JP2008140823A - Electrostatic chuck - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic chuck having sufficient durability. <P>SOLUTION: An electrode sheet 30 is constituted by bonding an insulating organic film 31 and a resin film 32 via an insulating adhesive agent layer 33 and by forming electrodes 34, 35 within the layer of the insulating adhesive agent layer 33. This electrode sheet 30 is characterized in that an upper surface of the insulating organic film 32 as the uppermost surface layer can adsorb a substance to be adsorbed and the resin film 32 has the property for recovery through heating. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electrostatic chuck device that holds, for example, a semiconductor wafer or a glass substrate by suction.

  In semiconductor manufacturing, a chuck device that sucks and holds a wafer is used to fix the wafer at a predetermined position of a processing apparatus such as a plasma etching apparatus. Among them, the electrostatic chuck device has an advantage that it is easy to handle and can be used in a vacuum. Conventional electrostatic chuck devices have, for example, a structure in which a pair of insulating organic films are attached via an insulating adhesive layer containing electrodes (Patent Document 1), or a pair of ceramic substrates sandwiching the electrodes Structures are known.

JP 2004-235563 A

  However, the electrostatic chuck device is liable to cause scratches on the outermost layer in contact with the object to be attracted due to rubbing when the wafer is attached or detached.

  When the outermost layer is scratched, the internal electrode of the electrostatic chuck device is liable to cause dielectric breakdown and the durability is lowered.

  The present invention has been made in view of the above situation, and an object thereof is to provide an electrostatic chuck device having excellent durability.

  The electrostatic chuck device according to the present invention is characterized in that a resin film having resilience is used as the outermost layer in contact with the object to be adsorbed. An epoxy acrylate resin is preferable as the material of the resin film. The electrostatic chuck device of the present invention is characterized in that the outermost layer in contact with the object to be adsorbed contains an epoxy acrylate resin.

  ADVANTAGE OF THE INVENTION According to this invention, the electrostatic chuck apparatus excellent in durability can be provided.

  An embodiment of an electrostatic chuck device according to the present invention will be described with reference to the drawings. 1 to 3 are cross-sectional views when the electrostatic chuck device of the present embodiment is cut in a direction perpendicular to the extending direction of the electrodes. For convenience of explanation, the side that adsorbs the object to be adsorbed is defined as the upper side, and the opposite side is defined as the lower side.

  As shown in FIG. 1, the electrostatic chuck device 10 according to the present embodiment includes an insulating organic film 31 and a resin film 32 attached via an insulating adhesive layer 33, and a strip-like shape in the insulating adhesive layer 33. The electrode sheet (electrostatic chuck device electrode sheet) 30 on which the internal electrodes 34 and 35 are formed is mainly composed of the electrode sheet 30 adhered to the substrate 20 through the adhesive layer 21. is there. In the present embodiment, the upper surface of the resin film 32 is an adsorption surface that adsorbs an object to be adsorbed.

  The positions of the internal electrodes 34 and 35 in the insulating adhesive layer 33 are shown in FIGS. As shown in FIG. 3A, a structure that contacts the insulating organic film 31, or a structure that does not contact either the insulating organic film 31 or the resin film 32, as shown in FIG. Alternatively, as shown in FIG. 3C, a structure in contact with the resin film 32 is also possible.

  FIG. 2 shows another shape of the present embodiment. The difference from FIG. 1 is that an insulating layer 36 and an adhesive layer 37 are interposed between the insulating adhesive layer 33 and the resin film 32, and are functionally the same as those in FIG. In addition, about the layer structure of an electrostatic chuck apparatus, it is not limited to the said layer structure, What is necessary is just the layer containing the resin film or epoxy acrylate resin which has a restoring property in the outermost layer. Further, the electrostatic chuck device may be the electrode sheet 30 itself without the adhesive layer 21 and the substrate 20.

