Electrostatic attraction member and substrate fixing device

Abstract

To provide an electrostatic adsorption member and a substrate fixing device that further suppress abnormal discharge.SOLUTION: An electrostatic adsorption member 30 includes a dielectric member 41 having a first surface 41A and a second surface 41B opposite to the first surface, and having a through hole 120 penetrating from the first surface to the second surface, and a porous body 110 provided in the through hole and having a third surface 113 flush with the first surface. The through hole includes a first opening 121 separated from the first surface by a first distance in a first direction perpendicular to the first surface, and a second opening spaced from the first surface in the first direction by a second distance that is greater than the first distance. At least a part of the first opening is inside the second opening 122 when viewed in plan from the first direction. The porous body includes a first portion 131 located inside the first opening in plan view from the first direction, and a second portion 132 connected to the first portion and positioned outside the first opening.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an electrostatic attraction member and a substrate fixing device. [Background technology]

[0002] A known substrate fixing device used for fixing a substrate such as a wafer has an electrostatic attraction member having a through hole for cooling gas to cool the substrate, and a porous body provided within the through hole to suppress abnormal discharge. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-209615 A [Patent Document 2] JP 2013-232641 A [Patent Document 3] JP 2017-218352 A Summary of the Invention [Problem to be solved by the invention]

[0004] Even with a conventional substrate fixing device provided with a porous body, abnormal discharge may occur.

[0005] An object of the present disclosure is to provide an electrostatic attraction member and a substrate fixing device that can further suppress abnormal discharge. [Means for solving the problem]

[0006] According to one embodiment of the present disclosure, there is provided a dielectric member having a first surface and a second surface opposite to the first surface, the dielectric member having a through hole formed therein penetrating from the first surface to the second surface, and a porous body provided within the through hole and having a third surface flush with the first surface, the through hole having a first opening separated from the first surface by a first distance in a first direction perpendicular to the first surface, and a second opening separated from the first surface by a second distance in the first direction that is greater than the first distance, at least a part of the first opening is inside the second opening in a plan view from the first direction, and the porous body has a first portion located inside the first opening and a second portion connected to the first portion and located outside the first opening in a plan view from the first direction. The first opening is entirely inside the second opening in a plan view from the first direction. An electrostatic attraction member is provided. Effect of the Invention

[0007] According to the present disclosure, abnormal discharge can be further suppressed. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing a substrate fixing device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing an electrostatic attraction member in the first embodiment. [Diagram 3] FIG. 11 is a cross-sectional view showing an electrostatic attraction member in a second embodiment. [Figure 4] FIG. 11 is a cross-sectional view showing an electrostatic attraction member in a third embodiment. [Diagram 5] FIG. 13 is a cross-sectional view showing an electrostatic attraction member in a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present inventors have conducted intensive research to determine the cause of abnormal discharge even in a conventional substrate fixing device provided with a porous body. As a result, it has become clear that the porous body may detach from the through hole when the substrate is not placed on the electrostatic adsorption member, such as during maintenance of the substrate fixing device. For example, when the porous body is bonded to the inner wall surface of the through hole with an adhesive, the adhesive may deteriorate due to repeated irradiation of plasma for substrate processing. When the adhesive is deteriorated and a cooling gas is supplied to the through hole from a gas path provided in the base plate, the porous body may detach from the through hole due to the gas pressure. Even when the porous body is embedded in the through hole using an inorganic paste, the adhesion strength decreases due to deterioration over time, and when a cooling gas is supplied to the through hole from a gas path provided in the base plate, the porous body may detach from the through hole due to the gas pressure. When the porous body detaches, abnormal discharge is more likely to occur during subsequent substrate processing.

[0010] The present disclosure has been made based on such findings, and suppresses detachment from the through-holes of a porous body, thereby further suppressing abnormal discharge.

[0011] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are denoted by the same reference numerals, and redundant description may be omitted.

[0012] (First embodiment) First, a description will be given of the first embodiment. Fig. 1 is a cross-sectional view showing a substrate fixing device according to the first embodiment.

