TWI625376B - Adhesive sheet - Google Patents

Abstract

The invention provides an adhesive sheet (1), which comprises a substrate (2) and an adhesive layer (3) laminated on at least one side of the substrate (2). The adhesive layer (3) is hardened by energy rays. (Meth) acrylic acid ester copolymer (A) and epoxy-based crosslinking agent (B) are formed of an adhesive composition, and the (meth) acrylic acid ester copolymer (A) is an acrylic copolymer (AP) The acrylic copolymer (AP) is obtained by reacting with a hardening group-containing compound (A4). The acrylic copolymer (AP) is an alkyl (meth) acrylate monomer (A1), a hydroxyl-containing monomer (A2) having a hydroxyl group, And a functional group-containing monomer (A3) having a functional group capable of reacting with an epoxy group, the functional group does not include a hydroxyl group, and the hardening group-containing compound (A4) has a function capable of reacting with a hydroxyl group Carbon-carbon double bonds that are hardened by the base and energy rays. According to this type of adhesive sheet (1), the adhesiveness between the adhesive layer (3) and the substrate (2) is excellent even after irradiation with energy rays.

Description

Adhesive sheet

The present invention relates to an adhesive sheet for an adhesive layer having energy ray-hardening properties.

Conventionally, for example, in the process of grinding and cutting a semiconductor wafer, an adhesive sheet is used for the purpose of fixing the semiconductor wafer and protecting the circuit and the like. As the adhesive sheet, an adhesive sheet including an energy ray-curable adhesive layer may be used. The energy ray-curable adhesive layer has a strong adhesive force in a processing process after the semiconductor wafer is attached. On the other hand, the adhesive force at the time of peeling decreases due to the irradiation of energy rays.

The energy-ray-curable adhesive layer as described above is usually formed of an adhesive composition containing an energy-ray-curable adhesive component and, if necessary, a crosslinking agent. As the energy-ray-curable adhesive component, those containing an acrylic polymer and an energy-ray-curable compound having no energy-ray-curable properties, or those containing an acrylic polymer having an energy-ray-curable group introduced into a side chain are generally used.

As an adhesive sheet using an adhesive containing an acrylic polymer having an energy ray-curable group introduced into its side chain, for example, those described in Patent Documents 1 and 2 are known. In the example of Patent Document 1, after copolymerizing 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate and octadecyl acrylate, the copolymer is copolymerized. A (meth) acrylic polymer obtained by reacting with 2-isocyanatoethyl methacrylate, a polyisocyanate compound as a crosslinking agent, and a photopolymerization initiator are mixed to prepare a radiation-curing adhesive The composition is laminated with an adhesive layer composed of the radiation-curable adhesive composition and a base film as an adhesive sheet for cutting.

Further, in the example of Patent Document 2, n-butyl acrylate, A polymerizable polymer obtained by copolymerizing ethyl acrylate, acrylic acid, and 2-hydroxyethyl acrylate after the copolymer is reacted with 2-isocyanatoethyl methacrylate, and pentaerythritol tris as a multifunctional oligomer. Acrylate, a polyisocyanate compound as a cross-linking agent, and a photopolymerization initiator are mixed to prepare a repeelable peeling adhesive, and an adhesive layer and a base film composed of the repeelable peeling adhesive are laminated for cutting. Adhesive sheet.

[Patent Literature]

Patent Document 1: Japanese Patent Application Laid-Open No. 2010-232629

Patent Document 2: Japanese Patent No. 2887274

When the adhesive sheet of Patent Document 1 or 2 is used, after the adhesive sheet is attached to a semiconductor wafer and diced, the adhesive layer is irradiated with energy rays such as ultraviolet rays to reduce the adhesive force, and peeled off from the adhesive layer of the adhesive sheet The wafer is picked up.

However, in the adhesive sheets of Patent Documents 1 and 2, since the adhesion between the base film and the adhesive layer is reduced after the energy rays are irradiated, it is as above. When picking up, peeling occurs between the base film and the adhesive layer, and sometimes the wafer cannot be picked up well from the adhesive layer.

The present invention has been completed in view of the actual situation as described above. The object is to provide an adhesive sheet having excellent adhesion between the adhesive layer and the substrate even after irradiation with energy rays.

In order to achieve the above object, first, the present invention provides an adhesive sheet including a substrate and an adhesive layer laminated on at least one side of the substrate, the adhesive layer is formed by an adhesive composition, and the adhesive The composition contains an energy-ray-curable (meth) acrylate copolymer (A) and an epoxy-based crosslinking agent (B), and the (meth) acrylate copolymer (A) is an acrylic copolymer (AP) ) Obtained by reacting with a hardenable group-containing compound (A4), the acrylic copolymer (AP) is a (meth) acrylic acid alkyl ester monomer (A1), a hydroxyl-containing monomer (A2) having a hydroxyl group And copolymerized with a functional group-containing monomer (A3) having a functional group (excluding a hydroxyl group) capable of reacting with an epoxy group, and the aforementioned hardening group-containing compound (A4) has a functional group capable of reacting with a hydroxyl group And energy-ray-curable carbon-carbon double bonds (Invention 1).

According to the above-mentioned invention (Invention 1), the adhesive layer is formed of an adhesive composition containing the (meth) acrylate copolymer (A) and the epoxy-based cross-linking agent (B), whereby even after irradiation with energy rays The adhesion between the adhesive layer and the substrate is also excellent.

In the above-mentioned invention (Invention 1), the (meth) acrylate copolymer (A) contains 50 mol% or more of hydroxy groups derived from the (meth) acrylate copolymer (A). The aforementioned hardening group-containing compound The hardening group (A4) is preferred (Invention 2).

In the said invention (Inventions 1, 2), it originates in said (methyl) The proportion of the mass of the structural part of the alkyl acrylate monomer (A1) in the mass of the aforementioned (meth) acrylate copolymer (A) is preferably 50 to 99% by mass (Invention 3).

In the above invention (Inventions 1 to 3), the (meth) acrylic acid The number of carbon atoms in the alkyl group of the alkyl ester monomer (A1) is preferably 6 or more (Invention 4).

