TWI818053B - Back grinding tape - Google Patents

Abstract

The present invention provides a back polishing tape used in the back polishing step after cutting, and a back polishing tape that prevents wafer defects that may occur during back polishing. The back polishing tape of the present invention is sequentially provided with an adhesive layer, an intermediate layer and a first base material. The material constituting the intermediate layer is an acrylic resin with carboxyl groups and is not cross-linked. The adhesive layer is adhered to the Si mirror wafer. The initial adhesion force at this time is 1 N/20 mm ~ 30 N/20 mm.

Description

Back grinding tape

The present invention relates to a back grinding belt. More specifically, it relates to a back grinding belt preferably used in the back grinding step performed after the cutting step.

A workpiece (such as a semiconductor wafer), which is an assembly of electronic components, is manufactured with a large diameter, cut and separated (cut) into small component pieces, and then transferred to the assembly step. This cutting step cuts the workpiece into small pieces. In order to fix the cut workpiece, an adhesive tape (cutting tape) is usually pasted on the workpiece before cutting (for example, Patent Document 1). As one of the cutting methods, a method of cutting a workpiece using laser light is known. As this type of cutting method, a method is often used in which the laser light is focused on the surface of the workpiece to form a groove on the surface of the workpiece and then the workpiece is cut. On the other hand, in recent years, stealth cutting has also been proposed in which laser light is focused inside a workpiece to modify the workpiece there and then cut the workpiece.

In addition, generally, during the processing of semiconductor wafers, backside grinding is performed until reaching a specific thickness (for example, 100 μm to 600 μm) (backside grinding step). Previously, after forming a pattern on the surface of a semiconductor wafer, the surface was fixed to a back grinding tape for backgrinding, and then a cutting step was performed. On the other hand, in recent years, in order to improve the usefulness of the above-mentioned invisible cutting, a technology of fixing the surface to a back polishing tape and performing a back polishing step after performing stealth cutting has been studied. [Prior technical literature] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2003-007646

[Problem to be solved by the invention]

As mentioned above, if dicing is performed before the back grinding step, a new problem may arise in which the wafers that have been diced into small pieces during back grinding interfere with each other and cause chip defects.

The problem of the present invention is to provide a back polishing tape used in the back polishing step performed after dicing and to prevent wafer defects that may occur during back polishing. [Technical means to solve problems]

The back polishing tape of the present invention is sequentially provided with an adhesive layer, an intermediate layer and a first base material. The material constituting the intermediate layer is an acrylic resin with carboxyl groups and is not cross-linked. The adhesive layer is adhered to the Si mirror wafer. The initial adhesion force at this time is 1 N/20 mm ~ 30 N/20 mm. In one embodiment, the back polishing tape further includes a second base material, and the second base material is disposed on the side opposite to the intermediate layer of the first base material. In one embodiment, the first base material includes polyethylene terephthalate. In one embodiment, the second base material includes polyolefin-based resin. In one embodiment, the thickness of the adhesive layer ranges from 1 μm to 50 μm. In one embodiment, the thickness of the above-mentioned intermediate layer is 5 μm to 50 μm. In one embodiment, the back polishing tape is used for back grinding a stealth-diced semiconductor wafer. [Effects of the invention]

According to the present invention, it is possible to provide a back polishing tape that prevents wafer defects that may occur during back polishing. The back grinding tape of the present invention is particularly useful as a back grinding tape used in the back grinding step performed after cutting (preferably invisible cutting).

A. Overview of back grinding tape FIG. 1 is a schematic cross-sectional view of a back polishing tape according to one embodiment of the present invention. The back polishing tape 100 of this embodiment includes an adhesive layer 10 , an intermediate layer 20 and a first base material 31 . Although not shown in the figures, the back polishing tape of the present invention may be provided with a release liner (not shown) outside the adhesive layer for the purpose of protecting the adhesive surface until it is used. In addition, the back polishing tape may further include any other appropriate layer as long as the effects of the present invention can be obtained. Preferably, the intermediate layer is directly disposed on the first base material. In addition, it is preferable that the adhesive layer is directly disposed on the middle layer.

The back grinding tape of the present invention can be suitably used to fix the semiconductor wafer when back grinding the diced semiconductor wafer, and can be particularly suitably used when invisible dicing is used as the above-mentioned dicing. Stealth dicing refers to the formation of a modified layer inside the semiconductor wafer through the irradiation of laser light. The semiconductor wafer can be cut using the modified layer as a starting point.

