Holding member

Abstract

To suppress leakage of a thermal conductive gas from a clearance between a protrusion and an object while suppressing arcing in the protrusion.SOLUTION: A holding member 10 comprises a body unit 11 having a first surface 11A, and a plurality of protrusions 12 protruding from the first surface 11A. A gas flow path 50 that opens in the first surface 11A is formed in the body unit 11, and the plurality of protrusions 12 include an outside protrusion 13 located on the outer circumferential side of the body unit 11 and a center protrusion 14 located on the center side of the body unit 11. A round corner 12C forming a roundish shape is formed at a corner of each protrusion 12. The radius of curvature of a round corner 12C of the outside protrusion 13 is smaller than the radius of curvature of a round corner 12C of the center protrusion 14, and a protruding dimension D1 of the outside protrusion 13 from the first surface 11A is larger than a protruding dimension D1 of the center protrusion 14 from the first surface 11A.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a holding member.

Background Art

[0002] Conventionally, an electrostatic chuck described in Japanese Patent No. 6341457 (Patent Document 1 below) has been known. This electrostatic chuck includes a ceramic dielectric substrate, a heater plate, and a base plate. The ceramic dielectric substrate has a first main surface on which an object to be processed such as a semiconductor wafer is placed, and a second main surface opposite to the first main surface. On the first main surface side of the ceramic dielectric substrate, convex portions are provided as necessary. Grooves are provided between adjacent convex portions. The grooves communicate with each other.

[0003] A space is formed between the back surface of the object to be processed mounted on the electrostatic chuck and the grooves. An introduction path that penetrates the base plate and the ceramic dielectric substrate is connected to the grooves. When a transfer gas such as helium (He) is introduced from the introduction path in a state where the object to be processed is adsorbed and held, the transfer gas flows into the space provided between the object to be processed and the grooves, and the object to be processed can be directly heated or cooled by the transfer gas.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the above configuration, when the object to be processed is subjected to plasma processing, there is a risk that charges will concentrate on the convex portions. When charges concentrate on the convex portions, arcing (abnormal discharge, dielectric breakdown) may occur at the convex portions. In order to suppress the charge concentration on the convex portions, it is conceivable to form rounded rounded portions at the corners of the convex portions.

[0006] However, when a rounded portion is formed at the corner of the convex portion, the contact area between the back surface of the object to be processed and the upper surface of the convex portion decreases, so that the transfer gas may easily leak from the space between the object to be processed and the groove.

[0007] The present disclosure has been completed based on the above circumstances, and an object thereof is to suppress arcing in the convex portion and suppress leakage of the heat transfer gas from the gap between the convex portion and the object.

Means for Solving the Problems

[0008] The holding member of the present disclosure includes a main body portion having a first surface and a plurality of convex portions protruding from the first surface. A gas flow path opening to the first surface is formed in the main body portion. The plurality of convex portions include outer convex portions arranged on the outer peripheral side of the main body portion and central convex portions arranged on the central side of the main body portion. At the corner of each convex portion, a rounded portion having a rounded shape is formed. The radius of curvature of the rounded portion of the outer convex portion is smaller than the radius of curvature of the rounded portion of the central convex portion, and the protruding dimension of the outer convex portion from the first surface is larger than the protruding dimension of the central convex portion from the first surface.

Advantages of the Invention

[0009] According to the present disclosure, it is possible to suppress arcing in the convex portion and suppress leakage of the heat transfer gas from the gap between the convex portion and the object.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

DETAILED DESCRIPTION OF THE INVENTION

[0011] [Description of Embodiments of the Present Disclosure] First, the embodiments of the present disclosure will be listed and described. (1) The holding member of the present disclosure includes a main body portion having a first surface and a plurality of convex portions protruding from the first surface. A gas flow path that opens to the first surface is formed in the main body portion. The plurality of convex portions include outer convex portions arranged on the outer peripheral side of the main body portion and central convex portions arranged on the central side of the main body portion. At the corner portions of each convex portion, a rounded arcuate portion is formed. The radius of curvature of the arcuate portion of the outer convex portion is smaller than the radius of curvature of the arcuate portion of the central convex portion, and the protruding dimension of the outer convex portion from the first surface is larger than the protruding dimension of the central convex portion from the first surface.

