component of the material forming the plate-shaped member 10 may be the same as the main component of the material forming the porous body 60. Specifically, for example, the main component of the material forming the plate-shaped member 10 and the main component of the material forming the porous body 60 may both be alumina or aluminum nitride. That is, in such a case, the main component of the material forming the plate-shaped member 10 and the main component of the material forming the porous body 60 are the same ceramic. Therefore, the main components of the materials forming both have the same thermal expansion coefficient, and therefore, even if the holding members (plate-shaped member 10 and porous body 60) are repeatedly heated and cooled, the possibility of damage caused by the difference in thermal expansion coefficient can be reduced.

[0048] In the above embodiment, the through hole HL is formed along the Z-axis direction inside the electrostatic chuck 1, but is not limited thereto. As long as the press-fitting space 12s into which the porous body 60 is press-fitted and fixed is provided at the end of the through hole HL on the +Z-axis direction side, the through hole HL may be formed to include a portion along the Z-axis direction as well as a portion along the X-axis direction, the Y-axis direction, or any other arbitrary direction, a curved portion, or any other shape.

[0049] This aspect has been described above based on embodiments and modifications. However, the above-described embodiments are intended to facilitate understanding of this aspect and are not intended to limit this aspect. This aspect may be modified or improved without departing from the spirit and scope of the claims, and equivalents thereof are included in this aspect. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0050] The present invention can also be realized in the following forms. [Application example 1] A holding member for holding an object, a plate-like member having a holding surface for holding the object and having a through hole formed therein; a porous body that is press-fitted and fixed into the through hole and through which gas can flow, A holding member, characterized in that the main component of the material forming said plate-like member and the main component of the material forming said porous body are ceramics. [Application example 2] The holding member according to Application Example 1, A holding member, characterized in that the value obtained by dividing the amount of deformation of the porous body when the load is applied by an indenter by the amount of deformation of the porous body when the load is removed is greater than 0.5. [Application example 3] The holding member according to Application Example 1 or Application Example 2, A retaining member characterized in that, when a region of the porous body farther than a predetermined distance from a central axis is defined as a peripheral region, and a region from the central axis to the predetermined distance is defined as a central region, the porosity of the central region is higher than the porosity of the peripheral region. [Application example 4] The holding member according to any one of Application Examples 1 to 3, A holding member characterized in that the porous body has a Young's modulus of 1 GPa or more and less than 100 GPa. [Application example 5] The holding member according to any one of Application Examples 1 to 4, A holding member, characterized in that the main component of the material forming said plate-like member is the same as the main component of the material forming said porous body. [Application Example 6] The holding member according to any one of Application Examples 1 to 5, A holding member characterized in that the Poisson's ratio of the porous body is 0.0011 or less. [Application Example 7] An electrostatic chuck, A holding member according to any one of Application Examples 1 to 6; an electrostatic electrode that generates an electrostatic attractive force on the holding surface. [Explanation of symbols]

[0051] 1...Electrostatic chuck 10...Plate-shaped member 10f…Holding surface 12...First through hole 12s...Press-fit space 20...Base member 21... Refrigerant flow path 22...Second through hole 30...Adhesive material 32...Third through hole 40...Electrostatic electrode 50...Heater electrode 60...Porous material CA…Central area H...Holding member HL...Through hole O…Central axis SA: Peripheral area V: Set distance

Claims

1. A holding member for holding an object, a plate-like member having a holding surface for holding the object and having a through hole formed therein; a porous body that is press-fitted and fixed into the through hole and through which gas can flow, A holding member, characterized in that the main component of the material forming said plate-like member and the main component of the material forming said porous body are ceramics.

2. The holding member according to claim 1, A holding member, characterized in that the value obtained by dividing the amount of deformation of the porous body when the load is removed by the amount of deformation of the porous body when the load is applied by an indenter is greater than 0.

5.

3. The holding member according to claim 1, A retaining member characterized in that, when a region of the porous body farther than a predetermined distance from a central axis is defined as a peripheral region, and a region from the central axis to the predetermined distance is defined as a central region, the porosity of the central region is higher than the porosity of the peripheral region.

4. The holding member according to claim 1, A holding member characterized in that the porous body has a Young's modulus of 1 GPa or more and less than 100 GPa.

5. The holding member according to claim 1, A holding member, characterized in that the main component of the material forming said plate-like member is the same as the main component of the material forming said porous body.

6. The holding member according to claim 1, A holding member characterized in that the Poisson's ratio of the porous body is 0.0011 or less.

7. An electrostatic chuck, A holding member according to any one of claims 1 to 6; an electrostatic electrode that generates an electrostatic attractive force on the holding surface.

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