  For the outermost layer in contact with the object to be adsorbed, a resin film 32 having resilience is used. “Restorability” means that even if a scratch is generated on the surface of the resin film, the scratch disappears by heating, for example, and the surface is restored.

  The material for the resin film is preferably an epoxy acrylate resin. Examples of the epoxy acrylate resin in the present invention include a vinyl ester resin obtained by reacting a general bisphenol type or alicyclic epoxy compound with (meth) acrylic acid. In particular, a resin obtained by curing a mixture of one or a plurality of monomers and a polymerization initiator selected from the vinyl ester resin and a vinyl compound or an allyl compound with light (UV light) or heat is preferable. Used.

  The vinyl ester resin is a vinyl ester resin produced by reacting a bisphenol type or alicyclic epoxy compound with (meth) acrylic acid. As the epoxy compound, a reaction product of bisphenol A and epichlorohydrin, bisphenol F and Reaction product of epichlorohydrin, reaction product of hydrogenated bisphenol A and epichlorohydrin, reaction product of cyclohexanedimethanol and epichlorohydrin, reaction product of norbornane dialcohol and epichlorohydrin, reaction product of tetrabromobisphenol A and epichlorohydrin, tricyclodecane dimethanol and epichlorohydrin Reactants, alicyclic diepoxy adipate, alicyclic diepoxy carbonate, alicyclic diepoxy acetal, alicyclic diepoxy Po carboxylates, and the like.

  Moreover, as said vinyl compound and an allyl compound, general things, such as an allyl ester monomer, an acrylate ester monomer, a methacrylic ester monomer, a styrene monomer, (alpha) -methyl styrene monomer, an acrylonitrile monomer, can be used, for example. Specifically, as the allyl ester monomer, diallyl orthophthalate, diallyl isophthalate, diallyl terephthalate, diallyl 1,4-cyclohexanedicarboxylate, diallyl succinate or the like can be used. Examples of acrylic acid ester monomers and methacrylic acid ester monomers include methyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, EO adduct dimethacrylate of bisphenol A, and EO of bisphenol A. Adduct diacrylate, polyethylene glycol dimethacrylate, polyethylene glycol diacrylate, 1,6-hexanediol diacrylate, phenoxyethyl methacrylate, isobornyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, dicyclopentenyloxyethyl acrylate, dicyclopentenyloxy Ethyl methacrylate, trimethylolpropane di Chlorate, trimethylolpropane dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane tris-oxyethylene acrylate, trimethylolpropane tris-oxyethylene methacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipenta Erythritol hexaacrylate, glycerin diacrylate, glycerin dimethacrylate, 2,6-dibromo-4-tertiary butylphenyl acrylate, and the like can be used.

In order to cure the epoxy acrylate resin in the present invention, photocuring and thermal curing are useful.
Examples of the photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, benzophenone, and 2-methyl-1- (4-methylthiophenyl) -2. -Monofolinopropane-1,2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 and the like.
In the case of thermosetting, organic peroxides such as dialkyl peroxide, acyl peroxide, hydroxy peroxide, ketone peroxide, and peroxy ester are used.

  The thickness of the resin film made of the epoxy acrylate resin in the present invention is preferably 10 to 300 μm, and more preferably 20 to 200 μm. If this thickness is less than 10 μm, there will be a problem in film strength. On the other hand, if it exceeds 300 μm, it will be difficult to wind in the film state, the distance from the electrode to the object to be adsorbed will be increased, and good adsorption performance will be obtained. It is not preferable because it is difficult to obtain. The resin film of the present invention preferably has a pencil hardness of F or higher. Furthermore, the resin film of the present invention preferably has oil resistance.

  In addition, the resin film made of the epoxy acrylate resin in the present invention is a mixture of a vinyl ester resin and one or more monomers selected from vinyl compounds or allyl compounds and a polymerization initiator. It can be obtained by sandwiching with a base material or the like and curing by applying heat or light (UV light).

