JP4066329B2 - Electrostatic chuck manufacturing method and electrostatic chuck obtained using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic chuck manufacturing technique. In particular, the present invention relates to a method for manufacturing an electrostatic chuck in which an electrode is provided on a base with an insulating layer embedded therein.
[0002]
[Prior art]
For example, in a thin film forming process or a dry etching process in a semiconductor manufacturing process, since a required film forming process or etching process is performed on a flat article such as a wafer, it is necessary to securely hold it on a mounting table. As a holding device that meets these requirements, an electrostatic chuck that holds an article in close contact using electrostatic action is widely used.
[0003]
A conventional electrostatic chuck is formed by plasma-spraying ceramics such as alumina to form an insulating film so as to cover a metal plate electrode. For this reason, it can be manufactured with a relatively small number of steps, and the obtained electrostatic chuck has the advantage of being excellent in heat resistance and durability. However, recently, a type in which a lower insulating layer, an electrode layer, and an upper insulating layer are sequentially formed on a base by thermal spraying is becoming mainstream.
[0004]
However, the insulating film, that is, the sprayed coating of the electrostatic chuck obtained in this way is porous with an infinite number of minute pores, so that the withstand voltage characteristic is not so high. Therefore, it is difficult to obtain a large holding force. In addition, a discharge phenomenon may occur in the pores. That is, a problem that current flows through the pores rarely occurs between the adsorbed and held article and the electrode layer, and there is still room for improvement. In view of such circumstances, a sealing treatment technique has been proposed in which the pores are filled with a resin to improve the withstand voltage characteristics and to improve the adsorption holding capability (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP-A-6-196548 [0006]
[Problems to be solved by the invention]
Incidentally, the electrode layer is usually formed by spraying a metal material such as nickel, tungsten, or aluminum on the lower insulating layer. Therefore, prior to this thermal spraying, the electrode layer forming region is surrounded by the masking tape, but a problem arises when it is removed. That is, when the masking tape is peeled off, the edge of the formed electrode layer may be dragged to protrude upward. That is, burrs are inevitably generated in the electrode layer during the production.
[0007]
In addition, at the site where this burr exists, the distance between the article to be adsorbed and held and the electrode layer becomes extremely narrow, and the withstand voltage characteristic tends to deteriorate. Therefore, the upper insulating layer cannot be made too thin. By the way, in the electrostatic chuck of the type that holds the article by adsorption using the Coulomb force, it is preferable that the upper insulating layer is as thin as possible. However, for this reason, the upper insulating layer must actually be made considerably thicker. In some cases, sufficient adsorption performance could not be realized. Therefore, the problem to be solved by the present invention is to provide an electrostatic chuck manufacturing technique that exhibits excellent withstand voltage characteristics even when the thickness of the upper insulating layer is small.
[0008]
[Means for Solving the Problems]
In the process of pursuing earnest research to solve the above problems, the present inventors, even if burrs are formed at the edge of the electrode layer during the manufacturing process, will ultimately affect the withstand voltage characteristics of the electrostatic chuck. We thought that it would be good to give appropriate treatment so as not to give. Then, after spraying the material that becomes the electrode layer in the area surrounded by the masking tape, removing the masking tape, the edge of the formed electrode layer is polished into a tapered shape using, for example, a diamond tool, I found out that the problems mentioned above do not occur. That is, by doing so, it is possible to obtain an electrostatic chuck that exhibits excellent withstand voltage characteristics even when the thickness of the upper insulating layer is small.
[0009]
In addition, the present inventors have thought that if the burrs are not formed at the edge of the electrode layer during the production, the deterioration of the withstand voltage characteristic will be suppressed. And in this case, when the masking jig has a special shape, that is, when placed on the lower insulating layer, this electrode layer forming region is formed so that a gap is formed between the electrode layer forming region on the surface of the lower insulating layer. It has been found that a material to be an electrode layer may be sprayed in a state where a masking jig having a protruding portion protruding above is disposed on the lower insulating layer. When thermal spraying is performed using such a jig, the amount of metal particles deposited gradually decreases toward the jig body due to the action of the overhanging portion. Will not occur. As a result, it is possible to obtain an electrostatic chuck that exhibits excellent withstand voltage characteristics even when the thickness of the upper insulating layer is small.
