JP2008045091A - Pressure-sensitive adhesive sheet for processing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressure-sensitive adhesive sheet for processing excellent in adhesiveness, peelability and expandability. <P>SOLUTION: The adhesive sheet 11 for processing is an adhesive sheet 11 for processing containing at least a base material 12 constituted by containing soft vinyl chloride and an adhesive layer 13 characterized in that it contains a radiation polymerizable compound having at least 2 or more light reactive functional groups in one molecule. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a processing pressure-sensitive adhesive sheet used for processing such as dicing on a workpiece such as a semiconductor wafer.

  A semiconductor wafer made of silicon, germanium, gallium-arsenide, or the like is manufactured in a large diameter state, and then an adhesive sheet is bonded to the back surface (the surface opposite to the circuit pattern forming surface), and dicing and cleaning are performed in that state. , Drying, expanding, pick-up, and mounting are performed.

  In recent years, the adhesive sheet used in the semiconductor wafer dicing process has sufficient adhesive force from the dicing process to the expanding process, and the adhesive in the adhesive sheet does not adhere to the chip at the time of pickup. What has power is desired.

  As such pressure-sensitive adhesive sheets, for example, the following Patent Documents 1 and 2 are pressure-sensitive adhesive sheets coated with a pressure-sensitive adhesive composed of a low molecular weight compound having at least two photopolymerizable carbon-carbon double bonds in the molecule. In addition, there has been proposed a structure in which a pressure-sensitive adhesive layer (adhesive layer) can be formed into a three-dimensional network when light is applied to a substrate surface made of polyvinyl chloride.

  However, the pressure-sensitive adhesive sheets disclosed in Patent Documents 1 and 2 have the following problems. That is, when the pressure-sensitive adhesive sheet is used after long-term storage, the radiation-polymerizable compound present in the pressure-sensitive adhesive layer moves into the base material made of polyvinyl chloride. In some cases, the content of the adhesive compound decreases, and the curing reaction of the pressure-sensitive adhesive layer becomes insufficient. As a result, there is a problem that the peelability is lowered even when UV is irradiated, and the adhesive adheres to the chip when the chip is picked up.

  Moreover, when the plasticizer which exists in a base material transfers in an adhesive layer, an adhesive layer is often softened. For this reason, there is a problem that even if an attempt is made to pick up a semiconductor chip after UV irradiation, the pick-up cannot be performed reliably. Further, there is a problem that the adhesive strength of the adhesive sheet is lowered before UV irradiation.

  Here, the adhesive sheet which prevented this with respect to transfer of the plasticizer from a base material into an adhesive layer is disclosed by the following patent document 3, for example. That is, an intermediate layer is provided between the base resin sheet as the base material and the pressure-sensitive adhesive layer, thereby effectively suppressing the migration of the plasticizer from the base material to the pressure-sensitive adhesive layer. As the intermediate layer, a resin layer selected from polyethylene, polypropylene, polyalkylene terephthalate and modified alkyd resin is used. However, the pressure-sensitive adhesive sheet described in Patent Document 3 does not sufficiently suppress the migration of various additives such as anti-aging agents. As a result, there is a problem that the stretchability of the pressure-sensitive adhesive sheet in the expanding step and the restoring property after expanding are lowered, and the base material is bent.

JP-A-60-196956 JP 60-223139 A JP-A-1-56111

  This invention is made | formed in view of the said problem, The objective is to provide the adhesive sheet for a process excellent in adhesiveness, peelability, and expandability.

  The inventors of the present application have made extensive studies on the pressure-sensitive adhesive sheet for processing in order to solve the conventional problems. As a result, it was found that the object can be achieved by adding a component having a predetermined weight average molecular weight in the radiation polymerizable compound constituting the pressure-sensitive adhesive layer, and the present invention has been completed.

  That is, the processing pressure-sensitive adhesive sheet according to the present invention is a processing pressure-sensitive adhesive sheet having at least a base material and a pressure-sensitive adhesive layer in order to solve the above-described problems, and the base material includes soft vinyl chloride, The pressure-sensitive adhesive layer contains a radiation polymerizable compound having at least two photoreactive functional groups in one molecule.

