Suction member

Abstract

This suction member includes a ceramic porous body, a support part, a first film, and a second film. The ceramic porous body has a first surface including a mounting surface, an annular second surface positioned at a height different from that of the first surface and surrounding the first surface, and a first side surface positioned between the first surface and the second surface, and has pores communicating in the thickness direction. The support part supports the ceramic porous body. The first film has conductivity. The second film has a lower resistance than that of the first film. The first film covers the first surface, the first side surface, and the second surface. The second film covers the first film positioned on the first side surface and the second surface.

Description

Adsorption material

[0001] The present disclosure relates to an adsorption member.

[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 adsorption member according to the present disclosure includes a ceramic porous body, a support, a first membrane, and a second membrane. The ceramic porous body has a first surface including a mounting surface, an annular second surface located at a different height from the first surface and surrounding the first surface, and a first side surface located between the first and second surfaces, and has pores communicating in the thickness direction. The support supports the ceramic porous body. The first membrane is conductive. The second membrane has lower resistance than the first membrane. The first membrane covers the first surface, the first side surface, and the second surface. The second membrane covers the first membrane located on the first side surface and the second surface.

[0005] Fig. 1 is a cross-sectional view showing an example of an adsorption member according to an embodiment of the present disclosure. Fig. 2 is an enlarged explanatory view for explaining another example of region X shown in Fig. 1. Fig. 3 is a cross-sectional view showing an example of an adsorption member according to another embodiment of the present disclosure. Fig. 4 is an enlarged explanatory view for explaining another example of region Y shown in Fig. 3. Fig. 5 is an enlarged explanatory view for explaining yet another example of region Y shown in Fig. 3. Fig. 6 is a perspective view of the adsorption member shown in Fig. 3.

[0006] In recent years, there has been a demand for adsorption members that can more efficiently remove generated static electricity. To prevent sparks due to sudden discharge upon contact with an adsorbed object, the coating must be conductive. 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.

[0007] Therefore, it is desired to provide an attraction member that can efficiently remove generated static electricity and reduce the occurrence of sparks due to sudden discharge.

[0008] An adsorption member according to an embodiment of the present disclosure will be described with reference to Figures 1 and 2. Figure 1 is a cross-sectional view showing an example of an adsorption member according to an embodiment of the present disclosure. As shown in Figure 1, an adsorption member 10 according to this embodiment includes a porous ceramic body 1, a support portion 2, a first film 31, and a second film 32.

[0009] 1, the suction member 10 according to this embodiment has a structure in which a porous ceramic body 1 is placed on a support portion 2. An example of the suction member 10 is a vacuum chuck.

[0010] The porous ceramic body 1 has a first surface 11, which is a mounting surface on which an object such as a semiconductor wafer is placed. The porous ceramic body 1 is formed 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 have air permeability. In other words, in this specification, "porous body" refers to an object that contains interconnected pores within itself and has air permeability.

[0011] "Breathable" generally means having the property of allowing gas to pass through. However, in this specification, "breathable" means having a degree of breathability that allows the surface of the porous body to adsorb and hold an object such as a substrate when the back surface of the porous body is suctioned with a vacuum pump. When a suction tube is connected to a vacuum pump and suction is performed, the pressure difference (pressure loss) between the suction tube and the atmospheric pressure may be 90 kPa or less. In contrast, an object that does not have interconnecting pores and is airtight is called a dense material. A dense material can be breathable if air holes are formed by processing or the like.

[0012] The porous ceramic body 1 may have a porosity of 10% or more and 50% or less, for example. The porous ceramic body 1 may have an average pore diameter of 20 μm or more and 100 μm or less. The porous ceramic body 1 may have an average particle diameter of 50 μm or more and 300 μm or less. When the porosity and pore diameter of the porous ceramic body 1 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.

[0013] The porosity and pore diameter values ​​can be determined, for example, by cutting the measurement target member to an appropriate size and subjecting it to mercury intrusion porosimetry in accordance with JIS R 1655-2003. Alternatively, the porosity and pore diameter values ​​can be determined by observing an arbitrary cross section of the measurement target member using an electron microscope or optical microscope and processing the observed image. The porosity of a porous body can be measured by mercury intrusion porosimetry. The porosity of a dense body can be measured by cross-sectional observation.

[0014] 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.

[0015] Select an average area from the observed surface. For example, select an area of ​​1.06 × 10 ６ μm ２ An image of the area (1190 μm in horizontal direction and 890 μm in vertical direction) is taken with a scanning electron microscope to obtain an observation image at 100x magnification. This observation image is used as the subject for particle analysis using the 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.

[0016] 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 is dark, and the area for removing small figures is 1 μm ２ The noise reduction filter should be enabled. The threshold value should be adjusted according to the brightness of the observed image. The brightness should be dark, the binarization method should be manual, and the small figure removal area should be 1 μm. ２ The threshold may be adjusted so that the markers appearing in the observed image match the shape of the closed pores, with the noise reduction filter being used.

[0017] 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 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.

[0018] The shape and size of the porous ceramic body 1 are not limited and are appropriately determined depending on the application of the resulting adsorption member 10 or the shape of the object to be placed on it. 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.

[0019] 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 range. When the porous ceramic body 1 has a polygonal shape, the length of one side may be, for example, 50 mm or more and 500 mm or less. The porous ceramic body 1 may be, for example, plate-shaped or columnar. The porous ceramic body 1 may have a thickness of 10 mm or more and 50 mm or less.

