TWI732895B - Adhesive sheet for semiconductor processing - Google Patents

Abstract

The present invention relates to an adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing provided with a substrate, and an adhesive layer formed on the substrate and formed by an adhesive composition, wherein the adhesive composition Containing polymer (A) with reactive functional group (A1), polymer (B) with reactive functional group (B1) and energy ray polymerizable group (B2) different from reactive functional group (A1) , Crosslinking agent (C) that reacts with reactive functional group (A1), and crosslinking agent (D) that reacts with reactive functional group (B1).

Description

Adhesive sheet for semiconductor processing

The present invention relates to an adhesive sheet for semiconductor processing, and more particularly to an adhesive sheet for protecting the surface of a semiconductor wafer used to protect the surface of a semiconductor wafer with bumps.

The thinning, miniaturization, and multi-functionalization of information terminal equipment are rapidly progressing. The semiconductor devices mounted on these devices are also required to be thinner and denser, and thinner semiconductor wafers are also desired. In the past, in order to meet this requirement, back grinding and thinning of semiconductor wafers have been performed. In addition, in recent years, semiconductor wafers have formed bumps made of solder with a height of about tens to hundreds of μm on the surface of the wafer. When such bumped semiconductor wafers are ground on the back side, in order to protect the bumped portion, a surface protection sheet is attached to the surface of the bumped wafer.

As a surface protection sheet, as disclosed in Patent Document 1, it is known to use an adhesive sheet in which an intermediate layer and an adhesive layer are sequentially provided on a substrate. In Patent Document 1, a customary adhesive such as an acrylic adhesive, a silicone adhesive, and a rubber adhesive is used for the adhesive layer. In addition, it has been shown that a cross-linking agent can also be blended in the adhesive to introduce a cross-linked structure.

In addition, Patent Document 1 also discloses that an energy ray-curable oligomer is formulated in an adhesive, or a carbon-carbon double bond is introduced into a polymer constituting the adhesive to make the adhesive become energy ray-curable. The surface protection sheet uses an energy ray-curable adhesive, and the adhesive force of the adhesive layer is reduced by the irradiation of the energy ray, so it is easy to peel off from the semiconductor wafer after use.

In addition, conventionally, ultra-high-strength gels having a double network structure have been known. The ultra-high-strength gel system is shown in Non-Patent Document 1. Poly(2-acrylamide-2-methylpropanesulfonic acid) is polymerized to obtain a gel (PAMPS gel), and the PAMPS gel is immersed in acrylic acid. After the amine monomer solution, it is obtained by polymerizing acrylamide inside the PAMPS gel.

[Prior Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent No. 4367769

Non-Patent Document 1: The creation of ultra-high-strength double-network gel and its high-strength mechanism, Collected Papers on Polymers, Vol.65,No.12,(2008)pp.707-715

In recent years, along with the higher density and miniaturization of semiconductor devices, the bump height has tended to increase. However, for semiconductor wafers with larger bump heights, adhesive residue (paste residue) is likely to occur on the bumps when the surface protection sheet is peeled off. Although the paste residue tends to be reduced due to the energy ray curability of the adhesive, in recent years, it is required to reduce the contamination of semiconductor wafers. Only by making the energy ray curability, the paste residue cannot be reduced to the desired level. degree.

In addition, in Non-Patent Document 1, there is no attempt to apply an ultra-high-strength gel having a double network structure to an adhesive or to change it to energy ray curability.

The present invention has been completed in view of the above circumstances, and the subject of the present invention is to provide an adhesive sheet for semiconductor processing that does not easily produce paste residue on the surface of a workpiece such as a semiconductor wafer during peeling.

As a result of active review, the inventors found that by blending two types of polymers in the adhesive composition constituting the adhesive layer, individual polymers are cross-linked through different cross-links, and one type of polymer is made into energy ray hardening. It is possible to solve the above-mentioned problems and complete the following invention. That is, the present invention provides the following (1) to (10) adhesive sheets for semiconductor processing.

(1) An adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing provided with a substrate and an adhesive layer formed on one side of the substrate and formed by an adhesive composition, characterized by The aforementioned adhesive composition contains a polymer (A) having a reactive functional group (A1), a reactive functional group (B1) and an energy ray polymerizable group (B2) that are different from the reactive functional group (A1) The polymer (B), the crosslinking agent (C) that reacts with the reactive functional group (A1), and the crosslinking agent (D) that reacts with the reactive functional group (B1).

(2) The adhesive sheet for semiconductor processing according to (1) above, wherein the weight average molecular weight of the polymer (A) is higher than the weight average molecular weight of the polymer (B).

(3) The adhesive sheet for semiconductor processing according to (1) or (2) above, wherein the polymer (A) and the polymer (B) are both acrylic polymers.

(4) The adhesive sheet for semiconductor processing according to the above (3), wherein the weight average molecular weight of the acrylic polymer constituting the polymer (A) is higher than the weight average molecular weight of the acrylic polymer constituting the polymer (B), and the difference is More than 200,000.

(5) The adhesive sheet for semiconductor processing according to the above (4), wherein the weight average molecular weight of the acrylic polymer constituting the polymer (A) is 300,000 to 1,000,000, and the weight of the acrylic polymer constituting the polymer (B) The average molecular weight is 5,000 to 100,000.

(6) The adhesive sheet for semiconductor processing according to any one of the above (3) to (5), wherein the acrylic polymer constituting the polymer (A) contains a single functional group derived from the reactive functional group (A1) The structural unit of the body (a1) and the acrylic copolymer (A') of the structural unit derived from the alkyl (meth)acrylate (a2).

(7) The adhesive sheet for semiconductor processing according to any one of (3) to (6) above, wherein the acrylic polymer constituting the polymer (B) is an energy-containing polymer having an energy-ray polymerizable group (B2) The linear polymerizable compound (S) and the constitutional unit derived from the functional monomer (b1) having the reactive functional group (B1), and the acrylic acid which is derived from the constitutional unit of the alkyl (meth)acrylate (b2) The reactant obtained by partially reacting a part of the reactive functional group (B1) of the polymer (B').

(8) The adhesive sheet for semiconductor processing according to any one of claims 1 to 7, wherein the reactive functional group (A1) is a carboxyl group, and the reactive functional group (B1) is a hydroxyl group.

(9) The adhesive sheet for semiconductor processing according to the above (8), wherein the crosslinking agent (C) is an epoxy-based crosslinking agent, and the crosslinking agent (D) is an isocyanate-based crosslinking agent.

(10) The adhesive sheet for semiconductor processing according to any one of (1) to (9) above, wherein in the adhesive composition, the content of the crosslinking agent (D) is more than that of the crosslinking agent on a mass basis The content of (C), and the content of the crosslinking agent (D) of the adhesive composition is 2 to 20 parts by mass relative to 100 parts by mass of the polymer (B).

The present invention can provide an adhesive sheet for semiconductor processing which is unlikely to produce paste residue on the surface of a workpiece during peeling.

Fig. 1 is a stress-strain curve of the adhesive layer after hardening of the energy ray of Example 1 through a cyclic tensile test.

Fig. 2 is a stress-strain curve of the adhesive layer of Example 1 before hardening by a cyclic tensile test.

Fig. 3 shows the stress-strain curve of the adhesive layer after the energy ray hardening of Comparative Example 1 is subjected to a cyclic tensile test.

In the following description, "weight average molecular weight (Mw)" is a value measured in terms of polystyrene by a gel permeation chromatography (GPC) method, and specifically is a value measured based on the method described in the examples.

In addition, in the description in this specification, for example, "(meth)acrylate" is used in terms of both "acrylate" and "methacrylate", and the same applies to other similar terms.

Hereinafter, the present invention will be explained in more detail using embodiments.

The adhesive sheet for semiconductor processing of the present invention (hereinafter also referred to as "adhesive sheet") includes a substrate and an adhesive layer provided on the other surface of the substrate. And the adhesive sheet can also have an intermediate layer between the substrate and the adhesive layer. The adhesive sheet may also be composed of two or three layers as described above, and other layers may be further provided. For example, a release material may be further provided on the adhesive layer.

Hereinafter, each member constituting the adhesive sheet will be described in detail.

<Substrate>

The substrate used in the adhesive sheet is not particularly limited, but is preferably a resin film. Since the resin film generates less dust than paper or non-woven fabrics, it is suitable for processing components of electronic parts and is easy to obtain. The substrate may be a single-layer film formed by one resin film, or a multilayer film formed by laminating plural resin films.

Examples of resin films used as substrates include polyolefin-based films, vinyl halide polymer-based films, acrylic resin-based films, rubber-based films, cellulose-based films, polyester-based films, polycarbonate-based films, and polystyrene. Film, polyphenylene sulfide film, cycloolefin polymer film, etc.

Among them, based on the viewpoint that the wafer can be held stably when the wafer is ground to an extremely thin thickness, and the viewpoint of a film with high thickness precision, a polyester-based film is preferred. Among the polyester-based films, it is based on the ease of obtaining and thickness. From the viewpoint of high accuracy, a polyethylene terephthalate film is more preferable.

In addition, the thickness of the substrate is not particularly limited, but is preferably from 10 to 200 μm, more preferably from 25 to 150 μm, and still more preferably from 25 to 100 μm.

In addition, from the viewpoint of improving the adhesion of the substrate to the adhesive layer or the intermediate layer, it can also be used on the surface of the resin film and further provided with an easy-adhesive layer. Furthermore, the base material used in the present invention may also contain fillers, colorants, antistatic agents, antioxidants, organic lubricants, catalysts, etc., within a range that does not impair the effects of the present invention. In addition, the base material may be transparent, or may be colored as desired, but it is preferably one that can penetrate the energy ray to a sufficient degree to harden the adhesive layer.

<Adhesive layer>

The adhesive layer is provided on the substrate, or when an intermediate layer is provided, it is the one provided on the intermediate layer. The adhesive layer is formed by the adhesive composition. The adhesive composition contains a polymer (A) and a polymer (B), and a crosslinking agent (C) and a crosslinking agent (D). Hereinafter, each component will be described in detail.