[0010]
The present invention has been made based on these findings,
The above issues
A base, a lower insulating layer formed on the upper surface of the base, an electrode layer formed on the lower insulating layer, and an upper portion formed on the lower insulating layer so as to cover the electrode layer A method for manufacturing an electrostatic chuck comprising an insulating layer,
A first step of spraying a material to be the lower insulating layer on the upper surface of the base;
A second step of thermally spraying a material to be the electrode layer on a region surrounded by a masking tape on the lower insulating layer obtained in the first step;
A third step of removing the masking tape and polishing the edge of the electrode layer obtained in the second step into a tapered shape;
After this third step is completed, a material to be the upper insulating layer is sprayed on the lower insulating layer so as to cover the electrode layer , and then the tapered edge of the electrode layer is covered. And a fourth step of polishing the surface of the upper insulating layer into a flat surface so that the thickness of the upper insulating layer increases toward the edge of the electrode layer. Solved by the method.
[0011]
In addition, the above problem
A base, a lower insulating layer formed on the upper surface of the base, an electrode layer formed on the lower insulating layer, and an upper portion formed on the lower insulating layer so as to cover the electrode layer A method for manufacturing an electrostatic chuck comprising an insulating layer,
A first step of spraying a material to be the lower insulating layer on the upper surface of the base;
An overhang projecting above the electrode layer forming region so that a gap is formed between the electrode layer forming region on the surface of the lower insulating layer when placed on the lower insulating layer obtained in the first step. A second step of thermally spraying a material to be the electrode layer on the lower insulating layer in a state where the masking jig provided with is disposed on the lower insulating layer;
The upper insulating layer is sprayed with a material to be the upper insulating layer so as to cover the electrode layer obtained in the second step, and then the upper edge portion covering the tapered edge of the electrode layer. And a third step of polishing the surface of the upper insulating layer into a flat surface so that the thickness of the insulating layer increases toward the edge of the electrode layer . Solved.
[0012]
In addition , the above problem
An electrostatic chuck obtained using the above manufacturing method,
A base, a lower insulating layer formed on the upper surface of the base by thermal spraying, an electrode layer formed on the lower insulating layer, and thermal spraying on the lower insulating layer to cover the electrode layer An upper insulating layer formed, and the edge of the electrode layer is tapered, and the thickness of the upper insulating layer covering the tapered edge of the electrode layer is the edge of the electrode layer. This is solved by an electrostatic chuck characterized in that the surface of the upper insulating layer is planar .
[0013]
In the present specification, the “tapered shape” means a shape whose thickness decreases toward the end. Therefore, the slope of the tapered edge portion may be flat or may be a curved surface convex upward (or downward).
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The first embodiment of the present invention will be specifically described below with reference to FIGS. 1 is a plan view of the electrostatic chuck according to the present embodiment, FIG. 2 is an enlarged cross-sectional view of the main part of the electrostatic chuck taken along line XX in FIG. 1, and FIGS. It is the schematic which shows the manufacturing procedure of the electrostatic chuck using the manufacturing method which concerns on this embodiment.
[0015]
The electrostatic chuck according to the present embodiment (hereinafter referred to as the present electrostatic chuck) is a monopolar type as shown in FIG. 1 and has a rectangular plate-like outer shape. As will be described in detail later, this electrostatic chuck is obtained by using an electrostatic chuck manufacturing method according to the present embodiment (hereinafter referred to as the present manufacturing method), as can be seen from FIG. As main components, a base 1, a lower insulating layer 2, an electrode layer 3, and an upper insulating layer (dielectric layer) 4 are provided.
[0016]
Among these, the base 1 is comprised from the metal-ceramics composite material (MMC), and the through-hole for installing the electrode terminal mentioned later is actually formed in multiple numbers. However, the material of the base 1 may be basically any material, and is composed of, for example, a single metal such as aluminum, an aluminum alloy, or another low thermal expansion alloy in addition to the metal-ceramic composite material. . Which material is used is selected in consideration of the operating temperature of the electrostatic chuck.
[0017]
Next, regarding the lower insulating layer 2 provided on the upper surface of the base 1, this is formed by plasma spraying, for example, alumina or the like on the upper surface of the base 1. On the other hand, the electrode layer 3 provided on the lower insulating layer 2 has a rectangular shape that is slightly smaller than the base 1, for example, nickel (or a single metal such as aluminum, chromium, cobalt, molybdenum, tungsten, or the like, These alloys are formed by plasma spraying the surface of the lower insulating layer 2. Further, the edge portion is tapered, in other words, the edge portion is composed of an upwardly convex curved surface whose thickness gradually decreases toward the end.
