JP2003292914A - Adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive film suitably usable as a process film for semiconductor wafers used in the back grinding and dicing of the wafers. <P>SOLUTION: The adhesive film is such one that an adhesive layer is provided on a substrate film bearing at least one layer comprising a styrene-based polymer constituent having syndiotactic structure. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-sensitive adhesive film, and more particularly to a pressure-sensitive adhesive film that can be suitably used as a pressure-sensitive adhesive film for fixing a semiconductor wafer used in a back grinding process or a dicing process of a semiconductor wafer.

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor wafer, first, a back-grinding process for polishing the opposite surface of a semiconductor wafer on which a predetermined circuit pattern is formed, and then, the polished and thinned semiconductor wafer is cut into individual IC chips. There is a dicing step of separating. In both of the above steps, a protective film adhered to the circuit surface of the semiconductor wafer is attached so as to prevent damage to the circuit surface and prevent the so-called chip jump from occurring during the dicing processing step. . Such a protective film that is adhesive processed,
Generally, a film for polishing a semiconductor wafer is called a back grinding film, and a film for cutting a semiconductor wafer into individual chips is called a dicing film.

In these protective films, the base material is subjected to an adhesive treatment for fixing the semiconductor wafer during processing, the adhesive effect is reduced after the processing, and further, the adhesive agent is applied to the semiconductor wafer, chips or the like. It is designed so that it can be peeled off so that there is no adhesive residue on the adhesive. As a form for facilitating peeling from the film after processing, a method of reducing adhesiveness by radiation curing, particularly ultraviolet curing, or addition of heat-expandable microspheres to the adhesive, a semiconductor wafer from the adhesive film, In the process of peeling off the chip, 1
There is a method in which the heat-expandable microspheres are foamed by heating to about 50 ° C. and the contact area with the adherend is reduced to reduce the tackiness.

However, as the pattern of semiconductor wafers has been improved in performance in recent years, the height difference of the unevenness on the wafer becomes large and the conventional adhesive design cannot follow the unevenness, and the adhesive effect on the wafer cannot be sufficiently obtained. Therefore, further improvement in adhesiveness is required. Further, in the pressure-sensitive adhesive to which the above-mentioned heat-expandable microspheres are added, a base material having inferior heat resistance may cause talumi in the film due to heating, and a heat resistant base material such as a biaxially stretched PET film is used. Since it does not have cushioning properties when used, it has been devised to increase the thickness of the adhesive and suppress the impact received during the process.However, increasing the thickness of the adhesive requires a great deal of time and effort in the adhesive application process However, there is a problem in that the selection of the composition content of the adhesive is restricted.

[0005]

SUMMARY OF THE INVENTION Therefore, the object of the present invention is to provide a heat-resistant base material which satisfies the back-grinding characteristics and dicing characteristics of a semiconductor wafer during semiconductor manufacturing and can be used in the heating step during the peeling step. To provide an adhesive film having

[0006]

DISCLOSURE OF THE INVENTION The present invention has found a tacky film capable of solving the above problems, and its gist is to provide a layer comprising a styrene polymer component having a syndiotactic structure. A pressure-sensitive adhesive film obtained by providing a pressure-sensitive adhesive layer on a base film having at least one layer. In a preferred embodiment of the present invention, 100 parts by weight of the styrene-based polymer having a syndiotactic structure in the styrene-based polymer having a syndiotactic polystyrene structure is added to at least a rubber-like elastic material as another material component. It is an adhesive film made of a styrene polymer composed of a resin component contained in an amount of 5 to 130 parts by weight.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The pressure-sensitive adhesive film of the present invention comprises a styrene-based polymer component containing a syndiotactic polystyrene structure which is a highly heat-resistant resin, and as a preferred form, 100 parts by weight of a styrene-based polymer having a syndiotactic structure, 5 to at least a rubber-like elastic body as a material component of
It is an adhesive film having at least one layer consisting of 130 parts by weight, more preferably 20 to 100 parts by weight of a resin component.

Here, the rubber-like elastic material means styrene-butadiene copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogen. Added styrene-butadiene-styrene block copolymer (S
EBS), styrene-isoprene block copolymer (S
EP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS) and the like. Further, a polymer component other than the above can be further added, and a general-purpose polymer such as polyethylene, polypropylene or polystyrene can be added as the thermoplastic resin.

