JP6851689B2 - Back grind tape - Google Patents

Description

The present invention relates to a back grind tape.

Conventionally, when processing a semiconductor wafer, a back grind step of grinding the back surface of the semiconductor wafer to a desired thickness is performed, and further, a wet etching step is performed for adjusting the semiconductor wafer surface and the like. In the back grind process, an adhesive tape (back grind tape) is used to fix the semiconductor wafer and protect the surface opposite to the ground surface (for example, Patent Document 1).

In recent years, as power devices have become thinner, there has been an increasing demand for thinner semiconductor wafers after the back grind process or the wet etching process. The backgrinding tape is peeled off after a predetermined step, but when the conventional backgrinding tape is used, there is a problem that the thin semiconductor wafer is frequently damaged when the tape is peeled off. Further, the conventional backgrinding tape has a low chemical resistance and has a problem that it is deteriorated by an acidic liquid or an alkaline liquid used in the wet etching step.

Japanese Unexamined Patent Publication No. 2011-151163

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to have an adhesive force suitable for a backgrinding process, excellent peelability, and acid resistance and alkali resistance. It is to provide excellent back grind tape.

The back grind tape of the present invention comprises a base material and a pressure-sensitive adhesive layer arranged on at least one side of the base material, the pressure-sensitive adhesive layer containing a (meth) acrylic pressure-sensitive adhesive, and the (meth) acrylic. The based pressure-sensitive adhesive contains a (meth) acrylic polymer containing a structural unit having a side chain having 8 or more carbon atoms, and the gel content of the pressure-sensitive adhesive layer is 40% to 80%.
In one embodiment, the substrate comprises a polyolefin-based resin or a polystyrene-based resin.

According to the present invention, it is possible to provide a backgrinding tape which has an appropriate adhesive force for a backgrinding step, is excellent in peelability, and is excellent in acid resistance or alkali resistance.

It is the schematic sectional drawing of the back grind tape by one Embodiment of this invention.

A. Overall configuration of the back grind tape FIG. 1 is a schematic cross-sectional view of the back grind tape according to one embodiment of the present invention. The back grind tape 100 includes a base material 10 and an adhesive layer 20 arranged on at least one side of the base material 10. Although not shown, the backgrinding tape of the present invention may be provided with a release liner on the outside of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface until it is used.

The thickness of the back grind tape is preferably 50 μm to 500 μm, and more preferably 150 μm to 350 μm. Within such a range, a back grind tape capable of improving the back surface grinding accuracy of the semiconductor wafer can be obtained.

The adhesive strength of the back grind tape at 25 ° C. is preferably 0.1 N / 20 mm to 5 N / 20 mm, and more preferably 0.2 N / 20 mm to 3 N / 20 mm. In this specification, the adhesive strength is a method according to JIS Z 0237 (2000) using a mirror wafer (made of silicon) as a test plate (bonding condition: 1 reciprocation of 2 kg roller, aging: 1 hour under measurement temperature). , Peeling speed: 300 mm / min, peeling angle: 90 °).

B. Adhesive layer The adhesive layer contains a (meth) acrylic adhesive. The (meth) acrylic pressure-sensitive adhesive may be a curable pressure-sensitive adhesive such as a thermosetting pressure-sensitive adhesive or an active energy ray-curable pressure-sensitive adhesive, or may be a pressure-sensitive pressure-sensitive adhesive. A curable pressure-sensitive adhesive is preferably used. If a curable pressure-sensitive adhesive is used, a back grind tape with less adhesive residue can be obtained.

The (meth) acrylic pressure-sensitive adhesive contains a (meth) acrylic polymer as a base polymer. The "base polymer" refers to the main component of the polymer contained in the pressure-sensitive adhesive. Further, in this specification, the “main component” refers to a component contained in an amount of more than 50% by weight unless otherwise specified.

The (meth) acrylic polymer contains a structural unit having a side chain having 8 or more carbon atoms. Such a (meth) acrylic polymer contains, for example, an alkyl (meth) acrylate having a branched or linear alkyl group having 8 or more carbon atoms as a main monomer and is copolymerizable with the main monomer. A polymer of a monomer raw material containing a submonomer having is preferable. Here, the main monomer means a component that occupies more than 50% by weight of the monomer composition in the above-mentioned monomer raw material.