[Polymer (A), (B)]

The polymer (A) has a reactive functional group (A1). In addition, the polymer (B) has a reactive functional group (B1) and an energy ray polymerizable group (B2) that are different from the reactive functional group (A1). The reactive functional group (A1) of the polymer (A) is one that does not react with the crosslinking agent (D), but preferentially reacts with the crosslinking agent (C). In addition, the reactive functional group (B1) of the polymer (B) does not react with the crosslinking agent (C), but preferentially reacts with the crosslinking agent (D).

The reactive functional group (A1) and the reactive functional group (B1) are not particularly limited, and only need to be selected from a hydroxyl group, a carboxyl group, an amino group, an epoxy group, etc., and among these, a carboxyl group and a hydroxyl group are preferred.

Furthermore, it is more preferable that any one of the reactive functional group (A1) and the reactive functional group (B1) is a carboxyl group, and the other is a hydroxyl group. Thereby, the polymer (A) reacts with the crosslinking agent (C), and the polymer (B) reacts with the crosslinking agent (D), and individual mesh structures are easily formed.

Here, the reactive functional group (A1) may be a hydroxyl group and the reactive functional group (B1) may be a carboxyl group, but more preferably the reactive functional group (A1) is a carboxyl group and the reactive functional group (B1) is a hydroxyl group. When the reactive functional group (B1) of the polymer (B) is a hydroxyl group, it easily reacts with the energy-beam polymerizable group-containing compound (S) described later.

The polymer (A) is a compound that does not have an energy ray polymerizable group, and therefore, is a non-energy ray curable compound that does not harden even if it is irradiated with energy rays. On the other hand, since the polymer (B) has an energy ray polymerizable group (B2), it is an energy ray curable compound that is cured by irradiation with energy rays. When the adhesive layer formed of the adhesive composition is irradiated with energy rays, the polymer (B) hardens and the adhesive force becomes low.

In addition, the term "energy rays" means those having energy quantum in electromagnetic waves or charged particle beams, and examples thereof include ultraviolet rays, electron beams, and the like. Among these, it is preferable to use ultraviolet rays to harden the adhesive layer.

In addition, examples of the energy-beam polymerizable group (B2) include those having carbon-carbon double bonds such as (meth)acryloyl, vinyl, and allyl groups, and among these, (meth)acryloyl groups are preferred. .

By making the polymer (A) have a reactive functional group (A1), the polymer (B) has a reactive functional group (B1) different from the reactive functional group (A1), and the crosslinking agent (C ) Crosslink the polymer (A), and crosslink the polymer (B) with a crosslinking agent (D) different from the crosslinking agent (C). Therefore, in the adhesive layer, a three-dimensional mesh structure composed of the polymer (A) and the crosslinking agent (C) (hereinafter also referred to as the "first mesh") is formed, and the polymer (B) and the crosslinking A three-dimensional mesh structure composed of the combined agent (D) (hereinafter also referred to as "second mesh"). In addition, since the second mesh contains the energy-beam polymerizable group (B2) in the polymer (B), it is presumed that it becomes a denser mesh and a hard and brittle structure by irradiation with energy rays. On the other hand, it is presumed that the first mesh is composed of the polymer (A) and the crosslinking agent (C), and has a softer and easier to stretch structure than the second mesh.

After the adhesive layer is irradiated with energy rays, as described above, the rigid second mesh is incorporated into the soft first mesh to form a so-called double network. Therefore, the breaking properties of the adhesive layer after energy ray irradiation, such as breaking strength, breaking elongation, breaking energy, etc., tend to become good. When the adhesive sheet is peeled from a workpiece such as a semiconductor wafer, paste residue is not likely to occur on the workpiece.

The polymer (A) and the polymer (B) are adhesive components (adhesive resins) that make the adhesive layer exhibit adhesive, for example, selected from acrylic polymers, urethane polymers, rubber-based polymers, and Polyolefin. The polymer (A) and the polymer (B) are preferably selected from acrylic polymers and urethane polymers, and more preferably acrylic polymers.

As the polymer (A) and the polymer (B), it is preferable to use polymers of the same kind from the viewpoint of compatibility and the like. That is, when the polymer (A) is an acrylic polymer, it is preferable that the polymer (B) is also an acrylic polymer. Moreover, when the polymer (A) is a urethane polymer, it is preferable that the polymer (B) is also a urethane polymer.

In the adhesive layer, when the weight average molecular weight of the polymer (A) is high, the first mesh tends to become a softer and stretched structure. On the other hand, when the weight average molecular weight of the polymer (B) is low, the second mesh Eyes tend to become harder and brittle structures. Furthermore, the second mesh is easy to enter the first mesh, and it is easy to form a dual network. Based on these viewpoints, it is preferable that the weight average molecular weight of the polymer (A) is higher than the weight average molecular weight of the polymer (B).

In addition, the content of the polymer (B) in the adhesive composition is preferably 10-100 parts by mass, more preferably 20-80 parts by mass, and still more preferably 30, relative to 100 parts by mass of the polymer (A). ~70 parts by mass.

By setting the content of the polymer (B) to be at least the above lower limit value, it is possible to impart appropriate energy ray curability to the adhesive layer. In addition, by setting the content within the above range, the coating properties of the adhesive composition, the film-forming properties of the adhesive layer, and the like tend to become good. Furthermore, the first mesh and the second mesh are formed in a well-balanced manner, and the fracture characteristics of the adhesive layer tend to become good.

In addition, in the adhesive composition, the polymer (A) and the polymer (B) are preferably the main components. The total content of the main component polymer (A) and polymer (B) is 50% by mass or more based on the total amount of the adhesive composition (solid content basis), and more preferably 70 to 98% by mass, and More preferably, it is 80 to 95% by mass. In addition, in the present invention, the term “solid content” means all components other than the organic solvent, and includes those that are liquid at room temperature (25°C).

(Acrylic polymer)

Hereinafter, the case where each of the above-mentioned polymer (A) and polymer (B) is an acrylic polymer will be described in more detail.

The acrylic polymer constituting the polymer (A) is a polymer containing a structural unit derived from (meth)acrylate, and preferably contains a functional group monomer (a1) derived from a reactive functional group (A1) (hereinafter Sometimes referred to as "functional monomer (a1)"), the acrylic copolymer (A'), which is a structural unit, preferably contains a structural unit derived from the functional monomer (a1) and an alkyl (meth)acrylate (meth)acrylate ( a2) Acrylic copolymer (A') as a constituent unit. When the polymer (A) contains the structural unit derived from the alkyl (meth)acrylate (a2), it is easy to make the adhesiveness of the adhesive layer good.

The functional group monomer (a1) is exemplified by a monomer having the above-mentioned reactive functional group (A1), and is preferably a carboxyl group-containing monomer. Examples of carboxyl group-containing monomers include carboxylic acids having ethylenically unsaturated bonds such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These can be used individually by 1 type, and can also be used in combination of 2 or more types. Among these, acrylic acid and methacrylic acid are preferred, and acrylic acid is more preferred.

The content of the structural unit derived from the functional monomer (a1) (for example, a carboxyl group-containing monomer), based on the acrylic copolymer (A'), is preferably 0.5 to 15% by mass, more preferably 1 to 8% by mass, It is more preferably 1.5 to 5 mass%. When the content of the functional group monomer (a1) such as the carboxyl group-containing monomer is within the above range, it is easy to impart an appropriate adhesive force to the adhesive layer. Furthermore, by cross-linking with the cross-linking agent (C), the first mesh can be formed better.

The alkyl (meth)acrylate (a2) is exemplified by alkyl (meth)acrylate having 1 to 20 carbon atoms in the alkyl group.

Examples of alkyl (meth)acrylates having 1 to 20 carbon atoms in the alkyl group include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and (meth)acrylate. N-Butyl acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate Esters, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, etc. These may be used individually by 1 type, and may be used in combination of 2 or more types.

Among the above, based on the viewpoint of adequately exerting adhesiveness, alkyl (meth)acrylate having an alkyl group of 1 to 8 carbon atoms is preferred, and (methyl) having an alkyl group of 4 to 8 carbon atoms is more preferred. Alkyl acrylate (hereinafter sometimes referred to as "monomer (α)"). Specifically as the monomer (α), 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate are preferred, and n-butyl (meth)acrylate is more preferred.

The content of the constituent units derived from the alkyl (meth)acrylate (a2), based on the acrylic copolymer (A'), is preferably from 50 to 99.5% by mass, more preferably from 60 to 99% by mass, and still more preferably 70-98.5 mass%.

In addition, as the alkyl (meth)acrylate (a2), it is more preferable to use the above-mentioned alkyl (meth)acrylate having 4 to 8 carbon atoms, that is, the monomer (α), but it is also All of the alkyl (meth)acrylate (a2) contained in the acrylic copolymer (A') may be the monomer (α), or part of it may be the monomer (α).

Specifically, the monomer (α) is preferably from 70 to 100% by mass, more preferably from 80 to 100% by mass, and more preferably from 90 to 100 based on the total amount of the alkyl (meth)acrylate (a2). quality%.

The acrylic copolymer (A') used in the polymer (A) may be a copolymer of the functional monomer (a1) and the alkyl (meth)acrylate (a2), or may be the component (a1), ( a2) Copolymer of the component and the monomer (a3) other than the (a1) component and (a2) component.

The other monomer (a3) means a copolymerizable monomer other than the component (a1) and component (a2). Specifically, it is a (meth)acrylic ring with a cycloalkyl group having 3 to 20 carbon atoms. Alkyl esters, benzyl (meth)acrylate, isobornyl (meth)acrylate, and other (meth)acrylates having a cyclic skeleton; vinyl ester compounds such as vinyl acetate and vinyl propionate; ethylene, Alkenes such as propylene and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene-based monomers such as styrene and α-methylstyrene; of butadiene, isoprene, chloroprene, etc. Diene monomers; nitrile monomers such as acrylonitrile and methacrylonitrile.