[0012] According to such a configuration, by forming the arcuate portion at the corner portion of the convex portion, it is possible to suppress charge concentration at the corner portion of the convex portion and suppress arcing inside the convex portion.

[0013] In the outer convex portion, the radius of curvature of the arcuate portion is smaller compared to the central convex portion. Therefore, the contact area between the outer convex portion and the object can be increased. Thus, the heat-conductive gas supplied from the gas flow path is less likely to leak between the outer convex portion and the object.

[0014] In the outer convex portion, since the radius of curvature of the arcuate portion is smaller compared to the central convex portion, it is considered that arcing is more likely to occur inside the outer convex portion than in the central convex portion. However, in the outer convex portion, since the protruding dimension from the first surface of the convex portion is large, arcing inside the convex portion can be suppressed.

[0015] (2) In the holding member described in (1), an electrode member is embedded on the first surface side inside the main body portion, the convex portion has a top surface orthogonal to the protruding direction in which the convex portion protrudes from the first surface, and it is preferable that the distance in the protruding direction between the top surface of the outer convex portion and the electrode member is larger than the distance in the protruding direction between the top surface of the central convex portion and the electrode member.

[0016] According to such a configuration, by increasing the distance in the protruding direction between the outer convex portion and the electrode member, it is possible to suppress the occurrence of arcing on the outer periphery of the main body portion.

[0017] (3) In the holding member described in (1) or (2), an electrode member is embedded on the first surface side inside the main body portion, and when viewed from the protruding direction in which the convex portion protrudes from the first surface, it is preferable that the electrode member is not formed at a position overlapping the convex portion.

[0018] According to such a configuration, since the electrode member is not formed at a position overlapping the convex portion of the electrode member in the protruding direction, it is possible to suppress the occurrence of arcing between the convex portion and the electrode member when charge concentration occurs in the convex portion.

[0019] [Details of Embodiment 1 of the Present Disclosure] A specific example of Embodiment 1 of the present disclosure will be described with reference to FIGS. 1 to 4. Note that the present disclosure is not limited to these examples, is shown by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. In the following description, for a plurality of identical members, only some members may be assigned reference numerals, and the reference numerals of other members may be omitted. In this specification, the configuration of the holding member 10 will be described with the positive Z-axis direction being the upward direction, the negative Z-axis direction being the downward direction, and the XY plane direction being the horizontal direction. However, in the actual usage mode of the holding member 10, it may be arranged differently. Also, in this specification, "orthogonal" shall include arrangements in a mode that is substantially recognized as orthogonal.

[0020] <Electrostatic Chuck> The holding device including the holding member 10 of the present disclosure is an electrostatic chuck 1 that can adsorb and hold an object such as a semiconductor wafer or a glass substrate (hereinafter referred to as "wafer W"). The electrostatic chuck 1 is attached to a processing chamber of a semiconductor manufacturing apparatus (not shown), for example, and is used to perform various processes (film formation, etching, etc.) on the wafer W using plasma.

[0021] As shown in FIG. 1, the electrostatic chuck 1 includes a holding member 10 and a base member 20. Note that in FIG. 1, the detailed configuration of the holding member 10 is not shown. The holding member 10 and the base member 20 are joined by a joining portion 30. The joining portion 30 is formed of an adhesive such as a silicone-based resin, an acrylic-based resin, or an epoxy-based resin, for example. The electrostatic chuck 1 is configured to be able to adsorb and hold the wafer W by electrostatic attraction.

[0022] <Base Member> The base member 20 is a disk-shaped member and can be formed into a shape having a diameter of about 340 mm and a thickness of about 35 mm, for example. The material mainly forming the base member 20 is a conductive material such as aluminum or an aluminum alloy. Here, the "material mainly forming" means the main component, that is, the material having the largest content ratio (weight ratio) (the same shall apply hereinafter). As shown in FIG. 2, the upper surface S3 of the base member 20 is disposed on the holding member 10 side. The upper surface S3 of the base member 20 is joined to the lower surface S2 of the holding member 10, which will be described later, by the joining portion 30.

[0023] A refrigerant flow path 21 is provided inside the base member 20. The refrigerant flow path 21 is connected to a refrigerant circulation device (not shown). The refrigerant circulation device is configured to be able to circulate a refrigerant such as a fluorine-based inert liquid or water through the refrigerant flow path 21. When the refrigerant is flowed through the refrigerant flow path 21, the base member 20 is cooled, and the holding member 10 is cooled by heat transfer (heat extraction) between the base member 20 and the holding member 10 via the joining portion 30, and the wafer W held on the holding surface S1 of the holding member 10, which will be described later, is cooled. Thereby, the temperature of the wafer W can be controlled.

