JP2002231793A - Wafer-supporting member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer-supporting member that can prevent cracks from being produced near the corner of a conductive film as an internal electrode and can be used for a long time even under environmental conditions of a repeated heat cycle. SOLUTION: In a wafer-supporting member 11, one main plane of a plate- shaped ceramic body 12 is a plane 13 on which a wafer W is placed, and at least two conductive films 15a, 15b are buried at the same depth in the plate- shaped ceramic body 12. At least one conductive film 15b has a corner, the shortest distance between the corner and the other conductive film 15a is 25 mm or less, and the corner is shaped like an arc P.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention mainly relates to a plasma C
Film forming devices such as VD, low pressure CVD, photo CVD, PVD,
The present invention relates to a wafer support member used for an etching apparatus such as plasma etching and optical etching.

[0002]

2. Description of the Related Art Conventionally, in a film forming apparatus such as a plasma CVD, a low pressure CVD, an optical CVD, and a PVD used in a manufacturing process of a semiconductor device, and an etching apparatus such as a plasma etching and an optical etching, a wafer such as a silicon wafer is used. A wafer support member is used to support the wafer.

[0003] As shown in FIG. 4, the structure of a general wafer support member is such that one main surface of a plate-like ceramic body 32 is a mounting surface 33 on which a wafer W is mounted. At the same depth in the plate-shaped ceramic body 32,
A conductor film 35 as an internal electrode 34 is buried, and power is supplied to the internal electrode 34 from a power supply terminal 36 provided on the other main surface of the plate-shaped ceramic body 32.

When the wafer support member 31 is used as a heater, a voltage is applied to the conductive film 35 to generate heat, so that the wafer W mounted on the mounting surface 33 can be heated. When used as an electrostatic chuck, the wafer W is placed on the mounting surface 33 by applying a voltage to the conductive film 35 and developing an electrostatic attraction force between the internal electrode 35 and the wafer W. And when used as a susceptor for plasma generation, the internal electrode 34
By applying high-frequency power between the device and another electrode (not shown) provided above the mounting surface 33 to generate plasma, the plasma is applied to the wafer W mounted on the mounting surface 33. I was able to do it.

Incidentally, such a wafer supporting member 31
When the internal electrode 35 is for a heater, for example, as shown in FIG. 5A, an arc-shaped strip-shaped conductor film 35a is embedded as the internal electrode 34 embedded in the plate-shaped ceramic body 32. A concentric arrangement is used, and a pattern shape in which adjacent conductive films 35a are connected by a linear strip-shaped conductive film 35b is used, and the internal electrodes 35 are used for electrostatic chucking or plasma generation. 5B, for example, as shown in FIG. 5B, two comb-shaped conductor films 35a are arranged in such a pattern that the teeth are alternately positioned. c)
As shown in FIG. 1, a pattern in which two semicircular conductive films 35a are arranged to form a circle has been used.

When the internal electrode 34 is for a heater, it is necessary to minimize the distance between the adjacent conductor films 35a and 35b in order to heat the wafer W uniformly. In order to generate uniform electrostatic attraction force on the wafer W or generate uniform plasma, the distance between the two conductor films 35a and 35b needs to be as short as possible. The internal electrode 34 having a pattern shape is also designed so that the space between the adjacent conductor films 35a and 35b is made as small as possible.

[0007]

However, FIG. 5 (a)
Internal electrode 3 having a pattern shape as shown in FIGS.
When the wafer support member 31 having the embedded conductors 4 embedded therein and having a narrow gap between the adjacent conductor films 35a and 35b is used in an environment where a thermal cycle is applied, the corner portions of the conductor films 35a and 35b There is a problem that a crack originating from the above occurs, and the plate-shaped ceramic body 32 is damaged in severe cases.

Further, such a problem is caused by the problem of the wafer support member 3.
Not only during use of the wafer support member 1 but also during the manufacturing process of the wafer support member 31. That is, since a heat cycle is also applied to the process of manufacturing the plate-shaped ceramic body 32 by firing the ceramic molded body in which the conductor films 35a and 35b are embedded, the conductor film 3 is included in the fired plate-shaped ceramic body 32.
There has been a problem that cracks originating from the corners of 5a and 35b are generated and damaged.