In the present invention, a pressure-sensitive adhesive layer having excellent acid resistance and alkali resistance is formed by using a (meth) acrylic polymer containing a structural unit having a side chain having 8 or more carbon atoms. Further, according to the back grind tape of the present invention provided with the pressure-sensitive adhesive layer, the back grind tape is attached to an adherend (semiconductor wafer) to form a laminate, and the laminate is used as an acidic liquid or an alkaline liquid. It is possible to prevent an acidic liquid or an alkaline liquid from infiltrating between the adherend and the pressure-sensitive adhesive layer even when the material is immersed in the adhesive layer. Furthermore, since the pressure-sensitive adhesive layer has excellent adhesion to a base material having excellent acid resistance and alkali resistance (for example, a base material formed of polyolefin or polystyrene), the base material and the pressure-sensitive adhesive layer are combined. If the back grind tape is constructed, the effect of the present invention becomes more remarkable. Further, by using the (meth) acrylic polymer, it is possible to obtain a backgrinding tape which has an appropriate adhesive force in the backgrinding process, has excellent peelability, and can be peeled off without adhesive residue.

Examples of the alkyl (meth) acrylate having a branched or linear alkyl group having 8 or more carbon atoms include 2-ethylhexyl acrylate (2EHA), octyl (meth) acrylate, isooctyl (meth) acrylate, and nonyl ( Examples thereof include meta) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate (LA), and stearyl (meth) acrylate.

The content ratio of the structural unit derived from the alkyl (meth) acrylate having a branched or linear alkyl group having 8 or more carbon atoms is preferably 50 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. It is more preferably 60 parts by weight to 98 parts by weight, more preferably 70 parts by weight to 95 parts by weight, and further preferably 75 parts by weight to 85 parts by weight.

Examples of the sub-monomer include the following monomers. As the submonomer, only one type may be used alone, or two or more types may be used in combination.
Alkyl (meth) acrylate having a branched or linear alkyl group having 7 or less carbon atoms;
Carboxy group-containing monomer: Ethylene unsaturated monocarboxylic acid such as acrylic acid (AA), methacrylic acid (MAA), crotonic acid; ethylenically unsaturated dicarboxylic acid such as maleic acid, itaconic acid, citraconic acid and its anhydride. (Maleic anhydride, itaconic anhydride, etc.);
Hydroxyl-containing monomers: Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate; Unsaturated alcohols such as vinyl alcohols and allyl alcohols; ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and diethylene glycol monovinyl ether;
Amino group-containing monomers: for example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate;
Epoxy group-containing monomers: for example, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether;
Cyanide-containing monomers: eg acrylonitrile, methacrylonitrile;
Keto group-containing monomers: for example, diacetone (meth) acrylamide, diacetone (meth) acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetoacetate, vinyl acetoacetate;
Monomers having a nitrogen atom-containing ring: for example, N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazin, N-vinyl. Pyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholin, N-vinylcaprolactam, N- (meth) acryloylmorpholin;
Alkoxysilyl group-containing monomers: for example, 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- (meth) acryloxy. Propylmethyldiethoxysilane;
Isocyanate group-containing monomer: (meth) acryloyl isocyanate, 2- (meth) acryloyloxyethyl isocyanate, m-isopropenyl-α, α-dimethylbenzyl isocyanate.

The content ratio of the structural unit derived from the submonomer is less than 50 parts by weight, more preferably 2 parts by weight to 40 parts by weight, still more preferably 5 parts by weight, based on 100 parts by weight of the (meth) acrylic polymer. Parts to 30 parts by weight. Within such a range, it is possible to form a pressure-sensitive adhesive layer having high cohesive force and excellent adhesion.

The weight average molecular weight of the (meth) acrylic polymer is preferably 200,000 to 3 million, more preferably 250,000 to 1,500,000. The weight average molecular weight can be measured by GPC (solvent: THF).

The pressure-sensitive adhesive may further contain any suitable additive. Examples of the additives include polymerization initiators, cross-linking agents, plasticizers, tackifiers, anti-aging agents, fillers, colorants, antistatic agents, surfactants and the like. The above additives may be used alone or in combination of two or more. When two or more kinds of additives are used, one kind may be added one by one, or two or more kinds of additives may be added at the same time. The blending amount of the additive can be set to any appropriate amount.

