JP2002241713A - Sheet for protecting semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems that a gap is sometimes formed between a circuit and a sheet for fixing a semiconductor wafer or chipping or cracking sometimes occurs during polishing of the semiconductor wafer when the sheet for fixing the semiconductor wafer is laminated onto the semiconductor wafer having unevennesses of about 100 μm on the surface thereof. SOLUTION: This sheet for the semiconductor wafer is obtained by providing a cushion layer between a sheetlike support and an adhesive mass layer laminated onto one surface of the support and regulating the dynamic modulus of elasticity of the cushion layer at 10-40 deg.C to 1×10-2 to 5×103 N/cm2, the thickness of the cushion layer to 10-300 μm and the thickness of the adhesive mass layer to 5-150 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor wafer,
The present invention relates to a semiconductor wafer protection sheet that is attached to a surface on which a circuit is formed and protects the circuit when the other surface is polished. In particular, even if the circuit has irregularities of about 100 μm, The present invention relates to a semiconductor wafer protection sheet that does not form a gap between the semiconductor wafer protection sheet and a semiconductor wafer protection sheet and that does not chip or break when polishing a surface of the semiconductor wafer where a circuit is not formed.

[0002]

2. Description of the Related Art A semiconductor wafer protection sheet is attached to a surface of a semiconductor wafer on which circuits are formed, and is used as a semiconductor wafer protection sheet for protecting the circuit when polishing the other surface. An elastic sheet is known in which an elastic sheet is laminated to protect the unevenness of a circuit by deformation of the elastic sheet (for example, JP-A-2000-331968).

[0003]

However, in the semiconductor wafer fixing sheet according to this technique, if the unevenness of the circuit formed on the surface of the semiconductor wafer becomes too large, the elastic sheet cannot be completely deformed, and the circuit and the semiconductor wafer are protected. A gap is generated between the sheet and the sheet. In this gap,
In some cases, polishing debris generated when the back surface of the semiconductor wafer is polished invades and damages the circuit.

Here, it is conceivable to increase the thickness of the elastic sheet in order to protect the circuit. However, if the thickness is simply increased, the elastic sheet itself cannot withstand the stress when polishing the semiconductor wafer, and the semiconductor wafer may vibrate, causing chipping or cracking of the semiconductor wafer.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semiconductor wafer protection sheet which does not form a gap between a circuit and a semiconductor wafer protection sheet, even if a circuit formed on the surface of the semiconductor wafer has irregularities of about 100 μm. It is an object of the present invention to provide a semiconductor wafer protection sheet which does not chip or break when polishing a surface on which the circuit is not formed.

[0006]

Means for Solving the Problems The present inventor has made intensive studies in view of the above, and as a result, has found that a semiconductor wafer protection device having a sheet-like support and an adhesive layer laminated on one surface of the support is provided. in the seat, the cushion layer is provided between the support and the adhesive layer, the dynamic modulus of elasticity at 10 to 40 ° C. of the cushion layer is ^{1 × 10 -2 ~5 × 10 3} N / cm 2, the thickness 10 to 300 μm and the thickness of the pressure-sensitive adhesive layer is 5 to 1 μm.
It has been found that the above problem can be solved by setting the thickness to 50 μm, and the present invention has been completed.

BEST MODE FOR CARRYING OUT THE INVENTION

[0007] The cushion layer in the semiconductor wafer protection sheet according to the present invention is employed for protecting circuits formed on the surface of the semiconductor wafer.

In the cushion layer, when a circuit is pressed against the surface of the cushion layer via the adhesive layer, the cushion layer is crushed by the pressing.
When the cushion layer is crushed, the surface of the cushion layer and the pressure-sensitive adhesive layer have a shape surrounding the circuit, and the circuit can be protected without any gap. Therefore, polishing chips generated when polishing the back surface of the semiconductor wafer do not enter, so that the circuit is not damaged.

