Vacuum chuck and method for producing same

Abstract

A vacuum chuck according to the present disclosure comprises: a ceramic porous body which is in the form of a plate that has a first surface on the stage surface side, while having pores that are in communication with each other in the thickness direction; a support part which has an annular second surface that is positioned so as to surround the first surface; a first film which has air permeability and semiconductivity; and a second film which has a lower resistance than the first film. At least one of the support part and the second film does not have air permeability. The first film covers the first surface and the second surface. The second film covers at least the lateral surface of the support part and a part of the first film positioned on the second surface.

Description

Vacuum chuck and method of manufacturing same

[0001] The present disclosure relates to a vacuum chuck and a method for manufacturing the same.

[0002] Conventionally, adsorption members, such as those described in Patent Document 1, have been used as devices for fixing adsorbed objects such as semiconductor wafers. The adsorption member described in Patent Document 1 includes an adsorbent and a support for supporting the adsorbent. The adsorbent includes a porous ceramic substrate and a semiconductive first coating film located on the surface of the substrate facing the adsorbed object. Patent Document 1 further discloses that the surface of the support may include a second coating film connected to the first coating film and made of the same material as the first coating film, and that the second coating film may cover the upper surface, outer surface, and lower surface of the support. This configuration allows generated static electricity to be removed at an appropriate speed.

[0003] Japanese Patent Application Laid-Open No. 2018-200972

[0004] The vacuum chuck according to the present disclosure includes a plate-shaped ceramic porous body having a first surface on the mounting surface side and pores communicating in the thickness direction, a support portion having an annular second surface positioned so as to surround the first surface, a first film that is air-permeable and semi-conductive, and a second film that has lower resistance than the first film. At least one of the support portion and the second film is not air-permeable. The first film covers the first surface and the second surface. The second film covers at least the side surfaces of the first film and the support portion positioned on the second surface.

[0005] A method for manufacturing a vacuum chuck according to the present disclosure includes the steps of: preparing a porous ceramic body having an upper surface, a lower surface, and a side surface, and having pores communicating in a thickness direction; forming a first surface on the upper surface of the porous ceramic body and a ring-shaped second surface located on the peripheral portion of the upper surface so as to surround the first surface; coating the first surface and the second surface with a first film that is permeable and semi-conductive; coating at least the first film located on the second surface and the side surface of the porous ceramic body with a second film that has a lower resistance than the first film and is not permeable; and simultaneously grinding the first film and the second film so that the first film and the second film are substantially flush with each other.

[0006] Another method for manufacturing a vacuum chuck according to the present disclosure includes the steps of: preparing a plate-shaped porous ceramic body having pores communicating in the thickness direction; and a dense ceramic body having a recess for accommodating the porous ceramic body; joining the porous ceramic body to the recess and processing the porous ceramic body so that the porous ceramic body and the dense ceramic body are substantially flush with each other to form a first surface on the upper surface of the porous ceramic body; forming on the dense ceramic body a third surface that surrounds the recess, connects to a wall surface of the recess, and is substantially flush with the first surface; and forming on the dense ceramic body a second surface that surrounds the third surface and is located on the outer periphery of the third surface; coating from the first surface to the second surface with a first film that is air-permeable and semi-conductive; coating at least the first film and the side surface of the dense ceramic body that are located on the second surface with a second film that has a lower resistance than the first film; and simultaneously grinding the first film and the second film to make the first film and the second film substantially flush with each other.

[0007] Fig. 3 is a cross-sectional view showing a vacuum chuck according to an embodiment of the present disclosure; Fig. 4 is an enlarged explanatory view for explaining a modified example of region X shown in Fig. 1; Fig. 5 is a cross-sectional view showing a vacuum chuck according to another embodiment of the present disclosure; Fig. 6 is an enlarged explanatory view for explaining a modified example of region Y shown in Fig. 3; Fig. 7 is a perspective view of the vacuum chuck shown in Fig. 1;

[0008] In recent years, there has been a demand for chucking members that can more efficiently remove generated static electricity. To prevent sparks due to sudden discharge upon contact with a target object, the coating must be semiconductive. However, increasing the resistivity of the coating makes the coating more likely to become charged, while decreasing the resistivity of the coating makes it more likely to generate sparks. Therefore, there is a demand for a vacuum chuck that can efficiently remove generated static electricity and reduce the generation of sparks.

[0009] The vacuum chuck according to the present disclosure has a configuration as described in the section on means for solving the above problems, thereby efficiently removing static electricity that is generated and reducing the occurrence of sparks. Furthermore, the method for manufacturing a vacuum chuck according to the present disclosure can provide a vacuum chuck that efficiently removes static electricity that is generated and reduces the occurrence of sparks.

[0010] As described above, the vacuum chuck according to the present disclosure includes a ceramic porous body, a support portion, a first film, and a second film. The vacuum chuck according to the present disclosure will be described with reference to FIGS.

[0011] As shown in Fig. 1, a vacuum chuck 10 according to an embodiment of the present disclosure has a structure in which a porous one-piece molded body 3, in which a ceramic porous body 1 and a support portion 2 are integrated, is placed in contact with a substrate 4. Fig. 1 is a cross-sectional view showing the vacuum chuck 10 according to an embodiment of the present disclosure. The appearance of the vacuum chuck 10 is shown in Fig. 5. Fig. 5 is a perspective view of the vacuum chuck 10 according to an embodiment of the present disclosure.

