CN119614087A - Adhesive sheet for workpiece processing, method for producing the same, and method for producing electronic device - Google Patents

Abstract

The invention provides a bonding sheet for workpiece processing, which has excellent productivity and suppresses the adhesion of grinding dust, a manufacturing method thereof, and a manufacturing method of an electronic device using the bonding sheet for workpiece processing. The solution of the present invention is a pressure-sensitive adhesive sheet for work processing, which comprises, in order, a surface coating layer, a buffer layer, a base material, and a pressure-sensitive adhesive layer, and in which the static contact angle of diiodomethane at 23 ℃ with respect to the surface coating layer is 43 DEG or more, a method for producing the pressure-sensitive adhesive sheet, and a method for producing an electronic device using the pressure-sensitive adhesive sheet for work processing.

Description

Adhesive sheet for work processing, method for producing same, and method for producing electronic device

Technical Field

The present invention relates to an adhesive sheet for processing a workpiece, a method for producing the same, and a method for producing an electronic device.

Background

In the course of rapid progress in thinning, miniaturization, and multifunction of information terminal equipment, there is also a demand for thinning and densification of electronic device devices such as semiconductor devices mounted on these equipment.

As a method for thinning an electronic device, a method of grinding the back surface of a workpiece such as a semiconductor wafer used in the electronic device has been performed. The back grinding of the workpiece is performed in a state in which a workpiece processing adhesive sheet for back grinding (hereinafter, also referred to as "back grinding sheet") is attached to the surface of the workpiece, and the surface of the workpiece is protected by the sheet. The backgrinding plate may be peeled off from the surface of the workpiece after back grinding.

In recent years, as a grinding and singulation method for thinning a workpiece while suppressing damage to the workpiece, a prior art cutting method, a stealth prior art cutting method, or the like has been put into practical use. The dicing method is a method in which, after a groove of a predetermined depth is formed in the surface of a workpiece by a dicing blade or the like, the workpiece is ground from the back surface side until the groove is reached, and the workpiece is singulated. In the stealth dicing method, after a modified region is formed in a workpiece by irradiation of laser light, the workpiece is ground from the back side, and the modified region is cut by using the modified region as a start point of division, whereby the semiconductor chips are singulated. Back grinding sheets for protecting the surface of the workpiece are also used in these methods.

When grinding the back surface of a workpiece, a back grinding sheet attached to the workpiece is fixed to a surface (hereinafter, also referred to as "back surface") opposite to the surface attached to the workpiece by a support device such as a chuck table. Further, the back surface of the workpiece fixed to the table of the support device via the back grinding plate is ground while cooling water for removing heat and grinding dust generated by grinding is supplied to the grinding surface.

When back grinding is performed, if there is a chip between the back grinding plate and the table of the supporting device, cracks may occur in the workpiece or the workpiece monolithic product from an impact when the workpiece is fixed to the table, pressurization and vibration during back grinding, or the like, with the portion where the chip is present as a starting point. Since the chips adhere to the back surface of the back grinding sheet in a state of being contained in the cooling water, it is necessary to reduce the amount of the chips adhering to the back surface of the back grinding sheet in order to suppress the occurrence of the cracks.

Patent document 1 discloses, as an adhesive sheet for semiconductor processing having a reduced amount of adhering abrasive dust and excellent handling properties, an adhesive sheet for semiconductor processing having a surface coating layer, a buffer layer, a base material, and an adhesive layer in this order, wherein the surface coating layer is a layer formed from a composition for forming a surface coating layer containing an organosilicon compound.

Prior art literature

Patent literature

Patent document 1 Japanese patent laid-open No. 2023-048103

Disclosure of Invention

Problems to be solved by the invention

The adhesive sheet for semiconductor processing of patent document 1 can suppress adhesion of the grinding dust by providing a surface coating layer on one surface.

The surface coating layer can be formed by a method of applying a solution of an active ingredient dissolved in an organic solvent to a given member and then drying the solution, and in order to improve productivity of the adhesive sheet for work processing, it is desirable to increase a drying temperature for removing the organic solvent and shorten a drying time. However, according to the studies by the present inventors, it was found that the adhesion amount of the grinding dust could not be sufficiently suppressed if the drying temperature for removing the organic solvent was increased at the time of forming the surface coating layer. Therefore, it is difficult to improve the productivity of the adhesive sheet for workpiece processing, which can sufficiently suppress the adhesion amount of the grinding dust.

The present invention has been made in view of the above-described background, and an object thereof is to provide a pressure-sensitive adhesive sheet for workpiece processing, which is excellent in productivity and suppresses the adhesion amount of grinding dust, a method for producing the same, and a method for producing an electronic device using the pressure-sensitive adhesive sheet for workpiece processing.

Means for solving the problems

The present inventors have conducted intensive studies and as a result, have found that the above problems can be solved by a pressure-sensitive adhesive sheet for work processing having a surface coating layer, a buffer layer, a substrate and a pressure-sensitive adhesive layer in this order, the surface coating layer having a static contact angle of diiodomethane at 23 ℃ of 43 ° or more, and have completed the present invention as described below.

Namely, the present invention relates to the following [1] to [10].

[1] An adhesive sheet for processing a workpiece, comprising, in order, a surface coating layer, a buffer layer, a base material, and an adhesive layer,

The diiodomethane has a static contact angle of 43 ℃ or more at 23 ℃ with respect to the surface coating layer.

[2] The adhesive sheet for workpiece processing according to the above [1], wherein,

The surface coating layer is an organic layer containing a resin component.