  According to the above configuration, when curing the radiation-polymerizable compound by irradiating the pressure-sensitive adhesive layer, the curing function of the pressure-sensitive adhesive layer is suppressed from being extremely reduced, and the pressure-sensitive adhesive layer is peelable. Can be maintained in a good state. Therefore, even when the processing pressure-sensitive adhesive sheet having the above-described configuration is used, for example, for processing a semiconductor wafer, it is possible to prevent generation of adhesive residue and to exhibit good peelability.

  The radiation polymerizable compound preferably includes a radiation polymerizable component having a weight average molecular weight of 750 or more.

  According to the said structure, it can prevent that a radiation polymerizable compound transfers in the base material containing a soft vinyl chloride also in the tape storage for a long period of time. As a result, it is possible to maintain the function of exhibiting a large adhesive force before irradiation with radiation and reducing the adhesive force after irradiation with radiation for a long period of time.

  The radiation polymerizable component is preferably contained in an amount of 40% by weight or more.

  As described above, by setting the content of the radiation polymerizable component having a weight average molecular weight of 750 or more to 40% by weight, the curing function of the pressure-sensitive adhesive layer can be further lowered even when used after long-term storage. And extremely good peelability can be maintained in an optimal state.

  The pressure-sensitive adhesive layer preferably comprises a pressure-sensitive adhesive in which 10 parts by weight or more of a radiation polymerizable compound is blended with 100 parts by weight of the base polymer.

  According to the said structure, it can prevent that a radiation polymerizable compound transfers in the base material containing a soft vinyl chloride also in the tape storage for a long period of time. As a result, it is possible to maintain the function of exhibiting a large adhesive force before irradiation with radiation and reducing the adhesive force after irradiation with radiation for a long period of time.

  An intermediate layer is provided between the base material and the pressure-sensitive adhesive layer, and the intermediate layer prevents a predetermined additive in the base material from being transferred into the pressure-sensitive adhesive layer. It is preferable that it is a layer which prevents transfer of the radiation polymerization initiator and radiation polymerizable compound in a base material.

  By setting it as the said structure, it can prevent that additives, such as a plasticizer, transfer into an adhesive layer from the base material comprised including soft vinyl chloride. As a result, it is possible to prevent a decrease in adhesiveness due to softening due to a decrease in cohesive force of the pressure-sensitive adhesive layer. In addition, since the intermediate layer can also prevent the radiation polymerizable compound, the radiation polymerization initiator, and the like from migrating from the pressure-sensitive adhesive layer into the base material, it can maintain the curing function of the pressure-sensitive adhesive layer by irradiation with radiation. It can prevent that peelability falls. Furthermore, with the above structure, the block function is exhibited not only for plasticizers but also for various additives such as anti-aging agents, thus preventing extensibility during the expansion process and deterioration of restoration properties after expansion. it can. Thereby, it can prevent that bending generate | occur | produces in the adhesive sheet for a process.

  The peel adhesive strength before irradiation is preferably 7 N / 20 mm width or more, and the peel adhesive strength after radiation irradiation is preferably 0.35 N / 20 mm width or less.

  With the above-described configuration, the workpiece can be reliably fixed before the irradiation with radiation, and can be peeled off satisfactorily without causing any adhesive residue at the time of peeling after the irradiation.

The present invention has the following effects by the means described above.
That is, in the processing pressure-sensitive adhesive sheet according to the present invention, the radiation-polymerizable compound in the pressure-sensitive adhesive layer can be prevented from migrating into the base material. Can be suppressed as much as possible. As a result, it is possible to provide a processing pressure-sensitive adhesive sheet with reduced adhesive residue and excellent peelability.

  In addition, between the base material and the pressure-sensitive adhesive layer, the plasticizer and the anti-aging agent present in the base material, the radiation polymerizable compound and the radiation polymerization initiator, etc. present in the pressure-sensitive adhesive layer are respectively the pressure-sensitive adhesive layer or the base. By providing an intermediate layer that prevents migration into the material, it is possible to provide a pressure-sensitive adhesive sheet for processing that can prevent deterioration of adhesiveness and expandability due to softening of the adhesive layer and bending of the base material. Play.

(Embodiment 1)
Embodiment 1 of the present invention will be described below with reference to the drawings. However, parts that are not necessary for the description are omitted, and some parts are illustrated by being enlarged or reduced for easy explanation.