[0020] As shown in FIG. 1 , the ceramic porous body 1 has an annular second surface 12 surrounding the first surface 11. The second surface 12 is located at a different height from the first surface 11. Specifically, the second surface 12 is located closer to the support portion 2 than the first surface 11. When the second surface 12 is located closer to the support portion 2 than the first surface 11, the first film 31 and the second film 32 overlapping on the second surface 12 can be sufficiently thick. As a result, one of the films is not too thin, and excellent conductivity is achieved between the first film 31 and the second film 32. Because the first surface 11 and the second surface 12 are located at different heights, the first side surface 1a is located between the first surface 11 and the second surface 12. The distance from the first surface 11 to the second surface 12, i.e., the height of the first side surface 1a, is not limited and may be, for example, 300 μm or more and 1000 μm or less.

[0021] The support part 2 is a member that supports 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 material of the support part 2 are also not limited, and may be, for example, porous ceramic or dense ceramic. The support part 2 may be made of a ceramic having the same main component as the porous ceramic body 1. If the main component of the support part 2 is the same ceramic as the main component of the porous ceramic body 1, the difference in thermal expansion coefficient is small. Therefore, an adsorption member 10 whose main component is the same ceramic as the main component of the porous ceramic body 1 will undergo less deformation when heat is applied.

[0022] As shown in Fig. 1, the first film 31 is positioned so as to cover the area from the first surface 11 of the ceramic porous body 1 to the outer surface of the support part 2. In Fig. 1, the first film 31 is positioned up to the outer surface of the support part 2, but the first film 31 may be positioned from the first surface 11 to the second surface 12 of the ceramic porous body 1. The first film 31 is electrically conductive. In this specification, "electrically conductive" means a material having a resistance of 1 x 10 １１ This means that the resistance is Ω or less. Furthermore, the first film 31 may be breathable. If the first film 31 is breathable, an object placed on the first surface 11 of the ceramic porous body 1 is more likely to be adsorbed onto the first surface 11 when the object is sucked through the suction holes 4.

[0023] 1, the second film 32 is positioned so as to cover the first film 31 positioned on the first side surface 1a and the second surface 12. The second film 32 may have a lower resistance than the first film 31.

[0024] The second film 32 covers the first film 31 located on the first side surface 1a and the second surface 12, ensuring sufficient conductivity between the conductive first film 31 and the second film 32, which has a lower resistance than the first film 31. As a result, generated static electricity is efficiently removed, reducing the occurrence of sparks due to sudden discharge. Furthermore, the contact between the first film 31 and the second film 32 located on the first side surface 1a increases the contact area between the first film 31 and the second film 32. Therefore, the adsorption member 10 according to this embodiment reduces peeling between the first film 31 and the second film 32. Furthermore, as shown in FIG. 1 , the second film 32 may further cover the second side surface 1b, which is the outer surface of the ceramic porous body 1, and the outer surface of the support 2. This ensures sufficient conductivity between the conductive first film 31 and the second film 32, which has a lower resistance than the first film 31. As a result, generated static electricity is efficiently removed, reducing the occurrence of sparks due to sudden discharge.

[0025] The material of the first film 31 may be any conductive film. The first film 31 may be, for example, a film formed of ceramic, resin, or the like. Among these, the first film 31 may be a film formed of ceramic. A film formed of ceramic 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 of ceramic has good processing accuracy, making it easy to obtain an adsorption surface with good flatness. Examples of films formed of ceramic include films whose main components are alumina, titanium oxide, zinc oxide, silicon carbide, diamond-like carbon, silicon nitride, boron nitride, and aluminum nitride.

[0026] The first film 31 may have the same main component as the porous ceramic body 1. When the main component of the first film 31 is the same as the main component of the porous ceramic body 1, the difference in thermal expansion (deformation and stress due to temperature changes) can be reduced. If the porous ceramic body 1 is mainly composed of alumina, the first film 31 may be formed of a ceramic containing alumina as the main component and at least one of titanium oxide and zinc oxide.

[0027] The resistivity of the first film 31 can be adjusted by the content of titanium oxide and zinc oxide relative to alumina. The first film 31 has a lower resistance as the content of titanium oxide and zinc oxide increases. ５ Ω or more 1×10 １０ The first film 31 may have a resistance value of Ω or less. The contents of titanium oxide and zinc oxide in the first film 31 may be adjusted so that the resistance value falls within this range.

[0028] When the first film 31 is made of ceramic, the first film 31 may be a ceramic sprayed film. Film formation by spraying can be performed at a relatively low temperature. Film formation by spraying has little thermal stress, and it is relatively easy to make the film thick. Film formation by spraying can also leave a uniform film even if the surface after film formation is flattened. Examples of ceramic films that can be formed by spraying include alumina, titanium oxide, and zinc oxide. The first film 31 may be porous or dense, as long as it has a thickness that does not block the communicating pores opening to the first surface 11 of the ceramic porous body 1. The first film 31 may have a thickness of, for example, 10 μm or more and 200 μm or less.

[0029] When the ceramic porous body 1 is made of a ceramic containing alumina as a main component and the first film 31 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, and therefore the adsorption member 10 according to this embodiment has small thermal stress and higher processing accuracy such as flatness.

