JP2013229563A - Adhesive tape for protecting semiconductor wafer surface - Google Patents

Abstract

Provided is an adhesive tape for protecting a semiconductor wafer surface that suppresses adhesive residue and surface contamination (seapage) on the wafer surface after processing a semiconductor wafer, more specifically, a back grinding process and a tape peeling process for a silicon wafer or the like. To do.
SOLUTION: A pressure-sensitive water-based emulsion pressure-sensitive adhesive layer is provided on at least one surface of a base film, the gel fraction of a dispersion polymer of the water-based emulsion-type pressure-sensitive adhesive is 80% or more, and at 25 ° C. The adhesive strength to the SUS280 polished surface at the time of peeling is 0.8 to 2.5 N / 25 mm, and the adhesive strength to the SUS280 polished surface at the time of heat peeling at 50 ° C. is to the SUS280 polished surface at the time of peeling at 25 ° C. A pressure-sensitive adhesive tape for protecting a semiconductor wafer surface, the average particle diameter of which is 50% or less with respect to the adhesive strength and the average particle size of the dispersed polymer in the adhesive is 0.13 to 0.18 μm.
[Selection] Figure 1

Description

  The present invention is an adhesive tape for protecting a surface of a semiconductor wafer used for processing a semiconductor wafer in manufacturing a semiconductor device such as a silicon wafer, and is used for fixing and backgrinding a semiconductor wafer or the like. The present invention relates to an adhesive tape for processing semiconductor wafers. More specifically, the present invention relates to a semiconductor wafer surface protective pressure-sensitive adhesive tape that can be peeled off from the tape bonding process through the back grinding process without any adhesive residue on the semiconductor wafer surface.

  The process of processing a semiconductor wafer or the like into a semiconductor chip and mounting it on an electronic device is, for example, a process of attaching a semiconductor wafer surface protective adhesive tape to the pattern surface of the semiconductor wafer, or grinding and thinning the back surface of the semiconductor wafer. A step of mounting the ground semiconductor wafer on the dicing tape, a step of peeling the adhesive tape for protecting the surface of the semiconductor wafer from the semiconductor wafer, a step of dividing the semiconductor wafer by dicing, a lead frame of the divided semiconductor chip After a die bonding process for bonding to a semiconductor chip, the semiconductor chip is configured by a molding process for sealing with a resin for external protection. The above-mentioned adhesive tape for protecting the surface of a semiconductor wafer is called a radiation curable type, and the adhesive strength is remarkably lowered after irradiation and is easily peeled off. There are roughly two types characterized by the same adhesive strength during processing and peeling. As this adhesive tape for protecting the surface of a semiconductor wafer, one in which an adhesive layer mainly composed of an acrylic polymer is provided on a polyolefin base resin film such as an ethylene-vinyl acetate copolymer has been proposed (for example, , See Patent Document 1).

  In the pattern on the surface of the semiconductor wafer, there are various electronic circuits and electrodes, a protective film such as polyimide for protecting them, and a scribe line which is a groove into which a blade cuts during a dicing process for dividing the semiconductor wafer into chips. Due to such a structure, the surface of the semiconductor wafer is not smooth and has steps and irregularities of several μm to several tens of μm.

  Although the level difference varies depending on the type of semiconductor wafer and device, it is expected that the semiconductor wafer surface protective pressure-sensitive adhesive tape is bonded to closely contact the level difference on the surface of the semiconductor wafer to fill the gap. However, when the step of the semiconductor wafer is large, or when the adhesive tape for protecting the surface of the semiconductor wafer is hard, followability to the surface of the semiconductor wafer is insufficient. As a result, a phenomenon called seapage occurs in which grinding water enters the gap between the semiconductor wafer and the adhesive tape for protecting the surface of the semiconductor wafer during the back grinding process.

  As a result of the generation of seapage, the adhesive tape for protecting the surface of the semiconductor wafer is peeled off from the semiconductor wafer, causing cracks in the semiconductor wafer from that location, leading to damage, contamination of the surface of the semiconductor wafer due to ingress water, Adhesion occurs and causes a significant deterioration in yield.

  For the generation of seapage, for example, as shown in Patent Document 2, there is known a method for improving the adhesion to the surface of a semiconductor wafer by increasing the thickness of the pressure-sensitive adhesive or decreasing the elastic modulus of the pressure-sensitive adhesive. . A similar effect can be expected by increasing the adhesive strength.

  However, in the method as described above, since the adhesive and the semiconductor wafer surface are strongly adhered, the adhesive is cohesive and broken when the adhesive tape for protecting the semiconductor wafer surface is peeled off, and a part of the adhesive remains on the semiconductor wafer surface. There is a problem that a phenomenon called adhesive residue is likely to occur. In the case where adhesive residue is generated, it may cause a problem in wire bonding or electrical connection in a later process.