[0024] Further, inside the base member 20, a gas injection passage 22 is provided in which the inside is formed such that a fluid can move. The gas injection passage 22 opens to the lower surface S4 of the base member 20 and communicates with a gas passage 50 of a holding member 10 described later through a hole provided in the joint portion 30. A thermally conductive gas is injected from the gas injection passage 22 into the gas passage 50.

[0025] <Holding member> The holding member 10 is generally disk-shaped and can be formed, for example, into a shape having a diameter of about 300 mm and a thickness of about 5 mm. The holding member 10 is an insulating substrate. The material mainly forming the holding member 10 is, for example, ceramics such as alumina (Al2O3) and aluminum nitride (AlN).

[0026] As shown in FIG. 2, the holding member 10 includes a main body portion 11 and a plurality of convex portions 12. The main body portion 11 is substantially disk-shaped, convex upward, and slightly curved. In FIGS. 2 and 4, the curved shape of the main body portion 11 is exaggeratedly shown. The upper surface of the main body portion 11 is a first surface 11A. The first surface 11A is a surface that is positioned upward closer to the center of the main body portion 11 (hereinafter referred to as the center of the main body portion 11) when the main body portion 11 is viewed from above. The lower surface S2 of the main body portion 11 is a concave curved surface that is concave upward. The lower surface S2 of the main body portion 11 is joined to the upper surface S3 of the base member 20 via the joint portion 30.

[0027] <Gas passage> Inside the main body portion 11, a gas passage 50 is formed in which the inside is formed such that a fluid can move. The gas passage 50 has a plurality of gas outflow holes 51 that open to the first surface 11A, a first passage 52 that is connected to the gas injection passage 22 through a hole in the joint portion 30, and a second passage 53 that connects the first passage 52 and the plurality of gas outflow holes 51. A thermally conductive gas such as helium gas flows through the gas passage 50. The thermally conductive gas injected from the gas injection passage 22 of the base member 20 into the first passage 52 flows out from the gas outflow holes 51 through the second passage 53.

[0028] <Chuck electrode> Inside the main body 11 of the holding member 10, a chuck electrode 40 (an example of an electrode member) formed of a conductive material (for example, tungsten, molybdenum, platinum, etc.) is disposed. The chuck electrode 40 is arranged at a position close to the first surface 11A. The shape of the chuck electrode 40 as viewed in the Z-axis direction is, for example, substantially circular. The chuck electrode 40, like the main body 11, is convex upward and slightly curved. In FIGS. 2 and 4, the curved shape of the chuck electrode 40 is exaggeratedly shown. A through hole 41 is formed in the chuck electrode 40. Inside the through hole 41, a gas outflow hole 51 is disposed.

[0029] The plurality of convex portions 12 project upward from the first surface 11A of the main body 11. The plurality of convex portions 12 includes an outer convex portion 13 arranged on the outer peripheral side of the main body 11 and a central convex portion 14 arranged on the central side of the main body 11. For example, the central convex portion 14 may be defined as the convex portion 12 arranged within a predetermined distance (for example, a distance of 50% of the radius of the main body 11) in the XY direction from the center of the main body 11. For example, the outer convex portion 13 may be defined as the convex portion 12 arranged within a predetermined distance (for example, a distance of 50% of the radius of the main body 11) in the XY direction from the outer edge of the main body 11 in the XY direction.

[0030] As shown in FIG. 3, the plurality of convex portions 12 includes a seal band portion 15 arranged on the outer peripheral edge of the main body 11. The seal band portion 15 forms an annular shape when the main body 11 is viewed from above. The seal band portion 15 is included in the outer convex portion 13. The plurality of convex portions 12 excluding the seal band portion 15 are, for example, columnar. The shape of the plurality of convex portions 12 excluding the seal band portion 15 in plan view may be, for example, circular or polygonal.

