CN113061401A

CN113061401A - Adhesive sheet for semiconductor processing

Info

Publication number: CN113061401A
Application number: CN202011461200.9A
Authority: CN
Inventors: 河野广希; 小坂尚史; 龟井胜利
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2019-12-13
Filing date: 2020-12-11
Publication date: 2021-07-02
Also published as: TW202136455A; KR20210075873A; JP2021097074A

Abstract

The invention provides an adhesive sheet for semiconductor processing, which is also suitable for a use mode including a high-temperature process. The invention provides an adhesive sheet for semiconductor processing, which comprises an adhesive layer constituting an adhesive surface. In one embodiment, the adhesive sheet for semiconductor processing has an initial normal peeling force Fd₀0.10N/20mm or more, and a normal peeling force Fd after a heat treatment at 150 ℃ for 15 minutes_aIs 1.00N/20mm or less.

Description

Adhesive sheet for semiconductor processing

Technical Field

The present invention relates to an adhesive sheet for semiconductor processing.

Background

In the process of manufacturing a semiconductor device, a step of grinding, dicing, or the like a semiconductor wafer having a circuit formed thereon is generally performed in a state where an adhesive sheet (adhesive sheet for semiconductor processing) is attached to the circuit forming surface side of the semiconductor wafer (adherend) in order to protect and fix the semiconductor wafer. For example, in grinding (back grinding) the back surface of a semiconductor wafer, a back grinding tape is used to protect the circuit formation surface (front surface) of the semiconductor wafer and to hold (fix) the semiconductor wafer (for example, patent document 1).

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-212441

Disclosure of Invention

Problems to be solved by the invention

Background arta back-grinding tape and other adhesive sheets for semiconductor processing are peeled from an adherend at a desired timing after the purpose of use is achieved. Therefore, the pressure-sensitive adhesive sheet for semiconductor processing is required to have good balance between adhesion to an adherend during processing, bonding reliability, and peelability when peeled from the adherend. However, even in the case of a pressure-sensitive adhesive sheet for semiconductor processing which achieves the above characteristics in a well-balanced manner in a room temperature range, when the pressure-sensitive adhesive sheet is exposed to a high temperature state of a predetermined temperature or higher after being attached to an adherend, the peeling force is greatly increased, and thus adhesive residue on the adherend and damage to the adherend due to a load at the time of peeling may occur. In particular, in recent years, with the miniaturization, thinning, and high integration of semiconductor devices, there is a tendency for semiconductor wafers after back grinding to be thinner, and there is a demand for an adhesive sheet for semiconductor processing that can be peeled off while suppressing the load on an adherend even after being subjected to a processing process (high-temperature process) at high temperature.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an adhesive sheet for semiconductor processing that is also suitable for use in a manner including a high-temperature process.

Means for solving the problems

The adhesive sheet for semiconductor processing disclosed in the present specification includes an adhesive layer constituting an adhesive surface. In some embodiments of the above adhesive sheet for semiconductor processing (hereinafter, sometimes abbreviated as "adhesive sheet"), the adhesive sheet has an initial normal peeling force Fd₀0.10N/20mm or more (hereinafter, also referred to as "condition A") and a normal peeling force Fd after a heat treatment at 150 ℃ for 15 minutes_aIs 1.00N/20mm or less(hereinafter, also referred to as "condition B"). For limiting the initial conventional peel force Fd as described above₀Lower limit of (2) and a normal peeling force Fd after a heat treatment at 150 ℃ for 15 minutes_aThe pressure-sensitive adhesive sheet having the upper limit of (hereinafter also referred to as "conventional peeling force after heating at 150 ℃) can achieve adhesion to an adherend and bonding reliability during processing and peelability during peeling from the adherend in a well-balanced manner even in a use mode including a high-temperature process.

In some embodiments of the pressure-sensitive adhesive sheet for semiconductor processing disclosed in the present specification, the pressure-sensitive adhesive sheet satisfies the above condition a, and has a water peeling force Fw measured by supplying water to a peeling front edge of the pressure-sensitive adhesive sheet peeled from an adherend after heat treatment at 150 ℃ for 15 minutes_aIs 0.30N/20mm or less (hereinafter, also referred to as "condition C"). For limiting the initial conventional peel force Fd as described above₀Lower limit of (3) and water peeling force Fw after 15 minutes of heat treatment at 150 DEG C_a(hereinafter, also referred to as "water peeling force after heating at 150 ℃), the pressure-sensitive adhesive sheet having the upper limit can achieve adhesion to an adherend and bonding reliability during processing and peelability during peeling from the adherend, in a well-balanced manner, even in a use mode including a high-temperature process. By performing the above-described peeling from the adherend by the water peeling method, the load on the adherend can be further reduced.

In some embodiments of the adhesive sheet for semiconductor processing disclosed in the present specification, the adhesive sheet satisfies the above condition a and has a normal peeling force Fd after a heat treatment at 200 ℃ for 15 minutes_b3.00N/20mm or less (hereinafter, also referred to as "condition D"). For limiting the initial conventional peel force Fd as described above₀Lower limit of (2) and a normal peeling force Fd after a heat treatment at 200 ℃ for 15 minutes_bThe pressure-sensitive adhesive sheet having the upper limit of (hereinafter also referred to as "normal peeling force after heating at 200 ℃) can achieve adhesion to an adherend and bonding reliability during processing and peelability during peeling from the adherend in a well-balanced manner even in a usage mode including a high-temperature process under more severe conditions.

In some embodiments of the pressure-sensitive adhesive sheet for semiconductor processing disclosed in the present specification, the pressure-sensitive adhesive sheet satisfies the above condition a, and has a water peeling force Fw measured by supplying water to a peeling front edge of the pressure-sensitive adhesive sheet peeled from an adherend after heat treatment at 200 ℃ for 15 minutes_bIs 2.00N/20mm or less (hereinafter, also referred to as "condition E"). For limiting the initial conventional peel force Fd as described above₀Lower limit of (3) and water peeling force Fw after heat treatment at 200 ℃ for 15 minutes_b(hereinafter, also referred to as "water peeling force after heating at 200 ℃), the pressure-sensitive adhesive sheet having the upper limit can achieve adhesion to an adherend and bonding reliability during processing and peeling from the adherend in a well-balanced manner even in a use mode including a high-temperature process under more severe conditions. By performing the above-described peeling from the adherend by the water peeling method, the load on the adherend can be further reduced.

In some embodiments of the adhesive sheet for semiconductor processing disclosed in the present specification, the adhesive sheet is subjected to a conventional peeling force Fd after a heat treatment at 150 ℃ for 15 minutes_a[N/20mm]And a normal peeling force Fd after a heat treatment at 200 ℃ for 15 minutes_b[N/20mm]By the following formula: fd_b/Fd_aThe calculated normal peeling force ratio is 4.0 or less. Therefore, the pressure-sensitive adhesive sheet is less susceptible to the influence of the peeling force even if treatment unevenness such as temperature unevenness occurs in a high-temperature process.

In some embodiments of the adhesive sheet for semiconductor processing disclosed in the present specification, the adhesive sheet is subjected to a conventional peeling force Fd after a heat treatment at 150 ℃ for 15 minutes_a[N/20mm]And a normal peeling force Fd after a heat treatment at 200 ℃ for 15 minutes_b[N/20mm]By the following formula: fd_b-Fd_aThe calculated difference in the conventional peeling force was 1.50N/20mm or less. Therefore, the pressure-sensitive adhesive sheet is less susceptible to the influence of the peeling force even if treatment unevenness such as temperature unevenness occurs in a high-temperature process.

The scope of the invention claimed in the present application may include a combination of the above-described elements as appropriate.

Drawings

FIG. 1 is a sectional view schematically showing one configuration example of a pressure-sensitive adhesive sheet.

FIG. 2 is a sectional view schematically showing another example of the structure of the pressure-sensitive adhesive sheet.

FIG. 3 is a sectional view schematically showing another example of the structure of the pressure-sensitive adhesive sheet.

FIG. 4 is a sectional view schematically showing another example of the structure of the pressure-sensitive adhesive sheet.

FIG. 5 is a sectional view schematically showing another example of the structure of the pressure-sensitive adhesive sheet.

FIG. 6 is a sectional view schematically showing another example of the structure of the pressure-sensitive adhesive sheet.

Description of the reference numerals

1.2, 3, 4, 5, 6 adhesive sheet

10 base material

10A first side

10B second side

21. 22 adhesive layer

21A first adhesive surface

21B second adhesive surface

31. 32 Release liner

Detailed Description

Preferred embodiments of the present invention will be described below. It is to be noted that matters necessary for carrying out the present invention other than the matters specifically described in the present specification can be understood by those skilled in the art based on the teaching of carrying out the present invention described in the present specification and the technical common knowledge at the time of application. The present invention can be implemented based on the contents disclosed in the present specification and the common technical knowledge in the field. In the following drawings, members and portions having the same function are sometimes described with the same reference numerals, and repeated description may be omitted or simplified. In addition, the embodiments shown in the drawings are schematically illustrated for the sake of clarity of the present invention, and do not necessarily accurately show the size and the scale of a product actually provided.

In the present specification, a method of peeling a pressure-sensitive adhesive sheet from an adherend using an aqueous peeling liquid such as water (typically, a method of peeling the pressure-sensitive adhesive sheet by supplying an aqueous peeling liquid to a peeling front edge peeled from the adherend) is sometimes referred to as "water peeling" or "water peeling method".

In the present specification, the term "acrylic polymer" refers to a polymer derived from a monomer raw material containing more than 50% by weight (preferably more than 70% by weight, for example, more than 90% by weight) of an acrylic monomer. The acrylic monomer is a monomer having at least 1 (meth) acryloyl group in 1 molecule. In the present specification, the term "(meth) acryloyl group" means an acryloyl group or a methacryloyl group. Similarly, the term "(meth) acrylate" means a meaning including acrylate and methacrylate, and the term "(meth) acryl-" means a meaning including acryl-and methacryl-, respectively.

In the present specification, the term "active energy ray" refers to a concept including light such as ultraviolet rays, visible rays, and infrared rays, radiation such as α rays, β rays, γ rays, electron beams, neutron beams, and X rays, and the like.

< example of construction of adhesive sheet >

The pressure-sensitive adhesive sheet disclosed in the present specification includes a pressure-sensitive adhesive layer. Typically, the adhesive layer constitutes at least one surface of the adhesive sheet. The pressure-sensitive adhesive sheet may be a substrate-attached pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer on one or both surfaces of a substrate (support), or may be a pressure-sensitive adhesive sheet not including a substrate (substrate-free pressure-sensitive adhesive sheet).

The concept of an adhesive sheet as referred to herein may include articles referred to as adhesive tapes, adhesive labels, adhesive films, and the like. The pressure-sensitive adhesive layer may be formed continuously, but is not limited to the above form, and may be formed in a regular or irregular pattern such as dots or stripes, for example. The pressure-sensitive adhesive sheet provided by the present specification may be in the form of a roll or a sheet. Alternatively, the pressure-sensitive adhesive sheet may be further processed into various shapes.

The pressure-sensitive adhesive sheet disclosed in the present specification may be, for example, a pressure-sensitive adhesive sheet having a cross-sectional structure schematically shown in fig. 1 to 6. Fig. 1 and 2 show examples of the structure of a substrate-attached pressure-sensitive adhesive sheet (substrate-attached one-sided pressure-sensitive adhesive sheet) having one-sided adhesiveness. The psa sheet 1 shown in fig. 1 has a structure in which a psa layer 21 is provided on one surface 10A (non-releasable) of a substrate 10, and the surface (psa surface) 21A of the psa layer 21 is protected by a release liner 31 that serves as a release surface on at least the psa layer side. The pressure-sensitive adhesive sheet 2 shown in fig. 2 has a structure in which a pressure-sensitive adhesive layer 21 is provided on one surface 10A (non-releasable) of a substrate 10. The other surface 10B of the substrate 10 of the psa sheet 2 is a release surface, and when the psa sheet 2 is wound, the psa layer 21 comes into contact with the other surface 10B, and the surface (psa surface) 21A of the psa layer is protected by the other surface 10B of the substrate 10.

Fig. 3 and 4 show an example of the structure of a double-sided pressure-sensitive adhesive sheet with a substrate (double-sided pressure-sensitive adhesive sheet with a substrate). The adhesive sheet 3 shown in fig. 3 has the following structure: a pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer) 21 and a pressure-sensitive adhesive layer (second pressure-sensitive adhesive layer) 22 are provided on the first surface 10A and the second surface 10B (both of which are non-releasable) of the substrate 10, respectively, and the surface (first pressure-sensitive adhesive surface) of the first pressure-sensitive adhesive layer 21 and the surface (second pressure-sensitive adhesive surface) of the second pressure-sensitive adhesive layer 22 are protected by

release liners

31 and 32 which are release surfaces on at least the pressure-sensitive adhesive layer side, respectively. The adhesive sheet 4 shown in fig. 4 has the following structure: the first pressure-sensitive adhesive layer 21 and the second pressure-sensitive adhesive layer 22 are provided on the first surface 10A and the second surface 10B (both non-releasable) of the substrate 10, respectively, and the surface (first pressure-sensitive adhesive surface) of the first pressure-sensitive adhesive layer 21 is protected by a release liner 31 having both surfaces serving as release surfaces. The psa sheet 4 is wound around the psa sheet 4 such that the front surface (second adhesive surface) of the second psa layer 22 contacts the back surface of the release liner 31, whereby the second adhesive surface is also protected by the release liner 31.

Fig. 5 and 6 show examples of the structure of a substrate-less double-sided adhesive sheet (substrate-less double-sided adhesive sheet). The psa sheet 5 shown in fig. 5 has a structure in which one surface (first psa surface) 21A and the other surface (second psa surface) 21B of the substrate-less psa layer 21 are protected by

release liners

31 and 32, respectively, which are release surfaces on at least the psa layer side. The psa sheet 6 shown in fig. 6 has a structure in which one surface (first psa surface) 21A of the psa layer 21 is protected by a release liner 31 having release surfaces on both sides, and when it is wound, the other surface (second psa surface) 21B of the psa layer 21 comes into contact with the back surface of the release liner 31, so that the other surface 21B is also protected by the release liner 31.

A substrate-less or substrate-attached double-sided adhesive sheet can be used as a substrate-attached single-sided adhesive sheet by attaching a non-releasable substrate to one adhesive surface.

The pressure-sensitive adhesive sheet before use (before attachment to an adherend) may be, for example, a release liner-equipped pressure-sensitive adhesive sheet having a pressure-sensitive adhesive surface protected by a release liner as shown in fig. 1 to 6. The release liner is not particularly limited, and examples thereof include release liners obtained by subjecting the surface of a liner base material such as a resin film or paper to a release treatment, and release liners formed of a low-adhesion material such as a fluorine-based polymer (polytetrafluoroethylene or the like) or a polyolefin-based resin (polyethylene, polypropylene or the like). For the above-mentioned release treatment, for example, a silicone-based or long-chain alkyl-based release treatment agent can be used. In some modes, it may be preferable to use a resin film subjected to a release treatment as a release liner.

In the case where the pressure-sensitive adhesive sheet disclosed in the present specification is in the form of a double-sided pressure-sensitive adhesive sheet with a substrate or a double-sided pressure-sensitive adhesive sheet without a substrate, the pressure-sensitive adhesive (first pressure-sensitive adhesive) constituting the first pressure-sensitive adhesive surface and the pressure-sensitive adhesive (second pressure-sensitive adhesive) constituting the second pressure-sensitive adhesive surface may have the same composition or different compositions. The substrate-free double-sided pressure-sensitive adhesive sheet having the first pressure-sensitive adhesive surface and the second pressure-sensitive adhesive surface of different compositions can be realized, for example, by a pressure-sensitive adhesive layer having a multilayer structure in which two or more pressure-sensitive adhesive layers having different compositions are directly laminated (without interposing a substrate therebetween).

< adhesive layer >

The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet disclosed in the present specification may be a pressure-sensitive adhesive layer composed of 1 or 2 or more kinds of pressure-sensitive adhesives selected from known various pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives (natural rubber-based, synthetic rubber-based, and mixed systems thereof), polysiloxane pressure-sensitive adhesives, polyester pressure-sensitive adhesives, urethane pressure-sensitive adhesives, polyether pressure-sensitive adhesives, polyamide pressure-sensitive adhesives, and fluorine pressure-sensitive adhesives. Here, the acrylic adhesive refers to an adhesive containing an acrylic polymer as a base polymer. The same applies to other adhesives such as rubber adhesives.

In the present specification, the term "base polymer" of the binder means a main component of a polymer contained in the binder. In the present specification, the term "main component" means a component contained in an amount exceeding 50% by weight unless otherwise specified.

(acrylic adhesive layer)

In some embodiments of the pressure-sensitive adhesive sheet disclosed in the present specification, the pressure-sensitive adhesive layer may be an acrylic pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive as a main component. In the adhesive sheet having an acrylic adhesive layer, the adhesive properties suitable for semiconductor processing and the light peelability by water peeling can be suitably and simultaneously realized.

The acrylic pressure-sensitive adhesive preferably contains, as a base polymer, for example, an acrylic polymer that is a polymer of a monomer raw material containing an alkyl (meth) acrylate. As the constituent component of the monomer raw material, an alkyl (meth) acrylate having a linear or branched alkyl group having 1 to 20 carbon atoms at the ester end can be preferably used. Hereinafter, an alkyl (meth) acrylate having an alkyl group having not less than X and not more than Y carbon atoms at the ester end may be referred to as "(meth) acrylic acid C_X-YAlkyl ester ". (meth) acrylic acid C as an adhesive property suitable for semiconductor processing_1-20Alkyl esters, preferably (meth) acrylic acid C_1-14(e.g. C)_1-12) An alkyl ester. In addition, as acrylic acid C_1-20Alkyl esters, preferably acrylic acid C_1-20(e.g. C)_1-14Typically C_1-12) Alkane (I) and its preparation methodAnd (c) a base ester.

As (meth) acrylic acid C_1-20Non-limiting specific examples of the alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, dodecyl (meth) acrylate, and the like, Pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate, and the like. These alkyl (meth) acrylates may be used singly in 1 kind or in combination in 2 or more kinds. Preferred examples of the alkyl (meth) acrylate include Ethyl Acrylate (EA), n-Butyl Acrylate (BA), 2-ethylhexyl acrylate (2EHA), and Lauryl Acrylate (LA). In some embodiments, the monomer feed preferably comprises at least one of EA, BA, 2EHA, and LA, more preferably at least one of EA, BA, and 2EHA, and even more preferably at least one of BA and 2 EHA.

In view of balance of easy-to-obtain characteristics, some embodiments of the (meth) acrylic acid C_1-20The proportion of the alkyl ester in the monomer raw materials is usually preferably 40% by weight or more, preferably more than 50% by weight, for example, 55% by weight or more, 60% by weight or more, 65% by weight or more, and 70% by weight or more. For the same reason, (meth) acrylic acid C in the monomer raw material_1-20The proportion of the alkyl ester is usually preferably 99.9% by weight or less, may be 99% by weight or less, and may be 98% by weight or less. Aqueous release from easily formed release front suitable for being based on release from adherendIn some embodiments, from the viewpoint of the pressure-sensitive adhesive sheet with light release from the release liquid, (meth) acrylic acid C in the monomer raw material_1-20The proportion of the alkyl ester may be, for example, 95% by weight or less, may be 85% by weight or less, may be less than 80% by weight, may be 70% by weight or less, and may be 65% by weight or less.

The monomer raw material usable for the synthesis of the acrylic polymer may further contain a secondary monomer copolymerizable with the above-mentioned alkyl (meth) acrylate. The auxiliary monomer may contribute to introduction of a crosslinking point into the acrylic polymer or increase the cohesive force of the acrylic polymer.

As the auxiliary monomer, 1 kind of monomer having a functional group such as the following, for example, can be used alone or 2 or more kinds can be used in combination.

Hydroxyl group-containing monomer: hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and (4-hydroxymethylcyclohexyl) methyl (meth) acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol; ether compounds such as 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether and diethylene glycol monovinyl ether.

Carboxyl group-containing monomer: for example, ethylenically unsaturated monocarboxylic acids such as Acrylic Acid (AA), methacrylic acid (MAA), crotonic acid, and isocrotonic acid; ethylenically unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, and citraconic acid.

Acid anhydride group-containing monomer: for example maleic anhydride, itaconic anhydride.

Monomers having a ring containing a nitrogen atom: such as N-vinyl-2-pyrrolidone, methyl-N-vinylpyrrolidone, vinylpyridine, vinylpyrazine, vinylpyrimidine, N-vinylpiperidone, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole, N-vinyloxazole, N-vinylmorpholine, N-vinyl-3-morpholinone, N-vinyl-2-caprolactam, N-vinyl-1, 3-oxazin-2-one, N-vinyl-3, 5-morpholinodione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, N-vinylisothiazole, N- (meth) acryloyl morpholine, N-vinylpyridine, N-vinylpyrazole, N-vinylpyridine, N-vinylpyrimidin, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloyl piperidine, N- (meth) acryloyl pyrrolidine, and the like.

Amide group-containing monomer: for example, (meth) acrylamide; n, N-dialkyl (meth) acrylamides such as N, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-dipropyl (meth) acrylamide, N-diisopropyl (meth) acrylamide, N-di (N-butyl) (meth) acrylamide, and N, N-di (tert-butyl) (meth) acrylamide; n-alkyl (meth) acrylamides such as N-ethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-N-butyl (meth) acrylamide; n-vinylcarboxylic acid amides such as N-vinylacetamide; monomers having a hydroxyl group and an amide group, for example, N-hydroxyalkyl (meth) acrylamides such as N- (2-hydroxyethyl) (meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide, N- (1-hydroxypropyl) (meth) acrylamide, N- (3-hydroxypropyl) (meth) acrylamide, N- (2-hydroxybutyl) (meth) acrylamide, N- (3-hydroxybutyl) (meth) acrylamide, and N- (4-hydroxybutyl) (meth) acrylamide; monomers having an alkoxy group and an amide group, for example, N-alkoxyalkyl (meth) acrylamides such as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide; n, N-dialkylaminoalkyl (meth) acrylamides such as N, N-dimethylaminopropyl (meth) acrylamide, and the like.

Amino group-containing monomers: for example, aminoethyl (meth) acrylate, N-dimethylaminoethyl (meth) acrylate, tert-butylaminoethyl (meth) acrylate.

Monomer having succinimide skeleton: for example, N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyhexamethylene succinimide, and the like.

Maleimide group: for example, N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide and the like.

Itaconimides: for example, N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-lauryl itaconimide, etc.

Epoxy group-containing monomer: such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether.

Cyano group-containing monomers: such as acrylonitrile, methacrylonitrile.

Ketone group-containing monomer: for example diacetone (meth) acrylamide, diacetone (meth) acrylate, vinyl methyl ketone, vinyl ethyl ketone, allyl acetoacetate, vinyl acetoacetate.

Alkoxysilyl group-containing monomer: for example, alkoxysilyl group-containing (meth) acrylates such as 3- (meth) acryloyloxypropyltrimethoxysilane, 3- (meth) acryloyloxypropyltriethoxysilane, 3- (meth) acryloyloxypropylmethyldimethoxysilane and 3- (meth) acryloyloxypropylmethyldiethoxysilane, and alkoxysilyl group-containing vinyl compounds such as vinyltrimethoxysilane and vinyltriethoxysilane.

Monomer having epoxy group: such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether.

Sulfonic acid group-or phosphoric acid group-containing monomer: for example, styrenesulfonic acid, allylsulfonic acid, sodium vinylsulfonate, 2- (meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalenesulfonic acid, 2-hydroxyethyl acryloylphosphate, and the like.

Isocyanate group-containing monomer: such as 2-isocyanatoethyl (meth) acrylate, (meth) acryloyl isocyanate, m-isopropenyl-alpha, alpha-dimethylbenzyl isocyanate.

The amount of the functional group-containing monomer is not particularly limited, and may be appropriately selected so that a desired cohesive force can be achieved. In general, from the viewpoint of achieving both the cohesive force and other properties (e.g., adhesiveness) in a well-balanced manner, the amount of the functional group-containing monomer (the total amount of 2 or more functional group-containing monomers when used) is preferably 0.1% by weight or more, preferably 0.3% by weight or more, for example 1% by weight or more, of the total amount of the monomer raw materials. The amount of the functional group-containing monomer may be, for example, 50 wt% or less, or may be 40 wt% or less, based on the whole monomer raw material. In some embodiments, the amount of the functional group-containing monomer may be 30 wt% or less, 25 wt% or less, 20 wt% or less, 10 wt% or less, or 5 wt% or less of the total monomer raw materials, from the viewpoint of easily suppressing an increase in peeling force due to heating.

In some embodiments, the monomer raw material may include a hydroxyl group-containing monomer as the functional group-containing monomer. The amount of the hydroxyl group-containing monomer used is not particularly limited, and may be, for example, 0.01% by weight or more, 0.1% by weight or more, 0.5% by weight or more, 1% by weight or more, 5% by weight or more, or 10% by weight or more of the whole monomer raw material. In some embodiments, the amount of the hydroxyl group-containing monomer used may be, for example, 50 wt% or less of the total amount of the monomer raw materials, and is usually preferably 40 wt% or less, may be 30 wt% or less, may be 25 wt% or less, and may be 20 wt% or less, from the viewpoint of suppressing water absorption of the binder. In some embodiments, the amount of the hydroxyl group-containing monomer used may be 15% by weight or less, 10% by weight or less, or 5% by weight or less of the total amount of the monomer raw materials. Alternatively, the hydroxyl group-containing monomer may not be used.

In some embodiments, the monomer raw material may include a carboxyl group-containing monomer as the functional group-containing monomer. The proportion of the carboxyl group-containing monomer in the whole monomer raw materials that can be used for the synthesis of the acrylic polymer may be, for example, 15 wt% or less and 10 wt% or less, and is preferably 7 wt% or less, may be 5 wt% or less, and may be 3 wt% or less, from the viewpoint of suppressing water absorption of the pressure-sensitive adhesive layer during semiconductor processing. The monomer raw material may contain substantially no carboxyl group-containing monomer. Here, the fact that the monomer containing a carboxyl group is not substantially contained means that at least the monomer containing a carboxyl group is not intentionally used.

In some embodiments, the monomer raw material may include a monomer having a nitrogen atom as the functional group-containing monomer. By using a monomer having a nitrogen atom, appropriate polarity can be imparted to the binder. This is advantageous for realizing a pressure-sensitive adhesive sheet suitable for light peeling by supplying an aqueous peeling liquid such as water. As a preferable example of the monomer having a nitrogen atom, a monomer having a ring containing a nitrogen atom is exemplified. As the monomer having a ring containing a nitrogen atom, an N-vinyl type compound (such as an N-vinyl cyclic amide) such as N-vinyl-2-pyrrolidone, or an N- (meth) acryloyl type compound such as N- (meth) acryloylmorpholine can be preferably used from the viewpoint of compatibility.

The amount of the monomer having a nitrogen atom (for example, a monomer having a ring containing a nitrogen atom) used is not particularly limited, and may be, for example, 1% by weight or more, 2% by weight or more, 3% by weight or more, 5% by weight or more, and 7% by weight or more of the whole monomer raw material. In some embodiments, the amount of the monomer having a nitrogen atom to be used may be 10% by weight or more, 15% by weight or more, and 20% by weight or more of the entire monomer raw materials, from the viewpoint of obtaining higher effects. In addition, from the viewpoint of balance of easy-to-obtain characteristics, the amount of the monomer having a nitrogen atom to be used is usually preferably 40% by weight or less, for example, 35% by weight or less, 30% by weight or less, and 25% by weight or less of the whole monomer raw material. In some embodiments, the amount of the monomer having a nitrogen atom to be used may be, for example, 20% by weight or less, 15% by weight or less, 10% by weight or less, or 5% by weight or less of the entire monomer raw material. Alternatively, a monomer having a nitrogen atom may not be used.

The monomer raw material that can be used for producing the acrylic polymer may contain a secondary monomer (hereinafter, also referred to as a copolymerizable monomer) other than the functional group-containing monomer for the purpose of improving the cohesive force of the acrylic polymer.

Specific non-limiting examples of the above-mentioned copolymerizable monomer include the following.

Alkoxy group-containing monomers: alkoxyalkyl (meth) acrylates ((alkoxyalkyl (meth) acrylates) such as 2-methoxyethyl (meth) acrylate, 3-methoxypropyl (meth) acrylate, and 2-ethoxyethyl (meth) acrylate; alkoxy (poly) alkylene glycol (meth) acrylates such as methoxy ethylene glycol (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, and methoxy polypropylene glycol (meth) acrylate.

Vinyl esters: for example, vinyl acetate, vinyl propionate, and the like.

Vinyl ethers: for example, vinyl alkyl ethers such as methyl vinyl ether and ethyl vinyl ether.

Aromatic vinyl compound: for example, styrene, alpha-methylstyrene, vinyltoluene, and the like.

Olefins: for example, ethylene, butadiene, isoprene, isobutylene, and the like.

(meth) acrylate having alicyclic hydrocarbon group: for example, alicyclic hydrocarbon group-containing (meth) acrylates such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and adamantyl (meth) acrylate.

Aromatic ring-containing (meth) acrylates: for example, aryl (meth) acrylates such as phenyl (meth) acrylate, aryloxyalkyl (meth) acrylates such as phenoxyethyl (meth) acrylate, and arylalkyl (meth) acrylates such as benzyl (meth) acrylate.

And heterocyclic ring-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate, halogen atom-containing monomers such as vinyl chloride and fluorine atom-containing (meth) acrylates, organosiloxane chain-containing monomers such as polysiloxane (meth) acrylate, and (meth) acrylates obtained from terpene compound derivative alcohols.

Such a copolymerizable monomer may be used alone in 1 kind or in combination of 2 or more kinds. The amount of the other copolymerizable monomer is not particularly limited, and may be appropriately selected depending on the purpose and use, and is preferably 20 wt% or less (e.g., 2 to 20 wt%, typically 3 to 10 wt%) of the total monomer raw materials of the acrylic polymer.

In a preferred embodiment, the total ratio of the alkoxyalkyl (meth) acrylate and the alkoxy polyalkylene glycol (meth) acrylate is preferably limited to less than 20% by weight of the monomer raw material from the viewpoint of suppressing gelation. The total ratio of the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate is more preferably less than 10% by weight, still more preferably less than 3% by weight, and particularly preferably less than 1% by weight, and in one embodiment, the monomer raw material does not substantially contain the alkoxyalkyl (meth) acrylate and the alkoxypolyalkylene glycol (meth) acrylate (the content is 0 to 0.3% by weight).

Likewise, in one embodiment, the monomer raw material may contain the alkoxy group-containing monomer in a proportion of less than 20% by weight, or may not contain the alkoxy group-containing monomer. The amount of the alkoxy group-containing monomer in the monomer raw material is preferably less than 10% by weight, more preferably less than 3% by weight, and still more preferably less than 1% by weight, and in a particularly preferred embodiment, the monomer raw material does not substantially contain the alkoxy group-containing monomer (the content is 0 to 0.3% by weight).

The method for polymerizing the monomer raw material is not particularly limited, and various polymerization methods known as a method for synthesizing an acrylic polymer, such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a suspension polymerization method, can be suitably used. For example, the solution polymerization method can be preferably employed. As a monomer supply method in performing the solution polymerization, a batch charging method, a continuous supply (dropwise) method, a batch supply (dropwise) method, or the like in which all monomer raw materials are supplied at once can be suitably employed. The solvent (polymerization solvent) used in the solution polymerization may be appropriately selected from conventionally known organic solvents. For example, aromatic compounds (typically, aromatic hydrocarbons) selected from toluene and the like; esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane and cyclohexane; halogenated alkanes such as 1, 2-dichloroethane; lower alcohols such as isopropyl alcohol (e.g., monohydric alcohols having 1 to 4 carbon atoms); ethers such as t-butyl methyl ether; ketones such as methyl ethyl ketone; etc., or a mixed solvent of 2 or more. The polymerization temperature may be appropriately selected depending on the kind of the monomer and the solvent used, the kind of the polymerization initiator, and the like, and may be, for example, about 20 ℃ to 120 ℃ (typically about 40 ℃ to 80 ℃). The solution polymerization can provide a polymerization reaction solution in which the polymer of the monomer raw material is dissolved in the polymerization solvent. The adhesive composition for forming the adhesive layer can be preferably produced using the above polymerization reaction liquid.

In the polymerization, a known or customary thermal polymerization initiator or photopolymerization initiator can be used depending on the polymerization method, polymerization system, and the like. Examples of the thermal polymerization initiator include azo polymerization initiators, peroxide initiators, redox initiators based on a combination of a peroxide and a reducing agent, and substituted ethane initiators. Examples of the photopolymerization initiator include an α -ketol photoinitiator, an acetophenone photoinitiator, a benzoin ether photoinitiator, a ketal photoinitiator, an aromatic sulfonyl chloride photoinitiator, a photoactive oxime photoinitiator, a benzophenone photoinitiator, a thioxanthone photoinitiator, and an acylphosphine oxide photoinitiator. The polymerization initiator may be used in 1 kind alone or 2 or more kinds in appropriate combination.

The amount of the polymerization initiator to be used may be a usual amount, and may be selected from a range of about 0.005 to 1 part by weight (typically, 0.01 to 1 part by weight) based on 100 parts by weight of the total monomer raw materials.

In the above polymerization, various conventionally known chain transfer agents (also understood as a molecular weight regulator or a polymerization degree regulator) can be used as necessary. As the chain transfer agent, mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, thioglycolic acid and α -thioglycerol can be used. Alternatively, a chain transfer agent containing no sulfur atom (non-sulfur chain transfer agent) may be used. Specific examples of the non-sulfur chain transfer agent include anilines such as N, N-dimethylaniline and N, N-diethylaniline; terpenoids (terpenoids) such as α -pinene and terpinolene (terpinolene); styrenes such as α -methylstyrene and α -methylstyrene dimer; compounds having benzylidene group such as dibenzylidene acetone, cinnamyl alcohol and cinnamyl aldehyde; hydroquinones such as hydroquinone and naphthalenediol; quinones such as benzoquinone and naphthoquinone; olefins such as 2, 3-dimethyl-2-butene and 1, 5-cyclooctadiene; alcohols such as phenol, benzyl alcohol, and allyl alcohol; benzyl hydrides such as diphenylbenzene and triphenylbenzene; and so on.

The chain transfer agent may be used alone in 1 kind or in combination of 2 or more kinds. When a chain transfer agent is used, the amount thereof may be, for example, about 0.01 to 1 part by weight per 100 parts by weight of the monomer raw material. The technique disclosed in the present specification can also be preferably carried out by a mode in which no chain transfer agent is used.

The molecular weight of the acrylic polymer is not particularly limited, and may be set in an appropriate range according to the required performance. The weight average molecular weight (Mw) of the acrylic polymer is usually about 10X 10⁴Above (e.g., 20 × 10)⁴As described above), from the viewpoint of achieving both the cohesive force and the adhesive force with good balance, it is preferably more than 30 × 10⁴Preferably about 40X 10⁴Above, it may be about 50X 10⁴Above, it may be about 55X 10⁴The above. The upper limit of the Mw of the acrylic polymer is not particularly limited. From the viewpoint of coatability of the adhesive composition, the Mw of the acrylic polymer is preferably about 500X 10 in general⁴Hereinafter, for example, the thickness may be about 150 × 10⁴Hereinafter, it may be about 75X 10⁴The following. The Mw may be the Mw of the acrylic polymer in the adhesive composition or in the adhesive layer.

Here, Mw means a value obtained by Gel Permeation Chromatography (GPC) in terms of standard polystyrene. As the GPC apparatus, for example, the machine model "HLC-8320 GPC" (column: TSKgelGMH-H (S), manufactured by Tosoh Corporation) can be used. The same applies to the later-described embodiments.

The acrylic pressure-sensitive adhesive layer may further contain a polymer other than the acrylic polymer as a secondary polymer as necessary. The secondary polymer is preferably a polymer other than an acrylic polymer among various polymers exemplified as the polymers that can be contained in the pressure-sensitive adhesive layer. When the pressure-sensitive adhesive layer disclosed in the present specification is an acrylic pressure-sensitive adhesive layer containing not only an acrylic polymer but also a secondary polymer, the content of the secondary polymer is preferably less than 100 parts by weight, more preferably 50 parts by weight or less, even more preferably 30 parts by weight or less, and still more preferably 10 parts by weight or less, relative to 100 parts by weight of the acrylic polymer. The content of the secondary polymer may be 5 parts by weight or less and may be 1 part by weight or less with respect to 100 parts by weight of the acrylic polymer. The technique disclosed in the present specification can be preferably implemented, for example, by an embodiment in which 99.5 to 100% by weight of the polymer contained in the adhesive layer is an acrylic polymer.

(pressure-sensitive adhesive layer other than acrylic)

The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive surface in the pressure-sensitive adhesive sheet disclosed in the present specification may be a pressure-sensitive adhesive layer containing a polymer other than an acrylic polymer as a base polymer, that is, a pressure-sensitive adhesive layer other than an acrylic polymer. The pressure-sensitive adhesive layer other than an acrylic pressure-sensitive adhesive layer may further contain a secondary polymer other than the base polymer, if necessary, in addition to the base polymer. In this case, the content of the secondary polymer in the pressure-sensitive adhesive layer other than the acrylic pressure-sensitive adhesive layer may be selected from the above-mentioned contents exemplified as the content of the secondary polymer in the acrylic pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer other than acrylic may be a pressure-sensitive adhesive layer containing an acrylic polymer as a secondary polymer.

(glass transition temperature)

The glass transition temperature (Tg) of the base polymer (for example, acrylic polymer) constituting the adhesive layer of the adhesive surface is preferably about 15 ℃ or lower. In some embodiments, the Tg is suitably 10 ℃ or less, preferably 0 ℃ or less, may be-10 ℃ or less or-20 ℃ or less, may be-30 ℃ or less, and may be-40 ℃ or less, from the viewpoint of adhesion to an adherend (e.g., conformability to the surface shape of the adherend). From the viewpoint of the cohesive property of the adhesive and the ease of light peeling by water peeling, the Tg of the base polymer may be, for example, -75 ℃ or higher, may be, -60 ℃ or higher, and may be-55 ℃ or higher.

Herein, the glass transition temperature (Tg) of a polymer in the present specification means a glass transition temperature obtained by the Fox equation based on the composition of a monomer raw material constituting the polymer. The Fox formula is a relational expression between Tg of the copolymer and the glass transition temperature Tgi of a homopolymer obtained by homopolymerizing the monomers constituting the copolymer, as shown below.

1/Tg＝Σ(Wi/Tgi)

In the above Fox formula, Tg represents the glass transition temperature (unit: K) of the copolymer, Wi represents the weight fraction of the monomer i in the copolymer (copolymerization ratio on a weight basis), and Tgi represents the glass transition temperature (unit: K) of the homopolymer of the monomer i.

As the glass transition temperature of the homopolymer used for calculation of Tg, the value described in the known data was used. For example, the following monomers are used as the glass transition temperature of the homopolymer of the monomer.

As the glass transition temperature of a homopolymer of a monomer other than those exemplified above, the values described in "Polymer Handbook" (3 rd edition, John Wiley & Sons, Inc.,1989) were used. When a plurality of values are described in this document, the highest value is used.

As for the monomer having no description of the glass transition temperature of the homopolymer in the above-mentioned Polymer Handbook, the value obtained by the following measurement method is used (see Japanese patent laid-open No. 2007-51271). Specifically, 100 parts by weight of a monomer, 0.2 parts by weight of azobisisobutyronitrile and 200 parts by weight of ethyl acetate as a polymerization solvent were put into a reactor equipped with a thermometer, a stirrer, a nitrogen introduction tube and a reflux condenser, and stirred for 1 hour while flowing nitrogen. After the oxygen in the polymerization system was removed as described above, the temperature was raised to 63 ℃ to carry out the reaction for 10 hours. Subsequently, the mixture was cooled to room temperature to obtain a homopolymer solution having a solid content of 33 wt%. Then, the homopolymer solution was cast on a release liner, and dried to prepare a test sample (sheet-like homopolymer) having a thickness of about 2 mm. The test sample was punched out into a disk shape having a diameter of 7.9mm, and the disk shape was sandwiched between parallel plates, and viscoelasticity was measured by a shear mode under conditions of a temperature range of-70 to 150 ℃ and a temperature rise rate of 5 ℃/min while applying a shear strain having a frequency of 1Hz using a viscoelasticity tester (ARES, manufactured by Rheometrics inc.).

(Compound A)

If necessary, a heat-resistant release agent may be contained in the pressure-sensitive adhesive layer. As the heat-resistant peeling agent, at least 1 compound a selected from the group consisting of a surfactant and a compound having a polyoxyalkylene skeleton can be used. The pressure-sensitive adhesive layer containing the heat-resistant release agent exhibits an effect of suppressing an increase in the peel strength of the pressure-sensitive adhesive sheet due to exposure to high temperatures. For example, by containing a heat-resistant release agent in the adhesive layer, the normal release force Fd can be made_a、Fd_bAnd water peeling force Fw_a、Fw_bAt least one of them decreases. The reason for obtaining such an effect is not particularly limited, but can be considered as follows: in general, although there is a possibility that the peeling force may increase as the adhesion between the adherend and the pressure-sensitive adhesive layer progresses by the high-temperature exposure, the increase in peeling force can be suppressed by the presence of the heat-resistant peeling agent on the surface of the pressure-sensitive adhesive layer, and both the surfactant and the compound having a polyoxyalkylene skeleton, which are usable as the heat-resistant peeling agent, haveSince the hydrophilic region is present, the hydrophilic region is likely to be appropriately biased to be present on the surface of the pressure-sensitive adhesive layer, and thus the increase in the peeling force can be effectively suppressed. The heat-resistant release agent has hydrophilic regions as described above, and is likely to be present on the surface of the pressure-sensitive adhesive layer in a moderately biased manner, and thus can also function as a water release additive that contributes to light release by water release.

As the surfactant and the compound having a polyoxyalkylene skeleton, 1 or 2 or more of known surfactants and compounds having a polyoxyalkylene skeleton can be used without particular limitation. Compound a is typically preferably contained in the adhesive layer in a free form. It is to be noted that, in the above-mentioned surfactants, compounds having a polyoxyalkylene skeleton are present, and vice versa.

As the surfactant that can be used as compound a, known nonionic surfactants, anionic surfactants, cationic surfactants, and the like can be used. Among them, nonionic surfactants are preferable. The surfactant may be used alone in 1 kind or in combination of 2 or more kinds.

Examples of the nonionic surfactant include polyoxyethylene alkyl ethers such as polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether; polyoxyethylene alkylphenyl ethers such as polyoxyethylene octylphenyl ether and polyoxyethylene nonylphenyl ether; polyoxyethylene fatty acid esters such as polyoxyethylene monolaurate, polyoxyethylene monostearate, and polyoxyethylene monooleate; sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan monooleate; polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan tristearate, polyoxyethylene sorbitan triisostearate, polyoxyethylene sorbitan monooleate, and polyoxyethylene sorbitan trioleate; polyoxyethylene glyceryl ether fatty acid esters; polyoxyethylene-polyoxypropylene block copolymers; and so on. The nonionic surfactant may be a reactive surfactant having a radical polymerizable functional group such as an acryl group, a (meth) allyl group, a vinyl group, or a (meth) acryl group (for example, a nonionic reactive surfactant such as polyoxyethylene nonylphenyl ether). These nonionic surfactants may be used alone in 1 kind or in combination of 2 or more kinds. From the viewpoint of suitably exhibiting the effect of the compound a being appropriately biased to exist on the surface of the pressure-sensitive adhesive layer and improving the performance stability of the pressure-sensitive adhesive sheet, a (non-reactive) nonionic surfactant having no radical polymerizable functional group as described above can be preferably used.

Examples of the anionic surfactant include alkylbenzenesulfonates such as nonylbenzenesulfonate and dodecylbenzenesulfonate (e.g., sodium dodecylbenzenesulfonate); alkyl sulfates such as lauryl sulfate (e.g., sodium lauryl sulfate, ammonium lauryl sulfate) and stearyl sulfate; a fatty acid salt; polyoxyethylene alkyl ether sulfates such as polyoxyethylene octadecyl ether sulfate and polyoxyethylene lauryl ether sulfate (e.g., sodium polyoxyethylene alkyl ether sulfate), polyoxyethylene alkyl phenyl ether sulfates such as polyoxyethylene lauryl phenyl ether sulfate (e.g., ammonium polyoxyethylene alkyl phenyl ether sulfate and sodium polyoxyethylene alkyl phenyl ether sulfate), and polyether sulfates such as polyoxyethylene styrenated phenyl ether sulfate; polyoxyethylene alkyl ether phosphate esters such as polyoxyethylene stearyl ether phosphate and polyoxyethylene lauryl ether phosphate; polyoxyethylene alkyl ether phosphate ester salts such as sodium salts and potassium salts of the above polyoxyethylene alkyl ether phosphate esters; sulfosuccinates such as lauryl sulfosuccinate and polyoxyethylene lauryl sulfosuccinate (e.g., sodium polyoxyethylene alkyl sulfosuccinate); polyoxyethylene alkyl ether acetate; and so on. When the anionic surfactant forms a salt, the salt may be, for example, a metal salt (preferably a salt of a monovalent metal) such as a sodium salt, a potassium salt, a calcium salt, or a magnesium salt, an ammonium salt, or an amine salt. The anionic surfactants may be used alone in 1 kind or in combination of 2 or more kinds. From the same viewpoint as the nonionic surfactant, a non-reactive anionic surfactant can be preferably used.

Examples of the cationic surfactant include polyether amines such as polyoxyethylene lauryl amine and polyoxyethylene stearyl amine. The cationic surfactant may be used alone in 1 kind or in combination of 2 or more kinds.

As the compound having a polyoxyalkylene skeleton which can be used as compound a, for example, polyalkylene glycols such as polyethylene glycol (PEG) and polypropylene glycol (PPG); polyethers containing polyoxyethylene units, polyethers containing polyoxypropylene units, compounds containing oxyethylene and oxypropylene units (the arrangement of these units may be random or block-like); derivatives thereof; and so on. Further, among the above nonionic, anionic and cationic surfactants, a compound having a polyoxyalkylene skeleton can be used. These can be used alone in 1 or a combination of 2 or more. Among them, a compound containing a polyoxyethylene skeleton (also referred to as a polyoxyethylene segment) is preferably used, and PEG is more preferred.

The molecular weight (formula weight) of the compound having a polyoxyalkylene skeleton (e.g., polyethylene glycol) is not particularly limited. From the viewpoint of uniform mixing, it is, for example, preferably less than 1000, and preferably about 600 or less (for example, 500 or less). The lower limit of the molecular weight of the compound having a polyoxyalkylene skeleton (for example, polyethylene glycol) is not particularly limited, and a compound having a molecular weight of about 100 or more (for example, about 200 or more, further about 300 or more) can be preferably used.

The adhesive layer containing the compound a may be typically formed of an adhesive composition containing the compound a. The adhesive composition containing the compound a may be preferably prepared by a method including a step of adding the compound a in a form of no solvent or adding the compound a in a form of an organic solvent solution. The above-mentioned solvent-free form means a form which is not diluted with an organic solvent or water in which the pressure-sensitive adhesive layer is not formed, and may be formed from, for example, the compound a. The organic solvent used for the preparation of the organic solvent solution can be appropriately selected from conventionally known organic solvents. Specific examples of the organic solvent include the same solvents as those used in the solution polymerization described later. Preferable examples thereof include ethyl acetate, a mixed solvent containing ethyl acetate (which may be a mixed solvent of ethyl acetate and toluene), toluene, and a mixed solvent containing toluene. For example, ethyl acetate or a mixed solvent containing ethyl acetate as a main component can be preferably used. In some embodiments, it is preferable to add the compound a in the form of an organic solvent solution substantially free of water (for example, the content of water is less than 10 parts by weight, less than 5 parts by weight, or less than 1 part by weight relative to 100 parts by weight of the compound a) from the viewpoint of preventing water from being taken into the adhesive composition. This makes it possible to form an adhesive layer with higher uniformity.

In some embodiments, a nonionic compound is preferably used as the compound a in view of ease of incorporation into the adhesive composition with good uniformity. By using the pressure-sensitive adhesive composition containing the compound a with good uniformity, a pressure-sensitive adhesive layer containing the compound a with good uniformity on the surface tends to be formed. This is preferable from the viewpoint of more smoothly peeling the pressure-sensitive adhesive sheet from the adherend and reducing the load applied to the adherend by the fluctuation of the peeling force (for example, vibration or impact accompanying the fluctuation).

The HLB of compound a is not particularly limited. The HLB of compound a may be, for example, 1 or more or 3 or more. The HLB of compound a is preferably 5 or more, may be 6 or more, may be 8 or more, and may be 9 or more. This tends to exhibit water-release properties appropriately. The HLB of compound a is more preferably 10 or more, further preferably 11 or more, further preferably 12 or more, and particularly preferably 13 or more, and may be 14 or more, may be 15 or more, and further may be 16 or more. By the compound a having the HLB in the above range, light peelability by water peeling can be more effectively exhibited. The upper limit of the HLB is 20 or less, and for example, may be 18 or less. In some embodiments, the HLB of compound a may be 16 or less, for example, 15 or less, for example, from the viewpoint of compatibility.

In the present specification, HLB is a hydrophilic-lipophilic Balance (Hydrophile-Lipophile Balance) proposed by Griffin, and is a value representing the degree of affinity of a surfactant with water and oil, and a value between 0 and 20 represents a ratio of hydrophilicity to lipophilicity. HLB is defined as w.c. griffin: J.Soc. cosmetic Chemists, 1,311(1949), Kongqiao Yumin, Nippon Yao Yilang, Xiaochi Zisheng, Xiaolin Zhengxiong, and "surfactant Manual", 3 rd edition, published by Ergonomic book corporation, 11/25/1972, and described in p179 to 182. The compound A having the above HLB can be selected as needed based on the common technical knowledge of those skilled in the art by referring to the above-mentioned references and the like.

In some embodiments, the compound a is preferably a compound having 2 or more hydroxyl groups in one molecule, and more preferably a compound having 3 or more hydroxyl groups in one molecule, from the viewpoint of affinity with the aqueous stripping solution. Examples of the compound a having 2 or 3 or more hydroxyl groups in one molecule include sorbitan monoesters, polyoxyalkylene glyceryl ethers, polyoxyalkylene diglyceryl ethers, and polyoxyalkylene glyceryl ether monoesters. The upper limit of the number of hydroxyl groups in one molecule of the compound a is not particularly limited, and is usually suitably 10 or less, preferably 8 or less, may be 6 or less, and may be 4 or less from the viewpoints of solubility in an organic solvent and easiness of production of the adhesive composition.

In some embodiments, a nonionic compound having a fatty acid ester structure is preferably selected as the compound a from the viewpoint of solubility in an organic solvent (for example, esters such as ethyl acetate). The compound a having a fatty acid ester structure may also become advantageous in terms of compatibility in the adhesive layer. For example, as the compound a contained in the acrylic pressure-sensitive adhesive layer, a compound a having a fatty acid ester structure can be preferably used. Examples of the nonionic compound having a fatty acid ester structure include sorbitan fatty acid esters, polyoxyalkylene fatty acid esters, and polyoxyalkylene fatty acid monoesters.

In some embodiments, the compound a is preferably in a liquid state at room temperature (here, 25 ℃) in a state where the solid content is 100%, from the viewpoint of ease of preparation of an organic solvent solution.

In some embodiments, the compound a is preferably dissolved without phase separation in the following test II, and more preferably dissolved without phase separation in the following test I. The following test I, II was carried out at room temperature (23 to 25 ℃) using compound A as a 100% solid content.

[ test I ]

In a container having a capacity of 200 milliliters (mL), 90g of ethyl acetate and 10g of compound a were placed, stirred with a glass rod for 1 minute, and then allowed to stand for 5 minutes, and then the presence or absence of phase separation was visually observed.

[ test II ]

In a vessel having a capacity of 200mL, 90g of ethyl acetate and 10g of Compound A were placed, stirred with a glass rod for 1 minute, then treated with an ultrasonic dispersion apparatus at 35kHz for 10 minutes, stirred with a glass rod for 1 minute, and then allowed to stand for 5 minutes, and then the presence or absence of phase separation was visually observed.

The ULTRASONIC dispersion device may be an ULTRASONIC wave dispersion device manufactured by AS ONE, model "ULTRASONIC clean" or a device equivalent thereto.

The amount of the compound a to be used is not particularly limited, and may be set so that the use effect (for example, one or both of the effect of suppressing an increase in peeling force due to exposure to high temperature and the effect of contributing to light peeling by water peeling) according to the purpose can be appropriately exhibited. In some embodiments, the amount of the compound a to be used may be, for example, about 5 parts by weight or less with respect to 100 parts by weight of the base polymer, and is suitably about 3 parts by weight or less, preferably less than 2 parts by weight, more preferably less than 1 part by weight, and may be less than 0.8 part by weight, may be less than 0.6 part by weight, may be less than 0.4 part by weight, may be less than 0.2 part by weight, and may be less than 0.1 part by weight, from the viewpoint of bonding reliability with respect to an adherend in a stage where peeling is not desired, and water-resistant reliability. Compound a having a high HLB (for example, 5 or more, preferably 10 or more) tends to exhibit good water-releasing properties even when added in a small amount. The amount of the compound a may be, for example, 0.001 parts by weight or more based on 100 parts by weight of the base polymer, and is usually preferably 0.01 parts by weight or more, and preferably 0.03 parts by weight or more (for example, 0.1 parts by weight or more), from the viewpoint of allowing the compound a to be uniformly present on the surface of the pressure-sensitive adhesive layer and allowing the pressure-sensitive adhesive sheet to be more smoothly peeled from an adherend. In the composition in which water-releasability is important, the amount of compound a may be 0.3 parts by weight or more (for example, 0.5 parts by weight or more) relative to 100 parts by weight of the base polymer.

(crosslinking agent)

In the pressure-sensitive adhesive layer, a crosslinking agent may be used as necessary for the purpose of adjusting the cohesive force or the like. The crosslinking agent may be contained in the pressure-sensitive adhesive layer in a form after the crosslinking reaction, or may be contained in the pressure-sensitive adhesive layer in a form before the crosslinking reaction. The kind of the crosslinking agent is not particularly limited, and may be selected from conventionally known crosslinking agents, for example, depending on the composition of the adhesive composition so that the crosslinking agent can exert an appropriate crosslinking function in the adhesive layer. Examples of the crosslinking agent that can be used include an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a carbodiimide-based crosslinking agent, a melamine-based crosslinking agent, a urea-based crosslinking agent, a metal alkoxide-based crosslinking agent, a metal chelate-based crosslinking agent, a metal salt-based crosslinking agent, a hydrazine-based crosslinking agent, and an amine-based crosslinking agent. These can be used alone in 1 or a combination of 2 or more. In some preferred embodiments, at least an isocyanate-based crosslinking agent is used as the crosslinking agent. The isocyanate-based crosslinking agent and other crosslinking agents (for example, epoxy-based crosslinking agents) may be used in combination.

As the isocyanate-based crosslinking agent, a polyfunctional isocyanate compound having 2 or more functions can be used. Examples thereof include aromatic isocyanates such as toluene diisocyanate, xylene diisocyanate, polymethylene polyphenyl diisocyanate, tris (p-isocyanatophenyl) thiophosphate, and diphenylmethane diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; aliphatic isocyanates such as 1, 6-hexamethylene diisocyanate; and so on. Examples of commercially available products include isocyanate adducts such as trimethylolpropane/tolylene diisocyanate trimer adduct (product name "Coronate L" manufactured by Tosoh Corporation), trimethylolpropane/1, 6-hexamethylene diisocyanate trimer adduct (product name "Coronate HL" manufactured by Tosoh Corporation), and isocyanurate of 1, 6-hexamethylene diisocyanate (product name "Coronate HX" manufactured by Tosoh Corporation).

As the epoxy-based crosslinking agent, an epoxy-based crosslinking agent having 2 or more epoxy groups in 1 molecule can be used without particular limitation. Preferably an epoxy crosslinking agent having 3 to 5 epoxy groups in 1 molecule. Specific examples of the epoxy-based crosslinking agent include N, N' -tetraglycidyl m-xylylenediamine, 1, 3-bis (N, N-diglycidylaminomethyl) cyclohexane, 1, 6-hexanediol diglycidyl ether, polyethylene glycol diglycidyl ether, and polyglycerol polyglycidyl ether. Commercially available products of the epoxy-based crosslinking agent include trade names "TETRAD-X" and "TETRAD-C" manufactured by Mitsubishi gas chemical Corporation, trade name "EPICLON CR-5L" manufactured by DIC Corporation, trade name "Denacol EX-512" manufactured by Nagase ChemteX Corporation, and trade name "TEPIC-G" manufactured by Nissan chemical industry Corporation.

As the oxazoline-based crosslinking agent, an oxazoline-based crosslinking agent having 1 or more oxazoline groups in 1 molecule can be used without particular limitation.

Examples of the aziridine-based crosslinking agent include trimethylolpropane tris [3- (1-aziridinyl) propionate ], trimethylolpropane tris [3- (1- (2-methyl) aziridinyl propionate ], and the like.

As the carbodiimide-based crosslinking agent, a low molecular weight compound or a high molecular weight compound having 2 or more carbodiimide groups can be used.

The metal chelate crosslinking agent is typically a substance having a structure in which a polyvalent metal and an organic compound are covalently or coordinately bonded to each other. Examples of the polyvalent metal atom include Al, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Ba, Mo, La, Sn, Ti and the like. Among them, Al, Zr and Ti are preferable. Examples of the organic compound include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds. The metal chelate crosslinking agent is typically a compound having a structure in which an oxygen atom in the organic compound is bonded (covalently bonded or coordinately bonded) to the polyvalent metal.

In some embodiments, as the crosslinking agent, a peroxide may be used. Examples of the peroxide include di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, di-sec-butyl peroxydicarbonate, t-butyl peroxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,3, 3-tetramethylbutyl peroxyisobutyrate, and dibenzoyl peroxide. Of these, the peroxides having particularly excellent crosslinking reaction efficiency include bis (4-t-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, dibenzoyl peroxide, and the like. When a peroxide is used as the polymerization initiator, the peroxide remaining without being used in the polymerization reaction may be used in the crosslinking reaction. In this case, the residual amount of the peroxide is quantitatively determined, and when the proportion of the peroxide does not satisfy a predetermined amount, the peroxide may be added to the predetermined amount as needed. The peroxide can be quantified by the method described in Japanese patent No. 4971517.

The amount of the crosslinking agent to be used (the total amount of 2 or more crosslinking agents in the case of using them) is not particularly limited, and may be appropriately set so that a desired use effect can be obtained. From the viewpoint of preventing adhesive residue and suppressing an increase in peeling force due to high-temperature exposure after attachment, the amount of the crosslinking agent used is usually preferably about 0.01 parts by weight or more, preferably about 0.1 parts by weight or more, more preferably about 0.5 parts by weight or more, and may be about 1.0 parts by weight or more, may be about 1.5 parts by weight or more, and may be about 2.0 parts by weight or more, relative to 100 parts by weight of the base polymer (for example, acrylic polymer).

In addition, the amount of the polymer is 100 wt.% based on the base polymerThe amount of the crosslinking agent used in parts is usually preferably about 15 parts by weight or less, and from the viewpoint of adhesion to an adherend during semiconductor processing, bonding reliability, and the like, is preferably about 12 parts by weight or less, and more preferably about 10 parts by weight or less. Attach more importance to the initial normal peel force Fd₀In some embodiments, the crosslinking agent may be used in an amount of, for example, less than 7.0 parts by weight, less than 5.0 parts by weight, less than 4.0 parts by weight, and less than 3.0 parts by weight, relative to 100 parts by weight of the base polymer. In the mode of including the compound a in a certain amount (for example, more than 0.2 part by weight with respect to 100 parts by weight of the base polymer), the initial normal peeling force Fd caused by excessive deflection of the compound a to the surface of the adhesive layer is suppressed without excessively using the amount of the crosslinking agent₀May also become advantageous from the viewpoint of the decline.

In the embodiment using an isocyanate-based crosslinking agent as the crosslinking agent, the amount of the isocyanate-based crosslinking agent used is usually preferably about 0.1 part by weight or more, preferably about 0.5 part by weight or more, more preferably about 0.7 part by weight or more, and may be about 1.0 part by weight or more, and may be about 1.5 parts by weight or more, based on 100 parts by weight of the base polymer, from the viewpoints of preventing adhesive residue and suppressing an increase in peel strength due to high-temperature exposure after the patch.

The amount of the isocyanate-based crosslinking agent used is usually preferably about 15 parts by weight or less based on 100 parts by weight of the base polymer, and from the viewpoints of adhesion to an adherend during semiconductor processing, bonding reliability, and the like, it is preferably about 12 parts by weight or less, more preferably about 10 parts by weight or less, and may be less than 7.0 parts by weight, may be less than 5.0 parts by weight, may be less than 4.0 parts by weight, may be less than 3.0 parts by weight, and may be less than 2.5 parts by weight.

In the embodiment using an epoxy-based crosslinking agent as a crosslinking agent (the embodiment may use an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent in combination), the amount of the epoxy-based crosslinking agent used is usually suitably about 0.01 parts by weight or more, preferably about 0.05 parts by weight or more, more preferably about 0.1 parts by weight or more, and may be about 0.3 parts by weight or more, and may be about 0.5 parts by weight or more, based on 100 parts by weight of the base polymer, from the viewpoint of suppressing an increase in peeling force due to high-temperature exposure after the attachment. In a preferred embodiment, the amount of the epoxy crosslinking agent used may be, for example, more than 0.5 part by weight and 0.6 part by weight or more relative to 100 parts by weight of the base polymer.

From the viewpoints of adhesion to an adherend and bonding reliability during semiconductor processing, the amount of the epoxy-based crosslinking agent used is usually preferably about 5 parts by weight or less, preferably about 3 parts by weight or less, more preferably about 2 parts by weight or less, and may be 1.5 parts by weight or less, and may be 1.0 part by weight or less, per 100 parts by weight of the base polymer.

When the isocyanate-based crosslinking agent and the epoxy-based crosslinking agent are used in combination, the amount W of the epoxy-based crosslinking agent used_EPOAmount W used relative to the amount of isocyanate-based crosslinking agent_NCORatio of (weight ratio W)_EPO：W_NCO) For example, it may be 0.005:1 or more and 2:1 or less, and usually preferably 0.01:1 or more and 1:1 or less, preferably more than 0.10:1 and 0.80:1 or less, and more preferably more than 0.25:1 and 0.60:1 or less (for example, 0.30:1 or more and 0.50:1 or less).

In order to allow the crosslinking reaction to proceed more efficiently, a crosslinking catalyst may be used. Examples of the crosslinking catalyst include metal-based crosslinking catalysts such as tetra-n-butyl titanate, tetra-isopropyl titanate, iron acetylacetonate, butyltin oxide, and dioctyltin dilaurate. Among them, tin-based crosslinking catalysts such as dioctyltin dilaurate are preferable. The amount of the crosslinking catalyst used is not particularly limited. The amount of the crosslinking catalyst used may be, for example, about 0.0001 part by weight or more and 1 part by weight or less, 0.001 part by weight or more and 0.1 part by weight or less, and 0.005 part by weight or more and 0.5 part by weight or less, relative to 100 parts by weight of the base polymer.

(other optional ingredients)

The pressure-sensitive adhesive layer may contain, as other optional components, various additives that are conventional in the field of pressure-sensitive adhesives, such as a tackifier resin (e.g., rosin-based, petroleum-based, terpene-based, phenol-based, ketone-based, etc.), a viscosity modifier (e.g., a tackifier), a leveling agent, a plasticizer, a filler, a colorant such as a pigment, a dye, etc., a stabilizer, a preservative, an antioxidant, and an antioxidant. Such various additives may be conventionally used, and since they are not particularly specific to the present invention, they are not described in detail.

From the viewpoint of achieving both of the adhesion to an adherend during semiconductor processing and the peelability at the time of removal of the adherend (for example, peelability by water peeling) with good balance, the content of the tackifier resin in the pressure-sensitive adhesive layer may be, for example, less than 5 parts by weight, further may be less than 3 parts by weight, may be less than 1 part by weight, may be less than 0.5 part by weight, and may be less than 0.1 part by weight, based on 100 parts by weight of the base polymer in some embodiments. The pressure-sensitive adhesive layer may be substantially free of a tackifier resin (for example, the content of the pressure-sensitive adhesive layer is 0 to 0.05 parts by weight relative to 100 parts by weight of the base polymer).

In some preferred embodiments, the adhesive layer may be composed of a polymer (typically, a base polymer) in an amount of about 80 wt% or more based on the total weight of the adhesive layer. This can desirably achieve an effect of reducing the peeling force by peeling with water (light peeling effect). From such a viewpoint, the content of the polymer is preferably about 85 wt% or more, more preferably about 90 wt% or more, may be about 92 wt% or more, may be about 95 wt% or more, and may be about 98 wt% or more of the total weight of the pressure-sensitive adhesive layer.

In some other embodiments of the pressure-sensitive adhesive sheet disclosed in the present specification, the pressure-sensitive adhesive sheet may have a pressure-sensitive adhesive surface comprising an active energy ray (preferably ultraviolet ray) -curable pressure-sensitive adhesive layer, that is, an active energy ray-curable pressure-sensitive adhesive layer. The active energy ray-curable adhesive layer may be an adhesive layer containing, as a base polymer, an active energy ray-curable polymer (for example, an acrylic polymer) having a curable functional group at least any one position of a side chain, a main chain, and a main chain end. Another example of the active energy ray-curable adhesive layer is an adhesive layer containing a monomer or oligomer having 2 or more curable functional groups in the molecule. Examples of the above-mentioned polymer, monomer and oligomer that can be used for the purpose of making the pressure-sensitive adhesive layer active energy ray-curable include a polymer having a functional group having a carbon-carbon double bond in a side chain (e.g., (meth) acryloyl group, vinyl group, etc.), a polyfunctional (meth) acrylate (e.g., trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, etc.), an isocyanate compound having a carbon-carbon double bond (e.g., (meth) acrylic acid 2-isocyanatoethyl ester, m-isopropenyl- α, α -dimethylbenzyl isocyanate, etc.), a urethane oligomer, a urethane (meth) acrylate, etc., but are not limited to these. If necessary, a known photoinitiator may be contained in the active energy ray-curable adhesive layer.

The pressure-sensitive adhesive sheet disclosed in the present specification preferably has a pressure-sensitive adhesive surface comprising a pressure-sensitive adhesive layer that is not curable by active energy rays (non-active energy ray-curable pressure-sensitive adhesive layer). The pressure-sensitive adhesive sheet having the pressure-sensitive adhesive surface comprising the actinic energy ray-curable pressure-sensitive adhesive layer has excellent performance stability against irradiation with actinic energy rays (e.g., ultraviolet rays), and is also preferably applicable to a use mode involving a semiconductor processing process involving irradiation with actinic energy rays.

< formation of adhesive layer >

The adhesive layer constituting the adhesive surface of the adhesive sheet disclosed in the present specification may be an adhesive layer formed from an adhesive composition containing a base polymer (for example, an acrylic polymer) and, if necessary, other optional components. The adhesive composition may be in the following forms: a solvent-based adhesive composition containing an adhesive (adhesive component) in an organic solvent; an active energy ray-curable adhesive composition prepared so as to be cured by an active energy ray such as ultraviolet ray or radioactive ray to form an adhesive; an aqueous dispersion type adhesive composition in which an adhesive is dispersed in water; a hot-melt adhesive composition which forms an adhesive when applied in a molten state by heating and cooled to a temperature around room temperature; and so on. The active energy ray-curable adhesive composition is typically a liquid composition which exhibits fluidity at room temperature (about 0 to 40 ℃, for example, about 25 ℃) to the extent that it can be applied and which forms an adhesive (viscoelastic body) by curing upon irradiation with an active energy ray.

The adhesive sheet according to some embodiments may have a structure having an adhesive layer formed using a solvent-based adhesive composition or an active energy ray-curable adhesive composition. In the embodiment in which the adhesive layer contains the compound a, a solvent-based adhesive composition can be preferably used from the viewpoint of ease of preparation of the adhesive composition containing the compound a.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet disclosed in the present specification can be formed by applying (for example, coating) a pressure-sensitive adhesive composition to an appropriate surface and then appropriately performing a curing treatment (drying, crosslinking, or the like). In the case of performing 2 or more curing treatments, they may be performed simultaneously or in multiple steps. The adhesive layer of the multilayer structure having two or more layers can be produced by bonding previously formed adhesive layers. Alternatively, an adhesive composition may be applied on a previously formed first adhesive layer and cured to form a second adhesive layer.

The application of the adhesive composition can be carried out using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, or a spray coater. In the psa sheet having the form of a support, as a method for providing a psa layer on a support, a direct method of forming a psa layer by directly applying a psa composition to the support may be used, or a transfer method of transferring a psa layer formed on a release surface to a support may be used.

In the pressure-sensitive adhesive sheet disclosed in the present specification, the thickness of the pressure-sensitive adhesive layer is not particularly limited and may be appropriately selected according to the purpose. The thickness of the pressure-sensitive adhesive layer is usually preferably about 5 to 200 μm, and from the viewpoint of adhesion and the like, it is preferably 10 μm or more, for example, about 15 μm or more, preferably 150 μm or less, more preferably 100 μm or less, further preferably 80 μm or less, and for example, may be 60 μm or less. In some embodiments, the thickness of the pressure-sensitive adhesive layer may be, for example, 40 μm or less, 30 μm or less, or 25 μm or less, from the viewpoint of easily suppressing an increase in the peeling force due to heating. In the case where the pressure-sensitive adhesive sheet disclosed in the present specification is a double-sided pressure-sensitive adhesive sheet having pressure-sensitive adhesive layers on both sides of a substrate, the thicknesses of the pressure-sensitive adhesive layers may be the same or different.

< additional adhesive layer >

In some embodiments of the pressure-sensitive adhesive sheet disclosed in the present specification, the pressure-sensitive adhesive sheet may have a structure in which an additional pressure-sensitive adhesive layer is laminated on the back side (the side opposite to the pressure-sensitive adhesive surface) of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive surface. The pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive surface and the additional pressure-sensitive adhesive layer are preferably laminated in direct contact with each other. That is, it is preferable that a separator layer (for example, a resin film such as a polyester film) completely separating the two pressure-sensitive adhesive layers does not exist between the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive surface and the additional pressure-sensitive adhesive layer. The additional pressure-sensitive adhesive layer may be a pressure-sensitive adhesive layer containing 1 or 2 or more kinds of pressure-sensitive adhesives selected from known various pressure-sensitive adhesives such as acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives (natural rubber-based, synthetic rubber-based, and mixed systems thereof), silicone pressure-sensitive adhesives, polyester pressure-sensitive adhesives, urethane pressure-sensitive adhesives, polyether pressure-sensitive adhesives, polyamide pressure-sensitive adhesives, and fluorine pressure-sensitive adhesives. In some embodiments, an acrylic adhesive is preferably used as a constituent material of the additional adhesive layer from the viewpoint of transparency, weatherability, and the like. Other matters related to the additional pressure-sensitive adhesive layer may be configured in the same manner as the above-described pressure-sensitive adhesive layer, or may be configured appropriately according to the application and purpose based on known or customary techniques and technical common knowledge, and therefore, a detailed description thereof will be omitted here.

< substrate >

In the substrate-attached pressure-sensitive adhesive sheet of the single-sided pressure-sensitive adhesive type or the double-sided pressure-sensitive adhesive type, various sheet-shaped substrates such as a resin film, paper, cloth, a rubber sheet, a foam sheet, a metal foil, and a composite thereof can be used as a substrate for supporting (lining) the pressure-sensitive adhesive layer. The substrate may be a single layer or a laminate of substrates of the same or different types. In the present specification, the term "single layer" refers to a layer having the same composition, and includes a layer in which a plurality of layers having the same composition are stacked.

In a preferred embodiment, a base material (resin film base material) mainly composed of a resin sheet is used. Examples of the resin constituting the base material include polyolefin resins such as low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, ultra-low-density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homo polypropylene, polybutene, polymethylpentene, ethylene-vinyl acetate copolymer (EVA), ionomer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer, and ethylene-hexene copolymer; a polyurethane; polyesters such as polyethylene terephthalate (PET), polyethylene naphthalate, and polybutylene terephthalate (PBT); a polycarbonate; a polyimide; polyether ether ketone; a polyetherimide; polyamides such as aromatic polyamides and wholly aromatic polyamides; polyphenylene sulfide; a fluororesin; polyvinyl chloride; polyvinylidene chloride; a cellulose resin; a polysiloxane resin; and so on. The above-mentioned resins may be used singly or in combination of two or more for the formation of the whole or a part of the base material (for example, any one of two or more layers of the base material in a laminated structure).

Various additives such as fillers (inorganic fillers, organic fillers, etc.), antioxidants, ultraviolet absorbers, antistatic agents, lubricants, plasticizers, colorants (pigments, dyes, etc.), and the like may be blended into the base material as necessary.

The substrate can be manufactured by any suitable method. For example, the resin composition can be produced by a known method such as a rolling method, a casting method, an expansion extrusion method, and a T-die extrusion method. Further, if necessary, the film can be produced by stretching.

For the purpose of improving adhesion to the pressure-sensitive adhesive layer, holding property of the pressure-sensitive adhesive layer, and the like, physical treatments such as corona discharge treatment, plasma treatment, sand cushion processing treatment, ozone exposure treatment, flame exposure treatment, high-voltage shock exposure treatment, ionizing radiation treatment, and the like may be applied to the pressure-sensitive adhesive layer-side surface of the base material; chemical treatments such as acid treatment, alkali treatment, chromic acid treatment and the like; known or conventional surface treatments such as easy adhesion treatment based on coating agents (primers). Further, for the purpose of imparting antistatic ability or the like, a conductive vapor deposition layer containing a metal, an alloy, an oxide thereof, or the like may be provided on the surface of the base material.

In some preferred embodiments, a primer layer may be provided on the adhesive layer-side surface of the substrate. In other words, the primer layer may be disposed between the substrate and the adhesive layer. The undercoat layer forming material is not particularly limited, and 1 or 2 or more of urethane (polyisocyanate) resin, polyester resin, acrylic resin, polyamide resin, melamine resin, olefin resin, polystyrene resin, epoxy resin, phenol resin, isocyanurate resin, polyvinyl acetate resin, and the like can be used. When an acrylic pressure-sensitive adhesive layer or the like is provided on the resin film substrate with a primer layer interposed therebetween, a polyester-based, urethane-based, or acrylic primer layer is preferable. When an acrylic pressure-sensitive adhesive layer is provided on a polyester substrate such as a PET film with a primer layer interposed therebetween, the polyester primer layer is particularly preferable. The thickness of the undercoat layer is not particularly limited, and may be usually in the range of about 0.1 to 10 μm (for example, 0.1 to 3 μm, and typically 0.1 to 1 μm). The undercoat layer can be formed by using a known or conventional coater such as a gravure roll coater or a reverse roll coater.

In the case where the pressure-sensitive adhesive sheet disclosed in the present specification is a one-sided pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer provided on one surface of a substrate, the pressure-sensitive adhesive layer non-formation surface (back surface) of the substrate may be subjected to a peeling treatment using a peeling treatment agent (back surface treatment agent). The back surface treatment agent that can be used for forming the back surface treatment layer is not particularly limited, and known or conventional treatment agents such as a polysiloxane-based back surface treatment agent, a fluorine-based back surface treatment agent, and a long chain alkyl-based back surface treatment agent can be used according to the purpose and the application.

The thickness of the substrate is not particularly limited and may be appropriately selected according to the purpose, and may be usually about 3 μm to 800 μm. The thickness of the substrate is preferably 5 μm or more, preferably 10 μm or more from the viewpoint of processability and workability of the pressure-sensitive adhesive sheet (for example, workability in attaching to and detaching from an adherend), and is preferably 20 μm or more, may be 30 μm or more, and may be 40 μm or more from the viewpoint of improving the protection of the adherend. In some embodiments where protection is more important, the thickness of the substrate may be, for example, 55 μm or more, 75 μm or more, or 90 μm or more. In addition, the thickness of the base material is usually preferably 300 μm, preferably 200 μm or less, and may be 150 μm or less, 125 μm or less, 80 μm or less, and may be 60 μm or less, from the viewpoint of reducing the load on the adherend when peeled off from the adherend.

The total thickness of the adhesive sheet (which may include the adhesive layer and the substrate, but does not include the release liner) disclosed in the present specification is not particularly limited, and is preferably in the range of about 10 μm to 1000 μm. In view of adhesion and handling properties, the total thickness of the pressure-sensitive adhesive sheet is preferably in the range of about 15 to 300 μm, more preferably in the range of about 20 to 300 μm, and may be in the range of 20 to 200 μm. From the viewpoint of improving the protection of the adherend, the total thickness of the pressure-sensitive adhesive sheet is favorably about 30 μm or more, preferably about 40 μm or more, and more preferably about 50 μm or more (for example, 60 μm or more). In some ways where protection is more important, the total thickness of the adhesive sheet may be greater than 65 μm, may be greater than 80 μm, and may be greater than 100 μm.

< adhesive sheet >

(initial conventional Peel force Fd₀)

Initial conventional peeling force Fd of the adhesive sheet disclosed in this specification₀Preferably 0.10N/20mm or more. Thus, the adhesive sheet exhibits appropriate adhesiveness as an adhesive sheet for semiconductor processing, and can contribute to improvement in processability. For example, the pressure-sensitive adhesive sheet disclosed in the present specification is used for back grinding for protecting a circuit-formed surface of a semiconductor wafer (adherend) in a back grinding step of the semiconductor waferWhen the adhesive tape is used, peeling of the adhesive sheet and breakage of the semiconductor wafer during back grinding can be prevented. Initial conventional peel force Fd₀The upper limit of (B) is not particularly limited, but is usually preferably less than 1.00N/20mm, more preferably 0.60N/20mm or less, and may be 0.40N/20mm or less, and may be 0.30N/20mm or less, from the viewpoint of easily suppressing the peeling force after heating to a predetermined value or less. Initial conventional peel force Fd₀The measurement can be carried out by the above-mentioned method, more specifically, the method described in the examples described later. Initial conventional peel force Fd₀Can be adjusted by the choice of the base polymer, the choice of the type and amount of compound A when it is used, the choice of the type and amount of cross-linking agent when it is used, etc.

(conventional peeling force Fd_a)

General peeling force Fd of the adhesive sheet disclosed in this specification_a(conventional peeling force after heating at 150 ℃) is preferably 1.00N/20mm or less. Thus, even if the pressure-sensitive adhesive sheet is exposed to high temperatures after being attached to an adherend, an increase in the load applied to the adherend upon subsequent peeling can be suppressed. By peeling the adherend by the water peeling method, the load on the adherend can be further reduced. In some embodiments, the ordinary peeling force after heating at 150 ℃ is more preferably 0.60N/20mm or less, and still more preferably 0.40N/20mm or less, from the viewpoint of reducing the load on the adherend at the time of peeling. The lower limit of the ordinary peeling force after heating at 150 ℃ is not particularly limited, and may be, for example, 0.005N/20mm or more, 0.01N/20mm or more, or 0.02N/20mm or more, from the viewpoint of achieving a balance between the adhesion to an adherend during processing and the bonding reliability. The ordinary peel force after heating at 150 ℃ can be measured by the above-mentioned method, more specifically, the method described in the examples described later. The conventional peeling force after heating at 150 ℃ can be adjusted by selection of the base polymer, selection of the kind and amount of the compound A when the compound A is used, selection of the kind and amount of the crosslinking agent when the crosslinking agent is used, and the like.

Note that even the normal peeling force Fd_aAbove any upper limit valueIf the pressure-sensitive adhesive sheet of (3) is a type that can be peeled off with water to achieve sufficient light peeling (for example, if the water peeling force Fw_a0.40N/20mm or less, more preferably 0.30N/20mm or less), the pressure-sensitive adhesive sheet can be appropriately inhibited from being subjected to a load or adhesive residue on an adherend by peeling off the pressure-sensitive adhesive sheet after heating by a water peeling method. Therefore, in the above manner, the conventional peeling force Fd of the adhesive sheet_aMay be greater than 1.00N/20 mm. Normal peel force Fd of the adhesive sheet in this manner_aThe thickness is not particularly limited, and may be, for example, 2.00N/20mm or less or 1.00N/20mm or less.

(conventional peeling force Fd_b)

General peeling force Fd of the adhesive sheet disclosed in this specification_b(conventional peeling force after heating at 200 ℃) is preferably 3.00N/20mm or less. Thereby, even when exposed to a high temperature under severer conditions, an increase in load applied to the adherend at the time of subsequent peeling can be suppressed. By peeling from the adherend by the water peeling method, the load on the adherend during peeling can be further reduced. In some embodiments, the ordinary peeling force after heating at 200 ℃ is more preferably 2.00N/20mm or less, 1.50N/20mm or less, 1.20N/20mm or less, or 1.00N/20mm or less from the viewpoint of reducing the load on the adherend at the time of peeling. The lower limit of the ordinary peeling force after heating at 200 ℃ is not particularly limited, and may be, for example, 0.01N/20mm or more, 0.02N/20mm or more, or 0.03N/20mm or more, from the viewpoint of achieving a balance between the adhesion to an adherend during processing and the bonding reliability. The ordinary peel force after heating at 200 ℃ can be measured by the above-mentioned method, more specifically, the method described in the examples described later. The conventional peeling force after heating at 200 ℃ can be adjusted by selection of the base polymer, selection of the kind and amount of the compound A when the compound A is used, selection of the kind and amount of the crosslinking agent when the crosslinking agent is used, and the like.

Note that even the normal peeling force Fd_bIf the pressure-sensitive adhesive sheet is higher than any of the above upper limit values, it may be a system that can achieve sufficient light peeling by water peeling (for example, if the water peeling force Fw_b2.00N/20mm or less, preferably 1.00N/20mm or less), the pressure-sensitive adhesive sheet can be appropriately inhibited from being subjected to a load or adhesive residue on an adherend by peeling the pressure-sensitive adhesive sheet after heating by a water peeling method. Therefore, in the above manner, the conventional peeling force Fd of the adhesive sheet_bMay be greater than 3.00N/20 mm. Normal peel force Fd of the adhesive sheet in this manner_bThe thickness is not particularly limited, and may be, for example, 5.00N/20mm or less or 4.00N/20mm or less.

(Water peeling force Fw)_a)

Water peeling force Fw of the pressure-sensitive adhesive sheet disclosed in the present specification_a(water peeling force after heating at 150 ℃) is preferably 0.30N/20mm or less. Thus, even if the pressure-sensitive adhesive sheet is exposed to high temperatures after being attached to an adherend, the load on the adherend can be suppressed by performing subsequent peeling by a water peeling method. In some embodiments, the water peeling force after heating at 150 ℃ is more preferably less than 0.30N/20mm, and still more preferably 0.25N/20mm or less, from the viewpoint of reducing the load on the adherend at the time of peeling. The lower limit of the water-peeling force after heating at 150 ℃ is not particularly limited, and may be, for example, 0.01N/20mm or more, 0.05N/20mm or more, or 0.01N/20mm or more, from the viewpoint of achieving a balance between the adhesion to an adherend during processing and the bonding reliability. The water peeling force after heating at 150 ℃ can be measured by the above-mentioned method, more specifically, the method described in the examples described later. The water-peeling force after heating at 150 ℃ can be adjusted by the selection of the base polymer, the selection of the kind and amount of the compound A when the compound A is used, the selection of the kind and amount of the crosslinking agent when the crosslinking agent is used, and the like.

(Water peeling force Fw)_b)

Water peeling force Fw of the pressure-sensitive adhesive sheet disclosed in the present specification_b(water peeling force after heating at 200 ℃) is preferably 2.00N/20mm or less. Thus, even when exposed to a high temperature under severer conditions, the load on the adherend can be suppressed by performing the subsequent peeling by the water peeling method. In some embodiments, the water peeling force after heating at 200 ℃ may be 1.50N/20mm or less, 1.00N/20mm or less from the viewpoint of reducing the load on the adherend at the time of peelingLower, less than 0.80N/20mm or less than 0.60N/20 mm. The lower limit of the water-peeling force after heating at 200 ℃ is not particularly limited, and may be, for example, 0.05N/20mm or more, 0.01N/20mm or more, or 0.03N/20mm or more, from the viewpoint of achieving a balance between the adhesion to an adherend during processing and the bonding reliability. The water peeling force after heating at 200 ℃ can be measured by the above-mentioned method, more specifically, the method described in the examples described later. The water-peeling force after heating at 200 ℃ can be adjusted by the selection of the base polymer, the selection of the kind and amount of the compound A when the compound A is used, the selection of the kind and amount of the crosslinking agent when the crosslinking agent is used, and the like.

(conventional peeling force ratio Fd_b/Fd_a)

As the conventional peeling force after heating at 200 ℃ for the adhesive sheet disclosed in the present specification, [ N/20mm ]]Relative to the conventional peeling force after heating at 150 ℃ [ N/20mm]Ratio of (Fd)_b/Fd_a) And the defined conventional peeling force ratio is preferably 4.0 or less. Accordingly, the pressure-sensitive adhesive sheet is not susceptible to the peeling force after the high-temperature process, which may be caused by temperature unevenness. The pressure-sensitive adhesive sheet is preferably used because the risk of adhesive residue when peeling the pressure-sensitive adhesive sheet subjected to a high-temperature process in a state of being attached to an adherend can be reduced, and the load on the adherend due to the variation in peel force can be reduced. From the viewpoint of further reducing the influence of the temperature unevenness, the conventional peeling force ratio is more preferably 3.5 or less, and still more preferably 3.0 or less. Conventional peel force ratios are typically 1.0 or greater.

(conventional Peel force Difference Fd_b-Fd_a)

As a conventional peeling force after heating at 150 ℃ for the adhesive sheet disclosed in the present specification, [ N/20mm ]]Normal peel force [ N/20mm ] after heating at 200 deg.C]Difference between (Fd)_b-Fd_a) And the defined conventional peeling force difference is preferably 1.50N/20mm or less. Accordingly, the pressure-sensitive adhesive sheet is not susceptible to the peeling force after the high-temperature process, which may be caused by temperature unevenness. The adhesive sheet is to be attached to a subjectWhen the pressure-sensitive adhesive sheet is peeled off in a high-temperature process in the state of an adherend, the risk of adhesive residue can be reduced, and the load on the adherend due to the variation in peeling force can be reduced, which is preferable. From the viewpoint of further reducing the influence of the temperature unevenness, the conventional peeling force difference is more preferably 1.20N/20mm or less, may be 1.00N/20mm or less, may be 0.80N/20mm or less, and may be 0.60N/20mm or less. Since the difference in the normal peeling force after heating is usually 0N/20mm or more, the lower limit is not particularly limited, and the closer to 0N/20mm, the more preferable.

(initial Water peeling force Fw₀)

Initial water peeling force Fw of the adhesive sheet disclosed in the present specification₀Preferably less than 0.10N/20 mm. Thus, in the case of the pressure-sensitive adhesive sheet used in, for example, semiconductor processing which does not involve a high-temperature process (for example, a high-temperature process of 100 ℃ or higher, preferably 60 ℃ or higher), the pressure-sensitive adhesive sheet can be appropriately subjected to light peeling by a water peeling method, and the load applied to an adherend at the time of peeling can be reduced. Thus, for example, in the case of an adhesive sheet that can be used as a back-grinding tape, the adhesive sheet can be efficiently peeled from a semiconductor wafer thinned by back-grinding while avoiding damage to the semiconductor wafer. In some embodiments, the initial water peel force Fw₀More preferably less than 0.09N/20mm, and may be 0.07N/20mm or less, and may be less than 0.05N/20 mm. Initial water peel force Fw₀The lower limit of (b) is not particularly limited, but is preferably smaller from the viewpoint of reducing the load on the adherend. On the other hand, in some embodiments, the initial water peeling force Fw is set in order to balance the adhesion to the adherend and the bonding reliability during processing₀For example, it may be 0.005N/20mm or more, 0.01N/20mm or more, 0.02N/20mm or more, or 0.03N/20mm or more. Initial water peel force Fw₀The measurement can be carried out by the above-mentioned method, more specifically, the method described in the examples described later. Initial water peel force Fw₀Can be determined by selection of the base polymer, selection of the type and amount of the compound A when the compound A is used, selection of the type and amount of the crosslinking agent when the crosslinking agent is used, and the likeTo adjust.

As the tensile tester used for measuring the above-mentioned conventional peeling force and water peeling force, a precision universal tester "Autograph EZ-S" manufactured by Shimadzu corporation or a device corresponding thereto can be used. In the measurement, an appropriate lining material (for example, a PET film having a thickness of about 25 μm) may be attached to the pressure-sensitive adhesive sheet to be measured and reinforced as necessary.

In the examples described later, the measurement of the normal peeling force and the measurement of the water peeling force were continuously performed for each test piece, but the measurement of the normal peeling force and the measurement of the water peeling force may be performed using different test pieces. For example, in the case where it is difficult to prepare a test piece having a length sufficient for continuous measurement, a method of measuring using a different test piece can be employed.

In some preferred embodiments of the pressure-sensitive adhesive sheet disclosed in the present specification, the water peeling force Fw after heating at 200 ℃_b[N/20mm]Relative to the conventional peel force Fd after heating at 200 ℃_b[N/20mm]The rate of decrease of (c) may be, for example, greater than 30%. That is, the rate of decrease in water peeling force after heating at 200 ℃ is preferably 10% or more as calculated by the following formula.

The rate of decrease in water peeling force after heating at 200 ℃ is 1- (Fw)_b/Fd_b)

Even when the peeling force is increased by heating after bonding and then peeling is performed by the water peeling method, the peeling force can be greatly reduced as compared with the case of peeling by the conventional peeling method, and the load applied to the adherend at the time of peeling can be effectively reduced. In the pressure-sensitive adhesive sheet according to some preferred embodiments, the rate of decrease in the water peeling force after heating at 200 ℃ may be 15% or more, 25% or more, or 30% or more. The upper limit of the rate of decrease in the water peeling force after heating at 200 ℃ is not particularly limited, but is usually 100% or less, and from the viewpoint of practical use, for example, 95% or less, and may be 90% or less.

< use >)

The adhesive sheet disclosed in the present specification can be used for processing various semiconductor wafers. The semiconductor wafer may be, for example, a silicon wafer, a silicon carbide (SiC) wafer, a nitride semiconductor wafer (silicon nitride (SiN), gallium nitride (GaN), or the like), a compound semiconductor wafer such as a gallium arsenide wafer, or the like. The adhesive sheet disclosed in the present specification can be preferably used as an adhesive sheet for semiconductor processing for protecting and/or fixing a semiconductor wafer during processing of the semiconductor wafer, in a process of manufacturing a semiconductor element (for example, a semiconductor chip) from such a semiconductor wafer, typically in a mode of bonding the adhesive sheet to the semiconductor wafer on which a circuit is formed through a preceding step. Examples of processing that can be performed on a semiconductor wafer after the adhesive sheet disclosed in the present specification is attached and before the adhesive sheet is peeled off include, but are not limited to, back grinding and dicing. In the present specification, when the shape of a semiconductor wafer to be processed is changed by processing (for example, thinning of the whole or part of the wafer by back grinding processing, dicing, or the like), the processed product may be referred to as a semiconductor wafer.

The adhesive sheet disclosed in the present specification can be bonded to a semiconductor wafer by any appropriate method. The temperature at which the adhesive sheet is bonded may be about room temperature (e.g., 10 ℃ C. to 35 ℃ C.), or may be higher than room temperature (e.g., higher than 35 ℃ C., preferably 60 ℃ C. to 90 ℃ C.). When the adhesive sheet is bonded at a temperature higher than the room temperature range, it is advantageous from the viewpoint of improving the adhesion of the adhesive sheet to the semiconductor wafer. After the adhesive sheet is bonded at room temperature, a heat and pressure treatment can be performed to apply a temperature higher than room temperature (e.g., 40 ℃ to 90 ℃, preferably 40 ℃ to 60 ℃) and a pressure higher than atmospheric pressure (e.g., 1.5 atm to 10atm, preferably 3 atm to 7 atm). The time for performing the heat-pressure treatment is not particularly limited, and may be set so that an appropriate treatment effect can be obtained. In some embodiments, the time for performing the heat and pressure treatment may be set to 3 minutes to 1 hour (for example, 5 minutes to 30 minutes) in consideration of the balance between the stability of the treatment effect and the productivity.

The pressure-sensitive adhesive sheet disclosed in the present specification satisfies the above-mentioned condition a and at least one of the conditions B to E, and therefore can be satisfactorily peeled from an adherend even when exposed to a high temperature during the period from the attachment to the adherend to the peeling thereof, and can suppress adhesive residue and a load on the adherend, for example. The adhesive sheet disclosed in the present specification can be preferably used in the following manner by effectively utilizing the above advantages: a method in which a high-temperature process is performed after the adhesive is attached to an adherend until the adhesive is peeled off from the adherend. Non-limiting examples of the high-temperature process include an ion implantation step for a semiconductor wafer, an ashing (ashing) step for removing a resist, and an annealing step such as laser annealing. Such a high-temperature process can be performed, for example, before and/or after the back grinding process in a state where a pressure-sensitive adhesive sheet (back grinding tape) for semiconductor processing used in the back grinding process is attached. Therefore, the adhesive sheet disclosed in the present specification can be preferably used as an adhesive sheet for semiconductor processing used in the following manner: a back grinding step and a high-temperature process (which is performed before and/or after the back grinding step) are included between the step of bonding the adhesive to the adherend and the step of peeling the adhesive from the adherend.

The pressure-sensitive adhesive sheet disclosed in the present specification can be peeled off from an adherend by a conventional peeling method (i.e., a peeling method using no aqueous peeling liquid such as water), or by a water peeling method. In some embodiments, a water stripping method may be preferably used from the viewpoint of improving the strippability. As the aqueous stripping liquid used in the water stripping method, a liquid containing water or a mixed solvent mainly containing water and, if necessary, a small amount of an additive can be used. As the solvent other than water constituting the mixed solvent, a lower alcohol (e.g., ethanol), a lower ketone (e.g., acetone), or the like which can be uniformly mixed with water can be used. As the additive, a known surfactant, pH adjuster, or the like can be used. In some embodiments, it is preferable to use an aqueous release solution substantially free of additives from the viewpoint of avoiding contamination of an adherend. From the viewpoint of environmental hygiene, water is particularly preferably used as the aqueous stripping liquid. The water is not particularly limited, and for example, distilled water, ion-exchanged water, tap water, or the like can be used in consideration of purity, ease of use, and the like required according to the application.

< method for manufacturing semiconductor device >

One embodiment of a method for manufacturing a semiconductor device using the adhesive sheet disclosed in the present specification will be described below. The method for manufacturing a semiconductor device according to this embodiment includes the steps of: a step (1) of bonding the adhesive surface of a semiconductor processing adhesive sheet to the circuit-formed surface side of a semiconductor wafer having the circuit-formed surface; a step (2) of processing the semiconductor wafer to which the adhesive sheet is bonded from the side opposite to the adhesive sheet; and (3) peeling the adhesive sheet from the processed semiconductor wafer.

The step (3) is preferably performed by supplying an aqueous release solution to a release front of the adhesive sheet released from the processed semiconductor wafer (adherend). This makes it possible to lightly peel the pressure-sensitive adhesive sheet, thereby suppressing adhesive residue and reducing the load on the adherend (processed semiconductor wafer). In some embodiments, the step (3) may be preferably performed by a method of peeling off the adhesive sheet described later.

Preferably, the high-temperature process is performed after the step (1) and before the step (3). After the step (1) and before the step (3), a process involving irradiation with an active energy ray (e.g., ultraviolet ray) may be performed. The high-temperature process and the active energy ray irradiation process may be performed in the step (2), may be performed before the step (2), or may be performed after the step (2).

In some embodiments, the step (2) may be a back grinding step. In this case, the adhesive sheet can be used as a back-grinding tape. The back grinding step may be performed by any suitable method. The back grinding step may be a step of: the semiconductor wafer to which the adhesive sheet is bonded is thinned until the thickness of the semiconductor wafer becomes, for example, 150 μm or less, 100 μm or less, 50 μm or less, or 30 μm or less. As described above, in the case of the embodiment of the present invention, the effect of water peeling of the pressure-sensitive adhesive sheet in the step (3) can be exhibited suitably. The back-grinding step may be performed so that the inside of the annular convex portion becomes a concave portion (that is, so that a TAIKO (registered trademark) wafer can be obtained). In this case, the thickness of the thinned semiconductor wafer is the thickness of the recess. Although not particularly limited, the thickness of the semiconductor wafer before back grinding may be, for example, about 500 μm to 1000 μm.

The method for manufacturing a semiconductor device disclosed in the present specification may further include any appropriate step. Examples of such arbitrary processes include, but are not limited to, an etching process, a photolithography process, an ion implantation process, a dicing process, a die bonding process, a wire bonding process, a packaging process, and the like. The respective steps exemplified above may be performed in the step (2), may be performed after the step (2), before the step (3), or may be performed after the step (3).

< method for peeling adhesive sheet >

According to the present specification, there is provided a method for peeling a pressure-sensitive adhesive sheet attached to an adherend from the adherend. The method may include a water peeling step of peeling the adhesive sheet from the adherend while allowing the aqueous peeling liquid to enter the interface of the adherend and the adhesive sheet following the movement of the peeling front in a state where the aqueous peeling liquid is present at the interface of the adherend and the adhesive sheet at the peeling front of the adhesive sheet from the adherend. The peeling front here means a position at which the pressure-sensitive adhesive sheet starts to separate from the adherend when the pressure-sensitive adhesive sheet is peeled from the adherend. The aqueous peeling solution can be used effectively to peel the adhesive sheet from the adherend in the water peeling step. The above-described peeling method can be preferably carried out, for example, in such a manner that any of the pressure-sensitive adhesive sheets disclosed in the present specification is peeled from an adherend.

The adherend in the peeling method disclosed in the present specification may be any of the various semiconductor wafers exemplified above. The semiconductor wafer may be a semiconductor wafer on which a circuit is formed. The peeling method disclosed in the present specification can be preferably used as a method of peeling an adhesive sheet that has been stuck to the circuit-formed surface of a semiconductor wafer having a circuit formed thereon, from the circuit-formed surface. After the pressure-sensitive adhesive sheet is attached to an adherend, a high-temperature process may be performed before the water peeling starts.

As the pressure-sensitive adhesive sheet that can be peeled from an adherend by the above peeling method, any of the pressure-sensitive adhesive sheets disclosed in the present specification can be preferably used. Therefore, the above-described peeling method is suitable as any one of the methods for peeling a pressure-sensitive adhesive sheet disclosed in the present specification.

In some embodiments, the above-described peeling method may preferably be performed by a method including the steps of: forcibly lifting the pressure-sensitive adhesive sheet from an adherend at one end of the outer edge of the pressure-sensitive adhesive sheet attached to the adherend, thereby forming an initial peeling front; supplying an aqueous stripping solution to the stripping front; and peeling the adhesive sheet from the adherend while allowing the aqueous peeling liquid to enter the interface between the adhesive sheet and the adherend following the movement of the peeling front. The formation of the above-mentioned initial peeling front can be carried out, for example, by: inserting a tip of a tool such as a cutter or a needle into an interface between the adhesive sheet and an adherend; grasping and lifting the adhesive sheet with a hook, claw, or the like; attaching a strongly adhesive tape, a suction cup or the like to the back surface of the adhesive sheet and lifting the end of the adhesive sheet; and so on. After the initial peeling front is formed by the above-described operation, the aqueous peeling liquid is supplied to the peeling front to start the water peeling, whereby the supply of the aqueous peeling liquid to the peeling front can be efficiently performed. In addition, in the above peeling method and the pressure-sensitive adhesive sheet used in the peeling method, it is desirable to simultaneously realize: performing an operation of forcibly forming an initial peeling front to make good water peelability after the start of peeling; and high water-resistant reliability without performing the operation.

In some embodiments, the above-described peeling method may preferably be performed by: after the aqueous peeling liquid is supplied to the initial peeling front (i.e., after the aqueous peeling liquid is supplied at the start of water peeling), the adhesive sheet is peeled without supplying a new aqueous peeling liquid. Alternatively, if the aqueous release liquid that has entered the interface between the adhesive sheet and the adherend following the movement of the peeling front is depleted or insufficient in the middle of the water peeling, the aqueous release liquid may be additionally supplied intermittently or continuously after the start of the water peeling. For example, in the case where the length of the peeling front increases with the progress of peeling (for example, in the case where water peeling is performed from one end of the outer edge of a disc-shaped adherend in the radial direction of the circle), or in the case where the aqueous peeling liquid is likely to remain on the surface of the adherend, it is preferable to adopt a method of additionally supplying the aqueous peeling liquid after the start of water peeling. The position to supply the aqueous stripping solution may be one or more. In the case where the aqueous stripping liquid is additionally supplied after the start of water stripping, the number of positions where the aqueous stripping liquid is supplied after the start of water stripping can be increased or decreased.

The matters disclosed in the present specification include the following.

[ 1] an adhesive sheet for semiconductor processing, which comprises an adhesive layer constituting an adhesive surface,

initial normal peel force Fd of the adhesive sheet for semiconductor processing₀Is 0.10N/20mm or more, and,

conventional peel force Fd after 15 minutes of heat treatment at 150 DEG C_aIs 1.00N/20mm or less.

[ 2] an adhesive sheet for semiconductor processing, which comprises an adhesive layer constituting an adhesive surface,

water peel force Fw_a0.30N/20mm or less, the water peeling force Fw_aMeasured by supplying water to the peeling front of the pressure-sensitive adhesive sheet peeled from the adherend after heat treatment at 150 ℃ for 15 minutes.

