JP7164351B2 - back grind tape - Google Patents

Description

The present invention relates to backgrinding tapes. More particularly, the present invention relates to a backgrinding tape that is preferably used in a backgrinding process performed after a dicing process.

A workpiece (for example, a semiconductor wafer), which is an assembly of electronic components, is manufactured with a large diameter, cut and separated (diced) into element pieces, and then transferred to a mounting process. In this dicing process, the work is cut into small pieces. In order to fix the workpiece after dicing, dicing is usually performed after bonding an adhesive tape (dicing tape) to the workpiece (for example, Patent Document 1). As one of the dicing methods, a method of dicing a workpiece with a laser beam is known. As such a dicing method, a method of condensing a laser beam on the surface of a workpiece to form grooves on the surface of the workpiece and then cutting the workpiece is frequently used. On the other hand, in recent years, stealth dicing has also been proposed in which a laser beam is focused inside a work, and the work is cut after reforming the work at that location.

In general, in the processing of semiconductor wafers, the back surface is ground to a predetermined thickness (for example, 100 μm to 600 μm) (back grinding step). Conventionally, after a pattern is formed on the front surface of a semiconductor wafer, the front surface is fixed to a back grinding tape, back grinding is performed, and then a dicing process is performed. On the other hand, in recent years, in order to increase the usefulness of the above-described stealth dicing, a technique of performing a backgrinding process by fixing the surface to a backgrinding tape after performing stealth dicing has been studied.

JP 2003-007646 A

If dicing is performed before the backgrinding process as described above, a new problem arises in that the chipped chips interfere with each other during the backgrinding, resulting in chipping.

An object of the present invention is to provide a backgrinding tape that is used in a backgrinding process that is performed after dicing, and that prevents chip chipping that may occur during backgrinding.

The back grind tape of the present invention comprises an adhesive layer, an intermediate layer, and a first base material in this order, and the material constituting the intermediate layer is a non-crosslinked acrylic resin having a carboxyl group. The adhesive layer has an initial adhesive force of 1 N/20 mm to 30 N/20 mm when the adhesive layer is attached to a Si mirror wafer.
In one embodiment, the backgrind tape further comprises a second substrate, the second substrate being disposed on the opposite side of the first substrate from the intermediate layer.
In one embodiment, the first substrate is made of polyethylene terephthalate.
In one embodiment, the second base material is made of polyolefin resin.
In one embodiment, the pressure-sensitive adhesive layer has a thickness of 1 μm to 50 μm.
In one embodiment, the intermediate layer has a thickness of 5 μm to 50 μm.
In one embodiment, the backgrinding tape is used for backgrinding a stealth diced semiconductor wafer.

According to the present invention, it is possible to provide a backgrinding tape that prevents tip chipping that may occur during backgrinding. The backgrinding tape of the present invention is particularly useful as a backgrinding tape used in a backgrinding step after dicing (preferably stealth dicing).

1 is a schematic cross-sectional view of a backgrind tape according to one embodiment of the present invention; FIG. FIG. 4 is a schematic cross-sectional view of a backgrind tape according to another embodiment of the present invention;

A. Overview of Backgrind Tape FIG. 1 is a schematic cross-sectional view of a backgrind tape according to one embodiment of the present invention. A back grind tape 100 according to this embodiment comprises an adhesive layer 10 , an intermediate layer 20 and a first substrate 31 . Although not shown, the back grind tape of the present invention may be provided with a release liner (not shown) on the outside of the pressure-sensitive adhesive layer for the purpose of protecting the pressure-sensitive adhesive surface until it is used. In addition, the back grind tape may further include any other appropriate layer as long as the effects of the present invention are obtained. Preferably, the intermediate layer is placed directly on the first substrate. Also preferably, the pressure-sensitive adhesive layer is placed directly on the intermediate layer.

The back grinding tape of the present invention can be suitably used for fixing a diced semiconductor wafer when back-grinding the semiconductor wafer, and is particularly suitable when stealth dicing is employed as the dicing. can be used for Stealth dicing means forming a modified layer inside a semiconductor wafer by laser light irradiation. The semiconductor wafer can be cut starting from the modified layer.

In the present invention, an adhesive layer and an intermediate layer are formed in combination, and an acrylic resin having a carboxyl group and not cross-linked is used as a material constituting the intermediate layer, so that the backing is performed after dicing. It is possible to provide a backgrinding tape which is used in a grinding process and which prevents chips from chipping during backgrinding. The back grind tape of the present invention constructed as described above is characterized in that it is difficult to deform against an external force in the surface direction, and it is difficult to return to its original shape after deformation. By using such a backgrinding tape, chips cut into small pieces after dicing can be prevented from excessively interfering with each other, and defects such as chipping of the chips can be prevented during backgrinding. The back grind tape of the present invention is particularly useful for semiconductor wafer processing, including stealth dicing.