[0030] The material of the second film 32 is not limited as long as it has a lower resistance than the first film 31. The second film 32 may be made of, for example, ceramic, resin, or metal. Among these, the second film 32 may be made of ceramic. Examples of ceramic films include films made from titanium oxide, zinc oxide, lead oxide, alumina, and diamond-like carbon. In particular, the second film 32 may be made of ceramic containing titanium oxide as a primary component. When the second film 32 is made of ceramic containing titanium oxide as a primary component, it has high conductivity and can easily remove generated static electricity. The resistance of the second film 32 may be, for example, 20 Ω or less.

[0031] When the main component of the first film 31 and the main component of the second film 32 are both alumina, it is preferable to adjust the content of a component added for, for example, conductivity control so that it is higher in the second film 32 than in the first film 31. When the main component of the first film 31 and the main component of the second film 32 are both diamond-like carbon, it is preferable to make the second film 32 a film having, for example, a higher ratio of SP2 bonds than the first film 31.

[0032] When the second film 32 is made of ceramic, the second film 32 may be a ceramic sprayed film. The second film 32 may be denser and thicker than the first film 31. When the second film 32 is denser and thicker than the first film 31, the conductivity is higher. As a result, generated static electricity is more quickly removed. The second film 32 may be porous or dense. If the second film 32 is porous, the adsorption area can be adjusted by providing breathability. Furthermore, if the second film 32 is dense, the conductivity can be increased. The second film 32 may have a thickness of, for example, 100 μm or more and 2 mm or less. The second film 32 may have a closed porosity of, for example, 10 area% or less.

[0033] The colors of the first film 31 and the second film 32 are not limited and may be, for example, achromatic colors such as white, black, and gray. The colors of the first film 31 and the second film 32 may be, for example, chromatic colors. The first film 31 and the second film 32 may have the same color or different colors. For example, if the first film 31 and the second film 32 have different colors, the outline of the first film 31 becomes clear. As a result, when an object is placed on the placement surface (first surface 11), it can be placed only on the first film 31 or can be placed so that it also overlaps the second film 32.

[0034] For example, when the first film 31 is formed of a ceramic containing alumina and titanium oxide, the color and resistivity of the first film 31 can be adjusted by adjusting the content of titanium oxide and zinc oxide. For example, by including titanium oxide in a ratio of 30% by mass or more and 50% by mass or less, a blackish, conductive first film 31 is formed. For example, when a white-colored object is placed on the first surface 11 on which the blackish first film 31 is formed, the outline of the object can be clearly defined. On the other hand, by including zinc oxide in a ratio of 30% by mass or more and 50% by mass or less, a whiteish, conductive first film 31 is formed. For example, when a black-colored object is placed on the first surface 11 on which the whiteish first film 31 is formed, the outline of the object can be clearly defined.

[0035] Both titanium oxide and zinc oxide impart electrical conductivity to alumina. Therefore, by including titanium oxide and / or zinc oxide in the first film 31 in the above-described proportions, spark generation can be more efficiently reduced. When titanium oxide and zinc oxide are contained in a total content of 30% by mass or more and 50% by mass or less, a grayish, electrically conductive first film 31 is formed. For example, the outline of an object placed on the first surface 11 on which the grayish first film 31 is formed can be clearly defined, regardless of whether the object is black or white.

[0036] The second film 32 located on the second surface 12 may be flush with the first film 31 located on the first surface 11. Alternatively, the second film 32 located on the second surface 12 may be located at a lower level than the first film 31 located on the first surface 11. When the second film 32 located on the second surface 12 is flush with the first film 31 located on the first surface 11, high flatness can be achieved by lapping. On the other hand, when the second film 32 located on the second surface 12 is located at a lower level than the first film 31 located on the first surface 11, an object placed on the first surface 11 is less likely to come into contact with the second film 32. As a result, the suction member 10 according to this embodiment more efficiently reduces the generation of sparks.

[0037] In the adsorption member 10 according to this embodiment, the first side surface 1a located between the first surface 11 and the second surface 12 may be substantially perpendicular to the first surface 11 and the second surface 12, as shown in FIG. 1 . Alternatively, the first side surface 1a may be inclined outward from the first surface 11 to the second surface 12, as shown in FIG. 2 . FIG. 2 is an enlarged explanatory view illustrating another example of the region X shown in FIG. 1 . As shown in FIG. 2 , when the first side surface 1a is inclined outward from the first surface 11 to the second surface 12, the first film 31 bends gently rather than perpendicularly. Therefore, the adsorption member 10 having the first side surface 1a shown in FIG. 2 further reduces breakage of the first film 31. Furthermore, the adsorption member 10 having the first side surface 1a shown in FIG. 2 also reduces peeling of the first film 31.

[0038] A first corner 51 formed by the first surface 11 and the first side surface 1a may be a substantially right angle as shown in FIG. 1 . Alternatively, the first corner 51 may be chamfered as shown in FIG. 2 . When the first corner 51 is chamfered, the first film 31 bends gently rather than perpendicularly. Therefore, the suction member 10 having the first corner 51 shown in FIG. 2 further reduces breakage of the first film 31. Furthermore, the suction member 10 having the first corner 51 shown in FIG. 2 also reduces peeling of the first film 31. In this specification, "substantially perpendicular" and "substantially right angle" refer to a range of 90°±3°.