When the wafer supporting member 31 having a crack in the plate-shaped ceramic body 32 is used as a heater, there is a difference in how heat is transmitted between the ceramic portion having a crack and the ceramic portion having no crack. W cannot be heated uniformly, and when used as an electrostatic chuck, there is a difference in electrostatic chucking force between the ceramic part having cracks and the ceramic part having no cracks. Therefore, the wafer W cannot be fixed to the mounting surface 33, and when the wafer W is detached, it is difficult for the electric charge of the ceramic portion having cracks to escape, so that the detachment responsiveness of the wafer W is impaired. When used as a susceptor for generation, there is a difference in plasma density between the ceramic part with cracks and the ceramic part without cracks. Come, there is a problem can not be irradiated uniform plasma on the wafer W.

[0010]

SUMMARY OF THE INVENTION In view of the above problems, the present invention is directed to a first aspect of the present invention, wherein one main surface of a plate-shaped ceramic body is used as a mounting surface on which a wafer is mounted.
A wafer supporting member in which a strip-shaped conductor film is embedded in the plate-shaped ceramic body, wherein the strip-shaped conductor film is provided with a corner portion in a part thereof to form opposing regions, and is formed at the corner portion. The shortest distance between the opposing regions is 25 mm or less, and the corners of the corners are arc-shaped.

According to a second aspect of the present invention, one of the main surfaces of the plate-shaped ceramic body is used as a mounting surface on which a wafer is mounted, and at least two conductor films are formed at the same depth in the plate-shaped ceramic body. Embedded in the wafer support member, wherein the at least one conductive film has a corner, and the shortest distance from this corner to another conductive film is 25 m.
m or less, and the corners of the corners are arc-shaped.

The invention according to claim 3 is characterized in that the radius of curvature of the arc-shaped corner is 0.2 mm to 15 mm.

[0013]

Embodiments of the present invention will be described below.

FIG. 1 is a view showing a heater which is an example of a wafer support member according to the present invention. FIG. 1 (a) is a perspective view thereof, and FIG.
3A is a cross-sectional view taken along line XX of FIG. 3A, and FIG. 3C is a plan view showing a pattern shape of an internal electrode.

The wafer support member 1 serving as a heater includes:
The upper surface of the disk-shaped plate-shaped ceramic body 2 is used as the mounting surface 3 on which the wafer W is placed, and the plate-shaped ceramic body 2 has an arc-shaped band shape as shown in FIG. The conductive films 5a are arranged concentrically, and the adjacent conductive films 5a have a linear shape.
The internal electrodes 4 having a pattern shape tied together by burying are embedded at the same depth. A power supply terminal 6 electrically connected to the conductor films 5a and 5b is joined to the lower surface of the plate-like ceramic body 2 respectively. It is.

The conductor films 5a, 5b forming the internal electrodes 4
In order to uniformly heat the wafer W placed on the mounting surface 3,
The distance between the adjacent conductor films 5a and the adjacent conductor films 5b is designed to be as small as possible, and at least the shortest distance L from the corner of one of the opposed conductor films 5b to the other conductor film 5b is determined. The corners of the corners of the conductor film 5b located at a position where the shortest distance L is not more than 25 mm are formed in an arc shape P.

In order to heat the wafer W placed on the mounting surface 3 using the wafer support member 1, a voltage is applied between the power supply terminals 6 to cause the internal electrodes 4 to generate heat. Is heated to heat the wafer W.

FIG. 2 is a view showing an electrostatic chuck which is another example of the wafer support member according to the present invention. FIG. 2 (a) is a perspective view thereof, FIG. 2 (b) is a sectional view taken along line YY of FIG. (C) is a plan view showing a pattern shape of the internal electrode.

The wafer support member 11 serving as the electrostatic chuck is formed by placing the upper surface of a disc-shaped plate-shaped ceramic body 12
In addition to the mounting surface 13 on which the wafer W is mounted, a pair of comb-shaped conductor films 15a and 15 as shown in FIG.
b is formed by embedding an internal electrode 14 having a pattern shape in which tooth portions are alternately arranged at the same depth, and a pair of conductor films 15 a,
The power supply terminals 16 electrically connected to the power supply terminals 15b are respectively joined.