FIG. 2 is a schematic cross-sectional view of a backgrinding tape according to another embodiment of the invention. The back grind tape 200 according to this embodiment has a two-layer base material and further includes a second base material 32 . The second substrate 32 is arranged on the opposite side of the first substrate 31 from the intermediate layer 20 . That is, the back grind tape 200 includes an adhesive layer 10, an intermediate layer 20, a first base material 31, and a second base material 32 in this order. Preferably, a substrate that is softer (eg, has a lower elastic modulus) than the first substrate is used as the second substrate. The back grinding tape according to the present embodiment can more preferably prevent defects such as chipping of chips during back grinding. In semiconductor wafer processing including stealth dicing, a crack (so-called BHC) extending from a degraded layer formed by a laser beam to the wafer surface is generated to break the semiconductor wafer into small pieces. It is possible to prevent defects such as chipping of chips not only in the embodiment, but also in the embodiment in which processing is more difficult, that is, in the embodiment in which the crack is generated during back grinding. Note that the base material may have a structure of three or more layers.

The initial adhesive force when the adhesive layer of the back grind tape of the present invention is attached to a Si mirror wafer is preferably 1 N/20 mm to 30 N/20 mm, more preferably 2 N/20 mm to 20 N/20 mm, More preferably 3 N/20 mm to 15 N/20 mm, particularly preferably 4 N/20 mm to 10 N/20 mm. Within such a range, it is possible to obtain a backgrinding tape that can satisfactorily fix a semiconductor wafer during backgrinding. The back grind tape of the present invention can be a tape whose adhesive strength can be reduced by irradiation with active energy rays (for example, ultraviolet rays). means previous stickiness. In the present invention, adhesive strength is measured according to JIS Z 0237:2000. Specifically, the adhesive strength is measured using a tensile tester (Tensilon, manufactured by Shimadzu Corporation) under the conditions of 23° C., peel speed of 300 mm/min, and peel angle of 180°.

The thickness of the back grind tape is preferably 35 μm to 500 μm, more preferably 60 μm to 300 μm, still more preferably 80 μm to 200 μm.

B. Substrate B-1. First Base Material A resin film is preferably used as the first base material. Examples of the resin constituting the resin film include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polypropylene (PP), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), Examples include polysulfone (PSF), polyetheretherketone (PEEK), polyarylate (PAR), and the like. Among them, polyester-based resins are preferred, and polyethylene terephthalate is particularly preferred. By using the first base material made of polyethylene terephthalate, it is possible to obtain a back grinding tape that can more preferably prevent defects such as chipping during back grinding.

The tensile elastic modulus of the first base material at 23° C. is preferably 50 MPa to 10000 MPa, more preferably 100 MPa to 5000 MPa. The tensile elastic modulus of the first base material (and each layer constituting the back grind tape (described later)) was measured using a tensile tester (manufactured by SHIMADZU, "AG-IS"), the distance between chucks: 50 mm, tensile Speed: 300 mm/min, sample width: 10 mm.

The thickness of the first base material is preferably 25 μm to 200 μm, more preferably 30 μm to 150 μm, even more preferably 40 μm to 100 μm, particularly preferably 40 μm to 80 μm.

The first substrate may further contain any suitable additive. Examples of additives include lubricants, antioxidants, ultraviolet absorbers, processing aids, fillers, antistatic agents, stabilizers, antibacterial agents, flame retardants, colorants and the like.

B-2. Second Base Material A resin film is preferably used as the second base material. Examples of the resin constituting the resin film include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polypropylene (PP), polyimide (PI), polyetherimide (PEI), polyphenylene sulfide (PPS), Examples include polysulfone (PSF), polyetheretherketone (PEEK), polyarylate (PAR), and the like. Polyolefin-based resins are particularly preferred.

In one embodiment, the second base material contains a polyethylene-based resin or a polypropylene-based resin. Examples of polyethylene-based resins include low-density polyethylene, linear polyethylene, medium-density polyethylene, high-density polyethylene, and ultra-low-density polyethylene. The content of ethylene-derived structural units in the polyethylene resin is preferably 80 mol % or more, more preferably 90 mol % or more, and still more preferably 95 mol % or more. Structural units other than ethylene-derived structural units include structural units derived from monomers copolymerizable with ethylene and copolymers, such as propylene, 1-butene, isobutene, 1-pentene, 2-methyl -1-butene, 3-methyl-1-butene, 1-hexene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1 -tetradecene, 1-hexadecene, 1-octadecene, 1-icosene and the like.