  FIG. 1 is a schematic cross-sectional view illustrating a schematic configuration of a processing pressure-sensitive adhesive sheet (hereinafter simply referred to as a pressure-sensitive adhesive sheet) according to the first embodiment. As shown in the figure, the pressure-sensitive adhesive sheet 11 according to the present embodiment includes a base material 12 and a pressure-sensitive adhesive layer 13.

  The base 12 is a support base for the pressure-sensitive adhesive layer 13 and is made of a film containing soft vinyl chloride. The substrate 12 may be composed of a single layer or may be composed of a laminate of two or more layers. When the substrate 12 is a laminate of two or more layers, at least one layer may be a soft vinyl chloride film. The substrate 12 has a property of transmitting at least part of radiation such as X-rays, ultraviolet rays, and electron beams in order to cure the pressure-sensitive adhesive layer 13 by radiation. Moreover, what has the softness | flexibility which can endure the expanding after dicing is preferable.

  The constituent material of the substrate 12 is not particularly limited. For example, polyvinyl chloride, urethane-vinyl chloride copolymer, ethylene-vinyl chloride copolymer, vinyl acetate-vinyl chloride copolymer, ethylene-acetic acid. Examples thereof include vinyl chloride copolymers such as vinyl copolymers and mixtures thereof, or mixtures with other resins and elastomers. The copolymer includes a kraft copolymer and the mixture includes a so-called alloy.

  In addition to the above-mentioned constituent materials, the base material 12 includes low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolymer. Polypropylene, polybutene, polyolefins such as polymethylpentene, ionomer resin, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer, Polymers such as ethylene-hexene copolymer, polyurethane, polyester such as polyethylene terephthalate, polyimide, polyether ether ketone, polyvinylidene chloride, fluororesin, cellulosic resin, and cross-linked products thereof were blended as required. Also It can also be used.

  Additives such as phthalic acid esters such as dibutyl phthalate, dioctyl phthalate, dinonyl phthalate, diisodecyl phthalate, other polyester plasticizers, epoxy plasticizers, or trimet plasticizers are added to the base material 12. May be. The epoxy plasticizer may be epoxidized soybean oil as a secondary plasticizer and stabilizer.

  Further, in the base material 12, softeners such as mineral oil, fillers such as calcium carbonate, silica, talc, mica, clay, antioxidants, light stabilizers, antistatic agents, lubricants, dispersants, neutralization Various known additives such as an agent, an α crystal nucleating agent, a β crystal nucleating agent, a processing aid, and an antiaging agent may be blended as necessary.

  The base material 12 may be used without stretching or may be subjected to uniaxial or biaxial stretching treatment as necessary. The surface of the substrate 12 can be subjected to conventional physical or chemical treatment such as mat treatment, corona discharge treatment, primer treatment, and crosslinking treatment (chemical crosslinking (silane)) as necessary. The thickness of the substrate 12 (total thickness in the case of a laminate of two or more layers) is not particularly limited, and is preferably about 50 to 250 μm, more preferably about 70 to 230 μm. .

  The substrate 12 can be formed by a conventionally known film forming method. Specifically, for example, a wet casting method, an inflation extrusion method, a T-die extrusion method, or the like can be used.

  The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 13 is not particularly limited, and a conventionally known pressure-sensitive adhesive can be used, but an acrylic pressure-sensitive adhesive is preferred in the present embodiment. Specifically, a copolymer with an acrylic polymer or other functional monomer selected from a homopolymer and a copolymer having an acrylate ester as a main constituent monomer unit, and a mixture of these polymers Is preferred.

  As the acrylate ester, butyl methacrylate, 2-ethylhexyl methacrylate, glycidyl methacrylate, 2-hydroxyethyl methacrylate, etc., and those obtained by changing the methacrylic acid to acrylic acid, for example, are also preferable. Can be used. As such an adhesive polymer, various polymers such as rubber-based, acrylic-based, silicone-based and vinyl ester-based are used. Among these adhesive polymers, acrylic polymers are particularly preferable from the viewpoint of cleanability of electronic components that are not subject to contamination such as semiconductor wafers and glass with an organic solvent such as ultrapure water or alcohol.

