Composite sealant

Abstract

In addition to resistance to plasma and process gases, this invention provides a composite sealing material that can withstand temperature changes (contraction and expansion) between room temperature and cryogenic temperatures. [Solution] This composite seal material 1 comprises an annular first seal material 10, a second seal material 20, and a third seal material 30, wherein the third seal material 30 includes a third seal first end 30a and a third seal second end 30b, the third seal first end 30a is located on the circumference closer to the second seal second end 20b than to the second seal first end 20a, and the third seal second end 30b is located on the circumference closer to the second seal second end 20 The first end 20a of the second seal is located closer to the first end 20a of the second seal than b is located, and the first end 30a of the third seal and the second end 30b of the third seal are positioned such that there is a gap L1 of a predetermined length on the circumference of the second seal material 20. The first seal material 10 is made of a material that is more elastically deformable than the second seal material 20 and the third seal material 30, and the second seal material 20 and the third seal material 30 are made of a harder material than the first seal material 10.

Description

Technical Field

[0001] This invention relates to the structure of a composite sealing material.

Background Art

[0002] For example, an electrostatic chuck is used as a holding device for holding a semiconductor wafer inside a vacuum chamber of a semiconductor manufacturing apparatus. The electrostatic chuck is formed by joining a plate-like material made of a material containing ceramics and a base material made of metal with a joint using an adhesive. The electrostatic chuck utilizes the electrostatic attraction generated when a voltage is applied to the chuck electrode to adsorb and hold the semiconductor wafer on the surface of the plate-like material.

[0003] In the semiconductor manufacturing process, it is necessary to prevent the outer peripheral surface of the joint portion of the above-described electrostatic chuck from being exposed to plasma, process gas, etc. and deteriorating. Therefore, a technique of arranging a protective ring on the outer peripheral surface of the joint portion is known.

[0004] Such techniques are disclosed in Japanese Patent Application Laid-Open No. 2021-044304 (Patent Document 1), Japanese Patent Application Laid-Open No. 2021-044305 (Patent Document 2), Japanese Patent Application Laid-Open No. 2021-100050 (Patent Document 3), and Japanese Patent Application Laid-Open No. 2022-175820 (Patent Document 4), etc.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, the manufacturing process for semiconductor devices has increasingly demanded ultra-low temperature processes ranging from -20°C to -120°C, in addition to conventional high-temperature processes, due to the need for further improvements in processing accuracy and more precise control of chemical reactions. As a result, the protective rings described above require composite sealing materials that can withstand not only high temperatures against plasma and process gases, but also temperature changes (contraction and expansion) between high and ultra-low temperatures.

[0007] This invention was made to solve the above-mentioned problems, and aims to provide a composite sealing material that can withstand not only high temperatures against plasma and process gases, but also temperature changes (contraction and expansion) between high and cryogenic temperatures. [Means for solving the problem]

[0008] [1] A seal comprising: a first seal material arranged in an annular manner around a central axis; a second seal material arranged to cover the radially outer side of the first seal material for a predetermined length on the circumference; and a third seal material arranged to cover the radially outer side of the first seal material and to overlap one second seal first end and the other second seal second end of the second seal material, wherein the third seal material includes a third seal first end and a third seal second end, and the third seal first end extends further than the second seal first end on the circumference A composite seal material wherein the second end of the third seal is located on the side of the second end, the second end of the third seal is located on the circumference closer to the first end of the second seal than the second end of the second seal, the first end of the third seal and the second end of the third seal are positioned such that there is a gap of a predetermined length on the circumference of the second seal material, the first seal material is made of a material that is more elastically deformable than the second seal material and the third seal material, and the second seal material and the third seal material are made of a harder material than the first seal material.

[0009] [2] The composite seal material according to [1], wherein the second seal material is arranged radially outside the first seal material, and the first end of the third seal and the second end of the third seal are arranged radially outside the second seal material such that they have the gap described above.

[0010] [3] When the first seal material, the second seal material, and the third seal material are cut along a virtual plane including the central axis, the end face shapes of the first seal material, the first seal material has a first convex region on its radially outer side that engages with the radially inner side of the third seal material, and the third seal material has a first concave region on its radially inner side that receives and engages with the first convex region, and in the region of the first seal material where the second seal material is placed The composite seal material according to [2], wherein the radially outer side of the first seal material has a second convex region that engages with the radially inner side of the second seal material, the radially inner side of the second seal material has a second concave region that receives and engages with the second convex region, and in the region where the third seal material is arranged radially outside the second seal material, the radially outer side of the second seal material has a third convex region that can receive and engage with the first concave region provided radially inside the third seal material.

