JPH1012712A - Electrostatic chuck device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic chuck device which has a large L electrostatic generation quantity and enables significant elongation of life of an electrostatic chuck and mass production of high-performance products. SOLUTION: An electrostatic chuck device includes a metal substrate 1 having a slit-like through hole 11 provided in the direction of thickness thereof and having a recessed portion 12 formed in a part on the back side adjacent to the through hole, and an electrostatic chuck sheet 2 adhered to the metal substrate via an adhesive layer. In the electrostatic chuck sheet, a slit-like cut-in portion having one end connected is formed along the shape of the through-hole. The cut-in portion passes through the through hole 11 of the metal substrate and is adhered to the recessed portion on the back side with an adhesive. A part of an electrode layer of the cut-in portion adhered to the recessed portion is exposed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrostatic chuck device to which an electrostatic chuck sheet capable of holding a conductive substance such as a semiconductor wafer in a vacuum is attached.

[0002]

2. Description of the Related Art In recent years, a semiconductor manufacturing process has rapidly become dry. In an etching apparatus, a plasma CVD apparatus, an ion implantation apparatus, an ashing apparatus, an electron beam lithography, an X-ray lithography, etc., a sample such as a semiconductor wafer is 1500 Pa or less. It is often performed in a vacuum.

Conventionally, a mechanical chuck or a vacuum chuck by a mechanical method has been often used for holding such a sample. However, for example, it is necessary to make the temperature distribution on the sample surface uniform. In recent years, there have been various problems such as the inability to use, the inability to use in a vacuum chamber, and the increase in the temperature of the sample.
An electrostatic chuck device using an electrostatic chuck sheet has been used. The electrostatic chuck device is very advantageous because it can hold the sample and the holder thermally uniform in a vacuum and with high reliability. Such an electrostatic chuck device is disclosed, for example, in British Patent No. 1443.
No. 215, comprising a substantially flat conductive support member coated with a layer of dielectric material as a main part, and having means for electrically contacting the wafer to be adsorbed; Thereby, a potential difference can be applied between the wafer and the support member. Such a potential difference creates an electrostatic attraction between the dielectric layers, thereby supporting the wafer substantially flat with respect to the conductive layers. Then, the wafer is adsorbed inside the vacuum chamber as described above, and the surface farther than the supporting member is irradiated with high-speed ions to perform processing.

In these electrostatic chuck devices, inorganic materials such as organic polymer materials and ceramics are used as dielectrics, and Cu, Ni, Sn and the like are used as internal electrodes for generating polarization charges. Other metal materials are used. As a method of supplying power to the internal electrodes, particularly in an electrostatic chuck using an organic polymer material, conventionally, an electrode inside a supply surface and a lead wire portion for supplying power to the electrode are integrally formed, and a lead wire is formed. The portion has a structure that is bent at an end of a part of the suction surface and taken out to the outside.

However, in the electrostatic chuck apparatus having this structure, when performing a plasma etching process by adsorbing a wafer on the surface of an electrostatic chuck sheet, it is necessary to protect the lead wire portion with a protective member and perform the process. However, at this time, a part of the lead wire portion is exposed between the wafer and the protection member, though very slightly. Therefore, when a process such as plasma etching is repeated, the exposed portion of the lead wire portion is exposed to plasma, and the exposed portion of the insulating layer is etched and thinned.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present inventors provide an electrostatic chuck sheet having a suction surface and supply electricity thereto as an electric joining method of an electrostatic chuck device. And a lead wire part for the electrostatic chuck sheet with a concave portion provided on the metal base so that high-speed ions do not hit them, a conductive adhesive, a low melting point solder, Alternatively, there has been proposed a technique for electrically connecting a metal spring and a conductive adhesive or the like (Japanese Patent Laid-Open No. 5-102289).

FIG. 5 shows an example of such a case, and is an enlarged cross-sectional view of an example of an electric connection portion between the electrostatic chuck sheet and the power supply sheet. Concave portions 12 and 13 having slit-like through holes 11 at appropriate positions on metal base 1
Is provided. The electrostatic chuck sheet 2 has a structure in which an insulating layer 21, an adhesive layer 22, an electrode layer 23, an adhesive layer 24, and an insulating layer 25 are sequentially laminated, and a concave portion of the metal base on a surface to be bonded to the metal base. Are provided with half-holes so that the electrode layer 23 is exposed. The belt-shaped power supply sheet 4 includes an insulating layer 41, an adhesive layer 42,
It has a structure in which the conductive layer 43, the adhesive layer 44, and the insulating layer 45 are sequentially laminated, and has a half-hole in the vicinity of both ends so that the conductive layer 43 is exposed.

