JP2002093896A - Electrostatic chuck and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost electrostatic chuck, together with its manufacturing method, which is satisfactory in heat-resistance and corrosion-resistance. SOLUTION: An electrostatic chuck is provided, which comprises a ceramic dielectrics layer 1, a ceramic insulating body substrate layer 2, an internal electrode layer 3 for electrostatic attraction, and an external-connection lead electrode 4 for applying voltage to the internal electrode layer 3. The lead electrode includes a conductive metal silicide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck for electrostatically holding and adsorbing a wafer or the like in a semiconductor manufacturing apparatus or the like, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, semiconductor manufacturing equipment
When performing exposure processing, film formation processing, or etching processing on a wafer or the like, it is necessary to hold the wafer while maintaining its flatness, or to hold the wafer with good adhesion to obtain uniform heat. As for, a mechanical holding system, a vacuum suction system, and an electrostatic suction system have been proposed.

[0003] Among them, the electrostatic attraction method is a method of holding a wafer or the like by generating an electrostatic attraction force by applying a voltage to an electrode layer via a dielectric layer.
It has been widely used because it has excellent flatness of the wafer processing surface, good adhesion to the adsorption surface, and can be used in vacuum (for example, `` Electronic Materials '' July 1996, p.51) .

As the dielectric, an organic film such as polyimide, sprayed ceramics, sintered ceramics, and the like are used. Among these, the sintered ceramics have durability, heat resistance, withstand voltage, and flatness. The degree of necessity is increasing with the increase in the diameter of the wafer and the miniaturization of the process.

[0005] There are two main methods for manufacturing a sintered ceramic electrostatic chuck.

One is a method in which dielectric ceramics and ceramics serving as an insulating substrate are individually baked and then joined so as to sandwich the internal electrodes. The joining includes a method using an adhesive (for example, Japanese Utility Model No. 2552420) and a method for brazing (for example, Japanese Patent No. 2836986).
If cooling or the like is required during use, this electrostatic chuck is further joined to an aluminum alloy disk or the like having a cooling function. Then, at the same time as the joining of the dielectric and the insulating substrate, or after the joining of both, the lead electrode is attached through a hole penetrating the insulating substrate. For mounting, a method using a conductive adhesive or a method of brazing (for example,
JP-A-2000-12133).

Another method is to sandwich an internal electrode between a dielectric ceramic substrate and a ceramic substrate serving as an insulating substrate in advance and fire them at the same time. In this case, the firing method includes a method in which a dielectric body formed by doctor blade molding and an insulating substrate body are pressure-bonded with a roll or the like in advance with an internal electrode therebetween, and then fired under normal pressure (for example, Japanese Patent Application No. 62-264).
No. 638) and a method in which a dielectric substrate and an insulating substrate substrate are overlapped with an internal electrode interposed therebetween, followed by hot press firing (for example, Japanese Patent Application No. 6-59077). Even in these cases, the lead electrode is attached or brazed through a hole previously penetrated through the insulator substrate or a hole formed after firing. Also, in this case, if cooling or the like is required during use, this electrostatic chuck is further joined to an aluminum alloy disk or the like having a cooling function.

[0008]

When mounting the lead electrodes by post-processing such as an adhesive or brazing after firing the ceramic dielectric, there are some disadvantages.

For one thing, heat resistance is impaired. In a CVD apparatus, a sputtering apparatus, or the like, the electrostatic chuck is used at a high temperature. As a brazing material for brazing the lead electrode, a low melting point alloy or the like is used, but of course, it cannot be used at a temperature higher than its melting point. In the case of a conductive adhesive, the heat resistance is even lower, and it can usually be used only at about 200 ° C. or less. An electrostatic chuck or the like in which a dielectric and an insulator substrate are simultaneously baked has higher heat resistance than an electrostatic chuck manufactured by bonding them, but even in this case, the heat resistance of the lead electrode is limited.