  By the way, in recent years when thinning of semiconductor wafers has progressed, thin film grinding of 100 μm or less is common especially for semiconductor memory applications. The device wafer is thinned to a predetermined thickness by backside grinding, and then formed into chips in a dicing process. A plurality of chips are stacked, wire-connected between the substrate and the chip, and then sealed with a resin to become a product. . Conventionally, a paste-like resin has been applied to the back side of a semiconductor wafer as an adhesive. However, in order to reduce the thickness and size of semiconductor chips and simplify the process, adhesive and adhesive ( A process in which a dicing die bond sheet on which a bonding sheet for die bonding) is laminated is bonded to the back surface (grind surface) of a semiconductor wafer and cut together with the semiconductor wafer in a dicing process has become common (for example, Patent Documents). 3). In this method, the adhesive with a uniform thickness is cut to the same size as the semiconductor chip, so there is no need for a process such as adhesive application, and the same equipment as a conventional dicing tape can be used. Is good.

  When the sheet is bonded, the semiconductor wafer surface protective adhesive tape is peeled off after the sheet is bonded. The Although heating is required at the time of bonding in order to make this sheet adhere to a semiconductor wafer, in recent years, heating at a higher temperature (up to 80 ° C.) may be required. When the elastic modulus of the pressure-sensitive adhesive is controlled by the addition amount of the cross-linking agent to reduce the elastic modulus, the adhesive is heated in a state where the cohesive force is insufficient and further adheres to the irregularities on the surface of the semiconductor wafer. In this case, the risk of adhesive residue is further increased.

  In order to cope with the above problem, there is a method in which a radiation curable pressure-sensitive adhesive is used, and at the time of peeling, the adhesive strength is reduced by radiation curing and the adhesive strength is reduced by increasing the cohesive force. However, since the adhesive causes curing shrinkage during radiation curing, stress is applied to the thinned semiconductor wafer, leading to a decrease in chip bending strength (strength of the chipped Si chip alone) when it is chipped after dicing. It can be connected.

JP 2000-8010 A JP 2002-53819 A JP 2007-53325 A

  The present invention solves the above-mentioned problems, and after processing a semiconductor wafer, more specifically, a back grinding process and a tape peeling process for a silicon wafer or the like, adhesive residue and surface contamination on the semiconductor wafer surface (mainly due to seapage) It is an object of the present invention to provide a semiconductor wafer surface protecting adhesive tape capable of grinding a semiconductor wafer thin film, characterized by being capable of suppressing the above.

  As a result of earnestly examining the above problems, the present inventor has applied the adhesive tape for protecting a semiconductor wafer surface having a pressure-sensitive adhesive layer in which an aqueous emulsion having a gel fraction in a specific range is applied as a main polymer of the adhesive. In the semiconductor wafer surface observation and XPS measurement after the back surface grinding and peeling of the adhesive tape for protecting the semiconductor wafer surface, it has been found that, particularly in the case of thin film grinding, adhesive residue and surface contamination due to cohesive failure of the adhesive can be significantly reduced. The present invention has been made based on this finding.

That is, the present invention
(1) It has a pressure-sensitive aqueous emulsion-type pressure-sensitive adhesive layer on at least one surface on a base film composed of a resin, and the gel fraction of the dispersion polymer of the aqueous emulsion-type pressure-sensitive adhesive is 80% or more, And the adhesive force to the SUS280 polished surface at the time of peeling at 25 ° C. is 0.8 to 2.5 N / 25 mm, and the adhesive force to the SUS280 polished surface at the time of heat peeling at 50 ° C. is A pressure-sensitive adhesive tape for protecting a semiconductor wafer surface, characterized in that the average particle size of the dispersed polymer in the pressure-sensitive adhesive is from 0.13 to 0.18 μm with respect to the adhesive strength to a SUS280 polished surface;
(2) The pressure-sensitive aqueous emulsion-type pressure-sensitive adhesive layer does not contain a cross-linking agent, The semiconductor wafer surface protecting pressure-sensitive adhesive tape according to (1),
(3) The dispersion polymer is composed of only atoms selected from carbon atoms, hydrogen atoms, oxygen atoms, nitrogen atoms, sulfur atoms and alkali metal atoms. The semiconductor wafer surface protecting adhesive tape as described,
(4) Any one of (1) to (3), wherein the main component of the polymer contained in the aqueous emulsion-type pressure-sensitive adhesive of the pressure-sensitive adhesive layer is a (meth) acrylic copolymer. Adhesive tape for semiconductor wafer surface protection as described in
(5) The semiconductor wafer surface protecting device according to any one of (1) to (4), wherein the dispersion polymer has at least methyl acrylate, butyl acrylate and 2-ethylhexyl acrylate as monomer components. Adhesive tape, and
(6) In any one of (1) to (5), the pressure-sensitive adhesive layer contains at least two kinds of compounds selected from a polypropylene glycol compound and a polyoxyalkylene alkylphenyl ether. The semiconductor wafer surface protecting pressure-sensitive adhesive tape described is provided.

In addition, in this invention, (meth) acryl is used by the meaning containing both acryl and methacryl, Comprising: These are also included.
Moreover, that a crosslinking agent is not contained means that the crosslinking agent is not added to the adhesive of an adhesive layer.

  The adhesive tape for protecting the surface of a semiconductor wafer according to the present invention is used for processing a semiconductor wafer, more specifically, in a back grinding process for a silicon wafer or the like, and for BG tape laminating, semiconductor wafer back grinding, and tape residue on the semiconductor wafer surface. And thin film grinding while suppressing surface contamination (seapage).

