JP6832784B2 - Adhesive tape for stealth dicing and manufacturing method of semiconductor chips using it - Google Patents

Description

The present invention relates to an adhesive tape for stealth dicing and a method for manufacturing a semiconductor chip using the adhesive tape.

For semiconductor wafers, after forming a circuit, adhesive tape is attached, and then cutting (dicing), cleaning, drying, stretching the adhesive tape (expanding), and peeling the element small pieces from the adhesive tape (pickup). It is made into a semiconductor chip through each process such as. The adhesive tape (dicing tape) used in these steps has sufficient adhesive strength to the cut element pieces (chips) from the dicing step to the drying step, but there is no adhesive residue during the peeling step. It is desired that the adhesive strength is reduced to some extent.

On the other hand, with the recent increase in performance and miniaturization of IC devices, the thickness of semiconductor chips has been reduced, and it has become necessary to reduce the thickness of wafers, which was about 350 μm in the past, to 100 μm or less. It was.

However, silicon, glass, and the like used as semiconductor wafers are brittle materials, and if the thickness becomes thin, they may be damaged during transportation or processing. In particular, if chipping or chipping occurs when the wafer is diced with a rotary blade, the bending strength of the chip is significantly reduced.

Therefore, as a method of suppressing the occurrence of chipping, laser light having a wavelength in the infrared region is focused inside the semiconductor wafer to form a modified layer, and the wafer is divided starting from the modified layer, so-called stealth. A method for dividing a wafer as a dicing has been proposed (Patent Document 1).

Further, Patent Document 2 proposes an adhesive tape for stealth dicing in which the Young's modulus of the adhesive tape at 23 ° C. and the storage elastic modulus of the adhesive layer at frequencies of 1 Hz and 23 ° C. are specified.

WO2003 / 077295 Japanese Unexamined Patent Publication No. 2011-119548

In stealth dicing in which laser light is condensed inside these semiconductor wafers to form a modified layer, the balance between the hardness of the pressure-sensitive adhesive layer and the stretchability of the base material layer is important. However, the adhesive tape described in Patent Document 2 has a high storage elastic modulus of the adhesive layer, and there is a possibility that the wafer slips from the adhesive tape during wafer division and cannot be divided. Further, since the pressure-sensitive adhesive layer is not specified, there is a possibility that the semiconductor chip cannot be peeled off from the pressure-sensitive adhesive tape after the wafer is divided.

The present invention has been made in view of the above problems, and the semiconductor wafer can be easily divided when the adhesive tape for stealth dicing is expanded after stealth dicing, and the chipped semiconductor chip can be easily peeled off. It is an object of the present invention to provide an adhesive tape for stealth dicing that can be used and a method for manufacturing a semiconductor chip using the adhesive tape.

The present invention employs the following means in order to solve the above problems.
(1) An adhesive tape for stealth dicing in which an ultraviolet curable adhesive layer is laminated on a base film.
The ultraviolet curable pressure-sensitive adhesive layer contains 100 parts by mass of a (meth) acrylic acid ester copolymer, 20 to 150 parts by mass of a urethane acrylate oligomer, 0.1 to 20 parts by mass of a polyfunctional isocyanate curing agent, and 0.1 parts by mass of a photopolymerization initiator. Contains 10 parts by mass
The tensile elastic modulus of the base film at 23 ° C. is 40 to 150 MPa.
The storage elastic modulus of the ultraviolet curable pressure-sensitive adhesive layer before irradiation with ultraviolet rays at a frequency of 1 Hz and 23 ° C. is 0.05 to 0.5 MPa.
An adhesive tape for stealth dicing having a weight average molecular weight of the urethane acrylate oligomer of 40,000 to 350,000.
(2) The adhesive tape for stealth dicing according to (1), wherein the ultraviolet curable adhesive layer has a thickness of 1 to 30 μm.
(3) The adhesive tape for stealth dicing according to (1) or (2), wherein the base film has a thickness of 30 to 150 μm.
(4) On a semiconductor wafer with a circuit formed on its surface,
(A) A sticking step of sticking the adhesive tape for stealth dicing according to any one of (1) to (3) to the semiconductor wafer and the ring frame.
(B) A stealth dicing step of irradiating a semiconductor wafer with a laser beam having a wavelength in the infrared region to form a modified layer inside the semiconductor wafer.
(C) A dividing step of dividing a semiconductor wafer into chips by expanding the adhesive tape for stealth dicing.
(D) An ultraviolet irradiation step of irradiating the base film surface of an adhesive tape for stealth dicing with ultraviolet rays,
(E) A peeling step of peeling a fragmented semiconductor chip from an adhesive tape for stealth dicing.
A method for manufacturing a semiconductor chip having and.