In one embodiment, a substrate composed of polyethylene terephthalate is used as the first substrate, and a polyolefin resin (preferably the polyethylene resin or polypropylene resin) is used as the second substrate. Use a substrate that is By using these base materials, problems such as chipping of chips during back grinding can be more preferably prevented.

The tensile elastic modulus of the second base material at 23° C. is preferably 50 MPa to 2000 MPa, more preferably 100 MPa to 1000 MPa.

It is preferable that the tensile elastic modulus of the second base material at 23°C is lower than the tensile elastic modulus of the first base material at 23°C. The tensile elastic modulus of the second substrate at 23°C is preferably 0.5% to 100%, more preferably 0.5%, relative to the tensile elastic modulus of the first substrate at 23°C. It is not less than 100%, more preferably 1% to 50%.

The thickness of the second base material is preferably 25 μm to 200 μm, more preferably 30 μm to 150 μm, even more preferably 40 μm to 100 μm, particularly preferably 40 μm to 80 μm.

The second substrate may further contain any suitable additive. Examples of additives include lubricants, antioxidants, ultraviolet absorbers, processing aids, fillers, antistatic agents, stabilizers, antibacterial agents, flame retardants, colorants and the like.

The first base material and the second base material can be laminated via any suitable adhesive layer. The thickness of the adhesive layer between these substrates is, for example, 2 μm to 10 μm.

C. Intermediate Layer The intermediate layer has a carboxyl group and is composed of an acrylic resin that is not crosslinked (for example, epoxy-crosslinked). Such an intermediate layer contains an acrylic resin having a carboxyl group in a side chain, and is formed from an intermediate layer-forming composition that does not contain a cross-linking compound such as a cross-linking agent that reacts with the carboxyl group to form a cross-linked structure. can be The acrylic resin constituting the intermediate layer is obtained by polymerizing a monomer component containing a (meth)acrylic acid alkyl ester and a carboxyl group-containing monomer. (a structural unit having a carboxyl group in the side chain). The presence or absence of cross-linking of the acrylic resin can be confirmed by pyrolysis GC/MS analysis.

Examples of the (meth)acrylic acid alkyl esters include n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, and (meth)acrylic acid. Pentyl acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) ) nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, (meth)acrylate Alkyl groups such as tetradecyl acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate (Meth)acrylic acid alkyl esters having a straight-chain or branched-chain alkyl group having 4 to 20 carbon atoms and the like can be mentioned. Among these, from the viewpoint of adhesiveness to adherends and bonding workability, (meth)acrylic acid alkyl esters having 5 to 12 carbon atoms in the alkyl group are preferable, more preferably n-butyl acrylate or acrylic Acid 2-ethylhexyl (2EHA). (Meth)acrylic acid alkyl esters may be used alone or in combination of two or more.

In the acrylic resin, the content of structural units derived from (meth)acrylic acid alkyl ester is preferably 70 parts by weight to 98 parts by weight, more preferably 85 parts by weight, with respect to 100 parts by weight of the acrylic resin. ~96 parts by weight.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as acrylic acid (AA), methacrylic acid (MAA) and crotonic acid; ethylenically unsaturated dicarboxylic acids such as maleic acid, itaconic acid and citraconic acid. etc. The acrylic resin has a carboxyl group in its side chain, and the backgrinding tape having an intermediate layer made of such an acrylic resin prevents tip chipping that may occur during backgrinding. Carboxy group-containing monomers can be used alone or in combination of two or more.

In the acrylic resin, the content ratio of the structural unit derived from the carboxyl group-containing monomer is preferably 2 parts by weight to 30 parts by weight, more preferably 4 parts by weight to 15 parts by weight, with respect to 100 parts by weight of the acrylic resin. parts, particularly preferably 4 to 8 parts by weight. Further, the content ratio of the structural unit derived from the carboxyl group-containing monomer is preferably 2 parts by weight to 30 parts by weight, more preferably 5 parts by weight, with respect to 100 parts by weight of the structural unit derived from the (meth)acrylic acid alkyl ester. parts to 20 parts by weight, more preferably 5 parts to 10 parts by weight.

The acrylic resin may, if necessary, contain structural units derived from other monomers copolymerizable with the (meth)acrylic acid alkyl ester. Other monomers include the following monomers. These monomers can be used singly or in combination of two or more.
hydroxyl group-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 alcohol and allyl alcohol; 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;
cyano group-containing monomers: e.g. 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: such as N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinyl pyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(meth)acryloylmorpholine;
Alkoxysilyl group-containing monomers: such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxy Propylmethyldiethoxysilane.

In the acrylic resin, the content of structural units derived from other monomers is preferably 40 parts by weight or less, more preferably 20 parts by weight or less, and still more preferably 100 parts by weight of the acrylic resin. It is 10 parts by weight or less.