There is also a problem in corrosion resistance. In some cases, an electrostatic chuck is used in a corrosive atmosphere such as an etching apparatus. In this case, corrosion may occur in the mounting portion of the lead electrode, which may shorten the life of the electrostatic chuck.

[0011] Further, by joining the lead electrodes with an adhesive or brazing, residual stress is generated due to shrinkage or thermal stress during bonding, and the flatness of the surface where the lead electrodes are formed on the back side is degraded. May be.

Further, in any case, in order to produce the lead electrode in a post-process after firing, a process such as perforation and bonding is required, which increases the manufacturing cost.

In view of the above, the present invention replaces the above-described conventional electrostatic chuck in which a metal lead electrode made of stainless steel or titanium is joined with a conductive adhesive, low-temperature solder, brazing material, or the like. An object of the present invention is to provide an inexpensive electrostatic chuck having excellent heat resistance and corrosion resistance and a method for manufacturing the same.

[0014]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, have obtained a dielectric layer, an insulating substrate layer, an internal electrode layer, and a lead electrode of an electrostatic chuck. It has been found that heat resistance and corrosion resistance can be improved by firing together.

What is important here is that in firing ceramics, the ceramic substrate undergoes firing shrinkage. Further, since the sintering is usually performed at a high temperature of 1000 ° C. or more, large thermal expansion / contraction occurs. Therefore, when different materials such as electrodes are fired simultaneously, this point must be taken into consideration.

The firing shrinkage in the hot press occurs in the pressing direction. Therefore, firing shrinkage does not occur much in a plane perpendicular to the pressing direction. Even if internal electrodes with different sintering behavior are formed in advance by screen printing or fired with metal members in between, there is no significant shrinkage in the in-plane direction, and there is also an effect by pressure, and the shape is also a film. Because of the shape
Relatively easy firing is relatively easy.

On the other hand, since the lead electrode is a member formed in the pressing direction and has a pin shape,
If the sintering behavior is different, cracks will occur during firing.

The present inventors have proposed that a metal silicide, while having conductivity, be applied to ceramics used as a dielectric for an electrostatic chuck, such as alumina and aluminum nitride, by sintering such as sintering temperature and coefficient of thermal expansion. The present invention was completed by focusing on the fact that physical properties affecting the sintering behavior are close. For comparison, the physical properties of the materials used for the lead electrodes are shown in Table 1 together.

[0019]

[Table 1]

That is, the present invention is as follows. (1) An electrostatic chuck comprising a ceramic dielectric layer, a ceramic insulator substrate layer, an internal electrode layer for electrostatic attraction, and a lead electrode for external connection for applying a voltage to the internal electrode layer. An electrostatic chuck, wherein the lead electrode comprises a conductive metal silicide. (2) When the conductive metal silicide is TaSi ₂ , NbSi ₂ , WSi ₂ ,
The electrostatic chuck according to the above (1), wherein the electrostatic chuck comprises one or more kinds selected from MoSi ₂ . (3) The electrostatic chuck according to (1) or (2), wherein the ceramic dielectric layer is an alumina ceramic. (4) The electrostatic chuck according to (1) or (2), wherein the ceramic dielectric layer is an aluminum nitride ceramic. (5) The electrostatic chuck according to any one of (1) to (4), wherein the main composition of the ceramic dielectric layer and the ceramic insulator substrate layer is the same ceramic compound. (6) A method for manufacturing an electrostatic chuck including a ceramic dielectric layer, a ceramic insulator substrate layer, an internal electrode layer for electrostatic attraction, and a lead electrode for external connection for applying a voltage to the internal electrode layer. A molded body of a dielectric material
(A), a molded body (B) of an insulator substrate raw material, and a molded body (C) containing a conductive metal silicide of a lead electrode raw material are produced, and the molded body (A) or the molded body (B) is produced. A processing hole is formed in at least one of the holes, the formed body (C) is embedded in the processed hole, and the formed body (A) and the formed body (B) are overlapped with the internal electrode layer interposed therebetween. And then integrally firing by hot pressing. (7) The conductive metal silicide is TaSi ₂ , NbSi ₂ , WSi ₂ ,
The method for producing an electrostatic chuck according to the above (6), wherein the method comprises one or more selected from MoSi ₂ . (8) The method of manufacturing an electrostatic chuck according to (6) or (7), wherein the ceramic dielectric layer is made of alumina ceramic. (9) The method for manufacturing an electrostatic chuck according to (6) or (7), wherein the ceramic dielectric layer is an aluminum nitride ceramic. (10) The method for manufacturing an electrostatic chuck according to any one of (6) to (9), wherein a main composition of the ceramic dielectric layer and the ceramic insulator substrate layer is the same ceramic compound. .

