KR102647149B1 - Backgrind tape - Google Patents

Abstract

This is a backgrind tape used in the backgrind process performed after dicing, and provides a backgrind tape that prevents chip dropping that may occur during backgrinding.
The backgrind tape of the present invention includes an adhesive layer, an intermediate layer, and a first base material in this order, and the material constituting the intermediate layer is an acrylic resin that has a carboxyl group and is not crosslinked, and the adhesive layer is The initial adhesive force when adhered to a Si mirror wafer is 1N/20mm to 30N/20mm.

Description

Backgrind tape {BACKGRIND TAPE}

The present invention relates to backgrind tape. More specifically, it relates to a backgrind tape that is suitably used in the backgrind process performed after the dicing process.

A work (e.g., semiconductor wafer), which is an assembly of electronic components, is manufactured into a large diameter, cut and separated into element pieces (diced), and then transferred to the mounting process again. In this dicing process, the work is cut into small pieces. In order to fix the work after dicing, dicing is usually performed after attaching an adhesive tape (dicing tape) to the work (for example, patent document 1). As one of the dicing methods, a method of dicing a work using a laser beam is known. As such a dicing method, a method of focusing laser light on the surface of a work, forming grooves on the surface of the work, and then cutting the work is widely used. Meanwhile, in recent years, stealth dicing has also been proposed in which laser light is concentrated inside the workpiece, the workpiece is modified at that location, and then the workpiece is cut.

Additionally, usually in the processing of a semiconductor wafer, the back surface is ground to a predetermined thickness (for example, 100 μm to 600 μm) (backgrind process). Conventionally, after forming a pattern on the surface of a semiconductor wafer, the surface is fixed to a backgrind tape to perform backside grinding (backgrinding), and then a dicing process is performed. Meanwhile, in recent years, in order to increase the usefulness of the stealth dicing, a technique of performing a backgrind process by fixing the surface to a backgrind tape after performing stealth dicing has been studied.

Japanese Patent Publication No. 2003-007646

As described above, if dicing is performed before the backgrind process, a new problem arises in that, during backgrinding, small pieces of chips interfere with each other and chip dropping occurs.

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

The backgrind tape of the present invention includes an adhesive layer, an intermediate layer, and a first base material in this order, and the material constituting the intermediate layer is an acrylic resin that has a carboxyl group and is not crosslinked, and the adhesive layer is The initial adhesive force when adhered to a Si mirror wafer is 1N/20mm to 30N/20mm.

In one embodiment, the backgrind tape further includes a second substrate, and the second substrate is disposed on the opposite side to the intermediate layer of the first substrate.

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 thickness of the adhesive layer is 1 μm to 50 μm.

In one embodiment, the thickness of the intermediate layer is 5 μm to 50 μm.

In one embodiment, the backgrind tape is used when grinding the backside of a stealth diced semiconductor wafer.

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

1 is a schematic cross-sectional view of a backgrind tape according to one embodiment of the present invention.
Figure 2 is a schematic cross-sectional view of a backgrind tape according to another embodiment of the present invention.

A. Overview of the background tape

1 is a schematic cross-sectional view of a backgrind tape according to one embodiment of the present invention. The backgrind tape 100 according to this embodiment includes an adhesive layer 10, an intermediate layer 20, and a first base material 31. Although not shown, the backgrind tape of the present invention may be provided with a release liner on the outside of the adhesive layer (not shown) for the purpose of protecting the adhesive surface during use. In addition, the backgrind tape may further include any suitable other layer as long as the effect of the present invention is obtained. Preferably, the intermediate layer is disposed directly on the first substrate. Additionally, preferably the adhesive layer is disposed directly on the intermediate layer.

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

In the present invention, a backgrind tape used in a backgrind process performed after dicing is formed by combining an adhesive layer and an intermediate layer, and uses an acrylic resin that has a carboxyl group and is not crosslinked as the material constituting the intermediate layer. In addition, backgrind tape can be provided to prevent chip dropping that may occur during backgrinding. The backgrind tape of the present invention configured as described above has the characteristics of being difficult to deform in response to an external force in the plane direction, and even if deformed, it is difficult to return to its original shape afterwards. By using such a backgrind tape, backgrinding can be performed by preventing small pieces of chips from excessively interfering with each other after dicing and preventing problems such as the chips falling off. The backgrind tape of the present invention is particularly useful for semiconductor wafer processing, including stealth dicing.

