JP2007305680A - Dicing die bond sheet for laser dicing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dicing die bond sheet for laser dicing which can be peeled off even after a wafer is cut by laser dicing. <P>SOLUTION: In the dicing die bond sheet for laser dicing, a pressure sensitive adhesive layer and an adhesive layer for bonding a wafer are laminated sequentially on a substrate film. Diffuse reflectance is 10% or above at 355 nm when light is irradiated from the pressure sensitive adhesive layer toward the substrate film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a dicing die-bonding sheet used when a wafer with an adhesive is divided into chips by laser dicing.

  In recent years, the need for miniaturization of mounted components has further increased, and the miniaturization technology for semiconductor packaging has been evolving. As a result, semiconductor chips are also required to be made thinner and smaller, and at the same time, technical needs for compact packaging of these thin and small semiconductor chips will continue to increase. Conventionally, these semiconductor chips are obtained by forming a semiconductor wafer that has been ground and thinned in the back grinding process into a chip in the dicing process. Further, a necessary amount of a liquid adhesive is applied to a continuously flowing lead frame for each die bonding by a pick-up die bonder or the like, and the resulting semiconductor chip is die-bonded at that position.

Of these processes, in a dicing process, a semiconductor wafer (hereinafter sometimes referred to simply as a wafer) is generally bonded with a dicing tape, fixed to a chuck table of a dicer with a ring frame, and then cut with a blade. It is. At this time, a cutting resistance by the blade is applied to the wafer, so that a small chip or crack (hereinafter referred to as chipping) may occur in the separated semiconductor chip (hereinafter sometimes referred to simply as a chip). This occurrence of chipping has recently been regarded as one of the important problems, and various studies have been made to reduce chipping so far, but there is still no satisfactory means.
Furthermore, this chipping tends to occur as the wafer becomes thinner, and the allowable level of chipping becomes stricter with a small chip. Therefore, as described above, as the tendency of the semiconductor chip to become thinner and smaller is further advanced, it is easily assumed that this chipping problem will become more serious in the future.

Further, the separated semiconductor chip is required to be compactly packaged while preventing chipping. This comes from the need to reduce the package size, and it is desired that the package is desirably made to be approximately the same size as the size of the semiconductor chip.
For such a problem, the adhesive layer and the dicing tape are pasted on the base film without the need for two pasting steps of pasting the film adhesive and the dicing tape, and further pasting it on the back side of the semiconductor wafer. A technique for producing a dicing die-bonding sheet in which adhesive layers are sequentially provided in this order, affixing this to a wafer, performing dicing, and then leaving the adhesive layer on the wafer side to obtain an element piece with adhesive. It has been proposed (Patent Document 1).

A dicing sheet for supporting and fixing the workpiece when cutting the workpiece using a laser beam as a method for preventing the occurrence of chipping and compact packaging, including a support sheet It consists of a base material and an adhesive layer arranged on one side surface of the base material, wherein the adhesive layer can be cut by the laser beam, and the support sheet cannot be cut by the laser beam. A dicing sheet is disclosed. According to this method, an element piece with an adhesive can be obtained, and the workpiece is cut with a laser beam, so that chipping is low (Patent Document 2).
WO2005 / 088700 JP 2002-343747 A

The technique shown in Patent Document 1 is only required to be able to be peeled off at the interface between the adhesive and the pressure-sensitive adhesive so that no component of the pressure-sensitive adhesive remains on the adhesive side. When laser dicing was performed, it was found that the components of the pressure sensitive adhesive transferred to the adhesive due to the heat generated by the laser irradiation, and could not be successfully peeled off at the interface between the adhesive and the pressure sensitive adhesive.
This invention is made | formed in view of such a subject, Comprising: The dicing die-bonding sheet | seat for laser dicing which can be peeled even if it cut | disconnects a wafer by laser dicing is provided.

As a result of intensive studies in view of the above problems, the present inventors have found that the following dicing die bond sheet is suitable for the purpose.
That is, the present invention
(1) A dicing die bond sheet for laser dicing in which a pressure-sensitive adhesive layer and a wafer fixing adhesive layer are sequentially laminated on a base film, and light is irradiated from the pressure-sensitive adhesive layer toward the base film. A dicing die bond sheet for laser dicing, characterized in that the diffuse reflectance at 355 nm is sometimes 10% or more,
(2) The dicing die bond sheet for laser dicing according to (1), wherein the light transmittance at 355 nm of the pressure-sensitive adhesive layer is 80% or more,
(3) The dicing die bond sheet for laser dicing according to (1) or (2), wherein the adhesive layer has a light transmittance at 355 nm of 80% or less,
Is to provide.

  According to the dicing die bond sheet for laser dicing of the present invention, when the laser is irradiated and divided into chips, the wafer fixing adhesive layer and the adhesive layer are fused by heat generated during laser irradiation. Without doing so, a chip having an adhesive layer formed on the back surface can be obtained.