In the present invention, the adhesive layer and the intermediate layer are combined and formed, and an acrylic resin having a carboxyl group and which is not cross-linked is used as the material constituting the intermediate layer, thereby providing an adhesive layer that can be used in the back grinding step after cutting. Back polishing tape, and a back polishing tape that prevents chip defects that may occur during back polishing. The back polishing tape of the present invention configured as described above has the following characteristics: it is not easily deformed by external forces in the surface direction, and it is also difficult to return to its original shape after deformation. If such a back polishing tape is used, it is possible to prevent the wafers that have been cut into small pieces from excessive interference with each other, and to prevent the wafer from being damaged or other unfavorable situations such as back polishing. The back grinding 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 back polishing tape according to another embodiment of the present invention. The back polishing tape 200 of this embodiment has a two-layer base material and further includes a second base material 32 . The second base material 32 is disposed on the side of the first base material 31 opposite to the intermediate layer 20 . That is, the back polishing tape 200 includes the adhesive layer 10 , the intermediate layer 20 , the first base material 31 and the second base material 32 in this order. As the second base material, it is preferable to use a base material that is softer (for example, has a lower elastic modulus) than the first base material. The back polishing tape of this embodiment can better prevent disadvantageous situations such as chip defects during back polishing. Semiconductor wafer processing including stealth dicing is an implementation that produces cracks (so-called BHC) extending from the modified layer formed by laser light to the wafer surface to break the semiconductor wafer into small pieces before back grinding. Not only the form, but also in the embodiment in which processing is considered to be more difficult, that is, in the embodiment in which cracks are generated during back grinding, it is possible to prevent disadvantageous situations such as wafer defects. Furthermore, the base material may be composed of three or more layers.

When the adhesive layer of the back polishing tape of the present invention is adhered to the Si mirror wafer, the initial adhesion force is preferably 1 N/20 mm～30 N/20 mm, and more preferably is 2 N/20 mm～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. If it is within this range, it is possible to obtain a back polishing tape that can favorably fix the semiconductor wafer during back polishing. Furthermore, the back polishing tape of the present invention can be a tape whose adhesive force is reduced due to irradiation of active energy rays (such as ultraviolet rays). The above-mentioned "initial adhesive force" refers to the adhesive force before irradiation of active energy rays. In the present invention, the adhesive force is measured according to JIS Z 0237:2000. Specifically, the adhesive force was measured using a tensile testing machine (TENSILON, manufactured by Shimadzu Corporation) under the conditions of 23°C, peeling speed of 300 mm/min, and peeling angle: 180°.

The thickness of the back polishing tape is preferably 35 μm to 500 μm, more preferably 60 μm to 300 μm, and further preferably 80 μm to 200 μm.

B.Substrate B-1. First base material As the first base material, a resin film is preferably used. Examples of the resin constituting the resin film include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polypropylene (PP), polyimide (PI), and polyether resins. Imine (PEI), polyphenylene sulfide (PPS), polystyrene (PSF), polyetheretherketone (PEEK), polyarylate (PAR), etc. Among them, polyester-based resin is preferred, and polyethylene terephthalate is particularly preferred. If the first base material containing polyethylene terephthalate is used, it is possible to obtain a back polishing tape that can better prevent disadvantages such as wafer defects during back polishing.

The tensile elastic modulus of the above-mentioned 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 polishing tape (to be described later)) was measured using a tensile testing machine (manufactured by Shimadzu Corporation, "AG-IS") at a chuck distance of 50 mm, tensile speed: 300 mm/min, sample width: 10 mm.

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

The above-mentioned first base material may further contain any appropriate additives. 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 As the second base material, a resin film is preferably used. Examples of the resin constituting the resin film include polyester resins such as polyethylene terephthalate (PET), polyolefin resins such as polypropylene (PP), polyimide (PI), and polyether resins. Imine (PEI), polyphenylene sulfide (PPS), polystyrene (PSF), polyetheretherketone (PEEK), polyarylate (PAR), etc. Among them, polyolefin-based resin is preferred.

In one embodiment, the second base material contains polyethylene resin or polypropylene resin. Examples of the polyethylene-based resin include low-density polyethylene, linear polyethylene, medium-density polyethylene, high-density polyethylene, ultra-low-density polyethylene, and the like. In the polyethylene-based resin, the content ratio of the structural units derived from ethylene is preferably 80 mol% or more, more preferably 90 mol% or more, and still more preferably 95 mol% or more. Examples of structural units other than structural units derived from ethylene include structural units derived from monomers that can be copolymerized with ethylene to form a copolymer. For example, propylene, 1-butene, isobutylene, 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-eicosene, etc.

In one embodiment, a base material containing polyethylene terephthalate is used as the first base material, and a base material containing a polyolefin-based resin (preferably the above-mentioned polyethylene-based resin or polypropylene-based resin) is used. material as the second base material. If such base materials are used, adverse situations such as chip defects during back grinding can be better prevented.