Figure 2 is a schematic cross-sectional view of a backgrind tape according to another embodiment of the present invention. The backgrind tape 200 according to this embodiment has a two-layer structure and further includes a second base material 32. The second substrate 32 is disposed on the opposite side to the intermediate layer 20 of the first substrate 31. That is, the backgrind tape 200 includes an adhesive layer 10, an intermediate layer 20, a first substrate 31, and a second substrate 32 in this order. Preferably, as the second substrate, a substrate that is softer (eg, has a lower elastic modulus) than the first substrate is used. The backgrind tape according to this embodiment can more effectively prevent problems such as chip dropping during backgrinding. Semiconductor wafer processing including stealth dicing generates cracks (so-called BHC) extending from the affected layer formed by laser light to the wafer surface, thereby miniaturizing the semiconductor wafer. However, an embodiment in which the cracks are generated before backgrinding is Of course, even in embodiments where processing becomes more difficult, that is, embodiments in which the cracks occur during backgrinding, problems such as chip dropping can be prevented. Additionally, the base material may have a structure of three or more layers.

The initial adhesive force when the adhesive layer of the backgrind tape of the present invention is adhered to a Si mirror wafer is preferably 1 N/20 mm to 30 N/20 mm, and more preferably 2 N/20 mm to 20 N/20 mm. , more preferably 3N/20mm to 15N/20mm, and particularly preferably 4N/20mm to 10N/20mm. Within this range, a backgrind tape capable of well fixing the semiconductor wafer during backgrinding can be obtained. In addition, the backgrind tape of the present invention can be made into a tape whose adhesive strength can be reduced by irradiation of active energy rays (for example, ultraviolet rays), but the above-mentioned “initial adhesive strength” refers to the irradiation of active energy rays. This refers to the adhesive strength before application. In the present invention, adhesive force is measured according to JIS Z 0237: 2000. Specifically, the adhesive force is measured using a tensile tester (Tensilon, manufactured by Shimadzu Seisakusho) under the conditions of 23°C, peeling speed of 300 mm/min, and peeling angle: 180°.

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

B. Description

B-1. 1st description

As the first substrate, a resin film is preferably used. Resins constituting the resin film include, for example, polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polypropylene (PP), polyimide (PI), polyetherimide (PEI), and polyphenyl. Examples include lene sulfide (PPS), polysulfone (PSF), polyetheretherketone (PEEK), and polyarylate (PAR). Among these, polyester resin is preferred, and polyethylene terephthalate is particularly preferred. By using the first base material comprised of polyethylene terephthalate, it is possible to obtain a backgrind tape that can more preferably prevent problems such as chip dropping during backgrinding.

The tensile modulus of elasticity at 23°C of the first substrate is preferably 50 MPa to 10,000 MPa, and more preferably 100 MPa to 5,000 MPa. The tensile modulus of elasticity of the first base material (and each layer constituting the backgrind tape (described later)) was measured using a tensile tester (“AG-IS” manufactured by SHIMADZU), distance between chucks: 50 mm, tensile speed: It is carried out under the conditions of 300 mm/min and sample width: 10 mm.

The thickness of the first substrate is preferably 25 μm to 200 μm, more preferably 30 μm to 150 μm, further preferably 40 μm to 100 μm, and particularly preferably 40 μm to 80 μm. .

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

B-2. 2nd description

As the second substrate, a resin film is preferably used. Resins constituting the resin film include, for example, polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polypropylene (PP), polyimide (PI), polyetherimide (PEI), and polyphenyl. Examples include lene sulfide (PPS), polysulfone (PSF), polyetheretherketone (PEEK), and polyarylate (PAR). Among these, polyolefin resin is preferred.

In one embodiment, the second base material contains polyethylene-based resin or 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. In the polyethylene resin, the content ratio of the structural unit derived from ethylene is preferably 80 mol% or more, more preferably 90 mol% or more, and even 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, for example, 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-tetra Decene, 1-hexadecene, 1-octadecene, 1-icosene, etc. can be mentioned.

In one embodiment, a substrate made of polyethylene terephthalate is used as the first substrate, and a substrate made of polyolefin resin (preferably the polyethylene resin or polypropylene resin) is used as the second substrate. use. By using these base materials, problems such as chip dropping during backgrinding can be more preferably prevented.

The tensile modulus of elasticity at 23°C of the second substrate is preferably 50 MPa to 2000 MPa, and more preferably 100 MPa to 1000 MPa.