[0013] As shown in FIG. 1, the substrate fixing device 1 according to the first embodiment has a base plate 10, an adhesive layer 20, and an electrostatic adsorption member 30 as main components.

[0014] The base plate 10 is a member for mounting the electrostatic attraction member 30. The thickness of the base plate 10 can be, for example, about 20 mm to 50 mm. The base plate 10 is made of, for example, aluminum, and can also be used as an electrode for controlling plasma. By supplying a predetermined high-frequency power to the base plate 10, it is possible to control the energy for causing the generated ions in a plasma state to collide with a substrate such as a wafer attracted to the electrostatic attraction member 30, thereby enabling an effective etching process.

[0015] A water channel 15 is provided inside the base plate 10. The water channel 15 has a cooling water inlet 15A at one end and a cooling water outlet 15B at the other end. The water channel 15 is connected to a cooling water control device (not shown) provided outside the substrate fixing device 1. The cooling water control device (not shown) introduces cooling water from the cooling water inlet 15A into the water channel 15 and discharges the cooling water from the cooling water outlet 15B. By circulating the cooling water through the water channel 15 to cool the base plate 10, the substrate attracted to the electrostatic attraction member 30 can be cooled.

[0016] A gas path 16 is further provided inside the base plate 10. An inert gas such as helium (He) gas for cooling the substrate attracted to the electrostatic attraction member 30 is introduced into the gas path 16.

[0017] The electrostatic attraction member 30 has a base 31, an electrostatic electrode 32, and a heating element 33. The electrostatic attraction member 30 is, for example, a Johnsen-Rahbek type electrostatic chuck. The electrostatic attraction member 30 may also be a Coulomb force type electrostatic chuck.

[0018] The substrate 31 includes a dielectric member 41 and a plurality of porous bodies 110 .

[0019] The material of the dielectric member 41 is, for example, ceramics such as aluminum oxide (Al2O3), aluminum nitride (AlN), etc. The thickness of the dielectric member 41 is, for example, about 1 mm to 10 mm, and the relative dielectric constant of the dielectric member 41 is, for example, about 9 to 10 at a frequency of 1 kHz.

[0020] The dielectric member 41 has a first surface 41A and a second surface 41B opposite to the first surface 41A. The second surface 41B is adhered to the base plate 10 by an adhesive layer 20. A substrate is adsorbed to the first surface 41A. The dielectric member 41 is formed with a plurality of through holes 120 penetrating from the first surface 41A to the second surface 41B. The through holes 120 communicate with the gas passage 16 of the base plate 10. A porous body 110 is provided in each of the through holes 120. The shapes of the porous bodies 110 and the through holes 120 will be described later.

[0021] The electrostatic electrode 32 is, for example, a thin-film electrode, and is built into the dielectric member 41. The electrostatic electrode 32 is connected to a power source provided outside the substrate fixing device 1, and when a predetermined voltage is applied, an electrostatic adsorption force is generated between the electrostatic electrode 32 and the substrate, and the substrate can be adsorbed and held on the electrostatic adsorption member 30. The adsorption and holding force becomes stronger as the voltage applied to the electrostatic electrode 32 becomes higher. The electrostatic electrode 32 may be of a monopolar or bipolar shape. For example, a sintered body of tungsten or molybdenum can be used as the electrostatic electrode 32.

[0022] The heating element 33 is built in the dielectric member 41. For example, a sintered body of tungsten or molybdenum can be used as the heating element 33. A rolled alloy may also be used as the heating element 33.

[0023] The adhesive layer 20 adheres the electrostatic attraction member 30 to the base plate 10. For example, a silicone adhesive can be used as the adhesive layer 20. The adhesive layer 20 may contain a filler such as alumina or aluminum nitride. The thickness of the adhesive layer 20 is, for example, about 0.1 mm to 3 mm. The adhesive layer 20 preferably has a thermal conductivity of 2 W / (m·K) or more. The adhesive layer 20 may be formed of one layer or multiple layers. For example, by using a two-layer structure in which an adhesive with high thermal conductivity and an adhesive with low elasticity are combined, it is possible to reduce the stress caused by the difference in thermal expansion between the base plate 10 and the electrostatic attraction member 30.