The sheet for electrostatic chuck 2 has an adhesive layer 31
And the power supply sheet 4 is bonded to one side of the concave portion provided on the metal substrate and one side of the slit-like hole thereof via an adhesive layer 32. . The space formed between the semi-perforated hole formed in the adhesive layer 24 and the insulating layer 25 of the electrostatic chuck sheet and the semi-perforated hole formed in the insulating layer 41 and the adhesive layer 42 of the power supply sheet includes: The conductive adhesive 5 is filled, and the sheet electrode layer for the electrostatic chuck and the conductive layer of the power supply sheet are electrically joined.

However, this electrostatic chuck device is
Since the sheet for the electrostatic chuck and the lead wire portion are joined using a conductive adhesive, a low melting point solder, a metal spring, or the like, electrical connection may be insufficient, and the conductivity of the electrode layer may be reduced. And the amount of static electricity generated on the electrostatic chuck sheet is reduced, and the attraction force of the semiconductor wafer is low. Further, since it is necessary to bond the lead wire portion to the back surface of the electrostatic chuck sheet in the concave portion of the metal base, there is a problem that the manufacturing process of the electrostatic chuck device is complicated.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the electrostatic chuck device, and it is an object of the present invention to improve a power supply means to an electrode layer inside an electrostatic chuck sheet. Another object of the present invention is to provide an economical and highly reliable electrostatic chuck device which has a high static electricity generation amount, significantly prolongs the life of the electrostatic chuck, and is capable of mass-producing high-performance products.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies with the aim of improving the electric joining means in the above-mentioned conventional electrostatic chuck device, and as a result, have found that one of the suction surfaces of the sheet for the electrostatic chuck has been improved. It has been found that the above problem can be solved by using the portion as a lead wire portion, and the present invention has been completed.

That is, the electrostatic chuck device of the present invention comprises:
A metal substrate having a slit-shaped through hole in the thickness direction and a concave portion formed in a portion of the back surface adjacent to the through hole, and a sheet for an electrostatic chuck bonded to the metal substrate via an adhesive layer In the electrostatic chuck sheet, a slit-shaped cut portion having one end connected to the shape of the through hole is formed, and the cut portion penetrates the through hole of the metal base and a concave portion on the back surface. And a part of the electrode layer at the cut portion adhered to the concave portion is exposed.

FIG. 1 is a schematic sectional view of an electrostatic chuck device to which the electric bonding method of the present invention is applied, FIG. 2 is a plan view of an electrostatic chuck sheet used in the present invention, and FIG.
FIG. 2 is an enlarged sectional view of a main part in FIG. In the figure, 1
Is a metal base, a slit-shaped through hole 11 is provided at an appropriate position, and a concave portion 1 is formed in a portion of the back surface adjacent to the through hole.
2 are formed. Reference numeral 2 denotes a sheet for electrostatic chuck, which includes a first insulating layer 21, a first adhesive layer 22, and an electrode layer 2.
3, a second adhesive layer 24, and a second insulating layer 25 are sequentially laminated, and a slit-shaped one end is connected along the shape of the slit-shaped through hole of the metal base. A cut portion 2a is formed. An exposed portion 2 of the electrode layer is provided near the end of the slit-shaped cut portion.
3a are formed. The electrostatic chuck sheet 2 is bonded to the metal substrate 1 by an adhesive layer 3, and the slit-shaped cut portion 2 a passes through the through hole 11 and is bonded to the concave portion 12 on the back surface by the adhesive. Thereby, the exposed portion 23a of the electrode layer near the end of the slit-shaped cut portion is exposed in the concave portion.
Reference numeral 6 denotes a wafer in a mounted state.

Next, the material constituting the electrostatic chuck sheet used in the present invention will be described. The first and second insulating layers of the electrostatic chuck sheet are made of a material having excellent reliability such as heat resistance and voltage resistance. The thickness of the insulating layer greatly affects the electrostatic attraction force. Therefore, by making the thickness as thin as possible within a range that can sufficiently withstand the voltage applied between the electrodes, the electrostatic attraction force and the thermal conductivity are improved so that the withstand voltage characteristics are improved. It is necessary to use a high heat resistant plastic film. From such a point, in the present invention, 25 to 75 μm
It is preferable to use a thin polyimide film having a thickness of m or a plastic film having heat resistance of 150 ° C. or more.