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

The tensile elastic modulus of the second base material at 23°C is preferably smaller than the tensile elastic modulus of the first base material at 23°C. The tensile elastic modulus of the second base material at 23°C is preferably 0.5% to 100%, more preferably 0.5% or more relative to the tensile elastic modulus of the first base material at 23°C. Less than 100%, more preferably 1% to 50%.

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

The above-mentioned second base material may further contain any appropriate additives. 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 the substrates is, for example, 2 μm to 10 μm.

C.Middle layer The above-mentioned intermediate layer may be composed of an acrylic resin that has a carboxyl group and is not cross-linked (for example, epoxy cross-linked). Such an intermediate layer can be formed from an intermediate layer-forming composition containing an acrylic resin having a carboxyl group in a side chain and not containing 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 monomer components containing alkyl (meth)acrylate and carboxyl group-containing monomers, and contains structural units derived from alkyl (meth)acrylate and carboxyl group-containing monomers. The structural unit of the body (the structural unit having a carboxyl group in the side chain). Whether the acrylic resin is cross-linked or not can be confirmed by thermal decomposition GC/MS analysis.

Examples of the (meth)acrylic acid alkyl ester include: (meth)acrylic acid n-butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid second butyl ester, (meth)acrylic acid third butyl ester Butyl ester, amyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, (meth)acrylic acid 2 -Ethylhexyl, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate , undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, (meth)acrylic acid Pentadecyl ester, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, Alkyl (meth)acrylate, etc., which have a linear or branched alkyl group with a carbon number of 4 to 20, such as eicosanyl (meth)acrylate. Among these, from the viewpoint of adhesion to the adherend or bonding workability, alkyl (meth)acrylate having an alkyl group with a carbon number of 5 to 12 is preferred, and acrylic acid is more preferred. n-Butyl ester or 2-ethylhexyl acrylate (2EHA). Alkyl (meth)acrylate can be used individually by 1 type or in combination of 2 or more types.

In the above-mentioned acrylic resin, the content ratio of the structural unit derived from the alkyl (meth)acrylate is preferably 70 to 98 parts by weight, and more preferably 85 to 96 parts by weight relative to 100 parts by weight of the acrylic resin. 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; and ethylenically unsaturated monocarboxylic acids such as maleic acid, itaconic acid, and citraconic acid. Dicarboxylic acid, etc. The above-mentioned acrylic resin has a carboxyl group in the side chain, and a back polishing tape having an intermediate layer containing this acrylic resin can prevent wafer defects that may occur during back polishing. Only one type of carboxyl group-containing monomer may be used alone or two or more types may be used in combination.

In the above-mentioned acrylic resin, the proportion of the structural unit derived from the carboxyl group-containing monomer is preferably 2 to 30 parts by weight, and more preferably 4 to 15 parts by weight relative to 100 parts by weight of the acrylic resin. Preferably it is 4 parts by weight to 8 parts by weight. In addition, the content ratio of the structural unit derived from the carboxyl group-containing monomer is preferably 2 to 30 parts by weight, and more preferably 5 parts by weight relative to 100 parts by weight of the structural unit derived from the (meth)acrylic acid alkyl ester. ~20 parts by weight, and more preferably 5-10 parts by weight.

If necessary, the acrylic resin may contain a structural unit derived from another monomer copolymerizable with the alkyl (meth)acrylate. Examples of other monomers include the following monomers. These monomers can be used individually by 1 type or in combination of 2 or more types. Hydroxyl-containing monomers: such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, etc. Hydroxyalkyl (meth)acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol; 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, etc. Ether compounds; Amino-containing monomers: such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate; Cyano-containing monomers: such as acrylonitrile, methacrylonitrile; Ketone-containing monomers: such as diacetone (meth)acrylamide, diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetate acetate, vinyl acetate acetate ; Monomers with nitrogen-containing rings: such as N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-ethylene Piperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(methane base) acryloyl morpholine; Alkoxysilyl-containing monomers: such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltriethoxysilane (Methyl)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane.

In the above-mentioned 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 still more preferably 10 parts by weight or less based on 100 parts by weight of the acrylic resin. .

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. The weight average molecular weight can be measured by GPC (solvent: THF).

The above-mentioned intermediate layer forming composition may further contain any appropriate additives. Examples of the additives include plasticizers, tackifiers, antioxidants, fillers, colorants, antistatic agents, surfactants, and the like. The above-mentioned additives may be used alone or in combination of two or more types. When using two or more types of additives, one type can be added at a time, or two or more types of additives can be added at the same time. The blending amount of the above additives can be set to any appropriate amount.