The other monomer (a3) may be used alone in the acrylic copolymer (A'), or two or more of them may be used in combination.

The acrylic polymer constituting the polymer (B) is a polymer containing a structural unit derived from (meth)acrylate, and it is preferably an energy-ray polymerizable group-containing compound (S) having an energy-ray polymerizable group (B2) It is obtained by reacting with an acrylic copolymer (B') containing a structural unit derived from a functional monomer (b1) having a reactive functional group (B1) (hereinafter sometimes referred to as "functional monomer (b1)") Reactant. The energy-beam polymerizable group-containing compound (S) is a part of the reactive functional group (B1) of the acrylic copolymer (B'). Furthermore, the acrylic copolymer (B') more preferably further contains a structural unit derived from the alkyl (meth)acrylate (b2).

That is, the acrylic polymer constituting the polymer (B) is preferably an energy ray polymerizable group-containing compound (S) having an energy ray polymerizable group (B2) and a functional group derived from a reactive functional group (B1) The constituent unit of the monomer (b1) is a reactant obtained by partially reacting a part of the reactive functional group (B1) of the acrylic copolymer (B') derived from the constituent unit of the alkyl (meth)acrylate (b2).

The functional group monomer (b1) is a monomer having the above-mentioned reactive functional group (B1), and a hydroxyl group-containing monomer is preferably exemplified.

Examples of hydroxyl-containing monomers include, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate Ester, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and hydroxyalkyl (meth)acrylates. Among them, from the viewpoint of the reactivity with the crosslinking agent (D) and the energy-beam polymerizable group-containing compound (S) and the copolymerizability with other monomers, 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, more preferably 2-hydroxyethyl (meth)acrylate.

In the acrylic copolymer (B') used to form the polymer (B), the content of constituent units derived from the functional monomer (b1) (for example, hydroxyl-containing monomer) is calculated on the basis of the acrylic copolymer (B'). It is preferably 10 to 45% by mass, more preferably 15 to 40% by mass, and still more preferably 20 to 35% by mass. When the content of the functional group monomer (b1) such as a hydroxyl group-containing monomer is within the above range, it is easy to impart an appropriate adhesive force to the adhesive layer. Furthermore, by cross-linking with the cross-linking agent (D), a three-dimensional mesh structure formed by the second mesh can be better formed. Furthermore, by reacting the energy ray polymerizable group-containing compound (S) with the reactive functional group (B1), an appropriate amount of energy ray polymerizable group (B2) can be introduced into the polymer (B).

Specific examples of (meth)acrylic acid alkyl ester (b2) are those that are the same as the above-mentioned (a2) component options, and these can be used alone or in combination of two or more. In addition, as with the component (a2), an alkyl (meth)acrylate having 1 to 8 carbon atoms is preferred, and the monomer (α) is more preferably used. The preferred compound as the monomer (α) is also preferably n-butyl (meth)acrylate.

The content of the alkyl (meth)acrylate (b2), based on the acrylic copolymer (B'), is preferably from 50 to 90% by mass, more preferably from 60 to 85% by mass, and even more preferably from 65 to 80 quality%.

In addition, the alkyl (meth)acrylate (b2) is also the same as the component (a2), and the monomer (α) is preferably used, but it may also be the alkyl (meth)acrylate contained in the acrylic copolymer (B') All esters (b2) are monomers (α), and some of them may be monomers (α). In addition, the details of the content are the same as those described in the above-mentioned polymer (A).

The acrylic copolymer (B') may be a copolymer of functional monomer (b1) and alkyl (meth)acrylate (b2), but may also be (b1) component, (b2) component and these (b1) ) Component and copolymer of monomer (b3) other than component (b2). The other monomer (b3) means a copolymerizable monomer other than the above-mentioned (b1) component and (b2) component. Specifically, it can be appropriately selected and used from those listed as the monomer (a3).

(Containing energy-ray polymerizable compound (S))

The energy ray polymerizable group-containing compound (S) has an energy ray polymerizable group (B2) and a functional group (B3) capable of reacting with the reactive functional group (B1) (hereinafter sometimes referred to as "functional group (B3)") . The functional group (B3) may be a functional group capable of reacting with the reactive functional group (B1), but examples thereof include an isocyanate group, an epoxy group, and a carboxyl group.

In addition, as described above, if the reactive functional group (B1) is a hydroxyl group, the functional group (B3) contained in the energy ray polymerizable group-containing compound (S) is preferably an isocyanate group. Moreover, if the reactive functional group (B1) is a carboxyl group, the functional group (B3) is preferably an epoxy group. Furthermore, if the reactive functional group (B1) is an epoxy group, the functional group (B3) is preferably a carboxyl group.

Among these, it is more preferable that the reactive functional group (B1) is a hydroxyl group and the functional group (B3) is an isocyanate group from the viewpoint of reactivity and the like.

The preferable aspect of the energy ray polymerizable group (B2) is as described above. Therefore, as the energy ray polymerizable group-containing compound (S), a compound having an isocyanate group and a (meth)acryloyl group is preferred.

Specific examples of the energy-ray polymerizable group-containing compound (S) are 2-isocyanatoethyl (meth)acrylate, isocyanatopropyl (meth)acrylate, 1,1-(bisacryloxy) Compounds having isocyanate groups and (meth)acrylic groups such as methyl) ethyl esters; compounds having epoxy groups and (meth)acrylic groups such as glycidyl (meth)acrylate, these Among them, 2-isocyanatoethyl (meth)acrylate is preferred.

Here, a part of the reactive functional group (B1) possessed by the acrylic copolymer (B') reacts with the energy ray polymerizable group-containing compound (S). Therefore, in the polymer (B), the reactive functional group (B1) that has not reacted with the energy ray polymerizable group-containing compound (S) remains, whereby the polymer (B) has the reactive functional group (B1) and Energy ray polymerizable group (B2) both.

The addition rate of the energy-ray polymerizable group-containing compound (S), relative to the total amount of reactive functional groups (B1) (100 equivalents) of the acrylic copolymer (B'), is preferably 75 to 97 equivalents, more preferably 80 to 95 equivalents, more preferably 85 to 93 equivalents.

The content of the constituent units derived from the functional monomer (b1) is in the above-mentioned preferred range (10~45% by mass, more preferably 15~40% by mass, and more preferably 20~35% by mass), and the addition rate is in this range Within, a certain amount of reactive functional groups (B1) remain in the polymer (B). Therefore, the polymer (B) is appropriately cross-linked by the cross-linking agent (D), and it is easy to adjust the adhesive force of the adhesive layer to an appropriate value. Furthermore, an appropriate amount of energy ray polymerizable group (B2) may be introduced into the polymer (B).

The acrylic copolymer (A') and the acrylic copolymer (B') may be random copolymers or block copolymers.

In addition, the acrylic copolymer (A') and the acrylic copolymer (B') can be produced by polymerizing a mixture of monomers constituting each copolymer by a normal radical polymerization method. The polymerization can use a polymerization initiator as desired, and can be carried out by a solution polymerization method or the like. Examples of polymerization initiators include conventional azo compounds and organic peroxides.

When both the polymer (A) and the polymer (B) are acrylic polymers, it is preferable that the weight average molecular weight of the acrylic polymer constituting the polymer (A) is higher than the weight average molecular weight of the acrylic polymer constituting the polymer (B) , And the difference is more than 200,000. In this way, when the molecular weight difference between the two polymers is increased, it is easy to exhibit the poor characteristics of the first mesh and the second mesh, and it is also easy to form a double network. Therefore, the fracture characteristics become better, and it is easy to reduce the paste residue. From these viewpoints, the above-mentioned weight average molecular weight difference is more preferably 300,000 or more, and more preferably 400,000 or more.

On the other hand, the upper limit of the weight average molecular weight difference is not particularly limited, and the difference is preferably 850,000 or less, more preferably 750,000 or less, and still more preferably 700,000 or less.

In the adhesive composition, the weight average molecular weight of the acrylic polymer constituting the polymer (A) is 300,000 to 1,000,000, and the weight average molecular weight of the acrylic polymer constituting the polymer (B) is 5,000 to 100,000.

Among them, the weight average molecular weight of the acrylic polymer constituting the polymer (A) is more preferably 350,000 to 850,000, and more preferably 400,000 to 750,000.

On the other hand, the weight average molecular weight of the acrylic polymer constituting the polymer (B) is more preferably 15,000 to 90,000, and more preferably 30,000 to 80,000.

By making the weight average molecular weight of the polymer (A) more than the above-mentioned lower limit, the first mesh structure is more flexible and easy to stretch. And it is easy to make the adhesive layer have good film-forming properties, and it is also easy to increase the cohesive force of the adhesive layer, and it is not easy to produce paste residue. On the other hand, if the weight average molecular weight of the polymer (A) is not more than the above upper limit, it is easy to make the coating properties of the adhesive composition and the like good.

In addition, by making the weight average molecular weight of the polymer (B) below the upper limit, the second mesh is likely to have a harder and brittle structure, and it is easy to form a better double network. In addition, by being more than the above lower limit, it is easy to make the cohesive force of the adhesive layer appropriate, and it is difficult to produce paste residue.

(Urethane polymer)

Next, the case where the polymer (A) and the polymer (B) are urethane polymers, respectively, will be described. The urethane polymer used in the polymer (A) and the polymer (B) is a polymer containing at least one of a urethane bond and a urea bond.

The urethane polymer constituting the polymer (A) is one having the above-mentioned reactive functional group (A1), and examples thereof include carboxyl group-containing polyurethane.

In addition, examples of the urethane polymer constituting the polymer (B) are those obtained by reacting the above-mentioned energy-beam polymerizable group (S) with a part of the hydroxyl group of the hydroxyl-containing polyurethane. The hydroxyl-containing polyurethane is preferably one having a hydroxyl group at the terminal. An example of the polyurethane having a hydroxyl group at the terminal is a polyurethane polyol obtained by reacting a polyol with a polyisocyanate compound. As the polyol and polyisocyanate compound, various compounds conventionally used in urethane-based adhesives can be used.