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

The intermediate layer-forming composition may further contain any appropriate additive. Examples of the additives include plasticizers, tackifiers, antioxidants, 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 additives are used, they may be added one by one, or two or more additives may be added simultaneously. The blending amount of the additive can be set to any appropriate amount.

The thickness of the intermediate layer is preferably 5 μm to 50 μm, more preferably 10 μm to 40 μm, still more preferably 15 μm to 30 μm. With such a range, it is possible to more preferably prevent defects such as tip chipping during back grinding.

The thickness of the intermediate layer is preferably 2 to 20 times, more preferably 3 to 10 times, and further preferably 3 to 7 times the thickness of the pressure-sensitive adhesive layer. preferable. If the intermediate layer and the pressure-sensitive adhesive layer are configured with such a thickness relationship, the back grind tape is less likely to be deformed by an external force in the surface direction, and is also less likely to return to its original shape after being deformed. can be obtained.

The storage modulus E' of the intermediate layer at 23°C is preferably 200 MPa or less, more preferably 30 MPa to 180 MPa, still more preferably 50 MPa to 160 MPa. Within such a range, it is possible to obtain a back grinding tape that is particularly excellent in followability to an uneven surface. The storage modulus E' can be measured by the nanoindentation method. The measurement conditions are as follows.
(Measuring device and measurement conditions)
Equipment: Hysitron Inc. Manufactured by Tribo Indexer
Indenter used: Berkovich (triangular pyramid type)
Measurement method: single indentation measurement Measurement temperature: 25°C
Indentation depth setting: about 300 nm
Indentation speed: about 10 nm/sec
Frequency: 100Hz
Measurement atmosphere: in air Sample size: about 1 cm x about 1 cm

The tensile elastic modulus of the intermediate layer at 23° C. is preferably 0.05 MPa to 10 MPa, more preferably 0.1 MPa to 5 MPa, still more preferably 0.2 MPa to 3 MPa. Within this range, it is possible to more preferably prevent defects such as chipping of chips during back grinding, in combination with the use of a specific material as the material forming the intermediate layer.

D. Adhesive Layer The adhesive layer may be composed of any appropriate adhesive. Examples of adhesives include acrylic adhesives, rubber adhesives, silicone adhesives, polyvinyl ether adhesives, and the like. The adhesive may be a curable adhesive such as a thermosetting adhesive or an active energy ray-curable adhesive, or may be a pressure-sensitive adhesive. A curable adhesive is preferably used. If a curable adhesive is used, it is possible to obtain a backgrinding tape that can be easily peeled off by curing the adhesive layer when backgrinding is required, and then by curing the semiconductor wafer.

In one embodiment, an acrylic adhesive is used as the adhesive. Preferably, the acrylic pressure-sensitive adhesive is a curable type.

Acrylic pressure-sensitive adhesives contain an acrylic polymer as a base polymer. The acrylic polymer may have structural units derived from (meth)acrylic acid alkyl esters. Examples of the (meth)acrylic acid alkyl esters include n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, and (meth)acrylic acid. Pentyl acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) ) nonyl acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, (meth)acrylate Alkyl groups such as tetradecyl acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate (Meth)acrylic acid alkyl esters having a straight-chain or branched-chain alkyl group having 4 to 20 carbon atoms and the like can be mentioned. Among these, from the viewpoint of adhesiveness to adherends and bonding workability, (meth)acrylic acid alkyl esters having 5 to 12 carbon atoms in the alkyl group are preferable, more preferably n-butyl acrylate or acrylic Acid 2-ethylhexyl (2EHA). (Meth)acrylic acid alkyl esters may be used alone or in combination of two or more.

The acrylic polymer may optionally contain structural units derived from other monomers copolymerizable with the (meth)acrylic acid alkyl ester. Other monomers include the following monomers. These monomers can be used singly or in combination of two or more.
Carboxy group-containing monomers and their anhydrides: ethylenically unsaturated monocarboxylic acids such as acrylic acid (AA), methacrylic acid (MAA), crotonic acid; ethylenically unsaturated dicarboxylic acids such as maleic acid, itaconic acid, citraconic acid and anhydrides thereof (maleic anhydride, itaconic anhydride, etc.);
hydroxyl group-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 alcohol and allyl alcohol; 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, methylglycidyl (meth)acrylate, allyl glycidyl ether;
cyano group-containing monomers: e.g. 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: such as N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinyl pyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(meth)acryloylmorpholine;
Alkoxysilyl group-containing monomers: such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxy propylmethyldiethoxysilane;
Isocyanate group-containing monomers: (meth)acryloyl isocyanate, 2-(meth)acryloyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate.