According to the present invention, the semiconductor wafer can be easily divided when the adhesive tape for stealth dicing is expanded after stealth dicing, and the adhesive tape for stealth dicing that can easily peel off the chipped semiconductor chip and the adhesive tape for stealth dicing. A method for manufacturing a semiconductor chip used can be provided.

Hereinafter, suitable embodiments for carrying out the present invention will be described. It should be noted that the embodiments described below show an example of typical embodiments of the present invention, and the scope of the present invention is not narrowly interpreted by this.

The present invention is an adhesive tape for stealth dying formed by laminating an ultraviolet curable pressure-sensitive adhesive layer on a base film, wherein the UV-curable pressure-sensitive adhesive layer is a specific component and tension of the base film. An adhesive tape for stealth dying in which the elastic modulus and the storage elastic modulus of the ultraviolet curable adhesive layer are specific numerical values.

<Base film>
The base film of the present invention is polyvinyl chloride, ethylene-vinyl acetate copolymer, ethylene-acrylic acid-acrylic acid ester film, ethylene-ethyl acrylate copolymer, polyethylene, polypropylene, propylene-based copolymer, ethylene-. Examples thereof include acrylic acid copolymers, and ionoma resins obtained by cross-linking ethylene- (meth) acrylic acid copolymers, ethylene- (meth) acrylic acid- (meth) acrylic acid ester copolymers, and the like with metal ions. The base film may be a mixture or copolymer of these resins, or may be a laminate of films or sheets made of these resins. The tensile elastic modulus of the base film at 23 ° C. is 40 MPa or more and 150 MPa or less, preferably 60 MPa or more and 120 MPa or less. Within this range, the semiconductor wafer can be easily divided when the adhesive tape for stealth dicing is expanded. If the tensile elastic modulus of the base film is less than 40 MPa , the force at the time of expanding is not sufficiently transmitted to the semiconductor wafer, and the splittability of the semiconductor wafer deteriorates. Also. When the tensile elastic modulus of the base film exceeds 150 MPa , the expandability is lowered and the splittability of the semiconductor wafer is lowered.

It is preferable to use ionomer resin as the base film. Among ionomer resins, an ionomer resin obtained by cross-linking a copolymer having an ethylene unit, a methacrylic acid unit, and a (meth) acrylic acid alkyl ester unit with ^{metal ions such as Na +} , K ⁺ , and Zn ^{2+ can be used for expansion.} It has good properties and is preferably used.

The thickness of the base film is preferably 30 to 150 μm, more preferably 50 to 120 μm.

The base film is preferably antistatic treated. Examples of the antistatic treatment include a treatment of blending an antistatic agent with the base film and a method of applying an antistatic agent to the surface of the base film.

As the antistatic agent, for example, a quaternary amine salt monomer or the like can be used. Examples of the quaternary amine salt monomer include dimethylaminoethyl (meth) acrylate quaternary chloride, diethylaminoethyl (meth) acrylate quaternary chloride, methylethylaminoethyl (meth) acrylate quaternary chloride, and p-dimethyl. Aminostyrene quaternary chloride and p-diethylaminostyrene quaternary chloride can be mentioned. Of these, dimethylaminoethyl methacrylate quaternary chloride is preferable.