As the tackifier, any suitable tackifier is used. As the tackifier, for example, a tackifier resin is used. Specific examples of the tackifier resin include rosin-based tackifier resins (eg, unmodified rosin, modified rosin, rosinphenol-based resins, rosin ester-based resins, etc.) and terpene-based tackifier resins (eg, terpene-based resins, terpene phenols). Hydrocarbon-based resin, styrene-modified terpene-based resin, aromatic-modified terpene-based resin, hydrogenated terpene-based resin), hydrocarbon-based tackifier resin (for example, aliphatic hydrocarbon resin, aliphatic cyclic hydrocarbon resin, aromatic-based Hydrocarbon resins (for example, styrene resins, xylene resins, etc.), aliphatic / aromatic petroleum resins, aliphatic / alicyclic petroleum resins, hydrogenated hydrocarbon resins, kumaron resins, kumaron inden resins , Etc.), phenol-based tackifier resins (eg, alkylphenol-based resins, xylene formaldehyde-based resins, resoles, novolak, etc.), ketone-based tackifier resins, polyamide-based tackifier resins, epoxy-based tackifier resins, elastomer-based tackifier resins, etc. Can be mentioned. Of these, a phenol-based tackifier resin is preferable, and an alkylphenol-based tackifier resin is more preferable. If a tackifier composed of an alkylphenol-based resin is used, the gel fraction can be easily controlled while strengthening the pressure-sensitive adhesive. The tackifier may be used alone or in combination of two or more. The gel fraction of the pressure-sensitive adhesive layer can be adjusted depending on the type and blending amount of the pressure-sensitive adhesive. In other words, the type and blending amount of the tackifier may be appropriately set so that the gel fraction of the pressure-sensitive adhesive layer is in the following range (40% to 80%) depending on the type of the base polymer. preferable.

Any suitable cross-linking agent can be used as the cross-linking agent. For example, isocyanate-based cross-linking agent, epoxy-based cross-linking agent, melamine-based cross-linking agent, peroxide-based cross-linking agent, urea-based cross-linking agent, metal alkoxide-based cross-linking agent, metal chelate-based cross-linking agent, metal salt-based cross-linking agent, carbodiimide-based cross-linking. Examples thereof include agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, and amine-based cross-linking agents. Only one type of cross-linking agent may be used, or two or more types may be used in combination. The amount of the cross-linking agent used can be set to an arbitrary appropriate value according to the intended use. In one embodiment, the amount of the cross-linking agent used is preferably 10 parts by weight or less, more preferably 0.1 parts by weight or more and less than 1 part by weight, based on 100 parts by weight of the (meth) acrylic polymer. Yes, more preferably 0.1 parts by weight or more and less than 0.5 parts by weight. In another embodiment, the amount of the cross-linking agent used is preferably 10 parts by weight or less, more preferably 0.1 parts by weight to 3 parts by weight, still more preferably, based on 100 parts by weight of the base polymer. It is 0.2 parts by weight or more and less than 1.5 parts by weight. It is preferable to use an appropriate amount of the cross-linking agent so that the gel fraction of the pressure-sensitive adhesive layer is in the following range (40% to 80%) depending on the type of the base polymer.

The gel fraction of the pressure-sensitive adhesive layer is preferably 40% to 80%, more preferably 42% to 78%, and even more preferably 60% to 76%. Within such a range, even when a back grind tape is attached to an adherend (semiconductor wafer) to form a laminate and the laminate is immersed in an acidic liquid or an alkaline liquid, the adherend is formed. It is possible to prevent an acidic liquid or an alkaline liquid from entering between the adhesive layer and the pressure-sensitive adhesive layer. In addition, it is possible to obtain a backgrinding tape that has appropriate adhesive strength in the backgrinding process, has excellent peelability, and can be peeled off without adhesive residue. The gel fraction is measured as follows. Approximately 0.1 g of the adhesive layer is wrapped in a Teflon (registered trademark) sheet (trade name "NTF1122", manufactured by Nitto Denko KK) with holes having a diameter of 0.2 μm, and then tied with a kite string. The weight is measured, and the weight is taken as the weight before immersion. The weight before immersion is the total weight of the pressure-sensitive adhesive layer, the Teflon sheet, and the kite string. In addition, the weight of the Teflon sheet to be used and the kite string is also measured, and the weight is taken as the package weight. Next, the pressure-sensitive adhesive layer is wrapped with a Teflon sheet, tied with a kite string, placed in a 50 ml container filled with ethyl acetate, and allowed to stand at room temperature for 1 week. Then, the Teflon sheet is taken out from the container and dried at 130 ° C. for 2 hours in a dryer to remove ethyl acetate, and then the sample weight is measured and the weight is taken as the weight after immersion. Then, the gel fraction is calculated from the following formula. In the following formula, A is the weight after immersion, B is the weight of the packaging bag, and C is the weight before immersion.
Gel fraction (% by weight) = (AB) / (CB) x 100