In the acrylic polymer, the content of structural units derived from the other monomers is less than 50 parts by weight, more preferably 2 parts by weight to 40 parts by weight, with respect to 100 parts by weight of the acrylic polymer. It is preferably 5 to 30 parts by weight.

The weight average molecular weight of the acrylic polymer is preferably 200,000 to 3,000,000, more preferably 250,000 to 1,500,000.

The adhesive may further contain any appropriate additive. Examples of the additives include photopolymerization initiators, cross-linking agents, plasticizers, tackifiers, anti-aging agents, fillers, colorants, antistatic agents, and surfactants. The above additives may be used alone or in combination of two or more. When two or more additives are used, they may be added one by one, or two or more additives may be added simultaneously. The blending amount of the additive can be set to any appropriate amount.

In one embodiment, the adhesive further contains a photopolymerization initiator. Any appropriate initiator can be used as the photopolymerization initiator. Examples of photopolymerization initiators include acylphosphine oxide photoinitiators such as ethyl 2,4,6-trimethylbenzylphenylphosphinate, (2,4,6-trimethylbenzoyl)-phenylphosphine oxide; α-ketols such as -hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, 1-hydroxycyclohexylphenyl ketone, etc. Acetophenones such as methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1, etc. benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; ketal compounds such as benzyl dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; 1-phenone-1 , 1-propanedione-2-(o-ethoxycarbonyl) oxime and other photoactive oxime compounds; benzophenone, benzoylbenzoic acid, benzophenone compounds such as 3,3'-dimethyl-4-methoxybenzophenone; thioxanthone, 2- Chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone thioxanthone-based compounds such as sulfonate; camphorquinone; halogenated ketones; acylphosphonates and the like. Among them, acylphosphine oxide photoinitiators are preferred. The amount of the photopolymerization initiator used is preferably 1 part by weight to 20 parts by weight, more preferably 2 parts by weight to 15 parts by weight, and still more preferably 3 parts by weight with respect to 100 parts by weight of the acrylic polymer. ~10 parts by weight.

In one embodiment, the adhesive further comprises a cross-linking agent. Any appropriate cross-linking agent can be used as the cross-linking agent. For example, isocyanate-based cross-linking agents, epoxy-based cross-linking agents, melamine-based cross-linking agents, peroxide-based cross-linking agents, urea-based cross-linking agents, metal alkoxide-based cross-linking agents, metal chelate-based cross-linking agents, metal salt-based cross-linking agents, carbodiimide-based cross-linking agents cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, and amine-based cross-linking agents. The cross-linking agent may be used alone or in combination of two or more. The amount of the cross-linking agent used can be set to any appropriate value depending on the intended use. The amount of the cross-linking agent used is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, and still more preferably 1 part by weight with respect to 100 parts by weight of the acrylic polymer. parts by weight to 3 parts by weight.

In one embodiment, an isocyanate-based cross-linking agent is preferably used. An isocyanate-based cross-linking agent is preferable because it can react with various functional groups. Specific examples of the isocyanate-based cross-linking agents include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; aromatic isocyanates such as tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name “Coronate L”), tri Methylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HL"), hexamethylene diisocyanate isocyanurate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "Coronate HX"), etc. isocyanate adduct; and the like. Preferably, a cross-linking agent having 3 or more isocyanate groups is used.

The thickness of the pressure-sensitive adhesive layer is preferably 1 μm to 50 μm, more preferably 1 μm to 25 μm, still more preferably 1 μm to 5 μm. With such a range, it is possible to more preferably prevent defects such as tip chipping during back grinding.

The storage modulus E' of the pressure-sensitive adhesive layer at 23°C is preferably 15 MPa to 200 MPa, more preferably 20 MPa to 150 MPa, still more preferably 30 MPa to 120 MPa. Within such a range, it is possible to obtain a back grinding tape that is particularly excellent in followability to an uneven surface.

The tensile modulus of the pressure-sensitive adhesive layer at 23° C. is preferably 0.01 MPa to 2 MPa, more preferably 0.05 MPa to 1 MPa, still more preferably 0.1 MPa to 0.5 MPa. With such a range, it is possible to more preferably prevent defects such as tip chipping during back grinding. When the pressure-sensitive adhesive layer is of a curable type, it is preferable that the tensile modulus of elasticity of the pressure-sensitive adhesive layer before curing is within the above range.

E. Manufacturing Method of Backgrind Tape The backgrind tape can be manufactured by any appropriate method. The back grind tape is produced, for example, by coating (applying and drying) the composition for forming an intermediate layer on a base material (first base material) to form an intermediate layer, and then applying the adhesive on the intermediate layer. It can be obtained by coating (applying and drying) the agent to form an adhesive layer. 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, screen printing, etc. Various methods can be employed. Alternatively, a method of separately forming the pressure-sensitive adhesive layer and the intermediate layer on a release liner and then transferring and laminating the same may be adopted.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples. Tests and evaluation methods in Examples are as follows. Also, "parts" and "%" are by weight unless otherwise specified.