When both polymer (A) and polymer (B) are urethane polymers, it is preferable that the weight average molecular weight of polymer (A) is higher than the weight average molecular weight of polymer (B), and the difference is 25,000 Or more, more preferably 50,000 or more. The upper limit of the weight average molecular weight difference is not particularly limited, but the difference is preferably 230,000 or less, more preferably 120,000 or less.

In addition, the weight average molecular weight of the urethane polymer constituting the polymer (A) is preferably from 30,000 to 250,000, more preferably from 40,000 to 150,000.

In addition, the weight average molecular weight of the urethane polymer constituting the polymer (B) is preferably from 2,000 to 25,000, more preferably from 3,000 to 20,000.

[Crosslinking agent (C), (D)]

The crosslinking agent (C) is a crosslinking agent that reacts with the reactive functional group (A1), and is used to crosslink the polymer (A). In addition, the crosslinking agent (D) is a crosslinking agent that reacts with the reactive functional group (B1), and is used to crosslink the polymer (B).

The crosslinking by the crosslinking agent (C) and the crosslinking agent (D) is usually performed by heating the adhesive composition. That is, as described later, the adhesive composition becomes an adhesive layer cross-linked by the cross-linking agent (C) and the cross-linking agent (D) by being applied as a film and heated.

The cross-linking agent (C) and the cross-linking agent (D) are, for example, selected from isocyanate-based cross-linking agents, epoxy-based cross-linking agents, amine-based cross-linking agents, melamine-based cross-linking agents, and aziridine-based cross-linking agents. , Hydrazine-based cross-linking agent, aldehyde-based cross-linking agent, oxazoline-based cross-linking agent, metal alkyd-based cross-linking agent, metal chelating agent-based cross-linking agent, metal salt-based cross-linking agent and ammonium salt-based cross-linking Agent. A crosslinking agent (C) and a crosslinking agent (D) may be used individually by 1 type from these, respectively, and may use 2 or more types together.

The crosslinking agent (C) is appropriately selected corresponding to the type of the reactive functional group (A1) possessed by the polymer (A), and the crosslinking agent (D) corresponds to the reactive functional group possessed by the polymer (B) The type of (B1) is appropriately selected. That is, as the crosslinking agent (C), it is only necessary to select one that does not react with the reactive functional group (B1) but reacts with the reactive functional group (A1). In addition, as the crosslinking agent (D), it is only necessary to select one that does not react with the reactive functional group (A1) but reacts with the reactive functional group (B1). Therefore, the crosslinking agent (C) and the crosslinking agent (D) are different from each other.

For example, as described above, when the reactive functional group (A1) is a carboxyl group, the crosslinking agent (C) is preferably selected from epoxy-based crosslinking agents and metal chelate-based crosslinking agents, more preferably epoxy-based crosslinking agents Crosslinking agent. In addition, when the reactive functional group (A2) is a hydroxyl group, the crosslinking agent (D) is preferably an isocyanate-based crosslinking agent.

As an epoxy-based crosslinking agent, for example, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m -Xylene diamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine, etc. These can be used individually by 1 type, and can also be used in combination of 2 or more types. In addition, as the epoxy-based crosslinking agent, among these, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane is preferred.

Examples of metal chelate-based crosslinking agents include, for example, the coordination of acetylacetone and ethyl acetate on polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium. Compounds such as ethyl acetate, tris(2,4-glutarate), etc. These can be used individually by 1 type, and can also be used in combination of 2 or more types.

In addition, as an isocyanate-based crosslinking agent, a polyisocyanate compound is exemplified. Specific examples of polyisocyanate compounds include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; isophorone diisocyanate, Alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate. Also, examples are these uret bodies, isocyanurate bodies, and further low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, etc. The adduct of the reactant, etc.

These can be used individually by 1 type, and can also be used in combination of 2 or more types. In addition, among the above, polyol (for example, trimethylolpropane, etc.) adducts of aromatic polyisocyanates such as toluene diisocyanate are preferred.

By suppressing the content of the crosslinking agent (C), it is easy to make the first mesh a soft and stretched structure, and it is easy to reduce the paste residue. Therefore, it is preferable that the content of the crosslinking agent (C) is smaller. Specifically, the content of the crosslinking agent (C) in the adhesive composition also depends on the type and molecular weight of the polymer (A), but it is preferably 0.05 to 5 parts by mass relative to 100 parts by mass of the polymer (A). It is preferably from 0.1 to 3 parts by mass, more preferably from 0.1 to 0.3 parts by mass.

On the other hand, since the adhesive composition contains a large amount of crosslinking agent (D), the second mesh tends to have a hard and brittle structure. Therefore, the content of the cross-linking agent (D) is better, and the content of the cross-linking agent (D) in the adhesive composition is preferably more than the content of the cross-linking agent (C) on a mass basis.

The content of the crosslinking agent (D) in the adhesive composition also depends on the type and molecular weight of the polymer (B), but specifically, it is preferably 2-20 mass parts relative to 100 mass parts of the polymer (B) Parts, preferably 4 to 16 parts by mass, more preferably 5 to 12 parts by mass.

[Photopolymerization initiator (E)]

The adhesive composition preferably contains a photopolymerization initiator (E). Since the adhesive layer contains the photopolymerization initiator (E), the adhesive layer can be easily cured by energy rays such as ultraviolet rays.

As the photopolymerization initiator (E), for example, acetophenone, 2,2-diethoxybenzophenone, 4-methylbenzophenone, 2,4,6-trimethyldiphenyl Methyl ketone, Michler's ketone, benzidine, benzidine methyl ether, benzidine ethyl ether, benzidine isopropyl ether, benzidine isobutyl ether, benzyl diphenyl sulfide, tetramethyl thiuram mono Sulfide, benzyl dimethyl acetal, biphenyl acetal, biacetin, 1-chloroanthraquinone, 2-chloroanthraquinone, 2-ethylanthraquinone, 2,2-dimethoxy-1,2 -Diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinone-1, 2-benzyl 2-Dimethylamino-1-(4-morpholinephenyl)butanone-1, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, diethylthioxanthone , Isopropyl thioxanthone, 2,4,6-trimethylbenzyl diphenyl-phosphine oxide and other low molecular weight polymerization initiators; oligomer {2-hydroxy-2-methyl-1- [4-(1Methylvinyl)phenyl]acetone} and other polymerization initiators for oligomerization. These may be used alone, or two or more of them may be used in combination.

The content of the photopolymerization initiator (E) is preferably from 0.1 to 20 parts by mass, more preferably from 0.5 to 15 parts by mass, with respect to 100 parts by mass of the total amount of polymer (A) and polymer (B), and more Preferably it is 2-12 parts by mass.

In addition, the adhesive layer may also contain adhesion imparting agents, dyes, pigments, deterioration inhibitors, antistatic agents, flame retardants, silane coupling agents, chain transfer agents, plasticizers, The filler, the above-mentioned polymer (A) and the resin component other than the polymer (B), etc. are used as components other than the above.

The thickness of the adhesive layer can be adjusted appropriately according to the bump height of the wafer surface, etc., and the surface condition of the adhesive sheet, but it is preferably 2~150μm, more preferably 5~100μm, and even more preferably 8~ 50μm.

[Fracturing characteristics of the adhesive layer]

The adhesive layer is hardened by irradiating energy rays as described above, and the fracture characteristics after hardening of the energy rays are preferably as follows.

That is, it is preferable that the fracture stress of the adhesive layer after energy ray hardening is 1.5 MPa or more, the elongation at break is 80% or more, and the fracture energy is 1.0 MJ/m ³ or more. When the breaking stress, breaking elongation, and breaking energy are such high values, the breaking strength of the adhesive layer becomes good, and it is difficult to produce paste residue. In addition, from the viewpoint of preventing paste residue, it is more preferable that the fracture stress is 1.8 MPa or more, the elongation at break is 100% or more, the breaking energy is 1.4 MJ/m ³ or more, and the fracture stress is more than 2.0 MPa. The elongation is 180% or more, and the breaking energy is 1.8 MJ/m ³ or more.

In addition, the upper limit is not particularly limited, but it is practically preferable that the breaking stress is 10 MPa or less, the breaking elongation is 400% or less, the breaking energy is 5.0 MJ/m ³ or less, and the breaking stress is more preferably 6 MPa or less, and the breaking elongation is more preferable. It is 300% or less, and the fracture energy is 3.5 MJ/m ³ or less.

In addition, the breaking stress, breaking elongation, and breaking energy mean values measured by a tensile test in accordance with JIS K7127: 1999, and specifically, they are values measured by the method described in the examples described later.

(Hysteresis)

When the adhesive layer after energy ray hardening has the above-mentioned double network, when a certain strain is applied, the second mesh is destroyed. On the other hand, the first mesh remains undamaged. Therefore, when the adhesive layer after energy ray hardening is applied with a certain strain and then strain is applied again, it is caused by the destruction of the second mesh, which makes the stress-strain characteristic different from the initial one. These properties are called hysteresis, but the existence and magnitude of hysteresis can be confirmed by the cyclic tensile test shown below.

That is, the elongation (%) becomes higher each time the number of elongations is increased, and until the sample breaks, repeat the elongation (strain) and release of the sample to perform a cyclic tensile test. As shown in Figure 1, the elongation is made for each elongation stress-strain curve. Therefore, by detecting the maximum value of the stress difference (DSmax) between the curves of the same elongation in a plurality of stress-strain curves, the existence and magnitude of the hysteresis can be confirmed.