[3] The adhesive sheet for workpiece processing according to the above [2], wherein,

The resin component is a polymer of a compound having 1 or more ethylenically unsaturated bonds.

[4] The adhesive sheet for workpiece processing according to the above [3], wherein,

The compound having 1 or more ethylenically unsaturated bonds is a styrene compound.

[5] The adhesive sheet for processing a workpiece according to any one of the above [1] to [4], wherein,

The thickness of the surface coating layer is 0.05-10 μm.

[6] The adhesive sheet for processing a workpiece according to any one of the above [1] to [5], 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 workpiece processing according to any one of the above [1] to [6], which is used for grinding a workpiece.

[8] A method for producing the adhesive sheet for workpiece processing described in any one of [2] to [4], comprising:

And a step of forming the surface coating layer by irradiating an energy ray to a composition for forming a surface coating layer containing the resin component, the energy ray-polymerizable polyfunctional compound and the photopolymerization initiator.

[9] A method of manufacturing an electronic device apparatus, the method comprising:

The process of adhering the adhesive sheet for workpiece processing described in any one of the above [1] to [7] to the surface of a workpiece with the adhesive layer as an adhering face, and

And grinding the back surface of the workpiece in a state where the surface coating layer side of the adhesive sheet for workpiece processing attached to the workpiece is fixed by a supporting means.

[10] A method of manufacturing an electronic device apparatus, the method comprising:

a dividing scheduled line forming step of forming a groove on the surface of a workpiece or a step of forming a modified region in the workpiece from the surface or the back of the workpiece;

A sheet adhering step of adhering the adhesive sheet for processing a workpiece according to any one of the above [1] to [7] to the surface of the workpiece with the adhesive layer as an adhering surface after the step a or before or after the step b, and

And grinding and singulating the back surface of the workpiece by grinding the back surface of the workpiece in a state in which the surface coating layer side of the adhesive sheet for workpiece processing attached to the workpiece is fixed by a supporting means, and singulating the workpiece into a plurality of workpiece singulated products using the grooves or the modified regions as starting points.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a pressure-sensitive adhesive sheet for workpiece processing which is excellent in productivity and suppresses the adhesion amount of grinding dust, and a method for manufacturing an electronic device using the pressure-sensitive adhesive sheet for workpiece processing.

Detailed Description

In the present specification, the lower limit value and the upper limit value described in layers may be independently combined with each other with respect to a preferable numerical range. For example, according to the description of "preferably 10 to 90, more preferably 30 to 60", the "preferably lower limit value (10)" and the "more preferably upper limit value (60)" may be combined to obtain "10 to 60".

In the present specification, the term "active ingredient" refers to a component other than a diluent solvent among components contained in a composition to be subjected to the formulation.

In the present specification, "(meth) acrylic acid" means both "acrylic acid" and "methacrylic acid", for example, and other similar expressions are also used.

In the present specification, the term "energy ray" means a ray having energy in an electromagnetic wave or a charged particle beam, and examples thereof include ultraviolet rays, radiation rays, and electron beams. For example, an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, or the like may be used as an ultraviolet light source to irradiate ultraviolet rays. As for the electron beam, an electron beam generated by an electron beam accelerator or the like may be irradiated.

In the present specification, "energy ray polymerizability" means a property of polymerization by irradiation with energy rays. The term "energy ray curability" refers to a property that is cured by irradiation with energy rays, and the term "non-energy ray curability" refers to a property that is not energy ray curable.

In the present specification, the "work" refers to a plate-like body formed by bonding the adhesive sheet for work processing of the present embodiment and then processing the same.

Examples of the work include a wafer, a panel-level package, a tape (long substrate) sealed with a molding resin, and the like, and among them, a wafer is preferable from the viewpoint of easy achievement of the effect of the present invention.

The wafer may be, for example, a semiconductor wafer such as a silicon wafer, a gallium arsenide wafer, a silicon carbide wafer, a gallium nitride wafer, or an indium phosphorus wafer, or an insulator wafer such as a glass wafer, a lithium tantalate wafer, or a lithium niobate wafer. In addition, a reconstituted wafer formed of a resin and a semiconductor for fabrication of a fan-out package or the like may be used. Among them, from the viewpoint of easily obtaining the effects of the present invention, the wafer is preferably a semiconductor wafer or an insulator wafer, more preferably a semiconductor wafer, and further preferably a silicon wafer.

Circuits such as wirings, capacitors, diodes, and transistors are generally formed on the surface of a semiconductor wafer. These circuits can be formed by a conventionally known method such as an etching method or a Lift-Off (Lift-Off) method.

The thickness of the workpiece before processing is not particularly limited, and is usually 500 to 1000 μm.

In the present specification, the term "workpiece singulated" refers to an object obtained by dividing a workpiece. For example, in the case where the workpiece is a semiconductor wafer, the workpiece singulated is a semiconductor chip, and in the case where the workpiece is a tape (elongated substrate) subjected to panel-level packaging or molded resin sealing, the workpiece singulated is a semiconductor package.

In the present specification, the "electronic device" includes, for example, a workpiece singulated product, an electronic component including the workpiece singulated product, and an electronic apparatus including the electronic component.

In the present specification, the "front surface" of the workpiece means a surface on which a circuit is formed, and the "back surface" means a surface on which a circuit is not formed.

The mechanism of action described in the present specification is presumed, and the mechanism for achieving the effect of the adhesive sheet for workpiece processing of the present invention is not limited.