[0011] [4] The composite seal material according to [3], wherein the first end of the third seal and the second end of the third seal are arranged radially outside the second seal material such that they have the gap described above, and the length of the gap and the length of the circumference of the third seal material are adjusted such that when the third seal material is most contracted, the first end of the third seal and the second end of the third seal are in a state of merely contact or have the smallest gap without contact, and when the third seal material is most stretched, the gap between the first end of the third seal and the second end of the third seal is the largest, and the first end of the third seal and the second end of the third seal are located radially outside the second seal material. [Effects of the Invention]

[0012] According to this composite sealing material, in addition to the high-temperature resistance to plasma, process gas, etc., it is possible to provide a composite sealing material that can also withstand temperature changes (shrinkage and expansion) between high temperatures and extremely low temperatures.

Brief Description of the Drawings

[0013] [Figure 1] It is a perspective view showing the overall configuration of the composite sealing material in Embodiment 1. [Figure 2] It is a partially enlarged perspective view of the region surrounded by II in FIG. 1. [Figure 3] It is an exploded perspective view of the composite sealing material shown in FIG. 3. [Figure 4] It is an end view taken along the line IV-IV in FIG. 3. [Figure 5] It is an end view taken along the line V-V in FIG. 3. [Figure 6] It is an end view taken along the line VI-VI in FIG. 3. [Figure 7] It is an end view taken along the line VII-VII in FIG. 3. [Figure 8] It is an end view taken along the line VIII-VIII in FIG. 2. [Figure 9] It is an end view taken along the line IX-IX in FIG. 2. [Figure 10] It is an end view taken along the line X-X in FIG. 2. [Figure 11] It is a first region view showing the state where the composite sealing material in Embodiment 1 is mounted on the holding device. [Figure 12] It is a second region view showing the state where the composite sealing material in Embodiment 1 is mounted on the holding device. [Figure 13] It is a third region view showing the state where the composite sealing material in Embodiment 1 is mounted on the holding device. [Figure 14] It is a schematic diagram showing the problems of the composite sealing material in Embodiment 1. [Figure 15] It is a partially enlarged perspective view corresponding to the region surrounded by II in FIG. 1 of the composite sealing material in Embodiment 2. [Figure 16]It is an exploded perspective view of the composite sealing material shown in FIG. 15. [Figure 17] It is an end view taken in the direction of the arrow XVII-XVII in FIG. 16. [Figure 18] It is an end view taken in the direction of the arrow XVIII-XVIII in FIG. 15. [Figure 19] It is a schematic diagram showing the operation and effect of the composite sealing material in Embodiment 2.

Embodiments for Carrying Out the Invention

[0014] The composite sealing material in this embodiment will be described below with reference to the drawings. In each of the embodiments described below, when referring to the number, quantity, etc., unless otherwise specified, the scope of the present invention is not necessarily limited to the number, quantity, etc. Also, for the same parts and corresponding parts, the same reference numerals may be assigned, and duplicate explanations may not be repeated. The end views shown in FIGS. 4 to 13, 17, and 18 are end views when viewed along a virtual plane including the central axis a1. The direction in which the central axis a1 extends means the upward and downward directions in the drawing.

[0015] [Embodiment 1: Composite Sealing Material 1] Referring to FIGS. 1 to 3, the composite sealing material 1 of this embodiment will be described. The composite sealing material 1 of this embodiment is used as a protective ring of an electrostatic chuck as a holding device for holding a semiconductor wafer inside a vacuum chamber of a semiconductor manufacturing apparatus. Examples of use as a protective ring of an electrostatic chuck will be described later.

[0016] The composite sealing material 1 has an annular shape as a whole. The composite sealing material 1 includes a first sealing material 10 arranged annularly around the central axis a1, a second sealing material 20 arranged so as to cover the outer side in the radial direction at a predetermined length on the circumference of the first sealing material 10, and a third sealing material 30 that covers the outer side in the radial direction of the first sealing material 10 and is arranged such that one first end portion 20a and the other second end portion 20b of the second sealing material 20 overlap.

[0017] The third seal material 30 includes a third seal first end 30a and a third seal second end 30b. The third seal first end 30a is located on the circumference closer to the second seal second end 20b than to the second seal first end 20a. The third seal second end 30b is located on the circumference closer to the second seal first end 20a than to the second seal second end 20b.

