阅读说明：本技术 静电卡盘 (Electrostatic chuck ) 是由 竹林央史 相川贤一郎 久野达也 于 2020-06-10 设计创作，主要内容包括：静电卡盘具备陶瓷基材、陶瓷电介质层、静电电极和陶瓷绝缘层。陶瓷电介质层配置在陶瓷基材上,比陶瓷基材薄。静电电极埋设在陶瓷电介质层与陶瓷基材之间。陶瓷绝缘层配置在陶瓷电介质层上,比陶瓷电介质层薄。陶瓷绝缘层的体积电阻率及耐电压比所述陶瓷电介质层高,陶瓷电介质层的介电常数比陶瓷绝缘层高。(The electrostatic chuck includes a ceramic base, a ceramic dielectric layer, an electrostatic electrode, and a ceramic insulating layer. The ceramic dielectric layer is disposed on the ceramic substrate and is thinner than the ceramic substrate. The electrostatic electrode is embedded between the ceramic dielectric layer and the ceramic substrate. The ceramic insulating layer is disposed on the ceramic dielectric layer and is thinner than the ceramic dielectric layer. The volume resistivity and withstand voltage of the ceramic insulating layer are higher than those of the ceramic dielectric layer, and the dielectric constant of the ceramic dielectric layer is higher than that of the ceramic insulating layer.)

1. An electrostatic chuck is provided with:

a ceramic substrate;

a ceramic dielectric layer disposed on the ceramic substrate and thinner than the ceramic substrate;

an electrostatic electrode embedded between the ceramic dielectric layer and the ceramic substrate; and

a ceramic insulating layer disposed on the ceramic dielectric layer and thinner than the ceramic dielectric layer,

the ceramic insulating layer has a higher volume resistivity and higher withstand voltage than the ceramic dielectric layer,

the dielectric constant of the ceramic dielectric layer is higher than that of the ceramic insulating layer.

2. The electrostatic chuck of claim 1, wherein the ceramic insulating layer is an aerosol deposited film or a sputtered film.

3. The electrostatic chuck according to claim 1 or 2, wherein the ceramic dielectric layer is made of barium titanate or lead zirconate titanate, and the ceramic insulating layer is made of alumina.

4. The electrostatic chuck of any one of claims 1 to 3, wherein the ceramic insulating layer is provided so as to cover the entire surface of the ceramic dielectric layer, having a plurality of convex portions that support a wafer.

5. The electrostatic chuck of any of claims 1 to 3, wherein the ceramic dielectric layer has a plurality of protrusions supporting a wafer, the ceramic insulating layer being disposed at least on top surfaces of the protrusions.

Technical Field

The present invention relates to electrostatic chucks.

Background

Conventionally, an electrostatic chuck for holding a wafer by suction has been used in a film formation process such as transfer, exposure, or CVD of a semiconductor wafer, or in microfabrication such as cleaning, etching, or dicing. For example, an electrostatic chuck disclosed in patent document 1 includes: a ceramic substrate, a thin ceramic dielectric layer disposed on the ceramic substrate, and an electrostatic electrode embedded between the ceramic dielectric layer and the ceramic substrate (see fig. 4). The surface of the ceramic dielectric layer is a wafer mounting surface. In the electrostatic chuck, the material of the ceramic base material and the material of the ceramic dielectric layer are both alumina sintered bodies.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-343733

Disclosure of Invention

Problems to be solved by the invention

However, since the ceramic dielectric layer is made of an alumina sintered body, the dielectric constant is not so high although the insulating performance (volume resistivity, withstand voltage) is high. Therefore, the electrostatic attraction force for attracting the wafer to the wafer mounting surface may not be sufficiently obtained.

The present invention has been made to solve the above problems, and a main object thereof is to provide an electrostatic chuck having high insulating performance and electrostatic adsorption force.

Means for solving the problems

The electrostatic chuck of the present invention comprises:

a ceramic substrate;

a ceramic dielectric layer disposed on the ceramic substrate and thinner than the ceramic substrate;

an electrostatic electrode embedded between the ceramic dielectric layer and the ceramic substrate; and

a ceramic insulating layer disposed on the ceramic dielectric layer and thinner than the ceramic dielectric layer,

the ceramic insulating layer has a higher volume resistivity and higher withstand voltage than the ceramic dielectric layer,

the dielectric constant of the ceramic dielectric layer is higher than that of the ceramic insulating layer.

In this electrostatic chuck, since the volume resistivity and withstand voltage of the ceramic insulating layer are higher than those of the ceramic dielectric layer, the insulating performance is maintained high by the ceramic insulating layer. On the other hand, since the dielectric constant of the ceramic dielectric layer is higher than that of the ceramic insulating layer, the electrostatic attraction force which becomes higher in proportion to the dielectric constant becomes higher by the ceramic dielectric layer. Thus, the electrostatic chuck of the present invention has high insulating performance and electrostatic adsorption force.