(1) Adhesion A sample was prepared by cutting a back grind tape into strips with a width of 20 mm.
The above sample was subjected to a 180° peeling test in accordance with JIS Z 0237 under the following conditions to measure the adhesive strength of the back grind tape.
<180° peeling test>
Adherend: Si mirror wafer Number of repeated tests: 3 Temperature: 23°C
Peeling angle: 180 degrees Peeling speed: 300 mm/min
Initial length (chuck interval): 150 mm

(2) Evaluation of cracks (chip chipping) On one side of a 12-inch Si mirror wafer (thickness: 775 μm), a back grind tape was attached under the following conditions, and then the side opposite to the back grind tape attached surface. Therefore, stealth dicing was performed under the following conditions to form a modified layer inside the mirror wafer with the intention of obtaining 680 small pieces of 8 mm×12 mm.
Then, back grinding was performed under the following conditions so that the mirror wafer had a thickness of 25 μm.
Then, the back-grinded mirror wafer was mounted on a dicing tape (manufactured by Nitto Denko Co., Ltd., trade name "NLS-516P") and a ring frame by in-line transportation.
After that, the surface of the mirror wafer was observed with an optical microscope (x200) through the dicing tape to confirm the presence or absence of cracks. A crack evaluation was performed by
<Stealth dicing conditions>
Apparatus: DFL7361 SDE06 manufactured by Disco
Treatment conditions: BHC, non-BHC
<Conditions for applying back grind tape>
Device: Nitto Seiki DR-3000III
Pressure: 0.3MPa
Temperature: Room temperature Speed: 10mm/min
<Background conditions>
Apparatus: DGP8761 DFM2800 in-line grinder Z1 (#360) and Z2 (#2000) manufactured by Disco Co., Ltd. After forming a thin film, GDP (gettering DP processing) was performed.

(3) Storage Elastic Modulus The storage elastic modulus E' of the intermediate layer and the adhesive layer was measured by the nanoindentation method under the following conditions.
<Measurement of storage elastic modulus E'>
Equipment: Hysitron Inc. Manufactured by Tribo Indexer
Indenter used: Berkovich (triangular pyramid type)
Measurement method: single indentation measurement Measurement temperature: 23°C
Indentation depth setting: about 300 nm
Indentation speed: about 10 nm/sec
Frequency: 100Hz
Measurement atmosphere: in air Sample size: about 1 cm x about 1 cm

[Production Example 1] Preparation of intermediate layer forming composition M1 2 30 parts by weight of ethylhexyl acrylate, 70 parts by weight of methyl acrylate, 10 parts by weight of acrylic acid, 0.1 parts by weight of azobisisobutyronitrile, and acetic acid A mixture obtained by mixing with 100 parts by weight of ethyl was polymerized at 60° C. for 6 hours in a nitrogen atmosphere to obtain an acrylic resin M1 having a weight average molecular weight of 500,000.
The polymerization liquid obtained by the above operation was used as intermediate layer forming composition M1.

[Production Example 2] Preparation of intermediate layer forming composition M2 50 parts by weight of butyl acrylate, 50 parts by weight of ethyl acrylate, 5 parts by weight of acrylic acid, 0.1 parts by weight of azobisisobutyronitrile, and ethyl acetate A mixture obtained by mixing 100 parts by weight of the above was polymerized at 60° C. for 6 hours in a nitrogen atmosphere to obtain an acrylic resin M2 having a weight average molecular weight of 650,000.
The polymerization liquid obtained by the above operation was used as intermediate layer forming composition M2.

[Production Example 3] Preparation of Intermediate Layer-Forming Composition M3 , trade name "ADEKA POLYETHER EDP-300") was mixed with 0.05 parts by weight to obtain a composition containing a reactant produced by the reaction of these compounds.
1.05 parts by weight of the obtained composition was added to intermediate layer forming composition M1 (acrylic resin M1 content: 100 parts by weight) prepared in Production Example 1 to obtain intermediate layer forming composition M3. prepared.
Note that the reaction product does not crosslink the acrylic resin.

[Production Example 4] Preparation of Intermediate Layer-Forming Composition M1′ An epoxy-based cross-linking agent (manufactured by Mitsubishi Gas Co., Ltd., trade name “Tetrad C”) is added to the intermediate layer-forming composition M1 with respect to 100 parts by weight of acrylic resin. ) was added to obtain an intermediate layer-forming composition M1′.

