Holding device and substrate unit

Abstract

To provide another technique of improving the cooling performance of a holding device for holding a target object.SOLUTION: A holding device includes: a holding unit formed in a plate and having a mount surface on which a target object is mounted; a base board unit arranged on the opposite side to the side where the mount surface is arranged across the holding unit; and a carbon nanotube layer arranged between the holding unit and the base board unit, in which a plurality of carbon nanotubes are arranged so that the longer direction of the carbon nanotubes are substantially along the direction of the lamination in which the holding unit and the base board unit are laminated. At least a part of the carbon nanotubes are tangled with one another.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] For example, an electrostatic chuck is used as a holding device for holding an object such as a wafer when manufacturing a semiconductor. The electrostatic chuck includes a holding part on which the object is placed, a base part that supports the holding part, and a joint part that joins the holding part and the base part. When the electrostatic chuck is used in an environment where it is exposed to strong plasma energy or in an environment where high power is input to the electrostatic chuck, the wafer placement surface is likely to become hot, and the temperature of the wafer increases, so it is required to efficiently transfer heat from the holding part to the base part.

[0003] To address this issue, a technique has been proposed in which carbon nanotubes (CNTs) are used as joints and the carbon nanotubes are oriented so that their longitudinal direction is aligned with the stacking direction of the holder and base (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-111688 A Summary of the Invention [Problem to be solved by the invention]

[0005] According to the technology described in Patent Document 1, by using CNTs, which have high thermal conductivity, between the holding part and the base and orienting the CNTs as described above, heat can be efficiently transferred from the holding part to the base.

[0006] However, even with the techniques described in the above patent documents, there are cases in which sufficient cooling performance cannot be obtained.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide another technique for improving cooling performance in a holding device that holds an object. [Means for solving the problem]

[0008] The present invention has been made to solve the above-mentioned problems, and can be realized in the following forms.

[0009] (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 holding section having a mounting surface on which the object is placed, a base section disposed on the opposite side of the holding section from the mounting surface, and a carbon nanotube layer disposed between the holding section and the base section, the carbon nanotubes being arranged such that their longitudinal directions are substantially aligned with a stacking direction of the holding section and the base section, and at least some of the carbon nanotubes are entangled with each other.

[0010] The thermal conductivity in the axial direction of the carbon nanotubes is very large compared to resin or a highly thermally conductive resin sheet that has been made highly thermally conductive by a filler. The holding device of this configuration includes a carbon nanotube layer between the holding part and the base part, in which a plurality of carbon nanotubes are arranged so that their longitudinal direction is substantially along the stacking direction of the holding part and the base part, and therefore it is possible to promote the transfer of heat from the holding part to the base part via the carbon nanotubes. Furthermore, at least a portion of the plurality of carbon nanotubes is entangled with each other, and the carbon nanotubes are in contact with each other. Therefore, even if the lengths of the plurality of carbon nanotubes vary, the orientation of the plurality of carbon nanotubes becomes random, so that the height as a whole can be averaged, and the thermal conductivity can be averaged. As a result, it is possible to improve the thermal conductivity compared to a case in which the plurality of carbon nanotubes are not entangled with each other.

[0011] Furthermore, by forming the carbon nanotubes in a structure in which at least a portion of them are entangled, the carbon nanotubes can flexibly move in the shear direction, and breakage of the carbon nanotube layer due to thermal stress can be suppressed.

[0012] (2) In the holding device of the above aspect, the plurality of carbon nanotubes may be in contact with the holding portion, which can further promote transfer of heat from the holding portion to the base portion.

[0013] (3) In the holding device of the above aspect, some of the carbon nanotubes may be unentangled with each other and oriented such that their longitudinal direction is aligned with the stacking direction of the holding part and the base part, thereby improving the thermal conductivity of the carbon nanotube layer.

[0014] (4) The holding device of the above embodiment may further include an adhesive layer that adheres the carbon nanotube layer to the base, and at least some of the carbon nanotubes may penetrate the adhesive layer and contact the base. When the carbon nanotube layer is formed on the holding part, the carbon nanotube layer may be adhered to the base via the adhesive layer, thereby joining the holding part and the base via the carbon nanotube layer. Furthermore, since at least some of the carbon nanotubes are in contact with both the holding part and the base, heat can be quickly dissipated from the holding part via the carbon nanotubes even if an adhesive layer with low thermal conductivity is present between the carbon nanotube layer and the base.

[0015] (5) The holding device of the above embodiment may further include a joining portion that mechanically joins the holding portion and the base portion. In this way, the holding portion and the base portion can be joined in a state in which the carbon nanotube layer is disposed between them without the need for an adhesive layer. Generally, adhesive layers are often made of a material with low thermal conductivity, such as resin, and therefore, by mechanically joining the holding portion and the base portion, thermal conductivity can be improved.