In the electrostatic chuck of the present invention, the ceramic insulating layer may also be an Aerosol Deposition (AD) film or a sprayed film. The ceramic insulating layer is particularly preferably an AD film. In the AD film, a glass phase having low insulation is not present in the grain boundaries between the raw material particles, and the volume resistivity and withstand voltage are high because the AD film is comparable to a film obtained by sintering the raw material particles.

In the electrostatic chuck according to the present invention, the material of the ceramic dielectric layer is preferably barium titanate or lead zirconate titanate, and the material of the ceramic insulating layer is preferably alumina.

In the electrostatic chuck according to the present invention, the ceramic insulating layer may be provided so as to cover the entire surface of the ceramic dielectric layer, and may have a plurality of projections for supporting a wafer.

In the electrostatic chuck of the present invention, the ceramic dielectric layer may have a plurality of projections for supporting a wafer, and the ceramic insulating layer may be provided at least on top surfaces of the projections. In the ceramic insulating layer, the ceramic insulating layer may cover the entire surface of the ceramic dielectric layer instead of only the convex portion of the ceramic dielectric layer.

Drawings

Fig. 1 is a longitudinal sectional view of the electrostatic chuck of the present embodiment.

Fig. 2 is a longitudinal sectional view of an electrostatic chuck according to another embodiment.

Fig. 3 is a longitudinal sectional view of an electrostatic chuck according to another embodiment.

Fig. 4 is a longitudinal sectional view of a conventional electrostatic chuck.

Detailed Description

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Fig. 1 is a process diagram (vertical sectional view) of manufacturing a wafer stage.

As shown in fig. 1, the electrostatic chuck includes a ceramic base, a ceramic dielectric layer, an electrostatic electrode, and a ceramic insulating layer. The ceramic dielectric layer is disposed on the ceramic substrate and is thinner than the ceramic substrate. In the present embodiment, the ceramic dielectric layer and the ceramic base material are a ceramic sintered body that is integrally sintered. The electrostatic electrode is embedded between the ceramic dielectric layer and the ceramic substrate. The ceramic insulating layer is disposed on the ceramic dielectric layer and is thinner than the ceramic dielectric layer. The volume resistivity and withstand voltage of the ceramic insulating layer are higher than those of the ceramic dielectric layer, and the dielectric constant of the ceramic dielectric layer is higher than that of the ceramic insulating layer.

The ceramic insulating layer may be a CVD film or a PVD film, but is preferably an AD film or a thermal spray film in terms of being able to relatively easily increase the film thickness. In particular, in the AD film, a glass phase having low insulation is not present in the grain boundaries between the raw material particles, and the volume resistivity and withstand voltage are increased as much as those of a film obtained by sintering the raw material particles. The AD film is a film formed by an AD method (including a plasma AD method). The AD method can form ceramic particles into a film by an impact curing phenomenon, and thus it is not necessary to sinter the ceramic particles at a high temperature.

The material of the ceramic dielectric layer is preferably barium titanate or lead zirconate titanate, and the material of the ceramic insulating layer is preferably alumina.

In the electrostatic chuck according to the present embodiment described above, since the volume resistivity and withstand voltage of the ceramic insulating layer are higher than those of the ceramic dielectric layer, the insulating performance is maintained high by the ceramic insulating layer. On the other hand, since the dielectric constant of the ceramic dielectric layer is higher than that of the ceramic insulating layer, the electrostatic attraction force which becomes higher in proportion to the dielectric constant becomes higher by the ceramic dielectric layer.

It should be noted that the present invention is not limited to the above-described embodiments, and can be implemented in various forms as long as the present invention falls within the technical scope of the present invention.

For example, in the above-described embodiment, the ceramic insulating layer may be provided so as to cover the entire surface of the ceramic dielectric layer and may have a plurality of projections for supporting the wafer (see fig. 2). In such a structure, for example, an AD film may be formed so as to cover the entire surface of the ceramic dielectric layer, the surface of the AD film may be finished to a mirror surface (for example, a surface having a surface roughness Ra of 0.1 μm or less), and then a plurality of projections may be formed on the mirror surface by an AD method (including a plasma AD method). In this way, the portion where the convex portion is not formed remains in a mirror surface state, and thus does not cause generation of particles in a semiconductor process.

In the above-described embodiment, the ceramic dielectric layer may have a plurality of projections for supporting the wafer, and the ceramic insulating layer may be provided only on the top surfaces of the projections (see fig. 3), but from the viewpoint of improving the withstand voltage, it is preferable to cover the entire surface of the ceramic dielectric layer, not only the projections of the ceramic dielectric layer.

In the above-described embodiment, at least one of the RF electrode and the heater electrode (resistance heating element) may be embedded in the ceramic substrate.

The present application takes japanese patent application No. 2019-121488, filed on 6/28/2019, as the basis of priority claims, the entire contents of which are incorporated by reference in the present specification.

Industrial applicability of the invention

The present invention can be used for film formation processes such as transfer, exposure, and CVD of semiconductor wafers, and for microfabrication such as cleaning, etching, and dicing.