  Furthermore, for the purpose of improving hardness, adhesiveness, durability, weather resistance, light resistance, water resistance, corrosion resistance, etc., the resin film has an ultraviolet absorber, a near infrared absorber, a light stabilizer, and a light scattering agent. Various additives such as an antioxidant, an antifoaming agent, a leveling agent, a thixotropy imparting agent, an internal mold release agent, an ion scavenger, a lubricant, and a coupling agent can be added.

The material of the insulating organic films 31 and 36 in FIGS. 1 and 2 is not particularly limited, but examples thereof include polyesters such as polyethylene terephthalate, polyolefins such as polyethylene, polyimide, polyamide, polyamideimide, and polyethersalt. Examples include phonon, polyphenylene sulfide, polyether ketone, polyether imide, triacetyl cellulose, and silicone rubber. Of these, polyesters, polyolefins, polyimide, silicone rubber, polyetherimide, polyethersulfone and the like are preferable because of excellent insulation. Particularly preferred is polyimide. The polyimide film is commercially available. For example, trade name Kapton manufactured by Toray DuPont, trade name Upilex manufactured by Ube Industries, and trade name Apical manufactured by Kaneka Chemical Co., Ltd. are preferably used.
The thickness of the insulating organic films 31 and 36 is not particularly limited, but is preferably 20 to 150 μm, and more preferably 25 to 75 μm.

In the present embodiment, the insulating adhesive layer 33 is made of an insulating adhesive having an insulation resistance of a differential voltage of 5 kV or more in the insulation resistance test. The insulating adhesive is formed by patterning a plurality of internal electrodes having a width of 1 mm and a thickness of 5 μm on an insulating organic film so as to have a total length of 5 m with an electrode interval of 1 mm, and an insulating adhesive having a thickness of 10 μm thereon. An electrode sheet for evaluation in which an agent layer is formed and an insulating organic film is further adhered is formed, and when a differential voltage of 5 kV is applied to the electrodes of the electrode sheet for evaluation, it has an insulation resistance that does not cause a short circuit between the electrodes. .
Insulating adhesives having this property include epoxy resins, phenol resins, polyamide resins, acrylonitrile-butadiene copolymers, polyester resins, polyimide resins, silicone resins, styrene block copolymers, amine compounds, bismaleimide compounds, etc. A material satisfying the conditions can be selected and used from an adhesive mainly composed of one or more resins selected from the above.
Epoxy resins include bisphenol, phenol novolac, cresol novolac, glycidyl ether, glycidyl ester, glycidylamine, trihydroxyphenylmethane, tetraglycidylphenolalkane, naphthalene, diglycidyldiphenylmethane, and diglycidyl. Specific examples include bifunctional or polyfunctional epoxy resins such as biphenyl type. Among these, bisphenol type epoxy resins are preferable, and bisphenol A type epoxy resins are particularly preferable. When epoxy resin is the main component, curing agents for epoxy resins such as imidazoles, tertiary amines, phenols, dicyandiamides, aromatic diamines, organic peroxides, and curing accelerators are used as necessary. What mix | blended the agent can also be used.
Specific examples of the phenol resin include novolak phenol resins such as alkylphenol resins, p-phenylphenol resins, and bisphenol A type phenol resins, resole phenol resins, polyphenylparaphenol resins, and the like.
Examples of the styrene block copolymer include styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-butylene-styrene block copolymer (SEBS), Specific examples include styrene-ethylene-propylene-styrene copolymer (SEPS).

  The internal electrodes 34 and 35 are not particularly limited as long as the internal electrodes 34 and 35 are made of a conductive material capable of exhibiting an electrostatic adsorption force when a voltage is applied, but copper, aluminum, gold, silver, platinum, chromium, nickel, tungsten It is preferable to pattern a thin film made of one or more metals selected from the above or their alloys. Specific examples of the metal thin film include a film formed by vapor deposition, plating, sputtering, etc., a film formed by applying and drying a conductive paste, a metal foil such as a copper foil, and the like.