If the dynamic elastic modulus of the cushion layer at 10 to 40 ° C. is too large, the cushion layer is not crushed and the semiconductor wafer protection sheet cannot follow the unevenness of the circuit. There will be a gap between them. When cooling water or polishing debris used for polishing a semiconductor wafer enters through this gap,
The semiconductor wafer is chipped or cracked. Moreover, since the dynamic elastic modulus is not cushioning layer is to withstand the stresses at the time of polishing a semiconductor wafer and too small, the semiconductor wafer ends up with or cracked or chipped semiconductor wafer vibrations, 1 × 10 ^{- 2 ~5 × 10 3 N / cm} 2 is good. The dynamic elastic modulus is obtained by measuring the G ′ value of the material constituting the cushion layer, and is a value indicating the ratio of the strain to the stress applied to the material.

On the other hand, if the thickness of the cushion layer is too large, the semiconductor wafer vibrates due to stress when the semiconductor wafer is polished, and the semiconductor wafer is chipped or broken. On the other hand, if it is too thin, it is impossible to protect the surface of the semiconductor wafer from unevenness due to the circuit, and a gap is formed between the circuit and the semiconductor wafer protection sheet. If cooling water or polishing debris used for polishing the semiconductor wafer enters through the gap, the semiconductor wafer may be chipped or cracked.

The cushion layer is formed by laminating a mixture of a base polymer and a curable compound and a curing initiator on one surface of a support, and then curing the composition by irradiating ultraviolet rays or heating to obtain a dynamic elasticity. The rate has been adjusted.

As the base polymer, an acrylic resin,
A synthetic resin obtained by polymerizing a monomer component used for preparing a known pressure-sensitive adhesive, such as a rubber-based elastomer or a styrene-conjugated diene block copolymer, can be used.

Specific examples of the monomer component include a methyl group,
Ethyl, propyl, butyl, 2-ethylhexyl, isooctyl, isononyl, isodecyl, dodecyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, eicoxyl As usual, acrylic acid or methacrylic acid having an alkyl group having 20 or less carbon atoms, itaconic acid, hydroxyethyl acrylate group, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, N-methylolacrylamide, acrylonitrile, Examples include methacrylonitrile, glycidyl acrylate, vinyl acetate, styrene, isoprene, butadiene, isobutylene, and vinyl ether.

The curable compound incorporated in the cushion layer is employed in combination with a curing initiator to increase the dynamic elastic modulus of the entire cushion layer. If the compounding ratio is too small, the portion that is hardened even when irradiated or heated with ultraviolet rays is reduced, so that the dynamic elastic modulus does not improve.If the compounding ratio is too large, the cushion layer does not collapse and the circuit formed on the semiconductor surface is not crushed. Since a gap is formed between the sheet and the semiconductor wafer protection sheet, the amount is preferably 10 to 200 parts by weight, and more preferably 20 to 100 parts by weight, based on 100 parts by weight of the base polymer.

The curable compound is preferably a functional curable compound having two or more functional groups, for example, acrylate compounds, urethane acrylates, urethane acrylate oligomers and / or monomers, epoxy acrylates, polyesters There is a single or mixed system such as acrylate. The curable compound is not particularly limited, but preferably has a molecular weight of 300 to 30,000.

Examples of the acrylate compound include trimethylolpropane triacrylate, tetramethylolmethanetetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate and 1,4- Examples include butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, and oligoester acrylate.

Examples of the urethane acrylate include polyester urethane acrylate, polyether urethane acrylate, tetrafunctional urethane acrylate, and 6-functional urethane acrylate.
There is a functional urethane acrylate.

The urethane acrylate oligomer is a curable compound having at least two carbon-carbon double bonds, for example, a polyol compound of polyester type or polyether type, a polyvalent isocyanate compound,
For example, (2,4-tolylene diisocyanate, 2,6-
Hydroxyl group to a terminal isocyanate urethane prepolymer obtained by reacting tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane 4,4-diisocyanate, etc. Acrylate or methacrylate (for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate,
(Eg, polyethylene glycol methacrylate).