[0018] The first end 30a of the third seal and the second end 30b of the third seal are positioned on the circumference of the second sealing material 20 such that there is a predetermined gap (gap L1 in Figure 2).

[0019] The dimensions of the first seal material 10, the second seal material 20, and the third seal material 30 are appropriately designed according to the size of the electrostatic chuck to which they are applied. For example, if the outermost circumference length of the first seal material 10 is D1 (mm), the circumference length of the second seal material 20 is preferably about 12% to 24% of D1. Also, the gap L1, which will be described later, is preferably about 4% to 6% of D1. Note that these dimensional relationships are merely examples, and the most appropriate dimensional relationships are selected according to the specifications required for the composite seal material 1.

[0020] According to the arrangement described above, as shown in Figure 3, the composite seal material 1 has a notch region 10c of a predetermined circumferential length on the outer side of the first seal material 10, with the first end 10a and the second end 10b of the first seal exposed.

[0021] The second seal material 20 is fitted into the notched region 10c of the first seal material 10, with the first end 20a of the second seal facing the first end 10a of the first seal, and the second end 20b of the second seal facing the second end 10b of the first seal.

[0022] Furthermore, a third seal material 30 is positioned outside the first seal material 10 and the second seal material 20 in the circumferential direction, and the third seal material 30 covers the areas where the first end 20a of the second seal and the first end 10a of the first seal face each other, and the areas where the second end 20b of the second seal and the second end 10b of the first seal face each other. The first end 30a and the second end 30b of the third seal material 30 are located outside the second seal material 20 and are positioned to have a predetermined gap (gap L1 in Figure 2).

[0023] The dimensions of the first seal material 10, the second seal material 20, and the third seal material 30 are designed appropriately according to the size of the electrostatic chuck to which they are applied. For example, if the circumference of the outermost part of the first seal material 10 is D1 (mm), the circumference of the second seal material 20 is preferably about 12% to 24% of D1. The circumference of the notch area 10c is made about 1% to 2% longer than the circumference of the second seal material 20. Also, the gap L1, which will be described later, is preferably about 4% to 6% of D1. Note that these dimensional relationships are merely examples, and the most appropriate dimensional relationships are selected according to the specifications required for the composite seal material 1.

[0024] [End face shape of each sealing material] Next, with reference to Figures 4 to 7, the end face shapes of the first seal material 10, the second seal material 20, and the third seal material 30 when cut along a virtual plane containing the central axis a1 will be described. Since the end face shape of each seal material is symmetrical with respect to a virtual plane VP extending perpendicular to the central axis a1, the following description will focus on the end face shape on the upper side with respect to the illustrated virtual plane VP.

[0025] [End face shape of the region of the first sealing material 10 where the notched region 10c is not provided] Figure 4 shows the end face shape of the region of the first sealing material 10 where the notched region 10c is not provided. The first sealing material 10 has a flat portion 101 parallel to the central axis a1 at the outermost radial position. The end of the flat portion 101 has a rounded corner portion 102. The end of the rounded corner portion 102 has an inclined wall portion 103 that gradually slopes toward the virtual plane VP in the direction of the central axis a1.

[0026] The end of the inclined wall portion 103 has a curved portion 104 that is recessed inward. The end of the curved portion 104 has a flat portion 105 that is parallel to the central axis a1. The end of the flat portion 105 has a rounded corner portion 106. The rounded corner portion 106 is located further away from the virtual plane VP than the rounded corner portion 102. The end of the rounded corner portion 106 has a wall portion 107 that is parallel to the virtual plane VP.

[0027] The end of the wall portion 107 has a curved portion 108. The end of the curved portion 108 has a flat portion 109 that is parallel to the central axis a1. The end of the flat portion 109 has a corner radius portion 110. The corner radius portion 110 is located further away from the virtual plane VP than the corner radius portion 106. The end of the corner radius portion 110 has a wall portion 111 that is parallel to the virtual plane VP.

[0028] The end of the wall portion 111 has an inclined wall portion 112 that gradually slopes toward the virtual plane VP in the direction of the central axis a1. The end of the inclined wall portion 112 has a wall portion 113 that is parallel to the virtual plane VP. The end of the wall portion 113 has a tapered portion 114 that gradually slopes toward the virtual plane VP in the direction of the central axis a1. The end of the tapered portion 114 has a flat portion 115 that is parallel to the central axis a1 at the innermost circumference in the radial direction.