  Although it does not specifically limit as the board | substrate 20 which adheres the electrode sheet 30, An aluminum substrate, a stainless steel board | substrate, a ceramic board | substrate etc. are mentioned.

  As the adhesive constituting the adhesive layers 21 and 37, the same adhesive as that of the insulating adhesive layer 33 can be used. However, the adhesive layers 21 and 37 do not need high insulation resistance as required for the insulating adhesive layer 33.

  According to the electrode sheet 30 and the electrostatic chuck device 10 of the present embodiment, since a resin film having resilience is employed for the resin film 32 in contact with the object to be adsorbed, heating is performed even if a flaw occurs. As a result, the scratches on the resin film 32 disappear, and restoration properties are obtained. By obtaining resilience, dielectric breakdown is less likely to occur, and an electrostatic chuck device having excellent durability can be realized.

EXAMPLES Next, although this invention is demonstrated in more detail using an Example, this invention is not limited to these Examples.
(Preparation of epoxy acrylate resin film)
The following materials were added to a 1 liter flask equipped with a thermometer, a stirrer, a distillation condenser, and a gas introduction tube, and reacted at 120 to 125 ° C. for 2 hours while blowing nitrogen gas.
Bisphenol A diepoxy compound 374.4 g
Methacrylic acid 206.4g
Chromium octylate 1.5g
Phosphorous acid 0.15g
Hydroquinone 0.2g
Thereafter, when the acid value reached 11.0, the flask contents were transferred to a metal vat and cooled to obtain Resin A.

Next, the following materials were uniformly dissolved and mixed, and bubbles were removed with a vacuum deaerator.
Resin A 70 parts by weight Methyl methacrylate 10 parts by weight Styrene 20 parts by weight N-nitrosophenylhydroxyamine aluminum salt 0.003 parts by weight 1,1,3,3-trimethylbutylperoxy-2-ethylhexanate
1.5 parts by weight

  Next, the above-mentioned mixture was filled in two flat glass plates with PET films having a thickness of 100 μm sandwiched at the four corners, and was put into a 130-degree oven for 5 minutes to be thermally cured. Further, after cooling at room temperature, the glass was removed to obtain an epoxy acrylate resin film.

(Production of electrostatic chuck device)
An electrode sheet and an electrostatic chuck device having the structure shown in FIG. 1 were produced as follows.
A polyimide film having a film thickness of 50 μm (trade name Kapton manufactured by Toray DuPont) is used for the insulating organic film 31 in FIG. Copper was plated with a thickness of 5 μm on one side of the polyimide film, and a photoresist was applied to the surface of the copper foil. Development was performed after pattern exposure, and unnecessary copper foil was removed by etching. Thereafter, the copper foil on the polyimide film was washed to remove the photoresist and form an internal electrode. An insulating adhesive sheet (acrylonitrile-butadiene rubber: made by Nippon Zeon Co., Ltd., trade name: Nippon Pole 1001 100 parts by mass) corresponding to the insulating adhesive layer 33 in FIG. , High purity epoxy resin: 50 parts by mass of Epicote YL979 manufactured by Yuka Shell Co., Ltd., cresol type phenol resin: 50 parts by mass of CKM2400 manufactured by Showa Polymer Co., Ltd., 5 parts by mass of 2 ethyl 4-methylimidazole: manufactured by Wako Pure Chemical Industries, Ltd. 1 was mixed and dissolved in an appropriate amount of methyl ethyl ketone), and then an epoxy acrylate resin film was adhered and adhered by heat treatment to obtain an electrode sheet 30 of FIG. In addition, the thickness of the adhesive bond layer 33 in FIG. 1 after drying was 20 μm.
An insulating adhesive sheet (acrylonitrile-butadiene rubber: Nippon Zeon Co., Ltd.) which is semi-cured by drying and heating on the lower surface of the electrode sheet 30 (the lower surface of the polyimide film) corresponding to the adhesive layer 21 Product name Nippon 1001 100 parts by mass, high-purity epoxy resin: Yuka Shell Co., Ltd. product name Epicoat YL979 50 parts by mass, cresol type phenol resin: Showa Kogyo Co., Ltd. Product name CKM2400 50 parts by mass, 2-ethyl 4-methylimidazole : 5 parts by mass of Wako Pure Chemical Industries, Ltd. mixed and dissolved in an appropriate amount of methyl ethyl ketone) was laminated, adhered to the aluminum substrate 20, and adhered by heat treatment. In addition, the thickness of the adhesive bond layer 21 in FIG. 1 after drying was 20 μm.