The tensile modulus of elasticity at 23°C of the second substrate is preferably smaller than the tensile modulus of elasticity of the first substrate at 23°C. The tensile modulus of elasticity at 23°C of the second base material is preferably 0.5% to 100%, more preferably 0.5% or more and less than 100%, relative to the tensile elasticity modulus of the first base material at 23°C, More preferably, it is 1% to 50%.

The thickness of the second substrate is preferably 25 μm to 200 μm, more preferably 30 μm to 150 μm, further preferably 40 μm to 100 μm, and particularly preferably 40 μm to 80 μm. .

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

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

C. Middle layer

The intermediate layer is composed of an acrylic resin that has a carboxyl group and is not crosslinked (for example, epoxy crosslinked). This intermediate layer can be formed from a composition for forming an intermediate layer that contains an acrylic resin having a carboxyl group in the side chain and does not contain a crosslinking compound such as a crosslinking agent that reacts with the carboxyl group to form a crosslinked structure. The acrylic resin constituting the intermediate layer is obtained by polymerizing a monomer component containing an alkyl (meth)acrylate ester and a carboxyl group-containing monomer, and contains a structural unit derived from an alkyl (meth)acrylate ester and a structural unit derived from a carboxyl group-containing monomer (in the side chain). structural units having a carboxyl group). The presence or absence of crosslinking of the acrylic resin can be confirmed by thermal decomposition 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, pentyl (meth)acrylate, ( Isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, (meth)acrylic acid. Isononyl, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, penta (meth)acrylate Alkyl groups such as decyl, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate are straight or branched and have 4 to 20 carbon atoms. (meth)acrylic acid alkyl esters having an alkyl group, etc. Among these, from the viewpoint of adhesion to the adherend and bonding workability, (meth)acrylic acid alkyl esters in which the alkyl group has 5 to 12 carbon atoms are preferable, and more preferably, n-butyl acrylate or 2-ethylhexyl acrylate ( 2EHA). (meth)acrylic acid alkyl esters can be used individually or in combination of two or more types.

In the acrylic resin, the content ratio of the structural unit derived from alkyl (meth)acrylate is preferably 70 parts by weight to 98 parts by weight, more preferably 85 parts by weight to 96 parts by weight, based on 100 parts by weight of the acrylic resin. It is wealth.

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

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, based on 100 parts by weight of the acrylic resin. Particularly preferably, it is 4 to 8 parts by weight. In addition, 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, and more preferably 5 parts by weight to 100 parts by weight of the structural unit derived from the alkyl (meth)acrylate. It is 20 parts by weight, more preferably 5 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 individually or in combination of two or more types.

Hydroxyl group-containing monomers: e.g. 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate hydroxyalkyl (meth)acrylates such as; 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;

Monomers containing cyano groups: for example acrylonitrile, methacrylonitrile;

Keto group-containing monomers: for example, diacetone (meth)acrylamide, diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl aceto acetate, vinyl aceto acetate;

Monomers with rings containing nitrogen atoms: for example N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpipe Razine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(meth)acryloylmorpholine;

Monomers containing alkoxysilyl groups: for example 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3- (Meth)acryloxypropylmethyldiethoxysilane.

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

The weight average molecular weight of the acrylic resin is preferably 200,000 to 3 million, and more preferably 250,000 to 1.5 million. Weight average molecular weight can be measured by GPC (solvent: THF).

The composition for forming the intermediate layer may further contain any appropriate additives. Examples of the additive include plasticizers, tackifiers, anti-aging agents, fillers, colorants, antistatic agents, and surfactants. The above additives may be used individually or in combination of two or more types. When two or more types of additives are used, they may be added one by one, or two or more types of additives may be added simultaneously. The mixing amount of the additive may 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, and still more preferably 15 μm to 30 μm. Within this range, problems such as chip dropping during backgrinding can be more preferably prevented.

The thickness of the intermediate layer is preferably 2 to 20 times, more preferably 3 to 10 times, and even more preferably 3 to 7 times the thickness of the adhesive layer. If the intermediate layer and the adhesive layer are configured in this thickness relationship, it is possible to obtain a backgrind tape that is difficult to deform in response to external force in the plane direction and is difficult to return to its original shape after deformation.

The storage modulus E' of the intermediate layer at 23°C is preferably 200 MPa or less, more preferably 30 MPa to 180 MPa, and still more preferably 50 MPa to 160 MPa. Within this range, a backgrind tape with particularly excellent followability to uneven surfaces can be obtained. The storage modulus E' can be measured by a nano-indentation method. The measurement conditions are as follows.

