JP2002289676A - Electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic chuck which is highly excellent in adhesion between an electric conductor or a base and an insulation layer. SOLUTION: Concerning the electrostatic chuck covering the surface of the electric conductor or the base with the insulation layer, the electric conductor or the base is a low thermal expansion alloy and the insulation layer is ceramic.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrostatic chuck, and more particularly, to an electrostatic chuck made of a low thermal expansion alloy.

[0002]

2. Description of the Related Art Electrostatic chucks have recently been widely used as components of semiconductor manufacturing equipment and the like. The reason is considered to be that merits such as less dust generation and use even in a vacuum have been recognized as compared with mechanical chucking and vacuum chucks.

As this electrostatic chuck, a rigid one made of ceramics or the like has begun to be used. However, since it is expensive, an insulating material such as an alumina sprayed layer is formed on the surface of a conductor or a base made of an aluminum alloy or the like. The simple thing which just covered the layer is the mainstream.

[0004]

However, in the electrostatic chuck made of this aluminum alloy, there is a problem that the insulating layer does not adhere strongly due to a large difference in thermal expansion between the aluminum alloy and the insulating layer such as an alumina sprayed layer. there were. For this reason, the insulating layer has been separated from the aluminum alloy.

The present invention has been made in view of the above-mentioned problems of the electrostatic chuck, and an object of the present invention is to provide an electrostatic chuck having extremely excellent adhesion between a conductor or a base and an insulating layer. It is in.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, if the conductor or the base is made of a conductor or a base made of a low thermal expansion alloy, the upper surface thereof is covered. The present invention was completed based on the finding that an electrostatic chuck having extremely excellent adhesion to an insulating layer to be obtained was obtained.

That is, the present invention provides (1) an electrostatic chuck comprising a conductor surface coated with an insulating layer, wherein the conductor is made of a low thermal expansion alloy, and the insulating layer is made of a ceramic layer. An electrostatic chuck (Claim 1)
(2) In an electrostatic chuck in which an insulating layer in which an electrode is formed on the upper surface of a base is coated, the base is made of a low thermal expansion alloy, and the insulating layer is made of a ceramic layer. A characteristic electrostatic chuck (claim 2);
(3) The electrostatic chuck according to (1) or (2), wherein the low thermal expansion alloy has a linear thermal expansion coefficient equal to that of the insulating layer. (4) The low thermal expansion alloy. Is made of an Fe—Ni—Mn-based alloy, and the gist of the invention is to provide an electrostatic chuck according to claims 1 to 3 (claim 4). This will be described in more detail below.

In the above-mentioned electrostatic chuck, the conductor is made of a low thermal expansion alloy, and the insulating layer is made of a ceramic layer.

As another electrostatic chuck, the base is made of a low thermal expansion alloy, and the insulating layer is made of a ceramic layer (claim 2).

As described above, the conductor or base constituting the electrostatic chuck is made of a low thermal expansion alloy, so that the difference in thermal expansion between the conductor and the insulating layer formed on the surface or the upper surface can be reduced. Because.

The coefficient of linear thermal expansion of the low thermal expansion alloy is the same as that of the insulating layer. It is difficult to match the coefficient of linear thermal expansion with the insulating layer with aluminum alloy,
Regarding the low thermal expansion alloy of the present invention, a considerable range of linear thermal expansion coefficient can be selected by selecting the type and composition of the low thermal expansion alloy, so that the low thermal expansion alloy and the insulating layer have the same linear thermal expansion coefficient. , Or approximately equivalent. By making the linear thermal expansion coefficients of the low thermal expansion alloy and the insulating layer equal or substantially equal, the obstacle due to the difference in thermal expansion is reduced, which is particularly preferable.

[0012] As a kind of the low thermal expansion alloy, Fe-
A Ni-Mn alloy was used (claim 4). Any alloy may be used as long as the coefficient of linear thermal expansion is lower than that of an aluminum alloy. Among them, an Fe-Ni-Mn alloy having a linear thermal expansion coefficient close to that of a ceramic layer is particularly preferable.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The manufacturing method of the present invention will be described. First, a low thermal expansion alloy made of an Fe-Ni-Mn system is prepared. Grind the surface of the prepared low thermal expansion alloy so that it has the required surface roughness and flatness so that it adheres well, and form an insulating layer consisting of a ceramic layer such as alumina on the upper surface by spraying to form an electrostatic chuck. Is prepared.