The thickness of the above-mentioned intermediate layer is preferably 5 μm to 50 μm, more preferably 10 μm to 40 μm, and further preferably 15 μm to 30 μm. If it is within this range, unfavorable situations such as chip defects during back grinding can be better prevented.

The thickness of the above-mentioned intermediate layer is preferably 2 times to 20 times, more preferably 3 times to 10 times, and further preferably 3 times to 7 times relative to the thickness of the above-mentioned adhesive layer. If the intermediate layer and the adhesive layer are formed in such a thickness relationship, it is possible to obtain a back polishing tape that is not easily deformed by external forces in the surface direction and that is not easily restored to its original shape after deformation.

The storage elastic modulus E' of the above-mentioned intermediate layer at 23°C is preferably less than 200 MPa, more preferably 30 MPa to 180 MPa, and further preferably 50 MPa to 160 MPa. If it is within this range, it is possible to obtain a back polishing tape having particularly excellent followability to uneven surfaces. The storage elastic modulus E' can be measured by nanoindentation method. The measurement conditions are as follows. (Measurement device and measurement conditions) Device: Tribo Indenter manufactured by Hysitron Inc. Indenter used: Berkovich (triangular pyramid type) Measuring method: single intrusion measurement Measuring temperature: 25℃ Pressing depth setting: about 300 nm Pressing speed: about 10 nm/sec Frequency: 100 Hz Measuring atmosphere: in air Sample size: about 1 cm × about 1 cm

The tensile elastic modulus of the above-mentioned intermediate layer at 23°C is preferably 0.05 MPa to 10 MPa, more preferably 0.1 MPa to 5 MPa, and further preferably 0.2 MPa to 3 MPa. If it is within this range, it can be combined with the use of specific materials as materials constituting the intermediate layer to better prevent adverse situations such as chip defects during back grinding.

D.Adhesive layer The above-mentioned adhesive layer may contain any suitable adhesive. Examples of the adhesive include acrylic adhesives, rubber adhesives, silicone adhesives, polyvinyl ether adhesives, and the like. The above-mentioned adhesive may be a hardening adhesive such as a heat-hardening adhesive, an active energy ray-hardening adhesive, or a pressure-sensitive adhesive. It is better to use hardening adhesive. If a curable adhesive is used, a back polishing tape can be obtained that can secure the semiconductor wafer well during back polishing and can harden the adhesive layer so that it can be easily peeled off when it needs to be peeled off later.

In one embodiment, an acrylic adhesive is used as the adhesive. It is preferable that the acrylic adhesive is a hardening type.

Acrylic adhesives contain an acrylic polymer as a base polymer. The acrylic polymer may have a structural unit derived from alkyl (meth)acrylate. Examples of the (meth)acrylic acid alkyl ester include: (meth)acrylic acid n-butyl ester, (meth)acrylic acid isobutyl ester, (meth)acrylic acid second butyl ester, (meth)acrylic acid third butyl ester Butyl ester, amyl (meth)acrylate, isopentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, (meth)acrylic acid 2 -Ethylhexyl, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate , undecyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, myristyl (meth)acrylate, (meth)acrylic acid Pentadecyl ester, cetyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, nonadecyl (meth)acrylate, (Meth)acrylic acid alkyl esters such as eicosanyl (meth)acrylate and the like having a linear or branched alkyl group with a carbon number of 4 to 20. Among these, from the viewpoint of adhesion to the adherend or bonding workability, alkyl (meth)acrylate having an alkyl group with a carbon number of 5 to 12 is preferred, and acrylic acid is more preferred. n-Butyl ester or 2-ethylhexyl acrylate (2EHA). Alkyl (meth)acrylate can be used individually by 1 type or in combination of 2 or more types.

If necessary, the acrylic polymer may contain a structural unit derived from another monomer copolymerizable with the alkyl (meth)acrylate. Examples of other monomers include the following monomers. These monomers can be used individually by 1 type or in combination of 2 or more types. Carboxyl-containing monomers and their anhydrides: such as acrylic acid (AA), methacrylic acid (MAA), crotonic acid and other ethylenically unsaturated monocarboxylic acids; maleic acid, itaconic acid, citraconic acid and other ethylenically unsaturated dicarboxylic acids Acids and their anhydrides (maleic anhydride, itaconic anhydride, etc.); Hydroxyl-containing monomers: such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, etc. Hydroxyalkyl (meth)acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol; 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, etc. Ether compounds; Amino-containing monomers: such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate; Epoxy group-containing monomers: such as glycidyl (meth)acrylate, methyl glycidyl (meth)acrylate, and allyl glycidyl ether; Cyano-containing monomers: such as acrylonitrile, methacrylonitrile; Ketone-containing monomers: such as diacetone (meth)acrylamide, diacetone (meth)acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetate acetate, vinyl acetate acetate ; Monomers with nitrogen-containing rings: such as N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-ethylene Piperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinylcaprolactam, N-(methane base) acryloyl morpholine; Alkoxysilyl-containing monomers: such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropyltriethoxysilane Acryloyloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane; Isocyanate group-containing monomers: (meth)acrylyl isocyanate, 2-(meth)acrylyloxyethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate.