In the above invention (Inventions 1 to 4), the functional group-containing monomer The proportion of the mass of the structural part of the body (A3) in the entire mass of the aforementioned (meth) acrylate copolymer (A) is preferably 0.1 to 5% by mass (Invention 5).

In the above invention (Inventions 1 to 5), the above-mentioned hydroxyl-containing monomer is derived The proportion of the mass of the structural part (A2) in the mass of the aforementioned acrylic copolymer (AP) is preferably 1 to 25% by mass (Invention 6).

In the above inventions (Inventions 1 to 6), it is preferable that the base material is a polyolefin film as a main body (Invention 7).

In the above inventions (Inventions 1 to 7), the adhesive sheet is preferably an adhesive sheet for semiconductor processing (Invention 8).

The adhesive sheet of the present invention is excellent in adhesion between the adhesive layer and the substrate even after the energy ray is irradiated.

1‧‧‧ adhesive sheet

2‧‧‧ substrate

3‧‧‧ Adhesive layer

FIG. 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described.

FIG. 1 is a cross-sectional view of an adhesive sheet according to an embodiment of the present invention. The adhesive sheet 1 according to this embodiment includes a base material 2 and an adhesive layer 3 laminated on one surface of the base material 2 (the upper surface in the first figure). The adhesive sheet 1 according to this embodiment can be used as, for example, an adhesive sheet for semiconductor processing such as a dicing sheet using a semiconductor wafer or the like as an adherend, or a back-side polishing sheet, but is not limited thereto. Hereinafter, the case where it is used as a dicing sheet or a back-side polishing sheet will be mainly described.

1. Substrate

As long as the base material 2 of the adhesive sheet 1 of this embodiment plays a desired role in the use process of the adhesive sheet 1, for example, it does not break in the back-grinding process, cutting process, expansion process, etc., the constituent materials are not particularly limited. Generally, a film (resin film) mainly composed of a resin-based material is preferably used, and a resin film is preferred. Specific examples of the resin film include ethylene-based copolymer films such as ethylene-vinyl acetate copolymer films, ethylene- (meth) acrylic copolymer films, and ethylene- (meth) acrylate copolymer films; low density Polyethylene (LDPE) film, linear low-density polyethylene (LLDPE) film, high-density polyethylene (HDPE) film and other polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene Polyolefin films, such as vinylene films, ethylene-norbornene copolymer films, norbornene resin films, etc., which use olefins only as the polymerization monomer; polyvinyl chloride films, such as polyvinyl chloride films, vinyl chloride copolymer films; Polyester films such as ethylene terephthalate film, polybutylene terephthalate film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; fluororesin film, etc. Also, such cross-linking can be used Modified films such as films and ionomer films. The above-mentioned base material 2 may be a resin film composed of one of these, and may also be a laminated film formed by combining two or more of these. In addition, "(meth) acrylic acid" in this specification means both acrylic acid and methacrylic acid. The same applies to other similar terms.

Among the above, a polyolefin-based film is preferred, and a polyethylene film Polypropylene film is particularly preferred, and polypropylene film is further preferred. These polyolefin-based films are excellent in heat resistance and solvent resistance.

In the base material 2, a pigment, Various additives such as dyes, flame retardants, plasticizers, antistatic agents, slip agents, fillers, etc. Examples of the pigment include titanium dioxide and carbon black. Examples of the filler include organic materials such as melamine resin, inorganic materials such as fumed silica, and metal materials such as nickel particles. The content of such additives is not particularly limited, but the base material 2 should perform the desired function and be limited to a range that does not lose smoothness and softness.

When ultraviolet rays are used to irradiate to harden the adhesive layer 3 In the case of an energy ray, it is preferred that the substrate 2 is transparent to ultraviolet rays. In addition, when an electron beam is used as the energy ray, it is preferable that the base material 2 has electron beam permeability.

Here, in the technical field, it is known to improve A primer layer is provided on the surface of the resin film because of its adhesiveness. However, in this case, a film-forming process such as coating is required, which is the main reason for the increase in cost, which is not desirable. When the adhesive layer 3 of this embodiment is used, the adhesiveness with a resin film is excellent even if there is no primer layer.

As long as the adhesive sheet 1 can properly function during use, The thickness of the substrate 2 is not limited, but is usually preferably 20 to 450 μm, more preferably 25 to 300 μm, and more preferably 50 to 200 μm.

The elongation at break of the substrate 2 in this embodiment is 23 ° C, When the relative humidity is 50%, the measured value is more than 100%, more preferably 200 ~ 1000%. Here, the elongation at break is the elongation of the length of the test piece when the test piece is broken in a tensile test in accordance with JIS K7161: 1994 (ISO 527-1 1993) with respect to the original length. The above-mentioned base material 2 having a breaking elongation of 100% or more is difficult to break during the expansion process, and becomes a wafer detacher that is easy to cut off a workpiece.

In addition, the substrate 2 is stretched at 25% strain in the present embodiment. The stress is preferably 5 to 15 N / 10 mm, and the maximum tensile stress is preferably 15 to 50 MPa. Here, the tensile stress at 25% strain and the maximum tensile stress were measured by a test according to JIS K7161: 1994. If the tensile stress at 25% strain is 5N / 10mm or more and the maximum tensile stress is 15MPa or more, the substrate 2 can be suppressed when the workpiece is fixed on a frame such as a ring frame after the workpiece is adhered to the adhesive sheet 1. Since slack is generated, it is possible to prevent a transport error. On the other hand, if the tensile stress at 25% strain is 15 N / 10 mm or less and the maximum tensile stress is 50 MPa or less, peeling of the adhesive sheet 1 from the ring frame or the like during the expansion process can be suppressed. The above-mentioned elongation at break, tensile stress at 25% strain, and maximum tensile stress are values measured in the substrate 2 along the longitudinal direction of the roll film.

2. Adhesive layer

The adhesive layer 3 is formed of an adhesive composition containing an energy ray-curable (meth) acrylate copolymer (A) and an epoxy-based crosslinking agent (B).