An ultraviolet curable pressure-sensitive adhesive layer can be laminated on one side of the base film, and the other side can be an embossed surface having an average surface roughness (Ra) of 0.1 to 1.5 μm. By having the embossed surface, the base film can be easily expanded in the expanding step after dicing.

In order to improve the expandability after dicing, it is possible on the other side of the base film, or coated with a slip agent, kneading a slip agent to the substrate film.

The slip agent is not particularly limited as long as it is a material that reduces the coefficient of friction between the adhesive tape for stealth dying and the expanding device. Examples thereof include carbon black and molybdenum disulfide. These may be a mixture of a plurality of components. Since the electronic components are manufactured in a clean room, it is preferable to use a silicone compound or a fluororesin. Among the silicone compounds, a copolymer having a silicone macromonomer unit is preferably used because it has good compatibility with the antistatic layer and can balance antistatic property and expandable property.

<UV curable adhesive layer>
The ultraviolet curable pressure-sensitive adhesive layer contains a (meth) acrylic acid ester copolymer, a urethane acrylate oligomer, a polyfunctional isocyanate curing agent, and a photopolymerization initiator, is diluted with an organic solvent, applied to a base film, and dried. can get.
((Meta) acrylic acid ester copolymer)
The (meth) acrylic acid ester copolymer used in the present invention is a polymer obtained by polymerizing acrylic acid, methacrylic acid and their ester monomers, and an unsaturated monomer copolymerizable with these monomers (for example, vinyl acetate). , Styrene, acrylonitrile) and copolymerized.

Examples of the main monomer of the (meth) acrylic polymer include n-butyl (meth) acrylate, 2-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, and octyl (meth). Acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, tridecyl (meth) Examples thereof include (meth) acrylic monomers such as acrylate, myristyl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, and benzyl (meth) acrylate.

The (meth) acrylic monomer preferably has a monomer containing a functional group at least in part. Examples of the functional group include a hydroxyl group, a carboxyl group, an epoxy group, an amide group, an amino group, a methylol group, a sulfonic acid group, a sulfamic acid group and a phosphite ester group. Of these, a hydroxyl group is preferred.

Functional group-containing monomers having a hydroxyl group include, for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate.

Examples of the monomer having a carboxyl group include (meth) acrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, acrylamide N-glycolic acid, and cinnamic acid.

Examples of the monomer having an epoxy group include allyl glycidyl ether and glycidyl ether (meth) acrylate.

Examples of the monomer having an amide group include (meth) acrylamide and the like.

Examples of the monomer having an amino group include N, N-dimethylaminoethyl (meth) acrylate and the like.

Examples of the monomer having a methylol group include N-methylolacrylamide and the like.

(Urethane acrylate oligomer)
The urethane acrylate oligomer is obtained by reacting a (meth) acrylate having a hydroxy group with a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound such as a polyester type or a polyether type with a polyisocyanate compound.

Examples of the polyisocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane 4,4-diisocyanate, and trimethylhexamethylene diisocyanate. , Hexamethylene diisocyanate, isophorone diisocyanate and the like can be used. Examples of the (meth) acrylate having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polyethylene glycol (meth) acrylate, pentaerythritol triacrylate, and glycidoldi (meth). Acrylate, dipentaerythritol pentaacrylate and the like are used.

As the urethane acrylate oligomer, a urethane acrylate oligomer having four or more unsaturated double bonds is preferable in that the pressure-sensitive adhesive cures well after irradiation with ultraviolet rays or the like.

The weight average molecular weight of the urethane acrylate oligomer is 40,000 or more and 350,000 or less, preferably 80,000 to 200,000. If the weight average molecular weight of the urethane acrylate oligomer is less than 40,000, the splittability of the semiconductor wafer is lowered, and if it exceeds 350,000, the splitnability of the semiconductor wafer is lowered.