[0024] Here, the shapes of the porous body 110 and the through-holes 120 will be described. Fig. 2 is a diagram showing the electrostatic adsorption member 30 in the first embodiment. Fig. 2(a) is a plan view, and Fig. 2(b) is a cross-sectional view. Fig. 2(b) corresponds to a cross-sectional view taken along line IIb-IIb in Fig. 2(a).

[0025] As shown in FIGS. 2(a) and 2(b), the porous body 110 has a truncated cone shape, and the through-hole 120 has a shape in which the porous body 110 fits.

[0026] The through hole 120 has an upper opening 121 located on the first surface 41A and a lower opening 122 located on the second surface 41B. The upper opening 121 and the lower opening 122 are circular in shape, and the center of the upper opening 121 and the center of the lower opening 122 overlap with each other in a plan view from a first direction perpendicular to the first surface 41A.

[0027] Also, the diameter of the lower opening 122 is larger than the diameter of the upper opening 121. The opening area of ​​the through hole 120 on a plane parallel to the first surface 41A increases linearly from the upper opening 121 to the lower opening 122. That is, the inner wall surface of the through hole 120 is an inclined surface inclined from the first direction so that the opening area of ​​the through hole 120 increases as it approaches the lower opening 122. In a plan view from the first direction, the entire upper opening 121 is inside the lower opening 122. The upper opening 121 is an example of a first opening, and the lower opening 122 is an example of a second opening. In this case, the first distance is 0, and the second distance is equal to the thickness of the dielectric member 41.

[0028] As described above, the porous body 110 has a truncated cone shape. The porous body 110 has a third surface 113 that is flush with the first surface 41A and a fourth surface 114 that is flush with the second surface 41B. The shape and size of the third surface 113 are approximately the same as the shape and size of the upper opening 121. The shape and size of the fourth surface 114 are approximately the same as the shape and size of the lower opening 122. The porous body 110 has a first portion 131 located inside the upper opening 121 and a second portion 132 connected to the first portion 131 and located outside the upper opening 121 in a plan view from the first direction. The cross-sectional area of ​​the cross section perpendicular to the first direction of the porous body 110 is larger than the opening area of ​​the upper opening 121, except for the area of ​​the third surface 113.

[0029] As described above, the through hole 120 communicates with the gas passage 16. The lower opening 122 of the through hole 120 and the fourth surface 114 of the porous body 110 are formed larger than the opening 16A of the gas passage 16 on the electrostatic adsorption member 30 side in a plan view.

[0030] In the substrate fixing device 1 according to the first embodiment, the porous body 110 has a first portion 131 and a second portion 132. Therefore, even if the adhesive force between the porous body 110 and the dielectric member 41 is reduced, it is possible to suppress the detachment of the porous body 110 from the through-hole 120. That is, even if a cooling gas is supplied to the through-hole 120 from the gas passage 16 provided in the base plate 10 and gas pressure is applied to the porous body 110, the second portion 132 cannot pass through the upper opening 121 and is constrained within the through-hole 120, so that it is possible to suppress the detachment of the porous body 110 from the through-hole 120.

[0031] Therefore, it is possible to suppress the detachment of the porous body 110 from the through-holes 120, and to suppress the abnormal discharge caused by the detachment of the porous body 110.

[0032] Furthermore, since the porous body 110 is bonded to the dielectric member 41, excellent bonding strength can be obtained between the porous body 110 and the dielectric member 41. In particular, when the dielectric member 41 is made of ceramic, it is easy to obtain good bonding strength.

[0033] It is preferable that the porous body 110 contacts the dielectric member 41 made of ceramic. This is because good bonding strength can be obtained, and the difference in thermal expansion coefficient between the two materials is small, making it possible to reduce thermal stress.