[0029] The first sealing material 10 having the above configuration has a wall portion 111 and a flat portion 115 that constitute a region that contacts a holding device described later.

[0030] [First convex region 50a] The first sealing material 10 has a base end face 10x formed by the region on the central axis a1 side of the flat portion 109, a first region 10y formed by the region between the flat portion 105 and the flat portion 109, and a second region 10z formed by the region between the flat portion 101 and the flat portion 105. The first convex region 50a is formed by the first region 10y and the second region 10z.

[0031] [Shape of the end face of the region where the notched area 10c of the first sealing material 10 is provided] Figure 5 shows the end face shape of the region in which the notched area 10c of the first sealing material 10 is provided. The first sealing material 10 has a flat portion 121 parallel to the central axis a1 at the outermost radial position. The end of the flat portion 121 has a corner radius portion 122. The end of the corner radius portion 122 has an inclined wall portion 123 that gradually slopes toward the virtual plane VP in the direction of the central axis a1.

[0032] The end of the inclined wall portion 123 has a curved portion 124 that is recessed inward. The end of the curved portion 124 has a flat portion 125. The end face shape of the flat portion 125 extending toward the central axis a1 is the same as the shape of the first sealing material 10 described above.

[0033] [Second convex region 50b] The first sealing material 10 has a third region 10w, which is formed by the region between the flat portion 125 and the flat portion 121. The second convex region 50b is formed by the third region 10w.

[0034] [End face shape of the second sealing material 20] Figure 6 shows the end face shape of the second sealing material 20. The second sealing material 20 has a flat portion 201 parallel to the central axis a1 at the outermost radial position. The end of the flat portion 201 has a tapered portion 202 (cut surface). The end of the tapered portion 202 has a wall portion 203 parallel to the virtual plane VP. The end of the wall portion 203 has a curved portion 204 that is recessed inward. The end of the curved portion 204 has a flat portion 205 parallel to the central axis a1.

[0035] The end of the flat section 205 has a wall section 206 parallel to the virtual plane VP. The end of the wall section 206 has a flat section 207 parallel to the central axis a1. The end of the flat section 207 has a corner radius section 208. The end of the corner radius section has an inclined wall section 209 that gradually slopes away from the virtual plane VP in the direction away from the central axis a1. The end of the inclined wall section 209 has a curved section 210. The end of the curved section 210 has a flat section 211 located parallel to the flat section 201.

[0036] [Third convex region 50c / second concave region 60b] A third convex region 50c is defined by a convex outer surface defined by a flat portion 201, a tapered portion 202, and a wall portion 203. A second concave region 60b is defined by a concave inner surface defined by a flat portion 211, a curved portion 210, and an inclined wall portion 209.

[0037] [End face shape of the third sealing material 30] Figure 7 shows the end face shape of the third sealing material 30. The third sealing material 30 has a flat portion 301 parallel to the central axis a1 at the outermost radial position. The end of the flat portion 301 has a tapered portion 302 (cut surface). The end of the tapered portion 302 has a tapered portion 303 (cut surface). The angle of inclination of the tapered portion 302 and the tapered portion 303 with respect to the virtual plane VP is greater for the tapered portion 302.

[0038] The tapered portion 303 has a wall portion 304 at its end that is parallel to the virtual plane VP. The wall portion 304 has a flat portion 305 at its end that is parallel to the central axis a1. The flat portion 305 has a wall portion 306 at its end that is parallel to the wall portion 304. The wall portion 306 has a curved portion 307 at its end. The curved portion 307 has a flat portion 308 at its end that is parallel to the central axis a1.

[0039] The end of the flat section 308 has a rounded corner section 309. The end of the rounded corner section 309 has an inclined wall section 310 that gradually slopes away from the virtual plane VP in the direction away from the central axis a1. The end of the inclined wall section 310 has a curved section 311. The end of the curved section 311 has a flat section 312 that is located parallel to the flat section 301.

[0040] [First concave region 60a] The first concave region 60a is defined by the concave inner surface defined by the wall portion 306, the curved portion 307, the flat portion 308, the corner radius portion 309, the inclined wall portion 310, the curved portion 311, and the flat portion 312.

[0041] [Combining the first sealant 10, the second sealant 20, and the third sealant 30] Referring to Figures 8 to 10, a composite sealing material 1 formed by combining and engaging the first sealing material 10, the second sealing material 20, and the third sealing material 30 having the above-described configurations will be explained.