[Production Example 5] Preparation of adhesive A1 100 parts by weight of 2-ethylhexyl acrylate, 26 parts by weight of acryloylmorpholine, 18 parts by weight of hydroxyethyl acrylate, 12 parts by weight of 2-methacryloyloxyethyl isocyanate, and azobisisobutyronitrile A mixture obtained by mixing 0.2 parts by weight and 500 parts by weight of ethyl acetate was polymerized at 60° C. for 24 hours in a nitrogen atmosphere to obtain an acrylic polymer A having a weight average molecular weight of 900,000.
To the polymerization liquid (acrylic polymer A content: 100 parts by weight) obtained by the above operation, 7 parts by weight of a photopolymerization initiator (manufactured by IGM Resins, trade name "Omnirad TPO") and an isocyanate cross-linking agent (Nippon Polyurethane Kogyo Co., Ltd., trade name "Coronate C") and 2 parts by weight were added to obtain adhesive A1.

[Production Example 6] Preparation of Adhesive A2 Adhesive A2 was obtained in the same manner as in Production Example 5, except that the amount of the photopolymerization initiator was changed to 3 parts by weight.

[Production Example 7] Preparation of Adhesive A2' Except that the amount of the photopolymerization initiator was 3 parts by weight, and a cross-linking aid (manufactured by ADEKA, trade name "ADEKA POLYETHER EDP-300") was further added. , in the same manner as in Production Example 5 to obtain an adhesive A2'.

[Production Example 8] Preparation of adhesive B1 100 parts by weight of butyl acrylate, 78 parts by weight of ethyl acrylate, 40 parts by weight of hydroxyethyl acrylate, 44 parts by weight of 2-methacryloyloxyethyl isocyanate, and 0 parts by weight of azobisisobutyronitrile A mixture obtained by mixing 2 parts by weight and 500 parts by weight of ethyl acetate was polymerized at 60° C. for 24 hours in a nitrogen atmosphere to obtain an acrylic polymer B having a weight average molecular weight of 500,000.
To the polymerization liquid (acrylic polymer B content: 100 parts by weight) obtained by the above operation, 3 parts by weight of a photopolymerization initiator (manufactured by IGM Resins, trade name "Omnirad TPO") and an isocyanate cross-linking agent (Nippon Polyurethane Kogyo Co., Ltd., trade name "Coronate C") and 2.5 parts by weight were added to obtain adhesive B1.

[Production Example 9] Preparation of Adhesive B2 Adhesive B2 was obtained in the same manner as in Production Example 8, except that the amount of the cross-linking agent was changed to 0.2 parts by weight.

[Example 1]
A polyethylene terephthalate base material (manufactured by Toray Industries, Inc., product name "S105 #50", thickness: 50 μm) as the first base material, and a polyethylene base material (manufactured by Futamura Chemical Co., Ltd., product name "LL") as the second base material -XMTN #50", thickness: 50 μm) were laminated via an adhesive (thickness: 2 μm).
Next, the intermediate layer-forming composition M1 was applied onto the first substrate to form an intermediate layer having a thickness of 28 μm. After that, the adhesive A1 was applied on the intermediate layer to form an adhesive layer with a thickness of 5 μm.
Backgrind Tape A was obtained as described above. The obtained back grind tape A was subjected to the above evaluation. Table 1 shows the results.

[Example 2]
A back-grind tape B was obtained in the same manner as in Example 1, except that the intermediate layer-forming composition M2 was used instead of the intermediate layer-forming composition M1 to form an intermediate layer (thickness: 28 μm). . The obtained back grind tape B was subjected to the above evaluation. Table 1 shows the results.

[Example 3]
A back grind tape C was obtained in the same manner as in Example 1, except that the thickness of the intermediate layer was 18 μm and the adhesive layer (thickness: 5 μm) was formed using the adhesive A2 instead of the adhesive A1. rice field. The obtained back grind tape C was subjected to the above evaluation. Table 1 shows the results.

[Example 4]
The intermediate layer-forming composition M3 was used instead of the intermediate layer-forming composition M1, the thickness of the intermediate layer was 18 μm, and the pressure-sensitive adhesive A2′ was used instead of the pressure-sensitive adhesive A1. A back grind tape D was obtained in the same manner as in Example 1, except that a layer (thickness: 5 μm) was formed. The obtained back grind tape D was subjected to the above evaluation. Table 1 shows the results.

[Example 5]
An intermediate layer-forming composition M1 was applied onto a polyethylene terephthalate substrate (manufactured by Toray Industries, Inc., product name “S105 #50”, thickness: 50 μm) as a first substrate to form an intermediate layer having a thickness of 25 μm. formed. After that, the adhesive A1 was applied on the intermediate layer to form an adhesive layer with a thickness of 5 μm.
A back grind tape E was obtained as described above. The obtained back grind tape E was subjected to the above evaluation. Table 1 shows the results.