[0039] A second corner 52 formed by the second surface 12 and the second side surface 1b, which is the outer surface of the ceramic porous body 1, may be approximately right-angled as shown in FIG. 1 . Alternatively, the second corner 52 may be chamfered as shown in FIG. 2 . In particular, when the second corner 52 is chamfered, at least one of the first film 31 and the second film 32 bends gently at the second corner 52 rather than bending perpendicularly. This further reduces breakage of at least one of the first film 31 and the second film 32. Furthermore, peeling of at least one of the first film 31 and the second film 32 is also reduced. The phrase "at least one of the first film 31 and the second film 32" is used because if the first film 31 is not located on the second side surface 1b, the second film 32 may be located on the second side surface 1b.

[0040] As shown in FIG. 1 , the second surface 12 may be substantially horizontal with respect to the first surface 11. Alternatively, as shown in FIG. 2 , the second surface 12 may be inclined outward relative to the first surface 11. The second surface 12 may be inclined downward toward the peripheral edge of the porous ceramic body 1. When the second surface 12 is inclined downward toward the peripheral edge of the porous ceramic body 1, the total thickness of the first film 31 and the second film 32 increases toward the outer periphery (second side surface 1b). As a result, peeling of the first film 31 from the second side surface 1b side can be reduced. Furthermore, when the second surface 12 is inclined downward toward the peripheral edge of the porous ceramic body 1, bending of the first film 31 is also gentler, further reducing breakage of the first film 31. Furthermore, when the second surface 12 is inclined downward toward the peripheral edge of the porous ceramic body 1, peeling of the first film 31 is also reduced. In this specification, "substantially horizontal" includes not only horizontal but also an inclination of 3 degrees or less relative to horizontal.

[0041] A mixed region in which components of the first film 31 and the second film 32 are mixed may be located in a portion near the boundary between the first film 31 and the second film 32. The presence of the mixed region reduces peeling between the first film 31 and the second film 32. For example, the mixed region may be located offset from the vicinity of the boundary toward the first surface 11 (the first film 31 side). In this specification, "near the boundary" refers to a region having a width of 5 mm centered on the boundary between each film that can be seen in a plan view. Specifically, the vicinity of the boundary between the first film 31 and the second film 32 refers to a region ranging from the boundary between the first film 31 and the second film 32, extending 2.5 mm toward the first film 31 and 2.5 mm toward the second film 32.

[0042] Next, an adsorption member according to another embodiment of the present disclosure will be described with reference to Figures 3 and 4. Figure 3 is a cross-sectional view showing an example of an adsorption member 20 according to another embodiment of the present disclosure. As shown in Figure 3, the adsorption member 20 according to this embodiment includes a ceramic porous body 1, a support portion 2, a first film 31, a second film 32, and a third film 33. Note that the same components as those in the adsorption member 10 shown in Figures 1 and 2 are denoted by the same reference numerals as those in Figures 1 and 2, and detailed description thereof will be omitted.

[0043] As shown in Fig. 3, the adsorption member 20 according to this embodiment has a ceramic porous body 1 in which a third surface 13 surrounding the first surface 11 is located between a first surface 11 and a second surface 12. On the other hand, the adsorption member 10 shown in Figs. 1 and 2 differs from the adsorption member 20 according to this embodiment in that it does not have such a third surface 13.

[0044] The ceramic porous body 1 included in the adsorption member 20 according to this embodiment has a third surface 13 between the first surface 11 and the second surface 12, surrounding the first surface 11. Detailed descriptions of the raw materials, shape, and size of the ceramic porous body 1 are omitted here. The third surface 13 may be located at the same height as the first surface 11 or at a different height. As shown in FIG. 3 , the third surface 13 may be located closer to the support 2 than the first surface 11. When the third surface 13 is located closer to the support 2 than the first surface 11, the thickness of the second film 32 can be adjusted, thereby adjusting the visibility of each film, for example. For example, when the outline of the third film 33 is clearly defined, an object can be placed on the placement surface (first surface 11) by placing it only on the first film 31 or overlapping the third film 33.

[0045] The third surface 13 may be located closer to the support portion 2 than the first surface 11, so that the third side surface 1c may be located between the first surface 11 and the third surface 13. The distance from the first surface 11 to the third surface 13, i.e., the height of the third side surface 1c, is not limited and may be, for example, 400 μm or more and 1000 μm or less.

[0046] In the ceramic porous body 1 included in the adsorption member 20 according to this embodiment, the second surface 12 may be located closer to the support part 2 than the third surface 13, as shown in Fig. 3. By the second surface 12 being located closer to the support part 2 than the third surface 13, the fourth side surface 1d may be located between the third surface 13 and the second surface 12. The distance from the third surface 13 to the second surface 12, i.e., the height of the fourth side surface 1d, is not limited and may be, for example, 100 µm or more and 500 µm or less.

[0047] As shown in FIG. 3 , when viewed cross-sectionally, the width W12 of the second surface 12 and the width W13 of the third surface 13 are not limited. For example, the width W12 of the second surface 12 and the width W13 of the third surface 13 may be different. In this case, the width W13 of the third surface 13 may be greater than the width W12 of the second surface 12. When the width W13 of the third surface 13 is greater than the width W12 of the second surface 12, the films can be formed with high precision, for example, by thermal spraying. Furthermore, when the second surface 12 is located closer to the support portion 2 than the third surface 13, the thickness T32 of the second film 32 located on the second surface 12 is the thickest. In this case, the thickness T32 of the conductive second film 32 is the thickest, increasing the contact area between the second film 32 and the third film 33 and reducing film peeling. Furthermore, when the thickness T32 of the conductive second film 32 is the thickest, the conductive portion can be increased, reducing the occurrence of sparks. Furthermore, since the thickness T32 of the second film 32 is greater than the thickness T33 of the third film 33, peeling of the second film 32 due to thermal expansion of the third film 33 can be reduced.