Further, a pair of conductor films 1 forming the internal electrodes 14 are formed.
5a and 15b are designed so that the distance between the conductor films 15a and 15b is as small as possible in order to develop a uniform electrostatic attraction force on the mounting surface 13. At least one of the conductor films 15b opposed to each other is designed. The shortest distance L from the corner to the other conductor film 15a is set to 25 mm or less, and the corner of the corner of the conductor film 115b located at a portion where the shortest distance L is 25 mm or less is formed in an arc P. is there.

In order for the wafer W to be attracted to the mounting surface 13 by using the wafer support member 11, the power supply terminal 16
When a voltage is applied between them, an electrostatic attraction force is developed between the wafer W and the mounting surface 13, so that the wafer W is forcibly fixed to the mounting surface 13 by the electrostatic attraction force. I have.

FIGS. 3A and 3B show a plasma generating susceptor as another example of the wafer supporting member according to the present invention. FIG. 3A is a perspective view thereof, and FIG. 3B is a sectional view taken along line ZZ of FIG. , (C)
FIG. 3 is a plan view showing a pattern shape of an internal electrode.

The wafer supporting member 21 serving as the plasma generating susceptor includes a disc-shaped plate-like ceramic body 22.
Is set as the mounting surface 23 on which the wafer W is mounted, and in the vicinity of the mounting surface 23 side in the plate-shaped ceramic body 22,
As shown in FIG. 3C, a pair of semicircular conductor films 25a and 25b are buried at the same depth in a pattern-shaped internal electrode 24 in which the conductor electrodes 25a and 25b are arranged to form a circle. A power supply terminal 26 electrically connected to the pair of conductor films 25a and 25b is provided on the lower surface of the ceramic body 22.
Are joined together.

A pair of conductor films 2 forming the internal electrodes 24
5a and 25b are designed so that the distance between the conductor films 25a and 25b is as small as possible in order to irradiate the wafer W on the mounting surface 23 with uniform plasma. The shortest distance L from the corner to the other conductor film 25a is set to 25 mm or less, and the corner of the corner of the conductor film 25b located at a position where the shortest distance L is 25 mm or less is formed in an arc P. is there.

To irradiate the wafer W with plasma using the wafer support member 21, the mounting surface 23
When a voltage is applied between an electrode (not shown) separately provided above the internal electrode 24 and the internal electrode 24, plasma is generated between the electrodes, and the wafer W can be irradiated with the plasma.

Then, these wafer support members 1, 1
The conductor films 5a, 5b, 15a, and 15a are adjacent to the corners of the conductor films 5a, 5b, 15a, 15b, 25a, and 25b forming the internal electrodes 4, 14, and 24, respectively.
b, 25a, and 25b, the shortest distance L is set to 25 mm or less, and the conductor films 5a, 5b, 15a, 15b, 25a, and 2 at the portion where the shortest distance L is 25 mm or less.
Since the corners of the corners of 5b are formed in the shape of an arc P, the conductor films 5a, 5b may be used in an environment where a thermal cycle is applied or when the plate-like ceramic bodies 2, 12, 22 are manufactured. , 15a, 15b, 25a, 25b as starting points, cracks do not occur in the plate-shaped ceramic bodies 2, 12, 22 so that they can be used for a long time.

That is, the present inventor has proposed a plate-shaped ceramic body 2,
As a result of repeated studies on the causes of cracks in the conductor films 12 and 22, the conductor films 5a and 5b adjacent to the corners of the conductor films 5a, 5b, 15a, 15b, 25a and 25b forming the internal electrodes 4, 14, and 24 were formed. , 15a, 15b,
If the shortest distance L to 25a, 25b exceeds 25 mm, cracks are likely to occur in the T-plate-shaped ceramic bodies 2, 12, 22 due to thermal stress. The membranes 5a, 5b, 15a,
It has been found that when the corners of 15b, 25a and 25b have sharp corners, cracks are likely to occur starting from these corners.