[0016] (6) According to another aspect of the present invention, there is provided a substrate unit comprising: a plate-shaped ceramic wiring board having a first surface and a second surface that is a reverse surface of the first surface, an electronic component mounted on the first surface side of the ceramic wiring board, a heat dissipation member disposed on the second surface side of the ceramic wiring board and dissipating heat from the electronic component, and a carbon nanotube layer disposed at least either between the ceramic wiring board and the heat dissipation member or between the ceramic wiring board and the electronic component, the carbon nanotube layer being formed by disposing a plurality of carbon nanotubes with their longitudinal direction substantially aligned with a lamination direction of the ceramic wiring board and the heat dissipation member, and at least some of the plurality of carbon nanotubes being entangled with each other.

[0017] According to this configuration, a carbon nanotube layer is disposed at least either between the ceramic wiring board and the heat dissipation member or between the ceramic wiring board and the electronic component, thereby improving the heat dissipation properties of the electronic component and the ceramic wiring board, as described above.

[0018] (7) According to another aspect of the present invention, there is provided a substrate unit comprising: a plate-shaped ceramic wiring board, an electronic component mounted on the ceramic wiring board, a heat dissipation member laminated on the electronic component and dissipating heat from the electronic component, and a carbon nanotube layer disposed at least either between the electronic component and the heat dissipation member or between the electronic component and the ceramic wiring board, the carbon nanotube layer being formed by disposing a plurality of carbon nanotubes with their longitudinal direction generally aligned with the lamination direction of the ceramic wiring board and the heat dissipation member, and at least some of the plurality of carbon nanotubes being entangled with each other.

[0019] According to this configuration, a carbon nanotube layer is disposed at least either between the electronic component and the heat dissipation member, or between the electronic component and the ceramic wiring board, thereby improving the heat dissipation properties of the electronic component and the ceramic wiring board, as described above.

[0020] 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, and the like. [Brief description of the drawings]

[0021] [Figure 1] 1 is a perspective view illustrating a schematic external configuration of an electrostatic chuck according to a first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram illustrating a schematic XZ cross-sectional configuration of the electrostatic chuck. [Diagram 3] 1A to 1C are explanatory diagrams conceptually showing a method for manufacturing an electrostatic chuck according to an embodiment of the present invention. [Figure 4] 2 is a SEM photograph of a carbon nanotube layer in an example. [Diagram 5] 1 is a SEM photograph of a carbon nanotube layer of a comparative example. [Figure 6] FIG. 11 is an explanatory view illustrating a schematic XZ cross-sectional configuration of an electrostatic chuck according to a second embodiment. [Figure 7] 13 is an explanatory diagram illustrating a schematic XZ cross-sectional configuration of a substrate unit according to a third embodiment. FIG. [Figure 8] 13 is an explanatory diagram illustrating a schematic XZ cross-sectional configuration of a substrate unit according to a fourth embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] First Embodiment FIG. 1 is a perspective view that shows a schematic external configuration of an electrostatic chuck 10 according to a first embodiment. FIG. 2 is an explanatory diagram that shows a schematic XZ cross-sectional configuration of the electrostatic chuck 10. In FIG. 1 and FIG. 2, mutually orthogonal X, Y and Z axes are shown to specify the directions. In FIG. 2, the positive Y direction is the direction toward the back side of the paper. In this specification, for convenience, the positive Z direction is referred to as the upward direction and the negative Z direction is referred to as the downward direction, but the electrostatic chuck 10 may actually be installed in a direction different from these directions.

[0023] 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 holding portion 100 arranged side by side in the vertical direction (Z-axis direction), a base portion 200, a carbon nanotube layer 300 arranged between the holding portion 100 and the base portion 200, and an adhesive layer 500 that bonds the carbon nanotube layer 300 and the base portion 200 together. The electrostatic chuck 10 in this embodiment is also referred to as a "holding device."

[0024] The holding part 100 is a plate-like member having a substantially circular, flat mounting surface S1, and is formed mainly from ceramic (e.g., alumina, aluminum nitride, etc.). In this specification, when a specific component is "the main component" or "the main material forming the specific component", it means that the content of the specific component is 50 volume % or more.

[0025] An adsorption electrode 400 (FIG. 2) made of a conductive material (e.g., tungsten or molybdenum) is disposed inside the holding part 100. The shape of the adsorption electrode 400 as viewed in the Z-axis direction is, for example, substantially circular. When a voltage is applied to the adsorption electrode 400 from a power source (not shown), an electrostatic attraction force is generated, and the wafer W is adsorbed and fixed to the mounting surface S1 of the holding part 100 by this electrostatic attraction force.

[0026] The base portion 200 is a substantially circular, flat, plate-like member having a larger diameter than the holding portion 100, and is disposed on the opposite side of the mounting surface S1 with respect to the holding portion 100. The base portion 200 is formed of a metal such as aluminum or an aluminum alloy.

[0027] A coolant flow passage 210 (FIG. 2) is formed inside the base portion 200. When the wafer W held by the holding portion 100 of the electrostatic chuck 10 is processed using plasma, heat is input from the plasma to the wafer W, and the temperature of the wafer W rises. When a coolant (e.g., a fluorine-based inert liquid or water) flows through the coolant flow passage 210 formed in the base portion 200, the base portion 200 is cooled, and the holding portion 100 is cooled by heat transfer between the base portion 200 and the holding portion 100 via the carbon nanotube layer 300, and the wafer W held on the mounting surface S1 of the holding portion 100 is cooled. This realizes temperature control of the wafer W.

