KR20240032655A - Adhesive sheet for semiconductor processing and method of manufacturing semiconductor device - Google Patents

Abstract

It has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order, wherein the surface coat layer contains a styrene-based resin, and the content of structural units derived from a styrene-based compound in the styrene-based resin is 50 mass. % or more, relates to an adhesive sheet for semiconductor processing and a method of manufacturing a semiconductor device using the adhesive sheet for semiconductor processing.

Description

Adhesive sheet for semiconductor processing and manufacturing method of semiconductor device {ADHESIVE SHEET FOR SEMICONDUCTOR PROCESSING AND METHOD OF MANUFACTURING 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 involves attaching an adhesive sheet for semiconductor processing (hereinafter referred to as “back grind sheet”) for back grinding to the surface of the semiconductor wafer, and protecting the surface of the semiconductor wafer with the sheet. It is carried out. 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, adhesive sheets for semiconductor processing are also required to have a function for thinning semiconductor chips with good 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, in the adhesive sheet for semiconductor processing, a buffer layer may be formed to absorb vibration, shock, etc. that occurs when processing a workpiece such as a semiconductor wafer and to prevent damage to the workpiece.

The buffer layer is made of a material that is more deformable than the base material, and is formed on the surface opposite to the adhesive layer of the base material. Therefore, scratches may occur unintentionally during production of adhesive sheets for semiconductor processing, processing of workpieces, etc. there is. In order to prevent this, it is effective to form a surface coat layer on the surface opposite to the substrate of the buffer layer.

In addition, the surface coat layer may play a role in suppressing the adhesion of grinding debris in addition to preventing the occurrence of scratches in the buffer layer. For example, when back grinding a workpiece, the back grind sheet is fixed to a support device such as a chuck table. If grinding debris exists between the back grind sheet and the table of the support device, the portion where the grinding debris exists is the starting point. Therefore, cracks may occur in the work due to shock when fixing the work to the table, pressure during back grinding, vibration, etc. The occurrence of the above problem can be suppressed by forming a surface coat layer capable of suppressing adhesion of grinding debris on the surface of the back grind sheet on the side fixed to the support device.

However, according to the present inventors' examination, when a work is attached to an adhesive sheet for semiconductor processing having a surface coating layer and predetermined processing is performed while the surface coating layer is fixed to a support device, the adhesive sheet for semiconductor processing adheres after processing. It has been found that there are cases where the workpiece fails to be lifted from the support device and cannot be transported. This is thought to be due to excessive adhesion of the surface coating layer to the support device due to pressure, heat, etc. when processing the workpiece.

The present invention was made in view of the above-mentioned circumstances, and its purpose is to provide an adhesive sheet for semiconductor processing with excellent transportability after work processing 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 that has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order and has a specific structure or properties. completed the present invention.

That is, the present invention relates to the following [1] to [27].

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

The surface coat layer contains a styrene-based resin,

An adhesive sheet for semiconductor processing, wherein the content of structural units derived from a styrene-based compound in the styrene-based resin is 50% by mass or more.

[2] The adhesive sheet for semiconductor processing according to [1] above, wherein the content of structural units derived from styrene-based compounds in the styrene-based resin is 80% by mass or less.

[3] The styrene-based resin is styrene-butadiene block copolymer, styrene-ethylene-propylene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene- The adhesive sheet for semiconductor processing according to [1] or [2] above, which is at least one member selected from the group consisting of styrene block copolymers and styrene-ethylene-propylene-styrene block copolymers.

[4] The adhesive sheet for semiconductor processing according to any one of [1] to [3] above, wherein the mass average molecular weight (Mw) of the styrene resin is 10,000 to 600,000.

[5] The adhesive sheet for semiconductor processing according to any one of [1] to [4] above, wherein the surface coat layer has a thickness of 0.05 to 10 μm.

[6] The adhesive sheet for semiconductor processing according to any one of [1] to [5] above, wherein the buffer layer is a layer formed from a composition for forming a buffer layer containing urethane (meth)acrylate.

[7] The adhesive sheet for semiconductor processing according to any one of [1] to [6] above, which is used for backside grinding of a semiconductor wafer.

[8] A process of attaching the adhesive sheet for semiconductor processing according to any one of [1] to [7] 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.

[9] 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 [7] 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 the groove or the modified region is used as a starting point to form a plurality of semiconductor chips. A method of manufacturing a semiconductor device comprising grinding, grinding, and segmentation processes.

[10] 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 storage modulus E' of the surface coat layer at 90°C is 100 MPa or more.

[11] The adhesive sheet for semiconductor processing according to [10], wherein the surface coat layer is an organic layer containing a resin component.

[12] The adhesive sheet for semiconductor processing according to [11] above, wherein the resin component is a thermoplastic resin.

[13] The adhesive sheet for semiconductor processing according to [12] above, wherein the thermoplastic resin is a polymer of a compound having one or more ethylenically unsaturated bonds.

[14] The adhesive sheet for semiconductor processing according to any one of [10] to [13], wherein the surface coating layer has a thickness of 0.05 to 10 μm.

[15] The adhesive sheet for semiconductor processing according to any one of [10] to [14] above, wherein the buffer layer is a layer formed from a composition for forming a buffer layer containing urethane (meth)acrylate.

[16] The adhesive sheet for semiconductor processing according to any one of [10] to [15] above, which is used for backside grinding of a semiconductor wafer.

[17] A process of attaching the adhesive sheet for semiconductor processing according to any one of [10] to [16] 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.

[18] 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 step a, or before or after step b, the adhesive sheet for semiconductor processing according to any one of [10] to [16] 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 the groove or the modified region is used as a starting point to form a plurality of semiconductor chips. A method of manufacturing a semiconductor device comprising grinding, grinding, and segmentation processes.

[19] 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 difference between the haze value after heat treatment under the following conditions and the haze value before the heat treatment (haze value after heat treatment - haze value before heat treatment) is 2.0% or less.