The reason is that the conductor films 5b, 15a, 15
b, 25a, 25b are plate-like ceramic bodies 2, 12, 22
For example, the plate-like ceramic bodies 2, 12, and 24 are laminated by sandwiching the internal electrodes 4, 14, and 24 between a plurality of ceramic green sheets.
22 is manufactured, the conductor films 5b, 15a, 15b, 2
If there is a portion where the distance between 5a and 25b is small, the conductor film 5b,
The ceramic green sheets near the corners of the conductor films 5b, 15a, 15b, 25a, 25b are hard to adhere to each other due to the thickness of the conductor films 5a, 15b, 25a, 25b, and particularly when the corners have sharp corners. The adhesion between the ceramic green sheets near the corners of the conductor films 5b, 15a, 15b, 25a, 25b is poor, and the conductor films 5b, 15a, 15b, 25
This is probably because the strength of the ceramic portion near the corners of a and 25b is reduced. When the plate-shaped ceramic bodies 2, 12, 22 are manufactured by placing the internal electrodes 4, 14, 24 on the ceramic molded body, further filling the ceramic powder and performing uniaxial pressure molding, the conductor films 5b, If there is a portion where the distance between 15a, 15b, 25a, 25b is small, the conductor films 5b, 15a, 15
The packing density of the ceramic powder in the vicinity of the corners of the conductor films 5b, 25a, 25b tends to be small, and particularly, if the corners have sharp corners, the conductor films 5b, 15
a, 15b, 25a, and 25b, since the density of the filled ceramic powder near the corners is small, the conductor films 5b,
It is considered that the strength of the ceramic portion near the corners of 15a, 15b, 25a, and 25b is reduced. Moreover, the conductor films 5b, 15a, 15
The b, 25a, and 25b having a sharp outer shape at the corners are likely to concentrate stress even in shape, and therefore, when used in an environment where a repeated thermal cycle is applied, the conductive film 5b, 1
It is considered that cracks originating from the corners of 5a, 15b, 25a, and 25b occur.

The inventor of the present invention has conducted intensive studies on a structure in which cracks are unlikely to occur, and found that certain conductive films 5b, 15a, 1 forming the internal electrodes 4, 14, 24 are formed.
The shortest distance L from the corners of 5b, 25a, 25b to the adjacent conductor films 5b, 15a, 15b, 25a, 25b is not more than 25 mm, and the shortest distance L is 2 mm.
Conductive films 5b, 15a, 15 located at a portion of 5 mm or less
The plate-shaped ceramic bodies 2, 12, 22 are laminated by sandwiching the internal electrodes 4, 14, 24 between a plurality of ceramic green sheets by setting the outer shape of the corners of the b, 25a, 25b to curve P. When manufacturing, the conductor film 5
b, 15a, 15b, 25a, 25b can improve the adhesion between the ceramic green sheets in the vicinity of the corners, and the internal electrodes 4, 14, 24 are placed on the ceramic molded body and further filled with ceramic powder. And press-formed uniaxially to obtain plate-shaped ceramic bodies 2 and 1
2 and 22, the conductor films 5b, 15a, 1
Since the packing density of the ceramic powder near the corners of the conductive films 5b, 25a, 25b can be increased, the conductive films 5b, 15a, 15b, 25
Since it is possible to prevent the strength of the ceramic portion from decreasing near the corners of the a and 25b, the plate-shaped ceramic bodies 2 and 1 can be used even in an environment where a heat cycle is applied.
The occurrence of cracks in the substrates 2 and 22 can be greatly reduced.

Thus, the wafer support members 1, 1 according to the present invention are provided.
When the heaters 1 and 21 are used as heaters, the wafer W can be heated uniformly over a long period of time, and when they are used as electrostatic chucks, the wafers W can be suction-fixed with a uniform suction force over a long period of time. Further, when used as a plasma generating susceptor, uniform plasma can be stably applied to the wafer W for a long period of time.

In order to effectively prevent the occurrence of cracks, the curvature radius R of the curve P forming the corners of the conductor films 5b, 15a, 15b, 25a, 25b should be 0.2 mm.
It is preferable to set it to 15 mm.

If the radius of curvature R is less than 0.2 mm, the effect of making the outer shape of the corner into a curve P is small, and when a heat cycle is applied, the plate-shaped ceramic bodies 2, 12,.
This is because a crack is generated in the radius of curvature P.
Exceeds 15 mm, the conductor films 5b, 15a, 15b,
This is because the resistance value near the corners of the corners 25a and 25b becomes too small as compared with the other parts, and there is a possibility that the flow of current is obstructed and abnormal heat generation occurs.