[0028] The carbon nanotube layer 300 is a plate-like member having a substantially circular flat shape with a diameter equal to that of the holder 100, and is disposed between the holder 100 and the base 200. The carbon nanotube layer 300 has a first contact surface 351 (FIG. 2) on the holder 100 side and a second contact surface 352 (FIG. 2) on the base 200 side. The carbon nanotube layer 300 is made of carbon nanotubes and does not contain resin. As will be described in detail later, the carbon nanotube layer 300 is an aggregate of a plurality of carbon nanotubes C, and is disposed so that its longitudinal direction (fiber direction) is substantially along the stacking direction (Z-axis direction in the drawing) of the holder 100 and the base 200. Here, "substantially along" the stacking direction includes a state in which the carbon nanotubes C are bent as shown in the drawing, but extend from the holder 100 toward the base 200 as a whole. The entire surface of the first contact surface 351 of the carbon nanotube layer 300 is in contact with the holder 100.

[0029] 2, the X1 portion surrounded by a dashed line is conceptually illustrated in an enlarged scale. As illustrated, in the carbon nanotube layer 300, some of the carbon nanotubes C are entangled with each other, while the remaining portions are not entangled with each other and are oriented such that their longitudinal direction is along the stacking direction of the holding portion 100 and the base portion 200. That is, the carbon nanotube layer 300 has a first portion CG1 in which the carbon nanotubes C are entangled with each other, and a second portion CG2 in which the carbon nanotubes C are oriented such that their longitudinal direction is along the stacking direction of the holding portion 100 and the base portion 200.

[0030] Since the carbon nanotube C has high thermal conductivity in the growth direction (its longitudinal direction), it is preferable that the carbon nanotube C is oriented in the stacking direction with its longitudinal direction and that the carbon nanotube C is in contact with the holding part 100 and the base part 200, since high thermal conductivity can be obtained. However, when a plurality of carbon nanotubes C are grown, the lengths of the plurality of carbon nanotubes C differ from each other due to different growth rates. For example, in the case of a carbon nanotube layer in which a plurality of carbon nanotubes C with different lengths are oriented in the stacking direction, even if a long carbon nanotube C is in contact with both the holding part 100 and the base part 200 and high thermal conductivity is obtained, a short carbon nanotube C cannot be in contact with both, and high thermal conductivity cannot be obtained, so that the carbon nanotube layer as a whole does not have high thermal conductivity. In addition, if the short carbon nanotube C is in contact with both the holding part 100 and the base part 200, the long carbon nanotube C is deformed, and the carbon nanotube C becomes coarse and dense on the surface where the carbon nanotube layer contacts, and in-plane variation in thermal conductivity occurs. Furthermore, variations in density of the carbon nanotubes C cause cracks in the carbon nanotube layer, and the cracks cannot be repaired, thus impeding the cooling performance.

[0031] In contrast, in the first portion CG1 of the carbon nanotube layer 300 of this embodiment, multiple carbon nanotubes C of different lengths are entangled with random orientations. By contacting the multiple carbon nanotubes C with each other, the thermal conductivity can be averaged, and therefore the first portion CG1 can have improved thermal conductivity compared to a case in which multiple carbon nanotubes C of different lengths are oriented in the stacking direction.

[0032] Furthermore, since the first portion CG1 of the carbon nanotube layer 300 is made up of multiple carbon nanotubes C entangled with one another, even if the first portion CG1 is pressed in the stacking direction (Z-axis direction), local deformation and unevenness in density can be suppressed.

[0033] Furthermore, when a temperature change in the electrostatic chuck 10 causes thermal stress in the shear direction to act on the carbon nanotube layer 300 due to the difference in thermal expansion coefficient between the holding portion 100 and the base portion 200, the multiple carbon nanotubes C in the first portion CG1 of the carbon nanotube layer 300 are entangled with each other and can move flexibly in the shear direction, thereby preventing breakage of the carbon nanotube layer 300.

[0034] Furthermore, the carbon nanotube layer 300 has a second portion CG2 in which the longitudinal direction of the multiple carbon nanotubes C is oriented along the stacking direction of the holding portion 100 and the base portion 200. As described above, the carbon nanotubes C can obtain high thermal conductivity when their longitudinal direction is oriented in the stacking direction, and therefore the carbon nanotube layer 300 of this embodiment can improve thermal conductivity compared to the case without the second portion CG2.

[0035] The state of the carbon nanotubes C can be confirmed by the following method. The holding part 100 and the base part 200 on which the carbon nanotubes C are formed are cut and the cross section is observed with a scanning electron microscope (SEM) or the like, whereby the state of the carbon nanotubes C can be confirmed. Among electron microscopes, a field emission scanning electron microscope (FE-SEM) is preferred because it is highly versatile and allows observation at relatively high magnification. The magnification can be set appropriately so that the overall orientation direction and the shape of each individual nanotube can be confirmed.