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The electrostatic chuck of the present invention does not use a conductive adhesive or brazing material, so that even at a high temperature of 1000 ° C. or more, there is no problem at the joints and the heat resistance is extremely high.

Further, since the lead electrode, the insulator substrate, and the internal electrode are directly sintered, they have high corrosion resistance even in a corrosive atmosphere.

Furthermore, when the dielectric is fired, an insulating substrate,
By combining the internal electrodes and the lead electrodes and firing them at the same time, the manufacturing cost can be reduced.

The same material as the lead electrode,
W, Mo or other high melting point metal can be used, for example, paste of powder of these materials, dielectric substrate, and / or, screen printing on insulator substrate substrate, to provide internal electrodes Can be. Further, the internal electrodes may be provided so as to sandwich a plate-like or net-like high melting point metal member such as W or Mo.

It is preferable that the dielectric ceramic has a main composition of alumina or aluminum nitride because it has a sintering characteristic close to that of metal silicide. TiO ₂ or Ti ₂ O ₃ may be added to alumina for the purpose of adjusting electric resistivity.

As the conductive metal silicide, for example, TaSi
₂ , WSi ₂ , NbSi ₂ , MoSi ₂ , TiSi ₂ , ZrSi ₂ , CrSi _{2 and the} like. These may be used alone or in combination of two or more. Also, among these conductive metal silicides, Ta
Si ₂ , NbSi ₂ , WSi ₂ , and MoSi ₂ are particularly preferable because they have excellent conductivity and oxidation resistance and have a sintering behavior closer to that of dielectric ceramics.

Further, when the main composition of the dielectric and the insulating substrate is the same ceramic compound, the sintering behavior of the members occupying most of the volume of the electrostatic chuck becomes the same, which is more preferable.

Before firing the dielectric and insulator substrates,
The powder is formed in advance. This is because when the powder is filled into a hot press and baked, the filling becomes uneven because the internal electrode is likely to be cut during firing and the internal electrode after firing is warped. This is because the electrostatic adsorption characteristics become non-uniform. The molding may be performed by a method such as cold isostatic press molding or doctor blade molding.

The conditions for firing by hot pressing are not particularly limited as long as the dielectric ceramics, insulating ceramics, and lead electrodes, which are the materials, can be fired individually. For example, when alumina ceramics are used, firing can be performed in an argon atmosphere at a pressure of 10 to 50 MPa, a firing temperature of 1300 to 1700 ° C., and a firing time of 30 to 600 minutes. When aluminum nitride ceramics is used, the pressure is 10 to 50 MPa and the firing temperature is 170 in a nitrogen atmosphere.
The sintering can be performed at 0 to 2000 ° C. for a sintering time of 30 to 600 minutes.

As the work, the following modes are exemplified as preferred methods. A molded body (A) of a dielectric material, a molded body (B) of an insulating substrate material, and a molded body (C) containing a conductive metal silicide of a lead electrode material are produced. A processing hole is formed in at least one of the molded body (A) and the molded body (B). The molded body (C) is embedded in the processing hole, and the molded body
After the inner electrode layer is sandwiched between (A) and the molded body (B), they are baked together by hot pressing.

