JP2019009418A - Substrate holding member - Google Patents

Abstract

To provide a substrate holding member capable of holding a substrate with good flatness for a long period of time.SOLUTION: A substrate holding member 1 includes a base 10 and a plurality of convex portions 20 formed on the upper surface of the base 10 and holding a substrate on a top surface 20a. Each of the convex portions 20 has a root portion 21 extending from the upper surface of the base 10 and a top portion 22 formed on the root portion 21 and including the top surface 20a. In the convex portion 20, a cross-sectional area S1 of the root portion 21 is larger than a cross-sectional area S2 of the top portion 22, and at least a part including the top surface 20a of the top portion 22 includes a holding member 30 made of a material having a Young's modulus greater than that of the material forming the base 10, and the holding members 30 are separated from each other.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a substrate holding member, particularly a substrate holding member such as a vacuum chuck for holding a substrate such as a wafer.

  In a semiconductor manufacturing apparatus, a substrate holding member is used as a member for holding a substrate such as a wafer. Such a substrate holding member has a plurality of convex portions formed on the surface of the base, and holds the wafer on the top surface (tip surface) of the convex portions.

  In order to minimize the contact area between the convex portion and the substrate, it is necessary to reduce the area of the top surface of the convex portion. Moreover, in order to vacuum-suck the substrate, a certain amount of height is required for the convex portion. Accordingly, the convex portion is formed in an elongated cylindrical shape.

  And it has been proposed to form a coating film at the tip of the elongated cylindrical protrusion (see Patent Document 1). In addition, it has also been proposed to form a coating (protective layer) on the entire surface of the base (base) including the protrusions (protrusions), and in this case, the particles are prevented from falling off from the base. There is also an effect (refer to patent documents 2).

Japanese Patent No. 6001675 Japanese Patent No. 50639797

  However, as in Patent Document 1, if the convex portion has an elongated cylindrical shape, the convex portion may be damaged by a sliding force that repeatedly acts on the contact surface between the convex portion and the base, and the substrate may be damaged over a long period of time. It may be difficult to maintain a good flatness.

  On the other hand, when a protective film is formed on the entire surface of the base as in Patent Document 2, peeling or cracking occurs between the base and the protective film when used for a long time due to the difference in physical properties between the base and the protective film. There was a case. This occurs when physical properties such as linear expansion coefficient, elastic modulus, density, hardness, and crystallinity are slightly different, and stress caused by differences in expansion coefficient due to temperature changes, and when wafers are adsorbed and desorbed. This is thought to be due to the stress that occurs. This stress propagates to the substrate below the protective film, causing peeling and cracking. Such peeling or cracking of the protective film may cause generation of particles, and it may be difficult to hold the substrate with good flatness for a long period of time.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a substrate holding member capable of holding a substrate with good flatness for a long period of time.

The substrate holding member of the present invention is a substrate holding member comprising a base and a plurality of convex portions formed on the top surface of the base and holding the substrate on the top surface, wherein the plurality of convex portions are A base portion extending from the top surface of the base and a top portion formed on the base portion and including the top surface, wherein the plurality of convex portions are in the horizontal direction along the top surface of the base. The cross-sectional area of the portion is larger than the cross-sectional area of the top portion in the horizontal direction, and the plurality of convex portions include at least a part including the top surface of the top portion as compared with the material forming the base. The holding member is made of a material having a large thickness, and the holding members constituting the plurality of convex portions are separated from each other.

  According to the substrate holding member of the present invention, at least a part of the convex portion including the top surface in contact with the substrate is made of a holding member formed of a material having a Young's modulus greater than that of the material forming the base. Thereby, compared with the case where a convex part consists of the same material as a base, it becomes possible to improve the abrasion resistance in the top surface which touches a board | substrate, and to suppress that a particle | grain generate | occur | produces from a top surface. .

  And since the cross-sectional area of a convex part is larger than the cross-sectional area of a top part, compared with the convex part (projection part) described in the said patent document 1 with the same whole cross-sectional area, the convex part is the area of a top surface. Even if they are the same, it is possible to increase the rigidity of the convex portion.

  Furthermore, since each holding member is spaced apart from each other, the holding member (coating film) is formed over the entire surface of the base (base) as compared with the case described in Patent Document 2 above. It is possible to suppress peeling and cracking of the film.

  As a result, the substrate can be held with good flatness over a long period of time.