Regarding the blending of the styrene-based polymer component containing the syndiotactic polystyrene structure and the rubber-like elastic component, 100 parts by weight of the styrene-based polymer having the syndiotactic structure is used, and at least the rubber is used as the other material component. The material composition of the resin component is 5 to 130 parts by weight, more preferably 20 to 100 parts by weight, and when the rubbery elastic component exceeds 130 parts by weight, styrene having a syndiotactic structure is obtained. The domain structure with the polymer is reversed and a phase transition occurs.
In this case, the phase having no heat resistance becomes the domain phase, and the film is likely to be tarmied in the heat treatment step.

The film forming method of the present invention is not particularly limited. For example, when the film is produced by an extrusion casting method, the material may be set at an extrusion cylinder temperature of 270 ° C. to 350 ° C. to form a film by hot melt extrusion. it can. Further, in the case of laminating and carrying at least one layer of components, an extrusion laminating method,
A laminated film may be formed into a film by a co-extrusion method using a feed block and a multi-manifold die. Furthermore, in order to improve the so-called expanding suitability, in which the film is uniformly stretched during the dicing step as the material constitution, and to improve the pick-up of the chip, it is preferable that the amount of rubber-like elasticity is large, and further, at least the laminate. Use of a material suitable for expanding in one layer enables suitable use. The thickness of the base material is not particularly limited, but the thickness can be appropriately determined according to the characteristics of the pressure-sensitive adhesive layer.

In order to obtain sufficient heat resistance, it is desirable to crystallize the syndiotactic polyolefin resin component, and the crystallization treatment may be performed by a known heat treatment device. For example, use a tenter device to heat-fix the film in a dryer, or use a heat-treatment roll at 150 ° C.
There is a method of performing heat treatment at around 220 ° C. If necessary, various additives may be added to or applied on the film of the present invention in order to impart functionality such as antistatic properties and slipperiness. Further, in order to obtain the mechanical strength of the film, it is possible to increase the strength by prescription such as stretching, for example, biaxial stretching. However, when shrinkage during heating becomes a problem, a method of increasing the heat setting temperature during stretching or a heat relaxation treatment after stretching can be performed, but a film is formed without stretching. Is also good.

The pressure-sensitive adhesive layer used in the pressure-sensitive adhesive film of the present invention usually contains a base polymer, a crosslinking agent, a photopolymerization initiator in the case of radiation crosslinking, and a tackifying resin. For the pressure-sensitive adhesive layer, most of those that cause a polymerization and curing reaction by ultraviolet rays and / or radiation are preferably used, but by adding a material (thermally expandable microspheres) that foams by heating, the peeling effect is improved. It can also be used. The addition of the foaming agent has the advantage that the time required for the peeling process can be shortened.

As the base polymer of the pressure-sensitive adhesive, an acrylic polymer is often used, and specifically, acrylic acid ester, methacrylic acid ester and their esters (hereinafter referred to as "(meth) acrylic acid ester") are used. And unsaturated monomers copolymerizable with the following polymers, acrylic acid, methacrylic acid and their esters, such as vinyl acetate, styrene and acrylonitrile. Examples of (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid. Isopropyl, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth)
Examples thereof include monomers such as nonyl acrylate and glycidyl (meth) acrylate.

Incidentally, the acrylic polymer has a COOH group serving as a reaction point (crosslinking point) with the crosslinking agent (meth).
It is preferable to have 1 to 5% by weight of a reactive monomer such as acrylic acid or 2-hydroxyethyl (meth) acrylate having an OH group, and its molecular weight is 20.
Those in the range of 10,000 to 800,000 are preferable.
When the molecular weight of the acrylic polymer is less than 200,000, it is difficult to maintain sufficient cohesive force of the pressure-sensitive adhesive layer, and 80
If it exceeds 10,000, the melt viscosity at the time of polymerization becomes too high, and the handling tends to be difficult. To reduce the viscosity, it is possible to dilute by adding a solvent, but it requires a large amount of solvent and is not economical. The above-mentioned photopolymerization initiator is excited by irradiation with ultraviolet rays, activated to generate radicals, and added at the same time, trimethylolpropane triacrylate, pentaerythritol triacrylate, polyethylene glycol diacrylate, oligoester acrylate, etc. In addition, it has a function of curing a curing agent such as an acrylic resin compound having at least two UV and / or radioactive polymerizable carbon-carbon double bonds by radical polymerization.

