JP2001068539A - Electrostatic chuck - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent erosion f an organic adhesive, even in a highly corrosive gas by applying coatings of an inorganic coating material to exposed portions of the organic adhesive for adhering a dielectric substrate, having a suction surface to a support substrate. SOLUTION: A chuck 1 is constructed, such that an electrode 3 is formed on the underside of a dielectric substrate 2 by plating, screen-printing or the like. Then a support substrate 4 is provided under the electrode 3 for adhesion to the substrate 2 with an organic adhesive 5. Thereafter, portions of the adhesive 5 exposed to side surfaces are coated with an inorganic coating material 8. An electrode terminal 6 is brought into contact with the electrode 3 via a through-hole in the substrate 4. The substrate 2 is normally made of an insulating or conductive ceramic, while the substrate 4 is made of an insulating ceramic, a surface-insulated metal or the like. Since a direct current source 7 is connected to the electrode 3 of the chuck 1 via the terminal 6, when a direct current is fed to the electrode 3, the chuck 1 electrostatically chucks a silicon wafer that is mounted on a chucking surface 2a of the substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art As a jig for fixing and transporting a silicon wafer or the like in a semiconductor manufacturing apparatus or the like, an electrode is arranged below a dielectric layer substrate, and a DC voltage is applied to the electrode to attract the upper surface of the dielectric layer substrate. An electrostatic chuck that electrostatically attracts a silicon wafer to a surface is used.

In particular, in an etching apparatus, the wafer temperature is 2
Since the temperature is not higher than 00 ° C., an electrode is arranged between a thin dielectric layer substrate made of alumina, aluminum nitride, zirconia, sapphire, etc. and a supporting substrate made of insulating ceramics or the like supporting the substrate, and the dielectric layer substrate is supported. 2. Description of the Related Art An electrostatic chuck having a structure in which an electrode is fixed while a substrate is adhered with an organic adhesive is used.

An electrostatic chuck having such a structure is
There is an advantage that the fabrication is simple, the size can be increased, and the dielectric layer substrate and the supporting substrate can be bonded at low cost without any problem.

This electrostatic chuck uses a highly corrosive gas,
For example, fluorine-based gas (for example, SF ₆ , CF ₄ , NF
₃ ), chlorine-based gas (for example, BCI ₃ , Cl ₂ , SiCl ₄₎
Etc.) are often used in such gases. These gases may be mixed with O ₂ gas, Ar gas, or the like as needed.

[0006]

However, when this electrostatic chuck is used in a highly corrosive gas, the gap between the dielectric layer substrate and the support substrate before the dielectric layer substrate or the support substrate is eroded. There is a problem that the exposed portion of the existing organic adhesive is eroded, and as a result, the internal electrode is exposed and abnormal discharge occurs.

The present invention has been made in view of the above-mentioned problems of the electrostatic chuck, and has as its object to prevent the organic adhesive from corroding even when used in a highly corrosive gas. It is to provide a possible electrostatic chuck.

[0008]

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 exposed portion of the organic adhesive is covered with an inorganic coating material having excellent corrosion resistance, the organic adhesive can be obtained. The inventors have found that the erosion of the adhesive can be prevented, and have completed the present invention.

That is, according to the present invention, (1) an electrode is arranged below a dielectric layer substrate having an adsorption surface for adsorbing an object to be adsorbed, a support substrate is further arranged below the electrode, and the dielectric layer substrate is supported. An electrostatic chuck in which a substrate is adhered with an organic adhesive, wherein an exposed portion of the organic adhesive is coated with an inorganic coating material (claim 1). (2) The electrostatic chuck according to claim 1, wherein the inorganic coating material is made of a water-soluble binder such as lithium silicate, silica sol, and boehmite. ) Wherein said dielectric layer substrate comprises:
The gist of the present invention is to provide an electrostatic chuck according to claim 1 or 2, wherein the electrostatic chuck is larger than the support substrate. This will be described in more detail below.

As described above, as the electrostatic chuck for preventing the erosion of the organic adhesive, an electrostatic chuck in which an exposed portion of the organic adhesive is covered with an inorganic coating material. 1).