In the dicing die bond sheet for laser dicing of the present invention, a pressure-sensitive adhesive layer and a wafer fixing adhesive layer are sequentially laminated on a base film. Hereinafter, each material constituting each layer will be described.
(Base film)
The base film which comprises the dicing die bond sheet for laser dicing of this invention is demonstrated. In the present invention, any material can be used without particular limitation as long as it has a function of holding a wafer as a workpiece, but it is not cut by the laser beam irradiated when laser dicing is performed. Those having a high laser beam transmittance are preferred.

  Examples of polymers that can be selected as such a substrate include polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentene-1, ethylene-vinyl acetate copolymer, ethylene-acrylic. Preferred are α-olefin homopolymers or copolymers such as ethyl acid copolymer, ethylene-methyl acrylate copolymer, ethylene-acrylic acid copolymer, ionomer, or mixtures thereof, and other polyurethanes, styrene-ethylene. Listed are thermoplastic elastomers such as butene or pentene copolymers, polyamide-polyol copolymers, and mixtures thereof. Moreover, you may use what made these two or more layers.

  Furthermore, in order to improve the adhesiveness with the pressure-sensitive adhesive layer, the surface of the base film may be appropriately subjected to a treatment such as a corona treatment or a primer layer. The thickness of the base film is usually preferably 30 to 300 μm from the viewpoint of strong elongation characteristics and radiation transparency.

(Adhesive layer)
The dicing die bond sheet for laser dicing of the present invention has a pressure-sensitive adhesive layer formed on a base film, and the pressure-sensitive adhesive layer can be produced by appropriately forming a pressure-sensitive adhesive on a base film by a conventionally known method. For example, it can be manufactured by coating on a base film. In the present invention, when light is irradiated from the pressure-sensitive adhesive layer side, the diffuse reflectance at a wavelength of 355 nm is set to 10% or more. Any material having such characteristics can be used without particular limitation. For example, it can be achieved by laminating at least two pressure-sensitive adhesive layers. In that case, the material to be laminated may be the same material or different materials, which can be achieved by appropriate selection.
In addition, by adding an additive having bead particles or flakes to the pressure-sensitive adhesive layer, the diffuse reflectance at a wavelength of 355 nm can be 10% or more when light is irradiated from the pressure-sensitive adhesive layer side.
In the present invention, the diffuse reflectance at a wavelength of 355 nm when light is irradiated from the pressure-sensitive adhesive layer side, for example, is cut into a shape corresponding to a wafer to be bonded in advance to the pressure-sensitive adhesive layer (pre-cut). In the case of a dicing die-bonding sheet for laser dicing, where the adhesive film is laminated and the part to which the ring frame for dicing is bonded does not have an adhesive layer, the adhesive is the part without the adhesive layer. It is obtained by irradiating light from the layer side. That is, the diffuse reflectance at a wavelength of 355 nm when light is irradiated from the pressure-sensitive adhesive layer side is the diffuse reflectance when the pressure-sensitive adhesive layer without the adhesive layer is directly irradiated.

By adopting these methods to form the pressure-sensitive adhesive layer, it can be peeled off without any problem when the pressure-sensitive adhesive layer and the wafer fixing adhesive layer are peeled off after the workpiece has been cut. The reason is not clear, but when the workpiece is cut by irradiating the laser, the laser is scattered and reflected by the pressure-sensitive adhesive layer, and the influence on the pressure-sensitive adhesive layer is reduced. It seems that heat fusion can be reduced.
In this invention, it is preferable that the total light transmittance in wavelength 355nm of the adhesive layer which consists of laminated structures shall be 80% or more. In this invention, after a dicing process, it peels between an adhesive layer and the adhesive layer for wafer fixation.

As a material used for the pressure-sensitive adhesive layer of the present invention, various types of pressure-sensitive adhesives such as conventionally known acrylic, rubber-based, polyurethane-based, silicone-based, and polyester-based materials can be appropriately selected. Among these, an acrylic pressure-sensitive adhesive is particularly preferably used from the viewpoint of easy control of pressure-sensitive adhesive properties. The acrylic pressure-sensitive adhesive is a pressure-sensitive adhesive mainly composed of an acrylic copolymer. Acrylic copolymers usually have a (meth) acrylic acid ester monomer having an alkyl group having 1 to 18 carbon atoms as a main monomer, a monomer having a functional group such as a hydroxyl group, a carboxyl group or an amino group, or other copolymer. It is obtained by copolymerizing polymerizable monomers.
The thickness of the pressure-sensitive adhesive layer is preferably 5 to 30 μm.