  In the substrate holding member of the present invention, the plurality of convex portions constitutes the root portion extending from the upper surface of the base, and includes a first convex portion having an upper end surface, and an upper portion of the first convex portion. It is preferable that the second protrusion is formed on a part of the end surface and forms the top, and the holding member forms at least a part of the second protrusion.

  In this case, since the first convex portion extends from the upper surface of the base, the first convex portion and the base can be formed integrally. Thereby, the adhesiveness of a 1st convex part and a base can be improved, and it becomes possible to aim at suppression that breakage, such as peeling and generation | occurrence | production of a crack, arises among these.

  In the substrate holding member of the present invention, it is preferable that the holding member constitutes an upper end top portion including the second convex portion and at least the upper end surface of the first convex portion.

  In this case, since the holding member constitutes the second convex portion and the upper end top portion of the first convex portion, it is possible to integrally form them. As a result, it is possible to improve the adhesion between the first convex portion and the second convex portion, and it is possible to suppress the occurrence of breakage such as peeling or generation of cracks between them. .

  In addition, since the holding member constitutes the upper end top portion of the first convex portion, the holding member and the lower portion of the first convex portion are in close contact with each other over a wide area. Therefore, the adhesiveness between the two can be improved, and it is possible to suppress the occurrence of breakage such as peeling or cracking between them.

  Further, in the substrate holding member of the present invention, the plurality of convex portions are formed continuously from the base, and have a portion made of a material forming the base, and made of a material forming the base. It is preferable that a recess is formed in the portion, and that the holding member is formed at least in the recess.

  In this case, since the concave portion is formed in the portion made of the material forming the base of the convex portion, and the holding member is formed in the concave portion, the concave portion is held from the portion made of the material forming the base of the convex portion. It is possible to suppress the peeling of the member.

  In the substrate holding member of the present invention, it is preferable that the holding member constitutes the entirety of the plurality of convex portions.

  In this case, since the holding member constitutes the entire convex portion, it is not necessary to form a continuous portion from the base as a part of the convex portion, so that a process of forming this is unnecessary, and the manufacturing process is simplified. It becomes possible to plan.

  Furthermore, in the substrate holding member of the present invention, it is preferable that a recess is formed on the upper surface of the base, and the holding member is formed at least in the recess.

  In this case, since the concave portion is formed on the upper surface of the base, and the holding member is formed in the concave portion, it is possible to suppress the peeling of the holding member from the base.

1 is a schematic cross-sectional view of a substrate holding member according to a first embodiment of the present invention. The expansion schematic longitudinal cross-sectional view of the convex part of the board | substrate holding member which concerns on the 1st Embodiment of this invention. The expanded sectional photograph of the convex part of the board | substrate holding member which concerns on the 1st Embodiment of this invention. It is an expansion model longitudinal cross-sectional view which shows the manufacturing process of the board | substrate holding member which concerns on the 1st Embodiment of this invention, and shows the state which formed the holding layer in the surface of the base and mounted the mask in the area | region. The expansion schematic longitudinal cross-sectional view of the convex part of the board | substrate holding member which concerns on the 2nd Embodiment of this invention. The expansion schematic longitudinal cross-sectional view of the convex part of the board | substrate holding member which concerns on the 3rd Embodiment of this invention. The expansion schematic longitudinal cross-sectional view of the convex part of the board | substrate holding member which concerns on the 4th Embodiment of this invention. The expansion schematic longitudinal cross-sectional view of the convex part of the board | substrate holding member which concerns on the 5th Embodiment of this invention.

  A substrate holding member 1 according to a first embodiment of the present invention will be described with reference to the drawings.

  As shown in the cross-sectional view of FIG. 1, the substrate holding member 1 is formed on a disk-like base 10 and a plurality of convex portions that are formed on the top surface of the base 10 and hold a wafer (substrate) (not shown) on the top surface 20a. (Protrusions, pins) 20.

  In the substrate holding member 1, as shown in the partial enlarged cross-sectional view of FIG. 2, each convex portion 20 includes a root portion 21 extending from the upper surface of the base 10 and a top surface 20 a formed on the root portion 21. And a top portion 22 including the same. And the convex part 20 has the cross-sectional area S1 of the root part 21 in the horizontal direction (left-right direction in FIG. 2) along the upper surface of the base 10 larger than the cross-sectional area S2 of the top part 22 in the said horizontal direction.

