Holding device

Abstract

To provide a technique for suppressing fracture of a fiber-containing layer in a holding device having a fiber-containing layer formed by at least one type of metal and inorganic material.SOLUTION: A holding device has an inorganic substrate having a plate section, a fiber section, and an inorganic binder section and having a bonding surface to be bonded to the plate section, a base portion, and a bonding section for bonding the inorganic substrate and the base section, the inorganic binder section has an inorganic binder including an inorganic resin that is mainly composed of an inorganic material and is at least partially between the plate section and the fiber section, the fiber section has a plurality of fibers formed by at least one of metal and inorganic material, and has a first fiber section with one or more fibers extending in a first direction along the bonding surface and a second fiber section with one or more fibers extending in a second direction that is different from the first direction and along the bonding surface.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a holding device for holding an object. [Background technology]

[0002] Electrostatic chucks, for example, are used as holding devices for holding objects such as wafers during semiconductor manufacturing. The electrostatic chuck includes a plate-shaped member on which the object is placed, a base member supporting the plate-shaped member, and a joint that joins the plate-shaped member to the base member. When an electrostatic chuck is used in a high-temperature process, for example, at 250°C or higher, the joint formed with a silicone adhesive or the like can be easily degraded by heat. To address this issue, a technology has been proposed in which the joint is made into two layers, with the joint layer (first joint layer) placed on the plate-shaped member side having higher thermal insulation properties than the other joint layer (second joint layer), thereby suppressing heat dissipation from the plate-shaped member to the second joint layer (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-068219 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, the first bonding layer contains fibers made of at least one of metal and inorganic material. In the technology described in Patent Document 1, the short fibers are piled up and partially overlap each other, and the bonds between the short fibers are weak. Therefore, temperature changes accompanying the use of the electrostatic chuck can cause the bonds between the short fibers to break, leading to the fracture of the first bonding layer.

[0005] Such a problem is not limited to electrostatic chucks, but is a common problem among holding devices such as heater devices, susceptors, and mounting tables for vacuum devices such as CVD (chemical vapor deposition), PVD (physical vapor deposition), and PLD (pulsed laser deposition).

[0006] The present invention has been made to solve the above-mentioned problems, and aims to provide a technology for suppressing breakage of a fiber-containing layer in a holding device having a fiber-containing layer formed from at least one of metal and inorganic material. [Means for solving the problem]

[0007] The present invention has been made to solve the above-mentioned problems, and can be realized in the following forms.

[0008] (1) According to one aspect of the present invention, there is provided a holding device for holding an object, the holding device comprising: a plate-shaped inorganic substrate having a plate-shaped portion, a fiber portion, and an inorganic binder portion, the plate-shaped inorganic substrate having a bonding surface to be bonded to the plate-shaped portion; a plate-shaped base portion disposed on the inorganic substrate opposite the plate-shaped portion; and a bonding portion disposed between the inorganic substrate and the base portion and bonding the inorganic substrate to the base portion, the inorganic binder portion being made of an inorganic binder mainly composed of an inorganic material and including an inorganic resin bonded to the plate-shaped portion, the inorganic binder portion being present at least partially between the plate-shaped portion and the fiber portion, the fiber portion being made of a plurality of fibers formed of at least one of a metal and an inorganic material, the first fiber portion having one or more fibers extending in a first direction along the bonding surface, and the second fiber portion having one or more fibers extending in a second direction along the bonding surface that is different from the first direction.

[0009] According to this configuration, the holding device has an inorganic substrate, which functions as an insulating plate, suppressing heat dissipation from the plate-shaped portion to the joint, thereby suppressing thermal deterioration of the joint. Because the inorganic substrate has a fiber portion composed of multiple fibers and an inorganic binder portion, the fibers can be fixed together by the inorganic binder, preventing separation of the fibers when stress is generated in the inorganic substrate. Furthermore, because the first fiber portion and the second fiber portion extend in different directions, the anisotropy of thermal expansion caused by temperature changes in the holding device can be reduced, preventing uneven stress generation in the inorganic substrate. As a result, breakage of the inorganic substrate can be suppressed.

[0010] (2) In the holding device of the above embodiment, the first fiber parts and the second fiber parts may intersect. Since the first fiber parts and the second fiber parts intersect, the bonding strength between the fibers is improved, and breakage of the inorganic substrate can be suppressed.

[0011] (3) In the holding device of the above embodiment, the fiber portion may be a cloth-like material including a woven or knitted portion of the first fiber portion and the second fiber portion. This increases the number of intersections between the first fiber portion and the second fiber portion, thereby further strengthening the fixation of the fibers. Furthermore, the strength against a force acting along the bonding surface of the inorganic substrate can be further improved. As a result, breakage of the inorganic substrate can be further suppressed.

[0012] (4) In the holding device of the above aspect, the fiber portion may be disposed within the inorganic binder portion. In this way, the entire bonding surface of the inorganic substrate is made of the inorganic binder, thereby improving the bonding strength between the plate-like portion and the inorganic substrate.

[0013] (5) In the holding device of the above aspect, the inorganic binder portion may contain inorganic particles having a thermal expansion coefficient smaller than that of the inorganic resin. In this way, thermal expansion of the inorganic substrate can be suppressed, and fracture of the inorganic substrate due to temperature changes in the holding device can be suppressed.

[0014] (6) In the holding device of the above embodiment, the plate-like portion and the inorganic substrate may have different thermal expansion coefficients. If the plate-like portion and the inorganic substrate have different thermal expansion coefficients, stress is likely to occur in the inorganic substrate as the temperature of the holding device changes, but as described above, breakage of the inorganic substrate can be suppressed.