(Measurement device and measurement conditions)

Apparatus: Hysitron Inc. Manufacturing Tribo Indenter

Indenter used: Berkovich (triangular pyramid type)

Measurement method: single indentation measurement

Measurement temperature: 25℃

Indentation depth setting: approximately 300㎚

Indentation speed: approximately 10㎚/sec

Frequency: 100Hz

Measurement atmosphere: in air

Sample size: approximately 1 cm × approximately 1 cm

The tensile modulus of elasticity of the intermediate layer at 23°C is preferably 0.05 MPa to 10 MPa, more preferably 0.1 MPa to 5 MPa, and still more preferably 0.2 MPa to 3 MPa. Within this range, in addition to employing a specific material as the material constituting the intermediate layer, problems such as chip dropping during backgrinding can be more preferably prevented.

D. Adhesive layer

The adhesive layer may be made of any suitable adhesive. Examples of the adhesive include acrylic adhesive, rubber adhesive, silicone adhesive, and polyvinyl ether adhesive. The adhesive may be a curing adhesive such as a thermosetting adhesive or an active energy ray curing adhesive, or may be a pressure sensitive adhesive. Preferably a curable adhesive is used. By using a curable adhesive, it is possible to obtain a backgrind tape that secures the semiconductor wafer well during backgrinding and can then be easily peeled off by curing the adhesive layer when peeling is necessary.

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

The acrylic adhesive contains an acrylic polymer as a base polymer. The acrylic polymer may have structural units derived from (meth)acrylic acid alkyl ester. Examples of the (meth)acrylic acid alkyl esters include n-butyl (meth)acrylate, isobutyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, ( Isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, (meth)acrylic acid. Isononyl, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, penta (meth)acrylate Alkyl groups such as decyl, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, and eicosyl (meth)acrylate are straight or branched and have 4 to 20 carbon atoms. (meth)acrylic acid alkyl esters having an alkyl group, etc. Among these, from the viewpoint of adhesion to the adherend and bonding workability, (meth)acrylic acid alkyl esters in which the alkyl group has 5 to 12 carbon atoms are preferable, and more preferably, n-butyl acrylate or 2-ethylhexyl acrylate ( 2EHA). (meth)acrylic acid alkyl esters can be used individually or in combination of two or more types.

The acrylic polymer 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 individually or in combination of two or more types.

Carboxyl group-containing monomers and their anhydrides: for example, 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, and their anhydrides (maleic anhydride, itaconic anhydride, etc.);

Hydroxyl group-containing monomers: e.g. 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate hydroxyalkyl (meth)acrylates such as; 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;

Monomers containing cyano groups: for example acrylonitrile, methacrylonitrile;

Keto group-containing monomers: for example, diacetone (meth)acrylamide, diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl aceto acetate, vinyl aceto acetate;

Monomers with rings containing nitrogen atoms: for example N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpipe Razine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(meth)acryloylmorpholine;

Monomers containing alkoxysilyl groups: for example 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3- (meth)acryloxypropylmethyldiethoxysilane;

Isocyanate group-containing monomers: (meth)acryloylisocyanate, 2-(meth)acryloyloxyethylisocyanate, m-isopropenyl-α,α-dimethylbenzylisocyanate.

In the acrylic polymer, the content ratio of the 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, and even more preferably 5 parts by weight, based on 100 parts by weight of the acrylic polymer. It ranges from 30 parts by weight to 30 parts by weight.

The weight average molecular weight of the acrylic polymer is preferably 200,000 to 3 million, and more preferably 250,000 to 1.5 million.

The adhesive may further contain any appropriate additives. Examples of the additive include a photopolymerization initiator, crosslinking agent, plasticizer, tackifier, anti-aging agent, filler, colorant, antistatic agent, surfactant, etc. The above additives may be used individually or in combination of two or more types. When two or more types of additives are used, they may be added one by one, or two or more types of additives may be added simultaneously. The mixing amount of the additive may be set to any appropriate amount.