[0048] As shown in FIG. 3 , the third film 33 may be positioned to cover the first film 31 located on the third side surface 1c and the third surface 13. As an example of different reflectances, when the reflectance of the first film 31 is 10% or less in the visible light range, the reflectance of the third film 33 may be greater than 10%. Furthermore, due to the different reflectances, the third film 33 may have a different reflectance from that of the first film 31. That is, the third film 33 may have a different color from that of the first film 31. When the third film 33 has a different reflectance from that of the first film 31, the outline of the first film 31 becomes clear. As a result, it becomes easier to adjust the position when placing an object on the placement surface (first surface 11). Furthermore, the reflectance is measured as follows: A spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd.) is placed at a predetermined location and measurements are performed. Light is then emitted and the reflected light at the predetermined location is measured. The reflectance (SCI) including specular reflection and diffuse reflection is measured in 10 nm increments from 360 nm to 710 nm, and the difference in the values ​​is measured between the first film 31 and the third film 33. Here, "different reflectances" means that the reflectances (SCI) for each wavelength are all different.

[0049] Furthermore, the first film 31 may be located on the third surface 13 so as to expose a portion of the third surface 13 rather than covering the entire third surface 13. In this case, the third film 33 may have a portion that is in direct contact with the third surface 13. This makes the thickness of the third film 33 thicker in parts compared to when the first film 31 covers the entire third surface 13, and therefore peeling of the third film 33 is reduced due to, for example, an anchor effect.

[0050] Furthermore, the first film 31 may be positioned on the third side surface 1c so that a portion of the third side surface 1c is exposed, rather than covering the entire third side surface 1c. In this case, the third film 33 may have a portion that is in direct contact with the third side surface 1c. As a result, compared to when the first film 31 covers the entire third side surface 1c, the thickness of the third film 33 is increased only in the portion that is in direct contact, and peeling of the third film 33 is reduced, for example, by an anchor effect.

[0051] The third film 33 is not limited as long as it has a reflectance different from that of the first film 31. Examples of the third film 33 include films formed from ceramic, resin, metal, etc. Among these, the third film 33 may be a film formed from ceramic. Examples of films formed from ceramic include films made from titanium oxide, zinc oxide, lead oxide, alumina, diamond-like carbon, etc.

[0052] The color of the third film 33 may be different from the color of the first film 31. The color of the third film 33 may be, for example, an achromatic color such as white, black, or gray. The color of the third film 33 may be, for example, a chromatic color. For example, the first film 31 and the second film 32 may have the same color, and the third film 33 may have a color different from the first film 31 and the second film 32. As an example of a case where the color of the third film 33 is different from the color of the first film 31, the first film 31 may be black and the third film 33 may be white. When the third film 33 is formed of, for example, a ceramic containing alumina and titanium oxide, the color and resistivity of the third film 33 can be adjusted by the content of titanium oxide and zinc oxide, as described above.

[0053] The third film 33 may have a higher resistance than the first film 31. When the third film 33 has a higher resistance than the first film 31, sparks due to sudden discharge caused by contact when placing an object on the placement surface (first surface 11) are reduced. The third film 33 has a resistance of, for example, 1×10 １０ It may have a resistance of Ω or more.

[0054] In the adsorption member 20 according to this embodiment, the third side surface 1c located between the first surface 11 and the third surface 13 may be substantially perpendicular to the first surface 11 and the third surface 13, as shown in FIG. 3 . Furthermore, the third side surface 1c may be inclined outward from the first surface 11 to the third surface 13, as shown in FIG. 4 . FIG. 4 is an enlarged explanatory view illustrating another example of the region Y shown in FIG. 3 . Furthermore, the fourth side surface 1d located between the third surface 13 and the second surface 12 may be substantially perpendicular to the third surface 13 and the second surface 12, as shown in FIG. 3 . Furthermore, the fourth side surface 1d may be inclined outward from the third surface 13 to the second surface 12, as shown in FIG. 4 . When at least one of the third side surface 1c and the fourth side surface 1d is inclined outward as described above, the first film 31 bends gently rather than perpendicularly. Therefore, when at least one of the third side surface 1c and the fourth side surface 1d is inclined outward, breakage of the first film 31 is further reduced. Furthermore, when at least one of the third side surface 1c and the fourth side surface 1d is inclined outward, peeling of the first film 31 is also reduced.

[0055] The third corner 53 formed by the first surface 11 and the third side surface 1c may be a substantially right angle as shown in FIG. 3 . The third corner 53 may also be chamfered as shown in FIG. 4 . The fourth corner 54 formed by the third surface 13 and the fourth side surface 1d may be a substantially right angle as shown in FIG. 3 . The fourth corner 54 may also be chamfered as shown in FIG. 4 . The second corner 52 is as described above, and a detailed description thereof will be omitted. When at least one of the second corner 52, the third corner 53, and the fourth corner 54 is chamfered, the first film 31 bends gently rather than vertically. Therefore, when at least one of the second corner 52, the third corner 53, and the fourth corner 54 is chamfered, breakage of the first film 31 is further reduced. Furthermore, when at least one of the second corner 52, the third corner 53, and the fourth corner 54 is chamfered, peeling of the first film 31 is also reduced.