[0015] The present invention can be realized in various forms, for example, in the form of a semiconductor manufacturing apparatus including a holding device, a manufacturing method for a holding device, a method for forming an inorganic substrate, and the like. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view schematically illustrating an external configuration of an electrostatic chuck according to an embodiment. [Figure 2] FIG. 2 is an explanatory view schematically showing an XZ cross-sectional configuration of the electrostatic chuck. [Figure 3] FIG. 2 is an explanatory diagram conceptually showing the planar configuration of an inorganic substrate. [Figure 4] FIG. 2 is an explanatory diagram conceptually illustrating an enlarged cross-sectional configuration of an inorganic substrate. [Figure 5] FIG. 1 is an explanatory diagram of cracks occurring in an inorganic substrate. [Figure 6] FIG. 1 is an explanatory diagram conceptually illustrating an inorganic substrate of a comparative example. [Figure 7] 1A to 1C are explanatory diagrams conceptually illustrating a part of a method for manufacturing an electrostatic chuck. [Figure 8] FIG. 10 is an explanatory diagram showing an exploded configuration of an inorganic substrate of an electrostatic chuck according to a second embodiment. [Figure 9] FIG. 10 is an explanatory diagram conceptually showing the configuration of an inorganic substrate of an electrostatic chuck according to a third embodiment. [Figure 10] FIG. 10 is an explanatory view schematically showing an XZ cross-sectional configuration of an electrostatic chuck according to a fourth embodiment. [Figure 11] FIG. 10 is an explanatory view schematically showing an XZ cross-sectional configuration of an electrostatic chuck according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] First Embodiment FIG. 1 is a perspective view schematically illustrating the external configuration of an electrostatic chuck 10 according to an embodiment. FIG. 2 is an explanatory diagram schematically illustrating the XZ cross-sectional configuration of the electrostatic chuck 10. In FIGS. 1 and 2, mutually orthogonal X, Y, and Z axes are shown to identify directions. In FIG. 2, the positive Y-axis direction is the direction toward the back of the page. For convenience, in this specification, the positive Z-axis direction is referred to as the upward direction and the negative Z-axis direction is referred to as the downward direction, but the electrostatic chuck 10 may actually be installed in an orientation different from these orientations. The electrostatic chuck 10 according to this embodiment is also referred to as a "holding device."

[0018] The electrostatic chuck 10 is a device that attracts and holds an object (e.g., a wafer W) by electrostatic attraction, and is used, for example, to fix the wafer W in a vacuum chamber of a semiconductor manufacturing device. The electrostatic chuck 10 includes a plate-shaped portion 100 and a base portion 200 that are arranged in a vertical direction (Z-axis direction), an inorganic substrate 300 that is arranged between the plate-shaped portion 100 and the base portion 200 and functions as a heat insulating material, and a joining portion 400 that joins the inorganic substrate 300 and the base portion 200.

[0019] The plate-shaped member 100 is a plate-shaped member having a first surface S1 with a substantially circular, flat shape (FIG. 1). In this embodiment, the first surface S1 of the plate-shaped member 100 functions as a mounting surface on which a wafer W is placed. The plate-shaped member 100 is a dense body whose main component is ceramics (e.g., alumina, aluminum nitride, etc.), known as fine ceramics or new ceramics. In this specification, when a specific component is "mainly a component" or "mainly a material that forms the component," it means that the content of the specific component is 50% by volume or more. In other embodiments, the plate-shaped member 100 may be formed mainly from a material other than ceramic, such as a resin such as polyimide or transparent glass.

[0020] The diameter of the first surface S1 of the plate-shaped portion 100 is not particularly limited, but is, for example, approximately 50 mm to 500 mm (usually approximately 200 mm to 350 mm). The thickness of the plate-shaped portion 100 is not particularly limited, but is preferably 2 mm or more and 10 mm or less. This is because it is possible to suppress the occurrence of cracks, internal gaps, voids, etc. in the plate-shaped portion 100. In this specification, when a numerical range is indicated using "to" it is assumed that the range includes both the lower limit and the upper limit unless otherwise specified. For example, the expression "10 to 20" includes both the lower limit of "10" and the upper limit of "20". In other words, "10 to 20" has the same meaning as "10 or more and 20 or less".

[0021] An attraction electrode 130 (FIG. 2) made of a conductive material (e.g., tungsten, molybdenum, etc.) is disposed inside the plate-shaped portion 100. The shape of the attraction electrode 130 as viewed in the Z-axis direction is, for example, substantially circular. When a voltage is applied to the attraction electrode 130 from a power source (not shown), an electrostatic attraction force is generated, and the wafer W is attracted and fixed to the first surface S1 of the plate-shaped portion 100 by this electrostatic attraction force.

[0022] A heater may be disposed inside the plate-shaped portion 100 below the chucking electrode 130 (on the negative Z-axis side). The heater may be configured as a metallized layer made of tungsten, molybdenum, or the like. The heater may have a spiral or disk shape when viewed in the Z-axis direction, for example.

[0023] The base portion 200 is a plate-like member having a substantially circular, flat shape and a larger diameter than the plate-like portion 100. The base portion 200 may contain at least one metal selected from the group consisting of aluminum, magnesium, molybdenum, titanium, tungsten, and nickel. Among the above-mentioned metals, molybdenum, titanium, and tungsten have relatively small thermal expansion coefficients. Therefore, using at least one of these metals to form the base portion 200 is desirable because it minimizes the difference in thermal expansion coefficients between the base portion 200 and the plate-like portion 100. Note that, in this specification, the term "thermal expansion coefficient" refers to the "linear expansion coefficient." Furthermore, magnesium has a relatively small Young's modulus. Therefore, using magnesium to form the base portion 200 is desirable because it reduces thermal stress generated in the base portion 200. Furthermore, aluminum has a relatively high thermal conductivity, is easy to process, and is inexpensive. Therefore, using aluminum to form the base portion 200 is desirable because it enhances the cooling efficiency of the base portion 200 for the plate-like portion 100 and the wafer W and reduces the manufacturing cost of the electrostatic chuck 10. From the viewpoint of suppressing manufacturing costs while increasing the cooling efficiency of the base portion 200, it is desirable that the base portion 200 contain a high metal content, and it is desirable that the base portion 200 be mainly composed of metal. For example, it is desirable that the base portion 200 contain 90 mass % or more of aluminum, which is highly versatile (for example, be made of an aluminum alloy such as A6061 or A5052). However, the base portion 200 may also contain components other than metal, such as ceramic. The diameter of the base portion 200 is, for example, approximately 220 mm to 550 mm (usually 220 mm to 350 mm), and the thickness of the base portion 200 is, for example, approximately 20 mm to 40 mm.