The above epoxy acrylate is synthesized by reacting an epoxy group with acrylic acid or methacrylic acid, and includes bisphenol A type, bisphenol S type, bisphenol F type, epoxy oil type, phenol novo. There are rack type, alicyclic type and the like.

The polyester acrylate is obtained by condensing acrylic acid to an OH group remaining on a polyester skeleton synthesized from a diol, a polyol and a dibasic acid to form an acrylate. For example, phthalic anhydride / propylene oxide diol / acrylic Acid, adipic acid / 1,6
-Hexanediol / acrylic acid, trimellitic acid / diethylene glycol / acrylic acid and the like.

The curing initiator compounded in the cushion layer is
This is adopted to increase the cohesive force of the entire cushion layer by increasing the bonding at the reaction point with the curable compound. Examples of the curing initiator include an ultraviolet curing initiator that starts a reaction by irradiation with ultraviolet light and a heat curing initiator that starts a reaction when heated. If these compounding ratios are too small, curing is slow and workability is inferior, and if too large, unreacted initiator remains and contamination occurs,
0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the base polymer is good.

As the ultraviolet curing initiator, specifically,
Chloroacetophenone, diethoxyacetophenone, hydroxyacetophenone, 1-hydroxycyclohexylphenylketone, α-aminoacetophenone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholine Nopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2
-Hydroxy-2-methylpropan-1-one, mixed photoinitiator, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, allylketone-containing photoinitiator, benzoin, benzoin methyl ether, Benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin ether, benzyl dimethyl ketal, benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate,
4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4 ′
-Methyldiphenyl sulfide, 3,3'-dimethyl-4-methoxybenzophenone, methyl-O-benzoylbenzoate, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxan Son, isopropylthioxanthone, 2, 4
-Dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, α-
Acyl oxime esters, α-acyloxime esters,
Acylphosphine oxide, methylphenylglyoxylate, glyoxyester, 3-ketocoumarin, 2
-Ethylanthraquinone, camphorquinone, benzyl, 9,10-phenanthrenequinone, anthraquinone, dibenzosuberone, 4 ', 4''-diethylisophthalophenone,Michler's ketone, cyclic photoinitiator, tetramethylthiuram Monosulfide, 3,3 ', 4,4'
-Tetra (t-butylperoxycarbonyl) benzophenone and the like. As the above chloroacetophenone,
4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 4-t-butyl-trichloroacetophenone and the like.

The heat curing initiator includes an organic peroxide derivative and an azo-based polymerization initiator. The azo-based polymerization initiator is preferably an organic peroxide derivative because nitrogen is generated during heating. Specific examples of the heat curing initiator include ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxyester, peroxydicarbonate, azobisisobutyronitrile and the like. .

When the above-mentioned ultraviolet curing initiator is used as a curing initiator to be blended in the cushion layer of the present invention, a photoinitiating auxiliary may be blended if necessary. Although the photoinitiator itself is not activated by irradiation with ultraviolet light, the initiation reaction is accelerated by using the ultraviolet light curing initiator alone when used in combination with the ultraviolet light curing initiator, and the curing reaction is made efficient. . Further, if necessary, an amine compound such as triethylamine, tetraethylpentamine, or dimethylaminoether may be used in combination as a polymerization accelerator.

As the photoinitiating auxiliary, there are mainly aliphatic and aromatic amines, specifically, triethanolamine,
Methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michler's ketone, 4,4′-diethylaminophenone, 4,4′-
Diethylaminobenzophenone, ethyl 2-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, 4
-(N-butoxy) ethyl dimethylaminobenzoate, 4-
Isoamyl dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, polymerizable tertiary amine, triethylamine, tetraethylpentaamine, dimethylaminoether, and the like.