[0012] The porous ceramic body 1 is plate-shaped and has a first surface 1a, which is the mounting surface side, and is not limited as long as it is made of porous ceramic. Examples of ceramics that form the porous ceramic body 1 include ceramics containing oxides such as aluminum oxide (alumina), titanium oxide, and zinc oxide, carbides such as silicon carbide, and nitrides such as silicon nitride, boron nitride, and aluminum nitride. "Porous" generally means having a certain number of pores within an object. However, in this specification, "porous" means having pores to the extent that the pores are interconnected and breathable.

[0013] In other words, a "porous body" is an object that has interconnected pores and is air-permeable. Air-permeable generally means that it has the property of being able to pass gas through. However, in this specification, "air-permeable" means that the porous body has enough air permeability to adsorb and hold an object such as a substrate on the surface when the back surface is suctioned with a vacuum pump. When the underside is connected to a suction tube to a vacuum pump and suctioned, the pressure difference (pressure loss) between the atmospheric pressure in the suction tube and the air pressure inside the suction tube may be 90 kPa or less. An object that does not have interconnected pores and is airtight is called a dense body. A dense body can be air-permeable if air holes are formed in it by processing or the like.

[0014] The ceramic porous body 1 has, for example, a porosity of 10% to 50%, an average pore diameter of 20 μm to 100 μm, and an average particle diameter of 50 μm to 300 μm. If the porosity and pore diameter are within these ranges, the adsorption strength can be improved while achieving a balance between the strength and rigidity of the member and the airflow resistance.

[0015] The porosity and pore diameter values ​​can be determined, for example, by cutting the member to be measured to an appropriate size and subjecting it to mercury intrusion porosimetry in accordance with JIS R 1655-2003. Alternatively, any cross section of the member to be measured can be observed using an electron microscope or optical microscope, and the observed image can be subjected to image processing to determine the values. The porosity of porous bodies can be measured by mercury intrusion porosimetry, and the porosity of dense bodies can be measured by cross-sectional observation.

[0016] The porosity (closed porosity) of a dense body is measured by the following method. First, a cross section of the ceramic is mirror-polished and the resulting surface is observed at a magnification of 500 times. Specifically, polishing is performed in the following manner. (1) First Polishing: Average particle diameter D ５０ (2) Second polishing: polishing with a diamond disc using diamond abrasive grains with an average grain size D ５０ (3) Third polishing: polishing with a copper plate using diamond abrasive grains with an average grain size D ５０ Polishing with a tin plate using 0.5 μm diamond abrasive grains.

[0017] An average area is selected from the observed surface, for example, an area of ​​1.06 × 10 ６ μm ２ The area of ​​the sample (1190 μm in horizontal direction and 890 μm in vertical direction) is photographed with a scanning electron microscope to obtain an observation image at 100x magnification. This observation image can be used to determine the area ratio of closed pores using a method called particle analysis, using image analysis software "A-zo-kun (ver. 2.52)" (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.). Hereinafter, when the image analysis software "A-zo-kun" is mentioned, it refers to the image analysis software manufactured by Asahi Kasei Engineering Co., Ltd.

[0018] The setting conditions for this method are, for example, a threshold value which is an index showing the brightness of an image of 91, brightness as dark, and a small figure removal area of ​​1 μm２ The threshold value can be adjusted according to the brightness of the observed image. The brightness is set to dark, the binarization method is set to manual, and the small figure removal area is set to 1 μm ２ With the noise reduction filter enabled, the threshold value can be adjusted so that the markers appearing in the observed image match the shape of the closed pores.

[0019] Among these ceramics, the ceramic forming the ceramic porous body 1 is preferably a ceramic containing alumina as its main component. In this specification, "main component" refers to a component that is contained in a proportion of 50% by mass or more, assuming that the total of the components constituting the ceramic is 100% by mass. Each component contained in the ceramic can be identified, for example, using an X-ray diffraction apparatus using CuKα radiation. The content of each component can be determined, for example, using an ICP (Inductively Coupled Plasma) emission spectrometer or an X-ray fluorescence analyzer.

[0020] The shape and size of the porous ceramic body 1 are not limited and are appropriately determined depending on the application of the resulting vacuum chuck 10 or the shape of the object to be adsorbed. The porous ceramic body 1 may have, for example, a circular, elliptical, or polygonal shape (triangular, rectangular, pentagonal, hexagonal, etc.) when viewed from above. In the case of a polygonal shape, the shape of the porous ceramic body 1 may be a regular polygon or a scalene polygon.

[0021] The size of the porous ceramic body 1 is not limited, and may be, for example, a diameter of 50 mm or more and 500 mm or less. When the porous ceramic body 1 has an elliptical shape, both the major axis and the minor axis may be within the above ranges. When the porous ceramic body 1 has a polygonal shape, the length of one side is, for example, 50 mm or more and 500 mm or less. The thickness of the porous ceramic body 1 is, for example, 10 mm or more and 50 mm or less.

[0022] The support part 2 is a member that supports the porous ceramic body 1. As shown in FIG. 1 , the support part 2 has an annular second surface 2a that is positioned so as to surround the first surface 1a of the porous ceramic body 1. The shape and size of the support part 2 are not limited as long as they are capable of supporting the porous ceramic body 1. Furthermore, the material and raw materials of the support part 2 are also not limited, and for example, the support part 2 may be made of ceramics that have the same main component as the porous ceramic body 1. If the ceramics are the same, there is a small difference in the thermal expansion coefficient. Therefore, deformation when heat is applied is small.