[0036] 2, some of the carbon nanotubes C penetrate the adhesive layer 500 and contact the base part 200. Since the carbon nanotubes C contact both the holding part 100 and the base part 200, even if the adhesive layer 500, which has low thermal conductivity, is present between the carbon nanotube layer 300 and the base part 200, the heat of the holding part 100 can be dissipated quickly via the carbon nanotubes C.

[0037] The thermal conductivity of the carbon nanotubes C is, for example, about 3000 W / mK to 6000 W / mK in the axial direction of the carbon nanotubes C. For example, even when a filler is added to a resin adhesive to increase thermal conductivity, the thermal conductivity is about 10 W / mK, and the thermal conductivity of the carbon nanotubes C is incomparably greater than this. Therefore, by disposing the carbon nanotube layer 300 made of the carbon nanotubes C between the holding part 100 and the base part 200, the electrostatic chuck 10 of this embodiment can achieve rapid heating and cooling.

[0038] The thermal decomposition temperature of the carbon nanotubes C is about 500° C. to 600° C. in the atmosphere, which is higher than the thermal decomposition temperature of normal resins, and the carbon nanotubes C have excellent heat resistance, so that the heat resistance of the electrostatic chuck 10 can be improved.

[0039] The diameter of the carbon nanotube C is not particularly limited, but is preferably about 10 nm to several tens of nm. The diameter of the carbon nanotube C is preferably on the thin side, that is, the layer structure of the carbon nanotube C is preferably close to a single layer. This is because the thinner the carbon nanotube C, the easier it is to bend and the easier it is to deform in the shear direction according to the difference in thermal expansion coefficient.

[0040] The carbon nanotubes C may be either single-walled or multi-walled carbon nanotubes. The surface density of the carbon nanotubes C is not particularly limited, but is preferably 5×10 9 book / cm 2 The above is preferred.

[0041] The adhesive layer 500 is disposed between the carbon nanotube layer 300 and the base portion 200, and bonds the carbon nanotube layer 300 to the base portion 200. The adhesive layer 500 of the present embodiment contains an adhesive formed of a resin material and an inorganic filler.

[0042] For example, silicone resin, epoxy resin, fluororesin, acrylic resin, etc. can be used as the adhesive contained in the adhesive layer 500. Silicone resin is preferable because it has relatively excellent heat resistance and flexibility.

[0043] As the inorganic filler, granular or powdery substances made of various inorganic materials including ceramics, metal oxides, metals, or other inorganic compounds can be used. Specifically, as the inorganic filler, for example, aluminum nitride (AlN), aluminum oxide (alumina: Al2O3), boron nitride (BN), zirconium oxide (zirconia: ZrO2), yttrium oxide (yttria: Y2O3), yttrium fluoride (YF3), silicon carbide (SiC), silicon nitride (Si3N4), silicon dioxide (silica: SiO2), iron oxide, barium sulfate, calcium carbonate, etc. can be used. The inorganic materials constituting the inorganic filler as described above generally have a higher thermal conductivity than the resin that is the adhesive, so that the thermal conductivity of the adhesive layer 500 can be increased by adding the inorganic filler to the adhesive. In particular, from the viewpoint of having a relatively high thermal conductivity and making it easier to suppress the thermal resistance of adhesive layer 500, aluminum nitride, aluminum oxide, and silicon carbide are preferable as materials constituting the inorganic filler, and aluminum nitride and aluminum oxide are particularly preferable.

[0044] 3 is an explanatory diagram conceptually showing a method for manufacturing the electrostatic chuck 10 of this embodiment. A holder 100 is prepared (FIG. 3(A)), and a catalytic metal film 301 is formed on the surface of the holder 100 (FIG. 3(B)). A carbon source is supplied to the catalytic metal film 301 formed on the holder 100, and carbon nanotubes C are grown to form a carbon nanotube layer 300 (FIG. 3(C)). By preparing a holder 100 having a certain degree of roughness on its surface, the carbon nanotubes C can be grown in random directions and can be grown so as to be entangled with each other. Meanwhile, a base 200 is prepared (FIG. 3(D)), and an adhesive layer 500 is formed on the surface of the base 200 (FIG. 3(E)).

[0045] By placing the holding portion 100 facing the base portion 200 so that the second contact surface 352 of the carbon nanotube layer 300 faces the adhesive layer 500 and pressing them together, the adhesive layer 500 and the carbon nanotube layer 300 are adhered to each other, the holding portion 100 and the base portion 200 are joined, and the electrostatic chuck 10 is completed.

[0046] An example of the formation of the above-mentioned carbon nanotube layer 300 (FIGS. 3(B) and 3(C)) will be described below. 3B, a catalytic metal film 301 is formed on the holder 100 by, for example, a sputtering method, a chemical vapor deposition (CVD) method, a physical vapor deposition (PVD) method, a vacuum deposition method, or the like. An example of the catalytic metal film 301 is an Fe (iron) film with a thickness of about 2.5 nm. As the catalytic metal, in addition to Fe, Co (cobalt), Ni (nickel), W (tungsten), Mo (molybdenum), Au (gold), Ag (silver), Pt (platinum), or an alloy containing at least one of these materials may be used. In addition, as the undercoat film of these catalytic metals, a film made of W (tungsten), Mo (molybdenum), Ti (titanium), Zr (zirconium), V (vanadium), Cr (chromium), Al (aluminum), Cu (copper), Au (gold), Pt (platinum), Pd (palladium), Al2O3 (aluminum oxide), TiO2 (titanium oxide), or a film made of an alloy containing at least one of these materials may be formed. For example, a laminated structure of Fe (about 2.5 nm) / Al (about 10 nm) can be applied. As a method for forming the undercoat layer, in addition to the same method as the ceramic wiring formation method (printing and simultaneous firing of paste containing metal components), sputtering, CVD, PVD, vacuum deposition, etc. can be mentioned.