[Example 6]
A back grind tape F was obtained in the same manner as in Example 5, except that the adhesive A2 was used instead of the adhesive A1. The obtained back grind tape F was subjected to the above evaluation. Table 1 shows the results.

[Comparative Example 1]
A polyethylene terephthalate base material (manufactured by Toray Industries, Inc., trade name "S105 #50", thickness: 50 µm) was coated with the pressure-sensitive adhesive A2 to form a pressure-sensitive adhesive layer with a thickness of 30 µm.
A back grind tape G was obtained as described above. The obtained back grind tape G was subjected to the above evaluation. Table 1 shows the results.

[Comparative Example 2]
A back grind tape H was obtained in the same manner as in Comparative Example 1, except that the adhesive B1 was used instead of the adhesive A2. The back grind tape H was subjected to the above evaluation. Table 1 shows the results.

[Comparative Example 3]
A back grind tape J was obtained in the same manner as in Comparative Example 1, except that the adhesive B2 was used instead of the adhesive A2. The back grind tape J was subjected to the above evaluation. Table 1 shows the results.

[Comparative Example 4]
An intermediate layer forming composition M1′ was applied onto a polyethylene terephthalate substrate (manufactured by Toray Industries, Inc., product name “S105 #50”, thickness: 50 μm) as a first substrate to form an intermediate layer having a thickness of 28 μm. formed. After that, the adhesive A2 was applied on the intermediate layer to form an adhesive layer having a thickness of 5 μm.
Backgrind Tape K was obtained as described above. The obtained back grind tape K was subjected to the above evaluation. Table 1 shows the results.

[Comparative Example 5]
An intermediate layer forming composition M4 containing an acrylic urethane resin is applied onto a polyethylene terephthalate substrate (manufactured by Toray Industries, Inc., product name “Lumirror ES10#75”, thickness: 75 μm) as a first substrate, and the thickness is An intermediate layer of 75 μm was formed. After that, the adhesive B2 was applied on the intermediate layer to form an adhesive layer having a thickness of 50 μm. The intermediate layer-forming composition M4 was prepared as follows.
A back grind tape L was obtained as described above. The obtained back grind tape L was subjected to the above evaluation. Table 1 shows the results.
<Preparation of intermediate layer forming composition M4>
70 parts by weight of polytetramethylene ether glycol, 50 parts by weight of tertiary butyl acrylate, 30 parts by weight of acrylic acid, 20 parts by weight of butyl acrylate, and an isocyanate compound (manufactured by Mitsui Chemicals, Inc., trade name "Takenate 500") 25 A mixture obtained by mixing parts by weight, 0.1 parts by weight of azobisisobutyronitrile, and 100 parts by weight of ethyl acetate is polymerized at 60° C. for 6 hours under a nitrogen atmosphere to produce an acrylic urethane resin. A polymerization liquid was obtained.
5 parts by weight of a cross-linking agent (trimethylolpropane triacrylate) was added to 100 parts by weight of the acrylic urethane resin to obtain an intermediate layer forming composition M4.

REFERENCE SIGNS LIST 10 adhesive layer 20 intermediate layer 31 first substrate 32 second substrate 100 back grind tape

Claims (9)

An adhesive layer, an intermediate layer, and a first base material are provided in this order,
The intermediate layer is placed directly on the first substrate, and the adhesive layer is placed directly on the intermediate layer,
the material constituting the intermediate layer is a non-crosslinked acrylic resin having a carboxyl group;
The initial adhesive strength when the adhesive layer is attached to the Si mirror wafer is 1 N/20 mm to 30 N/20 mm.
back grind tape. further comprising a second substrate;
the second substrate is positioned on the opposite side of the first substrate from the intermediate layer;
The back grind tape according to claim 1. 3. The backgrinding tape of claim 1 or 2, wherein the first substrate is composed of polyethylene terephthalate. 4. The back grinding tape according to claim 2, wherein said second base material is made of polyolefin resin. 5. The back grinding tape according to claim 1, wherein the pressure-sensitive adhesive layer has a thickness of 1 μm to 50 μm. 6. The back grinding tape according to claim 1, wherein the intermediate layer has a thickness of 5 μm to 50 μm. The back grinding tape according to any one of claims 1 to 6, wherein the adhesive layer has a storage modulus E' at 23°C of 15 MPa to 200 MPa. 8. The back grinding tape according to claim 1, wherein the adhesive layer has a tensile modulus at 23° C. of 0.01 MPa to 2 MPa. 9. The back grind tape according to any one of claims 1 to 8 , which is used when back-grinding a stealth diced semiconductor wafer.

Images