[ Adhesive sheet for workpiece processing ]

The adhesive sheet for workpiece processing (hereinafter also referred to as "adhesive sheet") of the present embodiment is an adhesive sheet for workpiece processing, which has a surface coating layer, a buffer layer, a base material, and an adhesive layer in this order, and has a static contact angle of diiodomethane at 23 ℃ with respect to the surface coating layer of 43 ℃ or more.

The adhesive sheet of the present embodiment is adhered to the surface of a workpiece, and is used for performing a predetermined process on the workpiece while protecting the surface. After a given process is performed on the workpiece, the adhesive sheet of the present embodiment is peeled off and removed from the workpiece.

The pressure-sensitive adhesive sheet of the present embodiment may have layers other than the surface coating layer, the buffer layer, the base material, and the pressure-sensitive adhesive layer, or may not have these layers. Examples of the layer other than the surface coating layer, the buffer layer, the substrate and the pressure-sensitive adhesive layer include an intermediate layer provided between the substrate and the pressure-sensitive adhesive layer, and a release sheet provided on the side of the pressure-sensitive adhesive layer opposite to the substrate.

The following describes the respective members constituting the pressure-sensitive adhesive sheet of the present embodiment in order.

< Surface coating layer >

The surface coating layer is a layer provided on the opposite side of the buffer layer from the base material, and is fixed by the supporting device when the work is processed.

(Contact angle of diiodomethane of surface coating layer)

The diiodomethane layer of the pressure-sensitive adhesive sheet of the present embodiment has a static contact angle (hereinafter also simply referred to as "diiodomethane contact angle") of 43 ° or more at 23 ℃ with respect to the surface coating layer.

When the diiodomethane contact angle of the surface coating layer is 43 ° or more, the adhesion amount of the grinding dust can be sufficiently suppressed even if the drying temperature for removing the organic solvent is increased at the time of forming the surface coating layer, and therefore, the adhesive sheet of the present embodiment is excellent in productivity and the adhesion amount of the grinding dust can be suppressed.

The diiodomethane contact angle of the surface coating layer is preferably 45 ° or more, more preferably 48 ° or more, and still more preferably 50 ° or more, from the viewpoint of further reducing the adhesion amount of the chips.

The upper limit of the diiodomethane contact angle of the surface coating layer is not particularly limited, and may be, for example, 70 ° or less, 60 ° or less, or 55 ° or less from the viewpoint of ease of production.

The diiodomethane contact angle of the surface coating layer was a value measured in accordance with JIS R3257:1999, and specifically, it was measured by the method described in examples.

The surface coating layer of the pressure-sensitive adhesive sheet of the present embodiment may be an inorganic layer or an organic layer, and is preferably an organic layer, more preferably an organic layer containing a resin component, from the viewpoints of productivity and handling properties of the pressure-sensitive adhesive sheet.

(Resin component)

The resin component is preferably a thermoplastic resin from the viewpoint of reducing the amount of the adhering chips.

The resin component may be used alone or in combination of two or more.

[ Thermoplastic resin ]

The thermoplastic resin is preferably a polymer of a compound having 1 or more ethylenically unsaturated bonds (hereinafter, also referred to as "polymer (1)") from the viewpoint of further reducing the amount of adhering chips.

In the present embodiment, "ethylenically unsaturated bond" means a carbon-carbon double bond capable of undergoing an addition reaction, and a double bond of an aromatic ring is not included therein.

The content of the structural unit derived from the compound having 1 or more ethylenically unsaturated bonds in the polymer (1) is not particularly limited, but is preferably 70% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more. When the content of the structural unit derived from the compound having 1 or more ethylenically unsaturated bonds is equal to or greater than the lower limit, the amount of the attached abrasive grains tends to be further reduced.

The content of the structural unit derived from the compound having 1 or more ethylenically unsaturated bonds in the polymer (1) may be 100 mass%, but may be 99.5 mass% or less or 99 mass% or less, for example, in order to contain the structural unit derived from another monomer.

Examples of the compound having 1 or more ethylenically unsaturated bonds include styrene compounds such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, chlorostyrene, and methoxystyrene; chain monoolefins such as ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene and the like; 1, 4-hexadiene, 4-methyl-1, 4-hexadiene, 5-methyl-1, 4-hexadiene and other chain nonconjugated dienes (nonconjugated dienes), 1, 3-butadiene, isoprene, 1, 3-pentadiene, 2, 3-dimethyl-1, 3-butadiene, 2-phenyl-1, 3-butadiene, 1, 3-hexadiene and other conjugated dienes (conjugated dienes), cyclic mono-olefins such as cyclobutene, cyclopentene, methylcyclopentene, cyclohexene, methylcyclohexene, cycloheptene, cyclooctene and other cyclic dienes such as cyclohexadiene, methylcyclohexadiene, cyclooctadiene, methylcyclooctadiene and phenylcyclooctadiene, norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, tetracyclododecene, tetracyclo [7.4.0.1 ^10,13.0^2,7 ] tridec-2,4,6,11-tetraene and other polycyclic olefins, monomers having an oxygen atom and an ethylenically unsaturated bond such as maleic anhydride and vinyl acetate, maleimide compounds, and monomers having a nitrogen atom and an ethylenically unsaturated bond such as nitrile monomers.

In the above options, the polymer (1) preferably contains a structural unit derived from a styrenic compound. Hereinafter, the polymer (1) containing a structural unit derived from a styrene compound is referred to as "styrene resin".