The blending amount of the urethane acrylate oligomer is 20 parts by mass or more and 150 parts by mass or less, preferably 40 parts by mass or more and 100 parts by mass or less, based on 100 parts by mass of the (meth) acrylic acid ester copolymer. If the blending amount of the urethane silicate oligomer is less than 20 parts by mass, it is difficult to peel off the semiconductor chip from the adhesive tape for adhesive stealth dicing after irradiation with ultraviolet rays, and if it exceeds 150 parts by mass, the splittability of the semiconductor wafer is lowered.

(Polyfunctional isocyanate curing agent)
A polyfunctional isocyanate curing agent is blended in the ultraviolet curable pressure-sensitive adhesive used for the UV-curable pressure-sensitive adhesive layer of the present invention. The composition of the polyfunctional isocyanate curing agent is 0.1 part by mass or more and 20 parts by mass or less, preferably 2 parts by mass or more and 15 parts by mass or less, based on 100 parts by mass of the (meth) acrylic polymer. If the compounding ratio of the polyfunctional isocyanate curing agent is less than 0.1 parts by mass, the splittability of the semiconductor wafer is lowered, and if it exceeds 20 parts by mass, the semiconductor wafer slips during expansion and the splitability is lowered.

Examples of the polyfunctional isocyanate curing agent include an aromatic polyisocyanate curing agent, an aliphatic polyisocyanate curing agent, and an alicyclic polyisocyanate curing agent. Further, an aliphatic polyisocyanate curing agent, particularly a hexamethylene diisocyanate curing agent thereof is preferable.

The aromatic polyisocyanate is not particularly limited, and for example, 1,3-phenylenediocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylenediocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2 , 6-Tolylene diisocyanate, 4,4'-toluidin diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4 ', 4'-Triphenylmethane triisocyanate, ω, ω'-diisocyanate-1,3-dimethylbenzene, ω, ω'-diisocyanate-1,4-dimethylbenzene, ω, ω'-diisocyanate-1,4- Examples thereof include diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate.

The aliphatic polyisocyanate is not particularly limited, and for example, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene. Examples thereof include diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate.

The alicyclic polyisocyanate is not particularly limited, and for example, 3-isocyanate methyl-3,5,5-trimethylcyclohexylisocyanate, 1,3-cyclopentanediisocyanate, 1,3-cyclohexanediisocyanate, 1,4-cyclohexanediisocyanate, methyl. -2,4-Cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,4-bis (isocyanatemethyl) cyclohexane, and 1,4-bis (isocyanatemethyl) cyclohexane There is.

Of the polyisocyanates, 1,3-phenylenediocyanate, 4,4'-diphenyldiisocyanate, 1,4-phenylenediocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate , 4,4'-toluene diisocyanate and hexamethylene diisocyanate are preferably used.

The polyfunctional epoxy curing agent mainly refers to a compound having two or more epoxy groups and one or more tertiary nitrogen atoms, and refers to NN-glycidylaniline, NN-glycidyltoluidine, m-NN-. Glycidylaminophenyl glycidyl ether, p-N ・ N-glycidyl aminophenyl glycidyl ether, triglycidyl isocyanurate, N ・ N ・ N'・ N'-tetraglycidyldiaminodiphenylmethane, N ・ N ・ N'・ N'-tetraglycidyl Examples thereof include -m-xylylene diamine, N, N, N', N', N "-pentaglycidyldiethylenetriamine and the like.

(Photopolymerization initiator)
Examples of the photopolymerization initiator include benzoins, acetophenones, anthraquinones, thioxanthones, ketals, benzophenones and xanthones.

Examples of benzoin include benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin propyl ether.
Examples of acetophenones include benzoin alkyl ethers, acetophenone, 2,2-dimethoxy-2-acetophenone, 2,2-diethoxy-2-acetophenone, 1,1-dichloroacetophenone, and 2-hirodoxy-1- {4-[ There are 4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propane-1-one, 1-hydroxycyclohexylphenylketone and the like.
Examples of anthraquinones include 2-methylanthraquinone, 2-ethylanthraquinone, 2-tershalibutyl anthraquinone, and 1-chloroanthraquinone.
Examples of thioxanthones include 2,4-dimethylthioxanthone, 2,4-diisopropylthioxanthone, 2-chlorothioxanthone, 2,4-diisopropylthioxanthone and the like.
Examples of ketals include acetophenone dimethyl ketal, benzyl dimethyl ketal , benzyl diphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, β-chloranthraquinone and the like.