[0023] As shown in FIG. 1 , when an integrally molded product 3 in which a porous ceramic body 1 and a support portion 2 are integrated is used, the porous ceramic body 1 and the support portion 2 are formed from the same raw material. In the integrally molded product 3, the boundary between the porous ceramic body 1 and the support portion 2 is the second surface 2a. The portion located above the second surface 2a corresponds to the porous ceramic body 1, and the portion located below the second surface 2a corresponds to the support portion 2. The integrally molded product 3 may be placed on a dense substrate 4. Specifically, as shown in FIG. 1 , the integrally molded product 3 is placed on the substrate 4 so that the surface opposite to the first surface 1a is in contact with the substrate 4. The substrate 4 may be, for example, a dense ceramic.

[0024] As shown in Figures 1 and 5, the first film 6 is positioned so as to cover the first surface 1a of the porous ceramic body 1 to the second surface 2a of the support portion 2. In Figure 1, specifically, the first film 6 is positioned so as to cover the surfaces of the integrally molded product 3 (the first surface 1a, the first side surface 81, and the second surface 2a). The first film 6 is breathable and semi-conductive. In this specification, "semi-conductive" means that the resistance value is 1E+05Ω to 1E+10Ω. It is necessary for the placed object to be adsorbed onto the first surface 1a of the porous ceramic body 1 by suction through the suction holes 5. For this reason, the first film 6 must be breathable.

[0025] Furthermore, the second film 7 is positioned so as to cover at least the first film 6 positioned on the second surface 2 a and the side surface (third side surface 83) of the support part 2. The second film 7 has a lower resistance than the first film 6 and is a film that does not have breathability.

[0026] The use of a semiconductive first film 6 reduces the occurrence of sparks. The use of a second film 7 with lower resistance than the first film 6 efficiently removes static electricity. Furthermore, the overlapping and contact of the first film 6 and the second film 7 on the second surface 2a also improves electrical connection. A good connection can be achieved if the width of the overlapping portion between the first film 6 and the second film 7 is, for example, 1 mm or more. If both the first film 6 and the second film 7 are semiconductive, it becomes difficult to quickly remove generated static electricity. On the other hand, if both the first film 6 and the second film 7 are low-resistivity films, it becomes difficult to reduce the occurrence of sparks.

[0027] The first film 6 is not limited to any particular material as long as it is breathable and semiconductive, and examples thereof include films formed from ceramics and resins. Among these, it is preferable that the first film 6 be a film formed from ceramics. A film formed from ceramics has a small difference in thermal expansion from the ceramic porous body 1, and is less likely to deform or undergo stress when the temperature changes. Furthermore, a film formed from ceramics has good processing precision, making it easy to obtain an adsorption surface with good flatness. Examples of films formed from ceramics include films whose main components are alumina, titanium oxide, zinc oxide, silicon carbide, diamond-like carbon, silicon nitride, boron nitride, and aluminum nitride.

[0028] It is particularly preferable that the first film 6 has the same main component as the ceramic porous body 1, since this reduces the difference in thermal expansion (deformation and stress due to temperature changes). If the main component of the ceramic porous body 1 is alumina, the first film 6 is preferably formed of a ceramic containing alumina as the main component and at least one of titanium oxide and zinc oxide.

[0029] The resistivity of the first film 6 can be adjusted by the content of titanium oxide and zinc oxide relative to alumina. The higher the content of titanium oxide and zinc oxide, the lower the resistance of the film. The resistivity of the first film 6 is preferably 1E+05Ω to 1E+10Ω, and the content of titanium oxide and zinc oxide should be adjusted so that the resistivity falls within this range.

[0030] When the first film 6 is made of ceramic, the first film 6 may be a ceramic sprayed film. Film formation by spraying can be performed at a relatively low temperature, with little thermal stress, and it is relatively easy to thicken the film (a uniform film remains even when the surface after film formation is flattened). Examples of ceramic films that can be formed by spraying include alumina, titanium oxide, and zinc oxide.

[0031] When the ceramic porous body 1 is made of a ceramic containing alumina as a main component and the first film 6 is made of a ceramic containing alumina and at least one of titanium oxide and zinc oxide, the difference in physical properties (thermal expansion coefficient, Young's modulus, etc.) between the components is small, which reduces thermal stress and improves processing accuracy such as flatness.

[0032] The second film 7 is not limited to a specific material as long as it has a lower resistance than the first film 6. If the support 2 is porous, the second film 7 may be a non-permeable film. Examples of the second film 7 include films made of ceramic, resin, and metal. Among these, the second film 7 is preferably a ceramic film. Examples of ceramic films include films made from titanium oxide, zinc oxide, lead oxide, alumina, and diamond-like carbon. In particular, the second film 7 is preferably made of a ceramic containing titanium oxide as a primary component. When the second film 7 is made of a ceramic containing titanium oxide as a primary component, it has high conductivity and can quickly remove static electricity. The resistance of the second film 7 may be, for example, 20 Ω or less.

[0033] When the first film 6 and the second film 7 have the same main component, for example, when the main component is alumina, the second film 7 may be adjusted so that the content of the component added for controlling conductivity is larger than that of the first film 6. When the main component is diamond-like carbon, the second film 7 may be adjusted so that the ratio of SP2 bonds is larger than that of the first film 6.

[0034] When the second film 7 is made of ceramic, the second film 7 may also be a ceramic sprayed film. The second film 7 may be denser and thicker than the first film 6. When the second film 7 is denser and thicker than the first film 6, its conductivity is higher. As a result, generated static electricity is more quickly removed. The first film 6 must be breathable. The first film 6 may be porous or dense as long as it is thick enough not to block the interconnected pores opening to the first surface 1a of the ceramic porous body 1. The first film 6 may have a thickness of, for example, 10 μm or more and 200 μm or less. The second film 7 is preferably dense. The second film 7 may have a thickness of, for example, 100 μm or more and 2 mm or less, and may have a closed porosity of 10 area% or less.