It is sectional drawing which shows the state by which the adhesive tape for semiconductor wafer surface protection of this invention was bonded by the semiconductor wafer pattern surface about preferable one Embodiment of this invention. It is explanatory drawing of the measuring method of the adhesive force of the adhesive tape for semiconductor wafer surface protections of this invention.

A preferred embodiment of the present invention will be described with reference to the cross-sectional view of FIG.
In the figure, 1 is a base film, and 2 is an adhesive layer applied thereon. Typically, a semiconductor wafer surface protecting adhesive tape is formed in such a configuration. 3 shows the wafer pattern surface (wiring layer) of the wafer Si layer 4 to which the adhesive layer 2 adheres.

In the present invention, the pressure-sensitive adhesive used in the pressure-sensitive adhesive layer is an aqueous emulsion type pressure-sensitive adhesive.
The aqueous emulsion-type pressure-sensitive adhesive includes an aqueous dispersion of polymer or a latex polymer (hereinafter collectively referred to as a dispersion polymer).

  In the present invention, any dispersion polymer may be used, but a dispersion polymer composed only of atoms selected from a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, a sulfur atom and an alkali metal atom is preferable. Here, the alkali metal atom forms a salt in a group having a low pKa, such as an acidic group, and more specifically, an alkali metal atom is incorporated as a salt-formed carboxyl group or a salt-formed sulfo group. And includes sodium and potassium.

  Examples of the monomer constituting the polymer composed only of atoms selected from a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, a sulfur atom and an alkali metal atom include (meth) acrylic acid alkyl or aryl esters, (meta ) Acrylic acid or alkali metal salts thereof, (meth) acrylamide, other monomers having an ethylenically unsaturated group (for example, itaconic acid, mesaconic acid, citraconic acid, fumaric acid, maleic acid or alkali metal salts thereof) Can be mentioned.

The dispersion polymer of the aqueous emulsion-type pressure-sensitive adhesive may contain a plurality of polymers, but the main component of the polymer to be contained is preferably a (meth) acrylic copolymer, and is a (meth) acrylic copolymer. As a result, the adhesive force can be easily controlled, and the gel fraction and the like can be controlled, so that contamination due to adhesive residue and organic matter can be reduced.
Here, the main component of the polymer to be contained means that it exceeds 50% by mass of the total solid content of all polymers contained in the aqueous emulsion-type pressure-sensitive adhesive, and preferably 60% by mass or more, More preferably, it is 80 mass% or more.
These dispersion polymers can be synthesized by, for example, ordinary emulsion polymerization. It can also be obtained by making the hydrophobic polymer into fine particles and dispersing in water with a surfactant. Emulsion polymerization is carried out in an aqueous solution in the presence of a surfactant (emulsifier).
As the (meth) acrylic copolymer, for example, as described in JP-A No. 2003-82307, a monomer mixture mainly composed of (meth) acrylic acid alkyl ester and a radically polymerizable functional group containing ethylene or propylene A (meth) acryl emulsion polymer obtained by emulsion polymerization (emulsion polymerization) using a nonionic anionic reactive emulsifier having an average oxide addition mole number of 15 or less and a redox polymerization initiator may be the main component.

The content of the dispersion polymer in the aqueous emulsion-type pressure-sensitive adhesive (in the coating liquid for forming the aqueous emulsion-type pressure-sensitive adhesive layer) (the solid content mass of the dispersion polymer in the total mass of the pressure-sensitive adhesive) is preferably 30 to 80. Although it is mass%, More preferably, it is 40-60 mass%, However It is not restrict | limited to this. If the amount of the dispersed polymer is too small, moisture may remain in the pressure-sensitive adhesive drying process. If the amount is too large, particles that are not fused in the drying process exist, and a non-filmed portion remains partially. Since the ratio of the film portion decreases, the risk of adhesive residue may increase.
By setting the content of the dispersed polymer in the above range, it is possible to eliminate the adhesive residue on the surface of the semiconductor wafer and suppress the generation of seapage, thereby determining the content.

Moreover, the average particle diameter of the dispersion polymer of an emulsion is 0.13-0.18 micrometer, Preferably it is 0.14-0.16 micrometer. This average particle diameter is 50 particles [Atomic force microscope (AFM)] [1 μm ² of the pressure-sensitive adhesive surface of the semiconductor wafer surface protecting adhesive tape cut to A4 size (sampling at a few points in the A4 sample) Mean particle diameter as a result of measurement for [confirmed with AFM shape image]. If the average particle size is too small, it tends to drop off from the pressure-sensitive adhesive surface after drying and easily leave glue, and if it is too large, the adhesion to the semiconductor wafer surface irregularities will decrease and induce sea page. May be a problem. It is preferable that the average particle diameter of the dispersed polymer is in the above range in order to achieve the object effect of the invention.

The (meth) acrylic copolymer (acrylic emulsion polymer) which is a dispersion polymer is preferably composed of (meth) acrylic acid alkyl ester and (meth) acrylic acid or an alkali metal salt thereof. Those composed of acid alkyl esters are more preferred. Further, the (meth) acrylic acid alkyl ester is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 80% by mass or more, based on the monomer constituting the dispersion polymer. It is especially preferable that it is -100 mass%.
Here, as for carbon number of the alkyl part of (meth) acrylic-acid alkylester, 1-12 are preferable, and it may be unsubstituted or may be substituted by the substituent.
The substituent may be any substituent, but is preferably a hydroxyl group or an epoxy group.