[0034] Furthermore, since the third surface 113 of the porous body 110 is flush with the first surface 41A, substantially no gap is generated between the third surface 113 and the substrate when the substrate is attracted to the electrostatic attraction member 30. This makes it possible to suppress discharge between the porous body 110 and the substrate.

[0035] The method of providing the porous body 110 in the through-hole 120 is not limited. For example, the porous body 110 may be formed by sintering an inorganic material, and fixed to the inner surface of the through-hole 120 with an adhesive or the like. Alternatively, the porous body 110 may be formed in the through-hole 120 by applying a paste containing inorganic material particles, preferably spherical particles, to the inside of the through-hole 120 and then firing the paste. As the inorganic material, ceramic, glass, or the like may be used. In particular, it is preferable that the main component of the porous body 110 and the main component of the dielectric member 41 are the same.

[0036] In the former method, strictly speaking, the porous body 110 is formed slightly smaller than the through-hole 120, and the gap is filled with an adhesive or the like, but in the latter method, the porous body 110 can be directly bonded to the inner wall surface of the through-hole 120. Therefore, according to the latter method, the proportion of the porous body 110 in the through-hole 120 can be increased. In addition, in the latter method, by applying the paste from the lower opening 122, it is easy to fill the through-hole 120 with the paste without generating a gap.

[0037] Note that, as long as at least a portion of upper opening 121 is inside lower opening 122 in plan view from the first direction, at least a portion of upper opening 121 may be outside lower opening 122.

[0038] Second embodiment Next, a second embodiment will be described. The second embodiment differs from the first embodiment in terms of the shapes of the through holes and the porous body. Here, the shapes of the porous body and the through holes in the second embodiment will be described. Fig. 3 is a cross-sectional view showing an electrostatic adsorption member 30 in the second embodiment.

[0039] In the second embodiment, the base 31 has a plurality of porous bodies 210 instead of the plurality of porous bodies 110. Moreover, a plurality of through holes 220 are formed in the dielectric member 41 instead of the plurality of through holes 120. The through holes 220 communicate with the gas passage 16 of the base plate 10. One porous body 210 is provided in each of the through holes 220.

[0040] As shown in FIG. 3, the porous body 210 has a shape composed of multiple, for example, three, overlapping cylinders, with the cross-sectional area decreasing toward the first surface 41A side, and the through hole 220 has a shape into which the porous body 210 fits.

[0041] Through hole 220 has upper opening 221 located on first surface 41A and lower opening 222 located on second surface 41B. Upper opening 221 and lower opening 222 are circular in shape, and the center of upper opening 221 and the center of lower opening 222 overlap in a plan view from a first direction perpendicular to first surface 41A.

[0042] Also, the diameter of the lower opening 222 is larger than the diameter of the upper opening 221. The opening area of ​​the through hole 220 in a plane parallel to the first surface 41A increases stepwise from the upper opening 221 to the lower opening 222. That is, the inner wall surface of the through hole 220 has a stepped surface. In a plan view from the first direction, the entire upper opening 221 is inside the lower opening 222. The upper opening 221 is an example of a first opening, and the lower opening 222 is an example of a second opening. In this case, the first distance is 0, and the second distance is equal to the thickness of the dielectric member 41.

[0043] As described above, the porous body 210 has a shape formed by stacking a plurality of, for example, three, cylinders, with the cross-sectional area being smaller toward the first surface 41A side. The porous body 210 has a third surface 213 that is flush with the first surface 41A, and a fourth surface 214 that is flush with the second surface 41B. The shape and size of the third surface 213 are approximately the same as the shape and size of the upper opening 221. The shape and size of the fourth surface 214 are approximately the same as the shape and size of the lower opening 222. The porous body 210 has a first portion 231 located inside the upper opening 221, and a second portion 232 connected to the first portion 231 and located outside the upper opening 221, in a plan view from the first direction. The cross-sectional area of ​​the porous body 210 in a cross section perpendicular to the first direction is larger than the opening area of ​​the upper opening 221, except for the area of ​​the third surface 213.