In one embodiment, the adhesive further contains a photopolymerization initiator. As the photopolymerization initiator, any suitable initiator can be used. Examples of the photopolymerization initiator include acylphosphine oxide-based photoinitiators such as ethyl 2,4,6-trimethylbenzylphenylphosphinate and (2,4,6-trimethylbenzoyl)-phenylphosphine oxide; 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone, α-hydroxy-α,α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, 1 -α-ketol-based compounds such as hydroxycyclohexylphenyl ketone; Methoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane Acetophenone-based compounds such as -1; Benzoin ether-based compounds such as benzoin ethyl ether, benzoin isopropyl ether, and anisoin methyl ether; Ketal-based compounds such as benzyldimethylketal; aromatic sulfonyl chloride-based compounds such as 2-naphthalenesulfonyl chloride; Photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; Benzophenone-based compounds such as benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; Thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone Thioxanthone-based compounds such as acidthone and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; Acylphosphonate etc. are mentioned. Among these, an acylphosphine oxide-based photoinitiator is preferable. 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 to 10 parts by weight, based on 100 parts by weight of the acrylic polymer. It is wealth.

In one embodiment, the adhesive further contains a crosslinking agent. As the crosslinking agent, any suitable crosslinking agent can be used. For example, isocyanate-based crosslinking agents, epoxy-based crosslinking agents, melamine-based crosslinking agents, peroxide-based crosslinking agents, urea-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, carbodiimide-based crosslinking agents, oxazoline-based crosslinking agents, and ajiri. Examples include dine-based crosslinking agents and amine-based crosslinking agents. Only one type of crosslinking agent may be used, or two or more types may be used in combination. Additionally, the amount of crosslinking agent used can be set to any appropriate value depending on the intended use. The amount of the crosslinking agent used is preferably 0.1 parts by weight to 10 parts by weight, more preferably 0.5 parts by weight to 5 parts by weight, and even more preferably 1 part by weight to 3 parts by weight, based on 100 parts by weight of the acrylic polymer. .

In one embodiment, an isocyanate-based crosslinking agent is preferably used. Isocyanate-based crosslinking agents are preferred because they can react with a variety of functional groups. Specific examples of the isocyanate-based crosslinking agent include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate; Alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate; Aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate; Trimethylolpropane/tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Kogyo, brand name “Coronate L”), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Kogyo, brand name “Coronate”) Isocyanate adducts such as "Nate HL") and the isocyanurate form of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Kogyo Co., Ltd., brand name "Coronate HX"); etc. can be mentioned. Preferably, a crosslinking agent having three or more isocyanate groups is used.

The thickness of the adhesive layer is preferably 1 μm to 50 μm, more preferably 1 μm to 25 μm, and even more preferably 1 μm to 5 μm. Within this range, problems such as chip dropping during backgrinding can be more preferably prevented.

The storage modulus E' of the adhesive layer at 23°C is preferably 15 MPa to 200 MPa, more preferably 20 MPa to 150 MPa, and still more preferably 30 MPa to 120 MPa. Within this range, a backgrind tape with particularly excellent followability to uneven surfaces can be obtained.

The tensile elastic modulus of the adhesive layer at 23°C is preferably 0.01 MPa to 2 MPa, more preferably 0.05 MPa to 1 MPa, and even more preferably 0.1 MPa to 0.5 MPa. Within this range, problems such as chip dropping during backgrinding can be more preferably prevented. Additionally, when the pressure-sensitive adhesive layer is 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 suitable method. Backgrind tape, for example, forms an intermediate layer by coating (applying, drying) the composition for forming an intermediate layer on a substrate (first substrate), and then applying (applying, drying) the adhesive on the intermediate layer to form an adhesive. It can be obtained by forming a layer. As the coating method, various methods such as bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roll coating, lip coating, die coating, dip coating, offset printing, flexo printing, and screen printing can be adopted. Additionally, a method of forming each of the adhesive layer and the intermediate layer separately on a release liner and then transferring and bonding them may be adopted.

[Example]

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to these examples. The test and evaluation methods in the examples are as follows. In addition, unless otherwise specified, “part” and “%” are based on weight.

(1) Adhesion

The backgrind tape was cut into a rectangle with a width of 20 mm to produce a sample.

For the above sample, a 180° peel test was performed under the following conditions in accordance with JIS Z 0237 to measure the adhesive force of the backgrind tape.

<180° peel test>

Adhere: Si mirror wafer

Number of repeat tests: 3

Temperature: 23℃

Peeling angle: 180 degrees

Peeling speed: 300㎜/min

Initial length (chuck spacing): 150 mm

(2) Crack (chip falling) evaluation

A backgrind tape is adhered to one side of a 12-inch Si mirror wafer (thickness: 775 μm) under the following conditions, and then stealth dicing is performed from the side opposite to the adhesive side of the backgrind tape under the following conditions, With the intention of obtaining 680 small pieces of 8 mm x 12 mm, a modified layer was formed inside the mirror wafer.