  Examples of the acrylic polymer include (meth) acrylic acid alkyl esters (for example, methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, s-butyl ester, t-butyl ester, pentyl ester, Isopentyl ester, hexyl ester, heptyl ester, octyl ester, 2-ethylhexyl ester, isooctyl ester, nonyl ester, decyl ester, isodecyl ester, undecyl ester, dodecyl ester, tridecyl ester, tetradecyl ester, hexadecyl ester , Octadecyl ester, eicosyl ester, etc., alkyl groups having 1 to 30 carbon atoms, especially 4 to 18 carbon atoms, such as linear or branched alkyl esters) Beauty (meth) acrylic acid cycloalkyl esters (e.g., cyclopentyl ester, cyclohexyl ester, etc.), etc. One or acrylic polymer using two or more of the monomer component can be exemplified.

  In addition, the above (meth) acrylic acid alkyl ester and other copolymerizable monomers, such as (meth) acrylic acid hydroxyalkyl ester (hydroxyethyl ester, hydroxybutyl ester, hydroxyhexyl ester, etc.), (meth) acrylic Acid glycidyl ester, (meth) acrylic acid, itaconic acid, maleic anhydride, (meth) acrylic acid amide, (meth) acrylic acid N-hydroxymethylamide, (meth) acrylic acid alkylaminoalkyl ester (dimethylaminoethyl ester, T-butylaminoethyl ester, etc.), vinyl acetate, styrene, acrylonitrile and the like are also used. In addition, (meth) acrylic acid alkyl ester means acrylic acid alkyl ester and / or methacrylic acid alkyl ester, and (meth) in the present invention has the same meaning.

  Furthermore, since the acrylic polymer is crosslinked, a polyfunctional monomer or the like can be included as a monomer component for copolymerization as necessary. Examples of such polyfunctional monomers include hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, Pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, urethane (meth) Examples include acrylates. These polyfunctional monomers can also be used alone or in combination of two or more. The amount of the polyfunctional monomer used is preferably 30% by weight or less of the total monomer components from the viewpoint of adhesive properties and the like.

  The acrylic polymer can be obtained by subjecting a single monomer or a mixture of two or more monomers to polymerization. The polymerization can be performed by any method such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization and the like. As for the molecular weight of the acrylic polymer, the weight average molecular weight is usually 200,000 or more, preferably 300,000 to 2,000,000, more preferably 500,000 to 1,500,000. Moreover, the glass transition temperature of this acrylic polymer is usually 0 ° C. or less, preferably about −100 ° C. to −20 ° C., so as to exhibit adhesiveness at ordinary temperature (23 ° C.).

  In addition, an external cross-linking agent can be appropriately employed for the pressure-sensitive adhesive in order to increase the weight average molecular weight of an acrylic polymer as a base polymer. Specific examples of the external crosslinking method include a method in which a so-called crosslinking agent such as a polyisocyanate compound, an epoxy compound, an aziridine compound, or a melamine crosslinking agent is added and reacted. When using an external cross-linking agent, the amount used is appropriately determined depending on the balance with the base polymer to be cross-linked and further depending on the intended use as an adhesive. In general, it is preferable to blend about 5 parts by weight or less, and further 0.1 to 5 parts by weight with respect to 100 parts by weight of the base polymer. In addition to the above-mentioned components, additives such as various conventionally known tackifiers and anti-aging agents may be used for the pressure-sensitive adhesive, if necessary.

  The pressure-sensitive adhesive layer 13 according to the present embodiment contains a radiation polymerizable compound. When the radiation-polymerizable compound is contained in the pressure-sensitive adhesive layer 13, the radiation-polymerizable compound is polymerized by irradiation with radiation, and the pressure-sensitive adhesive force of the pressure-sensitive adhesive layer 13 can be reduced. Further, the radiation polymerizable compound includes a radiation polymerizable compound component having a weight average molecular weight of 750 or more, more preferably a weight average molecular weight of about 1000 to 10,000. When such a radiation-polymerizable compound component is contained, a sufficient adhesive force can be maintained, so that chip fly can be prevented from occurring during dicing of the semiconductor wafer. Further, when picking up a chip, a good pick-up is possible without generating adhesive residue.