The content of the structural unit derived from the styrene compound in the styrene resin is not particularly limited, but is preferably 50% by mass or more, more preferably 55% by mass or more, and still more preferably 60% by mass or more.

When the content of the structural unit derived from the styrene compound in the styrene resin is equal to or higher than the lower limit, the heat resistance of the surface coating layer tends to be good.

The content of the structural unit derived from the styrene compound in the styrene resin is not particularly limited, but is preferably 80% by mass or less, more preferably 75% by mass or less, and still more preferably 70% by mass or less.

When the content of the structural unit derived from the styrene compound in the styrene resin is equal to or less than the upper limit, the balance between the amount of adhering grinding dust and heat resistance tends to be easily improved by introducing the structural unit other than the structural unit derived from the styrene compound.

Examples of the structural unit other than the structural unit derived from a styrene compound that may be contained in the styrene resin include structural units derived from a compound other than a styrene compound, which are exemplified as the above-mentioned compounds having 1 or more ethylenically unsaturated bonds. Of these, the styrene-based resin more preferably contains a structural unit derived from a conjugated diene.

The structural unit derived from the conjugated diene means a structural unit formed by addition polymerization of the conjugated diene, a structural unit formed by hydrogenation of a structural unit formed by addition polymerization of the conjugated diene, and the like.

Examples of the structural unit formed by hydrogenating the structural unit formed by addition polymerization of the conjugated diene include an ethylene-propylene unit formed by hydrogenating a structural unit formed by addition polymerization of isoprene, an ethylene-butene unit formed by hydrogenating a structural unit formed by addition polymerization of 1, 3-butadiene, and the like.

When the styrene resin contains a structural unit derived from a conjugated diene, the content thereof in the styrene resin is not particularly limited, but is preferably 20 to 50% by mass, more preferably 25 to 45% by mass, and still more preferably 30 to 40% by mass.

When the content of the conjugated diene-derived structural unit in the styrene-based resin is equal to or greater than the lower limit, the amount of the adhering chips tends to be further reduced. In addition, when the content of the conjugated diene-derived structural unit in the styrene-based resin is equal to or less than the upper limit, the handling property after the work processing tends to be good.

The styrene-based resin is preferably one or more selected from the group consisting of styrene-butadiene block copolymers, styrene-ethylene-propylene block copolymers, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene-butylene-styrene block copolymers (hereinafter also referred to as "SEBS") and styrene-ethylene-propylene-styrene block copolymers (hereinafter also referred to as "SEPS") from the viewpoint of the amount of adhering chips and heat resistance, and more preferably one or more selected from the group consisting of styrene-ethylene-butylene-styrene block copolymers and styrene-ethylene-propylene-styrene block copolymers.

Examples of the polymer (1) other than the styrene resin include homopolymers such as polyethylene, polypropylene and polybutadiene, and binary copolymers such as ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer, ethylene-tetracyclododecene copolymer, propylene-butene copolymer, 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-vinyl acetate copolymer, ethylene-maleic anhydride copolymer, ethylene-butene-vinyl acetate copolymer and ethylene-butene-vinyl acetate copolymer, propylene-butene- (meth) acrylate copolymers, and the like.

The weight average molecular weight (Mw) of the thermoplastic resin 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.

When the weight average molecular weight (Mw) of the thermoplastic resin is not less than the lower limit, the handling properties after processing the workpiece tend to be more excellent. When the weight average molecular weight (Mw) of the thermoplastic resin is equal to or less than the upper limit, the solvent solubility of the thermoplastic resin is improved, and the formation of a surface coating layer by coating tends to be easy.

In the present embodiment, the weight average molecular weight (Mw) is a value in terms of standard polystyrene measured by Gel Permeation Chromatography (GPC), and specifically, is a value measured by the method described in examples.

The content of the resin component in the surface coating layer is not particularly limited, but is preferably 30 to 80% by mass, more preferably 40 to 70% by mass, still more preferably 45 to 60% by mass, relative to the total amount (100% by mass) of the surface coating layer

When the content of the resin component is within the above range, the adhesion amount of the chips tends to be further reduced.

(Subjected to hydrophobization) treated silica

The surface coating layer preferably further contains a hydrophobicized silica in addition to the resin component.

When the surface coating layer contains the hydrophobized silica, the amount of adhering chips in the adhesive sheet of the present embodiment tends to be further reduced.

The hydrophobicized silica may be used alone or in combination of two or more.

Examples of the hydrophobicized silica include a silica obtained by surface-treating a raw silica with a hydrophobicizing agent.

The raw material silica to be subjected to hydrophobization may be, for example, wet-process silica produced by a wet process such as a precipitation process, a gel process, or a sol-gel process, or may be dry-process silica such as fumed silica or fused silica. Among them, wet-process silica is preferred, and precipitation-process silica is more preferred, from the viewpoint of ease of hydrophobization.

Examples of the hydrophobizing agent include organosilicon compounds, fatty acids, fatty acid metal salts, and the like.

The hydrophobizing agent may be used alone or in combination of two or more.

Examples of the method for surface-treating the raw silica with the hydrophobizing agent include a method in which the raw silica is brought into contact with the hydrophobizing agent in a solvent, a method in which vapor of the hydrophobizing agent carried by carrier gas such as nitrogen is brought into contact with the raw silica, and a method in which a stock solution of the hydrophobizing agent is brought into direct contact with the raw silica.

The shape of the hydrophobicized silica is not particularly limited, and examples thereof include spherical and irregular shapes. Among them, the irregular shape is preferable from the viewpoint of further reducing the amount of the adhering abrasive dust.