Fig. 1 shows the stress-strain curve of the sample after the energy ray hardening of the adhesive layer used in Example 1 described later when subjected to a cyclic tensile test. Figure 1 shows an example where the maximum elongation at each elongation is 50% (first time) and then increased by 50% each time. When the elongation and release are repeated, the sample breaks at 233% at the fifth elongation. Here, Fig. 1 shows the stress-strain curve at each elongation. From the complex stress-strain curve, the maximum value of the stress difference (DSmax) is obtained as shown in Fig. 1. In addition, in the example of Fig. 1, the maximum value of the stress difference (DSmax) is calculated from the curve created twice in succession from the 4th and 5th times, but the maximum value of the stress difference (DSmax) can also be calculated from the discontinuous 2 such as the 3rd and 5th times. Calculate the curve of the second production. In addition, the so-called elongation refers to the length of the increase when the sample is stretched divided by the original length and expressed in %.

If the double network is properly formed, the higher the hysteresis, the more the complex stress-strain curves are separated from each other, and the maximum value of the above-mentioned stress difference (DSmax) becomes larger. Based on the viewpoint of properly forming a double network, the maximum value of the stress difference (DSmax), relative to the stress at break (BS) in the cyclic tensile test, is preferably 20% or more, more preferably 25% or more, and more preferably More than 35%. From the viewpoint of ease of manufacture and the like, the maximum value of the stress difference (DSmax) is preferably at most 90%, more preferably at most 60%.

[Peeling force of adhesive sheet]

Since the adhesive layer is hardened by energy rays, it is relatively soft before the energy ray is irradiated, so that the adhesive layer can easily follow the unevenness formed on the surface of the workpiece. In addition, the adhesive sheet is hardened by irradiating energy rays to reduce the adhesive force and easily peel off from the workpiece.

The adhesive force after the energy ray of the adhesive sheet is irradiated is preferably 1,700mN/25mm or less. When the adhesive sheet is attached to a workpiece with protrusions such as bumps on the surface, the protrusions are usually embedded in the adhesive layer or the adhesive layer and the intermediate layer of the adhesive sheet. Therefore, paste residue is likely to occur when the adhesive sheet is peeled later, but by setting the adhesive force to 1,700 mN/25mm or less, it is easy to prevent such paste residue from occurring. Moreover, the adhesive sheet is also easy to peel off from the workpiece. The adhesive force after the energy ray of the adhesive sheet is irradiated is preferably 50~1,500mN/25mm, more preferably 100~1,300mN/25mm.

In addition, although the adhesive force of the adhesive sheet before irradiation with energy rays is greater than, for example, 1,700 mN/25 mm, it is preferably 1,800 to 20,000 mN/25 mm, and more preferably 1,800 to 9,000 mN/25 mm. When the adhesive force before energy ray irradiation is within this range, the adhesion to the surface of the workpiece becomes better, and the protective performance of the adhesive sheet on the workpiece is improved.

In addition, the adhesive force of the adhesive sheet is measured when the adhesive layer of the adhesive sheet is attached to the silicon mirror wafer at a peeling angle of 180° and a peeling speed of 300mm/min in an environment of 23°C. Specifically, , Is measured by the method described in the following examples.

Adhesive force can be changed by appropriately changing the types of polymer (A) and polymer (B), the blending amount of these polymers, the types of crosslinking agents (C) and crosslinking agents (D), and the types of crosslinking agents The amount of deployment and so on. For example, if the polymer (A) and the polymer (B) are acrylic polymers as described above, it is easy to obtain an adhesive sheet having the above-mentioned adhesive force. Moreover, by increasing the blending amount of the cross-linking agent (C) and the cross-linking agent (D), it is easy to reduce the adhesive force.

In addition, the adhesive force after energy ray irradiation can also be adjusted by the amount of energy ray polymerizable group (B2) and the blending amount of polymer (B). The adhesive force after energy ray irradiation, for example, tends to decrease when the amount of energy ray polymerizable group (B2) contained in the adhesive composition increases, and to increase when it decreases.

<Middle layer>

The adhesive sheet of the present invention can also be provided with an intermediate layer on one side of the substrate. Since the adhesive sheet has an intermediate layer, even when the unevenness of the workpiece surface with bumps and the like is provided on the workpiece, the protrusions can be embedded in the adhesive layer and the intermediate layer. Therefore, the surface of the adhesive sheet opposite to the surface attached to the workpiece can be easily kept flat.

The thickness of the intermediate layer can be adjusted appropriately according to the state of the adhered surface to which the adhesive sheet is attached, but based on the viewpoint that relatively high bumps can also absorb, it is preferably 10 to 600 μm, more preferably 25 to 550 μm, and More preferably, it is 35 to 500 μm.

The intermediate layer is formed of a resin composition for the intermediate layer. In addition, the resin composition for the intermediate layer preferably contains urethane (meth)acrylate (X).

(Urethane (meth)acrylate (X))

The urethane (meth)acrylate (X) is a compound having at least a (meth)acrylic acid group and a urethane bond, and has the property of being polymerized by irradiation with energy rays. The number of (meth)acrylic groups in the urethane (meth)acrylate (X) may be monofunctional, bifunctional, or trifunctional or more, but the resin composition for the intermediate layer preferably contains a monofunctional amine Carboxylate (meth)acrylate. Since monofunctional urethane (meth)acrylate does not participate in the formation of the 3-dimensional mesh structure in the polymerization structure, the intermediate layer is not easy to form a 3-dimensional mesh structure, and it is easy to follow the unevenness of the workpiece surface.

As the urethane (meth)acrylate (X), for example, a compound having a (meth)acryloyl group (x3) and a polyol compound (x1) and a polyisocyanate compound (x2) can be reacted. It is obtained by reaction of terminal isocyanate urethane prepolymer.

Urethane (meth)acrylate (X) can be used 1 type or in combination of 2 or more types.

The polyol compound (x1) used to form the urethane (meth)acrylate (X) is not particularly limited as long as it is a compound having two or more hydroxyl groups. As a specific polyol compound (x1), for example, an alkanediol, a polyether polyol, a polyester polyol, a polycarbonate polyol, etc. are exemplified. Among these, polyether polyols are preferred.

In addition, the polyol compound (x1) may be any of a bifunctional polyol, a trifunctional polyol, or a tetrafunctional or higher polyol, but from the viewpoints of ease of acquisition, wide use, reactivity, etc., it is more It is preferably a bifunctional polyol, more preferably a polyether polyol. As the polyether polyol, preferred specific examples are polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

The polyester polyol is obtained by polycondensing a polyol component and a polyacid component. Examples of the polyol component include various alkanediols (preferably an alkanediol having a carbon number of about 2 to 10) such as ethylene glycol, diethylene glycol, and butanediol, various glycols, and the like.

As the polyacid component used in the production of the polyester polyol, a compound generally known as the polyacid component of polyester can be used. Specifically, examples are aliphatic dibasic acids such as adipic acid and sebacic acid with a carbon number of about 4 to 20, aromatic dibasic acids such as terephthalic acid, and aromatic polybasic acids such as trimellitic acid. , The corresponding acid anhydrides, their derivatives, dimer acids, hydrogenated dimer acids, etc.

The polycarbonate polyol is not particularly limited, and examples include, for example, a reaction product of glycols and alkylene carbonate.

As the polyisocyanate compound (x2), for example, aliphatic polyisocyanate, alicyclic polyisocyanate, aromatic polyisocyanate, etc., more specifically, can be used, for example, as a crosslinking agent (C) and a crosslinking agent (D) Various polyisocyanate compounds exemplified.

In addition, as the compound (x3) having a (meth)acryloyl group, a (meth)acrylate having a hydroxyl group is exemplified. Although it does not specifically limit as a (meth)acrylate which has a hydroxyl group, For example, hydroxyalkyl (meth)acrylate is preferable. As the hydroxyalkyl (meth)acrylate, the same ones as exemplified for the above-mentioned hydroxyl-containing monomer can be used.

The weight average molecular weight of the urethane (meth)acrylate (X) used in the resin composition for the intermediate layer is preferably from 1,000 to 100,000, more preferably from 3,000 to 80,000, and more preferably from 5,000 to 65,000. If the weight average molecular weight is 1,000 or more, the polymer of the urethane (meth)acrylate (X) and the polymerizable monomer (Z) described later can impart moderate hardness to the intermediate layer.

The blending amount of urethane (meth)acrylate (X) in the resin composition for the intermediate layer, based on the total amount of the resin composition for the intermediate layer (based on solid content), is preferably 10 to 70 mass %, more preferably 20 to 70 mass%, still more preferably 25 to 60 mass%, still more preferably 30 to 50 mass%. If the blending amount of urethane (meth)acrylate (X) is within this range, the intermediate layer will easily follow the unevenness of the workpiece surface.

In addition to the above-mentioned urethane (meth)acrylate (X), the resin composition for the intermediate layer preferably further contains, for example, a compound selected from a thiol group-containing compound (Y) and a polymerizable monomer (Z). One or more types in the group, and more preferably contain both of them.

(Thiol group-containing compound (Y))

The thiol group-containing compound (Y) is not particularly limited if it is a compound having at least one thiol group in the molecule, but it is preferably a multifunctional thiol group-containing compound, more preferably a tetrafunctional thiol group-containing compound Base compound.

As specific thiol group-containing compounds (Y), for example, nonyl mercaptan, 1-dodecyl mercaptan, 1,2-ethane dithiol, 1,3-propane dithiol, triazine thiol Alcohol, triazine dithiol, triazine trithiol, 1,2,3-propane trithiol, tetraethylene glycol-bis(3-mercaptopropionate), trimethylolpropane tris(3-mercapto Propionate), pentaerythritol tetra(3-mercaptopropionate), pentaerythritol tetraglycolate, dipentaerythritol hexa(3-mercaptopropionate), tris[(3-mercaptopropionoxy)ethyl]isocyanide Urea ester, 1,4-bis(3-mercaptobutyroxy)butane, pentaerythritol tetra(3-mercaptobutyrate), 1,3,5-tris(3-mercaptobutyroxyethyl) -1,3,5-triazine-2,4,6-(1H,3H,5H)-trione, etc.

Moreover, these thiol group-containing compounds (Y) can be used 1 type or in combination of 2 or more types.