  In the present invention, a compound having a photoreactive functional group of at least 2 or more, preferably 3 to 6 in one molecule is used as the radiation polymerizable compound. As said photoreactive functional group, photopolymerizable functional groups, such as a urethane acrylate group, are mentioned, for example. Examples of such a radiation-polymerizable compound having two or more photoreactive functional groups in one molecule include those disclosed in Japanese Patent Application Laid-Open No. 60-196956 and Japanese Patent Application Laid-Open No. 60-223139. And low molecular weight compounds having at least two photopolymerizable carbon-carbon double bonds in the molecule, which can be three-dimensionally reticulated by irradiation with radiation such as ultraviolet rays and electron beams. More specifically, for example, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, or 1,4-butylene glycol Examples include diacrylate, 1,6-hexanediol diacrylate, and commercially available oligoester acrylate.

  In addition to this, a urethane acrylate oligomer can also be used as the radiation polymerizable compound. As such a urethane acrylate oligomer, when a weight average molecular weight of 500 to 40,000, preferably 750 to 30,000 is used, an adhesive adheres to the chip surface even when the semiconductor chip is picked up even when the semiconductor wafer surface is rough. Can be prevented.

  The amount of the radiation polymerizable compound is preferably, for example, about 10 parts by weight or more and more preferably 20 to 140 parts by weight with respect to 100 parts by weight of the base polymer such as an acrylic polymer constituting the pressure-sensitive adhesive. preferable. Further, the content of the radiation-polymerizable compound component having a weight average molecular weight of 750 or more is preferably 40% by weight or more, and more preferably 50 to 100% by weight.

The pressure-sensitive adhesive layer 13 according to the present embodiment may contain a radiation polymerization initiator in order to be cured by radiation such as ultraviolet rays. As the radiation polymerization initiator, the molar extinction coefficient at 365 nm, which is a characteristic wavelength of a high-pressure mercury lamp generally used in the manufacturing process of semiconductor devices, is 1,000 mol ⁻¹ · cm ⁻¹ or more, preferably 1,500 mol ^{−. 1} · cm ⁻¹ or more (usually 30,000 mol ⁻¹ · cm ⁻¹ or less) and a maximum absorption wavelength on the long wavelength side of 420 nm or more, preferably 430 nm or more (usually 460 nm or less) are used. . Specific examples include 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide. It is done. In addition, 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α′-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, 1 Α-ketol compounds such as hydroxycyclohexyl phenyl ketone; methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1- [4- (methylthio)- Acetophenone compounds such as phenyl] -2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether and anisoin methyl ether; ketal compounds such as benzyldimethyl ketal; 2-naphthalenesulfonyl chloride Aromatic sulfonyl chloride compounds such as: 1-phenone-1,1-propanedione-2- (o-ethoxycarbonyl) oxime and other photoactive oxime compounds; benzophenone, benzoylbenzoic acid, 3,3′-dimethyl- Benzophenone compounds such as 4-methoxybenzophenone; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2, Examples include thioxanthone compounds such as 4-diethylthioxanthone and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketone; acyl phosphinoxide; acyl phosphonate.

  The compounding quantity of a radiation polymerization initiator is about 20-140 weight part with respect to 100 weight part of base polymers, such as an acryl-type polymer which comprises an adhesive.

  The pressure-sensitive adhesive sheet 11 according to the present embodiment can be suitably used for processing a semiconductor (Si, Ge, Ga-As, etc.) wafer, for example. That is, for example, the adhesive sheet 11 is bonded to a circuit pattern forming surface of a semiconductor wafer, and the semiconductor wafer is diced to produce a semiconductor chip. Thereafter, the adhesive sheet 11 is irradiated with radiation to pick up a semiconductor chip. Here, since the pressure-sensitive adhesive sheet 11 according to the present embodiment continues to maintain a sufficient curing function against radiation irradiation, it can be easily peeled off without causing adhesive residue on the semiconductor chip. Excellent in properties. Moreover, since the adhesive layer 13 continues to maintain a sufficient curing function against radiation irradiation, it is excellent in long-term storage.

(Embodiment 2)
Another embodiment of the pressure-sensitive adhesive sheet for processing a semiconductor wafer of the present invention will be described with reference to FIG. In addition, the description is abbreviate | omitted about the member to which the member number similar to the member number attached | subjected to the member used in the said embodiment was attached | subjected.

  FIG. 2 is a schematic cross-sectional view illustrating a schematic configuration of the pressure-sensitive adhesive sheet according to the second embodiment. As shown in the figure, the adhesive sheet 21 according to the second embodiment is provided with an intermediate layer 22 between the substrate 12 and the adhesive layer 13 as compared with the adhesive sheet according to the first embodiment. Is different.