(1) (meth) acrylate copolymer (A)

The energy-ray-curable (meth) acrylate copolymer (A) is made by combining an alkyl (meth) acrylate monomer (A1), a hydroxyl-containing monomer (A2) having a hydroxyl group, and Acrylic copolymer (AP) copolymerized with functional group-containing monomer (A3), functional group (excluding hydroxyl group), and carbon-carbon having functional group capable of reacting with hydroxyl group and energy ray hardening property The double bond-containing hardening group-containing compound (A4) is obtained by a reaction.

The (meth) acrylate copolymer (A) can contain (a As the monomer unit constituting the copolymer, the alkyl acrylate monomer (A1) exhibits better adhesion. As the (meth) acrylic acid alkyl ester monomer (A1), the number of carbon atoms in the alkyl group is preferably 6 or more, 8 to 18 is particularly preferable, and 10 to 14 is more preferable. When the number of carbon atoms in the alkyl group of the alkyl (meth) acrylate monomer (A1) is 6 or more, the obtained adhesive layer 3 becomes one having excellent solvent resistance. For example, when the adhesive sheet 1 is used as a dicing sheet, the adhesive remaining on the semiconductor wafer is removed after the back-side polishing sheet is peeled from the semiconductor wafer, or the adhesive is removed by dissolving the adhesive in a solvent for processing such as grinding. When a semiconductor wafer is fixed to the supporting substrate with an adhesive, or after the peeling, the adhesive remaining on the semiconductor wafer is removed by a solvent after the peeling, etc., and the dicing sheet attached to the semiconductor wafer may also be used. In contact with solvents. Even in this case, the adhesive layer 3 does not swell, dissolve, and the like, and maintains a good layer state and a state of adhesion to the adherend.

In addition, if the alkyl group of the (meth) acrylic acid alkyl ester monomer (A1) is When the number of carbon atoms of the group is 6 or more, the adhesion force to the adherend is easily reduced after the energy rays are irradiated. Here, in general, if the content of the (meth) acrylic acid alkyl ester monomer having a longer side chain in the (meth) acrylic acid ester copolymer increases, The reaction efficiency of the crosslinking agent bonded to a trace amount of a carboxyl group or the like with a functional group of the (meth) acrylate copolymer is deteriorated, and thus the adhesion between the adhesive layer and the substrate tends to decrease. . However, according to this embodiment, even in this case, an effect of maintaining excellent adhesion between the adhesive layer 3 and the substrate 2 can be obtained.

As the above-mentioned solvent, a solvent having a higher polarity is preferable, and specifically, a solvent having a dissolution parameter (SP value) of 9 to 12, especially 10 to 12 (cal / cm ³ ) ^1/2 is preferable. Object. Examples of such a solvent include N-methylpyrrolidone (NMP), ethyl acetate, acetone, and methyl ethyl ketone. Among these, N-methylpyrrolidone (NMP) is particularly preferred.

As the (meth) acrylic acid alkyl ester monomer (A1), for example, Examples include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-amyl (meth) acrylate, and n-hexyl (meth) acrylate Ester, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, tetradecyl (meth) acrylate , Cetyl (meth) acrylate, octadecyl (meth) acrylate, and the like.

In addition, (methyl) having 6 or more carbon atoms as an alkyl group The alkyl acrylate monomer (A1) is preferably one having 6 to 18 carbon atoms in the alkyl group. Examples include n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Isooctyl (meth) acrylate, n-decyl (meth) acrylate, lauryl (meth) acrylate, tetradecyl (meth) acrylate, cetyl (meth) acrylate, (formyl) Octadecyl acrylate and the like. Among these, lauryl (meth) acrylate, tetradecyl (meth) acrylate, and decyl (meth) acrylate Hexyl ester, octadecyl (meth) acrylate, and the like are preferred. The alkyl (meth) acrylate monomer (A1) can be used alone or in combination of two or more.

Derived from the structural part of the alkyl (meth) acrylate monomer (A1) The proportion of parts by mass in the overall mass of the (meth) acrylate copolymer (A) is preferably 50 to 97% by mass, particularly preferably 60 to 95% by mass, and 70 to 90% by mass is even more preferred . When the ratio of the mass of the structural portion derived from the (meth) acrylic acid alkyl ester monomer (A1) is within the above range, the solvent resistance of the adhesive layer 3 is further improved.

C as the precursor of (meth) acrylate copolymer (A) The enoic acid-based copolymer (AP) has both a hydroxyl-containing monomer (A2) and a functional group-containing monomer (A3) as a monomer unit constituting the copolymer, thereby having the same properties as a hardening group-containing compound ( A4) a reaction point (a hydroxyl group of a hydroxyl group-containing monomer (A2)) and a reaction point (a functional group containing a functional group monomer (A3)) that reacts with an epoxy-based crosslinking agent (B). Thereby, the introduction amount of the hardening group based on the hardening group-containing compound (A4) and the reaction amount with the epoxy-based crosslinking agent (B) can be adjusted to a desired amount, and the obtained adhesive layer 3 can be adjusted. The energy ray hardenability and the degree of crosslinking are controlled in a better range. Therefore, in order to increase the addition rate of the hydroxyl group of the curable group-containing compound (A4) to the acrylic copolymer (AP), the crosslinking can be effectively performed even when the residual hydroxyl group is reduced.

This kind of adhesive layer 3 communicates with the substrate 2 even after irradiating energy rays. Is also excellent in adhesion. Therefore, when the adherend and the adhesive sheet 1 are separated after being irradiated with energy rays, peeling of the substrate 2 and the adhesive layer 3 in the adhesive sheet 1 can be effectively suppressed. In addition, the above-mentioned adhesive layer 3 becomes an adhesive before and after irradiation with energy rays. Focus on the better. In other words, the adhesive force to the adherend is sufficiently high before the energy ray is irradiated, and the adhesive force to the adherend is sufficiently low after the energy ray is irradiated. In addition, when the adhesive layer 3, the substrate 2 composed of a resin film, and the substrate 2 composed of a polyolefin-based film are directly laminated, the above-mentioned adhesive effect can be particularly effectively exhibited.