The blending amount of the photopolymerization initiator is 0.1 to 10 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer. If the blending amount of the photopolymerization initiator is less than 0.1 parts by mass, the peelability decreases when the semiconductor chip is peeled from the adhesive tape for stealth dicing after irradiation with ultraviolet rays, and if it exceeds 10 parts by mass, the photopolymerization initiator is cured by ultraviolet rays. It bleeds out to the surface of the mold pressure-sensitive adhesive layer, and the splittability of the semiconductor wafer is lowered.

As the photopolymerization initiator, one or a combination of two or more conventionally known photopolymerization accelerators may be used in combination, if necessary. As the photopolymerization accelerator, a benzoic acid-based agent, a tertiary amine, or the like can be used. Examples of the tertiary amine include triethylamine, tetraethylpentamine, dimethylamino ether and the like.

Various additives such as a tackifier resin, a softener, an antiaging agent, a filler, a conductive agent, an ultraviolet absorber, and a light stabilizer may be added to the composition of the ultraviolet curable pressure-sensitive adhesive layer. ..

The thickness of the ultraviolet curable pressure-sensitive adhesive layer is preferably 1 μm or more and 30 μm, and particularly preferably 3 μm or more and 15 μm or less. If the UV-curable pressure-sensitive adhesive layer exceeds 30 μm, the peelability decreases when the semiconductor chip is peeled from the stealth dicing adhesive tape after UV irradiation. Further, if the ultraviolet curable pressure-sensitive adhesive layer is less than 1 μm, the adhesive strength becomes too low and the splittability of the semiconductor wafer is lowered.

<Manufacturing of adhesive tape for stealth dicing>
As a method of forming an ultraviolet curable adhesive layer on the base film to form an adhesive tape, for example, a coater such as a gravure coater, a comma coater, a bar coater, a knife coater or a roll coater is used to perform an ultraviolet curable adhesive on the base film. There are a method of directly applying the agent and a method of applying the adhesive to the release film / drying and then adhering it to the base film. The adhesive may be printed on the base film by convex plate printing, concave plate printing, flat plate printing, flexographic printing, offset printing, screen printing, or the like.

<Manufacturing method of semiconductor chips>
Specific steps of the method for manufacturing a semiconductor chip according to the present invention will be described in order.

(1) Sticking step In the sticking step, the adhesive tape for stealth dicing is stuck to the semiconductor wafer and the ring frame. The semiconductor wafer may be a conventional general-purpose wafer such as a silicon wafer, a gallium nitride wafer, a silicon carbide wafer, a glass wafer, or a sapphire wafer.

(2) Stealth dicing step In the stealth dicing step, the semiconductor wafer is irradiated with a laser beam having a wavelength in the infrared region to form a modified layer a plurality of times inside the semiconductor wafer. The wavelength in the infrared region varies depending on the type of semiconductor wafer, but a wavelength of 1,064 nm is often used.

(3) Dividing Step In the dividing step, the semiconductor wafer in which the modified layer is formed inside the semiconductor wafer by stealth dicing is divided by expanding.

(4) Ultraviolet irradiation step In the ultraviolet irradiation step, the ultraviolet curable pressure-sensitive adhesive layer is irradiated with active light such as ultraviolet rays from the base film side. As a light source of ultraviolet rays, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp can be used. Further, an electron beam may be used instead of the ultraviolet ray, and α ray, β ray, and γ ray can be used as the light source of the electron beam.

The ultraviolet curable adhesive layer is formed into a three-dimensional network and cured by ultraviolet rays, and the adhesive strength of the ultraviolet curable adhesive layer is reduced.

