JP2002170869A - Electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large and thin electrostatic chuck with good thermal response property. SOLUTION: The chuck comprises a stainless steel material 1, an insulation layer 2 comprised of crystallized glass formed on the surface of the stainless steel material 1, an electrode 3 spreading with a pattern on the surface of the insulation layer 2, and a dielectric layer 4 covering the surface of the electrode 3. The substrate that mounted on the surface of the dielectric layer 4 is chucked with positive or negative electrostatic charge generated on the surface of the dielectric layer 4 by applying direct current potential to the electrode 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck particularly used for fixing a silicon wafer or the like in a semiconductor manufacturing apparatus or the like.

[Prior art]

[0002] An electrostatic chuck in which a thin electrode made of a conductive material such as tungsten is embedded in a ceramic material such as aluminum oxide or aluminum nitride having excellent heat resistance and corrosion resistance is used in an etching apparatus such as a semiconductor wafer or a CVD apparatus. Is used as a mechanism for adsorbing and holding by electrostatic attraction (Coulomb force). The electrostatic chuck 13 shown in FIG. 2 prints a paste-like material obtained by mixing tungsten, alumina, a solvent, and a binder, which become the electrode 12, on a rectangular ceramic green sheet 11a, which becomes a dielectric film. The ceramic green sheets 11b having a rectangular shape are thermocompressed and sequentially laminated, and then cut into a circular shape. Thereafter, by firing in a reducing atmosphere furnace, the electrostatic chuck 13 having the electrodes embedded in the ceramic material is formed.
Is produced.

[0003]

In recent years, a large and thin electrostatic chuck has been desired in order to improve the production efficiency of wafers. However, an electrostatic chuck in which electrodes are embedded in a ceramic material has the properties of ceramic (brittle due to low fracture toughness, low machinability, etc.) and manufacturing (lamination of ceramic green sheets, shrinkage during firing, etc.)
Moreover, it is unsuitable for a thin, large size. In addition, when cooling a wafer heated to a high temperature by etching or the like through an electrostatic chuck, if cold water or cold air comes into direct contact with the ceramic material surface, cracks occur because the cold resistance of the ceramic material is low. There is a possibility that the electrode is disconnected and the adsorption performance is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a large and thin electrostatic chuck having good thermal responsiveness.

[0005]

Means for Solving the Problems and Action / Effect In order to solve the above problems, the invention according to claim 1 comprises a stainless steel, an insulating layer made of crystallized glass formed on the surface of the stainless steel, An electrode that spreads in a pattern on the surface of the insulating layer; and a dielectric layer that covers the surface of the electrode. A positive or negative electrostatic charge is generated on the surface of the dielectric layer by applying a DC voltage to the electrode. An electrostatic chuck for adsorbing a substrate placed on the surface of the dielectric layer. By sequentially forming an insulating layer, an electrode, and a dielectric layer made of crystallized glass on the surface of a stainless steel having a stable shape, there is almost no change in shape due to shrinkage, and the size can be increased. In addition, since sufficient mechanical strength can be obtained in production and use by using a stainless steel material, the thickness of the insulating layer and the dielectric layer can be reduced to a level that satisfies the insulation / adsorption performance. Therefore, the thermal responsiveness can be improved, and the surface temperature of the electrostatic chuck can be accurately adjusted. If the thickness of the stainless steel material is to be made smaller than the sum of the thicknesses of the insulating layer and the dielectric layer in order to further improve the thermal responsiveness, the other surface on which the stainless steel insulating layer, electrode, and dielectric layer are not formed (hereinafter referred to as the back surface) ), A stress relaxation layer having a thickness obtained by adding the thicknesses of the insulating layer and the dielectric layer is formed of the same material as the insulating layer, thereby preventing the warpage of the stainless steel material and insulating due to cracking of the insulating layer and the dielectric layer. It is possible to prevent poor suction and defective suction due to electrode disconnection. Then, when cooling the wafer heated to a high temperature by etching or the like via an electrostatic chuck, even if cold water or cold air is directly in contact with the back surface of the stainless steel material, the wafer is cooled without disturbing the insulating layer and the dielectric layer. be able to.

According to a second aspect of the present invention, the insulating layer, the electrode, and the dielectric layer are formed by screen printing. An insulating layer, an electrode, and a dielectric layer can be accurately formed at an arbitrary position, and the thickness of the insulating layer and the dielectric layer can be reduced by one.
Adjustment can be made at the 0 μm level. Therefore, since the insulating layer and the dielectric layer can be formed in a required thickness, the thickness can be easily reduced according to the specification. Further, since an insulating layer, an electrode, and a dielectric layer can be formed on a stainless steel material that has been previously formed into a circular shape, there is no need to process the product into a circular shape after printing, and production defects such as peeling and cracking do not occur. When it is desired to form an insulating layer, an electrode, and a dielectric layer with high precision, one or more notches for printing positioning may be provided on the end face of the stainless steel material, and the notches may be fixed to the printing press using the notches. Further, since irregularities of several tens of μm can be easily provided at an arbitrary position on the surface of the dielectric layer on which the substrate (wafer) is mounted, the coefficient of friction between the substrate and the dielectric layer is reduced, and the desorption performance is improved. be able to.