[0031]

The present invention will be described below in detail with reference to examples.

(Example 1) Distilled water, a binder, and a dispersant were added to α-Al ₂ O ₃ powder and mixed with a ball mill. The slurry was granulated with a spray drier to obtain granulated powder having a particle size of about 70 μm. Two discs were cold isostatically pressed into disks. One of these was machined from a substrate and the diameter was 315m.
m and a thickness of 10 mm were used as a dielectric substrate. The other was cut to a diameter of 315 mm and a thickness of 10 mm, and a hole having a diameter of 10 mm was drilled at the lead electrode take-out portion to obtain an insulating substrate substrate.
After screen printing TaSi ₂ paste on the dielectric substrate,
The insulator substrate was superimposed. After degreasing in air at 500 ° C. The TaSi ₂ powder is formed into a pellet having a diameter of 10 mm and a thickness of 10 mm, inserted into the hole of the lead electrode take-out part of the degreased insulator substrate, set in a hot press, and set at 1500 ° C. and 30 MPa in argon gas. It baked under pressure for 2 hours. The dielectric portion of the obtained sintered body was ground so as to have a thickness of 2 mm, and the whole was further processed into a disk shape having a diameter of 300 mm and a thickness of 5 mm to obtain an electrostatic chuck.

When the chucking force of this electrostatic chuck was measured at 500 ° C., it showed a chucking force of 4000 g / cm ² . Also, no defect such as peeling occurred at any of the portions.

Example 2 0.5% by weight of Ti ₂ was added to α-Al ₂ O ₃ powder.
O ₃ powder was added, distilled water, an acrylic binder, and a dispersant were added, followed by ball mill mixing to obtain a slurry having a viscosity of about 15,000 cP. After drying this with a doctor blade,
A sheet molded body having a thickness of about 300 μm was obtained. Several of these were laminated and cut into a disk having a diameter of 315 mm to obtain a dielectric substrate.

Α-Al ₂ O ₃ powder, distilled water, binder,
The dispersant was added and mixed with a ball mill. The slurry was granulated with a spray drier to obtain granulated powder having a particle size of about 70 μm. This was subjected to cold isostatic pressing into a disk shape, and then ground to a diameter of 315 mm and a thickness of 10 mm. A hole with a diameter of 10 mm was formed in a lead electrode take-out portion to obtain an insulator substrate substrate.

A W net was sandwiched between the dielectric substrate and the insulating substrate substrate, pressed with a roller, and degreased at 500 ° C. in the air. NbSi ₂ powder is formed into a pellet having a diameter of 10 mm and a thickness of 10 mm, inserted into the hole of the lead electrode take-out part of the degreased insulator substrate, set in a hot press, and set at 1500 ° C and 30 MPa in argon gas. It baked under pressure for 2 hours.
The dielectric portion of the obtained sintered body was ground to a thickness of 300 μm, and the whole was further processed into a disk shape having a diameter of 300 mm and a thickness of 5 mm to obtain an electrostatic chuck.

The obtained electrostatic chuck is corrosive at room temperature.
When used in an atmosphere of CF ₄ , it exhibited an adsorption force of 5000 g / cm ² . In addition, no corrosion was observed at any point even after 10 hours in the above atmosphere.