[0035] The colors of the first film 6 and the second film 7 are not limited and may be achromatic colors such as white, black, and gray, or may be chromatic colors. The first film 6 and the second film 7 may have the same color or different colors. For example, if the first film 6 and the second film 7 have different colors, the outline of the first film 6 becomes clear. As a result, when an object is placed on the placement surface (first surface 1a), it can be placed only on the first film 6 or can be placed so that it overlaps the second film 7 as well.

[0036] When the first film 6 is formed of, for example, a ceramic containing alumina and titanium oxide, the color and resistivity of the first film 6 can be adjusted by the content of titanium oxide and zinc oxide. By including titanium oxide in a ratio of 30% by mass to 50% by mass, a semiconductive black first film 6 is formed. Therefore, when a white object is placed on the first film 6, the outline of the object can be clearly defined. On the other hand, by including zinc oxide in a ratio of 30% by mass to 50% by mass, a semiconductive white first film 6 is formed. Therefore, when a black object is placed on the first film 6, the outline of the object can be clearly defined.

[0037] Both titanium oxide and zinc oxide impart semiconductivity to alumina. Therefore, by including them in the above-mentioned proportions, spark generation can be more efficiently reduced. When titanium oxide and zinc oxide are included in a total proportion of 30% by mass or more and 50% by mass or less, a grayish, semiconductive first film 6 is formed. Therefore, the outline of the placed object can be clearly defined whether a black or white object is placed on the surface.

[0038] 1, the second surface 2a may be located at a lower position than the first surface 1a. When the second surface 2a is located at a lower position than the first surface 1a, the thickness of the first film 6 and the second film 7 that are located overlapping on the second surface 2a can be ensured to be sufficient. As a result, one of the films does not become too thin, and the electrical connection between the first film 6 and the second film 7 can be improved. The height from the second surface 2a to the first surface 1a is, for example, 50 μm or more.

[0039] Furthermore, the second film 7 located on the second surface 2a may be flush with the first film 6 located on the first surface 1a or may be located at a lower level than the first film 6 located on the first surface 1a. If the second film 7 located on the second surface 2a is flush with the first film 6 located on the first surface 1a, high flatness can be achieved by lapping. On the other hand, if the second film 7 located on the second surface 2a is located at a lower level than the first film 6 located on the first surface 1a, an object placed on the second surface 2a is less likely to come into contact with the second film 7. As a result, spark generation is more efficiently reduced.

[0040] In the vacuum chuck 10 according to one embodiment, the first side surface 81 located between the first surface 1a and the second surface 2a may be substantially perpendicular to the first surface 1a and the second surface 2a as shown in FIG. 1 , or may be inclined outward from the first surface 1a to the second surface 2a as shown in FIG. 2 . FIG. 2 is an enlarged explanatory view illustrating a modified example of the region X shown in FIG. 1 . In particular, when the first side surface 81 is inclined outward from the first surface 1a to the second surface 2a, the first film 6 bends gently rather than perpendicularly. This further reduces breakage of the first film 6.

[0041] The corner C1 between the first surface 1a and the first side surface 81 may be substantially perpendicular to the first surface 1a and the second surface 2a as shown in Fig. 1, or may be chamfered as shown in Fig. 2. In particular, when the corner C1 is chamfered, the first film 6 bends gently rather than perpendicularly. This further reduces breakage of the first film 6.

[0042] A corner C2 formed by the second surface 2a and the third side surface 83, which is the outer surface of the support portion 2, may be approximately perpendicular to the second surface 2a as shown in Fig. 1, or may be chamfered as shown in Fig. 2. In particular, when the corner C2 is chamfered, the second film 7 bends gently at the corner C2 rather than bending perpendicularly. This further reduces breakage of the second film 7.

[0043] The second surface 2a may be substantially parallel to the first surface 1a as shown in Fig. 1, or may be inclined so as to descend outward as shown in Fig. 2. In particular, when the second surface 2a is inclined so as to descend outward, the total thickness of the first film 6 and the second film 7 increases toward the outer periphery (third side surface 83). As a result, peeling of the first film 6 and the second film 7 from the third side surface 83 side can be reduced. Furthermore, bending of the second film 7 is also gentler, further reducing breakage of the second film 7.

[0044] Next, a vacuum chuck according to another embodiment of the present disclosure will be described with reference to Figures 3 and 4. As shown in Figure 3, in a vacuum chuck 20 according to another embodiment, a porous ceramic body 1 and a support portion 2 are formed of different members. That is, the support portion 2 is formed of a dense ceramic body 21. Figure 3 is a cross-sectional view showing a vacuum chuck 20 according to another embodiment of the present disclosure. The same members as those in the vacuum chuck 10 according to the first embodiment are designated by the same reference numerals as those in Figures 1 and 2, and detailed description thereof will be omitted.

[0045] The dense ceramic body 21 is superior to porous ceramics in mechanical strength, thermal conductivity, airtightness, and the like. The dense ceramic body 21 is not limited as long as it is made of a dense ceramic. Examples of ceramics that form the dense ceramic body 21 include ceramics containing oxides such as aluminum oxide (alumina), titanium oxide, and zinc oxide, carbides such as silicon carbide, and nitrides such as silicon nitride, boron nitride, and aluminum nitride. The closed porosity of the dense ceramic body 21 is, for example, 10 area% or less.