The invention according to claim 3 is characterized in that the dielectric layer contains alumina. By mixing alumina particles in the dielectric layer, the dielectric constant increases, and the adsorption performance can be improved, so that a further reduction in thickness can be achieved. The content ratio of the alumina particles is preferably about several% to 20% in consideration of the adhesion to the insulating layer and the electrode.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the electrostatic chuck according to the present invention will be described below in detail with reference to the drawings. The electrostatic chuck 5 shown in FIG. 1 has, on the surface of a stainless steel material 1, a crystallized glass having the same thermal expansion coefficient as that of the stainless steel material 1 as a main component, an insulating layer 2 having a thickness of about 200 μm, and silver as a main component. An electrode 3 having a thickness of about 10 μm by mixing several percent of glass frit,
A dielectric layer 4 having a thickness of about 400 μm is formed by mixing about 10% of alumina particles with crystallized glass as a main component. In the drawings described in the present embodiment, the thickness of each member is different from the actual thickness.

[0009] Stainless steel is SUS3, which has excellent corrosion resistance.
04, SUS444 or those containing alumina are preferable, and the thickness thereof is 2 mm in consideration of thermal responsiveness and manufacturability.
And If you want to make the thickness of stainless steel thinner than the sum of the thickness of the insulating layer and the thickness of the dielectric layer with emphasis on thermal response,
For example, when the thickness of the stainless material is 0.4 mm, the thickness of the insulating layer is 200 μm, and the thickness of the dielectric layer is 400 μm, the insulating layer, the electrode, and the dielectric layer are not formed. By forming a stress relaxation layer having a thickness of about 600 μm, which is the sum of the thicknesses of the layers, from the same material as the insulating layer, the warpage of the stainless steel material is prevented, insulation failure due to cracks in the insulating layer and the dielectric layer, insulation failure of the electrode, Adsorption failure due to disconnection can be prevented. The mounting to the semiconductor device can be easily performed by providing one or more fixing through holes in the outer periphery or an arbitrary position of the stainless steel material in advance, or by connecting the fixing screws to the back surface of the stainless steel material by welding.

[0010] The stainless steel material 1
The paste material mainly composed of crystallized glass having the same coefficient of thermal expansion is printed by screen printing, pre-dried at 150 ° C., and then fired at 850 ° C. in the air, so that the adhesiveness to the stainless steel material 1 and heat resistance The insulating layer 2 having excellent properties is formed.

The surface of the insulating layer 2 is printed with a paste material containing silver as a main component and a glass frit of several percent by screen printing, pre-dried at 150 ° C., and then fired at 850 ° C. in the air to obtain an arbitrary pattern. Is formed. If necessary, by mixing palladium with silver in a range of several percent to 50%, the heat resistance can be improved and the temperature coefficient of resistance can be reduced, so that a change in the resistance value between normal temperature and high temperature can be suppressed. , Controllability is improved.

A paste material containing crystallized glass as a main component and containing about 10% of alumina particles is printed by screen printing so as to cover the surface of the electrode 3, and is preliminarily dried at 150 ° C. and then fired at 850 ° C. in the air. Thus, the dielectric layer 4 is formed. By changing and printing the printing pattern between the electrode contact surface and the surface of the dielectric layer on which the substrate (wafer) is mounted, irregularities of several tens of μm can be easily provided at arbitrary positions.

With this configuration, the insulating layer 2, the electrode 3, and the dielectric layer 4 made of crystallized glass are sequentially formed on the surface of the stainless steel 1 having a stable shape, so that the shape is hardly changed due to shrinkage, and the size is large. Can be achieved. In addition, since the use of the stainless steel material 1 provides sufficient mechanical strength in production and use, the insulating layer 2
In addition, the thickness of the dielectric layer 4 can be reduced so as to satisfy the insulation / adsorption performance. Therefore, the thermal responsiveness can be improved, and the surface temperature of the electrostatic chuck 5 can be accurately adjusted. When the wafer heated to a high temperature by etching or the like is cooled via the electrostatic chuck 5, even if cold water or cold air is in direct contact with the back surface of the stainless steel material 1, the insulating layer 2 and the dielectric layer 4 are hindered. It can be cooled without. Furthermore, by forming a heater circuit on the lower layer of the electrode or on the back surface of the stainless steel through an insulating layer, the electrostatic chuck can be heated quickly and uniformly, so that the wafer adsorbed on the surface of the dielectric layer can be heated. It is also possible to adjust the temperature to any temperature.

Further, the present invention is not limited to the above-mentioned examples and embodiments at all, and it is needless to say that the present invention can be implemented in various modes without departing from the gist of the present invention. For example, using an electrophoresis method, a crystallized glass can be applied to the entire surface of stainless steel, dried and sintered to form an insulating layer, and an electrode and a dielectric layer can be formed on the surface. Similar effects can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an electrostatic chuck according to the present invention.

FIG. 2 is a cross-sectional view illustrating a schematic configuration of an electrostatic chuck described in the related art.

[Explanation of symbols]

1: stainless steel, 2: insulating layer, 3: electrode (silver), 4:
Dielectric layer, 5: electrostatic chuck (the present invention), 11 (11a,
11b): ceramic green sheet, 12: electrode (tungsten), 13: electrostatic chuck (prior art)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takahiro Ohashi 2-1-1 Nakajima, Kokurakita-ku, Kitakyushu-shi, Fukuoka F-term (reference) in TOTO Kiki Co., Ltd. 3C016 GA10 5F031 CA02 HA02 HA03 HA16 PA18

Claims (3)

[Claims] 1. A stainless steel material, an insulating layer made of crystallized glass formed on the surface of the stainless steel material, an electrode extending in a pattern on the insulating layer surface, and a dielectric layer covering the electrode surface. Applying a DC voltage to the electrode to generate a positive or negative electrostatic charge on the surface of the dielectric layer and attracting a substrate mounted on the surface of the dielectric layer. . 2. The method according to claim 1, wherein the insulating layer, the electrode, and the dielectric layer are formed by screen printing.
An electrostatic chuck as described. 3. The electrostatic chuck according to claim 1, wherein the dielectric layer contains alumina.