The storage elastic modulus G'of the pressure-sensitive adhesive layer at 23 ° C. is preferably 0.05 × 10 ⁶ Pa to 1.0 × 10 ⁸ Pa, and more preferably 0.1 × 10 ⁶ Pa to 1.0 ×. It is 10 ⁷ Pa. A back grind tape provided with an adhesive layer having such a storage elastic modulus can contribute to the achievement of excellent grinding accuracy in the back grind process, and has a small amount of adhesive residue. The storage elastic modulus G'can be measured under the following measurement conditions using an evaluation sample (adhesive layer) having a width of 10 mm, a length of 50 mm, and a thickness of 2 mm using a viscoelasticity measuring device.
-Mode: Torsion mode-Plate diameter: 7.9 mmφ
-Strain: 1% (25 ° C)
・ Frequency: 1Hz
-Measurement range: -20 ° C to 100 ° C

The thickness of the pressure-sensitive adhesive layer is preferably 10 μm to 200 μm, more preferably 15 μm to 150 μm.

C. The material for the substrate the substrate, any appropriate material can be selected. Examples of the material constituting the base material include resin-based materials (for example, sheet-like, net-like, woven fabric, non-woven fabric, foam sheet), paper, metal and the like. The base material may be a single layer or may be a plurality of layers composed of the same material or different materials. Specific examples of the resin constituting the base material include polyester, polyolefin, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester copolymer, and the like. Ethylene-butene copolymer, ethylene-hexene copolymer, polyurethane, polyether ketone, polyvinyl alcohol, polyvinylidene chloride, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyamide, polyimide, cellulose-based Examples thereof include resins, fluorine-based resins, silicone resins, polyethers, polystyrene-based resins (polystyrene and the like), polycarbonates, polyether sulfones, and crosslinked products thereof.

In one embodiment, as the base material, a base material composed of a polyolefin-based resin or a polystyrene-based resin is used. By using such a base material, a backgrinding tape having excellent acid resistance and alkali resistance can be obtained. Specific examples of the polyolefin-based resin include polypropylene, polyethylene, polybutene, and copolymers thereof. As the base material, a stretched film composed of the above resin may be used.

The base material may have a multi-layer structure. In one embodiment, a base material containing a layer composed of a polyolefin-based resin and a layer composed of another resin is used. Examples of other resins that can be combined with the polyolefin-based resin include ethylene-vinyl acetate copolymers and ethylene (meth) acrylate copolymers (EE (M) A, EM (M) A, EB (M) A) and the like. Can be mentioned. Of these, an ethylene-vinyl acetate copolymer is preferable. If a layer composed of the above-mentioned copolymer is adopted as one layer in the multilayer structure, a base material having excellent flexibility can be formed. The base material can exhibit a function of cushioning an impact during back grind (a function of preventing cracking and chipping).

The base material can be produced by any suitable method. For example, it can be manufactured by a method such as calendar film forming, casting film forming, inflation extrusion, T-die extrusion, or the like. Further, if necessary, it may be produced by performing a stretching treatment.

Depending on the purpose, the base material may be subjected to any appropriate surface treatment. Examples of the surface treatment include chromic acid treatment, ozone exposure, flame exposure, high-voltage impact exposure, ionizing radiation treatment, mat treatment, corona discharge treatment, primer treatment, and cross-linking treatment.

The thickness of the base material is preferably 10 μm to 300 μm, more preferably 30 μm to 200 μm.

The tensile elastic modulus (Young's modulus) of the base material at 23 ° C. is preferably 1 × 10 ⁶ Pa to 1 × 10 ¹¹ Pa, and more preferably 1 × 10 ⁷ Pa to 1 × 10 ^{10 Pa.} The tensile elastic modulus can be measured according to JIS K 7161: 2008 (grasping interval: 50 mm, tensile speed: 300 mm / min).