[0047] In FIG. 3(C), carbon nanotubes are grown on the holder 100 by, for example, hot filament CVD using a catalytic metal film 301 as a catalyst. The carbon nanotube growth conditions are, for example, a mixture gas of acetylene and argon (partial pressure ratio 1:9) as a raw material gas, a total gas pressure in the deposition chamber of about 1 kPa, a hot filament temperature of about 1000° C., and a growth time of about 20 minutes. Note that carbon nanotubes may be formed by other deposition methods such as thermal CVD and remote plasma CVD. The grown carbon nanotubes may be single-walled or multi-walled carbon nanotubes. In addition, as the carbon raw material, hydrocarbons such as methane and ethylene, and alcohols such as ethanol and methanol may be used in addition to acetylene. In this manner, carbon nanotube layer 300, which is an aggregate of a plurality of carbon nanotubes extending approximately along the normal direction of holding unit 100 (the stacking direction of holding unit 100 and base unit 200), can be formed on holding unit 100 in the region where catalyst metal film 301 is formed. In carbon nanotube layer 300 in this embodiment, a portion of the plurality of carbon nanotubes are entangled with one another and a portion are not entangled with one another, and the longitudinal direction of the carbon nanotubes is oriented along the stacking direction of holding unit 100 and base unit 200.

[0048] According to this manufacturing method, the carbon nanotubes C use the holding part 100 as a substrate, and the carbon nanotubes C are grown on the surface of the holding part 100. Therefore, there is no need to use adhesive on the holding part 100 side of the carbon nanotube layer 300, and the carbon nanotubes C and the holding part 100 are in good contact with each other, which can reduce the thermal resistance. EXAMPLES

[0049] The carbon nanotube layer 300 of this embodiment will be described below using examples. Fig. 4 is an SEM photograph of carbon nanotube layer 300 of an embodiment. Fig. 5 is an SEM photograph of carbon nanotube layer 300P of a comparative example. Figs. 4 and 5(A) are photographs of the substrate on which the carbon nanotube layer is formed, Figs. 4 and 5(B) are photographs (20x) of the carbon nanotube layer in plan view, Fig. 4(C) is a photograph (5000x) of the carbon nanotube layer in plan view, and Fig. 5(C) is an enlarged photograph (5000x) of part X2 in Fig. 5(B). Part X2 shown in Fig. 5(B) is the part where carbon nanotube layer 300 has been turned over and the side is visible. <Manufacturing method> Metal nanoparticles were applied as a catalyst onto a substrate, and carbon source gas was blown into a heating furnace together with a carrier gas to synthesize carbon nanotubes (chemical vapor deposition (CVD) method). Iron was used as the catalyst, which is known to have the ability to decompose hydrocarbons and alcohols, which are the main carbon raw materials. The carbon nanotube layer of the example was formed under the same conditions as those used in the comparative example to grow carbon nanotubes of about 1 mm. The following was used as the substrate. Example Substrate material: Alumina (Al2O3) Surface treatment: After the surface was scraped to make it flat, it was polished on both sides with #230 and then cleaned. There is no distinction between the front and back. Size: 20mm x 20mm x 2mm (thickness) Comparison example: Substrate material: Quartz Surface processing: A double-sided polished quartz wafer for research use was cut to a specified size and cleaned, after which it was used as is without any surface processing.

[0050] As shown in Fig. 4(B), the surface of the carbon nanotube layer (Example) formed on the alumina substrate was uneven along the polishing lines on the surface of the alumina substrate. As shown in Fig. 4(C), in the carbon nanotube layer of the Example, the carbon nanotubes were not straight, but were tangled together to form a hairball shape.

[0051] As shown in FIG. 5(C), in the carbon nanotube layer of the comparative example, a plurality of carbon nanotubes were aligned substantially straight in a direction perpendicular to the substrate.

[0052] <Thermal cycle test> A carbon nanotube layer with a thickness of 1 mm was formed on an alumina ceramic plate with a diameter of 300 mm and a thickness of 5 mm. It was confirmed that the carbon nanotubes were in contact with each other by observing a similar sample prepared separately with an electron microscope. The carbon nanotubes formed on the alumina ceramic plate were bonded to an aluminum plate with a diameter of 300 mm and a thickness of 20 mm with a silicone adhesive with a thickness of 0.1 mm. Thereafter, a thermal cycle test was performed in which room temperature and 150°C were repeated, and it was confirmed by X-ray CT that there was no change before and after the test, and it was confirmed that no peeling occurred at the ends of the carbon nanotube layer. In other words, even if thermal stress in the shear direction acts on the carbon nanotube layer 300 due to the difference in thermal expansion coefficient between the alumina ceramic plate and the aluminum plate with temperature change, it can be said that the breakage of the carbon nanotube layer was suppressed because the multiple carbon nanotubes C are entangled with each other and can move flexibly in the shear direction.