In order to start the curing of the ultraviolet-curable compound and the heat-curable compound, it is necessary to irradiate and heat ultraviolet rays, respectively. The timing of irradiating and heating the ultraviolet rays to cure these curable compounds may be not only before lamination of the adhesive but also after lamination of the adhesive depending on the adhesive. The irradiation amount of the ultraviolet rays is preferably in a range of ²⁰ to 500 mJ / cm ² at a frequency of 365 nm, and more preferably in a range of 50 to 150 mJ / cm ² . As the heating temperature, a temperature range of 50 to 150 ° C. is preferable. This is because if the irradiation or heating of the ultraviolet rays is too small, the cohesive strength cannot be improved, and if the irradiation or heating is too large, it takes time and the productivity is deteriorated.

The pressure-sensitive adhesive layer of the semiconductor wafer protection sheet according to the present invention is laminated on the cushion layer, and transmits the uneven shape of the circuit formed on the surface of the semiconductor wafer to the cushion layer, and also transmits the semiconductor wafer and the cushion layer. This is adopted to attach and fix the.

Here, if the thickness of the pressure-sensitive adhesive layer is too large, the semiconductor wafer vibrates when polishing the semiconductor wafer, causing chipping or cracking of the semiconductor wafer. It is impossible to follow, and a gap is formed between the circuit and the semiconductor wafer protection sheet. If cooling water or polishing debris used for polishing the semiconductor wafer enters through the gap, the semiconductor wafer may be chipped or cracked. Therefore, the thickness is preferably 5 to 150 μm, and more preferably 10 to 60 μm.

As the pressure-sensitive adhesive layer, a general pressure-sensitive pressure-sensitive adhesive, an ultraviolet-curable pressure-sensitive adhesive, a heat-curable pressure-sensitive adhesive, or the like can be appropriately selected and employed. As the general pressure-sensitive pressure-sensitive adhesive, a conventionally known pressure-sensitive adhesive such as an acryl-based, rubber-based, or silicone-based pressure-sensitive adhesive can be appropriately selected and employed. The UV-curable pressure-sensitive adhesive is obtained by blending a curable compound and a UV-curable initiator with a general pressure-sensitive pressure-sensitive adhesive, and its adhesive strength can be adjusted by irradiation with ultraviolet rays. Further, the heat-curable pressure-sensitive adhesive is obtained by mixing a curable compound and a heat-curing initiator with a general pressure-sensitive pressure-sensitive adhesive, and can adjust the adhesive force by heating.

As the acrylic pressure-sensitive adhesive, a conventionally known acrylic pressure-sensitive adhesive can be appropriately selected and used. Generally, a homopolymer (main monomer) having an acrylate ester as a main constituent monomer unit And copolymers with other functional monomers (monomers containing functional groups), and mixtures of these polymers. Here, the main monomer includes, for example, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and the like, and the comonomer includes vinyl acetate, acrylonitrile, acrylamide, styrene,
Examples include methyl methacrylate and methyl acrylate.
Examples of the functional group-containing monomer include methacrylic acid, acrylic acid, itaconic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, dimethylaminoethyl methacrylate, acrylamide, methylol acrylamide, glycidyl methacrylate, and maleic anhydride.

Examples of the rubber-based pressure-sensitive adhesive include natural rubber, synthetic isoprene rubber, styrene-butadiene rubber,
Styrene / butadiene block copolymer, styrene / isoprene block copolymer, butyl rubber, polyisobutylene, polybutadiene, polyvinyl ether, silicone rubber, polyvinyl isobutyl ether, chloroprene rubber, nitrile rubber, kraft rubber, recycled rubber, styrene / ethylene / butylene -Block copolymer, styrene-propylene-butylene-block copolymer, styrene-isoprene-block polymer, acrylonitrile-butadiene copolymer, acrylonitrile-acryl ester copolymer, methyl methacrylate-butadiene copolymer, polyisobutylene-ethylene Propylene copolymer, ethylene vinyl acetate copolymer, polyisobutylene / silicone rubber, polyvinyl isobutyl ether / chloroprene, etc. It may be a mixture not only these alone product.