In the acrylic polymer, the proportion of the structural units derived from the other monomers is less than 50 parts by weight, more preferably 2 to 40 parts by weight, and still more preferably 5 parts by weight 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 above-mentioned adhesive may further contain any suitable additives. Examples of the additives include photopolymerization initiators, cross-linking agents, plasticizers, tackifiers, antioxidants, fillers, colorants, antistatic agents, surfactants, and the like. The above-mentioned additives may be used alone or in combination of two or more types. When using two or more types of additives, you can add one type at a time, or you can add two or more types of additives at the same time. The blending amount of the above additives can 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: ethyl 2,4,6-trimethylbenzylphenylphosphinate and (2,4,6-trimethylbenzyl)-phenylphosphine oxide. Isocarboxylic phosphine oxide series photoinitiator; 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)one, α-hydroxy-α,α'-dimethylacetophenone , 2-methyl-2-hydroxypropiophenone, 1-hydroxycyclohexylphenylketone and other α-ketool compounds; methoxyacetophenone, 2,2-dimethoxy-2-phenylphenyl Ketones, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropane-1 and other acetophenone compounds; benzoin Benzoin ether compounds such as diethyl ether, benzoin isopropyl ether, anisoin methyl ether and other benzoin ether compounds; ketal compounds such as benzoyl dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalene sulfonyl chloride; 1-benzene Photoactive oxime compounds such as ketone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; benzophenone, benzylbenzoic acid, 3,3'-dimethyl-4- Benzophenone compounds such as methoxybenzophenone; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone Ketones, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone and other thioxanthone compounds; camphorquinone; halogenated ketones; acylphosphine Acid esters, etc. Among them, a acylphosphine oxide photoinitiator is preferred. The usage amount of the photopolymerization initiator is preferably 1 to 20 parts by weight, more preferably 2 to 15 parts by weight, and further preferably 3 to 10 parts by weight based on 100 parts by weight of the acrylic polymer. share.

In one embodiment, the adhesive further contains a cross-linking agent. As the above-mentioned cross-linking agent, any suitable cross-linking agent can be used. Examples include: 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, and metal chelate-based cross-linking agents. Cross-linking agents, metal salt-based cross-linking agents, carbodiimide-based cross-linking agents, oxazoline-based cross-linking agents, aziridine-based cross-linking agents, amine-based cross-linking agents, etc. Only one type of cross-linking agent may be used, or two or more types may be used in combination. Furthermore, the usage amount of the cross-linking agent can be set to any appropriate value according to the intended use. The usage amount of the cross-linking agent is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 5 parts by weight, and further preferably 1 to 3 parts by weight based on 100 parts by weight of the acrylic polymer.

In one embodiment, it is preferable to use an isocyanate cross-linking agent. Isocyanate-based cross-linking agents are preferred because they can react with a variety of functional groups. Specific examples of the isocyanate cross-linking agent include lower aliphatic polyisocyanates such as butyl diisocyanate and hexamethylene diisocyanate; cyclopentyl diisocyanate, cyclohexyl diisocyanate, isophor Alicyclic isocyanates such as ketone diisocyanate; aromatic isocyanates such as 2,4-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate; trimethylolpropane/toluene diisocyanate Isocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE L"), trimethylolpropane/hexamethylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd.) , trade name "CORONATE HL"), isocyanate adducts such as the isocyanurate body of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE HX"); etc. It is preferred to use a cross-linking agent with three or more isocyanate groups.

The thickness of the above-mentioned adhesive layer is preferably 1 μm to 50 μm, more preferably 1 μm to 25 μm, and further preferably 1 μm to 5 μm. If it is within this range, unfavorable situations such as chip defects during back grinding can be better prevented.

The storage elastic modulus E' of the above-mentioned adhesive layer at 23°C is preferably 15 MPa to 200 MPa, more preferably 20 MPa to 150 MPa, and further preferably 30 MPa to 120 MPa. If it is within this range, it is possible to obtain a back polishing tape having particularly excellent followability to uneven surfaces.

The tensile elastic modulus of the above-mentioned adhesive layer at 23°C is preferably 0.01 MPa to 2 MPa, more preferably 0.05 MPa to 1 MPa, and further preferably 0.1 MPa to 0.5 MPa. If it is within this range, unfavorable situations such as chip defects during back grinding can be better prevented. Furthermore, when the adhesive layer is a hardened type, the tensile elastic modulus of the adhesive layer before hardening is preferably within the above range.