Next, backgrinding was performed under the following conditions so that the thickness of the mirror wafer was 25 μm.

Next, by in-line conveyance, the mirror wafer after backgrinding was mounted on a dicing tape (manufactured by Nitto Denko, brand name "NLS-516P") and a ring frame.

Afterwards, the surface of the mirror wafer was observed through an optical microscope (×200) through the dicing tape to confirm the presence or absence of cracks, and the ratio of the number of cracks (number of small pieces with cracks) to the total number of small pieces (680). Accordingly, crack evaluation was performed.

<Stealth dicing conditions>

Device: manufactured by Disco, DFL7361 SDE06

Processing conditions: BHC, Non BHC

<Conditions for attaching backgrind tape>

Device: Nitto Seiki DR-3000III

Pressure: 0.3 MPa

Temperature: Room temperature

Speed: 10㎜/min

<Background conditions>

Device: DGP8761 DFM2800 inline grinder manufactured by Disco

After thinning with Z1 (#360) and Z2 (#2000), GDP (gettering DP treatment) was performed.

(3) Storage modulus

The storage elastic modulus E' of the middle layer and the adhesive layer was measured under the following conditions by the nano-indentation method.

<Measurement of storage modulus E'>

Apparatus: Hysitron Inc. Manufacturing Tribo Indenter

Indenter used: Berkovich (triangular pyramid type)

Measurement method: single indentation measurement

Measurement temperature: 23℃

Indentation depth setting: approximately 300㎚

Indentation speed: approximately 10㎚/sec

Frequency: 100Hz

Measurement atmosphere: in air

Sample size: approximately 1 cm × approximately 1 cm

[Preparation Example 1] Preparation of composition M1 for forming an intermediate layer

A mixture obtained by mixing 30 parts by weight of 2-ethylhexyl acrylate, 70 parts by weight of methyl acrylate, 10 parts by weight of acrylic acid, 0.1 part by weight of azobisisobutyronitrile, and 100 parts by weight of ethyl acetate was placed under a nitrogen atmosphere. Polymerization was performed at 60°C for 6 hours to obtain acrylic resin M1 with a weight average molecular weight of 500,000.

The polymerization liquid obtained through the above operation was used as composition M1 for forming an intermediate layer.

[Preparation Example 2] Preparation of composition M2 for forming an intermediate layer

A mixture obtained by mixing 50 parts by weight of butylacrylate, 50 parts by weight of ethyl acrylate, 5 parts by weight of acrylic acid, 0.1 part by weight of azobisisobutyronitrile, and 100 parts by weight of ethyl acetate was heated at 60°C under a nitrogen atmosphere. After polymerization for 6 hours, acrylic resin M2 with a weight average molecular weight of 650,000 was obtained.

The polymerization solution obtained through the above operation was used as composition M2 for forming an intermediate layer.

[Preparation Example 3] Preparation of composition M3 for forming an intermediate layer

1 part by weight of an adduct of trimethylolpropane/tolylene diisocyanate (manufactured by Nippon Polyurethane Industries, brand name “Coronate L”), and polyether polyol (manufactured by ADEKA, brand name “Adeka Polyether EDP-300”) 0.05 parts by weight were mixed, and a composition containing the reactant produced by reacting these compounds was obtained.

1.05 parts by weight of the obtained composition was added to the composition M1 for forming an intermediate layer (acrylic resin M1 content of 100 parts by weight) prepared in Production Example 1, to prepare a composition M3 for forming an intermediate layer.

Additionally, the above reactant does not crosslink the acrylic resin.

[Preparation Example 4] Preparation of composition M1' for forming an intermediate layer

To the composition M1 for forming an intermediate layer, 1 part by weight of an epoxy-based crosslinking agent (manufactured by Mitsubishi Gas Corporation, brand name “Tetrad C”) was added to 100 parts by weight of acrylic resin, thereby obtaining composition M1' for forming an intermediate layer.