Examples of the hydroxyl-containing monomer (A2) include (meth) acrylic acid 2-hydroxyethyl enoate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate Esters, and hydroxyalkyl (meth) acrylates, such as 4-hydroxybutyl (meth) acrylate. Among these, from the viewpoint of reactivity with the curable group-containing compound (A4), 2-hydroxyethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferred. These can be used alone or in combination of two or more.

The quality of the structural part derived from the hydroxyl-containing monomer (A2) is in propylene The proportion of the entire mass of the acid-based copolymer (AP) is preferably 1 to 25% by mass, particularly preferably 5 to 25% by mass, and 7 to 15% by mass is further preferred. When the proportion of the mass of the structural portion derived from the hydroxyl-containing monomer (A2) is within the above range, the amount of the hardening group based on the hardening group-containing compound (A4) and the amount of residual hydroxyl groups can be controlled to a better level. Range. This makes it possible to sufficiently reduce the adhesive force of the adhesive layer 3 after the energy rays are irradiated.

As a functional group capable of reacting with epoxy groups (not included Examples of the functional group of the functional group-containing monomer (A3) include a carboxyl group, an amino group, and an aziridinyl group. Among them, a carboxyl group having a higher reactivity with an epoxy group than a hydroxyl group is more suitable. good. By setting the functional group of the functional group-containing monomer (A3) as a carboxyl The group reacts selectively with the epoxy group of the epoxy-based cross-linking agent (B), so that an adhesive having excellent effects in this embodiment can be obtained.

Examples of the carboxyl group-containing monomer include acrylic acid and formic acid. Ethylene unsaturated carboxylic acids such as acrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Examples of the amino group-containing monomer include aminoethyl (meth) acrylate and n-butylaminoethyl (meth) acrylate. The functional group-containing monomer (A3) can be used alone or in combination of two or more.

The mass of the structural part derived from the functional group-containing monomer (A3) is in (A The proportion of the total mass of the acrylate) acrylate copolymer (A) is preferably 0.1 to 5% by mass, more preferably 0.3 to 3% by mass, and even more preferably 0.3 to 2% by mass. When the proportion of the mass of the structural portion derived from the functional group-containing monomer (A3) is within the above range, the amount of reaction with the epoxy-based crosslinking agent (B) can be controlled to a preferable range to set the crosslinks well. Degree of connection. Thereby, the adhesiveness of the adhesive layer 3 and the base material 2 after irradiation with an energy ray can be improved.

The (meth) acrylate copolymer (A) contains, in addition to the above In addition to the monomers, other monomers may be contained as necessary as a monomer unit constituting the copolymer. Examples of other monomers include methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, and ethoxy (meth) acrylate Non-crosslinking properties such as (meth) acrylates containing aromatic rings, such as alkoxyalkyl (meth) acrylates and phenyl (meth) acrylates, such as ethyl esters, acrylamide, and methacrylamide Non-crosslinkable tertiary amino (meth) acrylic acid such as acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate Esters, vinyl acetate, styrene, etc. These can be used alone or in combination. on.

The acrylic copolymer (AP) can be obtained by a conventional method. It is obtained by copolymerizing each monomer. The polymerization state of the acrylic copolymer (AP) may be either an amorphous copolymer or a block copolymer.

Hardening group-containing compound (A4) is used for (meth) propylene The acid ester copolymer (A) imparts energy ray hardenability. Examples of the functional group capable of reacting with the hydroxyl group of the curable group-containing compound (A4) include an isocyanate group, an epoxy group, and a carboxyl group. Among them, an isocyanate group having a high reactivity with a hydroxyl group is preferable .

Energy-ray hardening in the hardening group-containing compound (A4) Sexual carbon-carbon double bonds. It is preferred that the hardening group-containing compound (A4) contains 1 to 5 carbon-carbon double bonds of this energy ray-hardening property per molecule, and it is more preferable to contain 1 to 2 carbon-carbon double bonds.

Examples of such a curable group-containing compound (A4) include 2-methylpropenyloxyethyl isocyanate, methyl-isopropenyl-α, α-dimethylbenzyl isocyanate, methacrylic acid isocyanate, allyl isocyanate, 1,1- (bispropenyloxy Methyl) ethyl isocyanate; propylene-monoisocyanate compound obtained by reaction of diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth) acrylate; by diisocyanate compound or polyisocyanate compound, polyol compound Acrylic fluorene monoisocyanate compound obtained by reaction with hydroxyethyl (meth) acrylate. Among these, 2-methacryloxyethyl isocyanate is particularly preferable. The hardening group-containing compound (A4) may be used alone or in combination of two or more.

In the (meth) acrylate copolymer (A), Base) The hydroxyl group of the acrylate copolymer (A) contains 50 mol% or more The hardenable group derived from the hardenable group-containing compound (A4) is more preferably 70 to 400 mol%, and more preferably 90 to 200 mol%. When the curable group-containing compound (A4) is monofunctional, the upper limit is 100 mol%, but when the curable group-containing compound (A4) is polyfunctional, it may exceed 100 mol%. When the ratio of the hardenable group with respect to the hydroxyl group is 50 mol% or more, the introduction amount of the hardenable group becomes sufficient, and the residual hydroxyl group in the (meth) acrylate copolymer (A) decreases. This makes it possible to sufficiently reduce the adhesive force of the adhesive layer 3 after the energy rays are irradiated. In addition, if the ratio of the hardenable group to the hydroxyl group is 70 mol% or more, the possibility of reducing the adhesive force after irradiation with energy rays to a level of 115 mN / 25 mm or less is increased. When used as a dicing sheet, even the area Larger wafers can also be easily picked up. In addition, if the ratio of the hardenable group to the hydroxyl group is too large, the adhesive force of the adhesive layer 3 after the energy rays are irradiated may be excessively lowered, and the wafer may fall off the dicing sheet before being picked up.