[0046] The dense ceramic body 21 may be formed from the same material as the porous ceramic body 1. For example, when the porous ceramic body 1 is formed from a ceramic containing alumina as a main component, the dense ceramic body 21 may also be formed from a ceramic containing alumina as a main component.

[0047] The shape and size of the dense ceramic body 21 are not limited and are set appropriately depending on the application of the resulting vacuum chuck 20 and the shape of the porous ceramic body 1. The shape of the dense ceramic body 21 is not limited. The dense ceramic body 21 may have, for example, a circular, elliptical, or polygonal shape (triangular, rectangular, pentagonal, hexagonal, etc.) when viewed from above. In the case of a polygonal shape, the shape of the dense ceramic body 21 may be a regular polygon or a scalene polygon.

[0048] The dense ceramic body 21 has a recess 211 for accommodating the porous ceramic body 1. The recess 211 is formed according to the shape and size of the porous ceramic body 1. The third surface 2b, which is connected to the wall surface of the recess 211, is positioned substantially flush with the first surface 1a, as shown in Fig. 3. "Substantially flush" also includes cases where the first surface 1a and the third surface 2b are not completely flush, but where there is a difference of 100 µm or less between the first surface 1a and the third surface 2b.

[0049] In a vacuum chuck 20 according to another embodiment, the second surface 2 a is located on the outer peripheral edge side of the third surface 2 b, as shown in Fig. 3. The height from the second surface 2 a to the third surface 2 b is, for example, 500 µm or more.

[0050] In a vacuum chuck 20 according to another embodiment, the second side surface 82 located between the third surface 2b and the second surface 2a may be substantially perpendicular to the third surface 2b and the second surface 2a, as shown in Fig. 3, or may be inclined outward from the third surface 2b to the second surface 2a, as shown in Fig. 4. Fig. 4 is an enlarged view illustrating a modified example of region Y shown in Fig. 3. In particular, when the second side surface 82 is inclined outward from the third surface 2b to the second surface 2a, the first film 6 bends gently rather than perpendicularly. This further reduces breakage of the first film 6.

[0051] The corner C3 between the third surface 2b and the second side surface 82 may be substantially perpendicular to the third surface 2b and the second surface 2a as shown in Fig. 3, or may be chamfered as shown in Fig. 4. In particular, when the corner C3 is chamfered, the first film 6 bends gently rather than perpendicularly. This further reduces breakage of the first film 6.

[0052] As shown in Figures 1 and 3, the vacuum chucks 10 and 20 are formed with suction holes 5. The suction holes 5 have openings on the surface of the vacuum chucks 10 and 20 opposite the first surface 1a on which an object is placed, and penetrate to the underside of the porous ceramic body 1 or the underside of the support portion 2 made of a porous body. The suction holes 5 are connected to a suction source (not shown), such as a vacuum pump. When the suction source is activated, the suction holes 5 become a path for sucking air, and the object is suctioned and held via the porous ceramic body 1 (first surface 1a).

[0053] Next, a method for manufacturing the suction member of the present disclosure will be described. The method for manufacturing the vacuum chuck 10 according to one embodiment of the present disclosure includes the following steps (a) to (e): (a) preparing a porous ceramic body having an upper surface, a lower surface, and a side surface; (b) forming a first surface on the upper surface of the porous ceramic body and a ring-shaped second surface located on the periphery of the upper surface so as to surround the first surface; (c) coating the first and second surfaces with a first film that is permeable and semiconductive; (d) coating at least the first film located on the second surface and the side surface of the porous ceramic body with a second film that has lower resistance than the first film and is not permeable; and (e) simultaneously grinding the first and second films to make the first and second films approximately flush with each other.

[0054] Step (a) is a step of preparing a porous ceramic body having an upper surface, a lower surface, and a side surface. This porous ceramic body is processed into an integrally molded product 3 in which the porous ceramic body 1 and a support portion 2 are integrated, as shown in Figure 1. The ceramic forming the porous ceramic body is the same as the ceramic forming the porous ceramic body 1, and a detailed description thereof will be omitted. An example of a method for producing a porous ceramic body containing alumina as a main component will be described below.

[0055] First, the average particle size D ５０ aluminum oxide powder having an average particle size D of 50 μm or more and 250 μm or less; ５０ A glass powder having a particle size of 4 μm or more and 40 μm or less, water, and a binder are mixed. The ratio of the glass powder to 100 parts by mass of aluminum oxide powder is 5 parts by mass or more and 10 parts by mass or less. The glass powder becomes a glass component that binds together aluminum oxide crystal particles that form a ceramic porous body through heat treatment, which will be described later, and has a softening point of 750°C or more and 940°C or less. The ratio of water is 5 parts by mass or more and 10 parts by mass or less, based on a total of 100 parts by mass of the aluminum oxide powder and the glass powder. Other polar solvents may be used instead of water.

[0056] The mixed aluminum oxide powder and glass powder are granulated using various granulators such as a tumbling granulator, a spray dryer, a compression granulator, and an extrusion granulator to obtain granules.

[0057] Next, the obtained granules are filled into a mold and press-molded by hydrostatic pressure to obtain a molded body, which is then heat-treated, for example, in an air atmosphere or a nitrogen atmosphere at a temperature of 900°C or higher and 1300°C or lower to obtain a ceramic porous body.

