JP3956620B2

JP3956620B2 - Electrostatic chuck

Info

Publication number: JP3956620B2
Application number: JP2001007122A
Authority: JP
Inventors: 清川畑; 潔川合; 計二佐藤; 勇治小笠原
Original assignee: Hitachi Chemical Co Ltd; Showa Denko Materials Co Ltd; Resonac Corp
Current assignee: Resonac Corp
Priority date: 2001-01-16
Filing date: 2001-01-16
Publication date: 2007-08-08
Anticipated expiration: 2021-01-16
Also published as: JP2002217277A

Description

【０００１】
【発明の属する技術分野】
本発明は、半導体デバイス製造装置、液晶デバイス製造装置等の半導体・液晶分野に用いられる静電チャック、特に双極型の静電チャックに関する。
【０００２】
【従来の技術】
半導体デバイスや液晶デバイスを製造する際、特に真空雰囲気においてはシリコンウェーハ、ガラス基板等を保持するために、従来のメカクランプ方式から、面吸着が可能な静電チャックが検討されている。
静電チャックを構成する誘電体材料は、厚さと電極面積で決まる固有の抵抗値を有しており、吸着時に数百Ｖ以上の電圧を印加すると誘電体の固有抵抗に応じた漏れ電流が流れる。
【０００３】
正負一対の電極を有する双極型の静電チャックは、被吸着物にアースの接続が生じないため、装置の機構が簡単になる利点を有するが、従来の双極型の静電チャックは、一枚の誘電体に一対の電極を形成しており、誘電体材料の厚さと電極面積で決まる固有の抵抗値に起因する電流の他に、電極間で電極間隔と対抗電極間の縁長さで決まるいわゆる表面電流が流れる。
【０００４】
表面電流は数μＡであっても、例えば電子線を用いた装置のように微少な電磁界の影響を受ける装置では無視できない。特開平１１−１６３１１０号公報などに示されるような絶縁基板を裏面の導体膜を介して吸着するような液晶ガラス用の静電チャックでは高電圧を印加することにより表面電流が数ｍｍＡ以上になり、そのため高電流容量の高価な電源が必要となり、双極型の静電チャックでは表面電流の低減が望まれていた。
【０００５】
【発明が解決しようとする課題】
請求項１記載の発明は、誘電体に形成される電極間の誘電体の表面電流を著しく低減する静電チャックを提供するものである。
【０００６】
【課題を解決するための手段】
本発明は、絶縁体からなる基体と複数個の誘電体を有し、かつ各々の誘電体に電圧印加電極が形成され、さらに誘電体と隣接する誘電体の間に、誘電体の表面抵抗より高い抵抗を有する前記基体と同一材料の絶縁体を介在させてなる静電チャックに関する。また、前記誘電体と隣接する誘電体の間に介在され、該誘電体の表面抵抗より高い抵抗を有する絶縁体が、基体となる絶縁体と一体であることを特徴とする。しかも、前記誘電体がＳｉＣであり、前記絶縁体がＡｌ _２Ｏ _３であることを特徴とする。
【０００７】
【発明の実施の形態】
本発明の静電チャックに用いられる誘電体の材料としては、Ａｌ₂Ｏ₃、Ｓｉ₃Ｎ₄、ＡｌＮ、ＳｉＣ、ＢａＴｉＯ₃等のセラミックス材料が用いられる。
誘電体に形成する電圧印加電極としては、Ａｇ−Ｐｄ、Ｗ、Ａｇ、Ａｕ等の金属を含むガラスペーストを焼き付けたり、Ａｌ、Ｃｕ、ＳＵＳ等の金属板又は金属箔を密着させて形成することができる。
【０００８】
基体となる絶縁体及び誘電体と隣接する誘電体の間に介在させる該誘電体の表面抵抗より高い抵抗を有する絶縁体に用いられる絶縁材料は、絶縁破壊電圧が大きく、絶縁抵抗の高い、高純度Ａｌ₂Ｏ₃（純度９０％以上）、ＳｉＯ₂等が用いられる。なお、誘電体と隣接する誘電体の間に該誘電体の表面抵抗より高い抵抗を有する絶縁体に用いられる絶縁材料は、誘電体より１０倍以上体積固有抵抗の高い材料を用いることが好ましく、５０倍以上であればより好ましく、上限については特に制限はない。
【０００９】
誘電体と隣接する誘電体の間に該誘電体の表面抵抗より高い抵抗を有する絶縁体に用いられる誘電材料は、基体となる絶縁体と一体でも差し支えない。なお、吸着面は単極構造の誘電体表面より出張ると吸着時に誘電体と吸着物の間に隙間が生じ、所望の吸着力が得られないので同時研磨するなどして少なくとも面一に加工することが好ましい。