Acrylic copolymer (AP) and hardening group-containing compound (A4) The reaction can be carried out by a conventional method. Through this reaction process, a hydroxyl group in the acrylic copolymer (AP) and a functional group (a functional group capable of reacting with a hydroxyl group, such as an isocyanate group) in the curable group-containing compound (A4) react to introduce a hardening group. To the side chain of the acrylic copolymer (AP), an energy ray-curable (meth) acrylate copolymer (A) can be obtained.

Weight average molecular weight of (meth) acrylate copolymer (A) It is preferably 150,000 to 2 million, especially 200,000 to 1.5 million, and more preferably 250,000 to 1.2 million. In addition, the weight average molecular weight in this specification is a standard polystyrene conversion value measured by the gel permeation chromatography (GPC) method.

If the weight average molecule of (meth) acrylate copolymer (A) When the amount is 150,000 or more, a decrease in cohesiveness of the adhesive layer 3 before curing can be suppressed. For example, when used as a dicing sheet, it is possible to reduce the possibility of chipping (chipping) at the end of the wafer. If the weight average molecular weight of the (meth) acrylate copolymer (A) is 2 million or less, the coating composition can be avoided when the adhesive layer 3 is formed by coating the coating composition. The viscosity is too high to make coating difficult.

In addition, in the adhesive composition P, a (meth) acrylate copolymer (A) may be used individually by 1 type, and may use 2 or more types together. The adhesive composition P may further contain a (meth) acrylate polymer different from the (meth) acrylate copolymer (A).

Examples of energy rays for curing the (meth) acrylate copolymer (A) include ionizing radiation, that is, X-rays, ultraviolet rays, and electron rays. Among these, it is preferable that ultraviolet rays which are relatively easy to be introduced into the irradiation equipment.

When ultraviolet rays are used as the ionizing radiation, in view of ease of operation, near ultraviolet rays including ultraviolet rays having a wavelength of about 200 to 380 nm may be used. As the amount of light that the thickness (meth) acrylate copolymer (A) and the kind of the adhesive agent layer 3 can be suitably selected, usually about ^{50 ~ 500mJ / cm 2, 100} ~ 450mJ / cm 2 are preferred, 200 ~ 400mJ / cm ^{2 is} more preferable. Further, the intensity of ultraviolet is generally 50 ~ 500mW / about ^{cm 2, 100 ~ 450mW / cm} 2 is preferred, 200 ~ 400mW / cm ² is more preferred. The ultraviolet source is not particularly limited, and for example, a high-pressure mercury lamp, a metal halide lamp, or a UV-LED can be used.

When an electron beam is used as the ionizing radiation, the acceleration voltage may be appropriately selected according to the type of the (meth) acrylate copolymer (A) and the thickness of the adhesive layer 3. The acceleration voltage is usually about 10 to 1000 kV. for Better. In addition, the irradiation dose may be set within a range where the (meth) acrylate copolymer (A) is appropriately cured, and is usually selected within a range of 10 to 1000 krad. The electron beam source is not particularly limited. For example, a Cockcroft-Walton type, a Van DeGraff type, a resonance transformer type, an insulated core transformer type, or a linear type can be used. Various electron beam accelerators such as ground nanometer and high frequency.

(2) Epoxy crosslinking agent (B)

The epoxy-based crosslinking agent (B) crosslinks the (meth) acrylate copolymer (A) by reacting with a functional group capable of reacting with an epoxy group in the (meth) acrylate copolymer (A). . The functional group capable of reacting with the epoxy group in the (meth) acrylate copolymer (A) is derived from the functional group-containing monomer (A3). Since a suitable amount is present in the (meth) acrylate copolymer (A), ), The degree of cross-linking can be controlled in a better range. Thereby, in the obtained adhesive layer 3, the cohesiveness of the adhesive layer 3 can be maintained well before the energy ray is irradiated, and the adhesion with the substrate 2 can be sufficiently improved after the energy ray is irradiated.

Examples of the epoxy-based crosslinking agent (B) include 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl Methylene xylene diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidylamine, and the like. The epoxy-based crosslinking agent (B) may be used singly or in combination of two or more kinds.

The content of the epoxy-based cross-linking agent (B) forming the adhesive composition of the adhesive layer 3 is preferably 0.01 to 5 parts by mass relative to 100 parts by mass of the (meth) acrylate copolymer (A), and 0.05 to 0.05 parts by mass. 3 parts by mass is particularly preferred, 0.08 ~ 2 mass Portions are further preferred. When the content of the epoxy-based crosslinking agent (B) is in the above range, the cohesiveness of the adhesive layer 3 can be maintained well before the energy ray is radiated in the obtained adhesive layer 3, and the energy ray is irradiated. After that, the adhesion to the substrate 2 is sufficiently improved.

(3) Other ingredients

The adhesive composition forming the adhesive layer 3 in this embodiment may contain various additives such as a photopolymerization initiator, an antistatic agent, a coloring material such as a dye and a pigment, a flame retardant, and a filler, in addition to the above components.

Examples of the photopolymerization initiator include a benzoin compound and benzene Ethyl ketone compounds, fluorenyl phosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxy compounds, and other photoinitiators; amines and quinones; and other photosensitizers. Specific examples include 1-hydroxycyclohexylphenyl Ketones, benzoin, benzoin methyl ether, benzoin ether, benzoin isopropyl ether, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, bibenzyl, biacetamidine, β-chlorine Anthraquinone, 2,4,6-trimethylbenzylidene diphenylphosphine oxide, etc. When ultraviolet rays are used as the energy rays, the irradiation time and the irradiation amount can be reduced by blending a photopolymerization initiator.

(4) Thickness

The thickness of the adhesive layer 3 is not limited as long as it can function properly in the process of using the adhesive sheet 1. For example, when the adhesive sheet 1 is used as a dicing sheet and a back-side abrasive sheet, the thickness of the adhesive layer 3 is preferably 1 to 80 μm, more preferably 3 to 60 μm, and still more preferably 5 to 35 μm. When the thickness of the adhesive layer 3 is 1 μm or more, it is possible to suppress variations in the adhesive force of the adhesive sheet 1 to be small. In addition, if the thickness of the adhesive layer 3 is 80 μm or less, when the adhesive layer 3 is formed by applying the coating composition, it can avoid excessive time consuming during drying.