D. Method for Producing Backgrinding Tape The backgrinding tape of the present invention can be manufactured by applying the above-mentioned adhesive on the above-mentioned base material. Adhesive coating methods include bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexographic printing, etc. Various methods such as screen printing can be adopted. Alternatively, a method of separately forming an adhesive layer on the release liner and then laminating it to the base material may be adopted.

When a curable pressure-sensitive adhesive is used as the pressure-sensitive adhesive, the pressure-sensitive adhesive layer may be cured to adjust the characteristics (adhesive strength, elastic modulus, etc.) of the pressure-sensitive adhesive layer. Examples of the curing treatment include ultraviolet irradiation, heat treatment and the like.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples. Further, in the examples, unless otherwise specified, "parts" and "%" are based on weight.

[Production Example 1] (Meta) Acrylic Polymer (I)
2. 64.2 parts by weight of 2-ethylhexyl acrylate (2EHA), 16.5 parts by weight of acryloyl morpholine (ACMO), 11.4 parts by weight of hydroxyethyl acrylate (HEA), and 2-methacryloyloxyethyl isocyanate (MOI) 7. A (meth) acrylic polymer (I) having a weight average molecular weight (Mw) of about 900,000 by polymerizing 9 parts by weight (a (meth) acrylic polymer containing a structural unit having a side chain having 8 carbon atoms). Got

[Production Example 2] (Meta) Acrylic Polymer (II)
83.4 parts by weight of lauryl methacrylate (LMA), 8.5 parts by weight of 2-hydroxyethyl methacrylate (HEMA), and 8.1 parts by weight of 2-methacryloyloxyethyl isocyanate (MOI) are polymerized to achieve a weight average molecular weight. A (meth) acrylic polymer (II) having (Mw) of about 1 million (a (meth) acrylic polymer containing a structural unit having a side chain having 12 carbon atoms) was obtained.

[Production Example 3] (Meta) Acrylic Polymer (III)
A (meth) acrylic polymer (III) (carbon number) having a weight average molecular weight (Mw) of about 550,000 by polymerizing 100 parts by weight of 2-ethylhexyl acrylate (2EHA) and 4 parts by weight of hydroxyethyl acrylate (HEA). A (meth) acrylic polymer containing a structural unit having a side chain of 8) was obtained.

[Production Example 4] (Meta) Acrylic Polymer (IV)
41.6 parts by weight of butyl acrylate (BA), 36.2 parts by weight of hydroxyethyl acrylate (HEA), and 22.2 parts by weight of 2-methacryloyloxyethyl isocyanate (MOI) are polymerized to obtain a weight average molecular weight (Mw). ) Was about 500,000 (meth) acrylic polymer (IV) ((meth) acrylic polymer containing a structural unit having a side chain having 4 carbon atoms).

[Example 1]
(Preparation of adhesive A)
100 parts by weight of the (meth) acrylic polymer (I) obtained in Production Example 1, 3 parts by weight of a tackifier (alkylphenol-based tackifier resin; manufactured by Arakawa Chemical Industry Co., Ltd., trade name "Tamanor 526"), and a cross-linking agent. (Isocyanate-based cross-linking agent; manufactured by Toso Co., Ltd., trade name "Coronate HX") 0.1 part by weight and 3 parts by weight of photopolymerization initiator (manufactured by BASF, trade name "Irgacure 184") are mixed and adhered. Agent A was prepared.
(Preparation of base material)
A layer (thickness 30 μm) made of polypropylene (manufactured by Nippon Polypropylene, trade name “WSX02”) and an ethylene-vinyl acetate copolymer (manufactured by Mitsui DuPont, trade name “P1007”) are co-extruded using a T-die. A base material A composed of a layer made of (thickness 85 μm) was obtained.
(Making back grind tape)
The above pressure-sensitive adhesive A is applied to a separator (manufactured by Mitsubishi Chemical Corporation, trade name "MRF38") and heated at 120 ° C. for 2 minutes to form a pressure-sensitive adhesive layer (thickness: 20 μm), and the pressure-sensitive adhesive layer is used as a base material. Transferring to the ethylene-vinyl acetate copolymer film side of A gave a back grind tape composed of a base material and an adhesive layer.

[Example 2]
A back grind tape was obtained in the same manner as in Example 1 except that the amount of the cross-linking agent blended was 0.2 parts by weight.