The compounding amount of the thiol group-containing compound (Y) is preferably 1.0 to 4.9 parts by mass relative to the total of 100 parts by mass of the urethane (meth)acrylate (X) and the polymerizable monomer (Z) described later Parts, more preferably 1.5 to 4.8 parts by mass.

(Polymerizable monomer (Z))

The resin composition for the intermediate layer preferably further contains a polymerizable elastomer (Z) from the viewpoint of improving film formability. The polymerizable elastomer (Z) is a polymerizable compound other than the above-mentioned urethane (meth)acrylate (X), and is a compound that can be polymerized by energy ray irradiation. However, the so-called polymerizable monomer (Z) means the one excluding the resin component. The polymerizable monomer (Z) is preferably a compound having at least one (meth)acryloyl group.

In addition, in this specification, the "resin component" means an oligomer or a high molecular weight compound having a repeating unit in the structure, and a compound having a weight average molecular weight of 1,000 or more.

As the polymerizable monomer (Z), for example, alkyl (meth)acrylate having an alkyl group having 1 to 30 carbon atoms, (meth)acrylate having functional groups such as a hydroxyl group, an amino group, an amino group, an epoxy group, etc. (Methyl)acrylate, (meth)acrylate with alicyclic structure, (meth)acrylate with aromatic structure, (meth)acrylate with heterocyclic structure, other vinyl compounds, etc.

Examples of the (meth)acrylate having a functional group include hydroxyalkyl (meth)acrylate and the like. As the hydroxyalkyl (meth)acrylate, the same ones as exemplified for the above-mentioned hydroxyl-containing monomer can be used.

Examples of (meth)acrylates having an alicyclic structure are, for example, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentyl (meth)acrylate, (meth) Dicyclopentenoxy acrylate, cyclohexyl (meth)acrylate, adamantyl (meth)acrylate, etc.

Examples of (meth)acrylates having an aromatic structure include, for example, phenylhydroxypropyl (meth)acrylate, benzyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate Wait.

Examples of (meth)acrylates having a heterocyclic structure include tetrahydrofurfuryl (meth)acrylate, morpholinyl (meth)acrylate, and the like.

These may be used individually by 1 type, and may use 2 or more types together.

As the polymerizable monomer (Z), it is preferable to use (meth)acrylate having at least an alicyclic structure, more preferably (meth)acrylate having a functional group and (meth)acrylic acid having an alicyclic structure As both esters, it is more preferable to use both hydroxyalkyl (meth)acrylate and isobornyl (meth)acrylate.

The blending amount of the polymerizable monomer (Z) in the resin composition for the intermediate layer, based on the total amount of the resin composition for the intermediate layer (solid content basis), is preferably 20 to 80% by mass, more preferably 30 to 80% by mass, more preferably 40 to 75% by mass, still more preferably 50 to 70% by mass. If the blending amount of the polymerizable monomer (Z) is within this range, the part of the polymerizable monomer (Z) in the middle layer is highly mobile, so the middle layer tends to become soft, and the middle layer tends to become softer. Follow the uneven surface of the workpiece.

In addition, the compounding amount of the (meth)acrylate having an alicyclic structure relative to the total amount of the polymerizable monomer (Z) contained in the resin composition for the intermediate layer is preferably 52 to 87% by mass, It is more preferably from 55 to 85% by mass, more preferably from 60 to 80% by mass. When the blending amount of (meth)acrylate with alicyclic structure is within this range, the intermediate layer is easy to follow the unevenness of the workpiece surface.

In addition, based on the same viewpoint, the mass ratio of the urethane (meth)acrylate (X) to the polymerizable monomer (Z) in the resin composition for the intermediate layer [urethane (meth)acrylic acid The ester (X)/polymerizable monomer (Z)] is preferably 20/80 to 60/40, more preferably 30/70 to 50/50, and still more preferably 35/65 to 45/55.

(Photopolymerization initiator)

The resin composition for the intermediate layer preferably further contains a photopolymerization initiator. By containing the photopolymerization initiator, the resin composition for the intermediate layer can be easily cured by energy rays such as ultraviolet rays.

As the photopolymerization initiator, for example, those exemplified for the above-mentioned photopolymerization initiator (E) can be appropriately selected and used. The photopolymerization initiator can be used singly or in combination of two or more kinds.

The compounding amount of the photopolymerization initiator is preferably from 0.05 to 15 parts by mass, more preferably from 0.05 to 15 parts by mass, based on 100 parts by mass of the total of urethane (meth)acrylate (X) and polymerizable monomer (Z) It is 0.1-10 mass parts, more preferably 0.3-5 mass parts.

(Other additives)

The resin composition for the intermediate layer may contain other additives within a range that does not impair the effects of the present invention. Examples of other additives include, for example, crosslinking agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, dyes, and the like. When these additives are blended, the blending amount of other additives is preferably 0.01-6 parts by mass relative to 100 parts by mass of the total of urethane (meth)acrylate (X) and polymerizable monomer (Z) , More preferably 0.1 to 3 parts by mass.

In addition, the resin composition for the intermediate layer may contain urethane (meth)acrylate in addition to urethane (meth)acrylate (X) within a range that does not impair the effects of the present invention. Resin components other than (X).

In addition, the intermediate layer may be formed of a resin composition for an intermediate layer containing other resin components such as an olefin resin instead of the urethane (meth)acrylate (X).

<Peeling material>

As the release material provided on the adhesive layer and the release material used in the steps of the manufacturing method described later, a release sheet subjected to single-sided peeling treatment, a release sheet subjected to double-sided peeling treatment, etc. are used, for example, a base for release material Those who apply a release agent to the material, etc.

Examples of substrates for release materials include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; polypropylene resin, polyethylene Resin, polyolefin resin film, plastic film, etc.

Examples of release agents include rubber-based elastomers such as silicone resins, olefin-based resins, isoprene-based resins, butadiene-based resins, long-chain alkyl-based resins, alkyd resins, and fluorine-based resins. Wait.

In addition, the thickness of the release material is not particularly limited, but it is preferably from 5 to 200 μm, more preferably from 10 to 120 μm.

[Method of manufacturing adhesive sheet]

The manufacturing method of the adhesive sheet of the present invention is not particularly limited, and it can be manufactured according to a conventional method.

The intermediate layer can be formed by, for example, directly coating the resin composition for the intermediate layer on one side of the substrate to form a coating film, then drying and curing treatment as necessary. In addition, the intermediate layer can also be formed by directly coating the resin composition for the intermediate layer on the peeling treatment surface of the release material to form a coating film, then drying as necessary and performing a semi-curing treatment to form a semi-cured layer on the release material. The semi-hardened layer is attached to the base material, and the semi-hardened layer is completely hardened to be formed. At this time, the release material may be appropriately removed before or after the semi-hardened layer is completely hardened. In addition, for the curing of the intermediate layer, it is preferable to irradiate the coating film with energy rays and polymerize and cure it. The energy ray is preferably ultraviolet rays. In addition, when the intermediate layer is formed using an olefin resin, the intermediate layer may be formed by extrusion molding or the like.

In addition, the adhesive layer is preferably formed by applying the adhesive composition, heating the adhesive composition, crosslinking, and drying if necessary. At this time, the adhesive composition can be directly coated on the intermediate layer or the substrate, or it can be coated on the peeling treatment surface of the release material to form an adhesive layer, and then the adhesive layer is pasted on the intermediate layer or the substrate. form. The peeling material arranged on the adhesive layer can also be peeled as needed.

In addition, if the heating temperature and heating time of the adhesive composition are such that the polymer (A) is crosslinked by the crosslinking agent (C), and the polymer (B) is crosslinked by the crosslinking agent (D), As long as the time is required, the heating temperature is usually 80 to 110°C, preferably 90 to 100°C. In addition, the heating time is usually 1 to 5 minutes, preferably 2 to 3 minutes.

When forming the intermediate layer or the adhesive layer, an organic solvent may be further blended into the resin composition or the adhesive composition for the intermediate layer to make a diluent of the resin composition or the adhesive composition for the intermediate layer. Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, and the like.

In addition, these organic solvents may directly use the organic solvent used in the synthesis of each component contained in the resin composition for the intermediate layer or the adhesive composition, or one or more other organic solvents may be added.

The resin composition or adhesive composition for the intermediate layer can be coated by a conventional coating method. Examples of the coating method include, for example, a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die nozzle coating method, a gravure coating method, and the like.

[How to use the adhesive sheet]

The adhesive sheet of the present invention is used for attaching to various workpieces, such as semiconductor wafers and other workpieces, and is preferably attached to the surface of the workpiece having unevenness, protrusions, etc. for use.

Moreover, it is better attached to the surface of a semiconductor wafer, especially attached to the surface of a wafer formed with bumps, and used as an adhesive sheet for protecting the surface of a semiconductor wafer. In addition, the adhesive sheet is better attached to the surface of the semiconductor wafer, and used as a back grinding tape to protect the circuit formed on the surface of the wafer during subsequent back grinding of the wafer. When the adhesive sheet of the present invention has an intermediate layer, even if the wafer surface has a height difference due to bumps, etc., its embedding property is also good, so the protection performance of the wafer surface is good.

The adhesive layer of the present invention is an energy ray hardening type, which is the adhesive sheet attached to the surface of a workpiece such as a semiconductor wafer that is peeled from the surface of the workpiece after being irradiated with energy ray to harden the energy ray. Therefore, the adhesive sheet is peeled off after the adhesive force is reduced, so its peelability is good. In addition, when the adhesive sheet after curing is peeled off as described above, the paste residue is less likely to occur.

In addition, when the adhesive sheet is used for semiconductor wafers, it is not limited to the back grinding sheet, and can also be used for other purposes. For example, the adhesive sheet can also be attached to the back of the wafer and used as a dicing sheet for holding the wafer when cutting the wafer. In this case, the wafer may have through electrodes or the like, or it may have protrusions, bumps, etc., such as bumps on the back surface of the wafer.