Examples of the hydrophobicized silica include "AEROSIL (registered trademark) series" manufactured by Evonik corporation, "QSG series" manufactured by singer chemical industry corporation, "Nipsil (registered trademark) SS series" manufactured by eastern Cao Guihua corporation, and "SYLOPHOBIC (registered trademark) series" manufactured by Fuji SILYSIA CHEMICAL corporation.

When the surface coating layer contains the hydrophobicized silica, the content of the hydrophobicized silica in the surface coating layer is not particularly limited, but is preferably 1 to 150 parts by mass, more preferably 10 to 120 parts by mass, still more preferably 30 to 90 parts by mass, and still more preferably 50 to 70 parts by mass, based on 100 parts by mass of the resin component.

When the content of the hydrophobized silica is not less than the lower limit, the amount of adhering chips tends to be further reduced. When the content of the hydrophobicized silica is not more than the upper limit, the film forming property of the surface coating layer tends to be improved.

The surface coating layer may contain components other than the resin component and the hydrophobicized silica.

For example, from the viewpoint of further improving adhesion to the buffer layer, the surface coating layer is preferably a layer formed by irradiating a composition containing a resin component and containing an energy ray polymerizable polyfunctional compound and a photopolymerization initiator with energy rays.

In the following description, the composition for forming a surface coating layer may be referred to as a "composition for forming a surface coating layer".

(Energy ray polymerizable multifunctional Compound)

The energy ray polymerizable polyfunctional compound is a compound having 2 or more energy ray polymerizable functional groups.

The energy ray polymerizable polyfunctional compound may be used singly or in combination of two or more.

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

The energy ray polymerizable functional group of the energy ray polymerizable polyfunctional compound is preferably a (meth) acryl group.

The energy ray polymerizable polyfunctional compound is preferably a polyfunctional (meth) acrylate monomer.

Examples of the polyfunctional (meth) acrylate monomer include 2-functional (meth) acrylate monomers such as 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, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified phosphoric acid di (meth) acrylate, di (acryloyloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, and isocyanuric acid ethylene oxide-modified diacrylate, 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, tri (acryloyloxyethyl) isocyanurate, bis (acryloyloxyethyl) hydroxyethyl isocyanurate, ethylene oxide-modified triacrylate, epsilon-caprolactone-modified tri (acryloyloxyethyl) isocyanurate, tetra (meth) acrylate, pentaerythritol di (meth) acrylate, tetra (meth) acrylate, and the like, propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate, and the like. Among them, dipentaerythritol hexa (meth) acrylate and dipentaerythritol penta (meth) acrylate are preferable, and dipentaerythritol hexa-acrylate and dipentaerythritol penta-acrylate are more preferable.

When the composition for forming a surface coating layer contains an energy ray-polymerizable polyfunctional compound, the content of the energy ray-polymerizable polyfunctional compound is preferably 10 to 60 parts by mass, more preferably 15 to 50 parts by mass, and still more preferably 20 to 40 parts by mass, per 100 parts by mass of the resin component.

When the content of the energy ray polymerizable polyfunctional compound is not less than the lower limit, the adhesion between the surface coating layer and the buffer layer tends to be excellent. When the content of the energy ray-polymerizable polyfunctional compound is not more than the upper limit, the balance between adhesion to the buffer layer and the amount of adhering chips tends to be easily improved.

(Photopolymerization initiator)

Examples of the photopolymerization initiator include a photosensitizer such as benzoin compound, acetophenone compound, acylphosphine oxide compound, titanocene compound, thioxanthone compound, peroxide compound, amine, quinone, etc., and more specifically, examples thereof include 2, 2-dimethoxy-2-phenylacetophenone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropane-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropanoyl) benzyl ] phenyl } -2-methylpropan-1-one, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, butanedione, 8-chloroanthraquinone, phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide, etc. Among them, 2-dimethoxy-2-phenylacetophenone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropane-1-one, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropanoyl) benzyl ] phenyl } -2-methylpropan-1-one are preferable from the viewpoint of improving productivity of the adhesive sheet for work processing capable of sufficiently suppressing the adhesion amount of the shavings.

The photopolymerization initiator may be used alone or in combination of two or more.

The molecular weight of the photopolymerization initiator is preferably 255 or more, more preferably 260 or more, further preferably 265 or more, particularly preferably 270 or more.

When the molecular weight of the photopolymerization initiator is equal to or greater than the lower limit, the diiodomethane contact angle of the surface coating layer to be formed tends to be 43 ° or more, and the adhesive sheet of the present embodiment tends to be an adhesive sheet in which the adhesion amount of the grinding dust is suppressed.

The molecular weight of the photopolymerization initiator is preferably 400 or less, more preferably 380 or less, and further preferably 360 or less.

When the molecular weight of the photopolymerization initiator is not more than the above upper limit, the solvent solubility of the photopolymerization initiator is improved, and the composition for forming a surface coating layer can be easily prepared.

When the composition for forming a surface coating layer contains a photopolymerization initiator, the content thereof is not particularly limited, but is preferably 0.01 to 40 parts by mass, more preferably 0.1 to 30 parts by mass, still more preferably 1 to 20 parts by mass, and particularly preferably 5 to 10 parts by mass, relative to 100 parts by mass of the energy ray polymerizable polyfunctional compound, from the viewpoint of homogenizing and sufficiently conducting the energy ray polymerization reaction.