(5) Peeling step In the peeling step, the divided semiconductor chip is pushed up with a needle pin or the like. After that, the semiconductor chip or component is adsorbed by a vacuum collet or air tweezers and peeled from the ultraviolet curable adhesive layer.

Hereinafter, preferred embodiments of the present invention will be described in detail exemplarily. However, unless otherwise specified, the materials, blending amounts, and the like described in this example are not intended to limit the scope of the present invention to those alone, but are merely explanatory examples.

<Example>
Adhesive tapes for stealth dicing were prepared according to the formulations shown in Tables 1 and 2. The UV-curable pressure-sensitive adhesive layer is obtained by mixing a (meth) acrylic acid ester copolymer or the like with a UV-curable pressure-sensitive adhesive on a separator film made of polyethylene terephthalate, and the thickness of the UV-curable pressure-sensitive adhesive layer after drying is increased. It was obtained by coating so as to have a thickness of 10 μm. This ultraviolet curable adhesive layer was laminated on a base film and aged at 40 ° C. for 7 days to obtain an adhesive tape for stealth dicing.

[UV curable adhesive layer]
The following were used as each component of the ultraviolet curable pressure-sensitive adhesive layer.
((Meta) acrylic acid ester copolymer)
A-1: A copolymer containing 60% by mass of methyl acrylate, 35% by mass of 2-ethylhexyl acrylate, 4.5% by mass of acrylic acid and 0.5% by mass of 2-hydroxyethyl acrylate by solution polymerization. can get. Weight average molecular weight 200,000.
A-2: A copolymer containing 54% ethyl acrylate, 19% butyl acrylate and 24% methoxyethyl acrylate, which is obtained by emulsion polymerization. Weight average molecular weight 2 million.
(Urethane acrylate oligomer)
A hydroxyl group-containing acrylate containing dipentaerythritol pentaacrylate as a main component is prepared by a method known in JP-A-61-42529, JP-A-2012-36253, etc. in a trimeric isocyanate of isophorone diisocyanate. It is a urethane acrylate (synthetic product) having 15 unsaturated double bond functional groups. The weight average molecular weight was measured by gel permeation chromatography (GPC) and converted into polystyrene to obtain a weight average molecular weight.
B-1: Weight average molecular weight 11,000
B-2: Weight average molecular weight 43,000
B-3: Weight average molecular weight 79,000
B-4: Weight average molecular weight 154,000
B-5: Weight average molecular weight 338,000
B-6: Weight average molecular weight 385,000
Measurement of weight average molecular weight: Measurement was performed under the following conditions.
・ Equipment: GPC-8020 SEC system (manufactured by Tosoh Corporation)
-Column: TSK Guard HZ-L + HZM-N 6.0 x 150 mm x 3
・ Flow rate: 0.5 ml / min
-Detector: RI-8020
-Concentration: 0.2 wt / Vol%
・ Injection amount: 20 μL
-Column temperature: 40 ° C
・ System temperature: 40 ℃
-Solvent: THF
-Calibration curve: Made using standard polystyrene (manufactured by PL), and the weight average molecular weight (Mw) was expressed in polystyrene conversion value.
(Polyfunctional isocyanate curing agent)
C-1: Tosoh Coronate L-45E; 2,4-Tolylene diisocyanate trimethylolpropane adduct C-2: Tosoh Coronate HL; Hexamethylene diisocyanate trimethylolpropane adduct (photopolymerization initiator)
D-1: IRGACURE651 manufactured by BASF Japan; benzyldimethylketal D-2: IRGACURE184 manufactured by BASF Japan; 1-hydroxycyclohexylphenyl ketone [base film]
E-1: Ionomer resin (manufactured by Mitsui / DuPont Polychemical Co., Ltd., product number: HM1855) was formed into a film of 80 μm by T-die extrusion.
E-2: Polyethylene / ionomer resin / polyethylene (manufactured by Achilles, product number: HCVH) was formed into a film (composition ratio: 10/60/10) of 80 μm by two-kind three-layer T-die extrusion.
E-3: Polyvinyl chloride (manufactured by Diaphragm, product number: GM-311), 80 μm
E-4: An ethylene-vinyl acetate copolymer (manufactured by Tosoh Corporation, product number: 635) was formed into a film of 80 μm by calendar molding.
E-5: Polyvinyl chloride (manufactured by Achilles, product number: FUZB-2950), 80 μm