Example

Hereinafter, the present invention will be described in further detail based on examples, but the present invention is not limited to these examples.

The measurement method and evaluation method in the present invention are as follows.

[Weight average molecular weight (Mw), number average molecular weight (Mn)]

The gel permeation chromatography device (product name "HLC-8220", manufactured by TOSOH Co., Ltd.) was measured under the following conditions, and the value measured in terms of standard polystyrene was used.

(Measurement conditions)

Column: "TSK protection column HLX-H", "TSK gel GMHXL (×2)", "TSK gel G2000MHXL" (all manufactured by TOSOH Co., Ltd.)

Column temperature: 40℃

Developing solvent: tetrahydrofuran

Flow rate: 1.0mL/min

[Stretching test]

The tensile test was performed by the method shown below in accordance with JIS K7127: 1999.

In addition, the measurement sample used in the tensile test was prepared as follows, and the value obtained by the measurement using the measurement sample was used as the breaking stress, breaking elongation, and breaking energy of the adhesive layer.

(Production of measurement samples)

In the same manner as in Example 1, an adhesive layer with a polyethylene terephthalate (PET) release film (manufactured by LINTEC Co., Ltd., product name "SP-PET381031", thickness 38μm) attached to both sides was prepared (40μm thick). In the same procedure, 5 adhesive layers sandwiched by the same release film were prepared. Next, prepare two adhesive layers exposed by peeling a release film, and laminate the surfaces of the adhesive layers facing each other. This sequence is repeated to laminate 5 adhesive layers to obtain an adhesive layer with a thickness of 200 μm sandwiched between two release films.

The obtained laminate was irradiated with ultraviolet rays under the conditions of ^{an irradiation speed of 15 mm/sec, an illuminance of 220 mW/cm 2} and a light quantity of 500 mJ/cm ² using a UV irradiation device (manufactured by LINTEC Co., Ltd., product name "RAD-2000m/12") To harden the adhesive layer. The obtained hardened material of the adhesive layer was cut into 15mm×140mm to obtain a measurement sample.

(Measurement of breaking stress, breaking elongation and breaking energy of adhesive layer)

A label for stretching the sample was attached to the 20mm portion of the two ends of the measurement sample, and a sample with a measurement target portion of 15mm×100mm was made. For this sample, a tensile testing machine (manufactured by Shimadzu Corporation, trade name "AUTOGRAPH AG-IS 1kN") was used to measure the breaking stress and breaking elongation when measured under the conditions of 100 mm between clamps and a tensile speed of 200 mm/min. . In addition, a stress-strain curve was created when the breaking stress and breaking elongation were measured, and the area under the curve was calculated to obtain the breaking energy.

[Cyclic Tensile Test]

In the same manner as the above-mentioned tensile test, a measurement sample was produced. The tensile test in the cyclic tensile test uses this measurement sample and a tensile testing machine (manufactured by Shimadzu Corporation, trade name "AUTOGRAPH AG-IS 1kN") at a tensile speed of 200 mm/min and a release speed of 600 mm /min conditions.

The cyclic tensile test is to increase the elongation (%) every time the number of elongation is increased, and repeat the elongation (strain) and release of the sample until the sample breaks. At this time, the elongation of each sample is set to increase by a certain% every time since the elongation is 0%. Specifically, the increase in elongation is from any of 3%, 5%, 8%, 10%, 20%, 30%, 50%, 100%, (100+100n)% (n is an integer greater than 1) One, the choice is that the sample breaks after 4 to 6 cycles. That is, for example, when the increase in elongation is 50%, the increase in elongation is 50%, 100%, 150%, 200%, 250%.

In the cyclic tensile test, a stress-strain curve is created for each elongation, and the created stress-strain curve is recorded on the same tracing paper. From the obtained complex stress-strain curve, it is detected that the stress difference between the curves of the same elongation is the largest Value (DSmax).

[Adhesion after energy ray irradiation]

The adhesive sheets of the examples and comparative examples were evenly cut into a width of 25 mm, and were temporarily placed on the silicon mirror wafer of the adherend with the adhesive layer on the side of the adherend. A roller weighing 1 kg is reciprocated once on the temporarily placed adhesive sheet, and a load is applied by the weight of the roller to stick the adhesive sheet to the adherend. After attaching, store at 23°C and 50% relative humidity for 20 minutes. Use a UV irradiation device (manufactured by LINTEC Co., Ltd., product name "RAD-2000m/12"), with illuminance 220mW/cm ² and light intensity 500mJ/ cm ² , the irradiation speed is 15mm/sec, and ultraviolet rays are irradiated from the side of the adhesive sheet. Next, after leaving for 5 minutes in an environment of 23°C and 50% relative humidity, use a tensile tester (manufactured by ORIENTEC, product name "TENSILON") to measure at 23°C and 50% relative humidity at a peel angle of 180 °, the condition of peeling speed 300mm/min, the adhesive force when peeling the adhesive sheet.

[Adhesion before energy ray irradiation]

The measurement was performed in the same manner as above, except that the ultraviolet irradiation and the subsequent 5 minutes of leaving it were omitted.

[Evaluation of paste residue]

Prepare a wafer with a bump height of 250μm, a pitch of 500μm, and a diameter of 300μm as viewed from the top of the spherical bump (manufactured by Waltz, 8-inch wafer, bump specifications Sn/Ag/Cu=96.5/3/0.5 mass%, The surface material of the wafer is SiO ₂ ) as the adherend.

The adhesive sheets produced in the Examples and Comparative Examples were formed facing each other with the adhesive layer of the adhesive sheet and the bumps of the wafer facing each other, using a laminator (manufactured by LINTEC Co., Ltd., product name "RAD-3510F/12" ), attach the adhesive sheet to the wafer. In addition, at the time of sticking, the laminating table and laminating roller of the laminator described above were set at 60°C.

After lamination, using a UV irradiation device (manufactured by LINTEC Co., Ltd., product name "RAD-2000m/12"), under the conditions of illuminance 220mW/cm ² , light intensity 560mJ/cm ² , and irradiation speed 15mm/sec, self-adhesion is thin The side of the sheet is irradiated with ultraviolet rays.

Next, in an environment of 50°C and 50% relative humidity, using a tensile testing machine (manufactured by Shimadzu Corporation, product name "AUTOGRAPH AG-IS 1KN"), the wafer is transferred from the wafer at a tensile speed of 120mm/min. Peel off the adhesive sheet.

After peeling, observe the bump-forming surface of the exposed wafer with a digital microscope (manufactured by KYENCE Co., Ltd., product name "VHX-1000") to confirm whether there is any paste remaining. In addition, a scanning electron microscope (manufactured by KYENCE Co., Ltd., product name "VE-9800") was used to observe the bumps of the wafer to confirm whether there was any paste remaining. In addition, compared to a digital microscope, a scanning electron microscope can observe finer paste residues.

The paste residue was evaluated based on the following evaluation criteria.

A: No paste residue was observed in any microscope.

B: No paste residue was observed with a digital microscope, but a slight paste residue was observed with a scanning electron microscope.

C: Paste residue is observed in any microscope.

Next, the substrate with the intermediate layer and the adhesive sheet were produced in the following order. In addition, each part by mass in the following description is expressed in solid content conversion for those diluted with a diluent such as an organic solvent.

[Production of substrate with intermediate layer]

Blending 40 parts by mass of monofunctional urethane acrylate, 45 parts by mass of isobornyl acrylate (IBXA), 15 parts by mass of 2-hydroxypropyl acrylate (HPA), pentaerythritol tetrakis (3-mercaptobutyrate) (Showa Electric Co., Ltd., product name "CALENDS MT PE1", 2-level 4-functional thiol-containing compound, solid content of 100% by mass) 3.5 parts by mass, 1.8 parts by mass of crosslinking agent, and 2-parts as a photopolymerization initiator 1.0 part by mass of hydroxy-2-methyl-1-phenyl-propan-1-one (manufactured by BASF Corporation, product name "DAROCURE 1173", solid content concentration 100% by mass), to prepare a resin composition for the intermediate layer. The resin composition for the intermediate layer was coated on a PET-based release film (manufactured by LINTEC Co., Ltd., product name "SP-PET381031", thickness 38 μm) by a fountain die nozzle method to form a coating film.

Next, ultraviolet rays are irradiated from the coating film side to form a semi-cured layer. In addition, the ultraviolet radiation system uses a belt conveyor type ultraviolet radiation device (manufactured by EYE GRAPHICS Co., Ltd., product name "ECS-401GGX") as the ultraviolet radiation device, and a high-pressure mercury lamp (manufactured by EYE GRAPHICS Co., Ltd. product name "K04-L41") ") As an ultraviolet source, the irradiation conditions were performed under the conditions of an illuminance of 112 mW/cm ² with a light wavelength of 365 nm and a light quantity of 177 mJ/cm ² (manufactured by EYE GRAPHICS Co., Ltd., product name "UVPF-A1").

On the semi-hardened layer formed, laminate a substrate made of PET film (manufactured by Toyobo Co., Ltd., product name "COSOMO SHINE A4100", thickness 50μm), and irradiate ultraviolet rays from the PET film side (using the above The ultraviolet irradiation device and ultraviolet source are used as the irradiation conditions: illuminance 271mW/cm ² , light intensity 1,200mJ/cm ² ), completely hardened, and a 300μm thick intermediate layer is formed on the PET film of the base material. A substrate with an intermediate layer was obtained.

[Example 1]

An acrylic polymer (weight average molecular weight: 600,000) obtained by copolymerizing 97 parts by mass of n-butyl acrylate (BA) and 3 parts by mass of acrylic acid (AA) was prepared as the polymer (A).

And for the acrylic copolymer (B') copolymerized by 70 parts by mass of n-butyl acrylate (BA) and 30 parts by mass of 2-hydroxyethyl acrylate (2HEA), for the hydroxyl group derived from 2HEA (100 equivalent) The acrylic polymer (weight average molecular weight: 50,000) obtained by adding 2-isocyanatoethyl methacrylate (manufactured by Showa Denko Co., Ltd., product name "CALENDS MOI") with an addition rate of 90 equivalents was used as the polymer ( B).