(Wafer fixing adhesive layer)
In the dicing die bond sheet for laser dicing of the present invention, an adhesive layer is laminated on an adhesive layer. Hereinafter, the wafer fixing adhesive layer is also simply referred to as an adhesive layer.
Here, the adhesive layer is attached to the chip when the chip is picked up after the semiconductor wafer or the like is bonded and diced, and is used as an adhesive for fixing the chip to the substrate or lead frame. It is what is done. For the adhesive layer, a film-like adhesive generally used for dicing die-bonding sheets can be used, such as an acrylic adhesive, an epoxy resin / phenolic resin / acrylic resin blend adhesive, and the like. It can be preferably used. The thickness may be appropriately set, but is preferably about 5 to 100 μm.
The resin composition constituting the adhesive layer has such adhesiveness that it can be bonded to a wafer at normal temperature and can be diced, and can be peeled off from the adhesive layer after the dicing is completed, and then the adhesive property is obtained by heating. It expresses and acts as a die bond agent. The heating at this time is not particularly limited, but is preferably performed at 40 to 100 ° C, more preferably at 60 to 80 ° C.
If it is an adhesive which can exhibit such performance, it can be used as the adhesive layer which is the outermost layer without any particular limitation. It is preferable to contain an epoxy group-containing copolymer having a radiation curable carbon-carbon double bond together with the epoxy resin. Examples of the epoxy group-containing copolymer having a radiation curable carbon-carbon double bond include glycidyl acrylate or glycidyl methacrylate having a radiation curable carbon-carbon double bond.

  In addition to the epoxy group-containing acrylic copolymer (a) having a carbon-carbon double bond and the epoxy resin (b), the adhesive layer may further comprise a phenol resin (c). Each component will be described below.

  Regarding the epoxy group-containing acrylic copolymer (a) having a carbon-carbon double bond, for example, a monomer having a radiation curable carbon-carbon double bond such as an alkyl acrylate or alkyl methacrylate (( 1) -1) and a compound (1) obtained by copolymerizing a monomer having an epoxy group as a functional group ((1) -2), a carboxyl group, a cyclic acid anhydride, and an amino group It can be obtained by reaction with compound (2). Further, the Tg of the epoxy group-containing acrylic copolymer (a) having a carbon-carbon double bond is preferably −50 ° C. or more and 0 ° C. or less in order to provide tack at normal temperature.

  The epoxy resin (b) used in the present invention is not particularly limited as long as it is cured and exhibits an adhesive action, but is an epoxy having two or more functional groups, preferably having a molecular weight of less than 5000, more preferably less than 3000. Resin can be used. Further, an epoxy resin having a molecular weight of preferably 500 or more, more preferably 800 or more can be used.

  Examples of such epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, alicyclic epoxy resins, aliphatic chain epoxy resins, phenol novolac type epoxy resins, and cresol novolac types. Epoxy resin, bisphenol A novolak type epoxy resin, diglycidyl etherified product of biphenol, diglycidyl etherified product of naphthalenediol, diglycidyl etherified product of phenol, diglycidyl etherified product of alcohol, and alkyl substitution products thereof , Bifunctional epoxy resins such as halides and hydrogenated products, and novolac type epoxy resins. Moreover, what is generally known, such as a polyfunctional epoxy resin and a heterocyclic ring-containing epoxy resin, can also be applied. These can be used alone or in combination of two or more. Furthermore, components other than the epoxy resin may be included as impurities within a range that does not impair the characteristics.