[0018]
The upper insulating layer 4 provided on the lower insulating layer 2 so as to cover the electrode layer 3 is plasma sprayed with, for example, alumina containing a small amount of titanium oxide on the surface of the electrode layer 3 and thus on the lower insulating layer 2. It is formed by doing. The surface roughness Ra of the upper insulating layer 4 is about 0.1 to 2.0 μm. However, besides alumina, an appropriate material can be selected and used according to the required dielectric constant value. In the present embodiment, the monopolar electrostatic chuck is taken as an example, but the technique of the present invention can also be applied to a bipolar electrostatic chuck having two electrodes. Moreover, although the base 1 and the electrode layer 3 were made into the rectangular shape here, it cannot be overemphasized that these shapes are arbitrary.
[0019]
Although not particularly illustrated, the electrode layer 3 is connected to the above-described electrode terminal for power feeding. By applying a voltage to the electrode layer 3 by using this, the electrostatic chuck can attract and hold the article on the surface of the upper insulating layer 4 (at this time, the article is grounded).
[0020]
In the present embodiment, the thickness of the lower insulating layer 2 (in FIG. 2, _{T 1} shown in) and the effective thickness of the upper insulating layer 4 (in FIG. 2, indicated by _{T 2),} were both 100 to 500 [mu] m. If these thicknesses are within this range, sufficient withstand voltage performance can be obtained, so that dielectric breakdown does not easily occur, and furthermore, the difference in thermal expansion from the base 1 is suppressed to such an extent that it does not cause any problems. Cracks and breakage due to thermal shock are less likely to occur. The thickness of the electrode layer 3 (in FIG. 2, indicated by _{T 3)} with respect to which is about 30 to 100 [mu] m. If the thickness of the electrode layer 3 is within this range, a particularly uniform sprayed coating can be obtained, so that unevenness in adsorption force does not occur. In addition, since the step between the electrode layer 3 and the lower insulating layer 2 is sufficiently small, the withstand voltage characteristic of the upper insulating layer 4 does not deteriorate due to the presence of the step.
[0021]
Subsequently, the present manufacturing method, that is, the base 1, the lower insulating layer 2 formed on the upper surface, the electrode layer 3 formed thereon, and the upper insulating formed on the lower insulating layer 2 so as to cover it. A manufacturing procedure of the electrostatic chuck including the layer 4 will be described.
[0022]
In order to obtain this electrostatic chuck, first, the surface of the base 1 is uniformly roughened by using a blast material such as alumina or silicon carbide. After the cleaning, an undercoat layer is further formed on the surface of the base 1 for enhancing the adhesion between the base 1 and the insulating layer formed thereon. Specifically, a metal thin film made of a single metal such as nickel, aluminum, chromium, cobalt, molybdenum, or an alloy of these metals is formed on the surface of the base 1 using an arc spraying method or a plasma spraying method. Note that this undercoat layer is not indispensable, and whether or not to provide it is determined in consideration of the use environment of the electrostatic chuck.
[0023]
Subsequently, a material to be the lower insulating layer 2 is sprayed on the undercoat layer and thus on the base 1. That is, the lower insulating layer 2 made of ceramics such as alumina is formed by plasma spraying (first step: see FIG. 3A). However, the undercoat layer is not shown in FIG.
[0024]
When the lower insulating layer 2 is obtained by the first step, the masking tape 5 is attached to the surface so as to surround the electrode layer forming region (the region surrounded by the broken line in FIG. 1). Then, nickel (a material to be an electrode layer) is plasma sprayed in a specific region on the lower insulating layer 2 surrounded by the masking tape 5 to form the electrode layer 3 [second step: FIG. reference〕.
[0025]
Thereafter, the masking tape 5 is removed. At this time, a burr 3a is formed on the edge of the electrode layer 3 obtained in the second step, as shown in FIG. Therefore, in this manufacturing method, this burr 3a is removed using a diamond tool (not shown). That is, the edge of the electrode layer 3 is polished into a tapered shape so that the thickness decreases toward the end [third step: see FIG. 3 (d)].