(Conditions of heat treatment)

A metal plate (1) having a polished surface is placed on a hot plate whose temperature is maintained at 90°C with the polished surface facing upward, and a release sheet is applied to the adhesive layer on the polished surface of the metal plate (1). The attached adhesive sheet for semiconductor processing is placed in the direction in which the surface coat layer is on the polished surface side, and on the release sheet of the adhesive sheet for semiconductor processing, a metal plate having a polished surface on the side in contact with the release sheet ( 2) The adhesive sheet for semiconductor processing is heat-treated at 90°C for 1 minute by laminating the weight and the weight in this order.

The adhesive sheet for semiconductor processing used in the heat treatment has a rectangular shape in plan view and a size of 5 cm × 5 cm in plan view, and both the metal plate 1 and the metal plate 2 are made of SUS304. First, the shape in the plan view is rectangular, the size in the plan view is 7 cm The weight is assumed to have a circular cylindrical shape with a weight of 1 kg and a bottom diameter of 4 cm. The metal plate (1), the adhesive sheet for semiconductor processing, and the metal plate (2) are placed so that their four sides are parallel to each other, and the metal plate (1), the adhesive sheet for semiconductor processing, the metal plate (2), and the weight are , the positions of each center point as seen from the plane are arranged so that they coincide.

[20] The adhesive sheet for semiconductor processing according to [19] above, wherein the surface coat layer is an organic layer containing a resin component.

[21] The adhesive sheet for semiconductor processing according to [20] above, wherein the resin component is a thermoplastic resin.

[22] The adhesive sheet for semiconductor processing according to [21], wherein the thermoplastic resin is a polymer of a compound having one or more ethylenically unsaturated bonds.

[23] The adhesive sheet for semiconductor processing according to any one of [19] to [22], wherein the surface coating layer has a thickness of 0.05 to 10 μm.

[24] The adhesive sheet for semiconductor processing according to any one of [19] to [23] above, wherein the buffer layer is a layer formed from a composition for forming a buffer layer containing urethane (meth)acrylate.

[25] The adhesive sheet for semiconductor processing according to any one of [19] to [24] above, which is used for backside grinding of a semiconductor wafer.

[26] A process of attaching the adhesive sheet for semiconductor processing according to any one of [19] to [25] 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.

[27] 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 step a, or before or after step b, the adhesive sheet for semiconductor processing according to any one of [19] to [25] 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 the groove or the modified region is used as a starting point to form a plurality of semiconductor chips. A method of manufacturing a semiconductor device comprising grinding, grinding, and segmentation processes.

According to the present invention, it is possible to provide an adhesive sheet for semiconductor processing with excellent transportability after work processing and a method for manufacturing a semiconductor device using the adhesive sheet for semiconductor processing.

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, “active ingredient” refers to the ingredients contained in the composition in question, excluding the diluting solvent.

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 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” means the property of hardening by irradiating an energy ray, and “non-energy ray curability” means the property of not having energy ray hardenability.

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 of the first embodiment of the present invention has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order, the surface coat layer contains a styrene resin, and the styrene resin contains It is an adhesive sheet for semiconductor processing with a content of structural units derived from a styrene-based compound of 50% by mass or more.

The adhesive sheet for semiconductor processing of the second embodiment of the present invention has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order, and the storage modulus E' at 90°C of the surface coat layer is 100 MPa or more, This is an adhesive sheet for semiconductor processing.

The adhesive sheet for semiconductor processing of the third embodiment of the present invention has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order, and has a haze value after heat treatment in the above “(heat treatment conditions)” and the heat treatment. It is an adhesive sheet for semiconductor processing in which the difference in haze value before treatment [haze value after heat treatment - haze value before heat treatment] is 2.0% or less.

Hereinafter, unless otherwise specified, the “adhesive sheet of the present embodiment” refers to the adhesive sheet for semiconductor processing of the first embodiment of the present invention, the adhesive sheet for semiconductor processing of the second embodiment of the present invention, and the adhesive sheet of the present invention. Let it refer to the third character of the adhesive sheet for semiconductor processing of the third embodiment.

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 has excellent transportability after workpiece processing. The cause is not certain, but it is assumed to be as follows.

It is believed that the conventional surface coat layer melts and deforms due to heat and pressure during work processing, and its adhesion to the support device becomes too large, resulting in a decrease in transportability after work processing. In contrast, the adhesive sheet of this embodiment is thought to have improved transportability after workpiece processing as follows.

The surface coat layer of the pressure-sensitive adhesive sheet of the first embodiment of the present invention contains a styrene-based resin having a content of structural units derived from styrene-based compounds of 50% by mass or more, and the styrene-based resin has excellent heat resistance, It is thought that deformation and melting of the surface coating layer during work processing were suppressed. As a result, it is assumed that the adhesion to the support device does not increase too much and the transportability after workpiece processing becomes good.

In addition, since the surface coating layer of the adhesive sheet of the second embodiment of the present invention has a storage modulus E' of 100 MPa or more at 90°C, deformation, melting, etc. due to heat and pressure during work processing are suppressed. It is thought that it has been done. As a result, it is assumed that the adhesion to the support device does not increase too much and the transportability after workpiece processing becomes good.

In addition, the present inventors conducted studies on suppressing deterioration of the surface coat layer due to heat, pressure, etc., and found that the difference in haze value before and after heat treatment under specific conditions can be used as an index of deterioration of the surface coat layer. and completed the adhesive sheet of the third embodiment of the present invention. That is, in the adhesive sheet of the third embodiment of the present invention, the haze difference before and after the heat treatment is 2.0% or less, so that deformation and melting of the surface coating layer during processing of the workpiece are suppressed, and thus, the support device It is presumed that the adhesion to the workpiece did not increase excessively, and the transportability after workpiece processing became good.

In addition, the pressure-sensitive adhesive sheet of the present embodiment has an additional effect of suppressing whitening of the pressure-sensitive adhesive sheet after heating. Conventional pressure-sensitive adhesive sheets formed with a surface coating layer may whiten due to heat during work processing, which may cause problems such as deterioration of appearance and reduction of energy ray permeability. On the other hand, since whitening is suppressed in the adhesive sheet of this embodiment, it is excellent in appearance and energy ray permeability even after work processing.