It is preferable to add a tackifying resin to the rubber-based pressure-sensitive adhesive in order to increase the adhesive strength. When the amount of the tackifying resin is too small, the adhesive effect of the adhesive containing an elastomer as a main component does not appear, and when the amount is too large, the performance reaches a peak.
00 parts by weight, more preferably 1 part by weight.
It is preferable to mix 0 to 30 parts by weight.

As the tackifying resin, rosin resin, terpene resin, aliphatic petroleum resin, aromatic petroleum resin,
There are hydrogenated petroleum resins, chroman-indene resins, styrene resins, alkylphenol resins, xylene resins and the like, alone or in mixtures, and terpene resins are preferred in view of compatibility with the elastomer. Examples of rosin resins include rosin, polymerized rosin, hydrogenated rosin, rosin ester, hydrogenated rosin ester, rosin modified phenol resin, and the like.
Examples of the terpene resin include a terpene resin, a terpene phenol resin, an aromatic modified terpene resin, a rosin phenol resin, and the like. Examples of the hydrogenated petroleum resin include aromatic resins, dicyclopentadiene resins, and aliphatic resins.

The curable compound compounded in the pressure-sensitive adhesive layer is combined with the ultraviolet curing initiator and the heat curing initiator to form the pressure-sensitive adhesive layer when the semiconductor wafer is separated from the semiconductor wafer protection sheet. This is adopted to adjust the adhesive strength of the rubber. With regard to the compounding ratio of the curable compound, if the amount is too small, the portion to be cured becomes small, so that the adhesive strength of the pressure-sensitive adhesive layer cannot be adjusted. Since it is cured by light and storage stability is deteriorated, the above-mentioned general pressure-sensitive adhesive 100
5 to 900 parts by weight based on parts by weight, preferably 2 to 900 parts by weight
0 to 200 parts by weight is good.

As the curable compound, specifically, a functional curable compound having two or more functional groups is preferable, for example, an acrylate compound, urethane acrylate, urethane acrylate oligomer and / or monomer, epoxy acrylate, There is a single or mixed system such as polyester acrylate.

Examples of the acrylate compound include trimethylolpropane triacrylate, tetramethylol methane tetraacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate and 1,4- Examples include butylene glycol diacrylate, 1,6-hexanediol diacrylate, polyethylene glycol diacrylate, and oligoester acrylate.

Examples of the urethane acrylate include polyester urethane acrylate, polyether urethane acrylate, 4-functional urethane acrylate, and hexafunctional urethane acrylate.

The urethane acrylate oligomer is an ultraviolet-curable compound having at least two carbon-carbon double bonds, such as a polyester compound or a polyether type polyol compound and a polyvalent isocyanate compound such as 2,4- Tolylene diisocyanate, 2,6-
Tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, terminal isocyanate urethane prepolymer obtained by reacting diphenylmethane 4,4-diisocyanate and the like,
An acrylate or methacrylate having a hydroxyl group, for example, 2-hydroxyethyl acrylate, 2
-Hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, polyethylene glycol acrylate, polyethylene glycol methacrylate, and the like.

When a urethane acrylate oligomer is employed, the molecular weight is not particularly limited.
When a material having a thickness of 00 to 30000 is used for the pressure-sensitive adhesive layer, the pressure-sensitive adhesive does not adhere to the semiconductor wafer even after polishing the back surface of the semiconductor wafer.

The above-mentioned epoxy acrylate is synthesized by reacting an epoxy group with acrylic acid or methacrylic acid, and includes bisphenol A type, bisphenol S type, bisphenol F type, epoxy oily type, phenol novolak type, There are ring types and the like.