3． Release sheet

The pressure-sensitive adhesive sheet 1 of the present embodiment can protect the pressure-sensitive adhesive layer 3 before the pressure-sensitive adhesive layer 3 is attached to the adherend, on the surface of the pressure-sensitive adhesive layer 3 opposite to the surface of the substrate 2 side. Laminated release sheet. The configuration of the release sheet is arbitrary, and examples are those in which the film itself has a release property from the protective film forming film, and a release treatment of the plastic film by a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene. . As the release agent, a silicone-based, fluorine-based, long-chain alkyl-based, or the like can be used. Among these, a silicone-based one which is inexpensive and can obtain stable performance is preferred. The thickness of the release sheet is not particularly limited, but is usually about 20 to 250 μm.

4． Physical properties (adhesive force)

The adhesive force of the adhesive sheet 1 before and after the energy ray is irradiated depends on the purpose of the adhesive sheet 1. For example, when the adhesive sheet 1 is used as a cutting sheet or a back-side abrasive sheet, Adhesion is preferably 500 ~ 30000mN / 25mm, especially 750 ~ 22000mN / 25mm, and 1000 ~ 18000mN / 25mm is even more preferable. The adhesive force before irradiation with energy rays is within the above-mentioned range, it is possible to firmly hold the workpiece during processing, and to suppress the occurrence of wafer scattering.

On the other hand, adhesion of the adhesive sheet 1 after irradiation with energy rays The force is preferably 10 ~ 400mN / 25mm, especially 20 ~ 115mN / 25mm, and 30 ~ 80mN / 25mm is more preferable. When the adhesive force after irradiating the energy rays is within the above range, it is easy to separate the processed workpiece or the wafer obtained by processing the workpiece from the adhesive sheet 1.

In addition, a silicon mirror wafer was used as an adherend, a load of 1 kg was applied to attach the adhesive sheet, and it was left to stand in an atmosphere of 23 ° C. and 50% RH for 20 minutes, followed by a 180 ° peeling method according to JIS Z0237: 2000 The adhesive force (mN / 25mm) was measured and used as the adhesive force before irradiation with energy rays. After the adhesive sheet was attached to the adherend under the same conditions as above, it was left for 20 minutes in an atmosphere of 23 ° C. and 50% RH, and then irradiated from the substrate side of the adhesive sheet in a nitrogen atmosphere (illuminance 230 mW). / cm ² , light quantity 190 mJ / cm ² ) After ultraviolet light, the adhesive force measured in the same manner as described above was used as the adhesive force after irradiation with energy rays.

The adhesive force of the adhesive sheet 1 after irradiation with energy rays is The ratio of the adhesion force before radiating energy rays is preferably 0.001 to 0.3, and more preferably 0.01 to 0.2. If the ratio of the adhesion force is within the above range, the balance between the adhesion force before the energy ray irradiation and the adhesion force after the energy ray irradiation becomes good, and it is easy to achieve a higher adhesion force before the energy ray irradiation and after the energy ray irradiation. The lower adhesion.

In the adhesive sheet 1 in this embodiment, the adhesive layer 3 is formed by The aforementioned adhesive composition is formed, so it is easy to control the adhesive force before the energy rays are irradiated, the adhesive force after the energy rays are irradiated, and the ratio thereof within the above range.

5． Manufacturing method of adhesive sheet

The manufacturing method of the adhesive sheet 1 is not specifically limited as long as the adhesive layer 3 which consists of the said adhesive composition can be laminated | stacked on the one side of the base material 2. For example, a coating composition containing the aforementioned adhesive composition and, if necessary, a solvent or a dispersant is prepared, and one surface of the substrate 2 is prepared. The coating composition is applied by a die coater, a curtain coater, a spray coater, a slit coater, a blade coater, etc. to form a coating film, and the coating is applied. The film is dried, whereby the adhesive layer 3 can be formed. The properties of the coating composition are not particularly limited as long as the coating composition can be applied. The composition may include a component for forming the adhesive layer 3 as a solute, or may be contained as a dispersant.

By the above-mentioned drying treatment or by additional heat treatment, The (meth) acrylate polymer (A) in the coating film is subjected to a crosslinking reaction with the epoxy-based crosslinking agent (B) to form a crosslinked structure in the coating film, thereby forming an adhesive layer 3. In order for the crosslinking reaction to proceed sufficiently, usually, after the adhesive layer 3 is formed on the substrate 2 by the method described above, the obtained semiconductor processing sheet is allowed to stand in an environment such as 23 ° C. and a relative humidity of 50%. A few days of health.

As another example of the manufacturing method of the adhesive sheet 1, it may be previously The release surface of the release sheet is coated with a coating composition to form a coating film, and dried to form a laminated body composed of the adhesive layer 3 and a release sheet, and the laminated body of the adhesive layer 3 is formed. A surface opposite to the surface on the release sheet side was adhered to the base material 2 to obtain a laminated body of the adhesive sheet 1 and the release sheet. The release sheet in the laminated body may be peeled as a process material, or the adhesive layer 3 may be protected before the adherend such as a semiconductor package is attached.

6. How to use the adhesive sheet

Hereinafter, a method of using the adhesive sheet 1 of this embodiment as a dicing sheet will be described.

First, the pressure-sensitive adhesive sheet 1 of this embodiment is placed on the side of the pressure-sensitive adhesive layer 3 The surface (that is, the surface of the adhesive layer 3 on the side opposite to the substrate 2) is attached to the semiconductor wafer in such a manner as to be in contact with the semiconductor wafer. When sticking to adhesive sheet 1 When there is a release sheet on the surface layer layer on the adhesive layer 3 side, the release sheet may be peeled off to expose the surface on the adhesive layer 3 side and attach the surface to the semiconductor wafer.