[0026]
When the third step is completed, plasma spraying of alumina containing a small amount of titanium oxide (material for the upper insulating layer) is performed so as to cover the electrode layer 3 on the electrode layer 3 and thus on the lower insulating layer 2. Then, an upper insulating layer (dielectric layer) 4 is formed [fourth step: see FIG. 3 (e)]. Finally, the electrostatic chuck having a cross section as shown in FIG. 2 is completed by sequentially subjecting the surface of the upper insulating layer 4 to sealing, grinding, and lapping.
[0027]
In addition, as a substance used for the sealing treatment, that is, a substance filled in the pores, colloidal slurry such as silica sol, alumina sol, magnesia sol, or metal alkoxide such as SiO ₂ , Al ₂ O ₃ , TiO _2, etc. Polymers and those containing various resins such as melamine resin, acrylic resin, phenol resin, fluororesin, and silicon resin in addition to these polymers can be mentioned. Filling the pores with such a substance (impregnation into the insulating layer) is performed by setting a semi-finished electrostatic chuck in a vacuum desiccator and vacuuming it. As a result, the slurry permeates into the inside from the surface of the insulating layer. The slurry filled in the pores in this way is dried in consideration of its characteristics, and then the above-described grinding process is performed.
[0028]
As described above, in this manufacturing method, even if the burr 3a is formed at the edge of the electrode layer 3 during the manufacturing, appropriate processing is performed so that it does not finally affect the withstand voltage characteristics of the electrostatic chuck. It is characterized by. That is, the edge of the electrode layer 3 formed by thermal spraying is polished into a taper shape using a diamond tool, and the burr 3a generated when the masking tape 5 is peeled off is removed. Therefore, there has been no problem that has been caused by the presence of the burr 3a until now, and even if the thickness of the upper insulating layer 4 is small, the electrostatic chuck can exhibit excellent withstand voltage characteristics. it can.
[0029]
Next, the second embodiment of the present invention will be specifically described with reference to FIGS. 4 and 5. Here, FIGS. 4A to 4D are schematic views showing the manufacturing procedure of the electrostatic chuck using the manufacturing method according to this embodiment, and FIG. 5 is a perspective view of the masking jig shown in a partially broken state. FIG.
[0030]
The electrostatic chuck obtained by using the manufacturing method according to the present embodiment (hereinafter referred to as the present manufacturing method again) generally has the same shape and structure as those of the first embodiment. That is, the electrostatic chuck also has a base 11, a lower insulating layer 12 formed on the upper surface thereof, an electrode layer 13 formed thereon, and an upper insulating layer formed on the lower insulating layer 12 so as to cover it. It is composed of layer 14.
[0031]
Also for this manufacturing method used to obtain such an electrostatic chuck, the procedure up to the middle is the same as that in the first embodiment. That is, first, the surface of the base 11 is uniformly roughened using a blast material, and after cleaning, an undercoat layer is formed thereon if necessary. Subsequently, ceramics such as alumina (a material that becomes the lower insulating layer) is plasma sprayed on the base 11 provided with the undercoat layer, thereby forming the lower insulating layer 12 [first step: FIG. see a)]. However, the undercoat layer is not shown in FIG.
[0032]
Next, as shown in FIG. 4B, a specially shaped masking jig 15 shown in FIG. 5 is disposed on the lower insulating layer 12 obtained in the first step. Here, the masking jig 15 will be described.
[0033]
The masking jig 15 has a mouth shape made of stainless steel (SUS304) and has an L-shaped cross section as shown in FIG. That is, the masking jig 15 includes an overhanging portion 15a. When this jig | tool 15 is mounted on the lower insulating layer 12, this overhang | projection part 15a forms a space | gap between the electrode layer formation area | region (area | region enclosed with the broken line in FIG. 1) on the surface. Thus, it protrudes above this electrode layer formation region. Therefore, the vertical and horizontal dimensions of the opening of the masking jig 15 are slightly smaller than the vertical and horizontal dimensions of the electrode layer forming region. However, the external dimensions of the masking jig 15 are the same as those of the base 1.