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 surface coat layer, buffer layer, substrate, and adhesive layer include, for example, an intermediate layer formed between the substrate and the adhesive layer, and a release sheet formed on the side of the adhesive layer opposite to the substrate.

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.

The surface coat layer of the adhesive sheet of the first embodiment of the present invention is a styrene-based resin (hereinafter also referred to as “styrene-based resin (S)”) having a content of structural units derived from styrene-based compounds of 50% by mass or more. Contains. On the other hand, the surface coat layer of the adhesive sheet of the second and third embodiments of the present invention may be an inorganic layer or an organic layer, but from the viewpoint of productivity and handleability of the adhesive sheet, it is preferable to be an organic layer, and the resin It is more preferable that it is an organic layer containing a component, it is still more preferable that it is an organic layer containing a thermoplastic resin, and it is especially preferable that it contains a styrene-type resin (S).

(Styrene-based resin (S))

The styrene-based resin (S) is not particularly limited as long as it is a resin with a content of structural units derived from a styrene-based compound of 50% by mass or more.

The styrene-based resin (S) may be used individually or in combination of two or more types.

Examples of the styrene-based compound include substituted or unsubstituted styrene.

Examples of the substituent substituted by styrene include an aliphatic hydrocarbon group having 1 to 5 carbon atoms, a halogen atom, and an alkoxy group having 1 to 5 carbon atoms.

Examples of styrene-based compounds include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, chlorostyrene, and methoxystyrene. Among these, styrene is preferable.

The content of structural units derived from the styrene-based compound in the styrene-based resin (S) is 50% by mass or more.

When the content of the structural unit derived from the styrene-based compound in the styrene-based resin (S) is 50% by mass or more, the adhesive sheet of this embodiment has excellent transportability after work processing. Additionally, there is a tendency to suppress whitening of the adhesive sheet after heating.

From the above viewpoint, the content of the structural unit derived from the styrene-based compound in the styrene-based resin (S) is preferably 55% by mass or more, more preferably 60% by mass or more.

In addition, the content of the structural unit derived from the styrene-based compound in the styrene-based resin (S) is not particularly limited, but is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass. It is less than mass%.

If the content of the structural unit derived from the styrene-based compound is below the above upper limit, it tends to be easy to adjust the balance with performance other than the transportability of the adhesive sheet by introducing structural units other than the structural unit derived from the styrene-based compound. There is.

Structural units other than structural units derived from styrene-based compounds that the styrene-based resin (S) may contain include compounds having one or more ethylenically unsaturated bonds other than styrene-based compounds.

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.

Compounds other than styrene-based compounds having one or more ethylenically unsaturated bonds include, for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, Chain monoolefins such as 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 5-methyl-1-hexene; Chain non-conjugated dienes (non-conjugated diolefins) such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene; 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 (conjugated diene) olefin) ; 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[7.4.0.1 ^{10,13.0 2,7} ]trideca-2,4,6 , polycyclic olefins such as 11-tetraene; Monomers having oxygen atoms and ethylenically unsaturated bonds, such as maleic anhydride and vinyl acetate, monomers having nitrogen atoms and ethylenically unsaturated bonds, such as maleimide compounds and nitrile-based monomers, etc. can be mentioned.

Among the above options, it is preferable that the styrene-based resin (S) contains a structural unit derived from a conjugated diene.

The structural unit derived from the conjugated diene includes a structural unit formed by addition polymerization of the conjugated diene, a structural unit formed by hydrogenating a structural unit formed by addition polymerization of the conjugated diene, etc.

Structural units formed by hydrogenating a structural unit formed by addition polymerization of a conjugated diene include, for example, an ethylene-propylene unit formed by hydrogenating a structural unit formed by addition polymerization of isoprene, and 1,3-butadiene by addition polymerization. An ethylene-butylene unit formed by hydrogenating the structural unit formed as follows.

When the styrene-based resin (S) contains a structural unit derived from a conjugated diene, its content in the styrene-based resin (S) is not particularly limited, but is preferably 20 to 50% by mass, more preferably It is 25 to 45 mass%, more preferably 30 to 40 mass%.

If the content of the structural unit derived from the conjugated diene in the styrene resin (S) is more than the above lower limit, the amount of grinding debris adhesion tends to be further reduced. Moreover, if the content of the structural unit derived from the conjugated diene in the styrene resin (S) is below the above upper limit, the transportability after work processing tends to be good.

The styrene-based resin (S) is styrene-butadiene block copolymer, styrene-ethylene-propylene block copolymer, styrene-butadiene-styrene block copolymer, and styrene-isoprene-block copolymer from the viewpoint of transportability and grinding debris adhesion after work processing. Selected from the group consisting of styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer (hereinafter also referred to as “SEBS”) and styrene-ethylene-propylene-styrene block copolymer (hereinafter also referred to as “SEPS”) At least one type selected from the group consisting of styrene-ethylene-butylene-styrene block copolymer and styrene-ethylene-propylene-styrene block copolymer is more preferred.

The mass average molecular weight (Mw) of the styrene resin (S) is not particularly limited, but is preferably 10,000 to 600,000, more preferably 15,000 to 500,000, and still more preferably 20,000 to 400,000.

If the mass average molecular weight (Mw) of the styrene resin (S) is equal to or greater than the above lower limit, the transportability after work processing tends to be better. Moreover, if the mass average molecular weight (Mw) of the styrene resin (S) is below the above upper limit, the solvent solubility of the styrene resin (S) improves, and formation of a surface coat layer by application tends to become easy.

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 content of the styrene resin (S) in the surface coat layer is not particularly limited, but is preferably 30 to 95% by mass, more preferably 40 to 90% by mass, based on the total amount (100% by mass) of the surface coat layer. % by mass, more preferably 45 to 85% by mass.

If the content of the styrene resin (S) is more than the above lower limit, the transportability after work processing tends to be better, and whitening of the adhesive sheet after heating tends to be more suppressed. Additionally, if the content of the styrene resin (S) is below the above upper limit, the adhesion between the buffer layer and the surface coat layer tends to be improved more easily.