Here, the semiconductor wafer with the adhesive sheet 1 may be immersed in a solvent. in. At this time, when the (meth) acrylate copolymer (A) constituting the adhesive layer 3 contains an alkyl (meth) acrylate monomer (A1) having 6 or more carbon atoms in the alkyl group as a constituent monomer In the unit, the adhesive layer 3 is excellent in solvent resistance, so the adhesive layer 3 does not swell or dissolve, and maintains a good layer state and a state of bonding to the semiconductor wafer.

Next, a dicing process is performed to obtain a plurality of semiconductor wafers. Wafer. The adhesive layer 3 in this embodiment has a sufficient degree of adhesion in the dicing process before irradiating energy rays. Therefore, the formed wafer is firmly fixed to the adhesive sheet 1, so that chipping is unlikely to occur during the dicing process.

After the cutting process is completed, the substrate 2 is irradiated from the side Shoot energy rays. As a result, the hardening group of the (meth) acrylate copolymer (A) contained in the adhesive layer 3 undergoes a polymerization reaction to reduce the adhesiveness, and the wafer can be picked up.

As an example, after irradiating energy rays, The expansion process of extending the adhesive sheet 1 is easy to pick up a plurality of wafers arranged close to the adhesive sheet 1. In addition, the expansion process can also be performed before irradiating energy rays.

After the expansion process, the wafers on the adhesive layer 3 are picked up. take. Picking up can be performed by general means such as suction of collets. After the adhesive layer 3 in this embodiment is irradiated with energy rays, the adhesive force is sufficiently reduced, so that the pick-up can be easily performed. Moreover, the adhesive layer 3 in this embodiment After the energy ray is radiated, the adhesiveness to the base material 2 is also excellent. Therefore, during the pick-up described above, the base material 2 and the adhesive layer 3 can be effectively prevented from peeling off and the adhesive layer 3 can be stuck on the wafer side. The picked-up wafer is supplied to a subsequent process such as a transfer process.

The embodiments described above are described in order to facilitate understanding of the present invention. The carrier is not described for limiting the present invention. Therefore, each of the elements disclosed in the above embodiments also includes all design changes and equivalents belonging to the technical scope of the present invention.

For example, another layer may be laminated on the surface of the substrate 2 on the side opposite to the side of the adhesive layer 3 in the adhesive sheet 1.

[Example]

Hereinafter, the present invention will be described in more detail with examples and the like, but the scope of the present invention is not limited to those examples and the like.

[Example 1]

89.5 parts by mass of lauryl acrylate, 10 parts by mass of 2-hydroxyethyl acrylate, and 0.5 parts by mass of acrylic acid were copolymerized to obtain an acrylic copolymer. The reaction amount of the acrylic copolymer and methacryloxyethyl isocyanate (MOI) per 100 g of the MOI of the acrylic copolymer was 12.1 g (2-hydroxyethyl acrylate per 100 mole units of the acrylic copolymer). The reaction was performed so that the ester became 95 mol (95 mol%), thereby obtaining an energy ray-curable (meth) acrylate copolymer (weight average molecular weight: 600,000).

In a solvent, 100 parts by mass of the obtained energy ray-curable (meth) acrylate copolymer (solid content conversion; the same applies hereinafter), and 1-hydroxycyclohexylphenyl ketone (Ciba Specialty) as a photopolymerization initiator Chemicals Inc., IRGACURE 184) 3 parts by mass, as an epoxy resin A polyglycidylamine compound (TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.) of the cross-linking agent was mixed in an amount of 0.1 parts by mass to obtain an adhesive composition (composition for coating).

Silicone peeling on one side of polyethylene terephthalate film The release-treated surface of the release film (SP-PET3811, manufactured by Lintec Corporation) is coated with the coating composition described above so that the thickness after drying becomes 10 μm, and dried (drying conditions: 100 ° C., 1 minute). ) To form an adhesive layer.

Next, prepare a corona-treated polypropylene film (thickness 80 μm) as a substrate, the substrate and the adhesive layer were bonded so that the corona-treated surface of the polypropylene film was in contact with the adhesive layer, thereby obtaining a substrate, an adhesive layer, and a release film. Adhesive sheet.

Here, the compounding of the said adhesive composition is shown in Table 1. Details of abbreviations and the like described in Table 1 are as follows.

[(Meth) acrylate copolymer]

LA: Lauryl Acrylate

HEA: 2-hydroxyethyl acrylate

AAc: Acrylic

BA: n-butyl acrylate

2-EHA: 2-ethylhexyl acrylate

iOA: isooctyl acrylate

[Crosslinking agent]

epoxy: polyglycidylamine-based compound (Mitsubishi Gas Chemical Company, Inc., TETRAD-C)

TDI-TMP: Adduct of toluene diisocyanate and trimethylolpropane triacrylate (manufactured by Toyochem Co., Ltd., BHS8515)

HDI-TMP: adduct of hexamethylene diisocyanate and trimethylolpropane triacrylate (manufactured by Toyochem Co., Ltd., Bxx4773)

[Examples 2 to 12, Comparative Examples 1 to 3]

The ratio of each monomer constituting the (meth) acrylate copolymer, the reaction amount of methacryloxyethyl isocyanate (MOI), and the type and blending amount of the crosslinking agent are changed as shown in Table 1. An adhesive sheet was produced in the same manner as in Example 1. The cross-linking agent-based isocyanate-based cross-linking agent (TDI-TMP or HDI-TMP) used in Comparative Examples 1 to 3.

[Test Example 1] <Adhesion Test>

The adhesive sheets produced in the examples and comparative examples were irradiated from the substrate side of the adhesive sheet (illuminance 230 mW / cm ² , light quantity 190 mJ) using a UV irradiation device (manufactured by Lintec Corporation: RAD-2000m / 12) in a nitrogen atmosphere. / cm ² ) Ultraviolet (UV). After that, the hardened adhesive layer was formed into a checkerboard of 400 grids with a 5 mm vertical and horizontal angle by a cutting tool.