Specifically, for example, 4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2.
-Methyl-1-phenylpropan-1-one, 1- (4
-Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl)
2-hydroxy-2-methylpropan-1-one, 4
Such as-(2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 Acetophenone photopolymerization initiator, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin photopolymerization initiator such as 2,2-dimethoxy-2-phenylacetophenone,

Benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4 '.
-Methyldiphenyl sulfide, benzophenone-based photopolymerization initiators such as 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4 Thioxanthone-based photopolymerization initiators such as dichlorothioxanthone, 2,4-diethylthioxanthone and 2,4-diisopropylthioxanthone, α-acyloxime ester,
Specific photopolymerization initiators such as acylphosphine oxide, methylphenylglyoxylate, benzyl, camphorquinone, dibenzosuberone, 2-ethylanthraquinone, 4 ′, 4 ″ -diethylisophthalophenone can be used.

In the present invention, a crosslinking agent may be added, if desired, in order to impart a sufficient cohesive force to the pressure-sensitive adhesive layer. The cross-linking agent can three-dimensionally cross-link the acrylic polymer, and can further impart sufficient cohesive force to the pressure-sensitive adhesive layer. As the cross-linking agent, known ones such as polyisocyanate compound, polyglycidyl compound, aziridine compound, melamine compound, polyvalent metal chelate compound and the like can be used. The mixing ratio when adding the cross-linking agent is 0.05 parts by weight or more and less than 15 parts by weight, especially 0.1 part by weight based on 100 parts by weight of the acrylic polymer.
It is preferably in the range of not less than 12 parts by weight and not less than 12 parts by weight.
If the blending ratio of the cross-linking agent is less than 0.05 parts by weight, the effect of adding the cross-linking agent is difficult to obtain, and if it is more than 15 parts by weight, it becomes excessive and remains in the pressure-sensitive adhesive layer. This is not preferable because it easily causes contamination of the chip.

Further, a tackifying resin is added to the pressure-sensitive adhesive layer in order to maintain a suitable balance of the pressure-sensitive adhesive force and the cohesive force before and after irradiation with ultraviolet rays and / or radiation. Examples of the tackifying resin include rosin resin, rosin ester resin, terpene resin, terpene phenol resin, phenol resin, xylene resin, coumarone resin, coumarone indene resin, styrene resin, aliphatic petroleum resin, aromatic petroleum resin, Examples thereof include aliphatic aromatic copolymer-based petroleum resins, alicyclic hydrocarbon resins, and modified products, derivatives, and hydrogenated products thereof, but are not particularly limited, and are compatible with acrylic polymers. Can be appropriately selected in consideration of the above.

The action of the heat-expandable microspheres added to enhance the peeling effect is used to expand the heat-expandable microspheres and reduce the contact area with the adherend. Any microsphere in which the material described above is included in the core of an elastic body may be used, and for example, Microsphere (trade name) manufactured by Matsumoto Yushi-Seiyaku Co., Ltd. can be preferably used.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but it is preferably about 5 to 30 μm. In the present invention, a pressure-sensitive adhesive layer is formed on the base material, and in order to produce a dicing film for a semiconductor wafer, the components constituting the pressure-sensitive adhesive layer are used as they are, or they are solubilized with an appropriate organic solvent, and applied or sprayed. It can be obtained by coating on a base material by, and drying by heat treatment, for example, at 80 to 100 ° C. for about 30 seconds to 10 minutes. In addition, when the pressure-sensitive adhesive is applied to the base material, the base material can be surface-treated as necessary, and the application can be further facilitated by performing corona treatment, easy adhesion treatment, or the like. is there.

When the adhesive sheet of the present invention is used as a background film for a semiconductor wafer, it can be polished without warping. Further, when used as a dicing film, it can be used by a known method. For example, after the dicing film for a semiconductor wafer is attached and fixed to a semiconductor wafer, the semiconductor wafer is cut with a rotary round blade into element pieces (chips). Disconnect. After that, by irradiating ultraviolet rays and / or radiation from the base material side of the pressure-sensitive adhesive sheet for processing, if necessary heat-treating, and picking up a small element (chip) by a method such as adsorption with a vacuum collet or air tweezers. Just mount them at the same time.

[0022]

EXAMPLES The effects of the present invention will be clarified below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. As for the evaluation method, practical evaluation was carried out on three items of back grind suitability, dicing suitability and heat resistance based on the characteristics of the semiconductor manufacturing process.