[0058] Step (b) is a step of forming a first surface 1a and an annular second surface 2a on the upper surface of the porous ceramic body obtained in step (a) so as to surround the first surface 1a and be located at the peripheral portion of the upper surface. As shown in Fig. 1, the second surface 2a is preferably formed at a lower position than the first surface 1a. For example, the peripheral portion of the upper surface of the porous ceramic body may be removed by cutting or grinding.

[0059] As shown in Figure 2, when forming the second surface 2a, if necessary, a first side surface 81 located between the first surface 1a and the second surface 2a may be machined so as to be inclined outward. The second surface 2a may also be machined so as to be inclined so as to be lower toward the outside. Furthermore, a corner C1 formed by the first surface 1a and the first side surface 81 located between the first surface 1a and the second surface 2a may be subjected to chamfering. A corner C2 formed by the second surface 2a and a third side surface 83, which is the outer surface of the support portion 2 (integrally molded product 3), may also be subjected to chamfering.

[0060] Step (c) is a step of coating the first surface 1a to the second surface 2a with a first film 6 that is breathable and semi-conductive. The first film 6 is as described above, and a detailed description thereof will be omitted. Below, an example will be described in which plasma spraying is used as a method for forming the first film 6 containing alumina and titanium oxide.

[0061] The ceramic porous body 1 is placed in a plasma spraying device. A voltage is applied between the anode and cathode to generate a DC arc, and a gas such as argon is supplied to generate a plasma jet. A spray powder consisting of a mixed powder of alumina and titanium oxide is supplied into the plasma jet using argon gas or the like to form a sprayed film (first film 6) on the surface of the ceramic porous body 1. The mixing ratio of alumina and titanium oxide is adjusted so that the first film 6 has the desired color (brightness) and resistance value. It is preferable to cover the area of ​​the surface of the ceramic porous body 1 where the first film 6 is not to be formed with a mask.

[0062] Step (d) is a step of covering at least the first film 6 located on the second surface 2a and the side surface (third side surface 83) of the ceramic porous body 1 with a second film 7 that has lower resistance than the first film 6 and is not breathable. The second film 7 is as described above, and a detailed description thereof will be omitted. Hereinafter, the second film 7 containing titanium oxide as a main component can be formed using a thermal spray powder containing titanium oxide as a main component in the same manner as the first film 6.

[0063] In step (e), the first film 6 and the second film 7 are simultaneously ground to make the first film 6 and the second film 7 substantially flush with each other. In steps (c) and (d), the first film 6 and the second film 7 are formed to be slightly thicker than the desired thickness, and in step (e), the first film 6 and the second film 7 are ground together by, for example, at least one of surface grinding and lapping, to make the first film 6 and the second film 7 substantially flush with each other.

[0064] By these steps (a) to (e), the vacuum chuck 10 according to one embodiment as shown in FIGS. 1 and 5 is obtained.

[0065] Next, a method for manufacturing a vacuum chuck 20 according to another embodiment of the present disclosure includes the following steps (A) to (F): (A) preparing a porous ceramic body and a dense ceramic body having a recess for accommodating the porous ceramic body; (B) joining the porous ceramic body to the recess and processing the porous ceramic body and the dense ceramic body so that they are substantially flush with each other, thereby forming a first surface on the upper surface of the porous ceramic body; (C) forming a third surface on the dense ceramic body, the third surface surrounding the recess, connecting to the wall surface of the recess, and being substantially flush with the first surface, and a second surface on the outer periphery of the third surface so as to surround the third surface; (D) coating the first and second surfaces with a first film that is permeable and semiconductive; (E) coating at least the first film and the side surface of the dense ceramic body that are located on the second surface with a second film that has a lower resistance than the first film; and (F) simultaneously grinding the first and second films to make the first and second films substantially flush with each other.

[0066] Step (A) is a step of preparing a porous ceramic body 1 and a dense ceramic body 21 having a recess 211 for accommodating the porous ceramic body 1. The porous ceramic body 1 is a thinner version of the porous ceramic body described in step (a) above, and a detailed description thereof will be omitted. The dense ceramic body 21 is as described above, and a detailed description thereof will be omitted. An example of a method for manufacturing a dense ceramic body 21 containing alumina as a main component will be described below.

[0067] First, aluminum oxide powder (purity of 99.9% by mass or more), magnesium hydroxide powder, silicon oxide powder, and calcium carbonate powder are charged into a grinding mill together with a solvent (ion-exchanged water) and a dispersant. ５０ After the powder is pulverized to a particle size of 1.5 μm or less, an organic binder, a plasticizer, and a release agent are added and mixed to obtain a slurry.

[0068] The content of magnesium hydroxide powder is 0.2% by mass or more and 0.5% by mass or less, the content of silicon oxide powder is 0.03% by mass or more and 0.06% by mass or less, the content of calcium carbonate powder is 0.015% by mass or more and 0.025% by mass or less, and the remainder is aluminum oxide powder and unavoidable impurities, based on a total of 100% by mass of the above powders.

[0069] Examples of organic binders include acrylic emulsion, polyvinyl alcohol, polyethylene glycol, polyethylene oxide, etc. The amount of organic binder added is 3 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the powder.

[0070] The slurry is granulated using a spray dryer to obtain granules. The obtained granules are then filled into a mold and hydrostatically pressed to obtain a molded body. The molding pressure is, for example, 78 MPa to 128 MPa. The obtained molded body is processed to obtain a precursor having recesses, etc. This precursor is fired in an air atmosphere at a temperature of 1500°C to 1700°C for a holding time of 4 hours to 6 hours to obtain a sintered body. The sintered body is ground to obtain a dense ceramic body 21.