【００１０】
以下、本発明の実施の形態を図面を引用して説明する。
図1は本発明の原理的構成を説明する静電チャックの断面図、図２はその電気的等価回路を示す図、図３は本発明の実施例になる静電チャックの要部を示す斜視図、図４は図３のＡ−Ａ線断面図、図５は従来の原理的構成を説明する静電チャックの断面図、図６はその電気的等価回路を示す図、図７は従来の静電チャックの要部を示す斜視図、図８は図７のＢ−Ｂ線断面図及び図９は漏れ電流を測定するための測定回路を示す図であり、１は誘電体、２は絶縁体、３は電圧印加電極、４は被吸着物、５はＳｉＣ及び６は高純度Ａｌ₂Ｏ₃である。
【００１１】
図１に示す本発明の静電チャックは図５に示す従来の静電チャックで生じる誘電体１の表面抵抗Ｒｓに起因するの表面電流を絶縁体２の大きな抵抗Ｒｚ（Ｒｚ＞Ｒｓ）を介在させることにより低減できる。また絶縁体２の抵抗値Ｒｚを誘電体１の表面抵抗Ｒｓよりも甚だ大きくすれば（Ｒｚ》Ｒｓ）誘電体１の表面抵抗Ｒｓに起因する表面電流を遮断することもできる。
【００１２】
以下、本発明を実施例により説明するが、本発明はこれに制限されるものではない。
実施例１
図３に示すように、誘電体として体積固有抵抗が1×10⁹Ωｍで、寸法が６６ｍｍ×２４．５ｍｍ×厚さ２ｍｍのＳｉＣ(日立化成工業（株）製、商標名ヘキサロイ) ５を二枚及び絶縁体として体積固有抵抗が1×10¹⁴Ωｍで、寸法が１００ｍｍ×１００ｍｍ×厚さ１０ｍｍの高純度Ａｌ₂Ｏ₃ (日立化成工業（株）製、商標名ハロックス)６を一枚用い、ＳｉＣ（誘電体）５の片側全面に速乾性導電ペースト(徳力化学製、商標名シルベスト)を塗布し、自然乾燥して厚さが２０μｍの電圧印加電極３を形成した。
【００１３】
この後、図４に示すように、高純度Ａｌ₂Ｏ₃ (絶縁体)６の片側面に前記のＳｉＣ（誘電体）５を埋め込むための窪みを設け、さらに該窪みの底部から反対側の表面に貫通する電圧印加電極用孔７を形成し、しかる後前記窪みの部分にＳｉＣ（誘電体）５に形成した電圧印加電極３を下側に向けて挿入し、窪みと電圧印加電極３とを絶縁性エポキシ接着剤(チバガイギー社製、商標名アラルダイト)で接着し、次いでＳｉＣ（誘電体）５と高純度Ａｌ₂Ｏ₃(絶縁体)６の両表面を同時に研磨して吸着面を面一とした、ＳｉＣ（誘電体）５と隣接するＳｉＣ（誘電体）５の間に該ＳｉＣ（誘電体）５の表面抵抗より高い抵抗を有する高純度Ａｌ₂Ｏ₃ (絶縁体)６を介在させた静電チャックを得た。なお、二枚のＳｉＣ（誘電体）５の間に介在した高純度Ａｌ₂Ｏ₃ (絶縁体)６の幅は８ｍｍとした。
【００１４】
比較例１
ＳｉＣ（誘電体）５及び高純度Ａｌ₂Ｏ₃ (絶縁体)６は実施例１と同様の材料を使用し、このうちＳｉＣ（誘電体）５は、図７に示すように６６ｍｍ×４７ｍｍ×厚さ２ｍｍの寸法に加工し、ＳｉＣ（誘電体）５の片側全面に実施例１で用いた速乾性導電ペーストを塗布し、自然乾燥して厚さが２０μｍの電圧印加電極３を形成した。一方、高純度Ａｌ₂Ｏ₃ (絶縁体)は、実施例１と同一の寸法のものを用いた。
【００１５】
この後、図８に示すように、高純度Ａｌ₂Ｏ₃ (絶縁体)６の片側面に前記のＳｉＣ（誘電体）５を埋め込むための窪みを設け、さらに該窪みの底部から反対側の表面に貫通する電圧印加電極用孔７を形成し、しかる後前記窪みの部分にＳｉＣ（誘電体）５に形成した電圧印加電極３を下側に向けて挿入し、窪みと電圧印加電極３とを絶縁性エポキシ接着剤(チバガイギー社製、商標名アラルダイト)で接着し、次いでＳｉＣ（誘電体）５とＡｌ₂Ｏ₃(絶縁体)の両表面を同時に研磨して吸着面を面一とした、誘電体と隣接する誘電体との間に高純度Ａｌ₂Ｏ₃ (絶縁体)６を介在しない一枚のＳｉＣ（誘電体）５からなる静電チャックを得た。
【００１６】
次に、上記の実施例１及び比較例１で得た静電チャックにおいて、各々吸着時に流れる全漏れ電流を測定した。そのときの測定回路を図９に示す。
なお、被吸着物として、シリコンウェーハの裏面と、シリコンウェーハの裏面に厚さが０．３μｍのインジウム−スズ導体膜を施した液晶用ガラスの２種類の被吸着物を使用し、誘電体が全て覆われるように全面吸着し測定し、シリコンウェーハの裏面での測定結果を表1及びシリコンウェーハの裏面に厚さが０．３μｍのインジウム−スズ導体膜を施した液晶用ガラスでの測定結果を表２に示す。
【００１７】
【表１】