  Specific examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, ( Examples include isoamyl acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, and isodecyl (meth) acrylate. These may be used alone as described above, or may be used in combination of two or more. Among these, it is preferable to use a mixture of two or more types, and by mixing two or more types, various functions as an adhesive can be exhibited. It is more preferable to mix three or more kinds, including at least three kinds of methyl (meth) acrylate (methyl acrylate), butyl acrylate (butyl acrylate), and (meth) acrylate 2-ethylhexyl (2-ethylhexyl acrylate). It is particularly preferred to copolymerize the monomers. By copolymerizing three or more types of monomers, it is possible to more satisfactorily balance the step following ability and the non-contamination property including the adhesive residue.

In the present invention, a monomer in which the alkyl part of (meth) acrylic acid alkyl ester is substituted with a hydroxyl group or an epoxy group is also preferable, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, Examples include glycidyl (meth) acrylate, and glycidyl (meth) acrylate is particularly preferable.
In the present invention, it is preferable to use a compound in which the alkyl part of the (meth) acrylic acid alkyl ester is substituted for the unsubstituted alkyl of (meth) acrylic acid, and particularly those obtained by copolymerizing four or more types of monomers. preferable.
In addition, those in which the alkyl part of the above (meth) acrylic acid alkyl ester has a substituent, (meth) acrylic acid or an alkali metal salt thereof, together with the following monomers other than the (meth) acrylic acid type, are dispersed polymer particles. Stabilization, improvement in adhesion of the pressure-sensitive adhesive layer to the substrate, improvement in initial adhesion to the adherend, and the like can be adjusted.

Examples of monomers other than (meth) acrylic acid-based monomers include carboxylic acids having ethylenically unsaturated groups such as maleic acid and crotonic acid, N, N-diethylacrylamide, N, N-diethylacrylamide, N-isopropylacrylamide, and acryloylmorpholine. (Meth) acrylamide, vinyl acetate, styrene and the like. These may be used singly or in combination of two or more.
These (meth) acrylic acid alkyl esters in which the alkyl part has a substituent, (meth) acrylic acid or an alkali metal salt thereof, and the above monomers are all of the monomer components constituting the (meth) acrylic copolymer. 0.1-10 mass% is preferable with respect to mass, and 0.5-5 mass% is more preferable.

Moreover, in order to adjust the gel fraction of the pressure-sensitive adhesive layer, a polyfunctional monomer component can be added and copolymerized when the (meth) acrylic copolymer is polymerized.
The gel fraction can also be adjusted by mixing a water dispersible crosslinking agent. As the water dispersible crosslinking agent, an epoxy crosslinking agent is mainly used.
In the present invention, it is preferable not to use such a crosslinking agent. When such a crosslinking agent (including a water-dispersible crosslinking agent) is used, contamination due to the remaining crosslinking agent occurs.
30 mass% or less is preferable with respect to the main monomer component, and, as for said polyfunctional monomer component, 5-25 mass% is preferable.

  Examples of the polyfunctional monomer include diethylene glycol diacrylate, diethylene glycol dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, tetraethylene glycol diacrylate, tetraethylene glycol dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, 1 , 6-hexanediol diacrylate, 1,6-hexanediol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate Jibi Rubenzen and the like.

  In the present invention, the gel fraction of the dispersion polymer of the aqueous emulsion-type pressure-sensitive adhesive is 80% or more, preferably 80 to 97%, more preferably 90 to 95%. If the gel fraction is too low, adhesive residue and surface contamination cannot be suppressed. Increasing the gel fraction as described above is preferable because it prevents a decrease in cross-linking density and as a result further prevents adhesive residue.

  A polymerization initiator and a surfactant (emulsifier) are added to the monomer mixture by a conventional method, and a (meth) acrylic polymer can be synthesized by a usual emulsion polymerization (emulsion polymerization method). The emulsion polymerization can be performed by any method such as general batch polymerization, continuous dropping polymerization, and divided dropping polymerization, and is not particularly limited.

Surfactants include anionic and polypropylene glycol compounds such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and polyoxyethylene alkyl Nonionic surfactants such as ether and polyoxyalkylene alkylphenyl ether (for example, polyoxyethylene alkylphenyl ether) can be used in combination.
The polyoxyalkylene alkyl phenyl ether is preferably a polyoxyalkylene alkyl phenyl ether to which an allyl group is added.
Among these surfactants, one or more kinds are used, but preferably two or more kinds of surfactants are used in combination.
In the present invention, it is particularly preferable to use a polypropylene glycol compound and polyoxyalkylene alkylphenyl ether in combination, whereby organic contamination on the semiconductor wafer can be reduced.