[0042] Figure 8 shows an end view taken along the line VIII-VIII in Figure 2. In this region, the engagement state between the first seal material 10 and the third seal material 30 will be explained. In the region where the notched region 10c of the first seal material 10 is not provided (the region excluding the region where the second seal material 20 is placed), the radially outer side of the first seal material 10 has a first convex region 50a as described above, and the radially inner side of the third seal material 30 has a first concave region 60a as described above, with the first concave region 60a receiving the first convex region 50a.

[0043] The first region 10y of the first convex region 50a is held and engaged by the wall portion 306 of the first concave region 60a. Furthermore, the second region 10z of the first convex region 50a is held and engaged by the inclined wall portion 310 of the first concave region 60a. In particular, the inclined wall portion 103 and the inclined wall portion 310 of the second region 10z have a shape that gradually inclines toward the virtual plane VP in the direction of the central axis a1, resulting in the second region 10z fitting in a wedge effect with respect to the shape defined by the inclined wall portion 103. As a result, the engagement state of the third seal material 30 with respect to the first seal material 10 is maintained. Furthermore, circumferential sliding of the third seal material 30 relative to the first seal material 10 is permitted.

[0044] Figure 9 shows an end view taken along the line IX-IX in Figure 2. The combination of the first seal material 10 and the second seal material 20 in the notched region 10c of the first seal material 10 will now be explained. The radially outer side of the first seal material 10 has a second convex region 50b, as described above, and the radially inner side of the second seal material 20 has a second concave region 60b, as described above, and the second concave region 60b has a shape that receives the second convex region 50b.

[0045] The third region 10w of the second convex region 50b is held by the inclined wall portion 209 of the second concave region 60b. In particular, the inclined wall portion 123 and the inclined wall portion 209 of the third region 10w have a shape that gradually inclines toward the virtual plane VP in the direction of the central axis a1, resulting in the third region 10w fitting into the shape defined by the inclined wall portion 209 in a wedge effect. As a result, the engagement state of the second seal material 20 with respect to the first seal material 10 is maintained.

[0046] Figure 10 shows an end view taken along the line XX in Figure 2. The combination of the second seal material 20 and the third seal material 30 will now be described. As described above, the radially outer side of the second seal material 20 is defined as the third convex region 50c, and the first concave region 60a provided on the radially inner side of the third seal material 30 has a configuration (labyrinth structure) that receives the third convex region 50c. The third convex region 50c is held by engaging with the wall portion 306 of the first concave region 60a. Furthermore, it allows the third seal material 30 to slide circumferentially relative to the second seal material 20.

[0047] [Materials for the first sealant 10, the second sealant 20, and the third sealant 30] The composite sealant 1 is preferably made of a material that is highly elastic and rigid. In particular, the composite sealant 1 in this embodiment needs to withstand temperature changes (contraction and expansion) between room temperature and cryogenic temperatures.

[0048] However, a single material that satisfies both of these characteristics does not currently exist, although it is being diligently researched. Therefore, the first seal material 10 is made of a material that is more elastically deformable than the second seal material 20 and the third seal material 30, and the second seal material 20 and the third seal material 30 are made of a material that is harder than the first seal material 10.

[0049] The desired properties for the first sealing material 10 include high elastic deformation, good contact surface sealing performance, good permeable sealing performance, ease of mold molding, and a material that retains its elasticity even at low temperatures (-20°C to -120°C) and high temperatures (150°C or higher). For example, silicone rubber may be used.

[0050] The elastomer materials relating to this disclosure may encompass all types of elastomers, but among them, materials with a particularly low Tg (glass transition temperature) and that can maintain flexibility even in low-temperature environments are preferably used.

[0051] Examples of silicone rubbers include vinyl methyl silicone (methyl vinyl silicone rubber: VMQ), phenyl vinyl methyl silicone rubber (PVMQ), and fluorine-containing vinyl methyl silicone (FVMQ).

[0052] Examples of fluoroelastomers include fluororubber (FKM: low-temperature grade) and perfluoroelastomer (FFKM), as well as vinylidene fluoride (VDF)-hexafluoropropylene (HFP) copolymer, VDF-HFP-tetrafluoroethylene (TFE) copolymer, TFE-propylene (Pr) copolymer, VDF-Pr-TFE copolymer, ethylene (E)-TFE-perfluoromethyl vinyl ether (PMVE) copolymer, VDF-TFE-PMVE copolymer, and VDF-PMVE copolymer.

[0053] Examples of ethylene-based rubbers include ethylene propylene rubber (EPDM).