Examples of the polyimide film include Kapton (Kapton: manufactured by DuPont), Apical (manufactured by Kanebuchi Chemical Industries), Upilex (manufactured by Ube Industries),
Nitmid (manufactured by Nitto Denki Kogyo), Superior Film (polyetherimide resin manufactured by Mitsubishi Plastics, Inc.) and the like. Examples of the plastic film having heat resistance of 150 ° C. or higher include, for example, fluororesin (fluoroethylene-propylene copolymer or the like), polyethersulfone, polyetheretherketone, stretched polyethylene terephthalate, stretched nylon, cellulose triacetate, And silicone rubber.

Also, if necessary, alumina, zirconium boride, boron nitride, etc., having a high thermal conductivity of 5 μm
It is effective to use a filler in which the following fillers are dispersed at a solid content ratio of 20 to 70%, but it is effective to use such a filler because the withstand voltage characteristic tends to decrease in spite of the effect of thermal conductivity. Consideration should be given to the points.

As the first and second adhesive layers of the electrostatic chuck sheet, an adhesive excellent in adhesive strength and heat resistance to both the insulating layer and the electrode layer is required, and a thermosetting or two-component curable adhesive is required. An adhesive is used. For example, polyester-based, polyurethane-based, polyimide-based, epoxy-based, modified polyamide-based, and rubber-based adhesives are effective, and these adhesives can be used alone or as a mixture.

In the present invention, these first and second
Has a particle size of 5 μm which can enhance the thermal conductivity of alumina, zirconium boride, boron nitride, silica, etc.
It is more effective to use a filler of m or less dispersed in a solid content ratio of 5 to 80%.

The coating film of the adhesive is capable of maintaining the adhesive strength.
A thickness of 30 μm is appropriate, and a thickness of 5 to 10 μm is most preferable from the viewpoint of manufacturing and workability. Since the first and second adhesive layers have the withstand voltage secured by the first and second insulating layers, the thickness may be reduced as long as the adhesive strength is not insufficient.

As the electrode layer, a copper foil having a thickness of 50 μm or less is usually used, but other than Ni, Cr, Fe, Al,
It may be a metal foil such as stainless steel or Sn, and in some cases, may be metal-deposited or plated,
Those coated with a conductive paint can also be used. 2 for copper foil
Those having a thickness of about 0 μm are most excellent in workability.

Further, in order to prevent discharge from occurring, the electrode layer needs to be sealed by the first and second adhesive layers so that the edge is not exposed to the outside. is there. As a method therefor, an electrode layer may be formed in a predetermined portion in advance by vapor deposition, etching, coating, or the like. In this case, it is necessary to prevent the electrode layer from existing in the cut portion so that the electrode layer is not exposed from the cut portion of the cut portion.

The sheet for an electrostatic chuck according to the present invention comprises:
An insulating adhesive is applied adjacent to the heat-resistant film serving as the first insulating layer to form a first adhesive layer, and an electrode layer having a predetermined shape is formed thereon to obtain a laminated sheet. While the second
A second adhesive layer is formed by applying an insulating adhesive on the heat-resistant film to be the insulating layer of the above, and after laminating and laminating this on the side of the laminated sheet on which the electrode layer is formed, heating is performed. Allow the adhesive to cure. Thereafter, a half-blanking process is performed on a preset portion to form a portion where the electrode layer is exposed,
Next, a predetermined portion is cut to form a cut portion, and a sheet for an electrostatic chuck used in the present invention is manufactured. In addition, the shape of the cut portion is not particularly limited, and the tip portion may have an arc shape, or may have a shape in which the tip portion is enlarged in a spoon shape.

As the adhesive which can be used to attach the electrostatic chuck sheet having the above-mentioned layer structure to the metal substrate, the same adhesive as used in the first and second adhesive layers can be used. In addition, it is preferable to add a filler to the adhesive for the purpose of enhancing thermal conductivity. The thickness of the adhesive layer formed between the electrostatic chuck sheet and the metal substrate is preferably in the range of 3 to 30 μm.

In the present invention, the electrostatic chuck sheet to be stuck on the metal substrate has an overall film thickness of 30 to 4 mm.
It is necessary to be within the range of 00 μm, and 80 to 15
A range of 0 μm is preferred. When the thickness is less than 30 μm, a problem occurs in workability. When the thickness is more than 400 μm, thermal conductivity is deteriorated, so that the temperature rises sharply and the wafer surface temperature increases.