Thermoplastic resins other than the styrene-based resin (S) that the surface coat layer may contain include, for example, 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. The preferable mass average molecular weight (Mw) of thermoplastic resins other than these styrene resins (S) is the same as the preferable mass average molecular weight (Mw) of the styrene resin (S).

The content of the resin component in the surface coat layer is not particularly limited, but is preferably 30 to 95% by mass, more preferably 40 to 90% by mass, based on the total amount (100% by mass) of the surface coat layer. Preferably it is 45 to 85 mass%.

If the content of the resin component is more than the above lower limit, the transportability after work processing tends to be better, and whitening of the adhesive sheet after heating tends to be more suppressed. Additionally, if the content of the resin component is below the above upper limit, the adhesion between the buffer layer and the surface coat layer tends to be improved more easily.

(Hyphophobized silica)

It is preferable that the surface coat layer further contains silica that has been subjected to hydrophobization treatment.

Since the surface coat layer contains silica subjected to hydrophobization treatment, the adhesive sheet of this embodiment tends to have a reduced amount of grinding debris adhesion.

The hydrophobization-treated silica may be used individually or in combination of two or more types.

Examples of silica that has been subjected to hydrophobization treatment include raw material silica that has been surface treated with a hydrophobization treatment agent.

The raw material silica to be hydrophobized may be, for example, wet-processed silica produced by a wet process such as a precipitation method, gel method, or sol-gel method, or may be dry-processed silica such as fumed silica or fused silica. Among these, wet-processed silica is preferable and precipitated-processed silica is more preferable from the viewpoint of easy hydrophobization.

Examples of hydrophobization treatment agents include organosilicon compounds, fatty acids, and fatty acid metal salts.

The hydrophobization treatment agent may be used individually as one type, or may be used in combination of two or more types.

Methods for surface treating raw silica with a hydrophobization treatment agent include, for example, a method of contacting the raw silica with a hydrophobization treatment agent in a solvent, a method of contacting the vapor of the hydrophobization treatment agent returned by a carrier gas such as nitrogen with the raw silica, and hydrophobization. A method of bringing the stock solution of the treatment agent into direct contact with the raw material silica may be mentioned.

The shape of the hydrophobized silica is not particularly limited, and examples include spherical and irregular shapes. Among these, an irregular shape is preferable from the viewpoint of further reducing the amount of grinding debris adhesion.

As hydrophobized silica, for example, “AEROSIL (registered trademark) series” manufactured by Evonic Corporation, “QSG series” manufactured by Shin-Etsu Chemical Co., Ltd., and “Nipsil (registered trademark) SS series” manufactured by Tosoh Silica Co., Ltd. , the “SYLOPHOBIC (registered trademark) series” manufactured by Fuji Cilicia Chemical Co., Ltd., etc. are commercially available.

When the surface coat layer contains silica that has been hydrophobized, the content of silica that has been hydrophobized in the surface coat layer is not particularly limited, but is preferably 1 to 150 parts by mass based on 100 parts by mass of the styrene resin (S). parts, more preferably 10 to 120 parts by mass, further preferably 20 to 100 parts by mass, and even more preferably 30 to 90 parts by mass.

If the content of hydrophobized silica is more than the above lower limit, the amount of grinding debris adhesion tends to be further reduced. Additionally, if the content of hydrophobized silica is below the above upper limit, the film forming properties of the surface coat layer tend to improve.

The surface coat layer may contain components other than the styrene resin (S) and the hydrophobized silica.

For example, the surface coat layer is irradiated with energy rays to a composition containing an energy ray polymerizable multifunctional compound and a photopolymerization initiator together with the styrene resin (S) from the viewpoint of improving adhesion to the buffer layer. It is preferable that it is a layer formed by doing so.

In addition, in the following description, the composition used for forming the surface coat layer may be referred to as “composition for forming the surface coat layer.”

(Energy ray polymerizable multifunctional compound)

An energy ray polymerizable multifunctional compound is a compound having two or more energy ray polymerizable functional groups.

The energy ray-polymerizable multifunctional compound may be used individually by one type, or may be used in combination of two or more types.

The number of energy ray polymerizable functional groups that the energy ray polymerizable multifunctional compound has is preferably 2 to 10, more preferably 3 to 8, and still more preferably 4 to 7.

As the energy ray polymerizable functional group contained in the energy ray polymerizable multifunctional compound, (meth)acryloyl group is preferable.

As the energy ray polymerizable multifunctional compound, a polyfunctional (meth)acrylate monomer is preferable.

Examples of polyfunctional (meth)acrylate monomers include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, Polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, neopentyl glycol di(meth)acrylate hydroxypivalic acid, dicyclopentanyl di(meth)acrylate, caprolactone modified dicyclo Pentenyl di(meth)acrylate, ethylene oxide modified phosphoric acid di(meth)acrylate, di(acryloxyethyl)isocyanurate, allylated cyclohexyl di(meth)acrylate, ethylene oxide isocyanuric acid modified diacrylate. Bifunctional (meth)acrylate monomers such as latex; Trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide modified trimethylolpropane Tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, bis(acryloxyethyl)hydroxyethyl isocyanurate, isocyanuric acid ethylene oxide modified triacrylate, ε-caprolactone modified tris( Acryloxyethyl)isocyanurate, diglycerin tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, propionic acid modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate salt, caprolactone-modified dipentaerythritol hexa(meth)acrylate, etc. Among these, dipentaerythritol hexa(meth)acrylate and dipentaerythritol penta(meth)acrylate are preferable, and dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate are more preferable.

When the composition for forming a surface coat layer contains an energy ray polymerizable multifunctional compound, the content of the energy ray polymerizable multifunctional compound is preferably 10 to 60 parts by mass based on 100 parts by mass of the styrene resin (S). , More preferably 14 to 40 parts by mass, Still more preferably 17 to 30 parts by mass.