[0054] Examples of nitrile-based rubbers include nitrile rubber (NBR: low-temperature type) and hydrogenated nitrile rubber (HNBR: low-temperature type).

[0055] Examples of thermoplastic elastomers include thermoplastic polyurethane elastomers (TPU: low-temperature compatible grades).

[0056] These materials may be used individually, blended with other elastomers, or used in combination of two or more types; however, they may be used in combination.

[0057] The desired properties for the second seal material 20 and the third seal material 30 are that they have high radical resistance (plasma resistance), do not decompose easily when exposed to fluorine-based radical gases, have a low Young's modulus, have a wide elastic deformation range before reaching the yield point (elastic deformation possible up to about 2% at room temperature), are easy to process, have little increase in Young's modulus even at low temperatures (-120°C), and do not melt even at high temperatures (above 150°C). For example, PTFE may be used.

[0058] The plasma-resistant resin material described herein exhibits excellent durability even in plasma exposure environments and contributes to low etch rate, low outgassing, and reduced metal contamination. It can encompass all types of resin materials, but among them, materials with particularly high plasma resistance are preferably used.

[0059] Examples of fluororesins include polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), perfluoroethylene propene copolymer (FEP), ethylene tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), and polychlorotrifluoroethylene (PCTFE).

[0060] Other resin materials include polyphenylene sulfide (PPS), polyimide (PI), polyamide-imide (PAI), polyetherimide (PEI), polybenzimidazole (PBI), polyetherketone (PEK), polyetheretherketone (PEEK), ultra-high molecular weight polyethylene (UHPE), and liquid crystal polymer (LCP).

[0061] These materials may be used individually or in combination of two or more types, and are not limited to those described above.

[0062] [Usage status of composite sealant 1] Referring to Figures 11 to 13, the usage state of the composite sealing material 1 having the above-described configuration will be explained. As an example, the use of the composite sealing material 1 as a protective ring in an electrostatic chuck 1000 used as a holding device for holding semiconductor wafers inside the vacuum chamber of a conductor manufacturing apparatus will be explained.

[0063] As shown in Figure 11, the electrostatic chuck 1000 is formed by joining a plate-shaped body 1100 made of a material containing ceramics and a base body 1200 made of metal, using an adhesive layer at a joint 1300.

[0064] This electrostatic chuck 1000 is provided with an annular recess 1110 for attaching a protective ring to prevent the exposed joint 1300 from being exposed to plasma, process gases, etc. The composite sealing material 1 is fitted into this annular recess 1110.

[0065] Since the first sealing material 10 is made of a material with excellent elasticity, when fitting the first sealing material 10 into the annular recess 1110, the diameter of the first sealing material 10 can be enlarged to easily insert it into the annular recess 1110.

[0066] On the other hand, since the third sealing material 30 is made of a material with poor expansion and contraction properties, the first end 30a and the second end 30b of the third seal can be separated to enlarge the diameter of the third sealing material 30 and easily insert it into the annular recess 1110.

[0067] As shown in Figures 11 to 13, when the composite seal material 1 is housed in the annular recess 1110, the length H1 in the direction in which the central axis a1 of the composite seal material 1 extends (see Figure 8) is set to be greater than the length h1 of the annular recess 1110, so that the composite seal material 1 can be fitted into the annular recess 1110 while compressed.

[0068] Furthermore, when the composite sealant 1 is fitted into the annular recess 1110, the dimensions of the composite sealant 1 are designed such that the wall portion 304 of the third sealant 30 is in pressure contact with the plate-like body 1100 and the base body 1200. Also, in the region where the third sealant 30 is absent and the second sealant 20 is exposed (the region of the gap L1), the dimensions of the composite sealant 1 are designed such that the wall portion 206 of the second sealant 20 is in pressure contact with the plate-like body 1100 and the base body 1200.

[0069] As a result, a reaction force to the compressive force of the composite sealing material 1 acts on the electrostatic chuck 1000 (arrow in the figure). This allows the composite sealing material 1 to adhere tightly to the inner wall of the annular recess 1110. This configuration makes it possible to prevent plasma, process gas, and other substances from entering the annular recess 1110.

[0070] [Effects / Effects] Referring again to Figure 2, the third sealing material 30 covers the first end 10a of the first seal, the first end 20a of the second seal, the second end 10b of the first seal, and the second end 20b of the second seal, and the first end 20a of the third seal and the second end 30b of the third sealing material 30 are located on the outer surface side of the second sealing material 20 with a gap L1 between them.