  More specifically, for example, commercially available products include Epicoat 807, Epicoat 815, Epicoat 825, Epicoat 827, Epicoat 828, Epicoat 834, Epicoat 1001, Epicoat 1002, Epicoat 1003, Epicoat 1055, Epicoat 1004, Epicoat 1004AF, and Epicoat 1007. , Epicoat 1009, Epicoat 1003F, Epicoat 1004F (trade name, manufactured by Japan Epoxy Resin Co., Ltd.), DER-330, DER-301, DER-361, DER-661, DER-662, DER-663U, DER-664 , DER-664U, DER-667, DER-642U, DER-672U, DER-673MF, DER-668, DER-669 (above, manufactured by Dow Chemical Co., Ltd. Name), YD8125, YDF8170 (above, manufactured by Toto Kasei Co., Ltd., trade name) and other bisphenol A type epoxy resins, YDF-2004 (manufactured by Toto Kasei Co., Ltd., trade name) and other bisphenol F type epoxy resins, Epicoat 152, Phenol novolac epoxy resins such as Epicoat 154 (trade name, manufactured by Japan Epoxy Resin Co., Ltd.), EPPN-201 (trade name, manufactured by Nippon Kayaku Co., Ltd.), DEN-438 (trade name, manufactured by Dow Chemical Company) , Epicoat 180S65 (trade name, manufactured by Japan Epoxy Resin Co., Ltd.), Araldite ECN1273, Araldite ECN1280, Araldite ECN1299 (above, product name manufactured by Ciba Specialty Chemicals), YDCN-701, YDCN-702, YDCN-703, Y CN-704 (above, manufactured by Toto Kasei Co., Ltd., trade name), EOCN-102S, EOCN-103S, EOCN-104S, EOCN-1012, EOCN-1020, EOCN-1025, EOCN-1027 (above, Nippon Kayaku Co., Ltd.) Cresol novolac type epoxy resin such as ESCN-195X, ESCN-200L, ESCN-220 (above, trade name made by Sumitomo Chemical Co., Ltd.), Epon 1031S, Epicoat 1032H60, Epicoat 157S70 (above, Japan Epoxy Resin Co., Ltd., trade name), Araldite 0163 (Ciba Specialty Chemicals, trade name), Denacol EX-611, Denacol EX-614, Denacol EX-622B, Denacol EX-622, Denacol EX-51 2, Denacol EX-521, Denacol EX-421, Denacol EX-411, Denacol EX-321 (above, Nagase Kasei Co., Ltd., trade name), EPPN501H, EPPN502H (above, Nippon Kayaku Co., Ltd., trade name) Multifunctional epoxy resin such as Epicoat 604 (trade name, manufactured by Japan Epoxy Resin Co., Ltd.), YH-434 (trade name, manufactured by Toto Kasei Co., Ltd.), TETRAD-X, TETRAD-C (above, Mitsubishi Gas Chemical Co., Ltd.) Product name), amine type epoxy resin such as ELM-120 (manufactured by Sumitomo Chemical Co., Ltd., trade name), hetero ring-containing epoxy resin such as Araldite PT810 (trade name, manufactured by Ciba Specialty Chemicals), ERL4234, ERL4299 , ERL4221, ERL4206 (above, manufactured by UCC, product ) Etc. can be used cycloaliphatic epoxy resins such as these can be used alone or in combinations of two or more.

  In the present invention, from the viewpoint of heat resistance, it is preferable to use an epoxy resin that is solid at room temperature and has a softening point of 50 ° C. or higher measured by a ring and ball type. ) It is preferably 20% by weight or more, more preferably 40% by weight or more, and still more preferably 60% by weight or more. For example, in a commercial item, YDCN-703, YDCN-704 (above, Toto Kasei Co., Ltd., trade name), Epicoat 1004, Epicoat 1007 (above, Japan Epoxy Resin Co., Ltd., trade name), etc. Can do.

  An epoxy resin having a molecular weight of 600 or more and a softening point of 50 ° C. or more has such a large difference in polarity from the epoxy group-containing acrylic copolymer (a) that it is difficult to be compatible. It is preferable to do.

  In the present invention, the epoxy equivalent of the epoxy resin (b) is preferably 100 to 2000 g / eq, more preferably 150 to 1000 g / eq, and further preferably 150 to 300 g / eq. . When the epoxy equivalent is less than 100 g / eq, the cured product tends to be brittle and the adhesiveness tends to decrease, and when it exceeds 2000 g / eq, the Tg tends to decrease and the heat resistance tends to deteriorate.

  The phenol resin (c) is not particularly limited as long as it acts as a curing agent for the epoxy resin. However, it is preferable to use a novolak-type or resol-type resin because it has excellent resistance to electric corrosion during moisture absorption. The hydroxyl equivalent is preferably 150 to 400 g / eq, more preferably 180 to 300 g / eq, and still more preferably 180 to 250 g / eq. When the hydroxyl group equivalent is less than 150 g / eq, the water absorption increases and the reflow resistance tends to deteriorate, and when it exceeds 400 g / eq, the Tg tends to decrease and the heat resistance tends to deteriorate.

  Specific examples of such a phenol resin include a phenol resin represented by the following general formula (I).

(In the formula, R 1 s may be the same or different and each represents a hydrogen atom, a linear or branched alkyl group having 1 to 10 carbon atoms, a cyclic alkyl group, an aralkyl group, an alkenyl group, a hydroxyl group, an aryl group, or a halogen atom. Represents an atom, n represents an integer of 1 to 3, and m represents an integer of 0 to 50)

  From the viewpoint of moisture resistance, the phenol resin (c) preferably has a water absorption rate of 2% by weight or less after being placed in a constant temperature and humidity chamber at 85 ° C. and 85% RH for 48 hours. In addition, the heating weight reduction rate at 350 ° C. (temperature increase rate: 5 ° C./min, atmosphere: nitrogen) measured with a thermogravimetric analyzer (TGA) is less than 5% by weight. Suppressing volatile matter, etc., increase the reliability of various properties such as heat resistance and moisture resistance, and reduce contamination of equipment due to volatile matter during work such as heat processing ,preferable.

  The phenol resin of the present invention represented by the formula (I) can be obtained, for example, by reacting a phenol compound and a xylylene compound which is a divalent linking group in the presence of no catalyst or an acid catalyst. Moreover, as a commercial item, the Millex XLC-series, the XL series (above, Mitsui Chemicals make, brand name) etc. can be mentioned, for example.