Evaluation method (1) A 6-inch wafer adhered to the back grind aptitude was ground by a grinding machine (DFC manufactured by Disco Corporation).
G-840), 6 inch wafer 725 μm 1
The warp of the wafer after cutting to 00 μm and grinding was measured, and there was almost no warp (excellent) (∘), good one (∘), warp but no problem in use (△ ), And those with a large amount of warp that cannot be used are marked with (x).

(2) Dicing aptitude The 6-inch wafer adhered is set to a depth of 20 μm in the sheet with a 25 μm diamond blade, and 3.
Full cut into 1 mm square chips. At this time, the presence or absence of chip fly was observed. Very good with no chip fly (⊚), good (○) without chip fly but with unstable cutting condition (△), with chip fly (×) ).

(3) After heat resistant dicing, 80 W / from a distance of 10 cm from the substrate surface.
The pressure-sensitive adhesive layer was cured by irradiating it with ultraviolet rays for 15 seconds using a cm high-pressure mercury lamp, and heat-treated for 40 seconds on a 140 ° C. hot plate. Then cool to room temperature,
At this time, the slack of the adhesive film for fixing was measured. As a result, a very good product with almost no slack (◎),
Good ones (○), some slack, but those that do not cause problems in the subsequent pickup process (△),
There was slack, and it was made unusable (x) in the subsequent pickup process.

(4) Pickup Appropriate Vacuum Pyramid collet was used to measure the number of chips that could not be picked up when 200 chips were picked up.
Further, the chip around the pick-up location was visually observed for scattering and scattering. There were no pick-up mistakes, chip disturbance and scattering were not recognized, and the pick-up properties were extremely good (◎), and those with good pick-up properties (○), there were no pick-up errors and scattering was not recognized. Disturbances were indicated by (Δ), and pickup errors, chip disturbances, and scattering were observed (×).

(5) Comprehensive Evaluation All of the evaluations were good, and there was no problem as an adhesive film for fixing semiconductor wafers (chips), and the results were extremely good (⊚) and good (○), The one which has some problems but can be used is indicated by (Δ), and the one which cannot be used as an adhesive film for fixing a semiconductor wafer (chip) due to a problem is indicated by (x).

Preparation of adhesive layer Obtained by copolymerizing 50 parts by weight of 2-ethylhexyl acrylate, 10 parts by weight of butyl acrylate, 37 parts by weight of vinyl acetate and 3 parts by weight of 2-hydroxyethyl methacrylate. With respect to 100 parts by weight of a copolymer (acrylic polymer) having a weight average molecular weight of 500,000, the molecular weight is 25,
000 multifunctional urethane acrylate oligomer 69
Parts by weight, 2,2-dimethoxy-2- as a photopolymerization initiator
8 parts by weight of phenylacetophenone based on 100 parts by weight of polyfunctional urethane acrylate oligomer, softening point 1
Acrylic polymer 100 was prepared by combining an aliphatic-aromatic copolymer petroleum resin having a molar ratio of aliphatic: aromatic of 6: 4 at 00 ° C.
14 parts by weight, 7 parts by weight of a polyisocyanate-based crosslinking agent based on 100 parts by weight of an acrylic polymer, and heat-expandable microspheres (Matsumoto Microsphere F-3).
01D / Matsumoto Yushi-Seiyaku Co., Ltd.) PE resin having a thickness of 38 μm, which is obtained by peeling a resin solution forming an adhesive layer containing 10 parts by weight.
T film (“DIAFOIL T-100-30” manufactured by Mitsubishi Kagaku Polyester Film Co., Ltd.) has a thickness of 10 after drying.
The pressure-sensitive adhesive layer was prepared by coating and drying so as to have a thickness of μm.

Example 1 A polystyrene resin having a syndiotactic structure (Zarek 130A, manufactured by Idemitsu Petrochemical Co., Ltd.) was extruded at a cylinder temperature of 2.
An amorphous sheet having a thickness of 100 μm was prepared by hot melt extrusion at 70 ° C. to 300 ° C., and the film was heat set in a dryer at 180 ° C. using a tenter device to obtain a crystallized film. This base film was laminated with the release film with an adhesive obtained as described above to prepare an adhesive film with an adhesive for fixing a semiconductor wafer (chip). The obtained adhesive film for fixing a semiconductor wafer (chip) was aged at room temperature for 7 days or more, and then adhered to a semiconductor wafer, and the above evaluation was carried out in a back grinding process and a dicing process which are semiconductor processes.