If the content of the energy-ray polymerizable multifunctional compound is more than the above lower limit, the surface coat layer tends to have excellent adhesion to the buffer layer. In addition, if the content of the energy-ray polymerizable multifunctional compound is below the above upper limit, there is a tendency to easily achieve a good balance between the adhesion to the buffer layer and the transportability after work processing.

(Photopolymerization initiator)

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.

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

When the composition for forming a surface coat layer contains a photopolymerization initiator, the content is not particularly limited, but from the viewpoint of advancing the energy ray polymerization reaction homogeneously and sufficiently, the amount is preferably 100 parts by mass of the energy ray polymerizable multifunctional compound. Preferably it is 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 5 parts by mass.

(Other ingredients)

The surface coat layer may contain other components other than those mentioned above within a range that does not impair the effects of the present invention. Other components include, for example, resins other than those mentioned above; Additives such as antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, and dyes; etc. can be mentioned.

(Storage modulus E’ of surface coat layer at 90°C)

The storage modulus E' at 90°C of the surface coat layer of the adhesive sheet of the second embodiment of the present invention is 100 MPa or more. In addition, the storage modulus E' at 90°C of the surface coating layer of the pressure-sensitive adhesive sheets of the first and third embodiments of the present invention is preferably 100 MPa or more.

If the storage modulus E' of the surface coat layer at 90°C is 100 MPa or more, the adhesive sheet of this embodiment has excellent transportability after work processing.

The storage modulus E' of the surface coating layer at 90°C is preferably 120 MPa or more, more preferably 150 MPa or more, and still more preferably 170 MPa or more from the viewpoint of improving the transportability after work processing. am. In addition, the storage modulus E' of the surface coat layer at 90°C is not particularly limited, but is preferably 1,500 MPa or less, more preferably 1,000 MPa or less, even more preferably 800 MPa or less, and even more preferably It is less than 600 MPa. If the storage modulus E' of the surface coat layer at 90°C is below the above upper limit, a pressure-sensitive adhesive sheet with appropriate flexibility is easy to obtain, and the handling properties of the pressure-sensitive adhesive sheet tend to be excellent.

In addition, the storage modulus E' of the surface coat layer at 90°C can be measured by the method described in the Examples.

(Thickness of surface coat layer)

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 equal to or greater than the above lower limit, uniform layer formation becomes possible and the transportability after work processing tends to improve. 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.

In addition, in this specification, the number of ring-forming atoms refers to the number of atoms constituting the ring itself of a compound having a structure in which atoms are bonded in a ring, and refers to the number of atoms constituting the ring itself (e.g., atoms not constituting the ring (e.g., atoms constituting the ring) bonded hydrogen atom), and atoms included in the substituent when the ring is substituted by a substituent are not included in the number of ring forming atoms.

[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.

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, even more preferably. It is either 1 or 2.

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. there is. 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 at 60 to 100°C in the presence of an organic solvent, catalyst, etc. added as necessary. This can be done under the condition of time reaction.

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%.

[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.

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 10 based on the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer. It is 70 mass%, more preferably 20 to 60 mass%, and further preferably 30 to 50 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 mass based on 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 by mass based on 100 parts by mass of the energy ray polymerizable compound from the viewpoint of advancing the energy ray curing reaction homogeneously and sufficiently. , More preferably 0.1 to 10 parts by mass, 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; Other additives such as antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, and dyes; etc. can be mentioned.

(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 less than 1,000 MPa, and still more preferably less than 900 MPa. 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.

Additionally, 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/ m ² ), and the stress B (N/m ² ) 1 minute after the stop of elongation can be used to obtain the value from the following formula.

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

(thickness of buffer layer)

The thickness of the buffer layer is not particularly limited, but is preferably 5 to 70 μm, more preferably 7 to 50 μm, and still more preferably 10 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, the 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 an “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 among the total number of functional groups in the acrylic resin is not particularly limited, but is preferably 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 at the same time, 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 tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and 1,4-butylene glycol di. Polyhydric (meth)acrylate monomers such as (meth)acrylate and 1,6-hexanediol di(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 be used in combination of 2 or more types.

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 adhesive composition contains a photopolymerization initiator, the content is not particularly limited, but is preferably 0.01 to 10 parts by mass, based on 100 parts by mass of the adhesive resin, from the viewpoint of advancing the energy beam curing reaction homogeneously and sufficiently. Preferably it is 0.03 to 7 parts by mass, 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.

(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 using 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, “thickness of the base material” means the thickness of the entire base material, and when the base material is a base material made of multiple layers, it means the total thickness of all the layers constituting the base material.

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.

<Total thickness of adhesive sheet>

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, the “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.

<Haze difference before and after heat treatment of adhesive sheet>

The pressure-sensitive adhesive sheet of the third embodiment of the present invention has a difference between the haze value after heat treatment under the following conditions and the haze value before the heat treatment (haze value after heat treatment - haze value before heat treatment) of 2.0% or less. am. In addition, in the adhesive sheets of the first and second embodiments of the present invention, it is preferable that the difference in haze value (haze value after heat treatment - haze value before heat treatment) is 2.0% or less.

(Conditions of heat treatment)

A metal plate (1) having a polished surface is placed on a hot plate whose temperature is maintained at 90°C with the polished surface facing upward, and a release sheet is applied to the adhesive layer on the polished surface of the metal plate (1). The attached adhesive sheet for semiconductor processing is placed in the direction in which the surface coat layer is on the polished surface side, and on the release sheet of the adhesive sheet for semiconductor processing, a metal plate having a polished surface on the side in contact with the release sheet ( 2) The adhesive sheet for semiconductor processing is heat-treated at 90°C for 1 minute by laminating the weight and the weight in this order.

The adhesive sheet for semiconductor processing used in the heat treatment has a rectangular shape in plan view and a size of 5 cm × 5 cm in plan view, and both the metal plate 1 and the metal plate 2 are made of SUS304. First, the shape in the plan view is rectangular, the size in the plan view is 7 cm The weight is assumed to have a circular cylindrical shape with a weight of 1 kg and a bottom diameter of 4 cm. The metal plate (1), the adhesive sheet for semiconductor processing, and the metal plate (2) are placed so that their four sides are parallel to each other, and the metal plate (1), the adhesive sheet for semiconductor processing, the metal plate (2), and the weight are , the positions of each center point as seen from the plane are arranged so that they coincide.