[0024] A coolant flow path 210 ( FIG. 2 ) is formed inside the base portion 200. When a wafer W held on the plate-shaped portion 100 of the electrostatic chuck 10 is processed using plasma, heat is input from the plasma to the wafer W, causing the temperature of the wafer W to rise. When a coolant (e.g., a fluorine-based inert liquid or water) flows through the coolant flow path 210 formed in the base portion 200, the base portion 200 is cooled. The plate-shaped portion 100 is cooled by heat transfer between the base portion 200 and the plate-shaped portion 100 via the bonding portion 400 and the inorganic substrate 300, and the wafer W held on the first surface S1 of the plate-shaped portion 100 is cooled. This allows temperature control of the wafer W. In other embodiments, the base portion may not have a coolant flow path formed therein, and may be cooled from the outside.

[0025] The inorganic substrate 300 is a substantially circular, flat plate-like member having the same diameter as the first surface S1 of the plate-like portion 100, and functions as a heat insulating material. The thickness of the inorganic substrate 300 is not particularly limited, but is preferably, for example, 0.15 mm or more and 1.0 mm or less. The thermal expansion coefficient of the inorganic substrate 300 is not particularly limited, but may be different from that of the plate-like portion 100.

[0026] The thermal expansion coefficient can be measured by the following method. A known thermal expansion coefficient measurement device (e.g., Rigaku Corporation TMA8311) can be used. A sample is cut to a size of 18 mm long, 3 mm wide, and 4 mm thick. A compressive load of 100 mN is applied in the longitudinal direction, and the sample is heated to 400°C at a rate of 10°C / min in a nitrogen atmosphere with a nitrogen flow rate of 100 ml / min, while the change in length in the longitudinal direction is measured. The thermal expansion coefficient between 30°C and 300°C can be measured by subtracting the length at 30°C from the length at 300°C and dividing the result by the temperature difference of 270°C.

[0027] The thermal conductivity of the inorganic material constituting the inorganic substrate 300 is not particularly limited, but is preferably 1.8 W / mK or less, and more preferably 0.9 W / mK or less. Here, the thermal conductivity is the thermal conductivity at room temperature (20°C). The thermal conductivity can be calculated from the thermal diffusivity using the laser flash method. The density used in the calculation is measured using the Archimedes method. The sample may be molded independently or cut from a holding device, and the results will be the same. The inorganic substrate 300 will be described in detail later.

[0028] The bonding portion 400 is a substantially circular, flat, plate-like member having the same diameter as the inorganic substrate 300, and bonds the inorganic substrate 300 to the base portion 200. The bonding portion 400 is formed from an adhesive, and for example, an adhesive containing an organic substance such as acrylic or polyimide, or silicone as a main component can be used.

[0029] Silicone adhesives can be prepared, for example, by mixing polydimethylsiloxane with a crosslinking agent, a silane coupling agent, a curing catalyst, and a filler. The filler can be at least one of alumina, silica, aluminum nitride, boron nitride, carbon black, graphite, carbon nanotubes, silicon carbide, silicon nitride, iron oxide, and magnesium oxide. Sheet- or varnish-type silicone adhesives can be used to bond the inorganic substrate 300 and the base portion 200. When used in sheet form, the sheet-type silicone adhesive is cut to a predetermined shape and then attached to the inorganic substrate 300 integrated with the plate-like portion 100 and the base portion 200 in a vacuum. Furthermore, the inorganic substrate 300 integrated with the plate-like portion 100 and the base portion 200 can be bonded to each other by bonding them together in a vacuum via the sheet-type silicone adhesive and curing at a temperature of 100°C or higher. When a varnish-like silicone adhesive is used, it can be applied to the base portion 200 by screen printing, bonded to the inorganic substrate 300 integrated with the plate-like portion 100 in a vacuum, and cured at a temperature of 100° C. or higher, thereby bonding the inorganic substrate 300 to the base portion 200. Here, a resin wall may be formed on the base portion 200 to prevent the adhesive from flowing out.

[0030] The thickness of the joint 400 is not particularly limited, but is preferably 200 μm to 800 μm. A thinner joint 400 is better in terms of heat dissipation, but if it is too thin, it will not be possible to alleviate the difference in thermal expansion between the plate-like portion 100 and the base portion 200. If the thickness of the joint 400 is within the above range, it will be possible to properly dissipate heat and also to alleviate the difference in thermal expansion between the plate-like portion 100 and the base portion 200.

[0031] The thermal conductivity of the joint 400 is not particularly limited, but is preferably 0.2 to 1.5 W / (m·K). While a high thermal conductivity of the joint 400 is preferable, adding a large amount of thermally conductive filler (e.g., alumina, aluminum nitride, boron nitride, etc.) to increase the thermal conductivity makes the joint hard and difficult to stretch, which may cause breakage due to temperature changes or reduce the ability to relax stress caused by the temperature difference between the plate-like portion 100 and the base portion 200. Setting the thermal conductivity of the joint 400 within the above range ensures stress relaxation ability and allows efficient heat conduction.

[0032] Fig. 3 is an explanatory diagram conceptually showing the planar configuration of inorganic substrate 300. Fig. 4 is an explanatory diagram conceptually showing an enlarged cross-sectional configuration of inorganic substrate 300. Fig. 4 is a cross-sectional view conceptually showing an enlarged E1 portion in Fig. 2.