[0044] As described above, the through hole 220 communicates with the gas passage 16. The lower opening 222 of the through hole 220 and the fourth surface 214 of the porous body 210 are formed larger than the opening 16A of the gas passage 16 on the electrostatic adsorption member 30 side in a plan view.

[0045] In the substrate fixing device according to the second embodiment, the porous body 210 has a first portion 231 and a second portion 232. Therefore, even if the adhesive force between the porous body 210 and the dielectric member 41 is reduced, it is possible to suppress the detachment of the porous body 210 from the through-hole 220. That is, even if a cooling gas is supplied to the through-hole 220 from the gas path 16 provided in the base plate 10 and gas pressure is applied to the porous body 210, the second portion 232 cannot pass through the upper opening 221 and is constrained within the through-hole 220, so that it is possible to suppress the detachment of the porous body 210 from the through-hole 220.

[0046] The method of providing the porous body 210 in the through-hole 220 is not limited. For example, the porous body 210 may be formed by sintering an inorganic material, and fixed to the inner surface of the through-hole 220 with an adhesive or the like. Alternatively, the porous body 210 may be formed in the through-hole 220 by applying a paste containing inorganic material particles, preferably spherical particles, to the inside of the through-hole 220 and then firing the paste. In the latter method, applying the paste from the lower opening 222 makes it easy to fill the through-hole 220 with the paste without generating voids.

[0047] Third embodiment Next, a third embodiment will be described. The third embodiment differs from the first embodiment and the like in terms of the shapes of the through holes and the porous body. Here, the shapes of the porous body and the through holes in the third embodiment will be described. Fig. 4 is a cross-sectional view showing an electrostatic adsorption member 30 in the third embodiment.

[0048] In the third embodiment, the base 31 has a plurality of porous bodies 310 instead of the plurality of porous bodies 110. Moreover, a plurality of through holes 320 are formed in the dielectric member 41 instead of the plurality of through holes 120. The through holes 320 communicate with the gas passage 16 of the base plate 10. One porous body 310 is provided in each of the through holes 320.

[0049] As shown in FIG. 4, the porous body 310 has a drum-like shape, and the through-hole 320 has a shape in which the porous body 310 fits.

[0050] Through hole 320 has upper opening 321 located on first surface 41A, lower opening 322 located on second surface 41B, and intermediate opening 323 located between upper opening 321 and lower opening 322. Upper opening 321, lower opening 322, and intermediate opening 323 are each circular, and the center of upper opening 321, the center of lower opening 322, and the center of intermediate opening 323 overlap with each other in a plan view from a first direction perpendicular to first surface 41A.

[0051] Also, the diameter of the lower opening 322 and the diameter of the upper opening 321 are approximately equal. The diameters of the upper opening 321 and the lower opening 322 are larger than the diameter of the intermediate opening 323. The opening area of ​​the through hole 320 on a surface parallel to the first surface 41A linearly decreases from the upper opening 321 to the intermediate opening 323, and linearly increases from the intermediate opening 323 to the lower opening 322. That is, the inner wall surface of the through hole 320 is an inclined surface inclined from the first direction such that the opening area of ​​the through hole 320 decreases as it approaches the intermediate opening 323 between the upper opening 321 and the intermediate opening 323, and the opening area of ​​the through hole 320 increases as it approaches the lower opening 322 between the intermediate opening 323 and the lower opening 322. In a plan view from the first direction, the entire intermediate opening 323 is inside the lower opening 322. The intermediate opening 323 is an example of a first opening, and the lower opening 322 is an example of a second opening. In this case, the first distance is the distance between the first surface 41A and the intermediate opening 323, and the second distance is equal to the thickness of the dielectric member 41.