[Evaluation]
Various evaluations were carried out as follows.
(1) Measurement of Storage Elastic Modulus of UV Curable Adhesive Layer After producing a film in which an UV curable pressure-sensitive adhesive layer is laminated on a release film, it is die-cut into a cylindrical shape having a diameter of 8 mm. Then, the release film was peeled off, and the films were laminated so that the ultraviolet curable pressure-sensitive adhesive layer had a thickness of 1 mm to prepare a sample. The storage elastic modulus (G') at a frequency of 1 Hz and a temperature of 23 ° C. was measured by a torsional shearing method using a viscoelasticity measuring device (MCR-301 manufactured by Antonio Par).

(2) Measurement of Tensile Elastic Modulus of Base Film The tensile elastic modulus of the substrate film is measured in accordance with JIS K7161: 1994 using a universal tensile tester (Tencilon RTA-T-2M manufactured by Orientec). The measurement was performed at a tensile speed of 5 mm / min in an environment of 23 ° C. and 50% humidity.

(3) Evaluation of semiconductor wafer separability and peelability The semiconductor wafer splittability and peelability are determined by attaching an adhesive tape for stealth dicing to an 8-inch silicon wafer having a thickness of 300 μm and a ring frame, and then stealth dicing and expanding. evaluated.

The laser light irradiation conditions for stealth dicing are as follows.
-Light source: Nd-YAG laser-Wavelength: 1,064 nm
-Repeat frequency: 100 kHz
・ Laser output: 0.3W
・ Pulse width: 30ns
-Cut speed: 100 mm / sec-Cut tip size: 5 mm x 5 mm

The conditions for dividing the semiconductor wafer by expanding were as follows.
-Expanding device: HS-1800 manufactured by HUGLE ELECTRONICS
・ Expanding speed: 5 mm / sec ・ Withdrawal amount: 25 mm

The conditions for peeling were as follows.
-Peeling device: CAP-300II manufactured by Canon Machinery Co., Ltd.
・ Expanding amount: 5 mm
・ Needle pin shape: 250 μmR
・ Number of needle pins: 4 ・ Needle pin push-up height: 1.5 mm

1) Evaluation of Semiconductor Wafer Dividability After stealth dicing the semiconductor wafer, the adhesive tape for stealth dicing was expanded to divide the chips. The splittability of the semiconductor wafer was evaluated by the ratio of the number of divided semiconductor chips from the total number of divided semiconductor chips and undivided chips.
◎ (excellent): Semiconductor wafer division rate 95% or more ○ (Good): Semiconductor wafer division rate 90% or more and less than 95% × (impossible): Semiconductor wafer division rate less than 90%

2) Evaluation of peelability The peelability of the semiconductor chip was evaluated based on the number of the divided semiconductor chips that could be peeled off.
◎ (excellent): Semiconductor chip peeling success rate is 95% or more ○ (Good): Semiconductor chip peeling success rate is 80% or more and less than 95% × (impossible): Semiconductor chip peeling success rate is less than 80%