[0033] 3, the inorganic substrate 300 includes a fiber portion 330 and an inorganic binder portion 340. Specifically, the fiber portion 330 includes a plurality of fibers 311, 321 The fiber portion 330 comprises a first fiber portion 310 having one or more fibers 311 extending in a first direction (the X-axis direction in this embodiment) along the bonding surface S2, and a second fiber portion 320 having one or more fibers 321 extending in a second direction (the Y-axis direction in this embodiment) different from the first direction and along the bonding surface S2. As shown in the figure, the fiber portion 330 is a so-called "plain weave" woven fabric in which the first fiber portions 310 and the second fiber portions 320 alternately cross. The first fiber portions 310 and the second fiber portions 320 are perpendicular to each other.

[0034] Fiber 311, 321is formed from at least one of metal and inorganic materials, and examples of the fiber material include inorganic fibers, metal fibers, and carbon fibers. Examples of inorganic fibers include fibers of calcium carbonate, alumina, soda glass, and quartz glass, as well as rock wool (artificial mineral fibers composed of silicon dioxide and calcium oxide). Examples of metal fibers include fibers of stainless steel, aluminum, copper, brass, and titanium. Examples of carbon fibers include carbon fibers, and fibers of carbons such as carbon nanotubes, graphene, and graphite. Examples of glass fibers include E-glass, C-glass, D-glass, S-glass, T-glass, ECR-glass, AR-glass, and VMP-glass. E-glass, which has a thermal expansion coefficient relatively close to that of alumina, is preferred.

[0035] The inorganic substrate 300 has a fiber portion 330, a fiber 311, 321 has a tensile strength greater than that of the inorganic binder part 340, and can therefore improve the tensile strength of the inorganic substrate 300. The diameter of the fibers is not particularly limited, but is preferably 5 to 10 μm. This allows the material strength of the inorganic substrate 300 to be within an appropriate range.

[0036] The inorganic binder portion 340 is made of an inorganic binder containing an inorganic resin that is mainly composed of an inorganic material and that bonds with the plate-shaped portion 100. In other words, the inorganic binder portion 340 is a hardened product of the inorganic binder. The inorganic resin forms a continuous layer as shown in the figure. The inorganic resin also functions as an adhesive and is bonded with the plate-shaped portion 100. In other words, the inorganic binder functions as both a filler and an adhesive. I haveThe inorganic resin is an inorganic polymer containing a small amount of organic components. Examples of inorganic resins that can be used include inorganic polymer silicone resins such as polyalkylsiloxane, polymethylsiloxane, polyalkylphenylsiloxane, and polymethylphenylsiloxane; dialkyldialkoxysilanes such as dimethyldialkoxysilane, phenylmethyldialkoxysilane, methyl-n-propyldialkoxysilane, ethylmethyldialkoxysilane, and ethylphenyldialkoxysilane; alkyltrialkoxysilanes such as phenyltrimethoxysilane, phenyltriethoxysilane, methyltrimethoxysilane, and methyltriethoxysilane; alkoxytrialkylsilanes such as methoxytrimethylsilane, ethoxytrimethylsilane, methoxytriethylsilane, ethoxytriethylsilane, and methoxytriphenylsilane; and tetraalkoxysilanes such as tetramethoxysilane and tetraethoxysilane, as well as condensates thereof. Other examples that may be used include inorganic cements such as Portland cement, sodium silicate (water glass), hydrous magnesium silicate (talc), colloidal silica, silica sol (for example, Snowtex (registered trademark) from Nissan Chemical Industries, Ltd.), and alumina sol.

[0037] 4, the fiber portion 330 is disposed within the inorganic binder portion 340. As will be described later, the inorganic substrate 300 is formed by impregnating the fiber portion 330 with the inorganic binder that forms the inorganic binder portion 340. Therefore, as shown in the figure, the inorganic binder portion 340 is present between the plurality of fibers 311 that form the first fiber portion 310, between the plurality of fibers 321 that form the second fiber portion 320, and between the first fiber portion 310 and the second fiber portion 320. Therefore, the inorganic binder filled between the fibers fixes the fibers together, and separation (falling apart) of the fiber bundle can be prevented.

[0038] Furthermore, the inorganic binder portion 340 is located between the plate-like portion 100 and the fiber portion 330 and forms the entire bonding surface S2 of the inorganic substrate 300. As described above, the inorganic resin contained in the inorganic binder portion 340 functions as an adhesive, thereby suppressing peeling at the bonding interface between the plate-like portion 100 and the inorganic substrate 300. In other embodiments, the inorganic binder portion 340 may be configured to be located at least partially between the plate-like portion 100 and the fiber portion 330. For example, by finely and partially bonding the plate-like portion 100 and the inorganic substrate 300 with the inorganic binder portion 340, stress generated in the inorganic substrate 300 due to temperature changes can be alleviated. However, a configuration in which the inorganic binder portion 340 is located entirely between the plate-like portion 100 and the fiber portion 330, as in this embodiment, is preferable because it improves the bonding strength between the plate-like portion 100 and the inorganic substrate 300.

[0039] In this embodiment, the inorganic binder portion 340 includes inorganic particles 350, as shown in the figure. The inorganic particles 350 are made of an inorganic material with a thermal expansion coefficient smaller than that of inorganic resin. Examples of inorganic particles 350 that can be used include carbon, alumina, silica, boron nitride, silicon nitride, calcium carbonate, and barium sulfate. Because the inorganic particles 350 have a thermal expansion coefficient smaller than that of inorganic resin, the thermal expansion of the inorganic binder portion 340 can be reduced. The particle diameter of the inorganic particles 350 is smaller than the diameter of the fibers, preferably 10 μm or less. Furthermore, the shape of the inorganic particles 350 is preferably irregular, rather than spherical, cubic, or the like.

[0040] 5 is an explanatory diagram of cracks occurring in inorganic substrate 300. FIG. 5 is a cross-sectional view conceptually showing a further enlarged portion of part E1 in FIG.

[0041] In the electrostatic chuck 10, stress is generated in the inorganic substrate 300 in the shear direction as described below. Here, the thermal expansion coefficient is as follows: plate-shaped portion 100<inorganic substrate 300<base portion 200. As described above, the bonding portion 400 is formed using an adhesive whose main component is an organic substance such as acrylic or polyimide, or silicone, and is made of a material with a low elastic modulus, so it can easily expand and contract, and the stress generated in the inorganic substrate 300 by the bonding portion 400 is small.