[0071] When this composite seal material 1 is used in a temperature environment ranging from high temperatures to extremely low temperatures (-20°C to -120°C), the first seal material 10 exhibits small expansion and contraction in the circumferential direction due to the material properties described above. On the other hand, the second seal material 20 and the third seal material 30 exhibit large contraction in the circumferential direction due to the material properties described above. In particular, since the third seal material 30 has a long circumference, the contraction of the third seal material 30 cannot be ignored compared to the contraction of the second seal material 20.

[0072] Therefore, as described above, in order to absorb the amount of shrinkage of the third sealing material 30, the first end 20a of the third seal and the second end 30b of the third seal of the third sealing material 30 are arranged on the outer surface side of the second sealing material 20 so as to provide a gap L1.

[0073] Specifically, the length of the gap L1 and the length of the third seal material 30 along its circumference are adjusted such that, when the third seal material 30 is in its most contracted state (used at extremely low temperatures), the first end 30a and the second end 30b of the third seal are in only slight contact or not in contact at all, resulting in the smallest possible gap. When the third seal material 30 is in its most stretched state (used at room temperature), the gap between the first end 30a and the second end 30b of the third seal is at its largest, but the first end 30a and the second end 30b of the third seal are positioned radially outside the second seal material 20.

[0074] The gap L2 between the first end 10a of the first seal and the first end 20a of the second seal, and the gap L2 between the second end 10b of the first seal and the second end 20b of the second seal, are provided taking into consideration the amount of expansion and contraction corresponding to the length of the circumference of the second sealing material 20.

[0075] Thus, with the composite sealing material 1 having the above configuration, the first sealing material 10 experiences only small changes in circumference even with temperature changes (contraction and expansion) between high and cryogenic temperatures relative to the joint portion 1300 of the holding device 100, thus preventing contact with the plasma or process gas at the joint portion 1300. On the other hand, the second sealing material 20 and the third sealing material 30, located on the outer circumference of the first sealing material 10, protect the first sealing material 10 from contact with the plasma or process gas, thereby suppressing deterioration of the first sealing material 10.

[0076] [Embodiment 2] As shown in Figure 14, in the configuration of the composite seal material 1 described above, a passage S is created between the flat portion 201 of the second seal material 20 and the inner surface of the third seal material 30, between the second seal material 20 covered by the third seal material 30.

[0077] In this case, if the second sealing material 20 is not provided, the surface of the first sealing material 10 will be exposed through the gap in the third sealing material 30, and the surface of the first sealing material 10 will be directly exposed to plasma, process gas, etc. On the other hand, with the configuration of Embodiment 1 described above, as described above, the passage S is provided, so it is necessary to go through two bends before reaching the surface of the first sealing material 10. As a result, compared to the case where the penetration path is linear, the deterioration of the surface of the first sealing material 10 due to exposure to plasma, process gas, etc. is suppressed.

[0078] However, more preferably, it is desirable to more effectively suppress deterioration of the surface of the first sealing material 10 due to exposure to plasma, process gas, etc. Therefore, the composite sealing material 1A in Embodiment 2 shown below makes it possible to more effectively suppress deterioration of the surface of the first sealing material 10.

[0079] Referring to Figures 15 to 18, the form of the composite seal material 1A in Embodiment 2 will be described. The forms of the first seal material 10 and the third seal material 30 are the same as those of the composite seal material 1 in Embodiment 1, and only the form of the second seal material 20A differs from that of the composite seal material 1 in Embodiment 1.

[0080] As shown in Figure 17, the second sealing material 20A of this embodiment differs from the second sealing material 20 of Embodiment 1 in the shape of the third convex region 50c. Specifically, on the radially outer side of the flat portion 201, there is a flat portion 220 parallel to the central axis a1 at the outermost radial position. The end of the flat portion 220 has a corner radius portion 221. The end of the corner radius portion 221 has a wall portion 222 that gradually slopes toward the virtual plane VP in the direction of the central axis a1. The end of the wall portion 222 has a curved portion 223 that is recessed inward. This curved portion 223 is in communication with the flat portion 201.

[0081] As shown in Figure 18, by using the second seal material 20A having this configuration, the third convex region 50c of the second seal material 20A is located within the first concave region 60a of the third seal material 30, in the region surrounded by the wall portion 222. In particular, the inclined wall portion 103 and the wall portion 222 have a configuration in which they gradually incline toward the virtual plane VP in the direction of the central axis a1, resulting in the second region 10z fitting into the configuration defined by the wall portion 222 in a wedge effect. As a result, the engagement state of the third seal material 30 with respect to the second seal material 20 is maintained, and the passage S described above can be filled by the third convex region 50c.