E. Manufacturing method of back grinding tape The above-mentioned back grinding tape can be manufactured by any suitable method. The back polishing tape can form an intermediate layer by coating (coating and drying) the above-mentioned intermediate layer forming composition on a base material (first base material), and then coating (coating and drying) the above-mentioned adhesive on the intermediate layer. agent to form an adhesive layer. As the coating method, bar coater coating, air knife coating, gravure coating, gravure reverse coating, reverse roller coating, lip coating, slit coating, dip coating, offset printing, Various methods such as flexographic printing and screen printing. In addition, methods such as forming an adhesive layer and an intermediate layer separately on a release liner and then transferring and laminating them can be used. Example

Hereinafter, the present invention will be specifically described with reference to 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 stated, "parts" and "%" are based on weight.

(1)Adhesion Cut the back polishing tape into strips with a width of 20 mm to prepare samples. For the above samples, according to JIS Z 0237, a 180° peel test was performed under the following conditions to measure the adhesion of the back polishing tape. ＜180° peel test＞ Object to be bonded: Si mirror wafer Number of repeated tests: 3 times Temperature: 23℃ Peeling angle: 180 degrees Peeling speed: 300 mm/min Initial length (chuck spacing): 150 mm (2) Crack (wafer defect) evaluation The back polishing tape is adhered to one side of the 12-inch Si mirror wafer (thickness: 775 μm) under the following conditions. Then, stealth cutting is performed from the side of the back polishing tape opposite to the adhesive surface under the following conditions. , forming a modified layer inside the mirror wafer to obtain 680 small pieces of 8 mm × 12 mm. Then, under the following conditions, back grinding was performed so that the thickness of the mirror wafer was 25 μm. Then, the mirror wafer after back grinding is mounted on a dicing belt (manufactured by Nitto Denko Co., Ltd., trade name "NLS-516P") and a ring frame through inline transport. Then, observe the surface of the mirror wafer with an optical microscope (×200) through the dicing tape to confirm whether cracks have occurred. Based on the ratio of the number of cracks (the number of cracked dies) to the total number of dies (680 pieces), Crack evaluation. ＜Invisible cutting conditions＞ Device: Manufactured by DISCO Corporation, DFL7361 SDE06 Processing conditions: BHC, Non BHC ＜Conditions for attaching back polishing tape＞ Device: Nitto Seiki Co., Ltd. DR-3000III Pressure: 0.3 MPa Temperature: room temperature Speed: 10 mm/min ＜Back Grinding Conditions＞ Device: Manufactured by DISCO Corporation, DGP8761 DFM2800 Inline Grinder After thinning with Z1 (#360) and Z2 (#2000), GDP (degassing DP treatment) is performed (3)Storage elastic modulus The storage elastic modulus E' of the intermediate layer and the adhesive layer was measured using the nanoindentation method under the following conditions. ＜Measurement of storage elastic modulus E'＞ Device: Tribo Indenter manufactured by Hysitron Inc. Indenter used: Berkovich (triangular pyramid type) Measuring method: single intrusion measurement Measuring temperature: 23℃ Pressing depth setting: about 300 nm Pressing speed: about 10 nm/sec Frequency: 100 Hz Measuring atmosphere: in air Sample size: about 1 cm × about 1 cm

[Production Example 1] Preparation of intermediate layer forming composition M1 The 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 parts by weight of azobisisobutyronitrile, and 100 parts by weight of ethyl acetate was placed in a nitrogen atmosphere. Polymerize at 60° C. for 6 hours to obtain acrylic resin M1 with a weight average molecular weight of 500,000. The polymerization liquid obtained by the above-mentioned operation is called the intermediate layer forming composition M1.

[Production Example 2] Preparation of intermediate layer forming composition M2 The mixture obtained by mixing 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 100 parts by weight of ethyl acetate was placed in a nitrogen atmosphere at 60°C. After polymerization for 6 hours, an acrylic resin M2 with a weight average molecular weight of 650,000 was obtained. The polymerization liquid obtained by the above-mentioned operation is called the intermediate layer forming composition M2.

[Production Example 3] Preparation of intermediate layer forming composition M3 Mix 1 part by weight of the adduct of trimethylolpropane/toluene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name "CORONATE L") and polyether polyol (manufactured by ADEKA Co., Ltd., trade name "ADEKA Polyether" EDP-300") 0.05 parts by weight was mixed to obtain a composition containing the reactants generated by the reaction of these compounds. 1.05 parts by weight of the obtained composition was added to the intermediate layer-forming composition M1 prepared in Production Example 1 (acrylic resin M1 content: 100 parts by weight) to prepare an intermediate layer-forming composition M3. In addition, the above-mentioned reactant does not cross-link the acrylic resin.