Next, the case of manufacturing the electrostatic chuck device of the present invention will be described. First, a metal substrate provided with a slit-shaped hole having a predetermined shape is prepared, and an electrostatic chuck sheet having an adhesive applied to the back surface is provided thereon, and a slit-shaped cut portion is formed in a slit-shaped through hole of the metal substrate. Place so that it is positioned. Next, the slit-shaped cut portion is inserted into the slit-shaped hole, and the front end portion is bonded and fixed to the concave portion on the back surface of the metal base with an adhesive. Thereby, the electrostatic chuck device of the present invention having the exposed electrode layer on the back surface of the metal base can be manufactured.

In the electrostatic chuck device of the present invention, since the electrode layer of the sheet for electrostatic chuck is exposed on the back surface of the metal base, electric bonding can be performed directly on the electrode layer. Can be done.

[0027]

Next, examples of manufacturing the electrostatic chuck device of the present invention and an electrostatic chuck device for comparison will be described. All copies are on a weight basis. Production example [Production of sheet for electrostatic chuck] Polyimide film having a film thickness of 50 μm (Kapton 200H, manufactured by Toray DuPont)
A first adhesive layer adhesive having the following composition is applied to a first insulating layer made of
Dried at ° C. Polyamide resin 445.2 parts (Platabonda M-995, manufactured by Nippon Rilsan Co., Ltd.) High-purity epoxy resin 222.6 parts (Epicoat YL979, manufactured by Yuka Shell Co., Ltd.) Novolac phenolic resin 111.3 parts (Tamanol 752, manufactured by Arakawa Chemical Co., Ltd.) ) (Crosslinking agent) Dicyandiamide (manufactured by Wako Pure Chemical Industries, Ltd.) (Crosslinking accelerator) 0.57 parts

After drying, an electrolytic copper foil (1 / 20Z, manufactured by Nippon Mining Co., Ltd.) was bonded, and a step curing treatment at 40 to 160 ° C. was performed for 24 hours to obtain a negative photosensitive film (O
ZATEC-T538, manufactured by Hoechst Japan Co., Ltd.) was attached to the copper foil side. Exposure-development-etching-cleaning-
An electrode layer for the electrostatic chuck sheet was formed in a predetermined shape by a drying procedure. That is, in order to prevent the copper foil from being exposed in the formed electrostatic chuck sheet, a peripheral portion of the electrostatic chuck sheet and a portion of the copper foil to be cut to form a cut portion are removed by etching. Thus, no electrode layer was present in that portion.

On the other hand, another polyimide film (UPILEX 25S) is used as the second insulating layer, and an adhesive for the second adhesive layer having the same composition is applied to the polyimide film in the same manner as described above. It was pasted on the electrode layer made of the patterned copper foil and cured similarly. The total thickness of the obtained laminated sheet was 130 μm. This laminated sheet was formed according to the dimensions of the metal substrate. Further, a cut was made in a portion corresponding to the slit-shaped through-hole of the metal base to form a slit-shaped cut (length 70 mm, width 10 mm, width of electrode layer 7 mm). Further, a half punching process was performed on the tip of the cut portion to provide a half punched hole having a diameter of 2 mm, and an electrostatic chuck sheet having a diameter of 200 mm was manufactured.

[Production of Electrostatic Chuck Apparatus] First, an adhesive having the same composition as the adhesive for the adhesive layer was formed on a 30 mm-thick metal base having slit-shaped through holes. The sheet was pasted while performing positioning. At that time, the slit-shaped cut portion was inserted into the slit-shaped through-hole, and the tip portion of the slit-shaped cut portion was bonded to the concave portion on the back surface of the metal base with an adhesive. By curing these adhesives, an electrostatic chuck device having the structure shown in FIG. 1 was manufactured.

Comparative Production Example An electrostatic chuck device having the structure shown in FIG. 5 was produced as follows. [Preparation of Sheet for Electrostatic Chuck] Using the same materials as in the example, similarly, a first insulating layer, a first adhesive layer, an electrode layer, a second adhesive layer, and a second insulating layer were formed. A laminated sheet was produced. This laminated sheet was subjected to a forming process in accordance with the dimensions of the metal substrate, and was further subjected to a half punching process at a predetermined position to provide a half punched hole having a diameter of 2.0 mm to produce an electrostatic chuck sheet.