(Other Components)

The surface coating layer may contain other components than those described above within a range that does not impair the effects of the present invention. Examples of the other components include resins other than those mentioned above, antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, dyes and other additives.

(Thickness of surface coating layer)

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

When the thickness of the surface coating layer is equal to or greater than the lower limit, a uniform layer can be formed, and the amount of adhering chips can be further reduced. When the thickness of the surface coating layer is equal to or less than the upper limit, the effect of absorbing the irregularities such as foreign matter on the chuck table by the buffer layer tends to be easily obtained.

< Buffer layer >

The buffer layer is a layer provided between the substrate and the surface coating layer, and serves to absorb vibration, impact, and the like generated during back grinding and prevent cracking of the workpiece. Further, by providing the buffer layer, it is possible to absorb irregularities such as foreign matter present on the table of the supporting device, and to improve the holding property of the supporting device with respect to the adhesive sheet.

(Composition for Forming buffer layer)

The buffer layer may be formed from a buffer layer forming composition.

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 from the viewpoint of obtaining physical properties suitable for the buffer layer.

The composition for forming a buffer layer preferably contains a urethane (meth) acrylate (a 1) as the energy ray-polymerizable compound. By containing the urethane (meth) acrylate (a 1) in the composition for forming a buffer layer, the storage modulus and the like of the buffer layer tend to be adjusted to a good range.

From the same viewpoint, the composition for forming a buffer layer preferably contains one or more kinds of polymerizable compounds (a 2) selected from alicyclic groups or heterocyclic groups having 6 to 20 ring-forming atoms and polymerizable compounds (a 3) having functional groups in addition to the urethane (meth) acrylate (a 1), and more preferably contains the polymerizable compounds (a 2) having the alicyclic groups or heterocyclic groups having 6 to 20 ring-forming atoms and the polymerizable compounds (a 3) having functional groups in addition to the urethane (meth) acrylate (a 1).

In the present specification, the number of ring-forming atoms refers to the number of atoms constituting the ring itself in a compound having a structure in which atoms are bonded in a ring, and atoms not constituting the ring (for example, hydrogen atoms bonded to atoms constituting the ring) and atoms contained in a substituent in the case where the ring is substituted with a substituent are not included in the number of ring-forming atoms.

[ Urethane (meth) acrylate (a 1) ]

The urethane (meth) acrylate (a 1) is a compound having a (meth) acryloyl group and a urethane bond, and has a property of polymerizing by irradiation with energy rays.

The urethane (meth) acrylate (a 1) may be used singly or in combination of two or more.

The weight average molecular weight (Mw) of the urethane (meth) acrylate (a 1) 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 in 1 molecule of the urethane (meth) acrylate (a 1) is not particularly limited, but is preferably 1 to 4, more preferably 1 to 3, still more preferably 1 or 2.

The urethane (meth) acrylate (a 1) can be obtained, for example, by reacting a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound with a polyisocyanate compound with a (meth) acrylate having a hydroxyl group.

The polyol compound is not particularly limited as long as it has 2 or more hydroxyl groups.

Specific examples of the polyol compound include alkylene glycol, polyether polyol, polyester polyol, and polycarbonate polyol. Among them, polyester polyols are preferable.

The polyol compound may be any of 2-functional diol, 3-functional triol, and 4-functional or more polyol, and is preferably 2-functional diol, more preferably polyester diol.

The polyhydric alcohol compound may be used singly or in combination of two or more.

Examples of the polyisocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate and trimethylhexamethylene diisocyanate, alicyclic diisocyanates such as isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4, 4 '-diisocyanate, dicyclohexylmethane-2, 4' -diisocyanate and ω, ω '-diisocyanate dimethylcyclohexane, and aromatic diisocyanates such as 4,4' -diphenylmethane diisocyanate, toluene diisocyanate, xylylene diisocyanate, dimethylbiphenyl diisocyanate, tetramethylxylylene diisocyanate and naphthalene-1, 5-diisocyanate. Among them, isophorone diisocyanate, hexamethylene diisocyanate, xylylene diisocyanate are preferable.

The polyisocyanate compound may be used singly or in combination of two or more.

The (meth) acrylate having a hydroxyl group which reacts with the terminal isocyanate urethane prepolymer is not particularly limited as long as it is a compound having a hydroxyl group and a (meth) acryloyl group in at least 1 molecule.

Examples of the (meth) acrylic acid ester having a hydroxyl group include hydroxyl group-containing (meth) acrylamides such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 4-hydroxycyclohexyl (meth) acrylate, 5-hydroxycyclooctyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, and (meth) acrylic acid hydroxyalkyl esters such as N-methylol (meth) acrylamide, vinyl alcohol, vinyl phenol, and a reactant obtained by reacting (meth) acrylic acid with diglycidyl esters of bisphenol A. Among them, hydroxyalkyl (meth) acrylates are preferable, and 2-hydroxyethyl (meth) acrylate is more preferable.

The (meth) acrylic acid ester having a hydroxyl group may be used singly or in combination of two or more.

The conditions for reacting the terminal isocyanate urethane prepolymer with the (meth) acrylate having a hydroxyl group are not particularly limited, and may be, for example, conditions for reacting at 60 to 100 ℃ for 1 to 4 hours in the presence of an organic solvent, a catalyst or the like added as needed.

The content of the urethane (meth) acrylate (a 1) in the composition for forming a buffer layer is not particularly limited, but is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and still more preferably 30 to 50% by mass, based on the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer.