  The intermediate layer 22 has a function as a transition prevention layer that blocks various additives such as a plasticizer and an anti-aging agent contained in the substrate 12 from migrating into the pressure-sensitive adhesive layer 13. By preventing the migration of the plasticizer or the like, it is possible to prevent the pressure-sensitive adhesive layer 13 from being softened and the pressure-sensitive adhesive force from being lowered. In addition, it is possible to prevent a decrease in peelability due to softening of the pressure-sensitive adhesive layer 13 after irradiation with radiation. Further, it also has a function of blocking the migration of the radiation polymerization initiator and the radiation polymerizable compound contained in the pressure-sensitive adhesive layer 13 into the substrate 12. Thereby, when the adhesive layer 13 is irradiated with radiation, it is possible to prevent the curing reaction of the radiation polymerizable compound from becoming insufficient, and to prevent the peelability from being lowered.

  The material used for the intermediate layer 22 is excellent in solvent resistance, does not dissolve or swell in plasticizers and various stabilizers contained in soft vinyl chloride, and can be easily restored by appropriate heating even after elongation. Resin that can be used is used. Examples of such materials include polymethyl methacrylate and polyvinyl alcohol. Moreover, as a method of laminating the intermediate layer 22 on the substrate 12, a conventionally known method such as co-extrusion, extrusion lamination, thermal lamination, dry lamination, solution casting, or the like can be employed.

  The thickness of the intermediate layer 22 is not particularly limited, and is preferably 1 to 15 μm, and more preferably 3 to 10 μm. When the thickness is within the above range, it is possible to reduce the occurrence of chipping on the back surface of the chip during dicing of the semiconductor wafer.

  In addition, you may form another layer between the intermediate | middle layer 22 and the base material 12 for the purpose of improving adhesiveness and blocking the transfer component from the adhesive layer 13 or the base material 12. FIG. . Examples of such other layers include those made of polypropylene, polymethyl methacrylate, and the like.

  The adhesive sheet 21 according to the present embodiment can be suitably used for processing a semiconductor wafer or the like, as in the first embodiment. Moreover, since the adhesive sheet 21 which concerns on this Embodiment suppresses the fall of adhesiveness, workpieces, such as a semiconductor wafer, can be fixed reliably. For this reason, chipping or chip jumping during dicing can be prevented, and damage to the semiconductor wafer or the like can be reduced. Furthermore, since the softening of the pressure-sensitive adhesive layer 13 is also prevented, the peelability is excellent, so that it is possible to easily pick up a semiconductor chip or the like without causing adhesive residue. Furthermore, since the migration of the anti-aging agent or the like in the base material 12 to the pressure-sensitive adhesive layer 13 can be prevented, sufficient extensibility is maintained even during the expanding step, and the restoring property after expanding is also good.

(Other matters)
In the above description, the most preferred embodiment of the present invention has been described. However, the present invention is not limited to this embodiment, and various modifications can be made within the scope substantially the same as the technical idea described in the claims of the present invention.

  That is, the processing pressure-sensitive adhesive sheet of the present invention may have a structure in which a release layer is laminated thereon for protecting the pressure-sensitive adhesive layer. As a peeling layer, what consists of conventionally well-known plastic films (polyethylene terephthalate, polypropylene, etc.), paper, nonpolar materials (polyethylene, polypropylene, etc.), etc. are mentioned. Further, the release layer may be subjected to release treatment such as silicone treatment, long-chain alkyl treatment, and fluorine treatment. Thereby, an adhesive sheet can be wound and made into tape shape. Although the thickness of a peeling layer is not specifically limited, Usually, 10-200 micrometers, Preferably it is about 25-100 micrometers.

  The pressure-sensitive adhesive sheet for processing according to the present invention is not limited to the processing of the semiconductor wafer, and is suitable as a pressure-sensitive adhesive sheet for dicing such as a semiconductor package or glass.

  Moreover, the shape of the processing pressure-sensitive adhesive sheet according to the present invention can take any shape such as a tape shape and a label shape.

  Hereinafter, preferred embodiments of the present invention will be described in detail by way of example. However, the materials, blending amounts, and the like described in the examples are not intended to limit the scope of the present invention only to them, but are merely illustrative examples, unless otherwise specified. In the following, “parts” means parts by weight.