【００１８】
【表２】

【００１９】
表１及び表２に示されるように本発明になる実施例の静電チャックは、比較例の静電チャックに比較して漏れ電流が少なく、特に表２に示すシリコンウェーハの裏面に厚さが０．３μｍのインジウム−スズ導体膜を施した液晶用ガラスでの測定結果では、ガラスの体積固有抵抗が大きく誘電体の厚さ方向の電流も流れず、誘電体の表面電流を遮断していることが明らかである。
なお、実施例では単極型の誘電体を２枚使用したもので説明したが、２枚以上の多極型の静電チャックで、各電圧印加電極間の電位差を３段階以上に設定しても効果が変わらないことは明らかである。
【００２０】
【発明の効果】
本発明における静電チャックは、誘電体に形成される電極間の誘電体の表面電流を著しく低減し、半導体デバイス製造装置、液晶デバイス製造装置、特に電子線を使用した装置や液晶ガラスを搬送する装置に好適である
【図面の簡単な説明】
【図１】本発明の原理的構成を説明する静電チャックの断面図である。
【図２】図１の電気的等価回路を示す図である。
【図３】本発明の実施例になる静電チャックの要部を示す斜視図である。
【図４】図３のＡ−Ａ線断面図である。
【図５】従来の原理的構成を説明する静電チャックの断面図である。
【図６】図５の電気的等価回路を示す図である。
【図７】従来の静電チャックの要部を示す斜視図である。
【図８】図７のＢ−Ｂ線断面図である。
【図９】漏れ電流を測定するための測定回路を示す図である。
【符号の説明】
１誘電体
２絶縁体
３電圧印加電極
４被吸着物
５ＳｉＣ
６高純度Ａｌ₂Ｏ₃
７電圧印加用孔[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrostatic chuck used in a semiconductor / liquid crystal field such as a semiconductor device manufacturing apparatus and a liquid crystal device manufacturing apparatus, and more particularly to a bipolar electrostatic chuck.
[0002]
[Prior art]
When manufacturing semiconductor devices and liquid crystal devices, electrostatic chucks capable of surface adsorption have been studied from the conventional mechanical clamp system in order to hold a silicon wafer, a glass substrate, etc., particularly in a vacuum atmosphere.
The dielectric material constituting the electrostatic chuck has a specific resistance value determined by the thickness and the electrode area. When a voltage of several hundred volts or more is applied during adsorption, a leakage current corresponding to the specific resistance of the dielectric flows. .
[0003]
A bipolar electrostatic chuck having a pair of positive and negative electrodes has the advantage of simplifying the mechanism of the device because no ground connection is made to the object to be attracted. However, a conventional bipolar electrostatic chuck has one advantage. A pair of electrodes are formed on the dielectric, and in addition to the current due to the inherent resistance value determined by the thickness of the dielectric material and the electrode area, it is determined by the electrode spacing between the electrodes and the edge length between the counter electrodes A so-called surface current flows.
[0004]
Even if the surface current is several μA, it cannot be ignored in a device affected by a minute electromagnetic field such as a device using an electron beam. In an electrostatic chuck for liquid crystal glass that adsorbs an insulating substrate as shown in JP-A-11-163110 and the like through a conductor film on the back surface, the surface current becomes several mmA or more by applying a high voltage. Therefore, an expensive power source with a high current capacity is required, and reduction of the surface current is desired in the bipolar electrostatic chuck.
[0005]
[Problems to be solved by the invention]
The invention according to claim 1 provides an electrostatic chuck that significantly reduces the surface current of the dielectric between the electrodes formed on the dielectric.
[0006]
[Means for Solving the Problems]
The present invention has a base made of an insulator and a plurality of dielectrics, and a voltage application electrode is formed on each dielectric. Further , the surface resistance of the dielectric is between the dielectric and the adjacent dielectric. The present invention relates to an electrostatic chuck formed by interposing an insulator made of the same material as that of the substrate having high resistance. In addition, an insulator interposed between the dielectric and an adjacent dielectric and having a resistance higher than the surface resistance of the dielectric is integral with the insulator serving as a base. In addition, the dielectric is SiC, and the insulator is Al ₂ O ₃ .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