[0053] As described above, according to the electrostatic chuck 10 of the present embodiment, the carbon nanotube layer 300, which does not contain resin and is formed by arranging a plurality of carbon nanotubes so that their longitudinal direction is substantially along the stacking direction of the holding part and the base part, is arranged between the holding part 100 and the base part 200, and therefore, it is possible to promote the transfer of heat from the holding part to the base part via the carbon nanotubes. In the carbon nanotube layer 300, some of the plurality of carbon nanotubes are entangled with each other, and the carbon nanotubes are in contact with each other. Therefore, even if the lengths of the plurality of carbon nanotubes vary, the orientation of the plurality of carbon nanotubes becomes random, so that the height as a whole can be averaged, and the thermal conductivity can be averaged. As a result, the thermal conductivity can be improved compared to a case where the plurality of carbon nanotubes do not have a portion where they are entangled with each other. That is, according to the electrostatic chuck 10 of the present embodiment, rapid heating and cooling can be realized.

[0054] In addition, by forming the carbon nanotubes into a structure in which some of the carbon nanotubes are entangled, the carbon nanotube layer can move flexibly in the shear direction without cracking. This makes it possible to suppress breakage of the carbon nanotube layer 300 due to thermal stress in the shear direction caused by the difference in thermal expansion coefficient between the holding part 100 and the base part 200 due to a temperature change of the electrostatic chuck 10.

[0055] Furthermore, the multiple carbon nanotubes are in contact with the holding part 100 since they grow from the holding part 100, and at least a portion of the multiple carbon nanotubes penetrates the adhesive layer 500 and contacts the base part 200. Therefore, the thermal conductivity between the holding part 100 and the base part 200 can be improved.

[0056] <Second embodiment> 6 is an explanatory diagram illustrating a schematic XZ cross-sectional configuration of an electrostatic chuck 10A according to a second embodiment. The electrostatic chuck 10A according to this embodiment includes a bonding portion 600 instead of the adhesive layer 500 in the electrostatic chuck 10 according to the first embodiment. In the following embodiments, 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.

[0057] The joint 600 mechanically joins the holder 100A and the base 200A together. In the example shown in Fig. 6, the joint 600 is a screw. In other examples, the joint 600 may be a clamp or the like.

[0058] The holding part 100A has a flange part 110 that protrudes in the XY plane direction. A female thread that screws into the male thread of the joint part 600 is formed on the flange part 110. A female thread that screws into the male thread of the joint part 600 is also formed on the base part 200A.

[0059] In the electrostatic chuck 10A of this embodiment, a holding portion 100A and a base portion 200A are joined by a joint 600 with a carbon nanotube layer 300 interposed therebetween, as shown in the drawing.

[0060] According to this embodiment 10A, since no adhesive layer 500 is provided between the carbon nanotube layer 300 and the base portion 200A, the carbon nanotube layer 300 and the base portion 200A are easily in direct contact with each other, and the thermal conductivity between the holding portion 100A and the base portion 200A can be improved more than that of the electrostatic chuck 10 of the first embodiment.

[0061] <Third embodiment> 7 is an explanatory diagram that shows a schematic XZ cross-sectional configuration of the substrate unit 1 of the third embodiment. The substrate unit 1 includes a plate-shaped ceramic wiring substrate 20 having a first surface 21 and a second surface 22 that is the reverse side of the first surface 21, an electronic component 30 such as a semiconductor device mounted on the first surface 21 side of the ceramic wiring substrate 20, a heat dissipation member 40 that is disposed on the second surface 22 of the ceramic wiring substrate 20 and dissipates heat from the electronic component 30, a first carbon nanotube layer 310 that is disposed between the ceramic wiring substrate 20 and the electronic component 30, and a second carbon nanotube layer 320 that is disposed between the ceramic wiring substrate 20 and the heat dissipation member 40. The first carbon nanotube layer 310 and the second carbon nanotube layer 320 have the same configuration as the carbon nanotube layer 300 of the first embodiment. That is, a part of the multiple carbon nanotubes of the first carbon nanotube layer 310 and the second carbon nanotube layer 320 are entangled with each other. The first carbon nanotube layer 310 and the second carbon nanotube layer 320 of this embodiment are also simply referred to as "carbon nanotube layers."

[0062] According to the substrate unit 1 of the present embodiment, the first carbon nanotube layer 310 is provided between the electronic component 30 and the ceramic wiring board 20, and the second carbon nanotube layer 320 is provided between the ceramic wiring board 20 and the heat dissipation member 40, so that the heat of the heat-generating electronic component 30 can be transferred to the heat dissipation member 40 via the first carbon nanotube layer 310 and the second carbon nanotube layer 320. Therefore, overheating of the electronic component 30 can be suppressed.