[Preparation Example 5] Preparation of adhesive A1

100 parts by weight of 2ethylhexyl acrylate, 26 parts by weight of acryloylmorpholine, 18 parts by weight of hydroxyethyl acrylate, 12 parts by weight of 2-methacryloyloxyethyl isocyanate, and azobisisobutyronitrile The mixture obtained by mixing 0.2 parts by weight with 500 parts by weight of ethyl acetate was polymerized at 60°C for 24 hours in a nitrogen atmosphere to obtain acrylic polymer A with a weight average molecular weight of 900,000.

To the polymerization solution obtained through the above operation (acrylic polymer A content: 100 parts by weight), 7 parts by weight of a photopolymerization initiator (manufactured by IGM Resines, brand name "OmniradTPO") and an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Kogyo Co., Ltd., brand name) 2 parts by weight of “Coronate C”) was added to obtain adhesive A1.

[Preparation Example 6] Preparation of adhesive A2

Adhesive A2 was obtained in the same manner as in Production Example 5, except that the compounding amount of the photopolymerization initiator was 3 parts by weight.

[Preparation Example 7] 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 set to 3 parts by weight and a crosslinking aid (manufactured by ADEKA, brand name "Adeka Polyether EDP-300") was further added.

[Preparation Example 8] Preparation of adhesive B1

100 parts by weight of butylacrylate, 78 parts by weight of ethyl acrylate, 40 parts by weight of hydroxyethyl acrylate, 44 parts by weight of 2-methacryloyloxyethyl isocyanate, and 0.2 parts by weight of azobisisobutyronitrile , and 500 parts by weight of ethyl acetate were polymerized at 60°C for 24 hours in a nitrogen atmosphere to obtain acrylic polymer B with a weight average molecular weight of 500,000.

To the polymerization solution (acrylic polymer B content: 100 parts by weight) obtained by the above operation, 3 parts by weight of a photopolymerization initiator (manufactured by IGM Resines, brand name "OmniradTPO") and an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Kogyo Co., Ltd., brand name) 2.5 parts by weight of “Coronate C”) was added to obtain adhesive B1.

[Preparation Example 9] Preparation of adhesive B2

Adhesive B2 was obtained in the same manner as in Production Example 8, except that the crosslinking agent was added to 0.2 parts by weight.

[Example 1]

A polyethylene terephthalate substrate as the first substrate (manufactured by Toray Industries, brand name “S105 #50”, thickness: 50 μm), and a polyethylene substrate as a second substrate (manufactured by Futamura Chemical Company, brand name “LL-XMTN #50”, thickness: : 50㎛) was laminated through an adhesive (thickness: 2㎛).

Next, the composition M1 for intermediate layer formation was applied on the first substrate to form an intermediate layer with a thickness of 28 μm. After that, adhesive A1 was applied on the middle layer to form an adhesive layer with a thickness of 5 μm.

As described above, backgrind tape A was obtained. The obtained backgrind tape A was subjected to the above evaluation. The results are shown in Table 1.

[Example 2]

Backgrind tape B was obtained in the same manner as in Example 1, except that the intermediate layer (thickness: 28 μm) was formed using the intermediate layer forming composition M2 instead of the intermediate layer forming composition M1. The obtained backgrind tape B was subjected to the above evaluation. The results are shown in Table 1.

[Example 3]

Backgrind tape C was obtained in the same manner as in Example 1, except that the thickness of the middle layer was 18 µm and the adhesive layer (thickness: 5 µm) was formed using adhesive A2 instead of adhesive A1. The obtained backgrind tape C was subjected to the above evaluation. The results are shown in Table 1.

[Example 4]

An adhesive layer (thickness: 5 μm) was formed using composition M3 for intermediate layer formation instead of composition M1, the thickness of the intermediate layer was set to 18 ㎛, and adhesive A2' was used instead of adhesive A1. Other than that, backgrind tape D was obtained in the same manner as in Example 1. The obtained backgrind tape D was subjected to the above evaluation. The results are shown in Table 1.

[Example 5]

Composition M1 for forming an intermediate layer was coated on a polyethylene terephthalate substrate (manufactured by Toray Industries, Ltd., brand name "S105 #50", thickness: 50 μm) as the first substrate, to form an intermediate layer with a thickness of 25 μm. After that, adhesive A1 was applied on the middle layer to form an adhesive layer with a thickness of 5 μm.

As described above, backgrind tape E was obtained. The obtained backgrind tape E was subjected to the above evaluation. The results are shown in Table 1.

[Example 6]

Backgrind tape F was obtained in the same manner as in Example 5, except that adhesive A2 was used instead of adhesive A1. The obtained backgrind tape F was subjected to the above evaluation. The results are shown in Table 1.