If the haze difference before and after the heat treatment is 2.0% or less, the adhesive sheet of this embodiment has excellent transportability after work processing.

The haze difference before and after the heat treatment is preferably 1.6% or less, more preferably 1.3% or less, and even more preferably 1.0% or less from the viewpoint of improving transportability after workpiece processing.

In addition, the lower limit of the haze difference before and after the heat treatment is not particularly limited, but may be 0%, and from the viewpoint of ease of manufacture, may be 0.1% or more, or 0.2% or more.

Additionally, the haze difference before and after heat treatment can be measured by the method described in the Examples.

The haze value of the adhesive sheet of this embodiment before heat treatment under the above conditions is not particularly limited, but is preferably 4 to 10%.

In addition, the haze value of the adhesive sheet of the present embodiment after heat treatment under the above conditions is not particularly limited, but is preferably 4 to 12%, more preferably 4.5 to 10%, and even more preferably 5 to 9%. % am.

If the haze value before heat treatment and the haze value after heat treatment are within the above range, the appearance and energy ray permeability of the adhesive sheet of this embodiment can be improved, and freedom in material selection tends to be easily obtained.

＜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 the “adhesive layer forming step”) and a step of forming a buffer layer on the other side of the substrate (hereinafter also referred to as the “adhesive layer forming step”). , "buffer layer formation step"), and a step of forming a surface coat layer on the side opposite to the substrate of the buffer layer (hereinafter also referred to as "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.

A method of forming an adhesive layer, a buffer layer, or a surface coat layer includes, for example, applying an adhesive composition, a composition for forming a buffer layer, or a composition for forming a surface coat layer at a predetermined location by a known method, and then applying the same method as necessary. Therefore, methods such as energy ray irradiation, heat drying, etc. can be mentioned.

Methods for applying the adhesive composition, the composition for forming a buffer layer, or the composition for forming a 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. A coat method, a gravure coat method, etc. may be mentioned.

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.

In the buffer layer forming step, the composition for forming a buffer layer may be applied on a release sheet or may be applied directly to the surface of the substrate. When the composition for forming a buffer layer is applied on a release sheet, the layer formed from the composition for forming a buffer layer on the release sheet (hereinafter also referred to as “composition layer for forming a buffer layer”) is then attached to the surface of the substrate. The composition layer for forming a buffer layer on the release sheet may be the buffer layer itself, or, if the composition for forming a buffer layer has curability, it may be an uncured or semi-cured product of the composition for forming a buffer layer that has curability. When an uncured or semi-cured product of the composition for forming a buffer layer is formed on a substrate, a treatment is performed to completely cure the composition for forming a buffer layer.

In the surface coat layer forming step, the composition for forming the surface coat layer may be applied on a release sheet or directly on the surface of the buffer layer. When applying the composition for forming a surface coat layer on a release sheet, the layer formed from the composition for forming a surface coat layer on the release sheet (hereinafter also referred to as the “composition layer for forming a surface coat layer”) is then applied to the buffer layer. It is attached to the surface. The composition layer for forming a surface coat layer on the release sheet may be the surface coat layer itself, or, if the composition for forming a surface coat layer has curability, it may be an uncured or semi-cured product of a composition for forming a surface coat layer that has curability. do. When an uncured or semi-cured product of the composition for forming a surface coat layer is formed on the buffer layer, a treatment is then performed to completely cure the composition for forming a surface coat layer.

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.

When the composition for forming a buffer layer contains an energy ray polymerizable compound, the buffer layer forming step preferably includes a step of irradiating the composition for forming a buffer layer with an energy ray.

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 the curing treatment by energy ray irradiation is performed once, after forming a coating film of the buffer layer forming composition on the substrate, the buffer layer forming composition may be completely cured by energy ray irradiation, or the buffer layer forming composition may be applied on the release sheet. After completely curing, this may be bonded to the substrate.

When the composition for forming a surface coat layer contains an energy ray polymerizable compound, the surface coat layer forming step preferably includes a step of irradiating the composition for forming a surface coat layer with an energy ray. The timing of irradiating energy rays to the composition for forming a surface coat layer is not particularly limited, and may be any time before or after lamination of the composition for forming a surface coat layer on a buffer layer or a composition layer for forming a buffer layer.

When the curing treatment of the composition for forming a buffer layer 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 left to a semi-cured state. After curing, the composition for forming a buffer layer may be completely cured by bonding it to the composition layer for forming a surface coat layer formed on a release sheet, and then irradiating the energy ray again. When the composition for forming a surface coat layer contains an energy ray polymerizable compound, the composition for forming a surface coat layer may be simultaneously cured by irradiating energy rays to completely cure the composition for forming a buffer layer.

In addition, ultraviolet rays are preferable as the energy ray irradiated in the curing treatment of the composition for forming a buffer layer and the composition for forming a surface coat layer.

When curing the composition for forming a buffer layer and the composition for forming a surface coat layer by irradiating energy rays, the composition for forming a buffer layer and the composition for forming a surface coat layer may be exposed to the outside, but both sides may be exposed to a release sheet, a substrate, etc. It is desirable to irradiate the energy line in a state where it is covered by a member and 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 method of manufacturing a semiconductor device including a 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.

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 the groove or the modified region is used as a starting point to form a plurality of semiconductor chips. It is preferable that it is a semiconductor device manufacturing method that includes grinding and segmentation processes.

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 a plurality of semiconductor chips are formed using the groove or the modified region as a starting point. 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 mm ² , more preferably less than 30 mm ² , and even more preferably less than 10 mm ² .

<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.

[Method for measuring 90°C storage modulus E’ of surface coat layer]

The composition for forming a surface coat layer prepared in the examples and comparative examples was applied using a Mayer bar to the peeling surface of a release sheet (manufactured by Lintech Co., Ltd., brand name “SP-PET381031”) so that the thickness of the surface coat layer formed was 35 μm. After application, it was heated and dried to form a composition layer for forming a surface coat layer on the release sheet.