[0082] As a result, as shown in Figure 19, this composite sealing material 1A makes it possible to block the gap leading to the passage S, and more effectively suppresses the deterioration of the surface of the first sealing material 10 due to exposure to plasma, process gas, etc., compared to the configuration of the composite sealing material 1 of Embodiment 1.

[0083] In this embodiment, the second seal material 20 is positioned radially outside the first seal material 10, and the first end 30a and second end 30b of the third seal are positioned radially outside the second seal material 20 with a predetermined gap (gap L1 in Figure 2). However, the configuration is not limited to this. For example, the first end 30a and second end 30b of the third seal are positioned radially outside the first seal material 10 with a predetermined gap (gap L1 in Figure 2), and the second seal material 20 may be positioned so as to cover the first end 30a and second end 30b of the third seal.

[0084] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0085] 1 Composite seal material, 10 First seal material, 10a, 20a, 30a First end, 10b, 20b, 30b Second end, 10c Notch area, 10x Base end face, 10y First area, 10z Second area, 10w Third area, 20, 20A Second seal material, 30 Third seal material, 50a First convex area, 50b Second convex area, 50c Third convex area, 60a First concave area, 60b Second concave area, 100 Holding device, 101, 105, 109, 115, 121, 125, 201, 205, 207, 211, 301, 305, 308, 312 Flat section: 102, 106, 110, 122, 208, 309, 103, 112, 123, 209, 310 Inclined wall section: 104, 108, 124, 204, 210, 307, 311 Curved section: 107, 111, 113, 203, 206, 304, 306 Wall section: 114, 202, 302, 303 Tapered section: 1000 Electrostatic chuck: 1100 Plate-like body: 1110 Annular recess: 1200 Base material: L1 Distance, VP Virtual plane, a1 Central axis.

Claims

1. A first sealing material arranged in a ring around a central axis, A second sealing material is arranged to cover the radially outer side of the first sealing material over a predetermined length on its circumference, A third sealing material is provided which covers the radially outer side of the first sealing material and is positioned to overlap one first end of the second seal and the other second end of the second seal of the second sealing material, Equipped with, The third sealing material includes the first end of the third seal and the second end of the third seal. The third seal first end is located on the circumference closer to the second seal second end than to the second seal first end, The third seal's second end is located on the circumference closer to the second seal's first end than to the second seal's second end. The first end of the third seal and the second end of the third seal are positioned on the circumference of the second sealing material such that there is a gap of a predetermined length between them. The first sealing material is made of a material that is more elastically deformable than the second and third sealing materials. The second and third sealing materials are made of harder materials than the first sealing material. Composite sealant.

2. The second sealing material is positioned radially outside the first sealing material. The first end of the third seal and the second end of the third seal are positioned radially outward of the second seal material such that they have the aforementioned gap. The composite sealing material according to claim 1.

3. The end face shapes of the first seal material, the second seal material, and the third seal material when cut along a virtual plane including the central axis are as follows: In the region of the first sealing material excluding the region where the second sealing material is placed, The radially outer side of the first sealing material has a first convex region that engages with the radially inner side of the third sealing material. The radially inner side of the third sealing material has a first concave region that receives and engages with the first convex region, In the region of the first sealing material where the second sealing material is positioned, The radially outer side of the first sealing material has a second convex region that engages with the radially inner side of the second sealing material. The radially inner side of the second sealing material has a second concave region that receives and engages with the second convex region. In the region where the third sealing material is positioned radially outside the second sealing material, The radially outer side of the second sealing material has a third convex region that can be received and engaged with the first concave region provided on the radially inner side of the third sealing material. The composite sealing material according to claim 2.

4. When the first end of the third seal and the second end of the third seal are arranged radially outward of the second seal material such that they have the gap, The length of the gap and the length of the third sealing material along its circumference are, In the most contracted state of the third seal material, the first end of the third seal and the second end of the third seal are in a state of mere contact, or in the state of the smallest gap where they are not in contact. The third seal is adjusted so that when the third seal is in its most stretched state, the gap between the first end and the second end of the third seal is largest, and the first end and the second end of the third seal are located radially outside the second seal. The composite sealing material according to claim 3.

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