(Comparative Example 1)
An electrostatic chuck apparatus of Comparative Example 1 was produced in the same manner as Example 1 except that a polynorbornene film (trade name: Zeonore ZF14, manufactured by Optis Corporation) was used instead of the epoxy acrylate resin film.

(Comparative Example 2)
An electrostatic chuck device of Comparative Example 2 was produced in the same manner as in Example 1 except that a polyimide film (trade name Kapton manufactured by Toray DuPont Co., Ltd.) was used instead of the epoxy acrylate resin film.

(Evaluation)
The electrostatic chuck apparatus obtained as described above was evaluated for its resilience and electrical characteristics, and the results are shown in Table 1.
(1) Restorability Using steel wool # 0000, the surface of the epoxy acrylate resin obtained in Example, the surface of the polynorbornene film obtained in Comparative Example 1, and the polyimide film obtained in Comparative Example 2 The surface was rubbed back and forth 10 times at a load of 250 g to give scratches to the surface.
Thereafter, the electrostatic chuck device was heated at 120 ° C. for 5 minutes, and the restoration property of the surface was visually confirmed.
(2) Electrical characteristics In the electrostatic chuck apparatus after the evaluation of resilience, DC voltage ± 3.0 kV was applied ON for 2 minutes, and application ON / OFF for 30 seconds was repeated 1000 times to check for dielectric breakdown.

As shown in Table 1, the scratches on the epoxy acrylate resin surface in the examples disappeared by heating, and no scars were confirmed. On the other hand, many flaws were confirmed after heating on the surface of the polynorbornene film in Comparative Example 1 and the surface of the polyimide film in Comparative Example 2, and no restoring property was observed. Therefore, it was confirmed that the restoring property of the example is superior to the conventional electrostatic chuck devices (Comparative Examples 1 and 2).
Moreover, as shown in the electrical characteristics of Table 1, no dielectric breakdown was observed in the examples. In contrast, dielectric breakdown was observed in Comparative Example 1 and Comparative Example 2. Therefore, it was confirmed that the electrical characteristics of the examples were superior to the conventional electrostatic chuck devices (Comparative Examples 1 and 2).

  As described above in detail, according to the present invention, an electrostatic chuck device having excellent durability can be provided.

It is sectional drawing which shows the embodiment of the electrostatic chuck apparatus which concerns on this invention. It is sectional drawing which shows the embodiment of the electrostatic chuck apparatus which concerns on this invention. It is a fragmentary sectional view showing an example of arrangement of an internal electrode of an example of an embodiment concerning the present invention.

Explanation of symbols

10 Electrostatic chuck device 30 Electrode sheets 31, 36 Insulating organic film 32 Resin film 33 Insulating adhesive layers 34, 35 Internal electrodes

Claims (3)

  An electrostatic chuck apparatus, wherein an outermost layer in contact with an object to be adsorbed is a resin film having resilience.   2. The electrostatic chuck device according to claim 1, wherein the resin film is made of an epoxy acrylate resin.   An electrostatic chuck device, wherein the outermost layer in contact with the object to be adsorbed contains an epoxy acrylate resin.

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