  The blending amount of the phenol resin (c) and the epoxy resin (b) is preferably 0.70 / 0.30 to 0.30 / 0.70 in terms of equivalent ratio of epoxy equivalent and hydroxyl equivalent, respectively. .65 / 0.35 to 0.35 / 0.65 is more preferable, 0.60 / 0.30 to 0.30 / 0.60 is further preferable, and 0.55 / 0.45. It is particularly preferable to be -0.45 / 0.55. When the blending ratio exceeds the above range, the curability may be inferior when an adhesive is used.

  Examples of the phenol compound used for the production of the phenol resin of the formula (I) include phenol, o-cresol, m-cresol, p-cresol, o-ethylphenol, p-ethylphenol, o-n-propylphenol, m- n-propylphenol, pn-propylphenol, o-isopropylphenol, m-isopropylphenol, p-isopropylphenol, on-butylphenol, mn-butylphenol, pn-butylphenol, o-isobutylphenol, m-isobutylphenol, p-isobutylphenol, octylphenol, nonylphenol, 2,4-xylenol, 2,6-xylenol, 3,5-xylenol, 2,4,6-trimethylphenol, resorcin, catechol, hydro Non, 4-methoxyphenol, o-phenylphenol, m-phenylphenol, p-phenylphenol, p-cyclohexylphenol, o-allylphenol, p-allylphenol, o-benzylphenol, p-benzylphenol, o-chloro Examples include phenol, p-chlorophenol, o-bromophenol, p-bromophenol, o-iodophenol, p-iodophenol, o-fluorophenol, m-fluorophenol, p-fluorophenol and the like.

  These phenol compounds may be used alone or in combination of two or more. Particularly preferred are phenol, o-cresol, m-cresol, p-cresol and the like.

  As the xylylene compound which is a divalent linking group used for the production of the phenol resin of the formula (I), the following xylylene dihalide, xylylene glycol and derivatives thereof can be used. That is, α, α′-dichloro-p-xylene, α, α′-dichloro-m-xylene, α, α′-dichloro-o-xylene, α, α′-dibromo-p-xylene, α, α ′ -Dibromo-m-xylene, α, α'-dibromo-o-xylene, α, α'-diiodo-p-xylene, α, α'-diiodo-m-xylene, α, α'-diiodo-o-xylene , Α, α′-dihydroxy-p-xylene, α, α′-dihydroxy-m-xylene, α, α′-dihydroxy-o-xylene, α, α′-dimethoxy-p-xylene, α, α′- Dimethoxy-m-xylene, α, α′-dimethoxy-o-xylene, α, α′-diethoxy-p-xylene, α, α′-diethoxy-m-xylene, α, α′-diethoxy-o-xylene, α, α′-di-n-propoxy-p-xylene, α, α′-n-propoxy-m- Xylene, α, α'-di-n-propoxy-o-xylene, α, α'-di-isopropoxy-p-xylene, α, α'-diisopropoxy-m-xylene, α, α'-di Isopropoxy-o-xylene, α, α'-di-n-butoxy-p-xylene, α, α'-di-n-butoxy-m-xylene, α, α'-di-n-butoxy-o- Xylene, α, α′-diisobutoxy-p-xylene, α, α′-diisobutoxy-m-xylene, α, α′-diisobutoxy-o-xylene, α, α′-di-tert-butoxy-p-xylene, α, α′-di-tert-butoxy-m-xylene, α, α′-di-tert-butoxy-o-xylene can be mentioned, among which α, α′-dichloro-p-xylene, α, α'-dichloro-m-xylene, α, α'-dichloro-o-xylene α, α′-dihydroxy-p-xylene, α, α′-dihydroxy-m-xylene, α, α′-dihydroxy-o-xylene, α, α′-dimethoxy-p-xylene, α, α′-dimethoxy -M-xylene and α, α'-dimethoxy-o-xylene, which can be used alone or in combination of two or more.

  When the above phenol compound and xylylene compound are reacted, mineral acids such as hydrochloric acid, sulfuric acid, phosphoric acid and polyphosphoric acid; organic compounds such as dimethyl sulfuric acid, diethyl sulfuric acid, p-toluenesulfonic acid, methanesulfonic acid and ethanesulfonic acid Carboxylic acids; Super strong acids such as trifluoromethane sulfonic acid; Strong acidic ion exchange resins such as alkane sulfonic acid type ion exchange resin; Super strong acidic ion exchange such as perfluoroalkane sulfonic acid type ion exchange resin Resins (trade name: Nafion, Nafion, manufactured by Du Pont); natural and synthetic zeolites; activated clay (acid clay), etc., and an xylylene compound that is substantially a raw material at 50 to 250 ° C. The reaction is continued until it disappears and the reaction composition becomes constant. Although the reaction time depends on the raw materials and the reaction temperature, it is generally about 1 to 15 hours. In practice, it may be determined while tracking the reaction composition by GPC (gel permeation chromatography) or the like.