As the dielectric material used in the electrostatic chuck of the present invention, ceramic materials such as Al ₂ O ₃ , Si ₃ N ₄ , AlN, SiC, BaTiO ₃ are used.
The voltage application electrode formed on the dielectric is formed by baking a glass paste containing a metal such as Ag-Pd, W, Ag, or Au, or by adhering a metal plate or metal foil such as Al, Cu, or SUS. Can do.
[0008]
An insulating material used for an insulator having a resistance higher than the surface resistance of the dielectric that is interposed between the dielectric and the dielectric adjacent to the base is high in dielectric breakdown voltage, high in insulation resistance, purity Al ₂ O ₃ (purity 90%), SiO ₂ or the like is Ru is used. The insulating material used for the insulator having a higher resistance than the surface resistance of the dielectric between the dielectric and the adjacent dielectric is preferably a material having a volume specific resistance of 10 times or more higher than that of the dielectric. It is more preferable if it is 50 times or more, and there is no particular limitation on the upper limit.
[0009]
The dielectric material used for the insulating material having a higher resistance than the surface resistance of the dielectric between the dielectric and the adjacent dielectric are not permissible even an insulator integral with the base. If the adsorption surface travels from a dielectric surface with a monopolar structure, a gap is created between the dielectric and the adsorbate during adsorption, and the desired adsorption force cannot be obtained. It is preferable to do.
[0010]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a sectional view of an electrostatic chuck for explaining the principle configuration of the present invention, FIG. 2 is a diagram showing an electrical equivalent circuit thereof, and FIG. 3 is a perspective view showing a main part of the electrostatic chuck according to an embodiment of the present invention. 4 is a cross-sectional view taken along line AA of FIG. 3, FIG. 5 is a cross-sectional view of an electrostatic chuck for explaining a conventional principle configuration, FIG. 6 is a diagram showing an electrical equivalent circuit thereof, and FIG. FIG. 8 is a sectional view taken along line BB in FIG. 7 and FIG. 9 is a diagram showing a measurement circuit for measuring leakage current. 1 is a dielectric, 2 is insulation 3 is a voltage application electrode, 4 is an object to be adsorbed, 5 is SiC, and 6 is high-purity Al ₂ O ₃ .
[0011]
The electrostatic chuck of the present invention shown in FIG. 1 intervenes a large resistance Rz (Rz> Rs) of the insulator 2 due to the surface current caused by the surface resistance Rs of the dielectric 1 generated in the conventional electrostatic chuck shown in FIG. Can be reduced. Further, if the resistance value Rz of the insulator 2 is made much larger than the surface resistance Rs of the dielectric 1 (Rz >> Rs), the surface current caused by the surface resistance Rs of the dielectric 1 can be cut off.
[0012]
EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not restrict | limited to this.
Example 1