[0056] The third surface 13 may be substantially parallel to the first surface 11, as shown in FIG. 3 . Alternatively, the third surface 13 may be inclined downward toward the outside, as shown in FIG. 4 . The third surface 13 may be inclined downward toward the peripheral edge of the ceramic porous body 1. The second surface 12 is as described above, and a detailed description thereof will be omitted. When at least one of the second surface 12 and the third surface 13 is inclined downward toward the peripheral edge of the ceramic porous body 1, the total thickness of the first film 31 and the second film 32 and the total thickness of the first film 31 and the third film 33 increase toward the outer periphery (second side surface 1b). As a result, peeling of the first film 31 from the second side surface 1b side can be reduced. Furthermore, bending of the first film 31 is also gentler, further reducing breakage of the first film 31. Furthermore, if at least one of the second surface 12 and the third surface 13 is inclined downward toward the peripheral edge of the porous ceramic body 1, peeling of the first film 31 is also reduced.

[0057] 5 is an enlarged view illustrating another example of region Y shown in FIG. 3 . As shown in FIG. 5 , a first region 331 in which components of the first film 31 and the third film 33 are mixed may be located in a portion near the boundary between the first film 31 and the third film 33. Furthermore, a second region 332 in which components of the second film 32 and the third film 33 are mixed may be located in a portion near the boundary between the second film 32 and the third film 33. At least one of the first region 331 and the second region 332 may be located. When the first region 331 is located in a portion near the boundary between the first film 31 and the third film 33, peeling between the first film 31 and the third film 33 is reduced. When the second region 332 is located in a portion near the boundary between the second film 32 and the third film 33, peeling between the second film 32 and the third film 33 is reduced. As described above, the term "near the boundary" in this specification refers to a 5 mm-wide region centered on the boundary between each film that can be seen in a plan view. Specifically, the term "near the boundary between the first film 31 and the third film 33" refers to a region ranging from the boundary between the first film 31 and the third film 33 to 2.5 mm in the direction toward the first film 31 and 2.5 mm in the direction toward the third film 33. The term "near the boundary between the second film 32 and the third film 33" refers to a region ranging from the boundary between the second film 32 and the third film 33 to 2.5 mm in the direction toward the second film 32 and 2.5 mm in the direction toward the third film 33. For example, as shown in FIG. 5 , the first region 331 may be positioned offset toward the first surface 11 (the first film 31 side) from the vicinity of the boundary between the first film 31 and the third film 33. The second region 332 may be located offset from the vicinity of the boundary between the second film 32 and the third film 33 toward the third surface 13 side (the third film 33 side).

[0058] 3, the third surface 13 is connected to the first surface 11 via the third side surface 1c and to the second surface 12 via the fourth side surface 1d. However, the third surface 13 does not have to be connected to the first surface 11 and the second surface 12 in this manner, as long as it is located between the first surface 11 and the second surface 12.

[0059] As shown in Figures 1 and 3, the adsorption members 10, 20 may have suction holes 4 formed therein. The suction holes 4 have openings on the surface of the adsorption members 10, 20 opposite the first surface 11 on which an object is placed, and may extend all the way to the underside of the porous ceramic body 1. The suction holes 4 may be connected to a suction source (not shown), such as a vacuum pump. When the suction source is activated, the suction holes 4 become a path for sucking air, and the object is adsorbed and held via the porous ceramic body 1 (first surface 11). If the support portion 2 is porous and has sufficient breathability, the suction holes 4 may be omitted.

[0060] Next, a method for manufacturing the adsorption member 10 according to the embodiment will be described. The method for manufacturing the adsorption member 10 includes, for example, the following steps (a) to (f): (a) preparing a porous ceramic having an upper surface, a lower surface, and a side surface, and a support; (b) forming a first surface and an annular second surface located at a different height from the first surface and surrounding the first surface on the upper surface of the porous ceramic to obtain a porous ceramic body; (c) fixing the porous ceramic body to the support; (d) forming a conductive first film extending from the first surface to the second surface; (e) forming a second film having a lower resistance than the first film on the surface of the first film located on the first side surface and the second surface; and (f) simultaneously grinding the first film and the second film to make the first film and the second film approximately flush with each other.

[0061] Step (a) is a step of preparing a porous ceramic having an upper surface, a lower surface, and a side surface, and a support part 2. The porous ceramic will eventually become the porous ceramic body 1. Therefore, the ceramic forming the porous ceramic 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 manufacturing the porous ceramic body 1 containing alumina as a main component will be described below.

[0062] First, aluminum oxide powder having an average particle size D50 of 50 μm or more and 250 μm or less, glass powder having an average particle size D50 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 the aluminum oxide powder may be 5 parts by mass or more and 10 parts by mass or less. The glass powder becomes a glass component that binds the aluminum oxide crystal particles that form the porous ceramic by heat treatment described below. The softening point of the glass powder may be 750°C or more and 940°C or less. The ratio of water may be 5 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the total of the aluminum oxide powder and the glass powder. Other polar solvents may be used instead of water.

[0063] 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.