By irradiating ultraviolet rays to the composition layer for forming a surface coating layer under the conditions of an illuminance of 160 mW/cm ² and an irradiation amount of 500 mJ/cm ² , the composition for forming a surface coating layer is cured to form a surface coating layer on which a release sheet is formed. Manufactured.

The release sheet was peeled and removed from the surface coat layer on which the release sheet obtained above was formed, and the surface coat layer was cut to have a width of 4 mm in plan view and a length of 30 mm between the chucks of a measuring device, which were used as test pieces. Using the test piece, the storage modulus E' of the surface coat layer at 90°C was measured using the following apparatus and measurement conditions.

Measuring device: “LeoVibron DDV-01FP” manufactured by A&D Co., Ltd.

Frequency: 1 Hz

Measurement temperature range: -10 ∼ 120 ℃

Temperature increase rate: 3℃/min

[Measurement of haze difference before and after heat treatment and evaluation of whitening of the adhesive sheet after heating]

The adhesive sheet having a release sheet on both sides prepared in the examples and comparative examples was cut into a rectangular shape of 5 cm × 5 cm in plan view, and only the release sheet on the surface coat layer side was peeled to expose the surface coat layer. Ready.

In addition, the metal plate 1 and the metal plate 2 are made of SUS304, have a rectangular shape in a plan view, have a size of 7 cm × 15 cm in a plan view, a thickness of 0.5 mm, a weight of 40 g, and a polished surface of 600 g. A weight having a surface finished by polishing, weighing 1 kg, and having a circular cylindrical base with a diameter of 4 cm was prepared.

The metal plate 1 is placed on a hot plate whose temperature is maintained at 90°C with the polished surface facing upward, and the test piece is placed on the polished surface of the metal plate 1 so that the surface coat layer is that of the metal plate 1. It was placed in the direction toward the polished surface. Additionally, on the release sheet of the test piece placed on the metal plate 1, a metal plate 2 having a polished surface on the side in contact with the release sheet and a weight are laminated in this order, and the test piece is heated at 90°C for 1 minute. Heat treatment was performed.

In addition, the metal plate 1, the test piece, and the metal plate 2 were placed so that each of their four sides were parallel to each other. In addition, the metal plate 1, the test piece, the metal plate 2, and the weight were placed so that the positions of their respective center points when viewed from the plane coincided.

The release sheet on the surface coat layer side of the heat-treated test piece was peeled off to obtain a heat-treated adhesive sheet, and the presence or absence of whitening of the adhesive sheet was confirmed by visual observation. Additionally, the haze value of the adhesive sheet was measured using a haze meter (manufactured by Nippon Denshoku Industries, Ltd., brand name “NDH-5000”) in accordance with JIS K 7136:2000. Additionally, separately, the haze value of the adhesive sheet before heat treatment was measured in the same manner as above, and the difference between the haze value after heat treatment and the haze value before heat treatment was calculated as [haze value after heat treatment - haze value before heat treatment]. was calculated.

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

The adhesive sheet having a release sheet on both sides prepared in the examples and comparative examples was cut to a size of 5 cm by 5 cm in plan view, and the release sheet on the surface coat layer side was peeled to prepare a test piece in which the surface coat layer was exposed. . 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 10 minutes. 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 portion” 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.

[Evaluation of transportability]

The release sheet on the adhesive layer side of the adhesive sheet having release sheets on both sides prepared in the examples and comparative examples was peeled off, and the exposed adhesive layer was used as the attachment surface to form a silicon mirror wafer (diameter 12 inches, thickness 50 ㎛, dry polish). finishing) to produce a silicon mirror wafer with an adhesive sheet (hereinafter also referred to as a “wafer with an adhesive sheet”).

The release sheet was peeled from the surface coating layer of the wafer to which the adhesive sheet was attached, placed on a heating table so that the surface coating layer became a contact surface, and heated at 80°C for 3 minutes. Thereafter, the suction surface of the transfer arm provided with the suction surface by the suction mechanism is placed on the surface of the silicon mirror wafer side of the wafer to which the adhesive sheet is attached, and the wafer to which the adhesive sheet is attached is suctioned and adsorbed. In this state, it was tested whether it was possible to lift the wafer with the adhesive sheet attached from the heating table, and the transportability was evaluated based on the following criteria.

A: The wafer with the adhesive sheet attached was able to be lifted from the heating table by the transfer arm.

B: The wafer with the adhesive sheet attached was in close contact with the heating table, and the wafer with the adhesive sheet attached could not be lifted from the heating table by the transfer arm.

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

Manufacturing example 1

A 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 4, Comparative Examples 1 to 2

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 substrate, a polyethylene terephthalate film (Young's modulus: 2,500 MPa) with a thickness of 50 μm was prepared.

(2) Preparation of composition for forming surface coat layer

Each component shown in Table 1 was dissolved in toluene so that the active ingredient concentration was 10 mass% to obtain a composition for forming a 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 the energy ray-curable acrylic resin obtained in Production Example 2, 6 parts by mass of polyfunctional urethane acrylate (manufactured by Mitsubishi Chemical Corporation, brand name “Cicco UT-4332”, mass average molecular weight (Mw) 4,700), which is an energy ray-curable compound. , 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, and diluted with an organic solvent. An adhesive composition was prepared.

(5) Manufacturing of adhesive sheets

The composition for forming a buffer layer obtained above was applied to one side of the substrate shown above so that the thickness of the buffer layer formed was 20 ㎛, and then ultraviolet rays were applied under the conditions of an illuminance of 30 mW/cm ² and an irradiation amount of 60 mJ/cm ² The composition for forming a buffer layer was semi-cured by irradiation, and a layer in which the composition for forming a buffer layer was semi-cured was formed on one side of the substrate.