  The compounding quantity of surfactant is 0.5-10 mass parts with respect to 100 mass parts of all monomer mixtures, Preferably it is about 1-7 mass parts. When the blending amount of the surfactant exceeds 10 parts by mass, the cohesive force of the pressure-sensitive adhesive decreases and the amount of contamination on the adherend increases, and contamination due to bleeding of the surfactant on the surface of the pressure-sensitive adhesive layer is also caused. May happen. Moreover, when the compounding quantity of an emulsifier is less than 0.5 mass part, the stable emulsification may not be maintained.

  As polymerization initiators, 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis (N, N′-dimethyleneisobutylamidine) Other azo compounds such as potassium persulfate, persulfates such as ammonium persulfate, peroxide compounds such as benzoyl peroxide and t-butyl hydroperoxide, hydrogen peroxide solution and ascorbic acid, hydrogen peroxide solution And redox polymerization initiators such as ferrous chloride, persulfate and sodium bisulfite.

  The polymerization initiator is desirably used in the range of 0.01 to 1.0 part by mass per 100 parts by mass of the total monomer mixture.

  Examples of the material of the base film used in the present invention include those described in JP-A No. 2004-186429. As the base film, known materials can be used, such as polyethylene, polypropylene, ethylene-propylene copolymer, polybutene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid ester copolymer, ionomer, etc. And α-olefin homopolymers or copolymers, engineering plastics such as polyethylene terephthalate, polycarbonate, and polymethyl methacrylate, and thermoplastic elastomers such as polyurethane, styrene-ethylene-butene, and pentene copolymers. Alternatively, a mixture of two or more selected from these groups or a multilayered structure may be used. As for the thickness of a base film, 50-200 micrometers is preferable.

  In order to form the above-mentioned pressure-sensitive adhesive layer on the base film, at least one type of pressure-sensitive adhesive may be applied by any method to at least one side of the base film. As for the thickness of an adhesive layer, 10-300 micrometers is preferable. Moreover, you may provide intermediate | middle layers, such as a primer layer, as needed between a base film and an adhesive layer.

  Moreover, you may stick the synthetic resin film normally used as a separator on the adhesive layer side in order to protect an adhesive layer until it uses for practical use as needed.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to these Examples.

<Example 1>
A polyoxyethylene alkylphenyl ether compound and a polypropylene glycol compound to which an allyl group was added as a surfactant were added to deionized pure water, and ammonium persulfate was added as a polymerization initiator and stirred while heating. Next, 33 parts by weight of methyl methacrylate, 33 parts by weight of butyl acrylate, 32 parts by weight of 2-ethylhexyl acrylate, 2 parts by weight of glycidyl methacrylate are added dropwise to the stirring solution, and the stirring is continued to carry out the polymerization. A composition was obtained.
The pressure-sensitive adhesive composition was applied on a 25 μm PET (polyethylene terephthalate) separator, dried at 110 ° C. for 2 minutes, and laminated on a 165 μm thick ethylene-vinyl acetate copolymer (EVA) film, A pressure-sensitive adhesive layer having a thickness of 40 μm was laminated to prepare a pressure-sensitive adhesive tape for protecting a semiconductor wafer surface.

<Example 2>
A polyoxyethylene alkylphenyl ether compound and a polypropylene glycol compound to which an allyl group was added as a surfactant were added to deionized pure water, and ammonium persulfate was added as a polymerization initiator and stirred while heating. Next, 25 parts by weight of methyl methacrylate, 32 parts by weight of butyl acrylate, 41 parts by weight of 2-ethylhexyl acrylate, 2 parts by weight of glycidyl methacrylate are added dropwise to the stirring solution, and the stirring is continued to carry out the polymerization. A composition was obtained.
A pressure-sensitive adhesive composition is applied onto a 25 μm PET separator, dried at 130 ° C. for 2 minutes, and laminated on a 165 μm thick ethylene-vinyl acetate copolymer (EVA) film to obtain a film thickness of 40 μm. The pressure-sensitive adhesive layer was laminated to produce a semiconductor wafer surface protective pressure-sensitive adhesive tape.

<Example 3>
A polyoxyethylene alkylphenyl ether compound and a polypropylene glycol compound to which an allyl group was added as a surfactant were added to deionized pure water, and ammonium persulfate was added as a polymerization initiator and stirred while heating. Next, 20 parts by mass of methyl methacrylate, 37 parts by mass of butyl acrylate, 41 parts by mass of 2-ethylhexyl acrylate, 2 parts by mass of glycidyl methacrylate, are added dropwise to the stirring solution, and the polymerization is continued while stirring to prepare an acrylic emulsion adhesive. A composition was obtained.
A pressure-sensitive adhesive composition is applied onto a 25 μm PET separator, dried at 130 ° C. for 2 minutes, and laminated on a 165 μm thick ethylene-vinyl acetate copolymer (EVA) film to obtain a film thickness of 40 μm. The pressure-sensitive adhesive layer was laminated to produce a semiconductor wafer surface protective pressure-sensitive adhesive tape.