[0042] (1) Room temperature (e.g., 20°C), when not in operation: As described below, in the manufacture of the electrostatic chuck 10, the plate-shaped portion 100 and the inorganic substrate 300 are bonded by thermocompression bonding. Thereafter, when the inorganic substrate 300 and the base portion 200 are bonded by the bonding portion 400, the bonding portion 400 may be heated and cured at a temperature of 100°C or higher. At this time, the plate-shaped portion 100, the inorganic substrate 300, and the bonding portion 400 are each in a flat state during curing. When the electrostatic chuck 10 is at room temperature (e.g., 20°C) and in an unoperated state, the temperature is lower than during curing, and therefore each portion tends to shrink. At this time, since the thermal expansion coefficient of the plate-shaped portion 100 is lower than that of the inorganic substrate 300 as described above, the inorganic substrate 300 shrinks more, and tensile stress is generated at the bonding interface with the plate-shaped portion 100. (2) During operation (e.g., 250°C): During operation, the plate-shaped portion 100 receives heat from the plasma and reaches a high temperature (e.g., 250°C), while a coolant (e.g., 60°C) is supplied to the base portion 200, creating a temperature gradient in the stacking direction (Z-axis direction) of the electrostatic chuck 10, where the temperature decreases from the plate-shaped portion 100 toward the base portion 200. Therefore, shear stress occurs due to a difference in thermal expansion caused by the temperature difference within the inorganic substrate 300.

[0043] As such, shear stress occurs in the inorganic substrate 300 both when not in operation (at room temperature) and when in operation, which makes it susceptible to cracks C in the shear direction, as shown in Figure 4. Cracks C propagate primarily along the bonding surface S2 in areas with fewer fibers. This is thought to be due to thermal stress occurring along the bonding surface S2. Furthermore, as shown in Figure 5, cracks C also propagate in the perpendicular direction between fibers in some areas. It is thought that cracks occur due to delamination between the fibers and the inorganic binder caused by thermal contraction of the fibers and the inorganic binder. The above has been described for the case where the thermal expansion coefficient is plate-like portion 100 < inorganic substrate 300. However, even when the thermal expansion coefficient is plate-like portion 100 > inorganic substrate 300, temperature changes or temperature differences within the inorganic substrate 300 can cause shear stress due to the thermal expansion difference, potentially resulting in cracks C.

[0044] The effects of this embodiment will be described below in comparison with a comparative example. FIG. 6 is an explanatory diagram conceptually illustrating an inorganic substrate 300P of a comparative example. FIG. 6(A) shows an inorganic substrate 300P1 of a first comparative example, and FIG. 6(B) shows an inorganic substrate 300P2 of a second comparative example. In the inorganic substrate 300P1, the fibers 312 are short, and short fibers are stacked and partially entangled to form a sheet. An inorganic binder is filled in some of the continuous voids to bond the fibers together. Therefore, when stress is generated in the inorganic substrate 300P1, the bonds between the short fibers are broken, making the inorganic substrate 300P1 prone to fracture. In the inorganic substrate 300P2, the fibers 311 are long fibers extending along the first direction, as in the first embodiment. However, the inorganic substrate 300P2 does not have the fibers 321 of the inorganic substrate 300 of the first embodiment, and the fibers extend in only one direction. Therefore, the inorganic substrate 300P2 has high strength only in the direction in which the fibers extend (the first direction), resulting in anisotropy in strength. When stress is generated in the inorganic substrate 300P2, cracks are likely to occur between the fibers along the direction in which the fibers extend.

[0045] In this embodiment, the inorganic substrate 300 includes the fiber portion 330, and therefore, the fibers 311, 321expands and contracts, and can share the stress generated in the inorganic substrate 300, thereby reducing the stress generated in the inorganic binder section 340. Furthermore, because the fiber section 330 has the first fiber sections 310 and the second fiber sections 320 that are orthogonal to each other, the anisotropy of expansion and contraction that occurs with temperature changes in the inorganic substrate 300 can be reduced, and unevenness of the stress generated in the inorganic substrate 300 can be suppressed. Therefore, compared to the inorganic substrate 300P2 of the second comparative example shown in FIG. 6(B), the generation of cracks in the inorganic substrate 300 can be suppressed, and even if cracks do occur, the propagation of the cracks can be suppressed, thereby suppressing breakage of the inorganic binder section 340, i.e., breakage of the inorganic substrate 300.

[0046] As described above, the inorganic substrate 300 of this embodiment has the fiber portion 330, the fiber 311, 321 has a tensile strength greater than that of the inorganic binder portion 340, the tensile strength of the inorganic substrate 300 can be improved, and as a result, the breakage of the inorganic substrate 300 can be suppressed.

[0047] The fiber portion 330 of the inorganic substrate 300 is woven with first fiber portions 310 and second fiber portions 320, and the first fiber portions 310 and the second fiber portions 320 intersect with each other. The large number of intersections between the first fiber portions 310 and the second fiber portions 320 strengthens the fixation of the fibers to each other. Furthermore, the strength of the inorganic substrate 300 against a force acting in a direction along the bonding surface S2 can be improved. As a result, breakage of the inorganic substrate 300 can be suppressed.

[0048] Furthermore, in this embodiment, the fibers 311, 321 constituting the fiber portion 330 extend from end to end in a direction along the bonding surface S2 of the inorganic substrate 300. Therefore, compared to a case in which the fibers 311, 321 do not extend from end to end (are short) (the inorganic substrate 300P1 of the first comparative example shown in FIG. 6(A)), the strength of the inorganic substrate 300 can be improved. In other words, an inorganic substrate 300 that is resistant to stress can be provided.

[0049] Furthermore, in the inorganic substrate 300 of this embodiment, the fiber portion 330 is impregnated with an inorganic binder, and the inorganic resin is sufficiently filled between the fibers. 321 The bond is hard to break and the fiber bundles are hard to separate, so that fracture of the inorganic substrate 300 can be suppressed.