As shown in the results of Tables 1 and 2, the adhesive tape for stealth dicing of the examples of the present invention had good partitioning and peeling properties of the semiconductor wafer.
<Comparative example 1>
Since the amount of the urethane acrylate oligomer compounded is small, it is considered that the crosslink density of the ultraviolet curable pressure-sensitive adhesive layer after ultraviolet irradiation is low and the peelability is poor.
<Comparative example 2>
It is considered that the splittability of the semiconductor wafer was lowered because the amount of the urethane acrylate oligomer compounded was large and the storage elastic modulus of the ultraviolet curable pressure-sensitive adhesive layer was low.
<Comparative example 3>
It is considered that since the blending amount of the polyfunctional isocyanate curing agent is small, the storage elastic modulus of the ultraviolet curable pressure-sensitive adhesive layer is low, and the splittability of the semiconductor wafer is poor.
<Comparative example 4>
It is considered that the amount of the polyfunctional isocyanate curing agent compounded was large, the ultraviolet curable pressure-sensitive adhesive layer could not hold the semiconductor wafer, and the semiconductor wafer slipped during expansion, resulting in poor splittability.
<Comparative example 5>
Since the amount of the photopolymerization initiator compounded is small, it is considered that the crosslink density of the ultraviolet curable pressure-sensitive adhesive layer after ultraviolet irradiation is low and the peelability is poor.
<Comparative Example 6>
It is considered that the photopolymerization initiator bleeds out to the surface of the ultraviolet curable pressure-sensitive adhesive layer due to the large amount of the photopolymerization initiator blended, resulting in poor splittability of the semiconductor wafer.
<Comparative Example 7>
Since the weight average molecular weight of the urethane acrylate oligomer is low, the storage elastic modulus of the ultraviolet curable pressure-sensitive adhesive layer is low, and it is considered that the splittability of the semiconductor wafer is poor.
<Comparative Example 8>
Since the weight average molecular weight of the urethane acrylate oligomer is high, it is considered that the ultraviolet curable pressure-sensitive adhesive layer cannot hold the semiconductor, resulting in poor splittability of the semiconductor wafer.
<Comparative Example 9>
Since the tensile elastic modulus of the base film is low, it is considered that the force at the time of expanding is not sufficiently transmitted to the semiconductor wafer, causing a defect in the splittability of the semiconductor wafer.
<Comparative Example 10>
Since the tensile elastic modulus of the base film is high, it is considered that the expandability is lowered and the splittability of the semiconductor wafer is lowered.

Claims (4)

An adhesive tape for stealth dicing in which an ultraviolet curable adhesive layer is laminated on a base film.
The ultraviolet curable pressure-sensitive adhesive layer contains 100 parts by mass of a (meth) acrylic acid ester copolymer, 20 to 150 parts by mass of a urethane acrylate oligomer, 0.1 to 20 parts by mass of a polyfunctional isocyanate curing agent, and 0.1 parts by mass of a photopolymerization initiator. Contains 10 parts by mass
The tensile elastic modulus of the base film at 23 ° C. is 40 to 150 MPa.
The storage elastic modulus of the ultraviolet curable pressure-sensitive adhesive layer before irradiation with ultraviolet rays at a frequency of 1 Hz and 23 ° C. is 0.05 to 0.5 MPa.
An adhesive tape for stealth dicing having a weight average molecular weight of the urethane acrylate oligomer of 40,000 to 350,000. The adhesive tape for stealth dicing according to claim 1, wherein the ultraviolet curable adhesive layer has a thickness of 1 to 30 μm. The adhesive tape for stealth dicing according to claim 1 or 2, wherein the base film has a thickness of 30 to 150 μm. For semiconductor wafers with circuits formed on the surface
(A) A sticking step of sticking the adhesive tape for stealth dicing according to any one of claims 1 to 3 to a semiconductor wafer and a ring frame.
(B) A stealth dicing step of irradiating a semiconductor wafer with a laser beam having a wavelength in the infrared region to form a modified layer inside the semiconductor wafer.
(C) A dividing step of dividing a semiconductor wafer into chips by expanding the adhesive tape for stealth dicing.
(D) An ultraviolet irradiation step of irradiating the base film surface of an adhesive tape for stealth dicing with ultraviolet rays,
(E) A peeling step of peeling a fragmented semiconductor chip from an adhesive tape for stealth dicing.
A method for manufacturing a semiconductor chip having and.