  The convex portion 20 includes a holding member 30 formed of a material having a Young's modulus larger than that of the material forming the base 10 at least partially including the top surface 20 a of the top portion 22. It is preferable that at least a part of the top portion 22 including the top surface 20a is made of a material having a smaller porosity (less pores) than the material forming the base 10. Each holding member 30 is separated from each other.

  In the present embodiment, the convex portion 20 includes a cylindrical lower portion 23 and a cylindrical upper portion 24 that protrudes above the lower portion 23 and has a smaller diameter than the lower portion 23. The lower part 23 protrudes from the surface of the base 10 and is formed integrally with the base 10, and is made of the same material as the base 10. That is, the lower part 23 is formed continuously from the base 10.

  The entire upper portion 24 is constituted by the holding member 30. Thereby, the base part 21 of the convex part 20 is a base part (lower end part) of the lower part 23, and the top part 22 of the convex part 20 is a top part (upper end part) of the upper part 24.

  And the top surface 20a of the convex part 20 which is an upper end surface of the holding member 30 is formed flat. The lower portion 23 corresponds to the first convex portion of the present invention, and the upper portion 24 corresponds to the second convex portion of the present invention.

  The height of the lower portion 23 is preferably 0.15 to 0.35 mm, for example, 0.25 mm. The diameter of the lower portion 23 is preferably 1.0 to 1.5 mm, for example, 1.25 mm. The height of the upper portion 24 is preferably 0.02 to 0.06 mm, for example 0.02 mm. The diameter of the upper portion 24 is preferably 0.02 to 0.2 mm, for example, 0.02 mm.

  In FIGS. 1 and 2, the base 10, the convex portion 20, the holding member 30 and the like are exaggerated without considering the actual shape and dimensional ratio. Therefore, the actual shape and dimensional ratio do not always match. The same applies to FIGS. 4 to 8 described later.

  Moreover, although both the lower part 23 and the upper part 24 were described as being cylindrical, due to factors such as the manufacturing method, the corners are curved, the side surfaces are uneven, and the side surfaces are slanted. It will not be cylindrical.

  Examples of the material for the base 10 and the lower portion 23 include silicon carbide (SiC), alumina (Al2O3), etc., but it is preferable that the base 10 and the lower portion 23 are conductive and have high rigidity in order to prevent circuit breakdown due to static electricity. A silicon carbide (SiC) sintered body is preferred. The porosity of the base 10 and the lower part 23 is preferably as small as possible because it causes particle dusting, and the porosity is 5% or less, more preferably 2% or less.

  From the viewpoint of strength, the base 10 and the lower part 23 preferably have smaller pore diameters, and the base 10 and the lower part 23 have an average pore diameter of 1 to 5 μm. The average pore diameter was obtained by photographing a cross section obtained by enlarging the base 10 and the lower part 23 by a magnification of 2000 using a scanning electron microscope (SEM), and using an intercept method for an arbitrary 30 μm square region of the obtained cross-sectional photograph. What is necessary is just to calculate.

  The Young's modulus (longitudinal elastic modulus) of the base 10 and the lower part 23 is 400 to 440 GPa, more preferably 420 to 440 GPa. Moreover, the Vickers hardness of the base 10 and the lower part 23 is 22-26 GPa (load 0.5kgf).

  Examples of the material of the holding member 30 include silicon carbide (SiC), alumina (Al 2 O 3), and the like. The main component is preferably the same material as the base 10 and the lower portion 23, and is preferably silicon carbide. Since the pores of the holding member 30 include a portion that is in direct contact with a substrate such as a wafer, the number of pores is preferably smaller. The porosity of the holding member 30 is smaller than the porosity of the base 10 and the lower part 23, and is 1% or less, more preferably 0.5% or less. The Young's modulus of the holding member 30 is larger than the Young's modulus of the base 10 and the lower part 23, and is 450-480 GPa, More preferably, it is 460-480 GPa. Here, the Young's modulus of the holding member 30, the base 10 and the lower part 23 can be measured in accordance with ISO 14577, which is a test method using the nanoindentation method. The holding member 30 has a Vickers hardness of 28 to 31 GPa (load 0.5 kgf).

  When the material of the base 10 and the lower part 23 is a silicon carbide sintered body, it is preferable that the holding member 30 is a silicon carbide formed by a thermal CVD (chemical vapor deposition) method. This is because, according to the thermal CVD method, the holding member 30 has very few pores, and no pores are observed in the SEM observation of the cross section enlarged 2000 times that of the holding member 30, and the porosity of the holding member 30 is substantially reduced. This is because the porosity and Young's modulus can be easily set within the above-described ranges, and the thickness of the holding member 30 can be easily increased to about 1 mm.