[0050] Furthermore, in the inorganic substrate 300 of this embodiment, the inorganic binder portion 340 contains inorganic particles 350 made of an inorganic material with a thermal expansion coefficient smaller than that of inorganic resin. Therefore, the thermal expansion of the inorganic binder portion 340 can be reduced compared to when the inorganic particles 350 are not provided. As a result, the difference in thermal expansion between the fiber portion 330 and the inorganic binder portion 340 can be reduced, and the occurrence of breakage inside the inorganic substrate 300 can be suppressed.

[0051] 7 is an explanatory diagram conceptually showing a part of a method for manufacturing the electrostatic chuck 10. The method for manufacturing the electrostatic chuck 10 is not particularly limited, but the electrostatic chuck 10 can be manufactured by, for example, the following method.

[0052] First, a ceramic substrate (plate-shaped portion 100), an inorganic substrate prepreg 301, and a base portion 200 are prepared. The prepreg is an intermediate material in which fibers are pre-impregnated with resin, and is obtained, for example, by impregnating a plain-woven fabric (fiber portion 330) of glass fiber with an inorganic binder solution, drying, and curing the material. The inorganic binder solution is prepared by mixing, for example, a solution of various silanes such as silicone resin, alkoxysilane, and silane coupling agent, silica (inorganic particles 350), an organic solvent, polysiloxane, water glass, etc. The plate-shaped portion 100 and the base portion 200 can be manufactured by known manufacturing methods, and therefore, a description of the manufacturing methods will be omitted here.

[0053] A plurality of prepregs 301 are laminated on the plate-shaped portion 100 and bonded by thermocompression to form a bonded body 103 in which the plate-shaped portion 100 and the inorganic substrate 300 are bonded together (FIG. 7(A)). The prepregs 301 have predetermined through-holes formed therein.

[0054] Before bonding, the surface of the plate-shaped member 100 may be subjected to plasma treatment. By modifying the surface of the plate-shaped member 100, the bonding strength of the inorganic binder can be improved.

[0055] Furthermore, an uneven shape may be provided on the surface of the plate-like portion 100 before bonding. By matching the uneven shape of the surface of the plate-like portion 100 with the uneven shape of the surface of the prepreg 301 of the inorganic substrate, the anchor effect can be enhanced, thereby improving the bonding strength of the bonded body 103.

[0056] Furthermore, before bonding, the surface of the plate-shaped member 100 may be subjected to blasting. Roughening the surface of the plate-shaped member 100 enhances the anchor effect, and the bonding strength of the bonded body 103 can be improved.

[0057] Furthermore, the plate-like portion 100 before bonding may be molded into a concave warp. When bonding to the smooth plate-like portion 100, the bonded body 103 may warp into a convex shape due to cure shrinkage of the inorganic substrate prepreg 301 and the difference in thermal expansion coefficient between the inorganic substrate prepreg 301 and the plate-like portion 100. By molding the plate-like portion 100 into a concave shape before bonding and then bonding the inorganic substrate prepreg 301, the bonded body 103 can be prevented from warping into a convex shape.

[0058] Furthermore, the plate-like portion 100 before bonding may be molded into a convex warp. When bonding to the smooth plate-like portion 100, the bonded body 103 may warp into a concave shape due to cure shrinkage of the inorganic substrate prepreg 301 and the difference in thermal expansion coefficient between the inorganic substrate prepreg 301 and the plate-like portion 100. By molding the plate-like portion 100 into a convex shape before bonding and then bonding the inorganic substrate prepreg 301, it is possible to prevent the bonded body 103 from warping into a concave shape.

[0059] Pores may also be present in the inorganic substrate 300. The pores have low thermal conductivity, which improves the heat insulating performance of the inorganic substrate 300 and can suppress a temperature rise in the bonding portion 400.

[0060] Next, the plate-like portion 100, the bonded body 103, and the base portion 200 are bonded together with a silicone adhesive to obtain the electrostatic chuck 10. Specifically, a first sheet-like adhesive 401 is attached to the surface of the bonded body 103 facing the inorganic substrate 300, and a second sheet-like adhesive 402 is attached to the base portion 200. The first sheet-like adhesive 401 and the second sheet-like adhesive 402 are then bonded together (FIG. 7(B)). The adhesive is then heated (100°C or higher) in this state to harden the adhesive, thereby forming the bonded portion 400 and obtaining the electrostatic chuck 10 (FIG. 7(C)). Note that the adhesive may be cured by adding moisture or by any other suitable method depending on the type of adhesive, regardless of whether it is heat curing or not.

[0061] The surface of the inorganic substrate 300 facing the bonding layer 400 may have irregularities that follow the undulations of the fiber part 330. Compared to a smooth surface, an irregular surface can increase the bonding area of the bonding layer 400, thereby increasing the bonding strength between the bonding part 400 and the inorganic substrate 300. As a result, peeling between the bonding part 400 and the inorganic substrate 300 can be prevented.

[0062] Second Embodiment 8 is an explanatory diagram showing an exploded configuration of an inorganic substrate 300A of an electrostatic chuck according to the second embodiment. The electrostatic chuck according to the second embodiment differs from the electrostatic chuck 10 according to the first embodiment in the configuration of the inorganic substrate 300A. In the embodiments described below, the same components as those in the electrostatic chuck 10 according to the first embodiment are denoted by the same reference numerals, and the preceding description will be referred to.

[0063] As shown in the figure, inorganic substrate 300A has a configuration in which two inorganic substrates are laminated. A first inorganic substrate 301A shown in the upper part of the figure has only first fiber portions 310 having a plurality of fibers 311 extending in a first direction as fibers, and a second inorganic substrate 302A shown in the lower part of the figure has only second fiber portions 320 having a plurality of fibers 321 extending in a second direction as fibers. That is, in inorganic substrate 300A of this embodiment, first fiber portions 310 and second fiber portions 320 extend in different directions but do not intersect.