[0052] As described above, the porous body 310 has a drum-shaped shape. The porous body 310 has a third surface 313 that is flush with the first surface 41A and a fourth surface 314 that is flush with the second surface 41B. The shape and size of the third surface 313 are approximately the same as the shape and size of the upper opening 321. The shape and size of the fourth surface 314 are approximately the same as the shape and size of the lower opening 322. The porous body 310 has a first portion 331 located inside the middle opening 323 in a plan view from the first direction, and a second portion 332 connected to the first portion 331 and located outside the middle opening 323 on the lower opening 322 side of the middle opening 323. The cross-sectional area of ​​the cross section perpendicular to the first direction of the porous body 310 is larger on the lower opening 322 side of the middle opening 323 than the opening area of ​​the middle opening 323.

[0053] As described above, the through hole 320 communicates with the gas passage 16. The lower opening 322 of the through hole 320 and the fourth surface 314 of the porous body 310 are formed larger than the opening 16A of the gas passage 16 on the electrostatic adsorption member 30 side in a plan view. The lower opening 322 of the through hole 320 and the fourth surface 314 of the porous body 310 may be formed smaller than the opening 16A of the gas passage 16 on the electrostatic adsorption member 30 side in a plan view.

[0054] In the substrate fixing device according to the third embodiment, the porous body 310 has a first portion 331 and a second portion 332. Therefore, even if the adhesive force between the porous body 310 and the dielectric member 41 is reduced, it is possible to suppress the detachment of the porous body 310 from the through-hole 320. That is, even if a cooling gas is supplied to the through-hole 320 from the gas passage 16 provided in the base plate 10 and gas pressure is applied to the porous body 310, the second portion 332 cannot pass through the intermediate opening 323 and is constrained within the through-hole 320, so that it is possible to suppress the detachment of the porous body 310 from the through-hole 320.

[0055] There is no limitation on the method for providing the porous body 310 in the through-hole 320. For example, the porous body 310 may be formed in the through-hole 320 by applying a paste containing inorganic material particles, preferably spherical particles, to the inside of the through-hole 320 and then firing the paste.

[0056] (Fourth embodiment) Next, a fourth embodiment will be described. The fourth embodiment differs from the first embodiment and the like in terms of the shapes of the through holes and the porous body. Here, the shapes of the porous body and the through holes in the fourth embodiment will be described. Fig. 5 is a cross-sectional view showing an electrostatic adsorption member 30 in the fourth embodiment.

[0057] In the fourth embodiment, the base 31 has a plurality of porous bodies 410 instead of the plurality of porous bodies 110. Moreover, a plurality of through holes 420 are formed in the dielectric member 41 instead of the plurality of through holes 120. The through holes 420 communicate with the gas passage 16 of the base plate 10. One porous body 410 is provided in each of the through holes 420.

[0058] As shown in FIG. 5, porous body 410 has a side surface on which a spiral groove is formed like a male thread, and through hole 420 has an inner wall surface on which a spiral groove is formed like a female thread, and through hole 420 has a shape into which porous body 410 fits.

[0059] Through hole 420 has upper opening 421 located on first surface 41A and lower opening 422 located on second surface 41B. Upper opening 421 and lower opening 422 are circular in shape, and the center of upper opening 421 and the center of lower opening 422 substantially overlap each other in a plan view from a first direction perpendicular to first surface 41A.

[0060] In a plan view from a first direction perpendicular to the first surface 41A, a bottom curve connecting the bottoms of the spiral grooves formed on the side surface of the through hole 420 is annular, and a top curve connecting the tops between adjacent grooves in the first direction is also annular. The area of ​​the bottom curve is larger than the area of ​​the top curve. In a plan view from a first direction perpendicular to the first surface 41A, a top opening 423 corresponding to the top curve constituting one revolution of the ring is an example of a first opening, and a bottom opening 424 located on the lower opening 422 side from the top opening 423 and corresponding to the bottom curve constituting one revolution of the ring is an example of a second opening. In this case, the first distance is the distance between the first surface 41A and the part of the top opening 423 closest to the first surface 41A, and the second distance is the distance between the first surface 41A and the part of the bottom opening 424 closest to the first surface 41A. In a plan view from the first direction, the entire top opening 423 is inside the bottom opening 424.