[0034]
Incidentally, in this embodiment, the length (indicated by L in FIG. 5) of the overhanging portion 15a is 1-2 mm, the thickness (indicated by W in FIG. 5) is 1-3 mm, and the height of the bottom of the overhanging portion, That is, the gap width (indicated by H in FIG. 5) was set to 1 to 3 mm. Moreover, the overlap amount (indicated by U in FIG. 4) between the projecting portion 15a and the electrode layer forming region was set to be 0.3 to 1.0 mm. Needless to say, the masking jig used in the present manufacturing method is not limited to that shown in FIG. 5, and various other shapes are used as necessary.
[0035]
Now, if the masking jig 15 is disposed on the lower insulating layer 12, in this state, nickel (material that becomes the electrode layer) is plasma sprayed to form the electrode layer 13. [Second step: see FIG. 4 (c)]. Then, after removing the masking jig 15, the alumina containing a small amount of titanium oxide so as to cover the electrode layer 13 on the electrode layer 13 obtained in the second step, and thus on the lower insulating layer 12. (Material for forming the upper insulating layer) is plasma sprayed to form the upper insulating layer (dielectric layer) 14 [third step: see FIG. 4 (d)]. Finally, the electrostatic chuck is completed by subjecting the surface of the upper insulating layer 14 to sealing, grinding, and lapping in this order.
[0036]
As described above, this manufacturing method is characterized in that burrs are not formed at the edge of the electrode layer 13 during the manufacturing. That is, the material to be the electrode layer 13 is sprayed with the masking jig 15 having a special shape as described above disposed on the lower insulating layer 12. When thermal spraying is performed in this manner, the amount of deposited metal particles gradually decreases toward the jig body due to the action of the overhanging portion 15a, so that the edge of the electrode layer 13 is also tapered so that the thickness decreases toward the end. No burr is formed. Therefore, there was no problem caused by the presence of this burr, and it was obtained using this manufacturing method even when the thickness of the upper insulating layer 14 was small as in the first embodiment. The electrostatic chuck can exhibit excellent withstand voltage characteristics.
[0037]
【Example】
[Example 1]
As raw materials for the base, (1) 70 parts by weight of commercially available SiC powder (average particle size 66 μm) as a reinforcing material, and (2) a commercially available # 500 (average particle size 25 μm) as a reinforcing material. 30 parts by weight of SiC powder, (3) an appropriate amount of colloidal silica liquid serving as a binder (amount of silica solid content of 2 parts by weight), and (4) Formaster VL (manufactured by San Nopco) serving as an antifoaming material 2 parts by weight and (5) 24 parts by weight of ion-exchanged water were prepared, and these were mixed using a pot mill for 12 hours. Next, the slurry thus obtained is poured into a metal mold with a mesh (to obtain a disk-shaped molded body having a diameter of 350 mm and a thickness of 25 mm), subjected to a filter press, demolded, and fired at 1000 ° C. to perform a preform. Formed.
[0038]
Subsequently, an aluminum alloy (Al-12Si-3Mg-2Cu-3Ti) is impregnated in the preform in a nitrogen stream at 825 ° C. for 60 hours and then cooled. In this way, a base (length 209 mm, width 157 mm, thickness 10 mm) made of a metal-ceramic composite material with a SiC powder content of 65 vol% was produced.
[0039]
Next, in order to improve the adhesion, the surface of the base is subjected to blasting until the surface roughness is at least 5 μm or more in Rmax. Then, a 300 μm thick Al ₂ O ₃ layer, that is, a lower insulating layer is formed on the upper surface by plasma spraying. Thereafter, a Ni electrode layer having a thickness of 50 μm is further formed by plasma spraying in a rectangular specific region surrounded by the masking tape on the lower insulating layer.
[0040]
When the electrode layer is thus provided, the masking tape is peeled off and the edge thereof is polished into a taper shape using a diamond tool. Further, an Al ₂ O ₃ layer having a thickness of 400 μm, that is, an upper insulating layer is formed by plasma spraying so as to cover the electrode layer. Finally, a sealing process is performed using SiO ₂ metal alkoxide in vacuum, followed by grinding and lapping in order. The upper insulating layer has a thickness of 300 μm and a surface roughness Ra of 0.2 μm. The electrostatic chuck according to the present invention was manufactured.
[0041]
[Example 2]
An electrostatic chuck according to the present invention was fabricated basically in the same manner as in Example 1 except that a masking jig was used instead of the masking tape and the edge polishing was omitted when forming the electrode layer. did. The main dimension values of the masking jig are as follows.