[0063] <Fourth embodiment> FIG. 8 is an explanatory diagram that shows a schematic XZ cross-sectional configuration of the substrate unit 1A of the fourth embodiment. The substrate unit 1 includes a ceramic wiring substrate 20, an electronic component 30 mounted on the ceramic wiring substrate 20, a heat dissipation member 40 that is laminated on the electronic component 30 and dissipates heat from the electronic component 30, a first carbon nanotube layer 310 disposed between the ceramic wiring substrate 20 and the electronic component 30, and a third carbon nanotube layer 330 disposed between the electronic component 30 and the heat dissipation member 40. The first carbon nanotube layer 310 and the third carbon nanotube layer 330 have the same configuration as the carbon nanotube layer 300 of the first embodiment. That is, some of the multiple carbon nanotubes of the first carbon nanotube layer 310 and the third carbon nanotube layer 330 are intertwined with each other. The first carbon nanotube layer 310 and the third carbon nanotube layer 330 of this embodiment are also simply called "carbon nanotube layers".

[0064] According to the substrate unit 1A of the present embodiment, the first carbon nanotube layer 310 is provided between the electronic component 30 and the ceramic wiring substrate 20, and the third carbon nanotube layer 330 is provided between the electronic component 30 and the heat dissipation member 40, so that the heat of the heat-generating electronic component 30 can be transferred to the ceramic wiring substrate 20 and the heat dissipation member 40 via the first carbon nanotube layer 310 and the third carbon nanotube layer 330, respectively. As a result, overheating of the electronic component 30 can be suppressed.

[0065] <Modifications 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 and scope of the invention. For example, the following modifications are also possible.

[0066] In the first embodiment, the carbon nanotube layer 300 has the first portion CG1 and the second portion CG2, but the carbon nanotube layer 300 does not have to have the second portion CG2. That is, the carbon nanotubes C constituting the carbon nanotube layer 300 may be entangled with each other over the entirety. Even in this case, the thermal conductivity can be improved and cracks in the carbon nanotube layer 300 can be suppressed.

[0067] In the above first embodiment, an example has been shown in which the carbon nanotube layer 300 is in contact with the holding part 100, but the carbon nanotube layer 300 does not have to be in contact with the holding part 100. For example, the carbon nanotubes C may be grown from the base part 200 to form a carbon nanotube layer, which may then be bonded to the holding part 100 via an adhesive layer. Furthermore, the carbon nanotube layer may be bonded to the holding part 100 via an adhesive layer and also to the base part 200 via an adhesive layer.

[0068] In the above first embodiment, an example has been described in which the electrostatic chuck 10 includes the adhesive layer 500, but the electrostatic chuck 10 does not necessarily need to include the adhesive layer 500. For example, if the carbon nanotube layer has adhesive properties, the holding part 100 and the base part 200 can be joined together via the carbon nanotube layer without including an adhesive layer.

[0069] In the above first embodiment, an example has been shown in which a portion of the carbon nanotube C penetrates the adhesive layer 500 and contacts the base portion 200, but the entire carbon nanotube C may penetrate the adhesive layer 500. Also, the entire carbon nanotube C may not penetrate the adhesive layer 500.

[0070] In the above third embodiment, an example was shown in which a carbon nanotube layer was disposed both between the ceramic wiring substrate 20 and the heat dissipation member 40 and between the ceramic wiring substrate 20 and the electronic component 30, but the carbon nanotube layer may be disposed in only one of the two positions.

[0071] In the above fourth embodiment, an example was shown in which a carbon nanotube layer was disposed both between the electronic component 30 and the heat dissipation member 40 and between the electronic component 30 and the ceramic wiring substrate 20, but it may be disposed in only one of them.

[0072] The materials of each part and each layer constituting the electrostatic chuck are not limited to those in the above embodiment. For example, the holding part 100 may be made of an insulating material other than ceramic. For example, a highly heat-resistant resin or a highly heat-resistant glass may be used. Examples of the highly heat-resistant resin include polyimide and polybenzimidazole. The base part 200 may be made of a material having high thermal conductivity other than metal. For example, ceramics such as alumina and aluminum nitride may be used.

[0073] 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).

[0074] In the above embodiment, the holding portion is a plate-shaped member having a substantially circular plane, but the planar shape of the holding portion is not limited to the above embodiment. For example, the holding portion may be a plate-shaped member having a rectangular plane, a polygonal plane, or the like.

[0075] The present invention has been described above based on the embodiments and modifications, but the above-mentioned embodiments are intended to facilitate understanding of the present invention and do not limit the present invention. The present invention may be modified or improved without departing from the spirit and scope of the claims, and the present invention includes equivalents thereof. Furthermore, if a technical feature is not described as essential in this specification, it may be deleted as appropriate.