  In exceptional cases, when a halogenoxylene derivative such as α, α′-dichloro-p-xylene is used, an acid catalyst is necessary because the reaction proceeds without a catalyst while generating a corresponding hydrogen halide gas. And not. In other cases, the reaction proceeds in the presence of an acid catalyst to produce the corresponding water or alcohol.

  In addition, the reaction molar ratio of a phenolic compound and a xylylene compound usually uses a phenolic compound excessively, and collect | recovers an unreacted phenolic compound after reaction. At this time, the average molecular weight is determined by the amount of the phenol compound, and the phenol compound having a lower average molecular weight can be obtained as the phenol compound is more excessive. In addition, the phenol resin whose phenol compound part is allylphenol is obtained by, for example, producing a non-allylated phenol resin, reacting it with allyl halide, allyl ether, and then allylating by Claisen transition. Can do.

  In the present invention, a filler (d) and a curing accelerator (e) can also be added. Specific examples of the filler (d) include inorganic fillers and organic fillers, and inorganic fillers are added to improve handling properties, improve thermal conductivity, adjust melt viscosity and impart thixotropic properties. It is preferable.

There are no particular restrictions on the inorganic filler. For example, aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum oxide, aluminum nitride, aluminum borate whisker, nitriding Examples thereof include boron, crystalline silica, and amorphous silica. These may be used alone or in combination of two or more. In order to improve thermal conductivity, aluminum oxide, aluminum nitride, boron nitride, crystalline silica, amorphous silica and the like are preferable. Silica is preferable from the viewpoint of balance of properties.
In the present invention, the energy of the laser beam irradiated at the time of laser dicing is absorbed by the adhesive layer and transmitted to the vicinity of the thermoplastic film interface of the adhesive layer, and the adhesive layer is cut in accordance with the element piece. is required. In order to do so, it is preferable to be able to adjust by said filler content, and it is preferable that the content shall be 5-40 mass% by weight%.
The light transmittance at 355 nm of the adhesive layer is preferably 80% or less.

  The average particle diameter of (d) of the filler is preferably 0.005 to 0.1 μm, more preferably 0.008 to 0.05 μm, and further preferably 0.01 to 0.03 μm. preferable. When the average particle size of the filler is less than 0.005 μm, the wettability to the adherend tends to decrease and the adhesion tends to decrease. When the average particle size exceeds 0.1 μm, the reinforcing effect due to the addition of the filler decreases, and the heat resistance Tends to decrease. In addition, in this invention, an average particle diameter means the average value calculated | required from the particle size of 100 fillers measured by TEM, SEM, etc.

  As a specific example of the filler, silica is a product name of Nanotech SiO2 (contact angle: 43 degrees, average particle size: 0.012 μm) from CI Chemical Co., Ltd., or Aerosil R972 (average particle size: from Nippon Aerosil Co., Ltd.). 0.016 μm). Alumina is commercially available from CI Kasei Co., Ltd. under the trade name Nanotech Al2O3 (contact angle: 55 degrees, average particle size: 0.033 μm). Antimony trioxide is commercially available from Nippon Seiko Co., Ltd. under the trade name PATOX-U (contact angle: 43 degrees, average particle size: 0.02 μm).

  There is no restriction | limiting in particular as hardening accelerator (e) used for the adhesive agent of this invention, For example, a tertiary amine, imidazoles, a quaternary ammonium salt etc. can be used. Examples of imidazoles preferably used in the present invention include 2-methylimidazole, 2-ethyl-4-methylimidazole, 1-cyanoethyl-2-phenylimidazole, 1-cyanoethyl-2-phenylimidazolium trimellitate, and the like. These may be used alone or in combination of two or more. Imidazoles are commercially available, for example, from Shikoku Kasei Kogyo Co., Ltd. under the trade names 2E4MZ, 2PZ-CN, and 2PZ-CNS.

  The blending amount of the curing accelerator (e) is preferably 0.01 to 5% by weight, and 0.05 to 3% by weight with respect to the total amount of the epoxy resin (b) and the phenol resin (c). More preferably, it is more preferable to set it as 0.2 to 3 weight%. When the blending amount of the curing accelerator is less than 0.01% by weight, the epoxy resin is insufficiently cross-linked, and the heat resistance tends to decrease. When the amount exceeds 5% by weight, the storage stability decreases. There is a tendency for pot life to be insufficient.

  In addition, various coupling agents can be added to the adhesive composition of the present invention in order to improve interfacial bonding between different materials. Examples of the coupling agent include silane-based, titanium-based, and aluminum-based, and silane-based coupling agents are most preferable. The addition amount of the coupling agent is preferably 0 to 10 parts by weight with respect to 100 parts by weight of the total resin due to its effect, heat resistance and cost.