The organic adhesive for fixing the electrode does not erode the portion covered with the dielectric layer substrate and the supporting substrate, but erodes the uncovered exposed portion, so that the portion has excellent corrosion resistance. By coating with an inorganic coating material, it is possible to obtain an electrostatic chuck that can prevent erosion of an organic adhesive even when used in a highly corrosive gas.

As the inorganic coating material, a coating material made of a water-soluble binder such as lithium silicate, silica sol, boehmite or the like is used.

Any other inorganic material having excellent corrosion resistance may be used. In particular, since these coating materials are cured by evaporating the solvent at around room temperature, they are used for bonding the dielectric layer substrate and the supporting substrate. Even if an organic adhesive having low heat resistance is used, the adhesive at the exposed portion can be covered without being deteriorated by the heat of curing.

Further, by adding a required amount of ceramic powder such as alumina, zirconia, or silica as an inorganic filler to the inorganic coating material, the thermal expansion coefficient of the inorganic coating material can be easily adjusted to the dielectric layer substrate or the supporting substrate. And obstruction caused by a difference in thermal expansion and contraction caused by a change in temperature can be eliminated.

As the ceramic powder to be added,
For example, when using silicon carbide as the dielectric layer substrate, use a mixed powder of zirconia and silica having a close thermal expansion coefficient as a main component of the inorganic filler, and when using alumina or zirconia as the dielectric layer substrate, use as the inorganic filler. Alumina powder or zirconia powder may be used.

On the other hand, the size of the dielectric layer substrate with respect to the supporting substrate also has a great influence on the erosion by the corrosive gas, and the size of the dielectric layer substrate is a dielectric layer substrate larger than the supporting substrate.

If the dielectric layer substrate is larger than the supporting substrate, the portion where the dielectric layer substrate and the supporting substrate are bonded, where the adhesive is exposed, is located on the back surface of the dielectric layer substrate, so that the substrate is directly exposed to corrosive gas. Erosion of the organic adhesive coated on the inorganic coating material is further reduced.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. In the electrostatic chuck shown in FIG. 1, the electrodes 3 are formed on the lower surface of the dielectric layer substrate 2 by plating or screen printing.
Is formed, a support substrate 4 is disposed below the substrate, and the substrate is adhered with an organic adhesive 5, and then the exposed portion of the organic adhesive on the side surface is covered with an inorganic coating material 8. The electrode terminals 6 were brought into contact with the electrodes 3 through the through holes of the support substrate 4.

The dielectric layer substrate is usually made of insulating ceramics or conductive ceramics, and the supporting substrate is made of insulating ceramics or a metal whose surface is insulated. The organic adhesive is not particularly limited, but preferably has corrosion resistance. Therefore, it is preferable to use a silicon adhesive or the like.

The manufactured electrostatic chuck is connected to a DC power supply 8
Is connected to the electrode 3 through the electrode terminal 6, the DC power is turned on to supply power to the electrode 3, whereby the silicon wafer placed on the suction surface 2 a of the dielectric layer substrate 2 is electrostatically attracted. You.

The structure of the electrostatic chuck shown in FIG. 1 is not limited to this. As shown in FIG. 2, an electrode 3 is formed on an upper surface of a support substrate 4 and a dielectric layer substrate 2 is formed on top of the electrode 3. After bonding with the system adhesive 5, the exposed portion of the adhesive may be covered with an inorganic coating material 8, or as shown in FIG. After bonding the dielectric layer substrate 2 with an organic adhesive, the exposed portion of the adhesive may be covered with an inorganic coating material 8.

On the other hand, in the case where the dielectric layer substrate is an electrostatic chuck larger than the supporting substrate, as shown in FIG. 4, the supporting substrate 4 shown in FIG. Is located on the back surface of the dielectric layer substrate 2 so that the structure is not directly exposed to the corrosive gas existing above the dielectric layer substrate.

With the electric chuck as described above,
Even when used in a highly corrosive gas, an electrostatic chuck that can prevent erosion of the organic adhesive can be obtained.