(Preparation of UV-reactive oligomer)
The molecular weight of the UV-reactive oligomer was adjusted as follows. First, UV-1700B (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was used as a UV-reactive oligomer, and each component having a predetermined molecular weight was separated using a GPC column. That is, a UV reactive oligomer having a weight average molecular weight of less than 750 was designated as oligomer A, and a UV reactive oligomer having a weight average molecular weight of 750 or more was designated as oligomer B.

  Further, UV-3000B (trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was mixed with UV-1700B so as to have a mixing ratio of 2: 1. When the molecular weight of the oligomer C was measured with a GPC column, the UV-reactive oligomer having a weight average molecular weight of 750 or more was 62% by weight.

  In addition, the weight average molecular weight of the final UV-reactive oligomer after preparation was confirmed by performing GPC analysis after dissolving each UV-reactive oligomer in a THF solution. The apparatus and measurement conditions used for GPC analysis are as follows.

Analysis device: HLC-8120GPC manufactured by TOSOH
Column: TSKgel SuperHM-H / H4000 / H3000 / H2000
Column size: 6.0 ml. D. × 150mm
Eluent: THF
Flow rate: 0.6ml / min
Detector: RI
Column temperature: 40 ° C

(Example 1)
50 parts of methyl acrylate, 20 parts of 2-ethylhexyl acrylate and 5 parts of acrylic acid were copolymerized by a conventional method to obtain a solution containing an acrylic polymer having a weight average molecular weight of 1,200,000. To 100 parts of this solution, 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name “Irgakiure 651” manufactured by Ciba Specialty Chemicals Co., Ltd.) as a photopolymerization initiator, molar absorption at a light wavelength of 365 nm was used. 3 parts of a coefficient of 150 mol ⁻¹ · cm ⁻¹ and a long wavelength side maximum absorption wavelength of 400 nm) and 2 parts of a melamine-based crosslinking agent were added. Furthermore, the oligomer B was added so that it might become 60 parts, and the ultraviolet curable adhesive composition was obtained.

  This solution was applied to a soft vinyl chloride film (base material) having a thickness of 100 μm, heated at 80 ° C. for 10 minutes, dried and crosslinked to form an ultraviolet curable pressure-sensitive adhesive layer having a thickness of 5 μm. Thereby, the adhesive sheet A which concerns on the present Example 1 was produced.

(Example 2)
The present embodiment is different in that an oligomer C is used in place of the oligomer B used in the first embodiment. The pressure-sensitive adhesive sheet obtained in this example was referred to as pressure-sensitive adhesive sheet B.

(Comparative Example 1)
This comparative example is different in that the oligomer A is used in place of the oligomer B used in the first embodiment. The pressure-sensitive adhesive sheet obtained in this comparative example was named pressure-sensitive adhesive sheet C.

(Evaluation)
Each pressure-sensitive adhesive sheet of Examples 1 and 2 and Comparative Example 1 was stored for 6 months, and then peeled adhesive strength before and after ultraviolet irradiation was measured by the following method.

<Peeling adhesion test>
A sample piece was cut out of the adhesive sheet with a width of 20 mm × 12 cm in the flow direction, attached to a silicon mirror wafer, and allowed to stand for about 30 minutes, and the peel adhesive strength before ultraviolet irradiation was measured. Moreover, after irradiating with ultraviolet rays under the following irradiation conditions, the peel adhesion was measured. The measurement conditions were: measuring device: Tensilon (manufactured by Orientec), tensile speed: 300 mm / min, peeling angle: 90 °.

<Irradiation conditions>
A high-pressure mercury lamp was used as the light source, and the irradiation intensity was 50 mW / cm ² (measuring instrument: “UV illuminance meter / UT101” manufactured by Ushio), and the irradiation time was 20 seconds.

<Pickup property>
Using a dicing machine (DFD-651 manufactured by Disco), a silicon mirror wafer to which the adhesive sheets A, B and a are bonded together is rotated at a dicing speed of 80 m / min and a rotational speed of a dicing blade (2050HFDD manufactured by Disco). r. p. m. The adhesive sheet was cut at a depth of 15 μm and cut into 10 mm × 10 mm chips.