[0071] The recesses 211 may be formed when the molded body is obtained before firing, or may be formed after firing by subjecting the sintered body to cutting or grinding.

[0072] Step (B) is a step of joining the porous ceramic body 1 to the recess 211, and processing the porous ceramic body 1 and the dense ceramic body 21 so that they are substantially flush with each other, thereby forming a first surface 1a on the upper surface of the porous ceramic body 1. The method of joining the porous ceramic body 1 and the dense ceramic body 21 (recess 211) is not limited, and they can be joined using an adhesive, for example.

[0073] After the porous ceramic body 1 is bonded to the recess 211, the porous ceramic body 1 and the dense ceramic body 21 are processed so that they are substantially flush with each other. Specifically, the porous ceramic body 1 and the dense ceramic body 21 may be processed so that they are substantially flush with each other by grinding, polishing, or the like.

[0074] 3, step (C) is a step of forming a third surface 2b in the ceramic dense body 21. The third surface 2b surrounds the recess 211, is connected to the wall surface of the recess 211, and is positioned approximately flush with the first surface 1a, and a second surface 2a is formed on the outer periphery of the third surface 2b so as to surround the third surface 2b. The second surface 2a is preferably formed at a lower position than the first surface 1a. The method for forming the second surface 2a is the same as that of step (b) above, and a detailed description thereof will be omitted.

[0075] The third surface 2b located on the dense ceramic body 21 is formed in the above-described step (B) so that the porous ceramic body 1 and the dense ceramic body 21 are substantially flush with each other. Therefore, the formation of the second surface 2a inevitably results in the formation of the third surface 2b.

[0076] As shown in Figure 4, when forming the second surface 2a, if necessary, the second side surface 82 located between the third surface 2b and the second surface 2a may be machined so as to be inclined outward. The second surface 2a may also be machined so as to be inclined so as to be lower toward the outside. Furthermore, a corner C3 formed by the third surface 2b and the second side surface 82 located between the third surface 2b and the second surface 2a may be chamfered. A corner C2 formed by the second surface 2a and the third side surface 83, which is the outer surface of the support portion 2 (the dense ceramic body 21), may also be chamfered.

[0077] Step (D) is a step of coating the first surface 1 a to the second surface 2 a with the breathable and semi-conductive first film 6. The first film 6 and the method for forming the first film 6 are as described above, and detailed description thereof will be omitted.

[0078] Step (E) is a step of covering at least the first film 6 located on the second surface 2a and the side surface (third side surface 83) of the ceramic dense body 21 with the second film 7, which has a lower resistance than the first film 6. The second film 7 and the method for forming the second film 7 are as described above, and a detailed description thereof will be omitted.

[0079] Step (F) is a step of simultaneously grinding the first film 6 and the second film 7 to make the first film 6 and the second film 7 substantially flush with each other. Step (F) is as described in step (e) above, and a detailed description thereof will be omitted.

[0080] In this manner, steps (A) to (F) are performed to obtain a vacuum chuck 20 according to another embodiment as shown in Fig. 3. The vacuum chuck 10 according to the embodiment and the vacuum chuck 20 according to another embodiment obtained in this manner are used as components of a processing device or the like that fixes an object to be attracted, such as a semiconductor wafer, and processes the surface of the object to be attracted.

[0081] Although the embodiments of the present disclosure have been described above, the invention according to the present disclosure is not limited to the above embodiments, and various modifications and improvements are possible within the scope of the present disclosure as shown in (1), (12), and (13) below.

[0082] (1) A vacuum chuck according to the present disclosure includes a plate-shaped ceramic porous body having a first surface on the mounting surface side and pores communicating in the thickness direction, a support portion having an annular second surface positioned so as to surround the first surface, a first film that is air-permeable and semi-conductive, and a second film that has lower resistance than the first film. At least one of the support portion and the second film is not air-permeable. The first film covers the first surface and the second surface. The second film covers at least the side surfaces of the first film and the support portion positioned on the second surface.

[0083] The present disclosure further discloses the following embodiments (2) to (11).

[0084] (2) In the vacuum chuck described in (1) above, the porous ceramic body and the support portion are integrally molded. (3) In the vacuum chuck described in (1) above, the support portion is a dense ceramic body having a recess for accommodating the porous ceramic body. The support portion has a third surface surrounding the recess, connected to the wall of the recess, and positioned approximately flush with the first surface, and a second surface positioned on the outer periphery of the third surface and surrounding the third surface. (4) In the vacuum chuck described in (2) above, the integrally molded body is placed so that the surface opposite the first surface is in contact with the substrate. (5) In the vacuum chuck described in any of (1) to (4) above, the second surface is positioned lower than the first surface. The second film positioned on the second surface is either flush with the first film positioned on the first surface or lower than the first film positioned on the first surface. (6) In the vacuum chuck described in any of (1) to (5) above, the first film and the second film are thermally sprayed ceramic films. (7) In the vacuum chuck described in any one of (1) to (6) above, the first film has a different color from the second film. (8) In the vacuum chuck described in any one of (2) and (4) to (7) above, the porous ceramic body is primarily composed of alumina, and the first film contains alumina and at least one of titanium oxide and zinc oxide. (9) In the vacuum chuck described in any one of (3) and (5) to (7) above, the porous ceramic body and the dense ceramic body are primarily composed of alumina, and the first film contains alumina and at least one of titanium oxide and zinc oxide. (10) In the vacuum chuck described in any one of (1) to (9) above, the second film contains titanium oxide as a primary component. (11) In the vacuum chuck described in any one of (1) to (10) above, the second film is denser and thicker than the first film.