<Example 4>
A polyoxyethylene alkylphenyl ether compound and a polypropylene glycol compound to which an allyl group was added as a surfactant were added to deionized pure water, and ammonium persulfate was added as a polymerization initiator and stirred while heating. Next, 22 parts by mass of methyl methacrylate, 35 parts by mass of butyl acrylate, 41 parts by mass of 2-ethylhexyl acrylate, 2 parts by mass of glycidyl methacrylate are added dropwise to the stirring solution, and the polymerization is continued while stirring to prepare an acrylic emulsion adhesive. A composition was obtained.
A pressure-sensitive adhesive composition is applied onto a 25 μm PET separator, dried at 130 ° C. for 2 minutes, and laminated on a 165 μm thick ethylene-vinyl acetate copolymer (EVA) film to obtain a film thickness of 40 μm. The pressure-sensitive adhesive layer was laminated to produce a semiconductor wafer surface protective pressure-sensitive adhesive tape.

<Example 5>
A polyoxyethylene alkylphenyl ether compound and a polypropylene glycol compound to which an allyl group was added as a surfactant were added to deionized pure water, and ammonium persulfate was added as a polymerization initiator and stirred while heating. Next, 35 parts by weight of methyl methacrylate, 22 parts by weight of butyl acrylate, 41 parts by weight of 2-ethylhexyl acrylate, 2 parts by weight of glycidyl methacrylate are added dropwise to the stirring solution, and the stirring is continued to carry out the polymerization. A composition was obtained.
A pressure-sensitive adhesive composition is applied onto a 25 μm PET separator, dried at 130 ° C. for 2 minutes, and laminated on a 165 μm thick ethylene-vinyl acetate copolymer (EVA) film to obtain a film thickness of 40 μm. The pressure-sensitive adhesive layer was laminated to produce a semiconductor wafer surface protective pressure-sensitive adhesive tape.

<Example 6>
A polyoxyethylene alkylphenyl ether compound and a polypropylene glycol compound to which an allyl group was added as a surfactant were added to deionized pure water, and ammonium persulfate was added as a polymerization initiator and stirred while heating. Next, 40 parts by mass of methyl methacrylate, 17 parts by mass of butyl acrylate, 41 parts by mass of 2-ethylhexyl acrylate, 2 parts by mass of glycidyl methacrylate, are added dropwise to the stirring solution, and further stirred and polymerized to obtain an acrylic emulsion adhesive. A composition was obtained.
A pressure-sensitive adhesive composition is applied onto a 25 μm PET separator, dried at 130 ° C. for 2 minutes, and laminated on a 165 μm thick ethylene-vinyl acetate copolymer (EVA) film to obtain a film thickness of 40 μm. The pressure-sensitive adhesive layer was laminated to produce a semiconductor wafer surface protective pressure-sensitive adhesive tape.

<Example 7>
A polyoxyethylene alkylphenyl ether compound and a polypropylene glycol compound to which an allyl group was added as a surfactant were added to deionized pure water, and ammonium persulfate was added as a polymerization initiator and stirred while heating. Next, 27 parts by mass of methyl methacrylate, 30 parts by mass of butyl acrylate, 41 parts by mass of 2-ethylhexyl acrylate, 2 parts by mass of glycidyl methacrylate, are added dropwise to the stirring solution, and the polymerization is continued while stirring to prepare an acrylic emulsion adhesive. A composition was obtained.
A pressure-sensitive adhesive composition is applied onto a 25 μm PET separator, dried at 130 ° C. for 2 minutes, and laminated on a 165 μm thick ethylene-vinyl acetate copolymer (EVA) film to obtain a film thickness of 40 μm. The pressure-sensitive adhesive layer was laminated to produce a semiconductor wafer surface protective pressure-sensitive adhesive tape.

<Comparative Example 1>
Polymerization was performed in 69 parts by mass of 2-ethylhexyl acrylate, 29 parts by mass of 2-hydroxyethyl acrylate, 2 parts by mass of methacrylic acid, and ethyl acetate to obtain an acrylic copolymer. 2.5 parts by weight of adduct isocyanate crosslinking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is blended into the polymerized acrylic copolymer, and adjusted with ethyl acetate to adjust the viscosity to be easy to apply, A pressure-sensitive adhesive composition was obtained.
A pressure-sensitive adhesive composition is applied on a 25 μm PET separator, dried, and laminated on a 165 μm-thick ethylene-vinyl acetate copolymer (EVA) film to form a pressure-sensitive adhesive layer having a thickness of 40 μm. The adhesive tape for surface protection of a semiconductor wafer was produced by laminating.

<Comparative example 2>
Polymerization was performed in 69 parts by mass of 2-ethylhexyl acrylate, 29 parts by mass of 2-hydroxyethyl acrylate, 2 parts by mass of methacrylic acid, and ethyl acetate to obtain an acrylic copolymer. 0.5 parts by mass of adduct isocyanate crosslinker coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) is blended into the polymerized acrylic copolymer, and adjusted with ethyl acetate to adjust the viscosity to be easy to apply, A pressure-sensitive adhesive composition was obtained.
A pressure-sensitive adhesive composition is applied on a 25 μm PET separator, dried, and laminated on a 165 μm-thick ethylene-vinyl acetate copolymer (EVA) film to form a pressure-sensitive adhesive layer having a thickness of 40 μm. The adhesive tape for surface protection of a semiconductor wafer was produced by laminating.