[0064] Next, the obtained granules are filled into a mold and pressed and 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 porous ceramic.

[0065] As described above, the support part 2 may be made of porous ceramic or dense ceramic. For example, in the case of porous ceramic, the porous ceramic that will become the support part 2 may be formed using the same procedure as described above.

[0066] Step (b) is a step of forming a first surface 11 and an annular second surface 12 that is located at a different height from the first surface 11 and surrounds the first surface 11 on the upper surface of the porous ceramic obtained in step (a), thereby obtaining a porous ceramic body 1. The second surface 12 may be formed at a lower position than the first surface 11, as shown in Fig. 1. Specifically, the second surface 12 may be formed by removing the peripheral portion of the upper surface of the porous ceramic by cutting or grinding. In this manner, the porous ceramic body 1 is formed.

[0067] As shown in Fig. 2, when forming the second surface 12, the first side surface 1a may be machined to be inclined outward as necessary. The second surface 12 may be machined to be inclined so as to be lower toward the outside. Furthermore, a first corner 51 formed by the first surface 11 and the first side surface 1a may be chamfered. A second corner 52 formed by the second surface 12 and the second side surface 1b may be chamfered.

[0068] Step (c) is a step of fixing the porous ceramic body 1 obtained in step (b) to the support part 2. The method of fixing the porous ceramic body 1 to the support part 2 is not limited. For example, the porous ceramic body 1 may be fixed to the support part 2 via an adhesive layer between the porous ceramic body 1 and the support part 2, or the porous ceramic body 1 may be fixed to the support part 2 by diffusion bonding.

[0069] Step (d) is a step of forming a conductive first film 31 from the first surface 11 to the second surface 12. The first film 31 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 31 containing alumina and titanium oxide.

[0070] 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 31) on the surface of the ceramic porous body 1. The mixing ratio of alumina and titanium oxide is adjusted so that the first film 31 has the desired color (brightness) and resistance value. Areas of the surface of the ceramic porous body 1 where the first film 31 is not to be formed may be covered with a mask. As shown in FIG. 1 , the first film 31 may extend to the side surface of the support 2.

[0071] Step (e) is a step of forming a second film 32 having a lower resistance than the first film 31 on the surface of the first film 31 located on the first side surface 1 a and the second surface 12. The second film 32 is as described above, and a detailed description thereof will be omitted. When the second film 32 contains titanium oxide as a main component, for example, the second film 32 can be formed by employing a plasma spraying method in accordance with the method for forming the first film 31, and using a spray powder containing titanium oxide as a main component.

[0072] In step (f), the first film 31 and the second film 32 are simultaneously ground to make the first film 31 and the second film 32 approximately flush with each other. In steps (d) and (e), the first film 31 and the second film 32 are formed to be slightly thicker than the desired thickness, and in step (f), the first film 31 and the second film 32 are ground together by, for example, at least one of surface grinding and lapping to make the first film 31 and the second film 32 approximately flush with each other.

[0073] By carrying out these steps (a) to (f), the adsorption member 10 shown in FIG. 1 is obtained.

[0074] Next, a method for manufacturing the adsorption member 20 according to the embodiment will be described. The method for manufacturing the adsorption member 20 includes, for example, the following steps (A) to (G): (A) preparing a porous ceramic having an upper surface, a lower surface, and a side surface, and a support; (B) forming a first surface, an annular second surface located at a different height from the first surface and surrounding the first surface, and an annular third surface located between the first and second surfaces and surrounding the first surface, on the upper surface of the porous ceramic, to obtain a porous ceramic body; (C) fixing the porous ceramic body to the support; (D) forming a conductive first film extending from the first surface to the second surface; (E) forming a third film having a reflectivity different from that of the first film on a third side surface and on the surface of the first film located on the third surface; and (F) forming a second film having a lower resistance than the first film on a fourth side surface and on the surface of the first film located on the second surface. (G) A step of simultaneously grinding the first film, the second film, and the third film to make the first film, the second film, and the third film substantially flush with each other.

[0075] Step (A) is the same as step (a) described above, and a detailed description thereof will be omitted. Step (B) is a step of forming a third surface 13 in addition to step (b) described above. As shown in FIG. 3 , the third surface 13 may be formed so as to be located at a height between the first surface 11 and the second surface 12. The second surface 12 and the third surface 13 may be formed to have the same width, or may be formed to have different widths. When the second surface 12 and the third surface 13 are formed to have different widths, the width of the third surface 13 may be formed to be larger than the width of the second surface 12.

[0076] As shown in FIG. 4 , when forming the second surface 12 and the third surface 13, the third side surface 1c may be machined to be inclined outward as necessary. The fourth side surface 1d may be machined to be inclined outward. The second surface 12 may be machined to be inclined so as to be lowered outward. The third surface 13 may be machined to be inclined so as to be lowered outward. Furthermore, a third corner 53 formed by the first surface 11 and the third side surface 1c may be chamfered. A fourth corner 54 formed by the third surface 13 and the fourth side surface 1d may be chamfered. A second corner 52 formed by the second surface 12 and the second side surface 1b may be chamfered.

[0077] Steps (C) and (D) are the same as steps (c) and (d) described above, and detailed description thereof will be omitted. Step (E) is a step of forming a third film 33 having a reflectivity different from that of the first film 31 on the surface of the first film 31 located on the third side surface 1c and the third face 13. The third film 33 is as described above, and detailed description thereof will be omitted. When the third film 33 contains alumina as a main component, for example, the third film 33 can be formed by adopting a plasma spraying method in accordance with the film formation method for the first film 31, and by using a spray powder containing alumina as a main component.