[Preparation of Power Feeding Sheet] An adhesive having the same composition as the first adhesive for the first adhesive layer was applied to an insulating layer made of a polyimide film (Kapton 200H, manufactured by Toray DuPont) having a thickness of 50 μm to a thickness of 10 μm. Apply so that it becomes 1
Dried at 70 ° C. Thereafter, a conductive layer for a power supply sheet was formed in a predetermined shape in the same procedure as that for forming the electrode layer of the electrostatic chuck sheet. On the other hand, another polyimide film (UPILEX 25S) was used, and an adhesive having the same composition as the first adhesive for the adhesive layer was applied thereto to form an adhesive layer. This was adhered on the conductive layer made of the copper foil formed as described above, and similarly cured.
The total thickness of the obtained laminated sheet was 130 μm.
With respect to this laminated sheet, a forming process is performed according to the dimensions of the concave portion and the slit-shaped through hole of the metal base, and a half punching process is further performed at a predetermined position to provide a half punched hole having a diameter of 2.0 mm, thereby producing a power supply sheet. did.

[Preparation of Electrostatic Chuck Apparatus] First, using an adhesive having the same composition as the adhesive for the above-mentioned adhesive layer, a power supply sheet was attached in a U-shape to the concave portion and the slit-shaped through hole of the metal base. I attached. Next, 1 mg of a conductive adhesive having the following composition was applied to the copper foil where the half-holes of the electrostatic chuck sheet and the power supply sheet were exposed, and degassing treatment was performed. Thereafter, the sheet for electrostatic chuck is adhered to the metal substrate using an adhesive having the same composition as the adhesive for the adhesive layer while performing alignment, and a curing treatment of the adhesive is performed. The electrostatic chuck device having the structure shown in FIG.

[Conductive adhesive] Epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd .; Epicoat # 828, epoxy equivalent: 190 g / eq) 7 parts Triglyceride trimellitate (manufactured by Shin Nippon Rika Co., Ltd .; Rica Resin TMTA, 50% methyl ethyl ketone solution) 7 parts 2-ethyl-4-methylimidazole 0.14 parts (manufactured by Shikoku Fine Chemical Co .; Curesol 2E4MZ) Silver powder (manufactured by Tokurika Chemical Laboratory; Silvet TCG-7) 75 parts butyl cellosolve 12 parts Knead with three rolls,
A conductive adhesive was obtained.

With respect to the electrostatic chuck devices of the above-mentioned production examples and comparative production examples, a DC voltage was applied to measure the static electricity generation voltage. The measurement conditions are as follows. Atmosphere: Atmospheric pressure (22 ° C., 54% RH), Power supply: DC positive polarity (10K
VDC generator, manufactured by Tokyo Transformer Co., Ltd., static electricity measuring device: Simco Electrostatic Locator SS-2 (manufactured by Simco Japan), measuring distance: 50 mm. 0V to 3
FIG. 4 shows a state of generation of static electricity when a DC voltage of KV is applied. As is clear from FIG. 4, according to the electrostatic chuck device of the present invention, it is found that a higher voltage static electricity is generated as compared with the comparative example.

[0036]

According to the present invention, in the electrostatic chuck device, the electrical connection is made directly to the electrode layer of the sheet for the electrostatic chuck on the back surface of the metal base. , A high static electricity generation voltage can be obtained, and therefore, the attraction force of the semiconductor wafer can be improved. In addition, since the structure is simple, the fabrication is easy.

[Brief description of the drawings]

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

FIG. 2 is a plan view of the electrostatic chuck sheet according to the present invention.

FIG. 3 is a schematic sectional view of a main part of the electrostatic chuck device in FIG.

FIG. 4 is a graph showing a relationship between an applied voltage and an amount of generated static electricity.

FIG. 5 is a schematic cross-sectional view of a main part for describing electrical connection of a conventional electrostatic chuck device. DESCRIPTION OF SYMBOLS 1 ... Metal base, 11 ... Through-hole, 12, 13 ... Depression, 2 ...
Electrostatic chuck sheet, 2a: cut portion, 21: first insulating layer, 22: first adhesive layer, 23: electrode layer, 23
a: exposed portion, 24: second adhesive layer, 25: second insulating layer, 3, 31, 32: adhesive layer, 4: power supply sheet, 41
... insulating layer, 42 ... adhesive layer, 43 ... conductive layer, 44 ... adhesive layer, 45 ... insulating layer, 5 ... conductive adhesive, 6 ... wafer.

Claims (1)

[Claims] 1. A slit-shaped through hole is provided in a thickness direction,
A metal substrate having a concave portion formed in a portion adjacent to the through hole on the back surface, and an electrostatic chuck sheet bonded to the metal substrate via an adhesive layer, wherein the electrostatic chuck sheet has Along the shape of the through hole, a slit-shaped cut portion having one end connected thereto is formed, and the cut portion penetrates the through hole of the metal base and adheres to the concave portion on the back surface with an adhesive, An electrostatic chuck device wherein a part of an electrode layer at a cut portion adhered to a concave portion is exposed.