  FIG. 3 shows a scanning electron microscope of a portion in which a holding member 30 made of SiC is formed by a thermal CVD method on a lower portion 23 obtained by atmospheric pressure sintering of SiC to which B4C and C are added as sintering aid components. It is an expanded sectional photograph using (SEM). The silicon carbide sintered body of the lower portion 23 has constant pores distributed, whereas the holding member 30 made of SiC formed by the thermal CVD method has no pores and the porosity is substantially zero. % Is confirmed. The number of pores and the size of the porosity in the holding member 30, the base 10, and the lower portion 23 can be evaluated by observing an enlarged cross-sectional photograph using an SEM.

  In addition, although the case where the lower part 23 and the upper part 24 were each cylindrical shape was demonstrated, if the cross-sectional area S1 of the root part 21 of a convex part is larger than the cross-sectional area S2 of the top part 22, it will not be limited to this. For example, the lower portion 23 and the upper portion 24 may each have a truncated cone shape, or the lower portion 23 and the upper portion 24 may have a single truncated cone shape as a whole. Moreover, the shape of the lower part 23 and the upper part 24 should just be a thing of the shape which spreads from the top to the bottom, and besides a cylinder shape, a prism, a truncated cone, a truncated pyramid etc. may be sufficient. Further, at least one of the upper part 24 or the lower part 23 may have a shape in which a plurality of columnar shapes, truncated cone shapes, and the like are stacked in the vertical direction.

  In the substrate holding member 1, the wafer is supported by the substrate holding member 1 so as to come into contact with the top surfaces 20 a of the plurality of convex portions 20. Then, for example, although not shown, the air in the space defined by the substrate holding member 1 and the wafer is made by a vacuum suction device such as a vacuum pump (not shown) connected to the vacuum suction path 11 formed on the base 10. By being sucked, the wafer is sucked and held on the substrate holding member 1 by this suction force.

  Next, the manufacturing method of the board | substrate holding member 1 is demonstrated with reference to FIG.

  First, a substantially disk-shaped molded body made of silicon carbide is manufactured, and this molded body is sintered in an Ar gas atmosphere at 1900 to 2100 ° C., thereby manufacturing a substantially disk-shaped silicon carbide sintered body. A carbon-containing material such as B4C or C may be added as a sintering aid component to the silicon carbide powder material.

  Next, the lower surface 23 of the plurality of convex portions 20 is formed by subjecting the upper surface of the silicon carbide sintered body to grinding, blasting, electric discharge machining, grinding wheel machining, high energy beam irradiation machining such as laser beam, and the like. Form.

  Further, for example, the holding layer 40 made of silicon carbide is formed so as to cover the entire upper surface of the base 10 including the surface of the lower portion 23 by a thermal CVD method, a plasma CVD method, an ion plating method, or the like. . The formation of the holding layer 40 is preferably performed by a thermal CVD method, but if the porosity and Young's modulus of the holding layer 40 can be within the range of the holding member 30 described above, the plasma CVD method, ion plating may be used. You may carry out by methods, such as a method. The holding layer 40 thus formed covers the entire upper surface of the base 10 and the entire surface of the lower portion 23.

  Next, a mask M is provided so as to cover the region of the portion to be the upper portion 24, and the holding layer 40 is removed by performing blasting or the like on the region excluding the region covered with the mask M. Note that the holding layer 40 may be removed by grinding, electric discharge machining, grindstone machining, high energy beam irradiation machining such as laser beam, or the like. As a result, the holding layer 40 remains in the portion that becomes the upper portion 24, and the holding member 30 is formed. Further, the top surface of the holding member 30 is polished so that at least the top surface of the convex portion 20 is flat.

  According to the substrate holding member 1 described above, at least a part of the convex portion 20 including the top surface 20a in contact with the wafer has a smaller porosity (less pores) than the material forming the base 10 and The holding member 30 is made of a material having a high Young's modulus. Thereby, compared with the case where the convex part 20 consists of the same material as the base 10, the abrasion resistance in the top surface 20a which contact | connects a wafer improves, and it suppresses generation | occurrence | production of a particle from the top surface 20a. Is possible.