[Example 3]
A back grind tape was obtained in the same manner as in Example 1 except that the amount of the cross-linking agent blended was 0.3 parts by weight.

[Example 4]
A back grind tape was obtained in the same manner as in Example 1 except that the tackifier was not blended.

[Example 5]
(Preparation of adhesive B)
100 parts by weight of the (meth) acrylic polymer (II) obtained in Production Example 2, 3 parts by weight of a tackifier (alkylphenol-based tackifier resin; manufactured by Arakawa Chemical Industry Co., Ltd., trade name "Tamanor 526"), and a cross-linking agent. (Isocyanate-based cross-linking agent; manufactured by Toso Co., Ltd., trade name "Coronate HL") 1 part by weight and 3 parts by weight of a photopolymerization initiator (manufactured by BASF, trade name "Irgacure 184") are mixed to prepare an adhesive B. Was prepared.
(Making back grind tape)
A back grind tape was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive B was used instead of the pressure-sensitive adhesive A.

[Example 6]
A backgrind tape was obtained in the same manner as in Example 5 except that the tackifier was not blended and the amount of the cross-linking agent blended was 0.2 parts by weight.

[Example 7]
A backgrind tape was obtained in the same manner as in Example 5 except that a base material made of stretched polystyrene (manufactured by Kurabo Industries, trade name "Oydis # 25"; thickness: 25 μm) was used instead of the base material A. It was.

[Example 8]
Back grind tape in the same manner as in Example 5 except that a base material made of polyethylene naphthalate (manufactured by Teijin Corporation, trade name "Theonex Q51 # 25"; thickness: 25 μm) was used instead of the base material A. Got

[Example 9]
A back grind tape was applied in the same manner as in Example 5 except that a base material made of polyimide (manufactured by Toray DuPont, trade name "Kapton 100V # 25"; thickness: 25 μm) was used instead of the base material A. Obtained.

[Example 10]
(Preparation of adhesive C)
100 parts by weight of the (meth) acrylic polymer (III) obtained in Production Example 3, 3 parts by weight of a tackifier (alkylphenol-based tackifier resin; manufactured by Arakawa Chemical Industries, Ltd., trade name "Tamanor 526"), and a cross-linking agent. (Isocyanate-based cross-linking agent; manufactured by Toso Co., Ltd., trade name "Coronate L") 0.2 parts by weight was mixed to prepare an adhesive C.
(Making back grind tape)
A back grind tape was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive C was used instead of the pressure-sensitive adhesive A.

[Comparative Example 1]
A backgrind tape was obtained in the same manner as in Example 1 except that the amount of the cross-linking agent blended was 1 part by weight.

[Comparative Example 2]
A backgrind tape was obtained in the same manner as in Comparative Example 1 except that the tackifier was not blended.

[Comparative Example 3]
A back grind tape was obtained in the same manner as in Example 1 except that the amount of the cross-linking agent blended was 0.5 parts by weight.

[Comparative Example 4]
A backgrind tape was obtained in the same manner as in Example 5 except that the amount of the cross-linking agent blended was 1.5 parts by weight.

[Comparative Example 5]
A backgrind tape was obtained in the same manner as in Example 5 except that the tackifier was not blended.

[Comparative Example 6]
(Preparation of adhesive D)
100 parts by weight of the (meth) acrylic polymer (IV) obtained in Production Example 4, 0.1 part by weight of a cross-linking agent (isocyanate-based cross-linking agent; manufactured by Tosoh Corporation, trade name "Coronate L"), and a photopolymerization initiator. (Manufactured by BASF, trade name "Irgacure 651") 3 parts by weight was mixed to prepare an adhesive D.
(Making back grind tape)
The above adhesive C is applied to a separator (manufactured by Mitsubishi Chemical Corporation, trade name "MRF38") and heated at 120 ° C. for 2 minutes to form an adhesive layer (thickness: 20 μm), and the adhesive layer is used as PET. Transferring was performed to obtain a back grind tape composed of a substrate and an adhesive layer.

[Evaluation]
The back grind tapes obtained in Examples and Comparative Examples were subjected to the following evaluations (1) to (4). The results are shown in Table 1.