[ Polymerizable Compound (a 2) having an alicyclic group or heterocyclic group having 6 to 20 ring members ]

When the buffer layer-forming composition contains the polymerizable compound (a 2) having an alicyclic group or heterocyclic group having 6 to 20 ring-forming atoms (hereinafter, also referred to as "polymerizable compound (a 2) having an alicyclic group or heterocyclic group)"), the film-forming property of the buffer layer-forming composition tends to be improved.

Examples of the atoms forming the ring structure of the heterocyclic group include carbon atoms, nitrogen atoms, oxygen atoms, and sulfur atoms.

The polymerizable compound (a 2) having an alicyclic group or a heterocyclic group may be used singly or in combination of two or more.

The polymerizable compound (a 2) having an alicyclic group or a heterocyclic group is preferably a compound having a (meth) acryloyl group.

The number of (meth) acryloyl groups in 1 molecule of the polymerizable compound (a 2) having an alicyclic group or a heterocyclic group is not particularly limited, but is preferably 1 or more, more preferably 1 or 2, and further preferably 1.

The number of ring-forming atoms of the alicyclic group or heterocyclic group in the polymerizable compound (a 2) having an alicyclic group or heterocyclic group is 6 to 20, preferably 6 to 18, more preferably 6 to 16, and still more preferably 7 to 12.

Examples of the polymerizable compound (a 2) having an alicyclic group or heterocyclic group include alicyclic group-containing (meth) acrylates such as isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, adamantyl (meth) acrylate, and heterocyclic group-containing (meth) acrylates such as tetrahydrofurfuryl (meth) acrylate and morpholino (meth) acrylate. Among them, alicyclic group-containing (meth) acrylate is preferable, and isobornyl (meth) acrylate is more preferable.

The content of the polymerizable compound (a 2) having an alicyclic group or a heterocyclic group in the composition for forming a buffer layer is not particularly limited, but is preferably 10 to 70% by mass, more preferably 20 to 60% by mass, and still more preferably 30 to 50% by mass, based on the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer.

[ Polymerizable Compound (a 3) having functional group ]

By containing the polymerizable compound (a 3) having a functional group in the composition for forming a buffer layer, the viscosity of the composition for forming a buffer layer can be adjusted to a proper range.

The polymerizable compound (a 3) having a functional group may be used singly or in combination of two or more.

Examples of the functional group of the polymerizable compound (a 3) having a functional group include a hydroxyl group, an epoxy group, an amide group, and an amino group.

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

The polymerizable compound (a 3) having a functional group is preferably a compound having a functional group and a (meth) acryloyl group.

The number of (meth) acryloyl groups in 1 molecule of the polymerizable compound (a 3) having a functional group is not particularly limited, but is preferably 1 or more, more preferably 1 or 2, and still more preferably 1.

Examples of the polymerizable compound (a 3) 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 the hydroxyl group-containing polymerizable compound include hydroxyl group-containing (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, vinyl ether compounds such as hydroxyethyl vinyl ether and hydroxybutyl vinyl ether, and the like.

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

Examples of the amide group-containing polymerizable compound include (meth) acrylamide, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hydroxymethyl (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, and N-vinylformamide.

Examples of the amino group-containing polymerizable compound include amino group-containing (meth) acrylates such as primary amino group-containing (meth) acrylates, secondary amino group-containing (meth) acrylates, and tertiary amino group-containing (meth) acrylates.

Among these compounds, 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 functional group-containing polymerizable compound (a 3) in the composition for forming a buffer layer is not particularly limited, but is preferably 5 to 40% by mass, more preferably 10 to 30% by mass, and even more preferably 15 to 25% by mass, based on the total amount (100% by mass) of the active ingredients of the composition for forming a buffer layer.

[ Other polymerizable Compound ]

The composition for forming a buffer layer may contain other polymerizable compounds other than the components (a 1) to (a 3) within a range that does not impair the effects of the present invention.

Examples of the other polymerizable compound include alkyl (meth) acrylate having an alkyl group having 1 to 20 carbon atoms, vinyl compounds such as styrene, N-vinylpyrrolidone and N-vinylcaprolactam, and the like.

The other polymerizable compounds may be used alone or in combination of two or more.

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

[ 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 the energy ray irradiation amount by the energy ray irradiation.

The photopolymerization initiator may be used alone or in combination of two or more.

Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones, and more specifically, examples thereof include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, butanedione, 8-chloroanthraquinone, phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide, and the like. Among them, 1-hydroxycyclohexyl phenyl 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, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5 parts by mass, based on 100 parts by mass of the energy ray polymerizable compound, from the viewpoint of homogenizing and sufficiently conducting the energy ray curing reaction.

(Other Components)

The composition for forming a buffer layer may contain other components within a range that does not impair the effects of the present invention. Examples of the other components include resin components other than the above resins, antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, dyes, and other additives.

(Young's modulus of buffer layer)

The Young's modulus of the buffer layer at 23 ℃ is smaller than that of the substrate at 23 ℃, specifically, preferably lower than 1,200MPa, more preferably lower than 1,000MPa, and further preferably lower than 900MPa. The Young's modulus of the buffer layer at 23℃is preferably 50MPa or more, more preferably 100MPa or more.

When the Young's modulus of the cushion layer at 23℃is equal to or lower than the upper limit, the effect of absorbing vibration, impact, and the like generated during back grinding tends to be improved, and the holding property of the adhesive sheet tends to be improved. In addition, when the young's modulus of the buffer layer at 23 ℃ is equal to or higher than the lower limit value, the buffer layer tends to be prevented from being excessively deformed when the workpiece is processed.