  And since the convex part 20 has the cross-sectional area S1 of the base part 21 larger than the cross-sectional area S2 of the top part 22, the whole cross-sectional area is the elongate cylindrical convex part (protrusion) described in the said patent document 1 and the same. In comparison, even if the area of the top surface 20a is the same, the rigidity of the convex portion 20 can be increased.

  Furthermore, since each holding member 30 is separated from each other, the holding member (coating film) is held as compared with the case described in Patent Document 2 in which the entire surface of the base (base) is formed. It becomes possible to suppress peeling and cracking of the member 30.

  As a result, the wafer can be held with good flatness for a long period of time.

  Furthermore, since the lower part 23 extends from the upper surface of the base 10, the lower part 23 and the base 10 can be integrally formed. Thereby, the adhesiveness of the lower part 23 and the base 10 can be improved, and it is possible to suppress the occurrence of breakage such as peeling or cracking between them.

  Next, a substrate holding member 1A according to a second embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 5, the substrate holding member 1A is different from the substrate holding member 1 described above only in that the holding member 30A is also formed in the recess 23Aa formed on the upper surface of the lower portion 23A. To do.

  Accordingly, the holding member 30A is formed in a shape in which the portion formed in the recess 23Aa of the lower portion 23A and the entire upper portion 24 are integrated. The cross-sectional shape in the vertical direction of the recess 23Aa is not particularly limited, such as a semicircular shape, a semi-elliptical shape, and a rectangular shape, and may be a shape whose inner side is enlarged toward the side as compared with the opening. The recess 23Aa preferably has a depth of 0.01 to 0.2 mm and an opening width of 0.02 to 0.2 mm.

  When such a holding member 30A is formed, the recess 23Aa is formed on the upper surface of the lower portion 23A by performing grinding, blasting, electric discharge machining, grinding wheel processing, high energy beam irradiation, etc. when the lower portion 23A is formed. In this case, the holding layer 40 may be formed.

  According to the substrate holding member 1 </ b> A described above, it is possible to maintain good flatness of the wafer over a long period of time as in the case of the substrate holding member 1 described above.

  Further, a recess 23Aa is formed on the upper surface of the lower part 23A made of a material forming the base 10A of the convex part 20A, and the holding member 30A is formed in the recess 23Aa. It is possible to suppress peeling.

Next, a substrate holding member 1B according to a third embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 6, the substrate holding member 1B is made of the same material as the upper portion 24B in which the upper portion of the lower portion 23B constitutes a part of the holding member 30B, as compared with the substrate holding member 1 described above. The only difference is that.

  Thereby, the holding member 30B is formed in a shape in which the upper portion of the lower portion 23B and the entire upper portion 24B are integrated. The lower part of the lower part 23 </ b> A is formed continuously from the base 10. The thickness of the upper portion of the lower portion 23B of the holding member 30B is preferably 0.01 to 0.2 mm.

  According to the substrate holding member 1B described above, similarly to the substrate holding member 1 described above, the wafer can be held with good flatness for a long period of time.

  Furthermore, since the holding member 30B constitutes the upper end top portions of the upper portion 24B and the lower portion 23B, these can be formed integrally. Thereby, the adhesiveness of the lower part 23B and the upper part 24B can be improved, and it is possible to suppress the occurrence of breakage such as peeling or generation of cracks therebetween.

  Further, since the holding member 30B constitutes the upper end top portion of the lower portion 23B, the holding member 30B and the lower portion of the lower portion 23B are in close contact with each other in an area wider than the cross section of the upper portion 24B. Therefore, the adhesiveness between the two can be improved, and it is possible to suppress the occurrence of breakage such as peeling or cracking between them.

  Next, a substrate holding member 1C according to a fourth embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 7, the substrate holding member 1 </ b> C is different from the substrate holding member 1 described above in that the entire convex portion 20 </ b> C is configured by a holding member 30 </ b> C. And this convex part 20C differs from the convex part 20, and has a truncated cone shape as a whole. Moreover, the shape of the convex part 20C should just be a thing of the shape which spreads from the top to the bottom, and besides a truncated cone shape, a truncated pyramid, the side surface became convex or concave outward. The shape may be similar to a truncated cone having a curved surface.

  The height of the convex portion 20C is preferably 0.15 to 0.35 mm, for example, 0.25 mm. The diameter of the base portion 21C of the convex portion 20C is preferably 0.2 to 1.5 mm, for example, 0.25 mm. The diameter of the top portion 22C of the convex portion 20C is preferably 0.02 to 0.2 mm, for example 0.05 mm.