[0031] As shown in Fig. 2, each convex portion 12 has a top surface 12A and a side surface 12B that connects the top surface 12A and the first surface 11A of the main body portion 11. The top surface 12A is the upper surface of the convex portion 12 and is parallel to the horizontal direction. The top surface 12A is orthogonal to the direction (Z-axis direction) in which the convex portion 12 protrudes from the first surface 11A. The top surfaces 12A of the plurality of convex portions 12 are on the same plane and constitute a holding surface S1. At the corner portion formed by the top surface 12A and the side surface 12B in each convex portion 12, a rounded arc portion 12C is formed. The arc portion 12C smoothly connects between the top surface 12A and the side surface 12B. By forming the arc portion 12C, for example, when performing plasma processing on the wafer W using the electrostatic chuck 1, charge concentration at the corner portion of the convex portion 12 can be suppressed, and arcing inside the convex portion 12 can be suppressed.

[0032] The space defined by the convex portion 12, the first surface 11A, and the wafer W is a storage space 16. A heat conduction gas is introduced into the storage space 16 through the gas flow path 50. Since the seal band portion 15 forms an annular shape surrounding the storage space 16, an inert gas can be stored in the storage space 16 by the contact between the top surface 12A of the seal band portion 15 and the lower surface of the wafer W. Thereby, the temperature adjustment of the wafer W adsorbed on the holding surface S1 can be smoothly performed.

[0033] The radius of curvature of the arc portion 12C of the outer convex portion 13 is smaller than the radius of curvature of the arc portion 12C of the central convex portion 14. Alternatively, the radius of curvature of the arc portion 12C of the convex portion 12 may continuously decrease from the center of the main body portion 11 toward the outer peripheral side of the main body portion 11. Thereby, the contact area between the outer convex portion 13 and the wafer W can be increased. Therefore, it becomes difficult for the heat conduction gas supplied from the gas flow path 50 to leak between the outer convex portion 13 and the wafer W. In particular, when the contact area between the seal band portion 15 and the wafer W increases, it becomes easier to store the heat conduction gas in the storage space 16.

[0034] On the outer peripheral side of the main body portion 11, since the radius of curvature of the rounded portion 12C of the convex portion 12 becomes smaller, it is conceivable that the charge concentration at the corner portion of the convex portion 12 becomes larger than that of the convex portion 12 on the central side of the main body portion 11. However, the protruding dimension D1 of the outer convex portion 13 from the first surface 11A is larger than the protruding dimension D1 of the central convex portion 14 from the first surface 11A. Alternatively, the protruding dimension D1 of the convex portion 12 from the first surface 11A may continuously increase toward the outer peripheral side of the main body portion 11 from the center of the main body portion 11. Here, the protruding dimension D1 of the convex portion 12 from the first surface 11A is the distance between the first surface 11A and the top surface 12A of the convex portion 12. The protruding dimension D1 is a numerical value with a width for each convex portion 12. When comparing the protruding dimensions D1 of a plurality of convex portions 12, the protruding dimension D1 is preferably unified to any one of the maximum value, minimum value, and average value of the distance between the first surface 11A and the top surface 12A of the convex portion 12. According to such a configuration, since the outer convex portion 13 has a larger protruding dimension D1 than the central convex portion 14 and the volume of the convex portion 12 is large, it becomes easier to suppress arcing inside the outer convex portion 13. The radius of curvature of the rounded portion 12C of the outer convex portion 13 and the radius of curvature of the rounded portion 12C of the central convex portion 14 are both preferably less than 1 μm, and more preferably 0.5 μm or less.

[0035] Also, the distance D2 in the protruding direction between the top surface 12A of the outer convex portion 13 and the chuck electrode 40 is larger than the distance D2 in the protruding direction between the top surface 12A of the central convex portion 14 and the chuck electrode 40. Alternatively, the distance D2 in the protruding direction between the top surface 12A of the convex portion 12 and the chuck electrode 40 may continuously increase toward the outer peripheral side of the main body portion 11 from the center of the main body portion 11. Here, the distance D2 is a numerical value with a width for each convex portion 12. When comparing the distances D2 of a plurality of convex portions 12, the distance D2 is preferably unified to any one of the maximum value, minimum value, and average value of the distance D2. According to such a configuration, since the outer convex portion 13 has a larger distance D2 from the chuck electrode 40 than the central convex portion 14, it becomes easier to suppress arcing inside the outer convex portion 13.