[Production Example 4] Preparation of intermediate layer forming composition M1' To the above-mentioned intermediate layer forming composition M1, 1 part by weight of an epoxy cross-linking agent (manufactured by Mitsubishi Gas Co., Ltd., trade name "TETRAD C") was added to 100 parts by weight of the acrylic resin to obtain an intermediate layer. Use composition M1'.

[Production Example 5] Preparation of adhesive A1 Mix 100 parts by weight of 2-ethylhexyl acrylate, 26 parts by weight of acrylomorpholine, 18 parts by weight of hydroxyethyl acrylate, 12 parts by weight of 2-methacryloyloxyethyl isocyanate, and azobisisobutyronitrile. The mixture obtained by adding 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 with a weight average molecular weight of 900,000. To the polymerization liquid obtained by the above operation (content of acrylic polymer A: 100 parts by weight), 7 parts by weight of a photopolymerization initiator (manufactured by IGM Resines, trade name "Omnirad TPO") and an isocyanate cross-linking agent ( Manufactured by Japan Polyurethane Industry Co., Ltd., trade name "CORONATE C") 2 parts by weight to obtain adhesive A1.

[Production Example 6] Preparation of adhesive A2 Except that the compounding amount of the photopolymerization initiator was 3 parts by weight, the same procedure as in Production Example 5 was performed to obtain adhesive A2.

[Production Example 7] Preparation of adhesive A2' The compounding amount of the photopolymerization initiator was set to 3 parts by weight, and a cross-linking assistant (manufactured by ADEKA Co., Ltd., trade name "ADEKA Polyether EDP-300") was added. Except for this, the same procedure as in Production Example 5 was performed to obtain Adhesive A2'.

[Production Example 8] Preparation of adhesive B1 Mix 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, 0.2 parts by weight of azobisisobutyronitrile and acetic acid. The mixture obtained by adding 500 parts by weight of ethyl ester was polymerized at 60° C. for 24 hours in a nitrogen atmosphere to obtain an acrylic polymer B with a weight average molecular weight of 500,000. To the polymerization solution obtained by the above operation (acrylic polymer B content: 100 parts by weight), 3 parts by weight of a photopolymerization initiator (manufactured by IGM Resines, trade name "Omnirad TPO") and an isocyanate cross-linking agent ( Manufactured by Japan Polyurethane Industry Co., Ltd., trade name "CORONATE C") 2.5 parts by weight to obtain adhesive B1.

[Production Example 9] Preparation of adhesive B2 Except that the compounding amount of the crosslinking agent was 0.2 parts by weight, the same procedure as in Production Example 8 was performed to obtain adhesive B2.

[Example 1] The polyethylene terephthalate base material (manufactured by Toray Co., Ltd., trade name "S105 #50", thickness: 50 μm) as the first base material and the second base material were bonded via an adhesive (thickness: 2 μm). 2 The base material is a polyethylene material (manufactured by FUTAMURA CHEMICAL Co., Ltd., trade name "LL-XMTN #50", thickness: 50 μm). Next, the intermediate layer forming composition M1 was applied on the first base material to form an intermediate layer with a thickness of 28 μm. Then, apply adhesive A1 on the middle layer to form an adhesive layer with a thickness of 5 μm. Proceeding as described above, back polishing tape A was obtained. The obtained back polishing tape A was used for the above evaluation. The results are shown in Table 1.

[Example 2] 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 same procedure as in Example 1 was performed to obtain a back polishing tape B. The obtained back polishing tape B was used for the above evaluation. The results are shown in Table 1.

[Example 3] The thickness of the intermediate layer was set to 18 μm, and the adhesive layer (thickness: 5 μm) was formed by using adhesive A2 instead of adhesive A1. The procedure was carried out in the same manner as in Example 1 to obtain back polishing tape C. The obtained back polishing tape C was used for the above evaluation. The results are shown in Table 1.

[Example 4] The intermediate layer forming composition M3 is used instead of the intermediate layer forming composition M1, the thickness of the intermediate layer is set to 18 μm, and the adhesive A2' is used instead of the adhesive A1 to form an adhesive layer (thickness: 5 μm), Except for this, the same procedure as in Example 1 was carried out to obtain a back polishing tape D. The obtained back polishing tape D was used for the above evaluation. The results are shown in Table 1.

[Example 5] The intermediate layer forming composition M1 was coated on the polyethylene terephthalate base material (manufactured by Toray Co., Ltd., trade name "S105 #50", thickness: 50 μm) as the first base material to form a thickness of 25 μm intermediate layer. Then, apply adhesive A1 on the middle layer to form an adhesive layer with a thickness of 5 μm. Proceeding as described above, back polishing tape E was obtained. The obtained back polishing tape E was used for the above evaluation. The results are shown in Table 1.