  Then, when a diced 10 mm × 10 mm chip is picked up with a die bonder (CPS-100 (Nichiden Machinery)) at a needle push-up speed of 30 mm / sec, the adhesive adheres to the back surface of the chip, that is, there is no adhesive residue. It was confirmed. Confirmation of the adhesive residue was performed by visual observation or observation with a microscope (50 to 500 times). The pickup was performed after irradiating with ultraviolet rays under the irradiation conditions.

<Expandability>
The expandability of each of the pressure-sensitive adhesive sheets A, B, and a was also evaluated. That is, 2-6-1 (made by Disco, inner diameter 19.5 cm) was used as the dicing ring, CPS-100 (made by NEC Machine) was used as the die bonder, and the chip distance was evaluated with the amount of withdrawal being 13 mm. The case where it was 10 mm or more was evaluated as ◯.

  As is clear from Table 1, the adhesive strengths of the adhesive sheets according to Examples 1 and 2 before UV irradiation were 10.42 N / 20 mm width and 8.50 N / 20 mm width, respectively. On the other hand, the adhesive force before UV irradiation of the adhesive sheet according to Comparative Example 1 was 6.00 N / 20 mm width. On the other hand, the adhesive strengths after UV irradiation of the adhesive sheets according to Examples 1 and 2 were 0.25 N / 20 mm width and 0.15 N / 20 mm width, respectively. On the other hand, the adhesive force after UV irradiation of the adhesive sheet according to Comparative Example 1 was 0.83 N / 20 mm width. Thus, the pressure-sensitive adhesive sheets according to Examples 1 and 2 contain a sufficient amount of radiation polymerization initiator in each pressure-sensitive adhesive layer even after UV irradiation, and maintain a predetermined peeling performance. confirmed.

  Further, when the adhesive residue on the silicon mirror wafer was examined, no adhesive residue was found when the adhesive sheets A and B were used, but when the adhesive sheet C was used, the adhesive residue was confirmed. From these results, when the adhesive sheet C which concerns on a comparative example is used, it has shown that a pick-up defect may be caused at the time of the pick-up of a semiconductor chip. On the other hand, when the pressure-sensitive adhesive sheets A and B according to Examples 1 and 2 are used, it is considered that good pickup properties are exhibited.

  Moreover, about expandability, with the adhesive sheet A of Example 1 and the adhesive sheet B of Example 2, it showed sufficient extensibility, and it was confirmed that the base material is not bent. On the other hand, with respect to the pressure-sensitive adhesive sheet C of Comparative Example 1, tape breakage occurred when the amount of withdrawal was 8 mm.

It is a cross-sectional schematic diagram which shows schematic structure of the adhesive sheet for a process which concerns on Embodiment 1 of this invention. It is a cross-sectional schematic diagram which shows schematic structure of the adhesive sheet for a process which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Processing adhesive sheet 12 Base material 13 Adhesive layer 21 Adhesive sheet (processing adhesive sheet)
22 Middle layer

Claims (6)

A pressure-sensitive adhesive sheet for processing having at least a base material and a pressure-sensitive adhesive layer,
The substrate comprises soft vinyl chloride,
The pressure-sensitive adhesive layer contains a radiation-polymerizable compound having at least two or more photoreactive functional groups in one molecule.   The pressure-sensitive adhesive sheet for processing according to claim 1, wherein the radiation-polymerizable compound includes a radiation-polymerizable component having a weight average molecular weight of 750 or more.   The pressure-sensitive adhesive sheet for processing according to claim 1 or 2, wherein the radiation polymerizable component is contained in an amount of 40% by weight or more. The pressure-sensitive adhesive layer is
The pressure-sensitive adhesive for processing according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive contains 10 parts by weight or more of a radiation polymerizable compound with respect to 100 parts by weight of the base polymer. Sheet. An intermediate layer is provided between the base material and the pressure-sensitive adhesive layer,
The intermediate layer prevents the predetermined additive in the base material from being transferred into the pressure-sensitive adhesive layer, and allows the radiation polymerization initiator and the radiation polymerizable compound in the pressure-sensitive adhesive layer to be transferred into the base material. It is a layer to prevent, The processing adhesive sheet of any one of Claims 1-4 characterized by the above-mentioned.   The peel adhesive strength before radiation irradiation is 7 N / 20 mm width or more, and the peel adhesive strength after radiation irradiation is 0.35 N / 20 mm width or less. The processing pressure-sensitive adhesive sheet according to item.

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