[0036] <Method for manufacturing an electrostatic chuck> The above is the configuration of the electrostatic chuck 1 of the present embodiment. Hereinafter, an example of the manufacturing method of the holding member 10 and the electrostatic chuck 1 will be described with reference to FIG. 4. In FIG. 4, the gas flow path 50, the refrigerant flow path 21, and the gas injection path 22 are not shown.

[0037] First, as shown in FIG. 4(A), a base material 60 that will become the holding member 10 is manufactured. The base material 60 is manufactured by firing a sheet laminate formed by laminating a green sheet (ceramic green sheet). An internal space that will become the gas flow path 50 and a conductive layer that will become the chuck electrode 40 are provided inside the sheet laminate. The base material 60 has a curved shape during the process of firing the sheet laminate.

[0038] As shown in FIG. 4(B), the surface 61 of the base material 60 is polished and flattened. As a result, the flatness of the surface 61 is improved, but it is a curved surface that is slightly convex upward. The base material 60 is joined to the base member 20 via the joining portion 30.

[0039] As shown in FIG. 4(C), the surface 61 of the base material 60 is blasted, and grooves are dug from the surface 61 by a predetermined depth. As a result, a protrusion 62 that will become the convex portion 12 is formed.

[0040] As shown in FIG. 4(D), the protruding end of the protrusion 62 is lapped to form the convex portion 12. Specifically, the top surface 12A and the rounded portion 12C of the convex portion 12 are formed. Here, the top surfaces 12A of the plurality of convex portions 12 are arranged on the same plane parallel to the horizontal direction. In FIG. 4(C), the surface 61 of the base material 60 is a curved surface that is slightly convex upward. In the lapping process, the protruding end of the protrusion 62 closer to the center of the main body portion 11 is cut more than the protrusion 62 away from the center of the main body portion 11. As a result, the radius of curvature of the rounded portion 12C of the central convex portion 14 becomes larger than that of the outer convex portion 13, and the protruding dimension D1 of the central convex portion 14 becomes smaller than that of the outer convex portion 13 (see FIG. 2). Thus, the manufacturing of the electrostatic chuck 1 is completed.

[0041] <Effect of Embodiment 1> As described above, the holding member 10 of Embodiment 1 includes a main body portion 11 having a first surface 11A and a plurality of convex portions 12 protruding from the first surface 11A. A gas flow path 50 opening to the first surface 11A is formed in the main body portion 11. The plurality of convex portions 12 include an outer convex portion 13 arranged on the outer peripheral side of the main body portion 11 and a central convex portion 14 arranged on the central side of the main body portion 11. At the corner of each convex portion 12, a rounded portion 12C having a rounded shape is formed. The radius of curvature of the rounded portion 12C of the outer convex portion 13 is smaller than the radius of curvature of the rounded portion 12C of the central convex portion 14, and the protruding dimension D1 of the outer convex portion 13 from the first surface 11A is larger than the protruding dimension D1 of the central convex portion 14 from the first surface 11A.

[0042] According to such a configuration, by forming the rounded portion 12C at the corner of the convex portion 12, it is possible to suppress the charge concentration at the corner of the convex portion 12 and suppress the arcing inside the convex portion 12.

[0043] In the outer convex portion 13, the radius of curvature of the rounded portion 12C is smaller compared to the central convex portion 14. Therefore, the contact area between the outer convex portion 13 and the object (wafer W) can be increased. Thus, the heat conduction gas supplied from the gas flow path 50 is less likely to leak between the outer convex portion 13 and the object.

[0044] In the outer convex portion 13, since the radius of curvature of the rounded portion 12C is smaller compared to the central convex portion 14, it is considered that arcing is more likely to occur inside the outer convex portion 13 than inside the central convex portion 14. However, in the outer convex portion 13, since the protruding dimension D1 of the convex portion 12 from the first surface 11A is large, arcing inside the convex portion 12 can be suppressed.

[0045] In Embodiment 1, an electrode member (chuck electrode 40) is embedded on the first surface 11A side inside the main body 11. The convex portion 12 has a top surface 12A orthogonal to the protruding direction in which the convex portion 12 protrudes from the first surface 11A. The distance D2 in the protruding direction between the top surface 12A of the outer convex portion 13 and the electrode member is larger than the distance D2 in the protruding direction between the top surface 12A of the central convex portion 14 and the electrode member.

[0046] According to such a configuration, by increasing the distance D2 in the protruding direction between the outer convex portion 13 and the electrode member, it is possible to suppress the occurrence of arcing on the outer periphery of the main body 11.