As the above polyester acrylate,
Acrylic acid is condensed to OH groups remaining on the polyester skeleton synthesized from diols, polyols and dibasic acids to form acrylates. For example, phthalic anhydride / propylene oxide diol / acrylic acid, adipic acid /
Examples include 1,6-hexanediol / acrylic acid, trimellitic acid / diethylene glycol / acrylic acid, and the like.

The ultraviolet curing initiator and the heat curing initiator compounded in the pressure-sensitive adhesive layer are employed to promote the curing of the curable compound. If the compounding ratio of the UV curing initiator and the heat curing initiator is too large, the composition becomes sensitive to heat and light, and cures even at ambient temperature or sunlight, resulting in poor storage stability. Bad, 0.1 to 100 parts by weight of the curable compound
10 parts by weight is preferable, and preferably 0.5 to 5 parts by weight.

As the ultraviolet curing initiator, specifically,
Chloroacetophenone, diethoxyacetophenone, hydroxyacetophenone, 1-hydroxycyclohexylphenylketone, α-aminoacetophenone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholine Nopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2
-Hydroxy-2-methylpropan-1-one, mixed photoinitiator, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, allylketone-containing photoinitiator, benzoin, benzoin methyl ether, Benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin ether, benzyl dimethyl ketal, benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate,
4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4 ′
-Methyldiphenyl sulfide, 3,3′-dimethyl-4-methoxybenzophenone, methyl-O-benzoylbenzoate, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxan Son, isopropylthioxanthone, 2, 4
-Dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, α-
Acyl oxime esters, α-acyloxime esters,
Acylphosphine oxide, methylphenylglyoxylate, glyoxyester, 3-ketocoumarin, 2
-Ethylanthraquinone, camphorquinone, benzyl, 9,10-phenanthrenequinone, anthraquinone, dibenzosuberone, 4 ', 4''-diethylisophthalophenone,Michler's ketone, cyclic photoinitiator, tetramethylthiuram Monosulfide, 3,3 ', 4,4'
-Tetra (t-butylperoxycarbonyl) benzophenone and the like. As the above chloroacetophenone,
4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 4-t-butyl-trichloroacetophenone and the like.

The heat curing initiator includes an organic peroxide derivative and an azo-based polymerization initiator. The azo-based polymerization initiator is more preferably an organic peroxide derivative because nitrogen is generated during heating. Specific examples of the heat curing initiator include ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxyester, peroxydicarbonate, azobisisobutyronitrile and the like. .

When the above-mentioned UV-curable pressure-sensitive adhesive is employed as the pressure-sensitive adhesive layer of the present invention, a photo-initiating auxiliary may be added as required. Although the photoinitiator itself is not activated by irradiation with ultraviolet light, the initiation reaction is accelerated by using the ultraviolet light curing initiator alone when used in combination with the ultraviolet light curing initiator, and the curing reaction is made efficient. . Further, if necessary, an amine compound such as triethylamine, tetraethylpentamine, or dimethylaminoether may be used in combination as a polymerization accelerator.

As the photoinitiating auxiliary, there are mainly aliphatic and aromatic amines, specifically, triethanolamine,
Methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michler's ketone, 4,4′-diethylaminophenone, 4,4′-
Diethylaminobenzophenone, ethyl 2-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, 4
-(N-butoxy) ethyl dimethylaminobenzoate, 4-
Isoamyl dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, polymerizable tertiary amine, triethylamine, tetraethylpentaamine, dimethylaminoether, and the like.

In order to start the curing of the ultraviolet-curable compound and the heat-curable compound, it is necessary to irradiate and heat ultraviolet rays, respectively. The timing of irradiating or heating ultraviolet rays to cure these curable compounds is performed when the semiconductor wafer is peeled from the semiconductor wafer protection sheet. The irradiation amount of the ultraviolet rays is preferably in a range of ²⁰ to 500 mJ / cm ² at a frequency of 365 nm, and more preferably in a range of 50 to 150 mJ / cm ² . As the heating temperature, a temperature range of 50 to 150 ° C. is preferable. This is because if the irradiation or heating of the ultraviolet rays is too small, the cohesive strength cannot be improved, and if the irradiation or heating is too large, it takes time and the productivity is deteriorated.