As shown in FIG. 3, SiC (Hitachi Chemical Industry Co., Ltd., trade name: Hexalloy) 5 having a volume resistivity of 1 × 10 ⁹ Ωm and dimensions of 66 mm × 24.5 mm × thickness 2 mm is used as the dielectric. One piece of high-purity Al ₂ O ₃ (trade name: Halox, manufactured by Hitachi Chemical Co., Ltd.) 6 having a volume resistivity of 1 × 10 ¹⁴ Ωm and dimensions of 100 mm × 100 mm × thickness 10 mm is used as the sheet and insulator. Then, a fast-drying conductive paste (trade name: Sylveste, manufactured by Tokuri Chemical Co., Ltd.) was applied to the entire surface of one side of SiC (dielectric) 5 and naturally dried to form a voltage application electrode 3 having a thickness of 20 μm.
[0013]
Thereafter, as shown in FIG. 4, a recess for embedding the SiC (dielectric) 5 is provided on one side surface of the high-purity Al ₂ O ₃ (insulator) 6, and further on the opposite side from the bottom of the recess. A voltage application electrode hole 7 penetrating the surface is formed, and then the voltage application electrode 3 formed on the SiC (dielectric) 5 is inserted downward into the depression, and the depression, the voltage application electrode 3, Are bonded with an insulating epoxy adhesive (trade name Araldite, manufactured by Ciba Geigy Co., Ltd.), and then both surfaces of SiC (dielectric) 5 and high-purity Al ₂ O ₃ (insulator) 6 are simultaneously polished to face the adsorption surface. A high-purity Al ₂ O ₃ (insulator) 6 having a resistance higher than the surface resistance of the SiC (dielectric) 5 is interposed between the SiC (dielectric) 5 and the adjacent SiC (dielectric) 5. An electrostatic chuck was obtained. The width of the high-purity Al ₂ O ₃ (insulator) 6 interposed between the two SiC (dielectrics) 5 was 8 mm.
[0014]
Comparative Example 1
SiC (dielectric) 5 and high-purity Al ₂ O ₃ (insulator) 6 use the same materials as in Example 1, and SiC (dielectric) 5 is 66 mm × 47 mm × as shown in FIG. The electrode was processed to a dimension of 2 mm in thickness, and the quick-drying conductive paste used in Example 1 was applied to the entire surface of one side of SiC (dielectric) 5 and dried naturally to form a voltage application electrode 3 having a thickness of 20 μm. On the other hand, high-purity Al ₂ O ₃ (insulator) having the same dimensions as in Example 1 was used.
[0015]
Thereafter, as shown in FIG. 8, a recess for embedding the SiC (dielectric) 5 is provided on one side surface of the high-purity Al ₂ O ₃ (insulator) 6, and further on the opposite side from the bottom of the recess. A voltage application electrode hole 7 penetrating the surface is formed, and then the voltage application electrode 3 formed on the SiC (dielectric) 5 is inserted downward into the depression, and the depression, the voltage application electrode 3, Are bonded with an insulating epoxy adhesive (trade name Araldite, manufactured by Ciba Geigy Co., Ltd.), and then both surfaces of SiC (dielectric) 5 and Al ₂ O ₃ (insulator) are polished at the same time so that the adsorption surface is flush. Then, an electrostatic chuck made of a single SiC (dielectric) 5 without high-purity Al ₂ O ₃ (insulator) 6 interposed between the dielectric and the adjacent dielectric was obtained.
[0016]
Next, in the electrostatic chucks obtained in Example 1 and Comparative Example 1 described above, the total leakage current flowing during the adsorption was measured. The measurement circuit at that time is shown in FIG.
In addition, as the adsorbent, two types of adsorbents were used: a back surface of a silicon wafer and a liquid crystal glass having a 0.3 μm thick indium-tin conductor film on the back surface of the silicon wafer. Adsorption is measured so that the entire surface is covered, and the measurement result on the back surface of the silicon wafer is measured with Table 1 and the glass for liquid crystal with a 0.3 μm thick indium-tin conductor film on the back surface of the silicon wafer. Is shown in Table 2.
[0017]
[Table 1]