[Comparative Example 1]

Adhesive A2 was applied on a polyethylene terephthalate substrate (manufactured by Toray Industries, Ltd., brand name "S105 #50", thickness: 50 μm) as the first substrate, to form an adhesive layer with a thickness of 30 μm.

As described above, backgrind tape G was obtained. The obtained backgrind tape G was subjected to the above evaluation. The results are shown in Table 1.

[Comparative Example 2]

Backgrind tape H was obtained in the same manner as in Comparative Example 1, except that adhesive B1 was used instead of adhesive A2. Backgrind tape H was submitted to the above evaluation. The results are shown in Table 1.

[Comparative Example 3]

Backgrind tape J was obtained in the same manner as in Comparative Example 1, except that adhesive B2 was used instead of adhesive A2. Backgrind Tape J was provided for the above evaluation. The results are shown in Table 1.

[Comparative Example 4]

Composition M1' for forming an intermediate layer was coated on a polyethylene terephthalate substrate (manufactured by Toray Industries, Ltd., brand name "S105 #50", thickness: 50 μm) as the first substrate, to form an intermediate layer with a thickness of 28 μm. After that, adhesive A2 was applied on the middle layer to form an adhesive layer with a thickness of 5 μm.

As described above, backgrind tape K was obtained. The obtained backgrind tape K was subjected to the above evaluation. The results are shown in Table 1.

[Comparative Example 5]

Composition M4 for forming an intermediate layer containing an acrylic urethane resin was coated on a polyethylene terephthalate substrate (manufactured by Toray Corporation, product name "Lumiror ES10#75", thickness: 75 ㎛) as the first substrate, to form an intermediate layer with a thickness of 75 ㎛. formed. After that, adhesive B2 was applied on the middle layer to form an adhesive layer with a thickness of 50 μm. In addition, the composition M4 for forming the intermediate layer was prepared as follows.

As described above, backgrind tape L was obtained. The obtained backgrind tape L was subjected to the above evaluation. The results are shown in Table 1.

<Preparation of composition M4 for intermediate layer formation>

70 parts by weight of polytetramethylene ether glycol, 50 parts by weight of tert-butylacrylate, 30 parts by weight of acrylic acid, 20 parts by weight of butylacrylate, and an isocyanate-based compound (manufactured by Mitsui Chemicals, brand name “Takenate 500”) The mixture obtained by mixing 25 parts by weight, 0.1 part by weight of azobisisobutyronitrile, and 100 parts by weight of ethyl acetate was polymerized at 60°C for 6 hours in a nitrogen atmosphere to obtain a polymerization solution containing an acrylic urethane resin.

To the polymerization solution, 5 parts by weight of a crosslinking agent (trimethylolpropane triacrylate) was added to 100 parts by weight of acrylic urethane resin, and composition M4 for forming an intermediate layer was obtained.

10: Adhesive layer
20: middle layer
31: first base
32: second base material
100: Backgrind tape

Claims (8)

An adhesive layer, an intermediate layer, and a first substrate are provided in this order,
The intermediate layer is disposed directly on the first substrate, and the adhesive layer is directly disposed on the intermediate layer,
The material constituting the intermediate layer is an acrylic resin that has a carboxyl group and is not crosslinked,
A backgrind tape having an initial adhesive force of 1 N/20 mm to 30 N/20 mm when the adhesive layer is adhered to a Si mirror wafer. According to paragraph 1,
Further comprising a second substrate,
A backgrind tape, wherein the second substrate is disposed on the opposite side to the intermediate layer of the first substrate. According to claim 1 or 2,
A backgrind tape, wherein the first base material is made of polyethylene terephthalate. According to paragraph 2,
A backgrind tape, wherein the second base material is made of polyolefin resin. According to claim 1 or 2,
A backgrind tape wherein the adhesive layer has a thickness of 1 μm to 50 μm. According to claim 1 or 2,
A backgrind tape wherein the thickness of the intermediate layer is 5 μm to 50 μm. According to claim 1 or 2,
The acrylic resin has a structural unit derived from a carboxyl group-containing monomer,
A backgrind tape in which the content ratio of the structural unit derived from the carboxyl group-containing monomer is 2 parts by weight to 30 parts by weight with respect to 100 parts by weight of the acrylic resin. According to claim 1 or 2,
Backgrind tape used for back grinding of stealth diced semiconductor wafers.