[0078] Step (F) is the same as step (e) described above, and a detailed description thereof will be omitted. Step (G) is a step of simultaneously grinding the first film 31, the second film 32, and the third film 33 to make them approximately flush with each other. In steps (D) to (F), the first film 31 and the second film 32 are formed to be slightly thicker than the desired thickness, and in step (G), the first film 31, the second film 32, and the third film 33 are ground together by, for example, at least one of surface grinding and lapping, to make them approximately flush with each other.

[0079] By performing these steps (A) to (G), an adsorption member 20 according to another embodiment is obtained as shown in Fig. 3 and Fig. 6. Fig. 6 is a perspective view of the adsorption member 20 shown in Fig. 3. The obtained adsorption member 10 according to one embodiment and the adsorption member 20 according to another embodiment are used as components of a processing device that fixes an object such as a semiconductor wafer and processes the surface of the object.

[0080] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various modifications and improvements are possible within the scope of the present disclosure.

[0081] In one embodiment, (1) the adsorption member includes a ceramic porous body having a first surface including a mounting surface, a ring-shaped second surface located at a different height from the first surface and surrounding the first surface, and a first side surface located between the first surface and the second surface, and having pores communicating in the thickness direction; a support portion supporting the ceramic porous body; a first film having electrical conductivity; and a second film having lower resistance than the first film, wherein the first film covers the first surface, the first side surface, and the second surface, and the second film covers the first film located on the first side surface and the second surface.

[0082] The present disclosure further discloses the following embodiments (2) to (8).

[0083] (2) The adsorption member described in (1) above may have a ring-shaped third surface located between the first surface and the second surface and surrounding the first surface, and a third film having a reflectance different from that of the first film may be provided on the third surface. (3) The adsorption member described in (2) above may have a height of the third surface lower than that of the first surface. (4) The adsorption member described in (2) or (3) above may have a third film having a higher resistance than the first film. (5) The adsorption member described in any one of (2) to (4) above may have a third side surface located between the first surface and the third surface and a fourth side surface located between the third surface and the second surface, and at least one of a second corner formed by the second surface and the second side surface, which is the outer surface of the ceramic porous body, a third corner formed by the first surface and the third side surface, and a fourth corner formed by the third surface and the fourth side surface may be chamfered. (6) In the adsorption member according to any one of (2) to (5) above, at least one of a first region containing a mixture of components of the first film and components of the third film may be located in a portion near the boundary between the first film and the third film, and a second region containing a mixture of components of the second film and components of the third film may be located in a portion near the boundary between the second film and the third film. (7) In the adsorption member according to any one of (2) to (6) above, at least one of the second surface and the third surface may be inclined so as to decrease in size toward the periphery of the porous ceramic body. (8) In the adsorption member according to any one of (1) to (7) above, the second film may further cover the outer surface of the porous ceramic body and the outer surface of the support.

[0084] The disclosed embodiments should be considered in all respects as illustrative and not restrictive. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0085] REFERENCE SIGNS LIST 1 ceramic porous body 11 first surface 12 second surface 13 third surface 1a first side surface 1b second side surface 1c third side surface 1d fourth side surface 2 support portion 31 first membrane 32 second membrane 33 third membrane 331 first region 332 second region 4 suction hole 51 first corner portion 52 second corner portion 53 third corner portion 54 fourth corner portion 10, 20 adsorption member

Claims

1. An adsorption member comprising: a ceramic porous body having a first surface including a mounting surface, a ring-shaped second surface located at a different height from the first surface and surrounding the first surface, and a first side surface located between the first surface and the second surface, the ceramic porous body having pores communicating in the thickness direction; a support part supporting the ceramic porous body; a first film having electrical conductivity; and a second film having a lower resistance than the first film, wherein the first film covers the first surface, the first side surface, and the second surface, and the second film covers the first film located on the first side surface and the second surface.

2. The adsorption member according to claim 1, which is located between said first surface and said second surface, has an annular third surface surrounding said first surface, and has a third film on said third surface having a reflectance different from that of said first film.

3. The suction member according to claim 2, wherein the height of the third surface is lower than the height of the first surface.

4. The adsorption member according to claim 2 or 3, wherein the third film has a higher resistance than the first film.

5. An adsorption member according to any one of claims 2 to 4, having a third side face located between the first face and the third face, and a fourth side face located between the third face and the second face, wherein at least one of a second corner formed by the second face and the second side face, which is the outer face of the ceramic porous body, a third corner formed by the first face and the third side face, and a fourth corner formed by the third face and the fourth side face, is chamfered.

6. An adsorption member described in any one of claims 2 to 5, wherein at least one of a first region in which components of the first film and components of the third film are mixed is located in a portion near the boundary between the first film and the third film, and a second region in which components of the second film and components of the third film are mixed is located in a portion near the boundary between the second film and the third film.

7. The adsorption member according to any one of claims 2 to 6, wherein at least one of the second surface and the third surface is inclined downward toward the peripheral edge of the porous ceramic body.

8. The adsorption member according to any one of claims 1 to 7, wherein the second film further covers the outer surface of the porous ceramic body and the outer surface of the support portion.

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