By the way, such a wafer support member 1,
Plate-shaped ceramic bodies 2, 12, 22 constituting 11, 21
As the material of the ceramic material, a ceramic sintered body mainly composed of alumina, silicon nitride, sialon, and aluminum nitride, which is excellent in wear resistance and heat resistance, can be used. The sintered body has a thermal conductivity of 50 W / m · K or more, and further 100 W / m · K.
It has a high thermal conductivity of at least m · K and has corrosion resistance and plasma resistance to corrosive gases such as fluorine and chlorine, so that the plate-like ceramic bodies 2, 12, 22 can be suitably used.

The conductor layers 5b, 15a, 15b, 25a, 25b forming the internal electrodes 4, 14, 24 form the plate-like ceramic bodies 2, 12, 22 from the viewpoint of enhancing the adhesion to the ceramic sintered body. It is preferable that the ceramic sintered body forming the plate-shaped ceramic bodies 2, 12, and 22 be made of silicon nitride, sialon, or aluminum nitride as a main component. In this case, a high melting point metal such as tungsten, molybdenum, rhenium, and platinum, an alloy thereof, or a carbide or nitride of the high melting point metal may be used.

The conductor films 5b, 15a, 15b, 25
The properties a and 25b may have any property such as a metal foil, a metal plate or a film formed by hardening metal particles.

It should be noted that the present invention is not limited to the above-described embodiment, but may be modified or changed without departing from the scope of the present invention.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an internal electrode in which each corner of a conductive film is formed in an arc shape, and an internal electrode in which each corner of a conductive film is a right angle, and one of the conductive films has An experiment was conducted in which wafer support members having different shortest distances to the other conductor film were prepared, and the presence or absence of breakage of the plate-shaped ceramic body when the thermal cycle test was repeated was performed.

In this experiment, the plate-like ceramic body 2
The AlN content of the ceramic sintered body forming 99.
A 9 wt% aluminum nitride sintered body was used, and its shape was a disk having a diameter of 12 inches (about 300 mm) and a thickness of 12 mm. Tungsten was used for the conductor film forming the internal electrodes, and the pattern shape shown in FIG. 1C was used.

Then, 20 pieces each having a different minimum distance are prepared, and whether or not there is any damage at the time of manufacturing the plate-like ceramic body, and each wafer support member is air-tightly installed in a vacuum processing chamber of the CVD apparatus. A heat cycle test was conducted in which cooling was performed after heating from room temperature to 500 ° C. at a heating rate of 40 ° C./min, and the number of times until cracks occurred in the plate-shaped ceramic body was measured.

The results are as shown in Table 1.

[0041]

[Table 1]

As a result, the shortest distance from the corner of one conductive film to the other conductive film is set to 25 mm or less, and the corner of the corner of the conductive film in the portion where the shortest distance is 25 mm or less is formed into a circle. If it is formed in an arc shape, when the shortest distance is 25 mm, one plate-shaped ceramic body is broken in 500 heat cycle tests, but otherwise, when manufacturing the plate-shaped ceramic body and in the heat cycle test No breakage of the plate-like ceramic body was observed.

From the above, the shortest distance from the corner of one conductive film embedded in the plate-shaped ceramic body to the other conductive film is set to 25 mm or less, and the conductor located at a position where the shortest distance is 25 mm or less is set. It can be seen that the corners of the corners of the film should be arc-shaped.

In this embodiment, a wafer supporting member as a heater is shown as an example, but the same result is obtained with a wafer supporting member as an electrostatic chuck or a plasma generating susceptor. (Experimental Example 2) Next, the shortest distance from the corner of one conductive film to the other conductive film is set to 15 mm, and the curvature of the arc-shaped corner of the conductive film located at the position where the shortest distance is 15 mm. An experiment was conducted to determine whether the plate-shaped ceramic body was damaged when the thermal cycle test was repeated under the same conditions as in Example 1 except that the radius was changed.

The results are as shown in Table 2.

[0046]

[Table 2]

As a result, by setting the radius of curvature of the arc-shaped corner portion of the conductor film in the range of 0.2 mm to 15 mm, no breakage of the plate-like ceramic body is observed,
It turns out that it is especially excellent.

From this, it is preferable that the radius of curvature of the arc-shaped corner portion of the conductive film is set in the range of 0.2 mm to 15 mm.