Overhang length L: 2mm
Overhang thickness W: 2mm
Height of bottom surface of overhang (gap width) H: 2 mm
Overlap amount of overhang and electrode layer formation region U: 1mm
[0042]
[Comparative Example]
An electrostatic chuck for comparison was produced by a conventional method using a masking tape (however, polishing of the edge portion of the electrode layer was not performed). Other conditions are basically the same as in the first embodiment.
[0043]
[Evaluation]
With respect to the electrostatic chuck of Example 1 and Example 2 and the electrostatic chuck for comparison (Comparative Example), with a glass substrate having an ITO film disposed thereon, a DC voltage was applied up to 5 kV to withstand voltage. A test was conducted. Then, although the dielectric breakdown occurred in the comparative example at 1.5 kV, the dielectric breakdown did not occur until the end in Example 1 and Example 2, and it was confirmed that it had extremely excellent withstand voltage characteristics.
[0044]
【The invention's effect】
According to the present invention, it is possible to obtain an electrostatic chuck that exhibits excellent withstand voltage characteristics even when the thickness of the upper insulating layer is small.
[Brief description of the drawings]
FIG. 1 is a plan view of an electrostatic chuck according to a first embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the electrostatic chuck according to the first embodiment of the present invention taken along line XX in FIG. FIGS. 3A to 3E are schematic views showing a manufacturing procedure of an electrostatic chuck using the manufacturing method according to the first embodiment of the present invention. FIGS. FIG. 5 is a schematic view showing a manufacturing procedure of an electrostatic chuck using a manufacturing method according to a second embodiment of the invention. FIG. 5 is a perspective view of a masking jig shown in a partially broken state.
DESCRIPTION OF SYMBOLS 1,11 Base 2,12 Lower insulating layer 3,13 Electrode layer 3a Burr 4,14 of electrode layer Upper insulating layer (dielectric layer)
5 Masking tape 15 Masking jig 15a Masking jig overhang

Claims (3)

A base, a lower insulating layer formed on the upper surface of the base, an electrode layer formed on the lower insulating layer, and an upper portion formed on the lower insulating layer so as to cover the electrode layer A method for manufacturing an electrostatic chuck comprising an insulating layer,
A first step of spraying a material to be the lower insulating layer on the upper surface of the base;
A second step of thermally spraying a material to be the electrode layer on a region surrounded by a masking tape on the lower insulating layer obtained in the first step;
A third step of removing the masking tape and polishing the edge of the electrode layer obtained in the second step into a tapered shape;
After this third step is completed, a material to be the upper insulating layer is sprayed on the lower insulating layer so as to cover the electrode layer , and then the tapered edge of the electrode layer is covered. And a fourth step of polishing the surface of the upper insulating layer into a flat surface so that the thickness of the upper insulating layer increases toward the edge of the electrode layer. Method. A base, a lower insulating layer formed on the upper surface of the base, an electrode layer formed on the lower insulating layer, and an upper portion formed on the lower insulating layer so as to cover the electrode layer A method for manufacturing an electrostatic chuck comprising an insulating layer,
A first step of spraying a material to be the lower insulating layer on the upper surface of the base;
An overhang projecting above the electrode layer forming region so that a gap is formed between the electrode layer forming region on the surface of the lower insulating layer when placed on the lower insulating layer obtained in the first step. A second step of thermally spraying a material to be the electrode layer on the lower insulating layer in a state where the masking jig provided with is disposed on the lower insulating layer;
The upper insulating layer is sprayed with a material to be the upper insulating layer so as to cover the electrode layer obtained in the second step, and then the upper edge portion covering the tapered edge of the electrode layer. And a third step of polishing the surface of the upper insulating layer into a flat surface so that the thickness of the insulating layer increases toward the edge of the electrode layer . An electrostatic chuck obtained by using the method for manufacturing an electrostatic chuck according to claim 1 or 2,
A base, a lower insulating layer formed on the upper surface of the base by thermal spraying, an electrode layer formed on the lower insulating layer, and thermal spraying on the lower insulating layer to cover the electrode layer An upper insulating layer formed, and the edge of the electrode layer is tapered, and the thickness of the upper insulating layer covering the tapered edge of the electrode layer is the edge of the electrode layer. An electrostatic chuck , wherein the surface of the upper insulating layer is formed in a planar shape .

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