  In addition, when this adhesive layer is cured by ultraviolet irradiation and peeled off from the pressure-sensitive adhesive layer, a photopolymerization initiator such as isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler's ketone, chlorothioxanthone, dodecylthioxanthone is optionally used. , Dimethylthioxanthone, diethylthioxanthone, benzyldimethyl ketal, α-hydroxycyclohexyl phenyl ketone, 2-hydroxymethylphenylpropane, and the like can be used. When a pressure-sensitive adhesive using an acrylic copolymer is used for the adhesive layer, the amount of these photopolymerization initiators is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the acrylic copolymer. .

  In addition to the resin as described above, a resin used for the adhesive layer can be appropriately selected, and a polyimide resin or a silicone resin can be used.

In the dicing die-bonding sheet for laser dicing of the present invention, the adhesive layer is a film in which the adhesive layer is formed in advance (hereinafter referred to as an adhesive film), and the pressure-sensitive adhesive of the sheet in which the adhesive layer is formed on the base film. It may be formed by laminating on the surface of the agent layer. It is preferable to apply a linear pressure of 0.1 to 100 kgf / cm at a laminating temperature of 10 to 100 ° C. The adhesive film used on the separator may be peeled off after laminating, or used as a cover film for a dicing die bond sheet as it is and peeled off when a wafer is bonded. Also good.
The adhesive film may be laminated with an adhesive film that has been cut (pre-cut) into a shape corresponding to the wafer to be bonded in advance. When the adhesive film according to the wafer is laminated, when the dicing die bond sheet for laser dicing of the present invention is used, the portion to which the wafer is bonded has an adhesive layer and the dicing ring frame is bonded. The part does not have an adhesive layer and is used by being bonded to the pressure-sensitive adhesive layer. In general, since the adhesive layer is difficult to peel off from the adherend, adhesive residue is likely to occur on the ring frame or the like. By using the pre-cut adhesive film, the ring frame can be bonded to the pressure-sensitive adhesive layer, and the effect of hardly causing adhesive residue on the ring frame when the tape is peeled after use can be obtained.

Next, the present invention will be described in more detail based on examples.
(Preparation of release film with adhesive layer for wafer fixation)
YDCN-703 (trade name, manufactured by Toto Kasei Co., Ltd., cresol novolac type epoxy resin, epoxy equivalent 210, molecular weight 1200, softening point 80 ° C.) 55 parts by mass as an epoxy resin, and Mirex XLC-LL (Mitsui Chemicals, Inc.) as a phenol resin ) Product name, phenol resin represented by formula (I), hydroxyl group equivalent 175, water absorption 1.8%, heating weight reduction rate at 350 ° C. 4%) 45 parts by mass, NUC A-189 as silane coupling agent (Nippon Unicar Co., Ltd. trade name, γ-mercaptopropyltrimethoxysilane) 1.7 parts by mass and NUC A-1160 (Nippon Unicar Co., Ltd. trade name, γ-ureidopropyltriethoxysilane) 3.2 masses Part, Aerosil R972 as filler (silica surface coated with dimethyldichlorosilane, 400 ° C reactor A cyclohexanone was added to the composition consisting of 32 parts by mass of a filler having an organic group such as a methyl group hydrolyzed in the above, a product name manufactured by Nippon Aerosil Co., Ltd., silica, and an average particle size of 0.016 μm. They were mixed and further kneaded for 90 minutes using a bead mill.

  280 parts by weight of acrylic rubber HTR-860P-3 (trade name, mass average molecular weight of 800,000 manufactured by Nagase ChemteX Corporation) containing 3% by mass of glycidyl acrylate or glycidyl methacrylate, and Curazole 2PZ-CN as a curing accelerator (Shikoku Kasei Co., Ltd. product name, 1-cyanoethyl-2-phenylimidazole) 0.5 parts by mass was added, stirred and mixed, vacuum degassed to obtain a varnish.

  The varnish was applied onto a 35 μm thick release-treated film, heated and dried at 140 ° C. for 5 minutes to form a coating film, and the release layer with a wafer fixing adhesive layer having an adhesive layer thickness of 40 μm was formed. A film was prepared.

(Production of dicing die bond sheet for laser dicing)
Example 1
First, the compound (A0) having a radiation curable carbon-carbon double bond and a functional group is composed of 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate and methyl methacrylate, and has a mass average molecular weight of 700,000 and a glass transition temperature of -64 ° C. A copolymer compound having a radiation-curable carbon-carbon double bond content of 0.9 meq / g was prepared. 3 parts by mass of polyisocyanate compound coronate L (manufactured by Nippon Polyurethane Co., Ltd., trade name) is added as a curing agent to 100 parts by mass of this compound (A0), and Irgacure 184 (manufactured by Nippon Ciba Geigy Co., Ltd.) as a photopolymerization initiator. (Trade name) By adding 5 parts by mass, a radiation-curable pressure-sensitive adhesive composition (A1) was obtained.