[0018]
[Table 2]

[0019]
As shown in Tables 1 and 2, the electrostatic chucks of the examples according to the present invention have less leakage current than the electrostatic chucks of the comparative examples, and in particular, the thickness on the back surface of the silicon wafer shown in Table 2 According to the measurement results with glass for liquid crystal with a 0.3 μm indium-tin conductor film, the volume resistivity of the glass is large and no current flows in the thickness direction of the dielectric, blocking the surface current of the dielectric. It is clear.
In the embodiments, two monopolar dielectrics are used. However, with two or more multipolar electrostatic chucks, the potential difference between each voltage application electrode is set to three or more levels. It is clear that the effect does not change.
[0020]
【The invention's effect】
The electrostatic chuck according to the present invention significantly reduces the surface current of the dielectric between the electrodes formed on the dielectric, and transports semiconductor device manufacturing equipment, liquid crystal device manufacturing equipment, particularly equipment using electron beams and liquid crystal glass. Suitable for devices [Brief description of the drawings]
FIG. 1 is a cross-sectional view of an electrostatic chuck for explaining the basic configuration of the present invention.
FIG. 2 is a diagram showing an electrical equivalent circuit of FIG. 1;
FIG. 3 is a perspective view showing a main part of an electrostatic chuck according to an embodiment of the present invention.
4 is a cross-sectional view taken along line AA in FIG.
FIG. 5 is a cross-sectional view of an electrostatic chuck for explaining a conventional principle configuration.
6 is a diagram showing an electrical equivalent circuit of FIG. 5;
FIG. 7 is a perspective view showing a main part of a conventional electrostatic chuck.
8 is a cross-sectional view taken along line BB in FIG.
FIG. 9 is a diagram showing a measurement circuit for measuring leakage current.
[Explanation of symbols]
1 Dielectric 2 Insulator 3 Voltage Application Electrode 4 Adsorbed Object 5 SiC
6 High purity Al ₂ O ₃
7 Voltage application hole

Claims

Has a base and a plurality of dielectric made of an insulating material, and the voltage application electrode formed on each of the dielectric between the dielectric and further adjacent to the dielectric, higher than the surface resistance of the dielectric resistance An electrostatic chuck comprising an insulator made of the same material as that of the substrate .

2. The electrostatic structure according to claim 1, wherein an insulator interposed between the dielectric and an adjacent dielectric and having a resistance higher than a surface resistance of the dielectric is integrated with an insulator serving as a base. Chuck.

3. The dielectric according to claim 1, wherein the dielectric is SiC and the insulator is Al. _２2 O _３3 An electrostatic chuck characterized by being.