[0076] The present invention can also be realized as the following application examples. [Application example 1] A holding device for holding an object, A holding portion formed in a plate shape and having a placement surface on which the object is placed; a base portion disposed on an opposite side of the placement surface with respect to the holding portion; a carbon nanotube layer disposed between the holding portion and the base portion, the carbon nanotubes being arranged such that their longitudinal direction is substantially aligned with a stacking direction of the holding portion and the base portion; Equipped with At least some of the carbon nanotubes are entangled with each other. holding device. [Application example 2] The holding device according to Application Example 1, The carbon nanotubes are in contact with the holding portion. holding device. [Application example 3] The holding device according to Application Example 1 or Application Example 2, A part of the plurality of carbon nanotubes is not entangled with each other, and is oriented so that its longitudinal direction is along the stacking direction of the holding part and the base part. holding device. [Application example 4] The holding device according to any one of Application Examples 1 to 3, moreover, an adhesive layer that adheres the carbon nanotube layer to the base portion; At least a portion of the carbon nanotubes penetrates the adhesive layer and contacts the base portion. holding device. [Application example 5] The holding device according to at least one of Application Examples 1 to 4, moreover, The present invention is characterized in that it includes a joint portion that mechanically joins the holding portion and the base portion. holding device. [Application Example 6] A substrate unit, a plate-shaped ceramic wiring substrate having a first surface and a second surface that is a reverse surface of the first surface; an electronic component mounted on the first surface side of the ceramic wiring substrate; a heat dissipation member disposed on the second surface side of the ceramic wiring board and configured to dissipate heat from the electronic components; a carbon nanotube layer disposed between the ceramic wiring board and the heat dissipation member and / or between the ceramic wiring board and the electronic component, the carbon nanotubes being arranged such that the longitudinal direction of each carbon nanotube is substantially aligned with the lamination direction of the ceramic wiring board and the heat dissipation member; Equipped with At least some of the carbon nanotubes are entangled with each other. Board unit. [Application Example 7] A substrate unit, A plate-shaped ceramic wiring board; an electronic component mounted on the ceramic wiring substrate; a heat dissipation member that is laminated on the electronic component and dissipates heat from the electronic component; a carbon nanotube layer disposed between the electronic component and the heat dissipation member or between the electronic component and the ceramic wiring board, the carbon nanotube layer being configured such that the longitudinal direction of the carbon nanotubes is substantially aligned with the lamination direction of the ceramic wiring board and the heat dissipation member; Equipped with At least some of the carbon nanotubes are entangled with each other. Board unit. [Explanation of symbols]

[0077] 1, 1A... Board unit 10, 10A...Electrostatic chuck 20...Ceramic wiring board 21...Side 1 22…Second side 30...Electronic components 40...Heat dissipation member 100, 100A…Holding part 110…Flange 200, 200A...Base part 210... Coolant flow path 300, 300P…Carbon nanotube layer 310…first carbon nanotube layer 320…Second carbon nanotube layer 330…Third carbon nanotube layer 351...1st contact surface 352…Second contact surface 400...Adsorption electrode 500...Adhesive layer 600…Joint part C…Carbon nanotube CG1...first part CG2…Second part S1: Placement surface W…wafer

Claims

1. A holding device for holding an object, A holding portion formed in a plate shape and having a placement surface on which the object is placed; a base portion disposed on an opposite side of the placement surface with respect to the holding portion; a carbon nanotube layer disposed between the holding portion and the base portion, the carbon nanotubes being arranged such that their longitudinal direction is substantially aligned with a stacking direction of the holding portion and the base portion; Equipped with At least some of the carbon nanotubes are entangled with each other. holding device.

2. 2. The holding device according to claim 1, The carbon nanotubes are in contact with the holding portion. holding device.

3. 2. The holding device according to claim 1, A part of the plurality of carbon nanotubes is not entangled with each other, and is oriented so that its longitudinal direction is along the stacking direction of the holding part and the base part. holding device.

4. 2. The holding device according to claim 1, moreover, an adhesive layer that adheres the carbon nanotube layer to the base portion; At least a portion of the carbon nanotubes penetrates the adhesive layer and contacts the base portion. holding device.

5. A holding device according to at least one of claims 1 to 4, moreover, The present invention is characterized in that it includes a joint portion that mechanically joins the holding portion and the base portion. holding device.

6. A substrate unit, a plate-shaped ceramic wiring substrate having a first surface and a second surface that is a reverse surface of the first surface; an electronic component mounted on the first surface side of the ceramic wiring substrate; a heat dissipation member disposed on the second surface side of the ceramic wiring board and configured to dissipate heat from the electronic components; a carbon nanotube layer disposed between the ceramic wiring board and the heat dissipation member and / or between the ceramic wiring board and the electronic component, the carbon nanotubes being arranged such that the longitudinal direction of each carbon nanotube is substantially aligned with the lamination direction of the ceramic wiring board and the heat dissipation member; Equipped with At least some of the carbon nanotubes are entangled with each other. Board unit.

7. A substrate unit, A plate-shaped ceramic wiring board; an electronic component mounted on the ceramic wiring substrate; a heat dissipation member that is laminated on the electronic component and dissipates heat from the electronic component; a carbon nanotube layer disposed between the electronic component and the heat dissipation member or between the electronic component and the ceramic wiring board, the carbon nanotube layer being configured such that the longitudinal direction of the carbon nanotubes is substantially aligned with the lamination direction of the ceramic wiring board and the heat dissipation member; Equipped with At least some of the carbon nanotubes are entangled with each other. Board unit.

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