  Since the holding member 30C does not need to form the lower portion 23 as in the case of manufacturing the substrate holding member 1 described above, the step of forming the lower portion is not necessary, and the manufacturing process can be simplified. It becomes possible.

  Note that the truncated conical holding member 30C is formed by forming the holding layer 40 so as to cover the entire upper surface of the base 10C and removing the holding layer 40 other than the portion to be the holding member 30C. Good. The removal of the holding layer 40 is particularly preferably performed by laser beam processing that does not involve an air flow during processing. In processing involving the flow of powder such as blast processing, a curved surface is formed between the lower portion of the holding member 30C having a truncated cone shape and the base 10C. However, laser beam processing can suppress the formation of such a curved surface.

  According to the substrate holding member 1 </ b> C described above, similarly to the substrate holding member 1 described above, it is possible to hold the wafer with good flatness for a long period of time.

Next, a substrate holding member 1D according to a fifth embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 8, the substrate holding member 1 </ b> D only has a holding member 30 </ b> D formed in the recess 10 </ b> Da formed on the upper surface of the base 10 </ b> D as compared with the substrate holding member 1 </ b> C described above. Is different.

  Thereby, holding member 30D is comprised in the shape which integrated the part formed in recessed part 10Da of base 10D, and convex part 20D. The longitudinal cross-sectional shape of the recess 10DAa is not particularly limited, such as a semicircular shape, a semi-elliptical shape, and a rectangular shape, and may be a shape whose inner side is enlarged to the side as compared with the opening. The recess 10Da preferably has a depth of 0.01 to 0.2 mm and an opening width of 0.02 to 0.2 mm.

  Such a recess 10Da is formed on the upper surface of the base 10D by forming a base 10 having a flat upper surface and then performing grinding, sandblasting, electric discharge processing, grinding wheel processing, high energy beam irradiation processing such as laser beam, or the like. A recess 10Da may be formed on the surface.

  According to the substrate holding member 1D described above, similarly to the substrate holding member 1 described above, it is possible to hold the wafer with good flatness for a long period of time.

  Furthermore, since the holding member 30D is formed in the recess 10Da formed on the upper surface of the base 10D, it is possible to suppress the peeling of the holding member 30D from the base 10D.

  1, 1A, 1B, 1C, 1D ... Substrate holding member, 10, 10A, 10B, 10C, 10D ... Base, 10Da ... Recess, 11 ... Vacuum suction path, 20, 20A, 20B, 20C, 20D ... Projection 20a, 20Aa, 20Ba, 20Ca, 20Da ... top surface, 21, 21A, 21B, 21C, 21D ... root part, 22, 22A, 22B, 22C, 22D ... top part, 23, 23A, 23B ... lower part (first Convex part), 23Aa ... concave part, 24, 24A, 24B ... upper part (second convex part), 30, 30A, 30B, 30C, 30D ... holding member, 40 ... holding layer, M ... mask.

Claims (6)

A substrate holding member comprising a base and a plurality of convex portions formed on the top surface of the base and holding the substrate on the top surface,
The plurality of convex portions have a root portion extending from an upper surface of the base and a top portion formed on the root portion and including the top surface,
The plurality of convex portions have a cross-sectional area of the root portion in the horizontal direction along the upper surface of the base larger than a cross-sectional area of the top portion in the horizontal direction,
The plurality of convex portions are formed of a holding member formed of a material having a Young's modulus that is at least partially including a top surface of the top portion as compared with a material forming the base.
The substrate holding member, wherein the holding members constituting the plurality of convex portions are separated from each other. The plurality of convex portions constitute the base portion extending from the upper surface of the base, and are formed on a first convex portion having an upper end surface and a part of the upper end surface of the first convex portion. And a second convex part constituting the top part,
The substrate holding member according to claim 1, wherein the holding member constitutes at least a part of the second convex portion.   The substrate holding member according to claim 2, wherein the holding member constitutes an upper end top portion including the second convex portion and at least the upper end surface of the first convex portion. The plurality of convex portions are formed continuously from the base and have a portion made of a material forming the base;
The substrate according to any one of claims 1 to 3, wherein a concave portion is formed in a portion made of a material forming the base, and the holding member is formed at least in the concave portion. Holding member.   The substrate holding member according to claim 1, wherein the holding member constitutes the entirety of the plurality of convex portions. A recess is formed on the upper surface of the base,
The substrate holding member according to claim 5, wherein the holding member is formed at least in the recess.