Furthermore, an acrylic base polymer (B0) having a mass average molecular weight of 700,000, a glass transition temperature of −45 ° C., and a hydroxyl value of 17 is prepared, and polyisocyanate compound Coronate L (Japan) is used as a curing agent for 100 parts by mass of the base polymer. Polyurethane Co., Ltd., trade name) 10 parts by mass was added to obtain an acrylic pressure-sensitive adhesive composition (B1).
Next, as a base film, an ethylene-vinyl acetate copolymer film having a thickness of 100 μm was prepared, and the acrylic adhesive composition (B1) was dried on the film so that the thickness after drying was 10 μm. The pressure-sensitive adhesive layer 1 was formed. Separately from this, the radiation-curable pressure-sensitive adhesive composition (A1) is formed on a polyethylene terephthalate film which has been subjected to a release treatment so that the thickness after drying becomes 10 μm, and the pressure-sensitive adhesive surface of (A1) and (B1 ) Was adhered to obtain a sheet having (B1) as the pressure-sensitive adhesive layer 1 and then (A1) as the pressure-sensitive adhesive layer 2 on the base film. Further, a dicing die bond for laser dicing in which a release film with an adhesive layer having a thickness of 40 μm prepared in advance is bonded to the pressure-sensitive adhesive surface of (A1), and the release film is laminated. A sheet was obtained.

(Comparative Example 1)
As a base film, an ethylene-vinyl acetate copolymer film having a thickness of 100 μm is prepared, and an adhesive layer is formed on the film so that the thickness after drying (A1) is 10 μm. The sheet | seat in which the adhesive layer (A1) was formed in the material film was obtained. Further, similarly to the example, a release film with an adhesive layer prepared in advance was bonded to the pressure-sensitive adhesive surface to obtain a dicing die bond sheet for laser dicing.

(Evaluation)
The release film was peeled off from the dicing die bond sheet for laser dicing on which the release film was laminated, and the following items were evaluated. The results are shown in Table 1.

(Light transmittance and diffuse reflectance)
The light transmittance at 355 nm of the pressure-sensitive adhesive layer was measured at N = 5 by using a transmittance meter (manufactured by Shimadzu Corporation, trade name: UV3101PC & MPC-3100) for the total light transmittance at a wavelength of 355 nm with the pressure-sensitive adhesive layer alone. The average value was obtained. Similarly, the light transmittance at 355 nm of the wafer fixing adhesive layer was measured, and the average value was defined as the light transmittance at 355 nm. Moreover, the diffuse reflectance in 355 nm of the layer in which the adhesive layer 1 and the adhesive layer 2 were formed on the base film was determined by measuring the diffuse reflectance on the adhesive layer side (manufactured by Shimadzu Corporation, trade name: UV3101PC & MPC-3100). The average value was obtained by using N = 5.

(Success rate of pickup by laser dicing)
A dicing die bond sheet for laser dicing was heat bonded at 70 ° C. for 10 seconds on the backside of a 50 μm thick wafer, and then dicing was performed by two-stage irradiation using a laser dicing apparatus. The wafer was cut by the first irradiation, and the wafer fixing adhesive layer of the dicing die bond sheet for laser dicing was cut by the second irradiation.

For dicing, laser dicing was performed with a chip size of 7 × 7 mm by laser irradiation from the wafer surface side. Thereafter, a pick-up test using a die bonder device (trade name: CPS-100FM, manufactured by NEC Machinery) was performed on 50 chips in the center of the silicon wafer, and the success rate of pick-up in terms of the number of pick-up chips was determined. At that time, the pick-up success rate was calculated assuming that the pick-up succeeded when the chip was picked up without breaking and the adhesive layer peeled from the thermoplastic film was held on the element. The conditions at that time were as follows: pin arrangement: 4 pins (Φ250 μm), expanding amount: 3 mm, push-up speed 50 mm / sec.

In Example 1 with two adhesive layers, the success rate of pick-up was 100%, which was good, but in Comparative Example 1, it was not possible to pick up stably.

Claims (3)

A dicing die bond sheet for laser dicing, in which a pressure-sensitive adhesive layer and a wafer fixing adhesive layer are sequentially laminated on a base film, and 355 nm when light is irradiated from the pressure-sensitive adhesive layer toward the base film A dicing die-bonding sheet for laser dicing characterized by having a diffuse reflectance of 10% or more. The dicing die-bonding sheet for laser dicing according to claim 1, wherein the pressure-sensitive adhesive layer has a light transmittance at 355 nm of 80% or more. The dicing die-bonding sheet for laser dicing according to claim 1 or 2, wherein the adhesive layer has a light transmittance at 355 nm of 80% or less.