[0061] As described above, the porous body 410 has a side surface on which a spiral groove is formed like a male screw. The porous body 410 has a third surface 413 that is flush with the first surface 41A and a fourth surface 414 that is flush with the second surface 41B. The shape and size of the third surface 413 are approximately the same as the shape and size of the upper opening 421. The shape and size of the fourth surface 414 are approximately the same as the shape and size of the lower opening 422. The porous body 410 has a first portion 431 located inside the top opening 423 in a plan view from the first direction, and a second portion 432 that is connected to the first portion 431 and located outside the top opening 423 on the lower opening 422 side of the top opening 423.

[0062] As described above, the through hole 420 communicates with the gas passage 16. The lower opening 422 of the through hole 420 and the fourth surface 414 of the porous body 410 are formed larger than the opening 16A of the gas passage 16 on the electrostatic adsorption member 30 side in a plan view. The lower opening 422 of the through hole 420 and the fourth surface 414 of the porous body 410 may be formed smaller than the opening 16A of the gas passage 16 on the electrostatic adsorption member 30 side in a plan view.

[0063] In the substrate fixing device according to the fourth embodiment, the porous body 410 has a first portion 431 and a second portion 432. Therefore, even if the adhesive force between the porous body 410 and the dielectric member 41 is reduced, it is possible to suppress the detachment of the porous body 410 from the through-hole 420. That is, even if a cooling gas is supplied to the through-hole 420 from the gas passage 16 provided in the base plate 10 and gas pressure is applied to the porous body 410, the second portion 432 cannot pass through the top opening 423 and is constrained within the through-hole 420, so that it is possible to suppress the detachment of the porous body 410 from the through-hole 420.

[0064] The method of providing the porous body 410 in the through hole 420 is not limited. For example, the porous body 410 may be formed by sintering an inorganic material, and fixed to the inner surface of the through hole 120 with an adhesive or the like. The porous body 410 can be screwed into the through hole 420. Alternatively, the porous body 410 may be formed in the through hole 420 by applying a paste containing inorganic material particles, preferably spherical particles, to the inside of the through hole 420 and then firing the paste.

[0065] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims. [Explanation of symbols]

[0066] 1 Board fixing device 10 Base plate 16 Gas Line 30 Electrostatic attraction member 31 Base 41 Dielectric materials 110, 210, 310, 410 Porous body 113, 213, 313, 413 3rd page 114, 214, 314, 414 4th side 120, 220, 320, 420 Through holes 121, 221, 321, 421 Top opening 122, 222, 322, 422 Lower opening 131, 231, 331, 431 Part 1 132, 232, 332, 432 Part 2 323 Middle opening

Claims

1. a dielectric member having a first surface and a second surface opposite to the first surface, the dielectric member having a through hole formed therein that penetrates from the first surface to the second surface; a porous body provided in the through hole and having a third surface flush with the first surface; having The through hole is a first opening spaced a first distance from the first surface in a first direction perpendicular to the first surface; a second opening spaced apart from the first surface in the first direction by a second distance greater than the first distance; having In a plan view from the first direction, at least a portion of the first opening is located inside the second opening, The porous body, when viewed in a plan view from the first direction, a first portion located inside the first opening; a second portion connected to the first portion and positioned outside the first opening; having An electrostatic attraction member, characterized in that, in a plan view from the first direction, the first opening is entirely inside the second opening.

2. 2. The electrostatic attraction member according to claim 1, wherein the through holes are filled with the porous body.

3. 3. The electrostatic attraction member according to claim 1, wherein the first opening is located in the first surface.

4. 4. The electrostatic attraction member according to claim 1, wherein the second opening is located in the second surface.

5. 5. The electrostatic attraction member according to claim 1, wherein the dielectric member has an electrostatic electrode built therein.

6. An electrostatic attraction member according to any one of claims 1 to 5, a base plate adhered to the second surface; A substrate fixing device comprising:

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