(1) Gel fraction of the pressure-sensitive adhesive layer Approximately 0.1 g of the pressure-sensitive adhesive layer was wrapped in a Teflon (registered trademark) sheet (trade name "NTF1122", manufactured by Nitto Denko Co., Ltd.) having holes with a diameter of 0.2 μm. After that, it was tied with a kite string, the weight at that time was measured, and the weight was taken as the weight before immersion. The weight before immersion is the total weight of the pressure-sensitive adhesive layer, the Teflon sheet, and the kite string. In addition, the weights of the Teflon sheet and the kite string to be used were also measured, and the weight was taken as the package weight. Next, the pressure-sensitive adhesive layer was wrapped with a Teflon sheet, tied with a kite string, placed in a 50 ml container filled with ethyl acetate, and allowed to stand at room temperature for 1 week. Then, the Teflon sheet was taken out from the container and dried at 130 ° C. for 2 hours in a dryer to remove ethyl acetate, and then the sample weight was measured, and the weight was taken as the weight after immersion. The gel fraction was calculated from the following formula. In the following formula, A is the weight after immersion, B is the weight of the packaging bag, and C is the weight before immersion.
Gel fraction (% by weight) = (AB) / (CB) x 100

(2) Etching resistance (acid resistance and alkali resistance of back grind tape)
A 96 wt% H ₂ SO ₄ aqueous solution and a 70 wt% HNO ₃ aqueous solution were mixed (weight ratio: H ₂ SO ₄ / HNO ₃ = 50/7) to prepare a mixed acid. The backgrinding tape was immersed in the mixed acid (at room temperature) for 2 minutes.
Next, the backgrinding tape taken out from the mixed acid was immersed in a 45 wt% KOH aqueous solution (60 ° C.) for 1 minute.
After that, the back grind tape was washed with water, and visually confirmed the deterioration of the base material and the presence or absence of liquid intrusion into the adhesive layer. In Table 1, when the deterioration of the base material is not confirmed (including the deterioration to the extent that is practically acceptable), the case where the deterioration of the base material is confirmed (when the deterioration is not suitable for practical use) is ×. And. Further, the case where the liquid intrusion into the adhesive layer is not confirmed is evaluated as ◯, and the case where the liquid is confirmed is evaluated as ×.

(3) Adhesive residue The back grind tape is attached to the silicon wafer, and the hand peel of the back grind tape is applied at room temperature (23 ° C) while vacuum-adsorbing the wafer with a wafer holding device for hand peel (HMT-300 manufactured by Nitto Seiki). went. Then, the surface layer of the wafer after the back grind tape was peeled off was visually observed and observed with a 100x optical microscope to confirm the presence or absence of adhesive residue. In Table 1, the case where no adhesive residue is confirmed is evaluated as ◯, and the case where the adhesive residue is confirmed is evaluated as ×.

As is clear from Table 1, the backgrinding tape of the present invention forms an adhesive layer having excellent acid resistance or alkali resistance. Further, by using a specific resin as the material constituting the base material, it is possible to obtain a backgrind tape having excellent both the base material and the pressure-sensitive adhesive layer.

10 Base material 20 Adhesive layer 100 Back grind tape

Claims (3)

A base material and an adhesive layer arranged on at least one side of the base material are provided.
The pressure-sensitive adhesive layer contains a (meth) acrylic pressure-sensitive adhesive.
The (meth) acrylic pressure-sensitive adhesive comprises a (meth) acrylic polymer containing a structural unit having a side chain having 8 or more carbon atoms.
The (meth) acrylic polymer contains a structural unit derived from an alkyl (meth) acrylate having a branched or linear alkyl group having 8 or more carbon atoms, and has a branched or direct carbon number of 8 or more. The content ratio of the structural unit derived from the alkyl (meth) acrylate having a chain-like alkyl group exceeds 50 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer.
The gel fraction of the pressure-sensitive adhesive layer is 40% to 80%.
The tensile elastic modulus (Young's modulus) of the substrate at 23 ° C. is 1 × 10 ⁶ Pa to 1 × 10 ^{11 Pa.}
Back grind tape. The base material contains a polyolefin-based resin or a polystyrene-based resin.
The back grind tape according to claim 1. The back grind tape according to claim 1 or 2 , wherein the storage elastic modulus G'of the pressure-sensitive adhesive layer at 23 ° C. is 0.05 × 10 ⁶ Pa to 1.0 × 10 ^{8 Pa.}

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