<Comparative Example 3>
ATR-340 (manufactured by Seiden Chemical Co., Ltd.), an acrylic copolymer, is blended with 1.0 part by mass of adduct isocyanate cross-linking agent Coronate L (trade name, manufactured by Nippon Polyurethane Co., Ltd.) to adjust the viscosity to be easy to apply. Therefore, the pressure-sensitive adhesive composition was obtained by adjusting with ethyl acetate.
A pressure-sensitive adhesive composition is applied onto a 25 μm PET separator, dried, and laminated by being laminated on an ethylene-vinyl acetate copolymer (EVA) film having a thickness of 100 μm to form a pressure-sensitive adhesive layer having a thickness of 30 μm. The adhesive tape for surface protection of a semiconductor wafer was produced by laminating.

[Characteristic evaluation test]
About the adhesive tape for semiconductor wafer processing of Examples 1-7 and Comparative Examples 1-3, the characteristic evaluation test was done as follows.

-Measurement of polymer gel fraction Two test pieces of 100 mm x 120 mm were cut out from the adhesive tapes for semiconductor wafer processing of Examples and Comparative Examples, and after separating the separator, the mass of the adhesive tape for semiconductor wafer processing of the test pieces was measured. An adhesive tape for processing a semiconductor wafer of a test piece was fixed with a pin with the adhesive side facing up in a polypropylene container having a diameter into which the test piece was placed. After putting 500 ml of toluene into the container so that the test piece was immersed in the solution, the sample was covered with a lid for 24 hours (in an environment of 25 ° C.) to prevent the solvent from volatilizing.
After 24 hours, the solvent in the container was discarded while being filtered with a metal mesh having a mesh diameter of # 150. Thereafter, the test piece was dried for 24 hours (in an environment of 25 ° C.) with the pressure-sensitive adhesive tape for processing semiconductor wafers placed in the container. After 24 hours, the mass was measured with an electronic balance. The value calculated by the following formula was used as the gel fraction of the polymer.
In addition, the mass of the base material was measured before tape formation, or the adhesive layer was peeled off with a solvent or the like after tape formation.

Polymer gel fraction [%]
= (Tape mass after solvent extraction-substrate mass) / (Tape mass before solvent extraction-substrate mass) x 100

・ Adhesive strength measurement test (a) Adhesive strength to SUS280 polished surface at 25 ° C. at the time of peeling Three samples of 25 mm wide × 300 mm long test pieces were collected from the adhesive tapes for semiconductor wafer processing of Examples and Comparative Examples, and separators were removed. After peeling, the SUS steel plate 6 having a thickness of 1.5 mm to 2.0 mm specified in JIS G 4305 finished with 280 of the water-resistant abrasive paper specified in JIS R 6253 for the test piece 5 by the method shown in FIG. A 2 kg rubber roller was pressure-bonded over 3 reciprocations on the top, and after standing for 1 hour, the adhesive strength was measured using a tensile tester 7 conforming to JIS B 7721 whose measured value was in the range of 15 to 85% of its capacity. In the figure, the arrow indicates the tensile direction. The measurement was performed at 25 ° C., and the 180-degree peeling method was used. The tensile speed at this time was 300 mm / min.
In Tables 1 and 2 below, the adhesive strength is shown as 25 ° C. adhesive strength.

(B) Adhesive strength to the polished surface of SUS280 at the time of heat peeling at 50 ° C. The adhesive strength was applied in the same manner as in the above method except that the SUS steel plate 6 was heated to 50 ° C. at a measurement temperature of 50 ° C. Measured, and this value was defined as the adhesive strength to the polished surface of SUS280 at the time of heat peeling at 50 ° C.
In Tables 1 and 2 below, it is shown as 50 ° C. adhesive strength.

(C) Ratio of adhesive strength to the SUS280 polished surface at 50 ° C. with respect to the adhesive strength to the SUS280 polished surface at the time of peeling at 25 ° C. The adhesive strength obtained as described above at 25 ° C. The ratio of the adhesive strength with respect to the SUS280 polished surface at the time of heat peeling at 50 ° C. with respect to the adhesive strength with respect to the SUS280 polished surface at the time of peeling was calculated.

Ratio of adhesive strength at 50 ° C. to adhesive strength at 25 ° C. =
(Adhesive strength at 50 ° C./Adhesive strength at 25 ° C.) × 100

・ Tape bonding The adhesiveness of the produced adhesive tape for processing semiconductor wafers is an automatic laminator (DR-3000II manufactured by Nitto Denko), which is bonded to an 8-inch (inch) PI film (film thickness 5.5 μm) Si wafer. A cut was made.

-Measurement of average particle diameter of emulsion particles The tape after applying and drying the adhesive was cut into A4 size, and several locations in the A4 sample were randomly sampled. It was set on an atomic force microscope (AFM) SPI4000 manufactured by Seiko Instruments Inc. (SII), and a shape image of a 1 μm ² region of the pressure-sensitive adhesive surface was measured by a dynamic force mode (DFM) using an Olympus standard product cantilever. The particle diameter of 50 particles in the image after measurement was measured, and the average value was defined as the average particle diameter.