[0085] (12) A method for manufacturing a vacuum chuck according to the present disclosure includes the steps of: preparing a porous ceramic body having an upper surface, a lower surface, and a side surface and having pores communicating in a thickness direction; forming a first surface on the upper surface of the porous ceramic body and a ring-shaped second surface located on the periphery of the upper surface so as to surround the first surface; coating the first surface and the second surface with a first film that is permeable and semi-conductive; coating at least the first film located on the second surface and the side surface of the porous ceramic body with a second film that has a lower resistance than the first film and is not permeable; and simultaneously grinding the first film and the second film to make the first film and the second film approximately flush with each other.

[0086] (13) Another method for manufacturing a vacuum chuck according to the present disclosure includes the steps of: preparing a plate-shaped porous ceramic body having pores communicating in the thickness direction; and a dense ceramic body having a recess for accommodating the porous ceramic body; joining the porous ceramic body to the recess and processing the porous ceramic body so that the porous ceramic body and the dense ceramic body are substantially flush with each other to form a first surface on the upper surface of the porous ceramic body; forming on the dense ceramic body a third surface that surrounds the recess, connects to a wall surface of the recess, and is substantially flush with the first surface; and forming on the dense ceramic body a second surface that surrounds the third surface and is located on the outer periphery of the third surface; coating from the first surface to the second surface with a first film that is air-permeable and semi-conductive; coating at least the first film and the side surface of the dense ceramic body that are located on the second surface with a second film that has a lower resistance than the first film; and simultaneously grinding the first film and the second film to make the first film and the second film substantially flush with each other.

[0087] REFERENCE SIGNS LIST 1 ceramic porous body 1a first surface 2 support portion 21 dense ceramic body 211 recess 2a second surface 2b third surface 3 integrally molded product 4 dense substrate 5 suction hole 6 first film 7 second film 81 first side surface 82 second side surface 83 third side surface 10, 20 vacuum chuck

Claims

1. a plate-shaped ceramic porous body having a first surface that is a mounting surface side and pores that communicate in a thickness direction; a support portion having an annular second surface positioned so as to surround the first surface; a first film that is breathable and semi-conductive; a second film having a lower resistance than the first film; Including, At least one of the support portion and the second film is not breathable, the first film covers the first surface and the second surface, the second film covers at least the side surfaces of the first film and the support portion located on the second surface; Vacuum chuck.

2. 2. The vacuum chuck according to claim 1, wherein the porous ceramic body and the support portion are integrally molded.

3. the support portion is a dense ceramic body having a recess for accommodating the porous ceramic body, a third surface that surrounds the recess, is connected to a wall surface of the recess, and is positioned approximately flush with the first surface, on the outer peripheral edge side of the recess; and a second surface that surrounds the third surface and is positioned on the outer peripheral edge side of the third surface.

10. The vacuum chuck of claim 1.

4. The vacuum chuck according to claim 2 , wherein the single-piece molded article is placed so that a surface opposite to the first surface is in contact with a substrate.

5. the second surface is located at a lower position than the first surface, The second film located on the second surface is flush with the first film located on the first surface or is located at a lower level than the first film located on the first surface.

5. The vacuum chuck according to claim 1.

6. 5. The vacuum chuck according to claim 1, wherein the first film and the second film are ceramic sprayed films.

7. The vacuum chuck of claim 1 , wherein the first film has a different color than the second film.

8. 5. The vacuum chuck according to claim 2, wherein the porous ceramic body is composed mainly of alumina, and the first film contains alumina and at least one of titanium oxide and zinc oxide.

9. 4. The vacuum chuck according to claim 3, wherein the porous ceramic body and the dense ceramic body are primarily composed of alumina, and the first film contains alumina and at least one of titanium oxide and zinc oxide.

10. 5. The vacuum chuck according to claim 1, wherein the second film contains titanium oxide as a main component.

11. The vacuum chuck according to claim 1 , wherein the second film is denser and thicker than the first film.

12. preparing a ceramic porous body having an upper surface, a lower surface, and a side surface and having pores communicating in a thickness direction; forming a first surface on the upper surface of the ceramic porous body and a ring-shaped second surface located on the periphery of the upper surface so as to surround the first surface; coating a first film having breathability and semi-conductivity from the first surface to the second surface; a step of covering at least the side surfaces of the first film and the ceramic porous body located on the second surface with a second film having a lower resistance than the first film and no gas permeability; grinding the first film and the second film simultaneously to make the first film and the second film substantially flush with each other; A method for manufacturing a vacuum chuck, comprising:

13. a step of preparing a plate-shaped porous ceramic body having pores communicating in a thickness direction, and a dense ceramic body having a recess for accommodating the porous ceramic body; bonding the porous ceramic body to the recess and processing the porous ceramic body so that the porous ceramic body and the dense ceramic body are substantially flush with each other to form a first surface on the upper surface of the porous ceramic body; forming a third surface in the ceramic dense body, the third surface surrounding the recess, connected to a wall surface of the recess, and positioned substantially flush with the first surface, and a second surface positioned on an outer peripheral edge side of the third surface so as to surround the third surface; coating a first film having breathability and semi-conductivity from the first surface to the second surface; a step of covering at least the first film and a side surface of the ceramic dense body located on the second surface with a second film having a lower resistance than the first film; grinding the first film and the second film simultaneously to make the first film and the second film substantially flush with each other; A method for manufacturing a vacuum chuck, comprising: