KR20230154826A - Manufacturing method of adhesive sheet for semiconductor processing and semiconductor device - Google Patents

Abstract

An adhesive sheet for semiconductor processing, which has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order, and has a static contact angle of water at 23° C. with respect to the surface coat layer of 85° or more, and the adhesive sheet for semiconductor processing It relates to a manufacturing method of a semiconductor device to be used.

Description

Manufacturing method of adhesive sheet for semiconductor processing and semiconductor device

The present invention relates to a method of manufacturing an adhesive sheet for semiconductor processing and a semiconductor device.

As information terminal devices are rapidly becoming thinner, more compact, and more functional, there is a demand for semiconductor devices mounted on these devices to be thinner and more dense.

As a method of reducing the thickness of a semiconductor device, a method of grinding the back side of a semiconductor wafer used in the semiconductor device has been implemented. Back grinding of a semiconductor wafer is performed by attaching an adhesive sheet for back grinding (hereinafter also referred to as “back grind sheet”) to the surface of the semiconductor wafer and protecting the surface of the semiconductor wafer with the sheet. . The back grind sheet is peeled and removed from the surface of the semiconductor wafer after back grinding.

Recently, pre-dicing methods, stealth pre-dicing methods, etc. have been used as grinding and segmentation methods to reduce the thickness of semiconductor chips while suppressing damage to them. The line dicing method is a method of forming a groove of a predetermined depth on the surface of a semiconductor wafer with a dicing blade or the like, and then grinding the semiconductor wafer from the back side to the groove to separate it into semiconductor chips. In addition, the stealth line dicing method forms a modified region inside a semiconductor wafer by irradiation of laser light, then grinds the semiconductor wafer from the back side, and divides the modified region into pieces by using the modified region as a starting point for division. This is how to do it. In these methods as well, a back grind sheet is used to protect the surface of the semiconductor wafer.

Along with the development of these thinning process technologies, back grind sheets are also required to have a function for thinning semiconductor chips with high yield, and various studies are being conducted.

Patent Document 1 discloses an adhesive sheet for semiconductor wafer surface protection applicable to a line dicing method or a stealth line dicing method, comprising a base film, an intermediate layer formed on at least one side of the base film and made of an adhesive, and the base material of the intermediate layer. An adhesive sheet for semiconductor wafer surface protection is disclosed, which is an adhesive sheet having an outermost adhesive layer formed on the outermost layer on the opposite side from the film, wherein the intermediate layer is formed of a material that is hardened by a curing treatment after forming the adhesive sheet. there is.

Japanese Patent Publication No. 2015-56446

According to the adhesive sheet for semiconductor wafer surface protection of Patent Document 1, after the semiconductor wafer is divided into chips, kerf shift, which causes the original chip gap to collapse, can be suppressed, and contamination by grinding debris of the semiconductor wafer can be suppressed. It is said that it can prevent glue from remaining on the chip when the surface protection tape is peeled off.

However, when performing back grinding, the back grind sheet attached to the semiconductor wafer is fixed on the side opposite to the surface attached to the semiconductor wafer (hereinafter also referred to as “back surface”) by a support device such as a chuck table. Then, the back side of the semiconductor wafer fixed on the table of the support device through the back grind sheet is ground while cooling water to remove heat from grinding and grinding debris is supplied to the grinding surface.

When performing back grinding, if grinding debris exists between the back grind sheet and the table of the support device, shock when fixing the semiconductor wafer to the table starting from the part where the grinding debris exists, pressure during back grinding, and Cracks may occur in semiconductor wafers or semiconductor chips due to vibration or the like. Since grinding debris adheres to the back surface of the back grind sheet while contained in the cooling water, in order to suppress the occurrence of cracks, it is necessary to reduce the amount of grinding waste adhering to the back surface of the back grind sheet.

The adhesive sheet for semiconductor wafer surface protection of Patent Document 1 could not sufficiently comply with the request to reduce the amount of grinding debris adhering to the back surface of the back grind sheet.

The present invention has been made in view of the above circumstances, and its purpose is to provide an adhesive sheet for semiconductor processing with a reduced amount of adhesion of grinding debris, and a method for manufacturing a semiconductor device using the adhesive sheet for semiconductor processing.

As a result of intensive study, the present inventors have found that the above problems can be solved by an adhesive sheet for semiconductor processing having a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order, the static contact angle of water at 23°C being within a specific range. By finding this out, the following invention was completed.

That is, the present invention relates to the following [1] to [11].

[1] It has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order,

An adhesive sheet for semiconductor processing, wherein the static contact angle of water at 23°C with respect to the surface coat layer is 85° or more.

[2] The adhesive sheet for semiconductor processing according to [1] above, wherein the surface coat layer is an organic layer containing a resin component.

[3] The adhesive sheet for semiconductor processing according to [2] above, wherein the resin component is a thermoplastic resin.

[4] The adhesive sheet for semiconductor processing according to [2] or [3] above, wherein the resin component has a heteroatom content of 7% by mass or less.

[5] The adhesive sheet for semiconductor processing according to any one of [2] to [4] above, wherein the resin component dissolves 1% by mass or more in toluene at 23°C.

[6] The adhesive sheet for semiconductor processing according to any one of [1] to [5] above, wherein the static contact angle of water at 23°C with respect to the surface coat layer is 90° or more.

[7] The adhesive sheet for semiconductor processing according to any one of [1] to [6], wherein the surface coating layer has a thickness of 0.05 to 10 μm.

[8] The adhesive sheet for semiconductor processing according to any one of [1] to [7] above, wherein the buffer layer is formed from a composition for forming a buffer layer containing urethane (meth)acrylate.

[9] The adhesive sheet for semiconductor processing according to any one of [1] to [8] above, which is used for backside grinding of a semiconductor wafer.

[10] A process of attaching the adhesive sheet for semiconductor processing according to any one of [1] to [9] above to the surface of a semiconductor wafer using the adhesive layer as an attachment surface;

A method of manufacturing a semiconductor device, comprising the step of grinding the back surface of the semiconductor wafer while the surface coat layer side of the adhesive sheet for semiconductor processing attached to the semiconductor wafer is fixed by a support device.

[11] A process for forming a line to be divided, which is a process a for forming a groove on the surface of a semiconductor wafer, or a process b for forming a modified area inside the semiconductor wafer from the front or back surface of the semiconductor wafer;

After the step a, or before or after the step b, the adhesive sheet for semiconductor processing according to any one of [1] to [9] above is attached to the surface of the semiconductor wafer, using the adhesive layer as a sticking surface. The sheet sticking process,

With the surface coat layer side of the adhesive sheet for semiconductor processing attached to the semiconductor wafer being fixed by a support device, the back side of the semiconductor wafer is ground and divided into a plurality of semiconductor chips using the groove or modified area as a starting point. The method for manufacturing a semiconductor device according to [10] above, including a grinding and segmentation process.

According to the present invention, an adhesive sheet for semiconductor processing with a reduced amount of adhesion of grinding debris, and a method for manufacturing a semiconductor device using the adhesive sheet for semiconductor processing can be provided.

In this specification, the lower limit and upper limit values described step by step for the preferred numerical range can be independently combined. For example, from the description “preferably 10 to 90, more preferably 30 to 60”, “preferable lower limit value (10)” and “more preferred upper limit value (60)” are combined to “10 to 60”. You may.

In this specification, for example, “(meth)acrylic acid” refers to both “acrylic acid” and “methacrylic acid”, and other similar terms are also the same.

In this specification, “energy ray” means an electromagnetic wave or a charged particle beam that has energy quantum, and examples thereof include ultraviolet rays, radiation, and electron beams. Ultraviolet rays can be irradiated, for example, by using an electrodeless lamp, high-pressure mercury lamp, metal halide lamp, UV-LED, etc. as an ultraviolet ray source. Electron beams generated by an electron beam accelerator or the like can be irradiated.

In this specification, “energy ray polymerizability” means the property of polymerizing by irradiating energy rays. In addition, “energy ray curability” refers to the property of being hardened by irradiating an energy ray, and “non-energy ray curability” refers to the property of not having energy ray curability.

In this specification, the “surface” of a semiconductor wafer refers to the surface on which circuits are formed, and the “back surface” refers to the surface on which circuits are not formed.

The mechanism of action described in this specification is a guess and does not limit the mechanism showing the effect of the adhesive sheet for semiconductor processing of the present invention.

[Adhesive sheet for semiconductor processing]

The adhesive sheet for semiconductor processing (hereinafter also referred to as “adhesive sheet”) of the present embodiment has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order, and the water at 23°C with respect to the surface coat layer It is an adhesive sheet for semiconductor processing with a static contact angle of 85° or more.

The adhesive sheet of this embodiment is affixed to the surface of a work-in semiconductor device and is used to perform predetermined processing on the semiconductor device while protecting the surface. After predetermined processing is performed on the work, the adhesive sheet of this embodiment is peeled and removed from the semiconductor device.

In addition, in this embodiment, “semiconductor device” refers to the overall device that can function by utilizing semiconductor characteristics, for example, a semiconductor wafer, a semiconductor chip, an electronic component including the semiconductor chip, and the electronic component. Electronic devices including, etc. may be mentioned. Among these, the adhesive sheet of this embodiment is suitable for processing semiconductor wafers.

The adhesive sheet of this embodiment may or may not have layers other than the surface coat layer, buffer layer, base material, and adhesive layer. Layers other than the base material and the adhesive layer include, for example, an intermediate layer formed between the base material and the adhesive layer, a release sheet formed on the side of the adhesive layer opposite to the base material, and the like.

Hereinafter, each member constituting the adhesive sheet of this embodiment will be described in order.

<Surface coat layer>

The surface coat layer is a layer formed on the side opposite to the base material of the buffer layer and is fixed by a support device when processing a semiconductor device.

(contact angle)

The surface coat layer has a static contact angle of water at 23°C (hereinafter simply referred to as “water contact angle”) of 85° or more, and has the property that water including grinding debris is difficult to adhere to. Therefore, the adhesive sheet of the present embodiment has a reduced amount of grinding debris adhering to the back surface, and can suppress damage to the work caused by grinding debris adhering to the back surface.

The water contact angle of the surface coat layer is preferably 90° or higher, more preferably 93° or higher, and even more preferably 96° or higher from the viewpoint of further reducing the amount of adhesion of grinding chips. The upper limit of the water contact angle of the surface coat layer is not particularly limited, but may be, for example, 150° or less or 100° or less from the viewpoint of ease of manufacture.

In addition, the water contact angle of the surface coat layer is a value measured based on JIS R 3257:1999, and can be specifically measured by the method described in the Examples.

The surface coat layer is not particularly limited as long as it has a water contact angle of 85° or more, and may be an inorganic layer or an organic layer, but is preferably an organic layer from the viewpoint of productivity and handleability of the adhesive sheet.

The organic layer is preferably a layer containing a resin component, and the resin component contained in the organic layer is preferably a thermoplastic resin and more preferably a polyolefin resin from the viewpoint of easy adjustment of the water contact angle to 85° or more.

(Hetero atom content of resin components)

The content of hetero atoms in the resin component contained in the organic layer is not particularly limited, but is preferably 7% by mass or less, more preferably 0.2 to 4% by mass, and even more preferably 0.5 to 1% by mass.

If the heteroatom content in the resin component is below the above upper limit, the amount of grinding debris adhesion tends to be further reduced. Moreover, if the heteroatom content in the resin component is more than the above lower limit, the solvent solubility of the resin component improves, and the formation of a surface coat layer by application of the resin component tends to become easy.

In addition, in this specification, “hetero atom” means all atoms other than carbon atoms and hydrogen atoms.

(Solvent solubility of resin components)

The resin component contained in the organic layer preferably has solubility in an organic solvent from the viewpoint of facilitating the formation of a surface coat layer by application. Specifically, at 23°C, the resin component is preferably dissolved in toluene in an amount of 1% by mass or more, more preferably 5% by mass or more, and even more preferably 8% by mass or more.

Hereinafter, preferred embodiments of the surface coat layer containing polyolefin resin as the resin component will be described in detail.

(polyolefin resin)

The polyolefin-based resin contained in the surface coat layer is a resin formed by polymerizing a monomer containing at least olefin.

Here, the “polyolefin-based resin” in this embodiment is a resin formed by homopolymerizing olefin, or a resin formed by copolymerizing olefin with a monomer other than olefin, and contains 50% by mass or more of structural units derived from olefin. Which of the resins does it mean?

In addition, “olefin” in this embodiment means an unsaturated hydrocarbon having an ethylenically unsaturated bond, and compounds containing heteroatoms are not included in “olefin” in this embodiment.

In addition, the “ethylenically unsaturated bond” in this embodiment means a carbon-carbon double bond capable of addition reaction, and does not include a double bond in an aromatic ring.

In addition, in the following description, a group containing an ethylenically unsaturated bond may simply be referred to as an “unsaturated group.”

Polyolefin resin may be used individually by 1 type, or may use 2 or more types together.

The content of the structural unit derived from olefin in the polyolefin resin is not particularly limited, but is preferably 70% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more. If the content of the structural unit derived from olefin in the polyolefin resin is more than the above lower limit, the amount of grinding debris adhesion tends to be further reduced.

In addition, the content of the structural unit derived from olefin in the polyolefin resin may be 100% by mass, but is preferably 99.5% by mass or less, and more preferably 99% by mass or less. If the content of the structural unit derived from olefin in the polyolefin resin is below the above upper limit, structural units derived from monomers other than olefin can be contained for the purpose of improving solvent solubility, etc., and formation of a surface coat layer by application. This tends to become easier.

Examples of olefins constituting the polyolefin resin include chain olefins, cyclic olefins, and aromatic vinyl compounds.

The olefins constituting the polyolefin-based resin may be used individually or in combination of two or more types.

Examples of chain olefins include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 2-methyl-1-propene. , chain monoolefins such as 3-methyl-1-pentene, 4-methyl-1-pentene, and 5-methyl-1-hexene; Chain non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene; Chain-type conjugated dienes such as 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-phenyl-1,3-butadiene, and 1,3-hexadiene ; etc. can be mentioned. Among these, chain olefins having 2 to 6 carbon atoms are preferable, and ethylene and propylene are more preferable.

Examples of the cyclic olefin include cyclic monoolefins such as cyclobutene, cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, cycloheptene, and cyclooctene; Cyclic diolefins such as cyclohexadiene, methylcyclohexadiene, cyclooctadiene, methylcyclooctadiene, and phenylcyclooctadiene; Norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, tetracyclo[7.4.0.110,13.02,7]trideca-2,4,6,11-tetra Polycyclic olefins such as N; etc. can be mentioned. Among these, tetracyclododecene is preferable from the viewpoint of improving solvent solubility and facilitating the formation of a surface coat layer by application.

Examples of aromatic vinyl compounds include styrene, o-methylstyrene, m-methylstyrene, and p-methylstyrene.

Examples of monomers other than olefins that may be copolymerized with olefins include monomers having an oxygen atom and an ethylenically unsaturated bond, monomers having a nitrogen atom and an ethylenically unsaturated bond, and the like.

Monomers other than olefin may be used individually by 1 type, or may be used in combination of 2 or more types.

Examples of the monomer having an oxygen atom and an ethylenically unsaturated bond include acid anhydrides such as maleic anhydride, methyl maleic anhydride, dimethyl maleic anhydride, phenyl maleic anhydride, and diphenyl maleic anhydride; Maleic acids such as maleic acid, methylmaleic acid, dimethyl maleate, diethyl maleate, dibutyl maleate, and monomethyl maleate; Methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cycloalkyl (meth)acrylate with 3 to 20 carbon atoms in the cycloalkyl group, benzyl ( (meth)acrylic acid and (meth)acrylic acid ester, such as meth)acrylate and isobornyl (meth)acrylate; Vinyl ester compounds such as vinyl acetate and vinyl propionate; etc. can be mentioned. Among these, from the viewpoint of improving solvent solubility and facilitating the formation of a surface coating layer by application, acid anhydrides and vinyl ester compounds are preferable, maleic anhydride and vinyl acetate are more preferable, and maleic anhydride is still more preferable. .

Examples of monomers having a nitrogen atom and an ethylenically unsaturated bond include maleimide compounds, derivatives thereof, and nitrile-based monomers.

Examples of the maleimide compound and its derivatives include maleimide; N-alkyl substituted maleimide such as N-methylmaleimide and N-ethylmaleimide; N-aryl substituted maleimides such as N-phenylmaleimide; etc. can be mentioned. Examples of nitrile-based monomers include acrylonitrile and methacrylonitrile.

Among the above structural units, the polyolefin resin is a structural unit derived from a chain olefin having 2 to 6 carbon atoms from the viewpoint of further reducing the amount of adhesion of grinding chips (hereinafter also referred to as “chain olefin structural unit (A)”). It is preferable to contain, and it is more preferable to contain at least one type selected from the group consisting of structural units derived from ethylene and structural units derived from propylene.

The polyolefin resin is derived from a monomer having an oxygen atom and an ethylenically unsaturated bond together with the chain olefin structural unit (A) from the viewpoint of improving solvent solubility and facilitating the formation of a surface coat layer by application. It is preferable to contain the structural unit (hereinafter also referred to as “structural unit (B) containing an oxygen atom”).

When the polyolefin-based resin contains a chain olefin-based structural unit (A) and a structural unit (B) containing an oxygen atom, the content of the chain olefin-based structural unit (A) in the polyolefin-based resin is particularly limited. However, it is preferably 80 to 99.5 mass%, more preferably 90 to 99 mass%, and even more preferably 95 to 98.8 mass%.

When the polyolefin-based resin contains a chain olefin-based structural unit (A) and a structural unit (B) containing an oxygen atom, the content of the structural unit (B) containing an oxygen atom in the polyolefin-based resin is particularly Although it is not limited, it is preferably 0.5 to 20 mass%, more preferably 1 to 10 mass%, and even more preferably 1.2 to 5 mass%.

If the content of the chain olefin-based structural unit (A) and the structural unit (B) containing an oxygen atom is within the above range, good solvent solubility is obtained and the amount of grinding debris adhesion tends to be further reduced.

In addition, from the viewpoint of improving solvent solubility and facilitating the formation of a surface coat layer by application, the polyolefin-based resin, together with the chain olefin-based structural unit (A), contains a structural unit derived from cyclic olefin (hereinafter referred to as , also referred to as “cyclic olefin-based structural unit (C)”), is preferably contained.

When the polyolefin-based resin contains a chain olefin-based structural unit (A) and a cyclic olefin-based structural unit (C), the content of the chain olefin-based structural unit (A) in the polyolefin-based resin is not particularly limited. However, it is preferably 10 to 90 mass%, more preferably 20 to 70 mass%, and even more preferably 25 to 50 mass%.

When the polyolefin-based resin contains a chain olefin-based structural unit (A) and a cyclic olefin-based structural unit (C), the content of the cyclic olefin-based structural unit (C) in the polyolefin-based resin is not particularly limited. However, it is preferably 10 to 90 mass%, more preferably 30 to 80 mass%, and even more preferably 50 to 75 mass%.

If the content of the chain olefin-based structural unit (A) and the cyclic olefin-based structural unit (C) is within the above range, good solvent solubility is obtained and the amount of grinding debris adhesion tends to be further reduced.

Examples of the polyolefin resin include homopolymers such as polyethylene, polypropylene, and polybutadiene; Ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, ethylene-(meth)acrylate copolymer, ethylene-tetracyclododecene copolymer, propylene-butene copolymer. Binary copolymers such as polymers, propylene-maleic anhydride copolymer, propylene-vinyl acetate copolymer, propylene-(meth)acrylate copolymer, and propylene-tetracyclododecene copolymer; Ethylene-maleic anhydride-vinyl acetate copolymer, ethylene-maleic anhydride-(meth)acrylate copolymer, ethylene-vinyl acetate-(meth)acrylate copolymer, propylene-maleic anhydride-vinyl acetate copolymer, propylene -Maleic anhydride-(meth)acrylate copolymer, propylene-vinyl acetate-(meth)acrylate copolymer, ethylene-propylene-maleic anhydride copolymer, ethylene-propylene-vinyl acetate copolymer, ethylene-propylene-( Meth)acrylate copolymer, ethylene-butene-maleic anhydride copolymer, ethylene-butene-vinyl acetate copolymer, ethylene-butene-(meth)acrylate copolymer, propylene-butene-maleic anhydride copolymer, propylene- Multipolymers such as butene-vinyl acetate copolymer and propylene-butene-(meth)acrylate copolymer; etc. can be mentioned.

Among these, ethylene-vinyl acetate copolymer, ethylene-tetracyclododecene copolymer, ethylene-vinyl acetate copolymer, ethylene-tetracyclododecene copolymer, from the viewpoint of further reducing the amount of adhesion of grinding chips and improving solvent solubility to facilitate formation of a surface coat layer by application. Butene-maleic anhydride copolymer is preferred, and ethylene-butene-maleic anhydride copolymer is more preferred.

When the organic layer contains a polyolefin-based resin as a resin component, the organic layer may contain a resin other than the polyolefin-based resin.

The content of the polyolefin resin in the resin component is not particularly limited, but is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and further preferably 98% by mass, from the viewpoint of further reducing the amount of adhesion of grinding chips. It is ~100% by mass.

(Other ingredients)

The organic layer may contain components other than the resin component within a range that does not impair the effect of the present invention. Other components include, for example, additives such as antistatic agents, antioxidants, softeners, fillers, rust preventives, pigments, and dyes; etc. can be mentioned.

The content of the resin component relative to the total amount of the organic layer is not particularly limited, but is preferably 90 to 100% by mass, more preferably 95 to 100% by mass, and still more preferably 98 to 98% by mass, from the viewpoint of further reducing the amount of adhesion of grinding debris. It is 100% by mass.

The thickness of the surface coat layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.2 to 7 μm, and still more preferably 1 to 4 μm.

If the thickness of the surface coat layer is more than the above lower limit, uniform layer formation becomes possible and the amount of grinding debris adhesion tends to be sufficiently reduced. Moreover, if the thickness of the surface coat layer is below the above upper limit, the effect of the buffer layer of absorbing irregularities such as foreign matter on the chuck table tends to be easily obtained.

＜Buffer layer＞

The buffer layer is a layer formed between the base material and the surface coating layer, and is a layer that absorbs vibration and shock generated during back side grinding and prevents cracks from occurring in the workpiece. Furthermore, by forming a buffer layer, it is possible to absorb irregularities such as foreign matter existing on the table of the support device and improve the retention of the adhesive sheet by the support device.

(Composition for forming a buffer layer)

The buffer layer can be formed from a composition for forming a buffer layer.

From the viewpoint of obtaining appropriate physical properties for the buffer layer, the buffer layer is preferably a layer obtained by energy-ray curing a composition for forming a buffer layer containing an energy-ray polymerizable compound.

The composition for forming a buffer layer preferably contains urethane (meth)acrylate (a1) as an energy ray polymerizable compound. When the composition for forming a buffer layer contains urethane (meth)acrylate (a1), the storage modulus of the buffer layer tends to be adjusted to a good range.

Additionally, from the same viewpoint, the composition for forming a buffer layer includes, in addition to urethane (meth)acrylate (a1), a polymerizable compound (a2) having an alicyclic or heterocyclic group having 6 to 20 ring atoms and a functional group. It is more preferable to contain at least one selected from the group consisting of polymerizable compounds (a3), and in addition to urethane (meth)acrylate (a1), an alicyclic group or heterocyclic group having 6 to 20 ring atoms is added. It is more preferable to contain a polymerizable compound (a2) having a polymerizable compound (a2) and a polymerizable compound (a3) having a functional group.

[Urethane (meth)acrylate (a1)]

Urethane (meth)acrylate (a1) is a compound having a (meth)acryloyl group and a urethane bond, and has the property of polymerizing by energy ray irradiation.

Urethane (meth)acrylate (a1) may be used individually or in combination of two or more types.

The mass average molecular weight (Mw) of urethane (meth)acrylate (a1) is not particularly limited, but is preferably 1,000 to 100,000, more preferably 2,000 to 60,000, and still more preferably 3,000 to 20,000.

In addition, in this embodiment, the mass average molecular weight (Mw) means the standard polystyrene conversion value measured by the gel permeation chromatography (GPC) method, and specifically, the value measured by the method described in the Examples. am.

The number of (meth)acryloyl groups that urethane (meth)acrylate (a1) has in one molecule is not particularly limited, but is preferably 1 to 4, more preferably 1 to 3, and even more preferably 1. There are one or two.

Urethane (meth)acrylate (a1) can be obtained, for example, by reacting (meth)acrylate having a hydroxy group with a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound and a polyhydric isocyanate compound.

The polyol compound is not particularly limited as long as it is a compound having two or more hydroxy groups.

Specific examples of polyol compounds include alkylene diol, polyether type polyol, polyester type polyol, and polycarbonate type polyol. Among these, polyester type polyol is preferable.

The polyol compound may be any of a bifunctional diol, a trifunctional triol, or a tetrafunctional or higher functional polyol, but a bifunctional diol is preferable and a polyester type diol is more preferable.

A polyol compound may be used individually by 1 type, or may use 2 or more types together.

Examples of the polyvalent isocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; Alicyclic products such as isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, ω,ω'-diisocyanate and dimethylcyclohexane. Diisocyanates; aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, and naphthalene-1,5-diisocyanate; etc. can be mentioned. Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferable.

A polyhydric isocyanate compound may be used individually by 1 type, or may use 2 or more types together.

The (meth)acrylate having a hydroxy group to be reacted with the terminal isocyanate urethane prepolymer is not particularly limited as long as it is a compound having a hydroxy group and a (meth)acryloyl group in at least one molecule.

Examples of (meth)acrylates having a hydroxy group include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 4 -Hydroxycyclohexyl (meth)acrylate, 5-hydroxycyclooctyl (meth)acrylate, 2-hydroxy-3-phenyloxypropyl (meth)acrylate, pentaerythritol tri(meth)acrylate, polyethylene Hydroxyalkyl (meth)acrylates such as glycol mono(meth)acrylate and polypropylene glycol mono(meth)acrylate; Hydroxyl group-containing (meth)acrylamide such as N-methylol (meth)acrylamide; Reactants obtained by reacting vinyl alcohol, vinyl phenol, and diglycidyl ester of bisphenol A with (meth)acrylic acid; etc. can be mentioned. Among these, hydroxyalkyl (meth)acrylate is preferable and 2-hydroxyethyl (meth)acrylate is more preferable.

(meth)acrylates having a hydroxy group may be used individually by one type, or may be used in combination of two or more types.

The conditions for reacting the terminal isocyanate urethane prepolymer with the (meth)acrylate having a hydroxy group are not particularly limited, but for example, 1 to 4 hours at 60 to 100°C in the presence of solvents, catalysts, etc. added as necessary. This can be done under reaction conditions.

The content of urethane (meth)acrylate (a1) in the composition for forming a buffer layer is not particularly limited, but is preferably 10 to 70% by mass relative to the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer. , more preferably 20 to 60 mass%, and even more preferably 30 to 50 mass%.

In addition, in this embodiment, the active ingredient of the composition for forming a buffer layer means a component contained in the composition for forming a buffer layer excluding components such as organic solvents removed in the process of forming the buffer layer.

[Polymerizable compound (a2) having an alicyclic or heterocyclic group having 6 to 20 ring atoms]

The composition for forming a buffer layer contains a polymerizable compound (a2) having an alicyclic or heterocyclic group having 6 to 20 ring atoms (hereinafter also referred to as “polymerizable compound (a2) having an alicyclic or heterocyclic group”). By doing so, the film forming properties of the composition for forming a buffer layer tend to improve.

In addition, the number of ring-forming atoms refers to the number of atoms constituting the ring itself of a compound with a structure in which atoms are bonded in a ring, and refers to the number of atoms that do not constitute a ring (for example, a hydrogen atom bonded to an atom that constitutes a ring). , and when the ring is substituted by a substituent, the atoms included in the substituent are not included in the number of ring forming atoms. Examples of atoms forming the ring structure of the heterocyclic group include carbon atoms, nitrogen atoms, oxygen atoms, and sulfur atoms.

The polymerizable compound (a2) having an alicyclic group or a heterocyclic group may be used individually or in combination of two or more types.

The polymerizable compound (a2) having an alicyclic group or a heterocyclic group is preferably a compound having a (meth)acryloyl group.

The number of (meth)acryloyl groups that the polymerizable compound (a2) having an alicyclic group or a heterocyclic group has in one molecule is not particularly limited, but is preferably one or more, more preferably one or two, and further. Preferably one.

The number of ring forming atoms of the alicyclic group or heterocyclic group of the polymerizable compound (a2) having an alicyclic group or a heterocyclic group is 6 to 20, preferably 6 to 18, more preferably 6 to 16, even more preferably. The average number is 7 to 12.

Examples of the polymerizable compound (a2) having an alicyclic group or a heterocyclic group include isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and dicyclophene. Alicyclic group-containing (meth)acrylates such as thenyloxy (meth)acrylate, cyclohexyl (meth)acrylate, and adamantane (meth)acrylate; Heterocyclic group-containing (meth)acrylates such as tetrahydrofurfuryl (meth)acrylate and morpholine (meth)acrylate; etc. can be mentioned. Among these, alicyclic group-containing (meth)acrylate is preferable, and isobornyl (meth)acrylate is more preferable.

The content of the polymerizable compound (a2) having an alicyclic group or a heterocyclic group in the composition for forming a buffer layer is not particularly limited, but is preferably 10 to 70% based on the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer. It is % by mass, more preferably 20 to 60 % by mass, and even more preferably 30 to 50 % by mass.

[Polymerizable compound having a functional group (a3)]

When the composition for forming a buffer layer contains a polymerizable compound (a3) having a functional group, the viscosity of the composition for forming a buffer layer tends to be adjusted to an appropriate range.

The polymerizable compound (a3) having a functional group may be used individually or in combination of two or more types.

Examples of the functional group possessed by the polymerizable compound (a3) having a functional group include a hydroxyl group, an epoxy group, an amide group, and an amino group.

The number of functional groups in one molecule of the polymerizable compound (a3) having a functional group is 1 or more, preferably 1 to 3, more preferably 1 or 2, and still more preferably 1.

The polymerizable compound (a3) having a functional group is preferably a compound having a (meth)acryloyl group together with the functional group.

The number of (meth)acryloyl groups that the polymerizable compound (a3) having a functional group has in one molecule is not particularly limited, but is preferably 1 or more, more preferably 1 or 2, and even more preferably 1. It's a dog.

Examples of the polymerizable compound (a3) having a functional group include a hydroxyl group-containing polymerizable compound, an epoxy group-containing polymerizable compound, an amide group-containing polymerizable compound, and an amino group-containing polymerizable compound.

Examples of hydroxyl group-containing polymerizable compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl. Contains hydroxyl groups such as (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxy-3-phenoxypropyl (meth)acrylate (meth) Acrylate; Vinyl ether compounds such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether; etc. can be mentioned.

Examples of the epoxy group-containing polymerizable compound include glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, and allyl glycidyl ether.

Examples of polymerizable compounds containing an amide group include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N-butyl(meth)acrylamide, N-methylol(meth)acrylamide, N -Methylolpropane (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-vinylformamide, etc.

Examples of the amino group-containing polymerizable compound include amino group-containing compounds such as primary amino group-containing (meth)acrylate, secondary amino group-containing (meth)acrylate, and tertiary amino group-containing (meth)acrylate. ) Acrylates, etc. can be mentioned.

Among these, hydroxyl group-containing (meth)acrylates are preferable, and hydroxyl group-containing (meth)acrylates having an aromatic ring, such as 2-hydroxy-3-phenoxypropyl (meth)acrylate, are more preferable.

The content of the polymerizable compound (a3) having a functional group in the composition for forming a buffer layer is not particularly limited, but is preferably 5 to 40% by mass relative to the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer. , more preferably 10 to 30 mass%, and even more preferably 15 to 25 mass%.

[Other polymerizable compounds]

The composition for forming a buffer layer may contain other polymerizable compounds other than components (a1) to (a3) within a range that does not impair the effect of the present invention.

Other polymerizable compounds include, for example, alkyl (meth)acrylate having an alkyl group having 1 to 20 carbon atoms; Vinyl compounds such as styrene, N-vinylpyrrolidone, and N-vinylcaprolactam; etc. can be mentioned.

Other polymerizable compounds may be used individually or in combination of two or more types.

The content of other polymerizable compounds in the composition for forming a buffer layer is not particularly limited, but is preferably 0 to 20% by mass, more preferably 0 to 20% by mass, based on the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer. is 0 to 10 mass%, more preferably 0 to 2 mass%.

[Photopolymerization initiator]

The composition for forming a buffer layer containing an energy ray polymerizable compound preferably further contains a photopolymerization initiator from the viewpoint of reducing the polymerization time and energy ray irradiation amount by energy ray irradiation.

The photopolymerization initiator may be used individually by 1 type, or may use 2 or more types together.

Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and further photosensitizers such as amines and quinones. Can be, more specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoinmethyl ether, benzoin Ethyl ether, benzoin isopropyl ether, benzylphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethyl Benzoyl) phenylphosphine oxide, etc. are mentioned. Among these, 1-hydroxycyclohexylphenyl ketone is preferable.

The content of the photopolymerization initiator in the composition for forming a buffer layer is not particularly limited, but is preferably 0.05 to 15 parts per 100 parts by mass of the total amount of the energy ray polymerizable compound from the viewpoint of making the energy ray curing reaction proceed homogeneously and sufficiently. Parts by mass, more preferably 0.1 to 10 parts by mass, and still more preferably 0.3 to 5 parts by mass.

(Other ingredients)

The composition for forming a buffer layer may contain other components as long as they do not impair the effects of the present invention. Other components include, for example, resin components other than the above resins; Additives such as antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, and dyes; etc. can be mentioned.

The content of other resin components in the composition for forming a buffer layer is not particularly limited, but is preferably 0 to 20% by mass, more preferably 0 to 20% by mass, based on the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer. It is 10 mass %, more preferably 0 to 2 mass %.

The content of other additives in the composition for forming a buffer layer is not particularly limited, but is preferably 0 to 6% by mass, more preferably 0 to 6% by mass, based on the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer for each. is 0.01 to 5 mass%, more preferably 0.1 to 3 mass%.

(Young’s modulus of buffer layer)

The Young's modulus of the buffer layer at 23°C is smaller than the Young's modulus of the base material at 23°C, and specifically, it is preferably less than 1,200 MPa, more preferably 900 MPa or less. Moreover, the Young's modulus of the buffer layer at 23°C is preferably 50 MPa or more, and more preferably 100 MPa or more.

If the Young's modulus at 23°C of the buffer layer is below the above upper limit, the effect of absorbing vibration, shock, etc. generated during back surface grinding and the retention of the adhesive sheet tend to improve. Additionally, if the Young's modulus at 23°C of the buffer layer is equal to or greater than the above lower limit, there is a tendency to suppress excessive deformation of the buffer layer when processing a workpiece.

In addition, the Young's modulus at 23°C of the buffer layer can be measured under the conditions of a test speed of 200 mm/min in accordance with JIS K 7127:1999.

(Stress relaxation rate of buffer layer)

The stress relaxation rate of the buffer layer is not particularly limited, but is preferably 70 to 100%, more preferably 75 to 100%, and still more preferably 78 to 98%.

If the stress relaxation rate of the buffer layer is within the above range, the effect of absorbing vibration, shock, etc. generated during backside grinding and the retention of the adhesive sheet tend to increase.

The stress relaxation rate of the buffer layer is the stress A (N/ m2), and the stress B (N/m2) 1 minute after the stoppage of elongation.

Stress relaxation rate (%) = 100 × (A-B)/A (%)

(thickness of buffer layer)

The thickness of the buffer layer is not particularly limited, but is preferably 10 to 70 μm, more preferably 15 to 50 μm, and even more preferably 20 to 40 μm.

If the thickness of the buffer layer is more than the above lower limit, the effect of absorbing vibration, shock, etc. generated during backside grinding and the retention of the adhesive sheet tend to increase. Additionally, if the thickness of the buffer layer is below the above upper limit, excessive deformation of the buffer layer when processing the workpiece tends to be suppressed.

＜Adhesive layer＞

The adhesive layer is a layer formed on the side opposite to the buffer layer of the substrate and is attached to the work.

The adhesive layer is preferably a layer formed of an energy ray-curable adhesive. By forming the adhesive layer with an energy-ray curable adhesive, the work surface can be well protected by sufficient adhesiveness before energy-ray curing, and after energy-ray curing, peeling force is reduced, making peeling from the work easier. there is.

Examples of the energy ray-curable adhesive include the following adhesive compositions of type X, type Y, and type XY.

Type

Y-type adhesive composition: Contains an energy-ray-curable adhesive resin (hereinafter also referred to as “Adhesive Resin II”) in which an unsaturated group is introduced into the side chain of the non-energy-ray-curable adhesive resin, and an energy-ray-curable compound other than the adhesive resin. Energy radiation curable adhesive composition that does not contain

XY type adhesive composition: Energy ray curable adhesive composition containing the above energy ray curable adhesive resin II and an energy ray curable compound other than the adhesive resin.

Among these, it is preferable that the energy ray curable adhesive is an XY type adhesive composition. By using an

The adhesive forming the adhesive layer may be a layer formed of a non-energy ray curable adhesive that does not harden even when irradiated with energy rays.

Examples of non-energy ray curable adhesives include ones that contain adhesive resin I but do not contain adhesive resin II and energy ray curable compounds.

Next, each component constituting the adhesive layer is explained in more detail.

In the following description, “adhesive resin” is used as a term referring to one or both of adhesive resin I and adhesive resin II. In addition, in the following description, when simply referred to as “adhesive composition”, the concept includes the X-type adhesive composition, Y-type adhesive composition, XY-type adhesive composition, and adhesive compositions other than these.

Examples of the adhesive resin include acrylic resin, urethane resin, rubber resin, and silicone resin. Among these, acrylic resin is preferable.

(Acrylic resin)

It is preferable that the acrylic resin contains a structural unit derived from alkyl (meth)acrylate.

Examples of the alkyl (meth)acrylate include alkyl (meth)acrylate in which the alkyl group has 1 to 20 carbon atoms.

The alkyl group contained in the alkyl (meth)acrylate may be linear or branched.

From the viewpoint of further improving the adhesive strength of the adhesive layer, the acrylic resin preferably contains a structural unit derived from an alkyl (meth)acrylate whose alkyl group has 4 or more carbon atoms.

The structural units derived from alkyl (meth)acrylate in which the alkyl group contained in the acrylic resin has 4 or more carbon atoms may be used alone or in combination of two or more types.

The carbon number of the alkyl group of the alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms is preferably 4 to 12, more preferably 4 to 8, and still more preferably 4 to 6.

Examples of alkyl (meth)acrylates having an alkyl group having 4 or more carbon atoms include butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, and isooctyl (meth)acrylate. Acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, undecyl (meth)acrylate, dodecyl (meth)acrylate, etc. are mentioned. Among these, butyl (meth)acrylate is preferable and butyl acrylate is more preferable.

When the acrylic resin contains a structural unit derived from alkyl (meth)acrylate in which the alkyl group has 4 or more carbon atoms, the content is preferably 30 to 30 in the acrylic resin from the viewpoint of further improving the adhesive strength of the adhesive layer. It is 90 mass%, more preferably 40 to 80 mass%, and further preferably 45 to 60 mass%.

From the viewpoint of improving the storage modulus G' and adhesive properties of the adhesive layer, the acrylic resin is an alkyl resin having a carbon number of 1 to 3 in the alkyl group together with a structural unit derived from an alkyl (meth)acrylate whose alkyl group has a carbon number of 4 or more. It is preferable to contain structural units derived from (meth)acrylate.

The structural units derived from alkyl (meth)acrylate whose alkyl group contained in the acrylic resin has 1 to 3 carbon atoms may be used alone or in combination of two or more.

Examples of alkyl (meth)acrylates in which the alkyl group has 1 to 3 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, and n-propyl (meth)acrylate. Rates, etc. can be mentioned. Among these, methyl (meth)acrylate and ethyl (meth)acrylate are preferable, methyl (meth)acrylate is more preferable, and methyl methacrylate is still more preferable.

When the acrylic resin contains a structural unit derived from alkyl (meth)acrylate whose alkyl group has 1 to 3 carbon atoms, the content is preferably 1 to 35% by mass, more preferably 5% by mass, in the acrylic resin. to 30 mass%, more preferably 15 to 25 mass%.

It is preferable that the acrylic resin further contains a structural unit derived from a functional group-containing monomer.

When the acrylic resin contains a structural unit derived from a functional group-containing monomer, a functional group as a crosslinking origin that reacts with a crosslinking agent is introduced, or a functional group that reacts with an unsaturated group-containing compound and makes it possible to introduce an unsaturated group into the side chain of the acrylic resin. can do.

The structural units derived from the functional group-containing monomer contained in the acrylic resin may be one type or two or more types.

Examples of functional group-containing monomers include hydroxyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, and epoxy group-containing monomers. Among these, hydroxyl group-containing monomers and carboxyl group-containing monomers are preferable, and hydroxyl group-containing monomers are more preferable.

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 2-hydroxybutyl (meth)acrylate. ) Hydroxyalkyl (meth)acrylates such as acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; Unsaturated alcohols such as vinyl alcohol and allyl alcohol; etc. can be mentioned.

Examples of the carboxyl group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid; Ethylenically unsaturated dicarboxylic acids and anhydrides thereof such as fumaric acid, itaconic acid, maleic acid, and citraconic acid; 2-carboxyethyl methacrylate; etc. can be mentioned.

When the acrylic resin contains a structural unit derived from a functional group-containing monomer, the content is not particularly limited, but is preferably 5 to 45% by mass, more preferably 15 to 40% by mass, in the acrylic resin. Typically, it is 25 to 35 mass%.

In addition to the structural units described above, the acrylic resin may contain structural units derived from other monomers copolymerizable with the acrylic monomer.

The structural units derived from other monomers contained in the acrylic resin may be used individually or in combination of two or more types.

Other monomers include, for example, styrene, α-methylstyrene, vinyl toluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

The acrylic resin may be one into which an unsaturated group having energy ray polymerizability has been introduced in order to further impart energy ray curability.

The unsaturated group is, for example, a functional group of an acrylic resin containing a structural unit derived from a functional group-containing monomer, a reactive substituent reactive with the functional group, and a compound having an unsaturated group (hereinafter also referred to as “unsaturated group-containing compound”). A reactive substituent can be introduced by reacting it. The unsaturated group-containing compound may be used individually by one type, or may be used in combination of two or more types.

Examples of the unsaturated group contained in the unsaturated group-containing compound include (meth)acryloyl group, vinyl group, and allyl group. Among these, (meth)acryloyl group is preferable.

Examples of the reactive substituent that the unsaturated group-containing compound has include an isocyanate group and glycidyl group.

Examples of the unsaturated group-containing compound include (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, and glycidyl (meth)acrylate.

When reacting an acrylic resin containing a structural unit derived from a functional group-containing monomer with an unsaturated group-containing compound, the ratio of the functional group that reacts with the unsaturated group-containing compound out of the total number of functional groups in the acrylic resin is not particularly limited, but is preferably It is 60 to 98 mol%, more preferably 70 to 95 mol%, and even more preferably 80 to 93 mol%.

If the ratio of the functional group that reacts with the unsaturated group-containing compound is within the above range, sufficient energy radiation curability can be imparted to the acrylic resin, and the acrylic resin can be crosslinked by reacting the functional group that does not react with the unsaturated group-containing compound with a crosslinking agent. You can.

The mass average molecular weight (Mw) of the acrylic resin is not particularly limited, but is preferably 300,000 to 1.5 million, more preferably 350,000 to 1 million, and even more preferably 400,000 to 600,000.

When the mass average molecular weight (Mw) of the acrylic resin is within the above range, the adhesive force and cohesive force of the adhesive layer tend to become better.

(Energy ray curable compound)

The energy ray-curable compound contained in the X-type or XY-type adhesive composition is preferably a monomer or oligomer that has an unsaturated group in the molecule and can be cured by energy ray irradiation.

Energy ray curable compounds include, for example, trimethylolpropane tri(meth)acrylate, pentaerythritol (meth)acrylate, pentaerythritol tetra(meth)acrylate, and dipentaerythritol hexa(meth)acrylate. , polyhydric (meth)acrylate monomers such as 1,4-butylene glycol di(meth)acrylate and 1,6-hexanediol (meth)acrylate; Oligomers such as urethane (meth)acrylate, polyester (meth)acrylate, polyether (meth)acrylate, and epoxy (meth)acrylate; etc. can be mentioned. Among these, urethane (meth)acrylate oligomer is preferable from the viewpoint of its relatively high molecular weight and difficulty in lowering the elastic modulus of the pressure-sensitive adhesive layer.

The molecular weight of the energy ray curable compound is not particularly limited, but is preferably 100 to 12,000, more preferably 200 to 10,000, further preferably 400 to 8,000, and still more preferably 600 to 6,000. In addition, when the energy-ray curable compound is an oligomer, the molecular weight means mass average molecular weight (Mw).

The content of the energy ray curable compound in the type is 60 to 90 parts by mass.

If the content of the energy ray curable compound in the type

The content of the energy ray curable compound in the is 3 to 15 parts by mass.

If the content of the energy ray curable compound in the In addition, since the adhesive resin of the

(Cross-linking agent)

It is preferable that the adhesive composition further contains a crosslinking agent.

The crosslinking agent crosslinks the adhesive resins, for example, by reacting with a functional group derived from a functional group-containing monomer of the adhesive resin.

A crosslinking agent may be used individually by 1 type, or may use 2 or more types together.

Examples of the crosslinking agent include isocyanate-based crosslinking agents such as tolylene diisocyanate, hexamethylene diisocyanate, and adducts thereof; Epoxy-based crosslinking agents such as ethylene glycol glycidyl ether; Aziridine-based crosslinking agents such as hexa[1-(2-methyl)-aziridinyl]triphosphatriazine; Chelate-based crosslinking agents such as aluminum chelate; etc. can be mentioned. Among these, an isocyanate-based crosslinking agent is preferable from the viewpoint of increasing cohesion and further improving adhesive strength and ease of availability.

When the adhesive composition contains a crosslinking agent, the content is not particularly limited, but is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, based on 100 parts by mass of the adhesive resin, from the viewpoint of appropriately advancing the crosslinking reaction. Parts by mass, more preferably 0.05 to 4 parts by mass.

(Photopolymerization initiator)

When the adhesive is an energy-ray curable adhesive, it is preferable that the adhesive composition further contains a photopolymerization initiator. When the energy ray curable adhesive contains a photopolymerization initiator, the curing reaction of the energy ray curable adhesive tends to proceed sufficiently even with relatively low energy energy rays such as ultraviolet rays.

The photopolymerization initiator may be used individually by 1 type, or may use 2 or more types together.

Examples of photopolymerization initiators include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and further photosensitizers such as amines and quinones. Can be, more specifically, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoinmethyl ether, benzoin Ethyl ether, benzoin isopropyl ether, benzylphenylsulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, bis(2,4,6-trimethyl Benzoyl) phenylphosphine oxide, etc. are mentioned.

When the energy ray curable adhesive contains a photopolymerization initiator, the content is not particularly limited, but is preferably 0.01 to 10 parts by mass per 100 parts by mass of the adhesive resin from the viewpoint of advancing the energy ray curing reaction homogeneously and sufficiently. , More preferably 0.03 to 7 parts by mass, Still more preferably 0.05 to 5 parts by mass.

(Other additives)

The adhesive composition may contain other additives as long as they do not impair the effects of the present invention. Other additives include, for example, antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, dyes, etc.

The content of other additives in the adhesive composition is not particularly limited, but is preferably 0 to 6% by mass, more preferably 0.01 to 5% by mass, based on the total amount (100% by mass) of the active ingredients of the adhesive composition. % by mass, more preferably 0.1 to 3% by mass.

In addition, in this embodiment, the active ingredient of the adhesive composition means the component contained in the adhesive composition excluding components such as organic solvents removed in the process of forming the adhesive layer.

(organic solvent)

From the viewpoint of further improving applicability to substrates, release sheets, etc., the adhesive composition may be diluted with an organic solvent and may be in the form of a solution.

Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, etc.

Organic solvents may be used individually or in combination of two or more types.

As the organic solvent, the organic solvent used during synthesis of the adhesive resin may be used as is, or one or more organic solvents other than the organic solvent used during synthesis may be added.

The storage modulus G' of the adhesive layer at 23°C is not particularly limited, but is preferably 0.05 to 0.5 MPa, more preferably 0.1 to 0.4 MPa, and still more preferably 0.12 to 0.3 MPa.

If the storage modulus G' of the adhesive layer at 23°C is in the above range, even when the surface of the work has irregularities, an adhesive layer with excellent followability to the uneven shape can be obtained, and the surface of the work can be maintained more favorably during processing. There is a tendency to protect.

In addition, the storage elastic modulus G' of the adhesive layer means the storage elastic modulus G' before curing by energy ray irradiation when the adhesive layer is formed of an energy ray curable adhesive.

The storage elastic modulus G' of the adhesive layer at 23°C was measured by a torsional shear method using a viscoelasticity measuring device using a test piece cut from a 3 mm thick adhesive layer into a circle with a diameter of 8 mm, at a frequency of 1 Hz and at a measurement temperature. It can be measured under conditions of 23°C.

The thickness of the adhesive layer is not particularly limited, but is preferably 5 to 100 μm, more preferably 10 to 80 μm, and still more preferably 15 to 60 μm.

If the thickness of the adhesive layer is more than the above lower limit, excellent adhesiveness is obtained and the surface of the workpiece tends to be better protected during processing. In addition, if the thickness of the adhesive layer is below the above upper limit, the generation of tape scraps when cutting the adhesive sheet is suppressed, and damage to the workpiece tends to be better prevented.

<Description>

Examples of the base material include various resin films. Resins constituting the resin film include, for example, polyethylene such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and high-density polyethylene (HDPE); Polyolefins such as polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymer, and norbornene resin; Ethylene-based copolymers such as ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, and ethylene-(meth)acrylic acid ester copolymer; Polyvinyl chloride, such as polyvinyl chloride and vinyl chloride copolymer; Polyesters such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, and wholly aromatic polyester; Polyurethane, polyimide, polyamide, polycarbonate, fluororesin, polyacetal, modified polyphenylene oxide, polyphenylene sulfide, polysulfone, polyether ketone, acrylic polymer; etc. can be mentioned.

The base material may be a single-layer film of a resin film made of one or two or more types of resins selected from these resins, or may be a laminated film in which two or more types of these resin films are laminated. Additionally, it may be a modified film such as a crosslinked film of the above resin or an ionomer film.

Among these resin films, the base material is preferably at least one selected from polyester film, polyamide film, polyimide film and biaxially oriented polypropylene film, more preferably polyester film, and even more preferably polyethylene terephthalate film. desirable.

The Young's modulus of the base material is not particularly limited, but is preferably 1,000 MPa or more, more preferably 1,800 to 30,000 MPa, and even more preferably 2,500 to 6,000 MPa.

If the Young's modulus of the base material is more than the above lower limit, the vibration suppression effect during work processing tends to be further improved. Additionally, if the Young's modulus of the base material is below the above upper limit, workability when affixing to a work and workability when peeling from the work tend to be good.

Additionally, the Young's modulus of the substrate can be measured under the conditions of a test speed of 200 mm/min in accordance with JIS K 7127:1999.

The thickness of the base material is not particularly limited, but is preferably 10 to 200 μm, more preferably 25 to 100 μm, and still more preferably 30 to 70 μm.

If the thickness of the base material is equal to or greater than the above lower limit, sufficient strength to function as a support for the adhesive sheet tends to be obtained. Additionally, if the thickness of the base material is below the above upper limit, appropriate flexibility is obtained and handling properties tend to improve.

In addition, “substrate thickness” means the thickness of the entire substrate, and when the substrate is a substrate composed of multiple layers, it means the total thickness of all layers constituting the substrate.

The base material may contain a plasticizer, a lubricant, an infrared absorber, an ultraviolet ray absorber, a filler, a colorant, an antistatic agent, an antioxidant, a catalyst, etc., within the range that does not impair the effect of the present invention.

The substrate may be transparent or opaque, and may be colored or vapor-deposited as desired.

From the viewpoint of improving adhesion to other layers, the base material may be subjected to surface treatment such as corona treatment on at least one side, or may be formed with a coating layer for the purpose of improving adhesion.

<Release sheet>

The adhesive sheet of this embodiment may have a release sheet affixed to at least one of the surface of the adhesive layer and the surface of the surface coat layer. The release sheet is peelably attached to the surface of the adhesive sheet before use to protect the surface, and is peeled off and removed when the adhesive sheet is used.

The peeling sheet may be a peeling sheet that has undergone a single-side peeling treatment, or may be a peeling sheet that has undergone a double-sided peeling treatment.

As a release sheet, a release sheet obtained by applying a release agent to a base material for the release sheet is preferably used.

As a base material for a release sheet, a resin film is preferable, and examples of the resin film include polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate film; Polyolefin films such as polypropylene film and polyethylene film; etc. can be mentioned.

Examples of the release agent include rubber-based elastomers such as silicone-based resin, olefin-based resin, isoprene-based resin, and butadiene-based resin; Long-chain alkyl-based resins, alkyd-based resins, fluorine-based resins, etc. can be mentioned.

The thickness of the release sheet is not particularly limited, but is preferably 5 to 200 μm, more preferably 10 to 100 μm, and still more preferably 20 to 50 μm.

The total thickness of the adhesive sheet of this embodiment is not particularly limited, but is preferably 30 to 300 μm, more preferably 40 to 220 μm, and still more preferably 45 to 160 μm.

If the total thickness of the adhesive sheet is more than the above lower limit, the adhesive performance of the adhesive layer, the shock absorption performance of the buffer layer, etc. are maintained appropriately, and the function as an adhesive sheet for semiconductor processing tends to be sufficiently exhibited. Additionally, if the total thickness of the adhesive sheet is below the above upper limit, the peeling force when peeling the work from the adhesive sheet tends to be reduced.

In addition, in this embodiment, “total thickness of the adhesive sheet” means the thickness from the surface of the surface coat layer of the adhesive sheet to the surface of the adhesive layer, and when a release sheet is formed, the total thickness of the release sheet is Not included in thickness.

＜Manufacturing method of adhesive sheet＞

There is no particular limitation on the manufacturing method of the adhesive sheet of this embodiment, and it can be manufactured by a known method.

The adhesive sheet of the present embodiment includes, for example, a step of forming an adhesive layer on one side of the substrate (hereinafter also referred to as “adhesive layer forming step”), and a step of forming a buffer layer on the other side of the substrate (hereinafter also referred to as “adhesive layer forming step”). , It can be manufactured by a method including a step of forming a surface coat layer on the side opposite to the base of the buffer layer (hereinafter also referred to as a "surface coat layer formation step"). Additionally, the order of these processes is not particularly limited, and if they can be performed simultaneously, they may be performed simultaneously.

The adhesive layer forming step may be, for example, a method of bonding an adhesive layer formed on a release sheet to the surface of a substrate, or a method of forming the adhesive layer by directly applying an adhesive composition to the surface of the substrate. You can continue.

The buffer layer forming step may be, for example, a method of bonding a buffer layer formed on a release sheet to the surface of a substrate, or may be a method of forming a buffer layer by directly applying a composition for forming a buffer layer to the surface of the substrate.

The surface coat layer forming step may be, for example, a method of bonding a surface coat layer formed on a release sheet to the surface of a buffer layer on a substrate, or by directly applying a coating liquid for a surface coat layer to the surface of the buffer layer on the substrate to form a surface coat layer. A method of forming a coat layer may be used.

Additionally, the buffer layer forming step and the surface coat layer forming step may be a method of forming a surface coat layer and a buffer layer in this order on a release sheet and then bonding the buffer layer to the surface of the substrate.

A method of forming an adhesive layer, a buffer layer, or a surface coat layer on a release sheet includes, for example, applying an adhesive composition, a composition for forming a buffer layer, or a coating liquid for a surface coat layer on a release sheet by a known method. , and, if necessary, methods such as energy ray irradiation, heat drying, etc.

Methods for applying the adhesive composition, the composition for forming a buffer layer, or the coating liquid for the surface coat layer include, for example, spin coat method, spray coat method, bar coat method, knife coat method, roll coat method, blade coat method, and die coat method. Examples include the gravure coat method and the like.

When the composition for forming a buffer layer contains an energy ray polymerizable compound, the curing treatment by energy ray irradiation may be performed once or may be performed multiple times.

When performing the curing treatment once, after forming a coating film of the composition for forming a buffer layer on a substrate, the composition for forming a buffer layer may be completely cured by irradiation with energy rays, or after completely curing the composition for forming a buffer layer on a release sheet. , you may bond this to the substrate.

When the curing treatment is carried out in multiple stages, after forming a coating film of the composition for forming a buffer layer on the release sheet, the composition for forming a buffer layer is not completely cured on the release sheet, but is cured to a semi-cured state and then applied to the substrate. After bonding, the composition for forming a buffer layer may be completely cured by irradiating the energy ray again.

Additionally, ultraviolet rays are preferable as the energy ray irradiated in the curing treatment of the composition for forming a buffer layer.

When curing the composition for forming a buffer layer, the coating film of the composition for forming a buffer layer may be exposed to the outside, but it is preferable to irradiate the energy ray while the coating film is covered with a release sheet or base material and the coating film is not exposed to the outside. .

＜Use of adhesive sheet＞

Processing of the workpiece performed while the adhesive sheet of the present embodiment is attached includes, for example, back grinding, which involves grinding the other side of a semiconductor device while the adhesive sheet is attached to one side of the semiconductor device. Examples include dicing processing to separate the semiconductor device into individual pieces with an adhesive sheet attached to one side, transportation of the semiconductor device, and pickup of semiconductor chips. Among these, the adhesive sheet of this embodiment is preferable for back grind processing, and is more preferable for back grind processing in which the back surface of a semiconductor wafer is ground while the adhesive sheet of this embodiment is affixed to the circuit formation surface of the semiconductor wafer. In particular, the adhesive sheet of this embodiment has the effect of suppressing the occurrence of cracks when thinning a semiconductor wafer, and is therefore suitable for processes such as the line dicing method and the stealth line dicing method.

[Manufacturing method of semiconductor device]

The manufacturing method of the semiconductor device of this embodiment is:

A step of attaching the adhesive sheet for semiconductor processing of this embodiment to the surface of a semiconductor wafer using the adhesive layer as an attachment surface;

A process of grinding the back side of the semiconductor wafer while the surface coat layer side of the adhesive sheet for semiconductor processing attached to the semiconductor wafer is fixed by a support device,

A method of manufacturing a semiconductor device comprising:

In addition, the manufacturing method of the semiconductor device of this embodiment includes:

A process for forming a line to be divided, which is a process a for forming a groove on the surface of a semiconductor wafer, or a process b for forming a modified area inside the semiconductor wafer from the front or back surface of the semiconductor wafer;

A sheet attaching step of attaching the adhesive sheet for semiconductor processing of the present embodiment to the surface of the semiconductor wafer using the adhesive layer as an attachment surface after the step a, or before or after the step b;

With the surface coat layer side of the adhesive sheet for semiconductor processing attached to the semiconductor wafer being fixed by a support device, the back side of the semiconductor wafer is ground and divided into a plurality of semiconductor chips using the groove or modified area as a starting point. , grinding and granulating process,

It is preferable that it is a semiconductor device manufacturing method including.

Moreover, the manufacturing method of the semiconductor device of this embodiment may include a peeling process of peeling the adhesive sheet for semiconductor processing of this embodiment from a plurality of semiconductor chips after the grinding and segmentation process.

In addition, the manufacturing method of the semiconductor device having the above-mentioned process a is a process corresponding to the line dicing method, and the manufacturing method of the semiconductor device having the above-described process b is a process corresponding to the stealth line dicing method.

Examples of semiconductor wafers used in the manufacturing method of this embodiment include silicon wafers, gallium arsenide wafers, gallium nitride wafers, silicon carbide wafers, glass wafers, and sapphire wafers. Among these, silicon wafers are preferable.

Circuits such as wiring, capacitors, diodes, and transistors are usually formed on the surface of a semiconductor wafer. These circuits can be formed by conventionally known methods, such as an etching method or a lift-off method.

The thickness of the semiconductor wafer before grinding is not particularly limited, but is usually 500 to 1,000 μm.

Hereinafter, each step of the semiconductor device manufacturing method of this embodiment will be described in detail.

<Divide line formation process>

The division line formation process is process a of forming a groove on the surface of a semiconductor wafer, or process b of forming a modified region inside the semiconductor wafer from the front or back surface of the semiconductor wafer.

Step a is a step of forming a groove on the surface of the semiconductor wafer, and is performed before attaching the adhesive sheet to the surface of the semiconductor wafer.

The groove formed on the surface of the semiconductor wafer in step a is a groove whose depth is shallower than the thickness of the semiconductor wafer. After step a, the semiconductor wafer is back-ground until it reaches the groove formed in step a, and is divided into a plurality of semiconductor chips. Therefore, in step a, the groove is formed along the dividing line when the semiconductor wafer is divided into individual semiconductor chips.

The grooves can be formed by dicing using a conventionally known wafer dicing device or the like.

Step b is a step of forming a modified region inside the semiconductor wafer from the front or back side of the semiconductor wafer, and may be performed before or after attaching the adhesive sheet to the surface of the semiconductor wafer.

In step b, the modified region is formed inside the semiconductor wafer by irradiation of a laser focused on the inside of the semiconductor wafer. The modified area is a part of the semiconductor wafer that has become nitrided, and is destroyed by the semiconductor wafer being thinned by back grinding or applying force by grinding, and the semiconductor wafer is broken into individual semiconductor chips. This is the starting point. Therefore, the modified region is formed along the division line when the semiconductor wafer is divided into individual semiconductor chips.

Laser irradiation may be performed from the front side of the semiconductor wafer, or may be performed from the back side. When step b is performed after the sheet sticking step, the semiconductor wafer may be irradiated with a laser through the adhesive sheet.

<Sheet attaching process>

The sheet sticking process is a process of sticking the adhesive sheet to the surface of the semiconductor wafer using the adhesive layer as the sticking surface after step a, or before or after step b.

The method of sticking the adhesive sheet is not particularly limited, and for example, a conventionally known method using a laminator or the like can be applied.

<Grinding and fragmentation process>

In the grinding and segmentation process, the back side of the semiconductor wafer is ground while the surface coat layer side of the adhesive sheet attached to the semiconductor wafer is fixed by a support device, and the groove or modified area is used as a starting point to form a plurality of semiconductor chips. It is a process of reorganization.

A semiconductor wafer on which an adhesive sheet is attached and grooves or modified regions are formed is fixed on the surface coat layer side of the adhesive sheet by a support device. The support device is not particularly limited, but is preferably a device that suctions and holds a fixed object such as a chuck table.

Next, the back side of the fixed semiconductor wafer is ground, and the semiconductor wafer is divided into a plurality of semiconductor chips.

Back grinding grinds the semiconductor wafer to at least a position where the grinding surface reaches the bottom of the groove when a groove is formed in the semiconductor wafer in step a. By this back grinding, the groove becomes an incision that penetrates the wafer, and the semiconductor wafer is divided by the incision and divided into individual semiconductor chips.

On the other hand, when a modified region is formed in the semiconductor wafer by process b, the ground surface may reach the modified region, but does not have to strictly reach the modified region. In other words, starting from the modified area, the semiconductor wafer is broken and broken into semiconductor chips by grinding to a position close to the modified area. For example, after grinding the semiconductor wafer to a position close to the modified area without breaking it into pieces, attaching a pickup tape to the semiconductor wafer, and stretching the pickup tape, the wafer may be broken into pieces into semiconductor chips.

The shape of the individualized semiconductor chip may be square, or may be an elongated shape such as a rectangle.

The thickness of the divided semiconductor chip is not particularly limited, but is preferably 5 to 100 μm, more preferably 7 to 70 μm, and still more preferably 10 to 45 μm.

The chip size of the discrete semiconductor chip is not particularly limited, but is preferably less than 50 mm2, more preferably less than 30 mm2, and even more preferably less than 10 mm2.

<Peeling process>

The peeling process is a process of peeling the adhesive sheet from a plurality of semiconductor chips after the grinding and segmentation process.

When the adhesive layer of the adhesive sheet is formed of an energy ray-curable adhesive, the adhesive is cured by irradiating energy rays to reduce the peeling force of the adhesive layer, and then the adhesive sheet is peeled.

Additionally, when peeling off the adhesive sheet, you may use a pickup tape. A pickup tape is comprised, for example, of an adhesive sheet including a base material and an adhesive layer formed on one side of the base material.

When using a pickup tape, first, the pickup tape is attached to the back side of the separated semiconductor wafer, and the position and orientation are aligned to enable pickup. At this time, it is preferable to also bond the ring frame disposed on the outer peripheral side of the semiconductor wafer to the pickup tape and fix the outer peripheral edge portion of the pickup tape to the ring frame. Next, the adhesive tape is peeled from the plurality of semiconductor chips fixed on the pickup tape.

Thereafter, a plurality of semiconductor chips on a pickup tape may be picked up and then fixed on a substrate or the like to manufacture a semiconductor device.

Example

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Measurement methods and evaluation methods for various physical properties are as follows.

[Mass average molecular weight (Mw)]

The mass average molecular weight (Mw) was measured under the following conditions using a gel permeation chromatograph (manufactured by Tosoh Corporation, product name "HLC-8220"), and calculated in standard polystyrene conversion.

(Measuring conditions)

Column:「TSK guard column HXL-H」「TSK gel GMHXL(×2)」「TSK gel G2000HXL」(all manufactured by Tosoh Corporation)

·Column temperature: 40℃

·Developing solvent: tetrahydrofuran

·Flow rate: 1.0 mL/min

[Measurement of thickness of adhesive sheets, etc.]

The total thickness of the adhesive sheet, the thickness of each layer, and the thickness of the test piece manufactured therefrom were measured using a static pressure thickness meter (product name "PG-02", manufactured by Techlock Co., Ltd.). At this time, 10 random points were measured and the average value was calculated.

In addition, the total thickness of the adhesive sheet is a value obtained by measuring the thickness of the adhesive sheet with the release sheet attached and subtracting the thickness of the release sheet from the thickness.

Additionally, the thickness of the buffer layer is the value obtained by subtracting the thickness of the base material from the thickness of the base material on which the buffer layer is formed.

In addition, the thickness of the surface coat layer is the value obtained by subtracting the thickness of the release sheet from the thickness of the surface coat layer to which the release sheet is attached.

Additionally, the thickness of the adhesive layer is the total thickness of the adhesive sheet minus the thicknesses of the surface coat layer, buffer layer, and base material.

[Measurement of water contact angle of surface coat layer]

The water contact angle of the surface coat layer was measured based on JIS R 3257:1999. Specifically, the release sheet on the surface coat layer side of the adhesive sheet manufactured in the examples and comparative examples was peeled off, and the static contact angle was measured when purified water was dropped on the exposed surface of the exposed surface coat layer using a fully automatic contact angle measuring meter (Kyo). and Interface Science Co., Ltd. (product name “DM-701”) was used to measure under the following conditions.

·Measuring temperature: 23℃

·Drop volume of purified water: 2 μl

·Measurement time: 1 second after dropping

·Image analysis method: θ/2 method

[Evaluation of the amount of grinding debris adhesion to the surface coat layer]

The adhesive sheets prepared in Examples and Comparative Examples were cut into 5 cm x 5 cm, and the release sheet on the surface coat layer side was peeled off to prepare a test piece exposing the surface coat layer. One of the four corners of the test piece was fixed and hung, and immersed in grinding water containing 2% by mass of silicon wafer grinding chips for 1 minute. The test piece was taken out from the grinding water, left hanging at 23°C for 24 hours to dry, then the surface coat layer of the test piece was visually observed, and the amount of grinding debris attached was evaluated based on the following criteria. In addition, in the following evaluation criteria, “grinding debris attachment point” means an island-shaped grinding debris attachment point formed by drying droplets of grinding water adhering to the surface coat layer.

A: There is one place on the surface coat layer where grinding chips adhere, or grinding chips do not adhere to a degree that can be identified as a grinding chip adhered area.

B: There are 2 to 5 attachment portions of grinding chips on the surface coat layer.

C: There are six or more places where grinding chips adhere to the surface coat layer, but no grinding chips adhere to the entire surface of the surface coat layer.

D: Grinding debris adheres to the entire surface of the surface coat layer.

[Preparation of urethane acrylate-based oligomer used in buffer layer]

Manufacturing Example 1

The terminal isocyanate urethane prepolymer obtained by reacting polyester diol and isophorone diisocyanate was reacted with 2-hydroxyethyl acrylate to obtain a bifunctional urethane acrylate-based oligomer with a mass average molecular weight (Mw) of 5,000.

[Preparation of energy ray-curable acrylic resin used in adhesive layer]

Production example 2

An acrylic polymer was obtained by copolymerizing 52 parts by mass of n-butylacrylate, 20 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate. Next, 2-methacryloyloxyethyl isocyanate was reacted so as to add 90 mol% of hydroxyl groups in the total hydroxyl groups of the acrylic polymer, and an energy ray-curable acrylic resin with a mass average molecular weight (Mw) of 500,000 was obtained.

[Manufacture of adhesive sheet]

Examples 1 to 3, Comparative Examples 1 to 3

Next, an adhesive sheet was manufactured by the method shown below. In addition, the compounding quantity of each component in the following description all means the compounding quantity of the active ingredient.

(1) Preparation of materials

As a base material, a polyethylene terephthalate film (Young's modulus: 2500 MPa) with a thickness of 50 μm was prepared.

(2) Preparation of coating liquid for surface coat layer

In Examples 1 to 3 and Comparative Examples 1 to 2, the resin shown in Table 1 was dissolved in toluene so that the active ingredient concentration was 10% by mass, and was used as a coating liquid for the surface coat layer.

Comparative Example 3 was prepared by dissolving and dispersing 100 parts by mass of the resin shown in Table 1 and 30 parts by mass of silica filler (manufactured by Nissan Chemical Industries, Ltd., brand name “Snowtex (registered trademark) UP”) in toluene so that the active ingredient concentration was 5% by mass. This was used as a coating liquid for the surface coat layer.

(3) Preparation of composition for forming buffer layer

40 parts by mass of the urethane acrylate-based oligomer obtained in Production Example 1, 40 parts by mass of isobornyl acrylate, 20 parts by mass of 2-hydroxy-3-phenoxypropyl acrylate, and 1-hydroxycyclohexylphenyl ketone as a photopolymerization initiator. A composition for forming a buffer layer was prepared by mixing 2.0 parts by mass and 0.2 parts by mass of a phthalocyanine-based pigment.

(4) Preparation of adhesive composition

100 parts by mass of energy-ray-curable acrylic resin obtained in Production Example 2, multifunctional urethane acrylate, which is an energy-ray-curable compound (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., brand name “Cicco UT-4332”, mass average molecular weight (Mw) 4,700) 6 0.375 parts by mass of an isocyanate-based crosslinking agent (manufactured by Tosoh Corporation, brand name "Colonate L"), and 1 part by mass of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as a photopolymerization initiator were mixed and diluted with a solvent. By doing so, an adhesive composition was prepared.

(5) Manufacturing of adhesive sheets

After applying the composition for forming a buffer layer obtained above to one side of the substrate shown above, the composition for forming a buffer layer is cured by irradiating ultraviolet rays under the conditions of an illumination intensity of 160 mW/cm2 and an irradiation amount of 500 mJ/cm2, and then curing the composition for forming a buffer layer on one side of the substrate. A substrate having a buffer layer with a thickness of 13 μm was formed on the surface of the substrate.

In addition, the adhesive composition obtained above was applied to the peeling surface of a release sheet (manufactured by Lintech Co., Ltd., brand name "SP-PET381031") so that the thickness after drying was 20 μm, and then heated and dried to form a peeling adhesive layer. A sheet was manufactured. The adhesive layer of the release sheet on which the adhesive layer was formed was attached to the side of the base material on which the buffer layer was formed on which the buffer layer was not formed, thereby producing a laminate having the buffer layer, the base material, and the adhesive layer in this order.

In addition, the coating liquid for the surface coat layer obtained above was applied to the peeling treated surface of the release sheet (manufactured by Lintech Co., Ltd., brand name "SP-PET381031") with a Meyer bar so that the thickness after drying was 2 ㎛, and then heated and dried. A surface coat layer to which a release sheet was attached was prepared. The surface coat layer of the surface coat layer to which the release sheet was attached was affixed to the surface of the buffer layer of the laminate to obtain a pressure-sensitive adhesive sheet having the surface coat layer, buffer layer, base material, and pressure-sensitive adhesive layer in this order.

The evaluation results conducted using the adhesive sheets obtained in each Example and Comparative Example are shown in Table 1.

Maleic anhydride modified polyolefin resin: propylene-butene-maleic anhydride copolymer, maleic anhydride modification ratio: 1.5 mass%, mass average molecular weight (Mw): 75,000, hetero atom content: 0.735 mass%, manufactured by Toyobo Co., Ltd., Product name「Toyo Tak (registered trademark) PMA-L」

· Ethylene-cyclic olefin copolymer: Ethylene-tetracyclododecene copolymer, content of structural units derived from tetracyclododecene: 20 to 32 mol%, heteroatom content: 5.2 mass%, manufactured by Mitsui Chemicals Co., Ltd., brand name 「Apel (registered trademark) APL6509T」

· Ethylene-vinyl acetate copolymer: Vinyl acetate content: 14% by mass, heteroatom content: 0% by mass, manufactured by Toyobo Co., Ltd., brand name “Ultracen (registered trademark) 685”

・Polyester resin: manufactured by Toyobo Co., Ltd., product name: “Byron (registered trademark) GK-680”

・Polyester urethane resin: manufactured by Toyobo Co., Ltd., product name “Byron (registered trademark) UR-4410”

·Epoxy acrylate resin: manufactured by Arkema, brand name “CN104 NS”

From Table 1, it can be seen that the adhesive sheets of Examples 1 to 3 in which the water contact angle of the surface coat layer is 85 degrees or more have sufficiently reduced the amount of grinding debris adhesion. On the other hand, the adhesive sheets of Comparative Examples 1 to 3 in which the water contact angle of the surface coat layer was less than 85° did not sufficiently reduce the amount of grinding debris adhesion.

Claims (11)

It has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order,
An adhesive sheet for semiconductor processing, wherein the static contact angle of water at 23°C with respect to the surface coat layer is 85° or more. According to claim 1,
An adhesive sheet for semiconductor processing, wherein the surface coat layer is an organic layer containing a resin component. According to claim 2,
An adhesive sheet for semiconductor processing, wherein the resin component is a thermoplastic resin. According to claim 2 or 3,
An adhesive sheet for semiconductor processing, wherein the resin component has a heteroatom content of 7% by mass or less. According to any one of claims 2 to 4,
An adhesive sheet for semiconductor processing, wherein the resin component dissolves 1% by mass or more in toluene at 23°C. The method according to any one of claims 1 to 5,
An adhesive sheet for semiconductor processing, wherein the static contact angle of water at 23°C with respect to the surface coat layer is 90° or more. The method according to any one of claims 1 to 6,
An adhesive sheet for semiconductor processing, wherein the surface coat layer has a thickness of 0.05 to 10 μm. The method according to any one of claims 1 to 7,
An adhesive sheet for semiconductor processing, wherein the buffer layer is formed from a composition for forming a buffer layer containing urethane (meth)acrylate. The method according to any one of claims 1 to 8,
Adhesive sheet for semiconductor processing, used for back side grinding of semiconductor wafers. A step of attaching the adhesive sheet for semiconductor processing according to any one of claims 1 to 9 on the surface of a semiconductor wafer using the adhesive layer as an attachment surface;
A method of manufacturing a semiconductor device, comprising the step of grinding the back surface of the semiconductor wafer while the surface coat layer side of the adhesive sheet for semiconductor processing attached to the semiconductor wafer is fixed by a support device. According to claim 10,
A process for forming a line to be divided, which is a process a for forming a groove on the surface of a semiconductor wafer, or a process b for forming a modified area inside the semiconductor wafer from the front or back surface of the semiconductor wafer;
After the step a, or before or after the step b, the adhesive sheet for semiconductor processing according to any one of claims 1 to 9 is attached to the surface of the semiconductor wafer using the adhesive layer as a sticking surface. , sheet attaching process,
With the surface coat layer side of the adhesive sheet for semiconductor processing attached to the semiconductor wafer being fixed by a support device, the back side of the semiconductor wafer is ground and divided into a plurality of semiconductor chips using the groove or modified area as a starting point. A method of manufacturing a semiconductor device, comprising a grinding and segmentation process.