Additionally, the composition for forming a surface coat layer obtained above was applied to the release treated surface of the release sheet (manufactured by Lintech Co., Ltd., brand name “SP-PET381031”) with a mayor bar so that the thickness of the surface coat layer formed was 2 μm. , and dried by heating to form a composition layer for forming a surface coat layer on the release sheet.

After bonding the composition layer for forming a surface coat layer on the release sheet and the semi-cured layer of the composition for forming a buffer layer formed on one side of the substrate, conditions of irradiance of 160 mW/cm ² and irradiation of 500 mJ/cm ² By irradiating ultraviolet rays, the composition for forming a buffer layer and the composition for forming a surface coat layer were cured, thereby obtaining a laminate having the buffer layer and the surface coat layer in this order on one side 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 with an adhesive layer is attached to the side of the base material of the laminate on which the buffer layer is not formed, thereby having a release sheet on both sides and forming a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order. A pressure-sensitive adhesive sheet was obtained.

Table 1 shows the evaluation results of the adhesive sheets obtained in each Example and Comparative Example.

S2104: Hydrogenated styrene-based thermoplastic elastomer (SEPS), styrene content: 65% by mass, manufactured by Kuraray Co., Ltd., product name “Septon (registered trademark) 2104”

・H1043: Hydrogenated styrene-based thermoplastic elastomer (SEBS), styrene content: 67% by mass, manufactured by Asahi Chemical Co., Ltd., product name “Toughtech (registered trademark) H1043”

S2006: Hydrogenated styrene-based thermoplastic elastomer (SEPS), styrene content: 35% by mass, manufactured by Kuraray Co., Ltd., product name “Septon (registered trademark) 2006”

・PMA-L: Propylene-butene-maleic anhydride copolymer, maleic anhydride modification ratio: 1.5% by mass, mass average molecular weight (Mw): 75,000, manufactured by Toyobo Co., Ltd., product name “Toyotaek (registered trademark) PMA-L” 」

Energy ray polymerizable multifunctional compound: mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate, manufactured by Nippon Gunpowder Co., Ltd., brand name “KAYARAD DPHA”

· Photopolymerization initiator: 2-hydroxy-2-methyl-1-phenylpropanone, IGM Resins B.V. Manufactured, brand name “Omnirad1173”

·Hydrophobic silica: Hydrophobized amorphous precipitated silica

From Table 1, it can be seen that the adhesive sheets of Examples 1 to 4, which satisfy the configuration of the adhesive sheet of this embodiment, are excellent in transportability after work processing. Additionally, whitening did not occur in the adhesive sheets of Examples 1 to 4 after heating. On the other hand, the adhesive sheets of Comparative Examples 1 and 2, which did not meet the configuration of the adhesive sheet of this embodiment, were inferior in transportability after work processing, and whitening occurred in the adhesive sheet after heating.

Claims (11)

It has a surface coat layer, a buffer layer, a base material, and an adhesive layer in this order,
The surface coat layer contains a styrene-based resin,
An adhesive sheet for semiconductor processing, wherein the content of structural units derived from a styrene-based compound in the styrene-based resin is 50% by mass or more. According to claim 1,
An adhesive sheet for semiconductor processing, wherein the content of structural units derived from a styrene-based compound in the styrene-based resin is 80% by mass or less. The method of claim 1 or 2,
The styrene-based resin is styrene-butadiene block copolymer, styrene-ethylene-propylene block copolymer, styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer, styrene-ethylene-butylene-styrene block copolymer. An adhesive sheet for semiconductor processing, which is at least one selected from the group consisting of polymers and styrene-ethylene-propylene-styrene block copolymers. The method of claim 1 or 2,
An adhesive sheet for semiconductor processing, wherein the mass average molecular weight (Mw) of the styrene-based resin is 10,000 to 600,000. The method of claim 1 or 2,
An adhesive sheet for semiconductor processing, wherein the surface coat layer has a thickness of 0.05 to 10 μm. The method of claim 1 or 2,
An adhesive sheet for semiconductor processing, wherein the buffer layer is a layer formed from a composition for forming a buffer layer containing urethane (meth)acrylate. The method of claim 1 or 2,
Adhesive sheet for semiconductor processing, used for backside grinding of semiconductor wafers. A step of attaching the adhesive sheet for semiconductor processing according to claim 1 or 2 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. 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 sticking process in which the adhesive sheet for semiconductor processing according to claim 1 or 2 is attached to the surface of the semiconductor wafer using the adhesive layer as a sticking surface after the step a, or before or after the step b. class,
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 the groove or the modified region is used as a starting point to form a plurality of semiconductor chips. A method of manufacturing a semiconductor device comprising grinding, grinding, and segmentation processes. 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 storage modulus E' of the surface coat layer at 90°C is 100 MPa or more. 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 difference between the haze value after heat treatment under the following conditions and the haze value before the heat treatment (haze value after heat treatment - haze value before heat treatment) is 2.0% or less.
(Conditions of heat treatment)
A metal plate (1) having a polished surface is placed on a hot plate whose temperature is maintained at 90°C with the polished surface facing upward, and a release sheet is applied to the adhesive layer on the polished surface of the metal plate (1). The attached adhesive sheet for semiconductor processing is placed in the direction in which the surface coat layer is on the polished surface side, and on the release sheet of the adhesive sheet for semiconductor processing, a metal plate having a polished surface on the side in contact with the release sheet ( 2) The adhesive sheet for semiconductor processing is heat-treated at 90°C for 1 minute by laminating the weight and the weight in this order.
The adhesive sheet for semiconductor processing used in the heat treatment has a rectangular shape in plan view and a size of 5 cm × 5 cm in plan view, and both the metal plate 1 and the metal plate 2 are made of SUS304. First, the shape in the plan view is rectangular, the size in the plan view is 7 cm The weight is assumed to have a circular cylindrical shape with a weight of 1 kg and a bottom diameter of 4 cm. The metal plate (1), the adhesive sheet for semiconductor processing, and the metal plate (2) are placed so that their four sides are parallel to each other, and the metal plate (1), the adhesive sheet for semiconductor processing, the metal plate (2), and the weight are , the positions of each center point as seen from the plane are arranged so that they coincide.