[ 3] an adhesive sheet for semiconductor processing, which comprises an adhesive layer constituting an adhesive surface,

the adhesive sheet for semiconductor processingInitial normal peel force Fd of₀Is 0.10N/20mm or more, and,

conventional peeling force Fd after 15 minutes of heat treatment at 200 DEG C_bIs 3.00N/20mm or less.

[ 4] an adhesive sheet for semiconductor processing, which comprises an adhesive layer constituting an adhesive surface,

water peel force Fw_b2.00N/20mm or less, the water peeling force Fw_bMeasured by supplying water to the peeling front of the pressure-sensitive adhesive sheet peeled from the adherend after heat treatment at 200 ℃ for 15 minutes.

[ 5] the adhesive sheet for semiconductor processing according to any one of [ 1] to [ 4] above, wherein the peeling force Fd is determined according to the standard peeling force after the heat treatment at 150 ℃ for 15 minutes_a[N/20mm]And a normal peeling force Fd after a heat treatment at 200 ℃ for 15 minutes_b[N/20mm]By the following formula: fd_b/Fd_aThe calculated normal peeling force ratio is 4.0 or less.

[ 6] the adhesive sheet for semiconductor processing according to any one of [ 1] to [ 5] above, wherein the peeling force Fd is determined according to the standard peeling force after the heat treatment at 150 ℃ for 15 minutes_a[N/20mm]And a normal peeling force Fd after a heat treatment at 200 ℃ for 15 minutes_b[N/20mm]By the following formula: fd_b-Fd_aThe calculated difference in the conventional peeling force was 1.50N/20mm or less.

The pressure-sensitive adhesive sheet for semiconductor processing according to any one of [ 1] to [ 6] above, which comprises a substrate supporting the pressure-sensitive adhesive layer.

[ 8 ] an adhesive sheet for semiconductor processing, which comprises an adhesive layer constituting an adhesive surface, and which satisfies the following condition A and at least one of the following conditions B to E.

(Condition A) initial Normal Peel force Fd₀Is 0.10N/20mm or more.

(Condition B) at 150 ℃ CConventional peel force Fd after line 15 minute Heat treatment_aIs 1.00N/20mm or less.

(Condition C) Water peeling Strength Fw measured by supplying water to the front edge of the adhesive sheet peeled from the adherend after heat treatment at 150 ℃ for 15 minutes_aIs 0.30N/20mm or less.

(Condition D) conventional peeling force Fd after 15-minute heat treatment at 200 ℃_bIs 3.00N/20mm or less.

(Condition E) Water peeling Strength Fw measured by supplying water to the front edge of the adhesive sheet peeled from the adherend after heat treatment at 200 ℃ for 15 minutes_bIs 2.00N/20mm or less.

The adhesive sheet according to [ 9 ] above [ 8 ], which satisfies at least the above condition A and the above condition C.

The pressure-sensitive adhesive sheet for semiconductor processing according to any one of [ 1] to [ 9 ] above, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer.

The pressure-sensitive adhesive sheet for semiconductor processing according to any one of [ 1] to [ 10 ] above, wherein the pressure-sensitive adhesive layer contains at least 1 compound A selected from the group consisting of a surfactant and a compound having a polyoxyalkylene skeleton as the heat-resistant release agent.

The pressure-sensitive adhesive sheet for semiconductor processing according to any one of [ 1] to [ 11 ] above, wherein a crosslinking agent is used in the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive sheet for semiconductor processing according to any one of [ 1] to [ 12 ] above, wherein the crosslinking agent comprises an isocyanate-based crosslinking agent.

The pressure-sensitive adhesive sheet for semiconductor processing according to any one of [ 1] to [ 12 ] above, wherein the crosslinking agent comprises an isocyanate-based crosslinking agent and an epoxy-based crosslinking agent.

A method for producing a semiconductor device using the adhesive sheet for semiconductor processing according to any one of [ 1] to [ 14 ], which comprises the steps of:

a step (1) of bonding the adhesive surface of the adhesive sheet for semiconductor processing to a circuit-forming surface side of a semiconductor wafer having the circuit-forming surface;

a step (2) of processing the semiconductor wafer to which the adhesive sheet is bonded from the side opposite to the adhesive sheet; and

and (3) peeling the adhesive sheet from the processed semiconductor wafer.

The method for manufacturing a semiconductor device according to the above [ 15 ], comprising a high-temperature exposure step of: after the step (1) and before the step (3), a high-temperature process (for example, a high-temperature process at 100 ℃ or higher, preferably 60 ℃ or higher) is performed.

The method for manufacturing a semiconductor device according to the above [ 15 ] or [ 16 ], wherein the step (3) is performed by a water stripping method.

Examples

The following description will be made of some embodiments of the present invention, but the present invention is not intended to be limited to the embodiments shown. In the following description, "part" and "%" are based on weight unless otherwise specified.

< evaluation method >

1. Initial conventional peel force Fd₀Measurement of (2)

The pressure-sensitive adhesive sheet to be measured was cut into a tape shape having a width of 20mm to prepare a test piece. The adhesive surface of the test piece was bonded to the mirror surface of a 6-inch silicon wafer (6-inch N < 100 > -100, manufactured by shin-Etsu chemical Co., Ltd.) as an adherend by a hand pressure roller under an atmosphere of 23 ℃ and 50% RH for 30 minutes to prepare a sample for evaluation.

Then, a cutter was inserted into the interface between the test piece and the adherend of the evaluation sample at 23 ℃ and 50% RH, and one end of the test piece in the longitudinal direction was peeled off from the adherend in accordance with JIS Z0237: 2009 "10.4.1 method 1: the 180 ℃ peel adhesion to the test plate "was specifically measured at a test temperature of 23 ℃ using a tensile tester (precision Universal tester" Autograph EZ-S "manufactured by Shimadzu corporation)") was measured under the conditions of a drawing speed of 300 mm/min and a peel angle of 180 degrees. The peel strength was measured so that the test piece attached to the adherend was peeled from the bottom to the top. The measurement was conducted 3 times, and the average value of them was taken as the initial ordinary peeling force Fd₀[N/20mm]。

2. Initial water peel force Fw₀Measurement of (2)

At the above initial conventional peel force Fd₀In the measurement of (3), 20. mu.L of distilled water was supplied to a position (peeling front) where the test piece started to be separated from the adherend in the middle of peeling the test piece from the adherend, and the peel strength after the supply of distilled water was measured. For the measurement, the peel strength was measured successively (i.e., 3 times), and the average value of these was defined as the initial water peel force Fw₀[N/20mm]。

3. Measurement of conventional peeling force after heating

(conventional Peel force after heating at 150 ℃ Fd_a)

The initial conventional peel force Fd as described above was applied at 150 ℃ for 15 minutes₀The evaluation sample prepared in the same manner as in the measurement was heated. After heating, the mixture was left to cool for 30 minutes in a normal temperature (25 ℃ C.) environment. After standing to cool, the composition is cured to an initial conventional peel force Fd as described above₀The peel strength was measured in the same manner as in the above measurement. The average value of the 3 measurements was taken as the conventional peel force Fd after heating at 150 deg.C_a[N/20mm]。

(conventional Peel force after heating at 200 ℃ Fd_b)

Except that the heating condition was changed to 200 ℃ for 15 minutes, the conventional peeling force Fd after heating at 150 ℃ as described above was used_aIn the same manner as in the measurement, the conventional peeling force Fd after heating at 200 ℃ was measured_b[N/20mm]。

4. Measurement of Water peeling force after heating

(Water peeling force Fw after heating at 150 ℃ C.)_a)

Normal peel force Fd after heating at 150 ℃ as described above_aIn the measurement of (3), the test piece is separated from the adherend in the course of the separation of the test piece from the adherend, and the separation is started from the adherend to the test piece20 μ L of distilled water was supplied to the position where the adherend was separated (peeling front), and the peel strength after the supply of distilled water was measured. For the measurement, the peel strength was measured successively (i.e., 3 times), and the average value thereof was defined as the water peel force Fw after heating at 150 ℃_a[N/20mm]。

(Water peeling force Fw after heating at 200 ℃_b)

The heating conditions were changed to 200 ℃ for 15 minutes, and the water-peeling force Fw after heating at 150 ℃ was adjusted_aIn the same manner as in the measurement, the water peeling force Fw after heating at 200 ℃ was measured_b[N/20mm]。

< example 1 >

(preparation of adhesive composition)

A monomer composition was prepared by mixing 100 parts of n-Butyl Acrylate (BA) and 3 parts of acrylic acid as monomer raw materials, 0.2 part of 2, 2' -Azobisisobutyronitrile (AIBN) as a polymerization initiator, and toluene as a polymerization solvent.

The monomer composition was charged into a polymerization experimental apparatus equipped with a removable lid, a separatory funnel, a thermometer, a nitrogen inlet, a Libixi condenser, a vacuum seal, a stirring bar, and a stirring blade in a 1L round-bottom removable flask, and nitrogen substitution was performed at room temperature for 2 hours while stirring. Then, the mixture was kept at 60 ℃ for 5 hours under a nitrogen stream with stirring to carry out polymerization, thereby obtaining a solution of polymer P1 (Mw: about 100 ten thousand). The Tg, calculated from the Fox equation on the basis of the composition of the above-mentioned monomer starting materials, was-52.3 ℃.

The solution of the polymer P1 was cooled to room temperature, and 2.0 parts of an isocyanate-based crosslinking agent (trimethylolpropane/tolylene diisocyanate trimer adduct, manufactured by Tosoh Corporation, trade name "Coronate L", solid content concentration 75 wt%) was added to the solution in terms of solid content relative to 1100 parts of the polymer P in the solution, and 0.7 parts of an epoxy-based crosslinking agent (manufactured by mitsubishi gas chemical Corporation, trade name "TETRAD C") was added and mixed to prepare an adhesive composition C1.

(preparation and evaluation of pressure-sensitive adhesive sheet)

A pressure-sensitive adhesive composition C1 was applied to a release surface of a polyethylene terephthalate (PET) film (MRF 38, Mitsubishi resin Co., Ltd.) having a thickness of 38 μm, which was a release surface treated with silicone, on one surface thereof, and the release surface was dried at 140 ℃ for 2 minutes to form a pressure-sensitive adhesive layer having a thickness of 20 μm. The pressure-sensitive adhesive layer was bonded to an easy-adhesion surface of an easy-adhesion treated PET film (thickness: 50 μm) as a substrate, and then aged at 50 ℃ for 2 days to obtain a pressure-sensitive adhesive sheet (single-sided pressure-sensitive adhesive sheet with substrate) according to the present example.

The peel force of the obtained adhesive sheet was measured by the above-mentioned method, and the conventional peel force ratio (Fd) was calculated from the measured value_b/Fd_a) And conventional poor peel force (Fd)_b-Fd_a). The results are shown in Table 1.

< example 2 >

To the solution of the polymer P1, 0.1 part of a nonionic surfactant a1 (polyoxyethylene sorbitan monolaurate, a sorbitan fatty acid ester manufactured by kao corporation, trade name "Rheodol TW-L120", the number of moles of ethylene oxide added was 20, and HLB was 16.7) which is a compound a dissolved in ethyl acetate without phase separation in the test I was further added, relative to 1100 parts of the polymer P in the solution. In addition to the above aspects, an adhesive composition C2 was prepared in the same manner as the preparation of the adhesive composition C1.

The nonionic surfactant a1 was used in the form of an ethyl acetate solution and in such an amount as described above based on the solid content. The same applies to the preparation of adhesive compositions C3 to C5.

A pressure-sensitive adhesive sheet according to the present example was obtained in the same manner as in example 1, except that the pressure-sensitive adhesive composition C2 was used.

The obtained pressure-sensitive adhesive sheet was evaluated in the same manner as in example 1. The results are shown in Table 1.

< examples 3 to 5 >

Adhesive compositions C3 to C5 according to examples 3 to 5 were prepared in the same manner as in the preparation of adhesive composition C2, except that the amount of the nonionic surfactant a1 added to 100 parts of the polymer P1 was changed as shown in table 1. Pressure-sensitive adhesive sheets according to examples 3 to 5 were obtained in the same manner as in example 1, except that the pressure-sensitive adhesive compositions C3 to C5 were used. The obtained pressure-sensitive adhesive sheet was evaluated in the same manner as in example 1. The results are shown in Table 1.

[ Table 1]

TABLE 1

As shown in table 1, the pressure-sensitive adhesive sheets of examples 2 to 5 had significantly lower peel strength after high-temperature exposure than the pressure-sensitive adhesive sheet of example 1, and had an excellent balance between adhesion to an adherend and bonding reliability during processing. Examples 3 to 5 are particularly excellent results.

Specific examples of the present invention have been described above in detail, but these are merely examples and do not limit the claims. The techniques recited in the claims include various modifications and changes to the specific examples illustrated above.

Claims

1. A pressure-sensitive adhesive sheet for semiconductor processing, which comprises a pressure-sensitive adhesive layer constituting a pressure-sensitive adhesive surface,

2. A pressure-sensitive adhesive sheet for semiconductor processing, which comprises a pressure-sensitive adhesive layer constituting a pressure-sensitive adhesive surface,

water peel force Fw_a0.30N/20mm or less, the water peeling force Fw_aIs applied to an adherend of the pressure-sensitive adhesive sheet after heat treatment at 150 ℃ for 15 minutesThe peeling front of the peeling was measured by supplying water.

3. A pressure-sensitive adhesive sheet for semiconductor processing, which comprises a pressure-sensitive adhesive layer constituting a pressure-sensitive adhesive surface,

4. A pressure-sensitive adhesive sheet for semiconductor processing, which comprises a pressure-sensitive adhesive layer constituting a pressure-sensitive adhesive surface,

5. The adhesive sheet for semiconductor processing according to any one of claims 1 to 4, wherein the peeling force Fd is determined according to a standard peeling force after a heat treatment at 150 ℃ for 15 minutes_a[N/20mm]And a normal peeling force Fd after a heat treatment at 200 ℃ for 15 minutes_b[N/20mm]By the following formula: fd_b/Fd_aThe calculated normal peeling force ratio is 4.0 or less.

6. The adhesive sheet for semiconductor processing according to any one of claims 1 to 5, wherein the peeling force Fd is determined according to a standard peeling force after a heat treatment at 150 ℃ for 15 minutes_a[N/20mm]And a normal peeling force Fd after a heat treatment at 200 ℃ for 15 minutes_b[N/20mm]By the following formula: fd_b-Fd_aThe calculated difference in the conventional peeling force was 1.50N/20mm or less.

7. The adhesive sheet for semiconductor processing according to any one of claims 1 to 6, which comprises a substrate supporting the adhesive layer.