[0049]

As described above, according to the present invention, one main surface of the plate-shaped ceramic body is used as a mounting surface for mounting a wafer, and a strip-shaped conductor film is embedded in the plate-shaped ceramic body. A wafer support member, wherein the strip-shaped conductor film is provided with a corner at a part thereof to form opposed regions, and the shortest distance of the opposed region at the corner is 25 mm or less. At the same time, the corner of the corner portion is formed in an arc shape, or one main surface of the plate-shaped ceramic body is set as a mounting surface on which a wafer is placed, and at least two of the same depth in the plate-shaped ceramic body. A wafer support member having at least one conductive film embedded therein, wherein the at least one conductive film has a corner portion, and the shortest distance from the corner portion to another conductive film is 25 mm or less; By making the corners of the ceramic portion arc-shaped, it is possible to suppress a decrease in the strength of the ceramic portion in the vicinity of the corner portion of the conductor film, so that the plate-shaped ceramic body can be used even in an environment where repeated thermal cycles are applied. It can be used for a long period of time because it is possible to prevent the occurrence of cracks and breakage.

Therefore, if the wafer supporting member of the present invention is used as a heater, the wafer can be heated uniformly,
Further, when used as an electrostatic chuck, the wafer can be suction-fixed with a uniform electrostatic attraction force, and when used as a plasma generating susceptor, the wafer can be irradiated with uniform plasma.

[Brief description of the drawings]

1A and 1B are views showing a heater as an example of a wafer support member according to the present invention, wherein FIG. 1A is a perspective view thereof, FIG. 1B is a cross-sectional view taken along line XX of FIG. 1A, and FIG. 3 is a plan view showing a pattern shape of FIG.

2A and 2B are views showing an electrostatic chuck as another example of the wafer support member according to the present invention, wherein FIG. 2A is a perspective view thereof, FIG. 2B is a sectional view taken along line YY of FIG. () Is a plan view showing the pattern shape of the internal electrode.

3A and 3B are diagrams showing a plasma generating susceptor as another example of the wafer support member according to the present invention, wherein FIG. 3A is a perspective view thereof, FIG. 3B is a sectional view taken along line ZZ of FIG. (c) is a plan view showing the pattern shape of the internal electrode.

FIG. 4 is a perspective view showing a conventional wafer support member.

FIGS. 5A to 5C are plan views showing various patterns of internal electrodes provided in a conventional wafer support member.

[Explanation of symbols]

1, 11, 21, 31: wafer support member 2, 12, 22, 32: plate-shaped ceramic body 3, 13, 23, 33: mounting surface 4, 14, 24, 34: internal electrode 5, 5a, 5b, 15a, 15b, 25a, 25b: conductive film 6, 16, 26, 36: power supply terminal W: wafer P: arc-shaped R: radius of curvature

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H05B 3/20 328 H05B 3/20 328 7/08 7/08 A F term (Reference) 3K034 AA19 AA22 BB06 BC17 HA10 JA02 JA10 3K084 CA01 CA07 3K092 PP09 QA05 QB45 RF03 RF11 RF27 SS18 VV31 5F031 CA02 HA02 HA18 HA37 MA28 MA29 MA32 PA11 5F045 AA06 AA08 AA11 AA19 BB20 DP02 DQ10 EB03 EK09 EM09

Claims (3)

[Claims] 1. A wafer support member wherein one main surface of a plate-shaped ceramic body is a mounting surface on which a wafer is mounted, and a strip-shaped conductor film is embedded in the plate-shaped ceramic body.
The strip-shaped conductor film is provided with a corner portion at a part thereof to form opposed regions, and the shortest distance of the opposed region at the corner portion is 25 mm or less, and the corner portion of the corner portion is formed. Has a circular arc shape. 2. A wafer support member having one main surface of a plate-shaped ceramic body as a mounting surface on which a wafer is mounted, and at least two conductor films embedded at the same depth in the plate-shaped ceramic body. The at least one conductive film has a corner, and the shortest distance from the corner to the other conductive film is 25 mm or less, and the corner of the corner has an arc shape. A wafer support member characterized by the above-mentioned. 3. A curvature radius of the arc-shaped corner portion is 0.2.
3. The wafer support member according to claim 1, wherein the thickness of the wafer support member is in a range of about 15 mm to about 15 mm. 4.