[0024]

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

(Example) (1) Production of Electrostatic Chuck A ZrO ₂ substrate was used as a dielectric layer substrate, a monopolar electrode was formed by Cu plating on the lower surface of the dielectric layer substrate, and ZrO ₂ was formed under the electrode. After arranging the supporting substrate, the dielectric layer substrate and the supporting substrate were bonded with a silicon adhesive, and the electrodes were fixed at the same time.

Next, the electrode terminal is inserted through the through hole of the support substrate, and is brought into contact with the electrode. Then, alumina powder as an inorganic filler is applied to the exposed portion of the adhesive on the side surface between the dielectric layer substrate and the support substrate. After coating the inorganic coating material made of added silica sol and evaporating the solvent sufficiently, it is cured to produce a monopolar electrostatic chuck in which the exposed portion of the organic adhesive is completely covered with the inorganic coating material. did. Note that the size of the dielectric layer substrate and the size of the support substrate were each φ200 × 2 ^t mm.

(2) Evaluation A silicon wafer was placed on the suction surface of the obtained electrostatic chuck, and the silicon wafer was placed in a vacuum container having a degree of vacuum of 0.1 Toor, and a corrosive gas (CF ₄ + O) was placed in the container. ₂ = 50 + 10
After injecting SCCM), a DC voltage of 2 kV was applied to the electrodes of the electrostatic chuck to cause the wafer to be attracted and allowed to elapse for 10 hours. As a result, no abnormal discharge was observed even after 10 hours, and the silicon wafer could be stably fixed by suction.

(Comparative Example) As a comparative example, an electrostatic chuck in which the exposed portion of the adhesive was not covered with an inorganic coating material was produced, and the same was evaluated. As a result, when 6 hours had passed, abnormal discharge was observed from the side surface of the electrostatic chuck. When the exposed portion of the adhesive was visually observed, a portion of the adhesive was eroded, and a portion of the erosion extending to the electrode was observed. Since the peripheral portion has changed to black, it is considered that abnormal discharge has occurred from here.

[0029]

As described above, with the electrostatic chuck according to the present invention, an electrostatic chuck that can prevent the erosion of the organic adhesive even when used in a highly corrosive gas can be obtained. Now you can.

[Brief description of the drawings]

FIG. 1 is a diagram in which electrodes are formed on a dielectric layer substrate, and an organic adhesive is coated with an inorganic coating material.

FIG. 2 is a diagram in which an electrode is formed on a support substrate and an organic adhesive is coated with an inorganic coating material.

FIG. 3 is a diagram in which an organic adhesive is coated with an inorganic coating material, while the supporting substrate also serves as an electrode.

FIG. 4 is a diagram in which an organic adhesive is coated with an inorganic coating material when the dielectric layer substrate is larger than the supporting substrate.

[Description of Signs] 1: Electrostatic chuck 2: Dielectric layer substrate 2a: Adsorption surface 3: Electrode 4: Support substrate 5: Organic adhesive 6: Electrode terminal 7: DC power supply 8: Inorganic adhesive

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoichi Shirakawa 1-2-23 Kiyosumi, Koto-ku, Tokyo Pacific Cement Co., Ltd. Kiyosumi Research Laboratory, Research Headquarters F-term (reference) 3C016 AA01 BA01 CE05 GA10 5F031 CA02 HA16 MA32

Claims (3)

[Claims] An electrode is arranged below a dielectric layer substrate having an adsorption surface for adsorbing an object to be adsorbed, a support substrate is further arranged below the electrode, and the dielectric layer substrate and the support substrate are organically bonded. An electrostatic chuck, wherein an exposed portion of the organic adhesive is covered with an inorganic coating material in the electrostatic chuck bonded with an agent. 2. The method according to claim 1, wherein the inorganic coating material is lithium silicate,
2. The electrostatic chuck according to claim 1, comprising a water-soluble binder such as silica sol or boehmite. 3. The electrostatic chuck according to claim 1, wherein the dielectric layer substrate is larger than the support substrate.