[0047] [Details of Embodiment 2 of the Present Disclosure] A specific example of Embodiment 2 of the present disclosure will be described with reference to FIG. 5. For the configurations similar to those in Embodiment 1, the same reference numerals as in Embodiment 1 may be used, and the description may be omitted. Also, the description of the same operational effects as in Embodiment 1 will be omitted. As shown in FIG. 5, the electrostatic chuck 101 of Embodiment 2 includes a holding member 110, a base member 20, and a joining portion 30. The holding member 110 includes a plurality of convex portions 12 and a main body 11 configured in the same manner as in Embodiment 1.

[0048] The chuck electrode 140 of the holding member 110 is not formed in the portion overlapping the convex portion 12 in the protruding direction of the convex portion 12. In other words, the chuck electrode 140 has a non-formation region 142 in the portion overlapping the convex portion 12 in the protruding direction of the convex portion 12. The non-formation region 142 is a hole penetrating the chuck electrode 140. The non-formation region 142 is filled by a part of the main body 11. According to such a configuration, when charge concentration occurs in the convex portion 12, the distance between the convex portion 12 and the chuck electrode 140 can be widened, so that arcing is less likely to occur between the convex portion 12 and the chuck electrode 140.

[0049] <Effects of Embodiment 2> In the holding member 110 of Embodiment 2, a chuck electrode 140, which is an electrode member, is embedded on the first surface 11A side inside the main body portion 11, and when viewed from the protruding direction in which the convex portion 12 protrudes from the first surface 11A, the electrode member is not formed at a position overlapping the convex portion 12.

[0050] According to such a configuration, since the electrode member is not formed at a position overlapping the convex portion 12 of the electrode member in the protruding direction, it is possible to suppress the occurrence of arcing between the convex portion 12 and the electrode member when charge concentration occurs in the convex portion 12.

[0051] <Other Embodiments> (1) In Embodiments 1 and 2, the chuck electrodes 40 and 140 are exemplified as the electrode members, but electrode members other than the chuck electrode may be employed. (2) In Embodiments 1 and 2, the top surface 12A of the convex portion 12 was a flat surface, but the top surface of the convex portion may be a gently curved surface.

Description of Reference Numerals

[0052] 1, 101... Electrostatic chuck (holding device) 10, 110... Holding member 11... Main body portion 11A... First surface 12... Convex portion 12A... Top surface 12B... Side surface 12C... Rounded portion 13... Outer convex portion 14... Central convex portion 15... Seal band portion 16... Storage space S1... Holding surface S2... Bottom surface 20... Base member 21... Refrigerant flow path 22... Gas injection path S3... Top surface S4... Bottom surface 30... Joint portion 40, 140... Chuck electrode (electrode member) 41... Through hole 142... Non - formation region 50... Gas flow path 51... Gas outflow hole 52... First flow path 53... Second flow path 60... Substrate 61... Surface 62... Protrusion D1... Protrusion dimension of the convex portion 12 from the first surface 11A D2... Distance in the protruding direction between the top surface 12A of the convex portion 12 and the electrode member W... Wafer (object)

Claims

1. A holding member comprising a main body portion having a first surface and a plurality of convex portions protruding from the first surface, wherein a gas flow path opening to the first surface is formed in the main body portion, the plurality of convex portions include outer convex portions arranged on the outer peripheral side of the main body portion and central convex portions arranged on the central side of the main body portion, rounded portions having a rounded shape are formed at the corners of each of the convex portions, the radius of curvature of the rounded portion of the outer convex portion is smaller than the radius of curvature of the rounded portion of the central convex portion, and the protruding dimension of the outer convex portion from the first surface is larger than the protruding dimension of the central convex portion from the first surface.

2. An electrode member is embedded on the first surface side inside the main body portion, each convex portion has a top surface orthogonal to the protruding direction in which the convex portion protrudes from the first surface, and the distance in the protruding direction between the top surface of the outer convex portion and the electrode member is larger than the distance in the protruding direction between the top surface of the central convex portion and the electrode member. The holding member according to claim 1.

3. An electrode member is embedded on the first surface side inside the main body portion, and when viewed from the protruding direction in which the convex portion protrudes from the first surface, the electrode member is not formed at a position overlapping the convex portion. The holding member according to claim 1 or claim 2.

Images