Example 2 A hydrogenated styrene-butadiene-styrene block copolymer (manufactured by Kuraray Co., Ltd.) as a rubber-like elastic material was added to 100 parts by weight of a polystyrene resin having a syndiotactic structure (Idemitsu Petrochemical Co., Ltd .: Zarek 130A). Septon 2104)
An adhesive film for fixing a semiconductor wafer (chip) was prepared in the same manner as in Example 1 except that a base material containing 5 parts by weight of was used, and the same evaluation as in Example 1 was performed. .

Example 3 A hydrogenated styrene-butadiene-styrene block copolymer (manufactured by Kuraray Co., Ltd.) as a rubber-like elastic material was added to 100 parts by weight of a polystyrene resin having a syndiotactic structure (Idemitsu Petrochemical Co., Ltd .: Zarek 130A). Septon 2104)
An adhesive film for fixing a semiconductor wafer (chip) was prepared in the same manner as in Example 1 except that a base material compounding 20 parts by weight was used, and the same evaluation as in Example 1 was performed. .

Example 4 A hydrogenated styrene-butadiene-styrene block copolymer (manufactured by Kuraray Co., Ltd.) as a rubber-like elastic material was added to 100 parts by weight of a polystyrene resin having a syndiotactic structure (Idemitsu Petrochemical Co., Ltd .: Zarek 130A). Septon 2104)
An adhesive film for fixing a semiconductor wafer (chip) was prepared in the same manner as in Example 1 except that a base material containing 50 parts by weight of was used, and the same evaluation as in Example 1 was performed. .

Example 5 A hydrogenated styrene-butadiene-styrene block copolymer (manufactured by Kuraray Co., Ltd.) as a rubber-like elastic material was added to 100 parts by weight of a polystyrene resin having a syndiotactic structure (Idemitsu Petrochemical Co., Ltd .: Zarek 130A). Septon 2104)
An adhesive film for fixing a semiconductor wafer (chip) was prepared in the same manner as in Example 1 except that the base material was mixed in an amount of 100 parts by weight, and the same evaluation as in Example 1 was performed. .

Example 6 A hydrogenated styrene-butadiene-styrene block copolymer (manufactured by Kuraray Co., Ltd.) as a rubber-like elastic material was added to 100 parts by weight of a polystyrene resin having a syndiotactic structure (Idemitsu Petrochemical Co., Ltd .: Zarek 130A). Septon 2104)
An adhesive film for fixing semiconductor wafers (chips) was prepared in the same manner as in Example 1 except that the base material was added in an amount of 130 parts by weight, and the same evaluation as in Example 1 was performed. .

Example 7 A hydrogenated styrene-butadiene-styrene block copolymer (manufactured by Kuraray Co., Ltd.) as a rubber-like elastic material was added to 100 parts by weight of a polystyrene resin having a syndiotactic structure (Idemitsu Petrochemical Co., Ltd .: Zarek 130A). Septon 2104)
An adhesive film for fixing a semiconductor wafer (chip) was prepared in the same manner as in Example 1 except that the base material was mixed in an amount of 140 parts by weight, and the same evaluation as in Example 1 was performed. .

Comparative Example 1 An adhesive film for fixing a semiconductor wafer (chip) was prepared in the same manner as in Example 1 except that a soft vinyl chloride material was used as the base material to obtain a base film. The same evaluation as was performed.

Comparative Example 2 An adhesive film for fixing a semiconductor wafer (chip) was prepared in the same manner as in Example 1 except that a base film was obtained using a low density polyethylene material, and the same evaluation as in Example 1 was performed. Was carried out. Tables 1 and 2 show the results of evaluation of the above Examples / Comparative Examples.

[0038]

[Table 1]

[0039]

[0040]

The adhesive film of the present invention is highly applicable as an adhesive film for fixing a semiconductor wafer (chip) after the back grinding process and the dicing process of the semiconductor wafer (chip).

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Claims (3)

[Claims] 1. An adhesive film comprising a base film having at least one layer comprising a styrene polymer component having a syndiotactic structure and a pressure-sensitive adhesive layer provided on the base film. 2. A rubber-like elastic body is added in an amount of 5 to 1 with respect to 100 parts by weight of a styrene-based polymer having a syndiotactic structure.
The pressure-sensitive adhesive film according to claim 1, comprising a base film containing 30 parts by weight. 3. The adhesive film according to claim 1, which is used in a back grinding process or a dicing process of a semiconductor wafer.