In a mixture of 100 parts by mass of polymer (A) and 50 parts by mass of polymer (B), 2,2-dimethoxy-1,2-diphenylethyl as a photopolymerization initiator (E) was added Alkane-1-one (manufactured by BASF, product name "Irgacure651") 14.9 parts by mass, trimethylolpropane-added toluene diisocyanate (manufactured by TOSOH Co., Ltd., product name "CORONATE L" as crosslinking agent (D) ") 4.2 parts by mass, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "TETRAD- C") 0.19 parts by mass, diluted with an organic solvent (methyl ethyl ketone) to a solid content concentration of 20% by mass, and stirred for 30 minutes to prepare a diluted solution of the adhesive composition.

Next, the diluted solution of the prepared adhesive composition was coated on a PET-based release film (manufactured by LINTEC Co., Ltd., product name "SP-PET381031", thickness 38μm), heated at 100°C for 2 minutes to dry, and then peeled off An adhesive layer with a thickness of 10 μm is formed on the film.

Remove the previously produced release film on the substrate with the intermediate layer, and stick the exposed intermediate layer to the adhesive layer on the release film, then cut and remove the unnecessary parts of the widthwise end to obtain the substrate/intermediate layer/adhesive Adhesive sheet formed by the agent layer/peeling sheet. The obtained adhesive sheet and the adhesive layer used in the adhesive sheet were evaluated for fracture stress, fracture elongation, fracture energy, adhesive force, and paste residue in accordance with the above-mentioned evaluation method. The results are shown in Table 1.

A cyclic tensile test was performed on the adhesive layer after curing by the energy ray used in Example 1. The complex stress-strain curve obtained from the cyclic tensile test is shown in Figure 1. The elongation increase in this test is 50%, the elongation (%) is 50% in the first time, 100% in the second time, 150% in the third time, 200% in the fourth time, and 250% in the fifth time. %.

As shown in Figure 1, in the cyclic tensile test, the sample broke at 233% elongation at the fifth elongation, and the stress at this time was 3.26 MPa.

In addition, the maximum value (DSmax) of the stress difference between the curves under the same elongation read from FIG. 1 is 1.55 MPa. DSmax is 48% relative to the stress at break in the cyclic tensile test.

Similarly, for the adhesive layer before the energy ray hardening used in Example 1, a cyclic tensile test was performed, and the complex stress-strain curve obtained from the test is shown in FIG. 2. The elongation increase in this test is 100%, and the elongation (%) is set to 100% for the first time, 200% for the second time, 300% for the third time, and 400% for the fourth time.

As shown in Figure 2, before the energy ray hardens, the sample breaks at an elongation of 321%, and the stress at this time is 1.41 MPa.

In addition, the maximum value (DSmax) of the stress difference between the curves under the same elongation read from FIG. 2 is 0.20 MPa. DSmax is 14% relative to the stress at break in the cyclic tensile test.

[Example 2]

Except for 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "TETRAD-C") as the crosslinking agent (C) Except for changing the usage amount to 0.38 parts by mass, an adhesive sheet was produced in the same procedure as in Example 1.

[Example 3]

Except for 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "TETRAD-C") as the crosslinking agent (C) Except for changing the usage amount to 0.57 parts by mass, an adhesive sheet was produced in the same procedure as in Example 1.

[Comparative Example 1]

For the acrylic copolymer copolymerized by 90 parts by mass of 2-hydroxyethyl acrylate (2EHA) and 10 parts by mass of 4-hydroxybutyl acrylate (4HBA), the addition rate to the hydroxyl group (100 equivalent) from 4HBA is 2-isocyanatoethyl methacrylate (manufactured by Showa Denko Co., Ltd., product name "CALENDS MOI") was added with 65 equivalents to obtain an acrylic polymer (weight average molecular weight: 1,000,000). To 100 parts by mass of the acrylic polymer, 3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF Corporation, product name "Irgacure 184") as a photopolymerization initiator was added, and trimethylol as a crosslinking agent 1.1 parts by mass of toluene diisocyanate (manufactured by TOSOH Co., Ltd., product name "CORONATE L") added with methyl propane, diluted with an organic solvent (methyl ethyl ketone) to a concentration of 20% by mass, stirred for 30 minutes to prepare an adhesive The diluent of the composition. Next, the diluted solution of the prepared adhesive composition was applied to a PET-based release film (manufactured by LINTEC Co., Ltd., product name "SP-PET381031", thickness 38μm), heated at 100°C for 2 minutes to dry, and then peeled off. An adhesive layer with a thickness of 10 μm is formed on the film.

Remove the release film on the substrate with the intermediate layer made previously, and after the exposed intermediate layer is bonded to the adhesive layer, cut and remove the unnecessary parts at the end in the width direction to obtain the substrate/intermediate layer/adhesive layer/release Adhesive flakes made of flakes. The obtained adhesive sheet and the adhesive layer used in the adhesive sheet were evaluated according to the above-mentioned evaluation method. The results are shown in Table 1.

In addition, a cyclic tensile test was performed on the adhesive layer after the energy ray used in Comparative Example 1 was cured. The complex stress-strain curve obtained from the cyclic tensile test is shown in Figure 3. The elongation increase in this test is 5%, and the elongation setting (%) is 5% for the first time, 10% for the second time, 15% for the third time, and 20% for the fourth time.

As shown in Figure 3, in the cyclic tensile test, the sample broke at 20% elongation at the fourth elongation, and the stress at this time was 0.94 MPa.

Also, as shown in Fig. 3, the stress-strain curves during the first to fourth stretches all overlap. Therefore, the maximum value (DSmax) of the stress difference between the curves under the same elongation read from the stress-strain curve is 0 MPa, which is 0% relative to the stress at break in the cyclic tensile test.

The adhesive composition of Examples 1 to 3 contains a polymer (A) and a polymer (B), and a cross-linking agent (C) and a cross-linking agent (D) cross-linked respectively, and the polymer (B) It has energy ray polymerizable group (B2), so it forms a proper double network after energy ray irradiation. Therefore, as is clear from Figure 1, the adhesive layer shows specific hysteresis and good breaking strength. When peeling the adhesive sheet from the workpiece (that is, the bump forming surface of the wafer), it can effectively prevent the paste residue on the surface of the workpiece. . In addition, the adhesion values before and after the energy ray irradiation are both appropriate. Furthermore, as is apparent from FIG. 2, the adhesive composition of the embodiment showed insufficient hysteresis before the energy ray irradiation, and did not properly form a double network.

In contrast, in Comparative Example 1, since only one type of polymer and a crosslinking agent for crosslinking the polymer were blended, the fracture characteristics were not good, and the residue of the paste could not be appropriately prevented.

Claims (11)

An adhesive sheet for semiconductor processing, which is an adhesive sheet for semiconductor processing provided with a substrate, and an adhesive layer formed on one side of the substrate and formed by an adhesive composition, characterized by the aforementioned adhesive The agent composition contains a polymer (A) with a reactive functional group (A1), a polymer with a reactive functional group (B1) and an energy ray polymerizable group (B2) different from the reactive functional group (A1) (B), the crosslinking agent (C) that reacts with the reactive functional group (A1), and the crosslinking agent (D) that reacts with the reactive functional group (B1), the aforementioned crosslinking agent (C) and the aforementioned crosslinking The agents (D) are of different kinds. The adhesive sheet for semiconductor processing according to claim 1, wherein the weight average molecular weight of the polymer (A) is higher than the weight average molecular weight of the polymer (B). Such as the adhesive sheet for semiconductor processing of claim 2, wherein the polymer (A) and the polymer (B) are both acrylic polymers. The adhesive sheet for semiconductor processing according to claim 3, wherein the weight average molecular weight of the acrylic polymer constituting the polymer (A) is higher than the weight average molecular weight of the acrylic polymer constituting the polymer (B) by a difference of 200,000 or more. Such as the adhesive sheet for semiconductor processing of claim 4, which constitutes a poly The weight average molecular weight of the acrylic polymer of the compound (A) is 300,000 to 1,000,000, and the weight average molecular weight of the acrylic polymer constituting the polymer (B) is 5,000 to 100,000. The adhesive sheet for semiconductor processing according to any one of claims 3 to 5, wherein the acrylic polymer constituting the polymer (A) is a composition containing a functional monomer (a1) derived from a reactive functional group (A1) The unit, and the acrylic copolymer (A') of the structural unit derived from the alkyl (meth)acrylate (a2). The adhesive sheet for semiconductor processing according to any one of claims 3 to 5, wherein the acrylic polymer constituting the polymer (B) is an energy ray polymerizable group-containing compound (B2) having an energy ray polymerizable group (B2) S) and acrylic copolymer (B') containing a structural unit derived from a functional monomer (b1) having a reactive functional group (B1) and a structural unit derived from an alkyl (meth)acrylate (b2) Part of the reactive functional group (B1) is the reactant obtained by the reaction. The adhesive sheet for semiconductor processing according to any one of claims 1 to 5, wherein the reactive functional group (A1) is a carboxyl group, and the reactive functional group (B1) is a hydroxyl group. The adhesive sheet for semiconductor processing according to claim 8, wherein the crosslinking agent (C) is an epoxy-based crosslinking agent, and the crosslinking agent (D) is an isocyanate-based crosslinking agent. Such as the adhesive sheet for semiconductor processing in any one of Claims 1 to 5, wherein the content of the crosslinking agent (D) is more than the content of the crosslinking agent (C) on a mass basis. The adhesive sheet for semiconductor processing according to claim 10, wherein in the adhesive composition, the content of the crosslinking agent (D) is greater than the content of the crosslinking agent (C) on a mass basis, and is relative to the polymer ( B) For 100 parts by mass, the content of the crosslinking agent (D) of the adhesive composition is 2-20 parts by mass.

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