[0064] Even in this way, the anisotropy of expansion and contraction of the inorganic substrate 300A due to temperature changes can be reduced, the bias of stress occurring in the inorganic substrate 300A can be suppressed, and breakage of the inorganic substrate 300A can be suppressed.

[0065] Third Embodiment 9 is an explanatory diagram conceptually illustrating the configuration of an inorganic substrate 300B of an electrostatic chuck according to a third embodiment. The electrostatic chuck according to the third embodiment differs from the electrostatic chuck 10 according to the first embodiment in the configuration of the inorganic substrate 300B. In the embodiments described below, the same components as those in the electrostatic chuck 10 according to the first embodiment are denoted by the same reference numerals, and the preceding description is referred to.

[0066] As shown in the figure, in inorganic substrate 300B, fibers 311, 321, 331, 341, 351, and 361 are uniformly arranged radially. That is, the angle between fiber 311 and fiber 331 is 30 degrees, and similarly, the angle between fiber 331 and fiber 341 and the angle between fiber 341 and fiber 321 are also 30 degrees. Furthermore, fibers 351, 361, and 371 are arranged circumferentially and have different diameters and are arranged at equal intervals. Furthermore, fibers 311, 321, 331, 341, 351, and 361 intersect with fibers 311, 321, 331, 341, 351, and 361, and fibers 351, 361, and 371 also intersect with fibers 351, 361, and 371. Note that circumferentially arranged fibers 351, 361, and 371 may be formed into a continuous spiral shape.

[0067] In this way, the anisotropy of expansion and contraction of the inorganic substrate 300B due to temperature changes can be further reduced, and the bias in stress occurring in the inorganic substrate 300B can be further suppressed, thereby further suppressing breakage of the inorganic substrate 300B.

[0068] <Fourth embodiment> 10 is an explanatory diagram schematically illustrating an XZ cross-sectional configuration of an electrostatic chuck 10C according to a fourth embodiment. The electrostatic chuck 10C according to the fourth embodiment differs from the electrostatic chuck 10 according to the first embodiment in that the diameters of an inorganic substrate 300C and a bonding portion 400C are smaller than those of the first embodiment, and that an outer peripheral protection member 900C is further provided. In the embodiments described below, the same components as those of the electrostatic chuck 10 according to the first embodiment are denoted by the same reference numerals, and the preceding description will be referred to.

[0069] The outer peripheral protection member 900C is a member that protects the outer periphery of the inorganic substrate 300C and the bonding portion 400C, and in this embodiment, an O-ring made of a highly plasma-resistant material is used, such as a fluorine-based rubber material.

[0070] According to the electrostatic chuck 10C of this embodiment, since it is equipped with an outer peripheral protection member 900C, it is possible to suppress the diffusion of particles from the ends of the inorganic substrate 300C and the bonding portion 400C due to plasma processing of the wafer W (target object) held by the electrostatic chuck 10C.

[0071] Fifth Embodiment 11 is an explanatory diagram schematically illustrating an XZ cross-sectional configuration of an electrostatic chuck 10D according to a fifth embodiment. The electrostatic chuck 10D according to the fifth embodiment includes an outer periphery protection member 900D instead of the outer periphery protection member 900C in the electrostatic chuck 10C according to the fourth embodiment.

[0072] The peripheral protective member 900D of this embodiment is formed in a substantially annular planar shape and has a thickness equal to the combined thickness of the inorganic substrate 300C and the bonding portion 400C. The peripheral protective member 900D may be formed on the outer peripheral surfaces of the inorganic substrate 300C and the bonding portion 400C, and a gap may be formed between the outer peripheral surfaces of the inorganic substrate 300C and the bonding portion 400C and the peripheral protective member 900D. In other embodiments, the peripheral protective member 900D may be formed on a portion of the outer peripheral surfaces of the inorganic substrate 300C and the bonding portion 400C. In this embodiment, the peripheral protective member 900D is primarily composed of alumina, a material with high plasma resistance. Alternatively, the peripheral protective member 900D may be formed using the same material as the plate-shaped portion 100. The peripheral protective member 900D can be formed by thermal spraying, cold spraying, aerosol deposition, or the like. It can also be formed by fitting a C-ring.

[0073] Even with this configuration, like the fourth embodiment, it is possible to suppress the diffusion of particles from the ends of the inorganic substrate 300C and the bonding portion 400C.

[0074] <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.

[0075] In the above embodiment, an example was shown in which the fibers contained in the inorganic substrate extended from end to end, but the fibers do not have to extend from end to end. For example, the fibers may be longer than the radius of the inorganic substrate. They may also be longer than one-third the length of the inorganic substrate. However, longer fibers are preferable because they can share stress by expanding and contracting the fibers themselves.

[0076] In the first embodiment, the first fiber portion 310 and the second fiber portion 320 are fiber bundles each made up of a plurality of fibers, but the first fiber portion and the second fiber portion may each contain at least one fiber. The fiber bundles may also be twisted.

[0077] In the first embodiment, a plain woven cloth-like fiber portion 330 is exemplified, but cloth-like fiber portions of other weaves such as twill and satin may also be used. Furthermore, cloth-like fiber portions knitted by plain knitting (jersey knitting), rib knitting (rib knitting), purl knitting, or the like may also be used. Furthermore, a portion of the fiber portion may be cloth-like. That is, the fiber portion may include a cloth-like portion in which fibers are woven or knitted. Furthermore, in addition to the first fiber portion 310 and the second fiber portion 320, fibers extending in other directions may also be woven or knitted.

[0078] In the fiber portion 330 in the inorganic substrate 300, if the number of fibers 311 contained in the first fiber portion 310 is different from the number of fibers 321 contained in the second fiber portion 320, anisotropy exists in the inorganic substrate. If the plate-like member 100 has in-plane anisotropy, the anisotropy is mutually cancelled out by the anisotropy of the inorganic substrate 100, and stress is cancelled out, thereby suppressing stress generation. As a result, peeling between the plate-like member 100 and the inorganic substrate 300 can be suppressed.