As the support for the semiconductor wafer protection sheet according to the present invention, a conventionally known synthetic resin used as a support for the semiconductor wafer protection sheet can be employed, and an ultraviolet curable composition or the like is blended in the adhesive layer. In this case, since it is necessary to allow the ultraviolet rays from the support to reach the pressure-sensitive adhesive layer, the sheet needs to be an ultraviolet-permeable sheet. Specifically, a single layer, a composite layer or a plurality of layers of polyvinyl chloride, polybutene, polybutadiene, polyurethane, ethylene-vinyl acetate copolymer, polyethylene terephthalate, polyethylene, polypropylene and the like can be employed. The thickness of the support is selected from the range of 10 to 500 μm.

The semiconductor wafer protection sheet according to the present invention is stored by adhering a release paper or a release sheet such as a polyethylene laminated paper or a release-treated plastic film on an adhesive as required.

In the present invention, a sheet-like support,
In a sheet for protecting a semiconductor wafer having an adhesive layer laminated on one surface of a support, a cushion layer is provided between the support and the adhesive layer, and the dynamic elastic modulus of the cushion layer at 10 to 40 ° C. is 1 The circuit formed on the surface of the semiconductor wafer is about 100 μm by setting the thickness to 10 ^{−2 to} 5 × 10 ³ N / cm ² , the thickness to 10 to 300 μm, and the thickness of the adhesive layer to 5 to 150 μm. Even if it has unevenness, it does not create a gap between the circuit and the semiconductor wafer protection sheet, and the semiconductor wafer is chipped or broken when polishing the surface of the semiconductor wafer where the circuit is not formed. And a semiconductor wafer protection sheet free of the above.

[0051]

EXAMPLE An example of a semiconductor wafer protection sheet according to the present invention will be described with reference to Table 1 while comparing with a comparative example.

[0052]

[Table 1]

The semiconductor wafer protection sheet of this embodiment is
It has a sheet-shaped support having a thickness of 100 μm, a cushion layer having a thickness of 100 μm laminated on the surface of the support, and an adhesive layer having a thickness of 20 μm laminated on the surface of the cushion layer. Here, the support is made of polyethylene terephthalate, and the cushion layer is made of 100 parts by weight of a copolymer of ethyl acrylate-2-ethylhexyl acrylate as a base polymer and 100 parts by weight of a 6-functional urethane acrylate oligomer as an ultraviolet curable compound. Parts by weight, 3 parts by weight of 2,4-toluylene diisocyanate as a crosslinking agent and 8 parts by weight of benzoin isopropyl ether as an ultraviolet curing initiator are laminated on a support, and then ultraviolet rays having a frequency of 365 nm are laminated. 100mJ /
Irradiated at cm ² and cured to adjust the dynamic elastic modulus at 23 ° C. to 10 N / cm ² . The pressure-sensitive adhesive layer is obtained by blending 100 parts by weight of a copolymer of ethyl acrylate-2-ethylhexyl acrylate as a base polymer with 3 parts by weight of 2,4-toluylene diisocyanate as an ultraviolet curable compound. . The following comparative examples are the same as those in this example unless otherwise specified.

Here, in Table 1, the dynamic elastic modulus is measured by a measuring device R manufactured by Rheometric Scientific F.E.
According to DA-II, frequency 1 Hz, measurement temperature 10-4
It is a G ′ value obtained by sandwiching a material between two plates at 0 ° C., rotating one plate, and detecting a torque received by the other plate.