[Example 6] Except having used adhesive A2 instead of adhesive A1, it carried out similarly to Example 5, and obtained the back polishing tape F. The obtained back polishing tape F was used for the above evaluation. The results are shown in Table 1.

[Comparative example 1] Adhesive A2 is coated on the polyethylene terephthalate base material (manufactured by Toray Co., Ltd., trade name "S105 #50", thickness: 50 μm) as the first base material to form an adhesive layer with a thickness of 30 μm. agent layer. Proceed as described above, and obtain the back polishing tape G. The obtained back polishing tape G was used for the above evaluation. The results are shown in Table 1.

[Comparative example 2] Except having used adhesive B1 instead of adhesive A2, it carried out similarly to the comparative example 1, and obtained the back polishing tape H. The back polishing tape H was subjected to the above evaluation. The results are shown in Table 1.

[Comparative example 3] Except having used adhesive B2 instead of adhesive A2, it carried out similarly to the comparative example 1, and obtained the back polishing tape J. Back polishing tape J was used for the above evaluation. The results are shown in Table 1.

[Comparative example 4] The intermediate layer forming composition M1' was coated on the polyethylene terephthalate base material (manufactured by Toray Co., Ltd., trade name "S105 #50", thickness: 50 μm) as the first base material to form The middle layer is 28 μm thick. Then, apply adhesive A2 on the middle layer to form an adhesive layer with a thickness of 5 μm. Proceed as described above, and obtain the back polishing tape K. The obtained back polishing tape K was used for the above evaluation. The results are shown in Table 1.

[Comparative example 5] A polyethylene terephthalate base material (manufactured by Toray Co., Ltd., trade name "Lumirror ES10#75", thickness: 75 μm) as the first base material was coated with an acrylic urethane resin. The intermediate layer forming composition M4 formed an intermediate layer with a thickness of 75 μm. Then, apply adhesive B2 on the middle layer to form an adhesive layer with a thickness of 50 μm. Furthermore, the intermediate layer forming composition M4 is prepared as follows. Proceeding as described above, a back polishing tape L is obtained. The obtained back polishing tape L was used for the above evaluation. The results are shown in Table 1. <Preparation of intermediate layer forming composition M4> 70 parts by weight of polytetramethylene ether glycol, 50 parts by weight of tert-butyl acrylate, 30 parts by weight of acrylic acid, 20 parts by weight of butyl acrylate, and an isocyanate-based compound (manufactured by Mitsui Chemicals Co., Ltd., trade name "TAKENATE 500" 》) 25 parts by weight, 0.1 parts by weight of azobisisobutyronitrile and 100 parts by weight of ethyl acetate, the mixture was polymerized at 60°C for 6 hours under a nitrogen atmosphere to obtain a polymerization containing acrylic urethane resin. liquid. To the above polymerization liquid, 5 parts by weight of a crosslinking agent (trimethylolpropane triacrylate) was added to 100 parts by weight of the acrylic urethane resin to obtain an intermediate layer forming composition M4.

[Table 1]

10: Adhesive layer 20:Middle layer 31: 1st base material 32: 2nd base material 100:Back grinding tape

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

10: Adhesive layer

20:Middle layer

31: 1st base material

100:Back grinding tape

Claims (8)

A back grinding tape, which is provided with an adhesive layer, an intermediate layer and a first base material in order. The material constituting the middle layer is an uncrosslinked acrylic resin with carboxyl groups. The initial adhesion force when the adhesive layer is pasted on the Si mirror wafer is 1 N/20 mm ~ 30 N/20 mm. The back polishing tape of claim 1 further includes a second base material, The second base material is disposed on the side opposite to the intermediate layer of the first base material. The back grinding tape of claim 1 or 2, wherein the first base material includes polyethylene terephthalate. The back polishing tape of claim 2, wherein the second base material contains polyolefin resin. For example, the back polishing tape of claim 1 or 2, wherein the thickness of the adhesive layer is 1 μm to 50 μm. For example, the back polishing tape of claim 1 or 2, wherein the thickness of the above-mentioned intermediate layer is 5 μm to 50 μm. The back grinding tape of claim 1 or 2, wherein the acrylic resin has a structural unit derived from a carboxyl group-containing monomer, The content ratio of the structural unit derived from the carboxyl group-containing monomer is 2 to 30 parts by weight relative to 100 parts by weight of the acrylic resin. For example, the back grinding tape of claim 1 or 2 is used for back grinding semiconductor wafers that have been invisible cut.