Next, an adhesive tape (cellophane tape manufactured by Nichiban Print Co., Ltd.) was attached to the checkerboard using a rubber roller under an environment of 23 ° C and 50% RH. After attaching, the adhesive tape was rubbed with a metal plate for 1 minute, so that the adhesive tape was fully attached to the checkerboard, and then allowed to stand for 20 minutes. Then, the adhesive tape was peeled off, and the number of checkerboard cells (the number of cells; the number of NGs) where peeling occurred between the adhesive layer of the adhesive sheet and the substrate was counted. The results are shown in Table 2.

[Test Example 2] <Measurement of Adhesion>

The adhesive sheets produced in the examples and comparative examples were cut into a width of 25 mm × a length of 200 mm, and this was used as a test piece. A 1 kg weight was applied to the mirror surface of the silicon mirror wafer (8 inches in diameter and thickness 50 μm) to attach the adhesive sheet, and it was left to stand in an atmosphere of 23 ° C. and 50% RH for 20 minutes. Thereafter, in accordance with JIS Z0237: 2000, a universal tensile tester (TENSILON / UTM-4-100, manufactured by Orientec) was used to measure the adhesive force of the adhesive sheet at a peeling speed of 300 mm / minute and a peeling angle of 180 ° as irradiation. Adhesion before energy rays (mN / 25mm). The results are shown in Table 2.

After the adhesive sheet was attached to a silicon mirror wafer, it was left to stand in an atmosphere of 23 ° C. and 50% RH for 20 minutes. Thereafter, an ultraviolet irradiation device (manufactured by Lintec Corporation: RAD-2000m / 12) was used. irradiating the substrate side from the adhesive sheet under a nitrogen atmosphere (illuminance 230mW / cm ^2, light quantity of 190mJ / cm ²⁾ ultraviolet (UV). About the adhesive sheet after ultraviolet irradiation, the adhesive force was measured as the adhesive force (mN / 25mm) after energy beam irradiation similarly to the above. The results are shown in Table 2.

[Test Example 3] <Solvent Resistance Test>

For the adhesive sheets manufactured in the examples and comparative examples, the mirror surface of a silicon mirror wafer (diameter 8 inches, thickness 50 μm) was applied at a pressure of 0.3 MPa and a speed of 5 mm in an atmosphere of 23 ° C and 50% RH / Sec attaches the adhesive sheet. Then, the ring frame was attached to the peripheral edge portion of the adhesive sheet under the same attaching conditions. The adhesive sheet was cut into a shape along the outer periphery of the ring frame, and this was used as an evaluation sample.

The evaluation sample was immersed in N-methylpyrrolidone (SP value: 11.2 (cal / cm ³ ) ^1/2 ) as a solvent at 80 ° C. for 1 minute. Then, the width (permeation width) of the solvent which penetrated between the silicon mirror wafer and the adhesive layer of the adhesive sheet was measured. The results are shown in Table 2.

As can be seen from Table 2, the adhesive sheet manufactured in the examples is After the energy ray is irradiated, the adhesion between the adhesive layer and the substrate is also excellent. In addition, the adhesive sheet systems produced in Examples 1 to 3 and 7 to 9 are particularly excellent in solvent resistance. On the other hand, the adhesive sheets manufactured in the comparative examples were all those with poor adhesion between the adhesive layer and the substrate after irradiating energy rays.

[Industrial availability]

The adhesive sheet of the present invention is suitably used as a dicing sheet or a back-side polishing sheet for semiconductor wafer processing.

Claims (8)

An adhesive sheet is characterized in that it includes a substrate and an adhesive layer laminated on at least one side of the substrate. The adhesive layer is formed of an adhesive composition, and the adhesive composition contains energy ray-hardenability. (Meth) acrylate copolymer (A) and epoxy-based cross-linking agent (B), the (meth) acrylate copolymer (A) is an acrylic copolymer (AP) and a hardening group-containing compound (A4) It is obtained by reacting, and the acrylic copolymer (AP) is an alkyl (meth) acrylate monomer (A1), a hydroxyl group-containing monomer (A2), and has an ability to react with an epoxy group. A functional group-containing monomer (A3) having a functional group (excluding a hydroxyl group) is copolymerized, and the aforementioned hardening group-containing compound (A4) has a functional group capable of reacting with a hydroxyl group and an energy-ray-curable carbon-carbon double The aforementioned adhesive composition does not include ammonia, a basic amine salt, a primary amine, a secondary amine, a tertiary amine, an amine compound having a plurality of N in a molecule, or a cyclic amine compound. The pressure-sensitive adhesive sheet according to item 1 of the scope of patent application, wherein the (meth) acrylate copolymer (A) contains 50% of the hydroxyl groups of the (meth) acrylate copolymer (A). The hardening group derived from the said hardening group containing compound (A4) is mol% or more. The pressure-sensitive adhesive sheet according to item 1 of the scope of patent application, wherein the quality of the structural portion derived from the aforementioned (meth) acrylic acid alkyl ester monomer (A1) is equal to that of the aforementioned (meth) acrylic acid ester copolymer (A) The proportion of the total mass is 50 to 99% by mass. The pressure-sensitive adhesive sheet according to item 1 of the scope of patent application, wherein the number of carbon atoms in the alkyl group of the alkyl (meth) acrylate monomer (A1) is 6 or more. The adhesive sheet according to item 1 of the scope of patent application, wherein the mass of the structural portion derived from the functional group-containing monomer (A3) is in the mass of the entire (meth) acrylate copolymer (A) The proportion is 0.1 to 5 mass%. The adhesive sheet according to item 1 of the scope of patent application, wherein the proportion of the mass of the structural portion derived from the aforementioned hydroxyl-containing monomer (A2) to the entire mass of the aforementioned acrylic copolymer (AP) is 1 ~ 25% by mass. The pressure-sensitive adhesive sheet according to item 1 of the scope of patent application, wherein the base material is a polyolefin-based film, and the polyolefin-based film includes only olefin as a polymerization monomer. The adhesive sheet according to item 1 of the scope of patent application, wherein the aforementioned adhesive sheet is an adhesive sheet for semiconductor processing.