Example 3 1.0% by weight of Y ₂ O ₃ as a sintering aid
Ethanol, a binder, and a dispersant were added to the AlN powder, and the mixture was mixed in a ball mill. The slurry was granulated with a spray drier to obtain granulated powder having a particle size of about 50 μm. In the same manner as in Example 1, two discs were cold isostatically pressed to form a dielectric and an insulating substrate, respectively. A hole having a diameter of 10 mm was formed in the insulator substrate to serve as a lead electrode extraction portion. After screen-printing the W paste on the dielectric molded body, the base of the insulating substrate was overlapped. 800 ℃,
Defatted in nitrogen. WSi ₂ powder is formed into a pellet having a diameter of 10 mm and a thickness of 10 mm, inserted into the hole of the lead electrode take-out part of the degreased insulator substrate, set in a hot press, and placed in nitrogen at 1850 ° C. and 30 MPa at 2 MPa. It baked under pressure for a time. The dielectric portion of the obtained sintered body was ground to a thickness of 2 mm, and the whole was further processed into a disk shape having a diameter of 300 mm and a thickness of 5 mm to produce an electrostatic chuck.

When this electrostatic chuck was used in a corrosive CF ₄ atmosphere at 300 ° C., it showed an adsorption force of 4700 g / cm ² . Even after 10 hours in the above atmosphere, no peeling and corrosion were observed.

[0040]

According to the present invention, excellent heat resistance and corrosion resistance are obtained.
An electrostatic chuck with excellent durability can be obtained even in a high-temperature atmosphere or a corrosive atmosphere. Further, according to the manufacturing method of the present invention, an electrostatic chuck can be manufactured at a lower cost as compared with a process of separately manufacturing a power supply unit.

[Brief description of the drawings]

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

FIG. 2 is a perspective view of the electrostatic chuck of the present invention as viewed from above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ceramic dielectric 2 ... Ceramic insulating substrate 3 ... Internal electrode layer 4 ... Lead electrode

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3C016 GA10 4G001 BA03 BA09 BA13 BA36 BA48 BA49 BB03 BB09 BB13 BB36 BB48 BB49 BC42 BC52 BC54 BD38 5F031 CA02 HA02 HA03 HA16 PA11 PA30

Claims (10)

[Claims] An electrostatic chuck comprising a ceramic dielectric layer, a ceramic insulator substrate layer, an internal electrode layer for electrostatic attraction, and a lead electrode for external connection for applying a voltage to the internal electrode layer. Wherein the lead electrode comprises a conductive metal silicide. 2. The conductive metal silicide is TaSi ₂ , NbS
_2. The electrostatic chuck according to claim 1, comprising one or more selected from i ₂ , WSi ₂ , and MoSi ₂ . 3. The electrostatic chuck according to claim 1, wherein the ceramic dielectric layer is made of alumina ceramic. 4. The ceramic dielectric layer is made of aluminum nitride ceramics.
3. The electrostatic chuck according to 1 or 2. 5. The electrostatic chuck according to claim 1, wherein a main composition of the ceramic dielectric layer and the ceramic insulator substrate layer is the same ceramic compound. 6. An electrostatic chuck comprising a ceramic dielectric layer, a ceramic insulator substrate layer, an internal electrode layer for electrostatic attraction, and a lead electrode for external connection for applying a voltage to the internal electrode layer. In the manufacturing method, a molded body of a dielectric material (A), a molded body of an insulating substrate raw material (B), a molded body containing a conductive metal silicide of a lead electrode raw material (C) are produced,
Forming a processing hole in at least one of the molded body (A) or the molded body (B), embedding the molded body (C) in the processed hole,
A method for manufacturing an electrostatic chuck, comprising: stacking the internal electrode layer between the formed body (A) and the formed body (B), and firing them together by hot pressing. 7. The conductive metal silicide is TaSi ₂ , NbS
7. The method for producing an electrostatic chuck according to claim 6, comprising one or more selected from i ₂ , WSi ₂ , and MoSi ₂ . 8. The method according to claim 6, wherein the ceramic dielectric layer is made of alumina ceramic. 9. The ceramic dielectric layer is made of aluminum nitride ceramics.
Or the method of manufacturing an electrostatic chuck according to 7. 10. The method for manufacturing an electrostatic chuck according to claim 6, wherein a main composition of the ceramic dielectric layer and the ceramic insulator substrate layer are the same ceramic compound.