-Adhesive residue evaluation The surface of the semiconductor wafer that was peeled in the peeling experiment was observed, and the presence or absence of adhesive residue was evaluated according to the following criteria.
No adhesive residue: ○
With adhesive residue: ×

・ Tape peelability With regard to tape peelability after semiconductor wafer backside grinding (80μm thick finish), using a full auto grinder DGP8760 + wafer mounter DFM2700 manufactured by DISCO, peeling is performed automatically, and a heat-fusing type peeling tape. -Using S-75C manufactured by Lintec Co., Ltd., heat-sealed at 170 ° C. for 2 seconds and peeled off. (Chuck table heating 50 ° C)
In the case where automatic peeling was possible, the mark was ◯, in the case where peeling was possible after several retries, the mark was △, and when peeling was impossible, the mark was ×.

・ Dust intrusion (seapage)
A laminator (trade name: DR-8500II, manufactured by Nitto Denko) is used on the groove-formed surface of an 8-inch diameter silicon wafer in which grooves having a width of 50 μm and a depth of 30 μm are formed at intervals of 5 mm over the entire surface. The semiconductor wafer surface protection tape was bonded. The semiconductor wafer to which the semiconductor wafer surface protection tape is bonded is ground to a thickness of 50μm with a grinder (trade name: DGP8760, manufactured by DISCO), and the penetration of cutting water into the grooves from the outer periphery of the semiconductor wafer after grinding is investigated. did.
The case where no intrusion occurred was marked with ◎, the case where almost no intrusion was observed was marked with ○, and the case where intrusion was seen was marked with ×.

・ Thin film grindability Back grinding was performed to a thickness of 50 μm in the same manner as the dust intrusion described above, and “◯” indicates that there was no crack in the ground semiconductor wafer, and “×” indicates that the part was cracked.

  The adhesive strength, gel fraction, and peelability in each Example and Comparative Example are summarized in Tables 1 and 2 below.

As shown in Tables 1 and 2, Comparative Examples 1 to 3 all had poor thin film grindability, and Comparative Examples 2 and 3 also had adhesive residue. In Comparative Example 3, dust intrusion was observed in addition to this.
In Comparative Examples 2 and 3, the peeling after heating was judged from the ratio of the adhesive strength at 50 ° C. to the adhesive strength at 25 ° C., and the peeling force was the target level, but the adhesive residue and the thin film grindability However, when the adhesive strength at 25 ° C. was lowered as in Comparative Example 1, the adhesive residue was improved, but the thin film grindability was not improved, and the dust penetration was not improved or deteriorated.
In Comparative Example 2, the adhesion to unevenness was superior from the evaluation result of dust intrusion, but the elastic modulus was controlled with a crosslinking agent, and the cohesive force of the adhesive was insufficient, leading to adhesive residue.
These results are mainly due to the low gel fraction and non-aqueous emulsion.
On the other hand, in Examples 1 to 7, water-based emulsion adhesives showed good characteristics because the physical properties were controlled not by controlling the elastic modulus using a crosslinking agent but by controlling the monomer ratio and gel fraction.

  As is apparent from the above results, the adhesive tape for processing a semiconductor wafer of the present invention can be used for the purpose of protecting the pattern surface when the semiconductor wafer is back-ground, and the paste on the pattern surface after the thin film grinding process. It can be seen that it is suitable for use in grinding because it has a high effect of suppressing the remainder and is easy to peel off.

DESCRIPTION OF SYMBOLS 1 Base film 2 Adhesive layer 3 Wafer pattern surface (wiring layer)
4 Wafer Si layer 5 Adhesive tape test piece 6 SUS steel plate 7 Tensile tester

Claims (6)

  A pressure-sensitive aqueous emulsion-type pressure-sensitive adhesive layer on at least one surface of a base film made of a resin, the gel fraction of the dispersion polymer of the aqueous emulsion-type pressure-sensitive adhesive is 80% or more, and 25 ° C. The adhesion to the SUS280 polished surface at the time of peeling at 0.8 to 2.5 N / 25 mm, and the adhesive strength to the SUS280 polished surface at the time of heat peeling at 50 ° C. is the SUS280 polished surface at the time of peeling at 25 ° C. An adhesive tape for protecting a semiconductor wafer surface, wherein the average particle size of the dispersed polymer in the adhesive is 0.13 to 0.18 μm.   The pressure-sensitive aqueous emulsion-type pressure-sensitive adhesive layer does not contain a crosslinking agent, and the semiconductor wafer surface protecting pressure-sensitive adhesive tape according to claim 1.   3. The semiconductor wafer surface according to claim 1, wherein the dispersion polymer is composed of only atoms selected from a carbon atom, a hydrogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, and an alkali metal atom. Protective adhesive tape.   4. The semiconductor wafer according to claim 1, wherein a main component of a polymer contained in the aqueous emulsion-type pressure-sensitive adhesive of the pressure-sensitive adhesive layer is a (meth) acrylic copolymer. Adhesive tape for surface protection.   The adhesive tape for protecting a semiconductor wafer surface according to any one of claims 1 to 4, wherein the dispersion polymer has at least methyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate as monomer components.   6. The semiconductor wafer surface according to claim 1, wherein the pressure-sensitive adhesive layer contains at least two kinds of compounds selected from a polypropylene glycol compound and a polyoxyalkylene alkylphenyl ether. Protective adhesive tape.

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