[0079] The fiber part 330 may be provided with undulations (concavities and depressions) in the Z-axis direction. By providing undulations, the inorganic substrate stretches by the amount of expansion and contraction of the undulations compared to a planar fiber part, and therefore peeling between the plate-like part 100 and the inorganic substrate 300 can be suppressed.

[0080] In the above embodiment, the inorganic binder portion contains inorganic particles having a thermal expansion coefficient smaller than that of the inorganic resin, but the inorganic binder portion does not necessarily have to contain inorganic particles.

[0081] The thermal expansion coefficients of the plate-like portion and the inorganic substrate may be the same, or the thermal expansion coefficient of the inorganic substrate may be smaller than that of the plate-like portion. Even in such cases, by employing the inorganic substrate of the above-described form, it is possible to prevent the inorganic substrate from breaking due to stress caused by a temperature gradient inside the inorganic substrate.

[0082] In the above embodiment, an example is shown in which an object is held on the first surface S1 of the plate-shaped portion 100, but it is also possible to bond another ceramic substrate onto the plate-shaped portion 100 and hold the object on top of that.

[0083] In the above embodiment, an electrostatic chuck is used as an example of the holding device, but the holding device is not limited to an electrostatic chuck. For example, the holding device may be configured as a heater device, susceptor, or mounting table for a vacuum device such as CVD, PVD, or PLD (Pulsed Laser Deposition).

[0084] In the above embodiment, the holding device is provided with a stack of plate-like members having a substantially circular planar shape, but the planar shape is not limited to the above embodiment. For example, the holding device may have a rectangular or polygonal planar shape.

[0085] The present disclosure is not limited to the above-described embodiments, examples, and modifications, and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0086] The present disclosure can also be realized as the following application examples. [Application example 1] A holding device for holding an object, a plate-shaped portion formed in a plate shape; a plate-like inorganic substrate having a fiber portion and an inorganic binder portion and a bonding surface to be bonded to the plate-like portion; a plate-shaped base portion disposed on the opposite side of the inorganic substrate from the plate-shaped portion; a bonding portion disposed between the inorganic substrate and the base portion and bonding the inorganic substrate and the base portion; Equipped with The inorganic binder portion is the inorganic binder is composed of an inorganic material as a main component and contains an inorganic resin that bonds to the plate-like portion, and is present at least partially between the plate-like portion and the fiber portion; The fiber portion is comprising a plurality of fibers formed of at least one of a metal and an inorganic material; a first fiber portion having one or more fibers extending in a first direction along the bonding surface; a second fiber portion having one or more fibers extending in a second direction that is different from the first direction and along the bonding surface; characterized in that it has holding device. [Application example 2] The holding device according to Application Example 1, The first fiber portion and the second fiber portion intersect with each other. holding device. [Application example 3] The holding device according to Application Example 1 or Application Example 2, The fiber portion is The first fiber part and the second fiber part are in the form of a cloth including a woven or knitted part. holding device. [Application example 4] The holding device according to any one of Application Examples 1 to 3, The fiber portion is disposed within the inorganic binder portion. holding device. [Application example 5] The holding device according to any one of Application Examples 1 to 4, The inorganic binder portion includes inorganic particles having a thermal expansion coefficient smaller than that of the inorganic resin. holding device. [Application Example 6] The holding device according to any one of Application Examples 1 to 5, The plate-like portion and the inorganic substrate have different thermal expansion coefficients. holding device. [Explanation of symbols]

[0087] 10, 10C, 10D...Electrostatic chuck 100...Plate-shaped part 103…zygote 130...Adsorption electrode 200...Base 210... refrigerant flow path 300, 300A, 300B, 300C, 300P1, 300P2...Inorganic substrate 301...Prepreg 301A...First inorganic substrate 302A…Second inorganic substrate 310...First fiber section 311, 312, 321, 331, 341, 351, 361, 371...Fiber 320...Second fiber section 330...Fiber section 340...Inorganic binder part 350...Inorganic particles 400…Joint part 401...First sheet adhesive 402...Second sheet adhesive 900C, 900D...Periphery protection member W...wafer C...crack S1...Side 1 S2…Joint surface

Claims

1. A holding device for holding an object, a plate-shaped portion formed in a plate shape; a plate-like inorganic substrate having a fiber portion and an inorganic binder portion and a bonding surface to be bonded to the plate-like portion; a plate-shaped base portion disposed on the opposite side of the inorganic substrate from the plate-shaped portion; a bonding portion disposed between the inorganic substrate and the base portion and bonding the inorganic substrate and the base portion; Equipped with The inorganic binder portion is the inorganic binder is composed of an inorganic material as a main component and contains an inorganic resin that bonds to the plate-like portion, and is present at least partially between the plate-like portion and the fiber portion; The fiber portion is comprising a plurality of fibers formed of at least one of a metal and an inorganic material; a first fiber portion having one or more fibers extending in a first direction along the bonding surface; a second fiber portion having one or more fibers extending in a second direction that is different from the first direction and along the bonding surface; characterized in that it has holding device.

2. A holding device as described in claim 1, The tensile strength of the fiber is greater than that of the inorganic binder portion. holding device.

3. A holding device as described in claim 1, The thermal conductivity of the inorganic material constituting the inorganic substrate is 1.8 W / mK or less. holding device.

4. 2. The holding device of claim 1, The first fiber portion and the second fiber portion intersect with each other. holding device.

5. 3. The holding device according to claim 2, The fiber portion is The first fiber part and the second fiber part are in the form of a cloth including a woven or knitted part. holding device.

6. 2. The holding device of claim 1, The fiber portion is disposed within the inorganic binder portion. holding device.

7. 2. The holding device of claim 1, The inorganic binder portion includes inorganic particles having a thermal expansion coefficient smaller than that of the inorganic resin. holding device.

8. A holding device according to any one of claims 1 to 7, The plate-like portion and the inorganic substrate have different thermal expansion coefficients. holding device.

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