In Table 1, "wafer chipping" means that no chipping or crack was found in the semiconductor wafer by visual inspection after polishing a sample in which the semiconductor wafer protection sheet was attached to the circuit forming surface of the semiconductor wafer.も の was given, and x was found at any one of the chips and cracks. For polishing, about 15 cm (6 inches) in diameter and 400μ in thickness
m, the thickness of the wafer was 200 μm with a polishing machine (Backco grinder DFG-821F / 8 manufactured by Disco Corporation) for 30 samples each having a semiconductor wafer having a height of irregularities of 100 μm stuck on a semiconductor wafer protection sheet.
Polished until

Further, in Table 1, "conformity of irregularities" means "irregularities of circuit" and "semiconductor wafer protective sheet" are visually observed after polishing a sample in which a semiconductor wafer protective sheet is adhered to a circuit forming surface of a semiconductor wafer.隙間 indicates that no gap was found between them, and X indicates that a gap was found or cooling water or polishing debris entered the gap. The polishing was performed in the same manner as in the above-described polishing method for measuring the “wafer chip”.

In the present example, the ability to follow the wafer chipping and unevenness was evaluated as ○, and a target semiconductor wafer protection sheet was obtained.

In Comparative Example 1 in which the dynamic elastic modulus of the cushion layer was changed to 10 ⁵ N / cm ² , the wafer was chipped.
The irregularity followability was x, and the dynamic elastic modulus was 5 × 10
^In Comparative Example 2 in which the wafer was changed to ^-3 N / cm ² ,
It became.

In the embodiment, the thickness of the cushion layer is set to 40.
In Comparative Example 3 in which the thickness was changed to 0 μm, the chipping of the wafer was evaluated as x. In Comparative Example 4 in which the thickness of the cushion layer was changed to 5 μm, both the chipping of the wafer and the followability of the unevenness were evaluated as ×.

In the examples, the thickness of the pressure-sensitive adhesive layer was set to 200 μm.
In Comparative Example 5 where m was set, the chipping of the wafer was evaluated as x. In Comparative Example 6 in which the thickness of the pressure-sensitive adhesive layer was changed to 2 μm,
Both the chipping of the wafer and the followability of unevenness were evaluated as x.

[0061]

According to the present invention, there is provided a semiconductor wafer protection sheet having a sheet-like support and an adhesive layer laminated on one surface of the support, between the support and the adhesive layer. Providing a cushion layer, 10 to 40 ° C of the cushion layer
Dynamic elastic modulus of 1 × 10 ^{-2 to} 5 × 10 ³ N / cm ²
When the thickness of the adhesive layer is set to 10 to 300 μm and the thickness of the pressure-sensitive adhesive layer is set to 5 to 150 μm, even if the circuit formed on the surface of the semiconductor wafer has irregularities of about 100 μm, the circuit and the semiconductor wafer A semiconductor wafer protection sheet was obtained in which no gap was formed between the semiconductor wafer and the protection sheet, and the semiconductor wafer was not chipped or cracked when polishing the surface of the semiconductor wafer where no circuit was formed.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masanobu Kutsumi 2-13-1, Dai, Kamakura-shi, Kanagawa Prefecture Inside Toyo Kagaku Co., Ltd. (72) Inventor Masashi Kume 2-3-1, Kamakura, Kanagawa Prefecture No. Toyo Kagaku Co., Ltd. (72) Inventor Kiichi Araki 2-13-1, Dai, Kamakura-shi, Kanagawa F-term in Toyo Kagaku Co., Ltd. AB07 CA03 CA04 CA05 CA06 CB03 CC03 CE01 FA07 FA08

Claims (1)

[Claims] 1. A semiconductor wafer protection sheet having a sheet-shaped support and an adhesive layer laminated on one surface of the support, wherein a cushion layer is provided between the support and the adhesive layer. The cushion layer has a dynamic elastic modulus at 10 to 40 ° C. of 1 × 10 ^{−2 to} 5 × 10 ³ N / cm ² , a thickness of 10 to 300 μm, and a thickness of the pressure-sensitive adhesive layer of 5
A protective sheet for semiconductor wafers, having a thickness of from 150 to 150 μm.