On the other hand, when the low-thermal-expansion alloy is used as a base, the surface of the prepared low-thermal-expansion alloy is ground so as to have the necessary surface roughness and flatness so as to adhere well as before,
An insulating layer made of a ceramic layer such as alumina is formed on the upper surface by spraying, an electrode made of tungsten is formed on the upper surface by plasma spraying, and an insulating layer formed of a ceramic layer such as alumina is formed on the upper surface by spraying. Then, an electrostatic chuck is manufactured.

The thickness of the insulating layer to be formed is 100 to 500.
If the thickness is less than 100 μm, the withstand voltage is low and dielectric breakdown is likely to occur. Adsorption power also decreases. The most common type of ceramic layer that is an insulating layer is
Alumina is not limited to alumina, but if necessary characteristics such as a high dielectric constant are required, the type of ceramic may be appropriately selected according to the required dielectric constant.

If an electrostatic chuck is manufactured by the above method,
An electrostatic chuck having excellent adhesion between the conductor or the base and the insulating layer can be obtained.

[0017]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples of the present invention and Comparative Examples.

Example 1 (1) Production of Electrostatic Chuck Fe--Ni--Mn based composition as an electric conductor was 63.385.
Using a low thermal expansion alloy made of Fe-36.00Ni-0.25Mn (linear thermal expansion coefficient: 6.5 to 7.5 × 10 ⁻⁶ / ° C.), a disc of φ300 × t30 mm was prepared from the alloy, and the surface thereof was well formed. The surface roughness is 5μ at Rmax for close contact
m with a # 80 diamond grindstone until
An Al ₂ O ₃ layer (linear thermal expansion coefficient: 7.8 × 10 ⁻⁶ / ° C.) was formed to a thickness of 200 μm on the upper surface by plasma spraying to produce an electrostatic chuck.

(2) Evaluation A DC voltage of 3 kV was applied to the obtained electrostatic chuck,
It was examined whether or not the l ₂ O ₃ layer was in close contact. as a result,
Discharge between the conductor and the Al ₂ O ₃ layer even by applying a DC voltage is not generated, Razz observed breakdown of the Al ₂ O ₃ layer, Al ₂
The O ₃ layer was firmly adhered.

(Embodiment 2) The low thermal expansion alloy used in Embodiment 1 was used as a base. In order to make the surface of the low thermal expansion alloy adhere well, the surface roughness was reduced to # 80 until the surface roughness became 5 μm or more in Rmax.
Of ground with a diamond grindstone to form a the Al ₂ O ₃ layer by plasma spraying on the upper surface to a thickness of 200 [mu] m, to form an electrode made of tungsten plasma spraying on the top surface thereof, further Al ₂ by plasma spraying on the upper surface 200 μm O ₃ layer
To form an electrostatic chuck. The obtained electrostatic chuck was evaluated in the same manner as in Example 1. As a result, even when applying the same DC voltage as in Example 1 does not occur in discharge between the conductor and the Al ₂ O ₃ layer, Razz observed breakdown of the Al ₂ O ₃ layer, Al ₂ O ₃ The layers were tightly adhered. This means
The description including Example 1 indicates that the electrostatic chuck of the present invention has extremely excellent adhesion of the insulating layer to the conductor or the base.

(Comparative Example 1) (1) Production of Electrostatic Chuck Except that an aluminum alloy (linear thermal expansion coefficient: 12.9 × 10 ⁻⁶ / ° C.) was used instead of the low thermal expansion alloy used in Example 1. An electrostatic chuck was manufactured and evaluated in the same manner as in Example 2. As a result, the Al ₂ O ₃ layer was separated from the base due to dielectric breakdown while increasing the voltage.

[0022]

As described above, with the electrostatic chuck according to the present invention, an electrostatic chuck having extremely excellent adhesion between the conductor or the base and the insulating layer can be obtained. As a result, it has become possible to provide an excellent electrostatic chuck in which the insulating layer does not peel off.

Claims (4)

[Claims] 1. An electrostatic chuck comprising a conductor surface coated with an insulating layer, wherein the conductor is made of a low thermal expansion alloy, and the insulating layer is made of a ceramic layer. 2. An electrostatic chuck comprising an insulating layer having an electrode formed on the upper surface of a base, wherein the base is made of a low thermal expansion alloy, and the insulating layer is made of a ceramic layer. An electrostatic chuck characterized in that: 3. The electrostatic chuck according to claim 1, wherein the low thermal expansion alloy has a linear thermal expansion coefficient equal to that of the insulating layer. 4. The low thermal expansion alloy comprises Fe—Ni—Mn.
4. The electrostatic chuck according to claim 1, wherein the electrostatic chuck is made of a system alloy.