The Young's modulus of the buffer layer at 23℃can be measured under the conditions of a test speed of 200 mm/min based on JIS K7127:1999.

(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%.

When the stress relaxation rate of the buffer layer is in the above range, the effect of absorbing vibration, impact, and the like generated at the time of back grinding and the holding property of the adhesive sheet tend to be improved.

The stress relaxation rate of the buffer layer was determined by cutting a buffer layer having a thickness of 200 μm into 15mm×140mm and using the values of stress A (N/m ²) when the test piece was stretched by 10% at 200 mm/min by grasping both ends of the test piece and stress B (N/m ²) after 1 minute from the stop of the stretching as test pieces.

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.

When the thickness of the buffer layer is equal to or greater than the lower limit, the effect of absorbing vibration, impact, and the like generated during back grinding and the holding property of the adhesive sheet tend to be improved. When the thickness of the buffer layer is equal to or less than the upper limit, excessive deformation of the buffer layer during processing of the workpiece tends to be suppressed.

< Adhesive layer >

The pressure-sensitive adhesive layer is a layer provided on the opposite side of the base material from the buffer layer, and is a layer to be adhered to a work.

The adhesive layer is preferably a layer formed of an energy ray curable adhesive. By forming the adhesive layer from an energy ray-curable adhesive, the surface of the workpiece can be well protected with sufficient adhesiveness before energy ray curing, and the peeling force can be reduced after energy ray curing, thereby achieving easy peeling from the workpiece.

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

X-type adhesive composition an energy ray-curable adhesive composition comprising a non-energy ray-curable adhesive resin (hereinafter also referred to as "adhesive resin I") and an energy ray-curable compound other than the adhesive resin

An adhesive composition having energy ray-curability, which contains an energy ray-curable adhesive resin (hereinafter also referred to as "adhesive resin II") having an unsaturated group introduced into a side chain of the non-energy ray-curable adhesive resin, and an energy ray-curable adhesive composition which does not contain an energy ray-curable compound other than the adhesive resin

An XY-type adhesive composition comprising the energy ray-curable adhesive resin II and an energy ray-curable compound other than the adhesive resin

Among them, the energy ray-curable adhesive is preferably an XY-type adhesive composition. By using an XY-type adhesive composition, there is a tendency that the adhesive composition has sufficient adhesiveness before curing and can sufficiently reduce the peeling force with respect to a work after curing.

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

Examples of the non-energy ray-curable adhesive include adhesives containing the adhesive resin I and not containing the adhesive resin II and the energy ray-curable compound.

Next, each component constituting the adhesive layer will be described in more detail.

In the following description, the term "adhesive resin" is used as a term meaning one or both of adhesive resin I and adhesive resin II. In the following description, the term "adhesive composition" is merely referred to as "adhesive composition", and is also intended to include the concepts of an X-type adhesive composition, a Y-type adhesive composition, an XY-type adhesive composition, and adhesive compositions other than these.

Examples of the adhesive resin include an acrylic resin, a urethane resin, a rubber resin, and a silicone resin. Among them, acrylic resins are preferable.

(Acrylic resin)

The acrylic resin preferably contains a structural unit derived from an alkyl (meth) acrylate.

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

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

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

The structural units derived from the alkyl (meth) acrylate having 4 or more carbon atoms in the alkyl group contained in the acrylic resin may be one kind or two or more kinds.

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

Examples of the alkyl (meth) acrylate having 4 or more carbon atoms as the alkyl group include butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, and the like. Of these, butyl (meth) acrylate is preferable, and butyl acrylate is more preferable.

When the acrylic resin contains a structural unit derived from a (meth) acrylic acid alkyl ester having 4 or more carbon atoms as an alkyl group, the content thereof in the acrylic resin is preferably 30 to 90% by mass, more preferably 40 to 80% by mass, and even more preferably 45 to 60% by mass, from the viewpoint of further improving the adhesive force of the adhesive layer.

From the viewpoint of improving the storage modulus G' and the adhesive property of the adhesive layer, the acrylic resin preferably contains a structural unit derived from an alkyl (meth) acrylate having 4 or more carbon atoms in the alkyl group and a structural unit derived from an alkyl (meth) acrylate having 1 to 3 carbon atoms in the alkyl group.

The structural units of the alkyl (meth) acrylate having 1 to 3 carbon atoms derived from the alkyl group contained in the acrylic resin may be one kind or two or more kinds.

Examples of the alkyl (meth) acrylate 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. Among them, methyl (meth) acrylate is preferable, ethyl (meth) acrylate is more preferable, methyl (meth) acrylate is more preferable, and methyl methacrylate is still more preferable.

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

The acrylic resin preferably further contains a structural unit derived from a functional group-containing monomer.

By incorporating structural units derived from functional group-containing monomers into the acrylic resin, functional groups that are the crosslinking start points of reaction with the crosslinking agent or functional groups that can react with unsaturated group-containing compounds to introduce unsaturated groups into the side chains of the acrylic resin can be introduced.

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

Examples of the functional group-containing monomer include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, and an epoxy group-containing monomer. Among them, hydroxyl group-containing monomers and carboxyl group-containing monomers are preferable, and hydroxyl group-containing monomers are more preferable.

Examples of the hydroxyl group-containing monomer include (meth) acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, butyl 2-hydroxy (meth) acrylate, butyl 3-hydroxy (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like, and unsaturated alcohols such as vinyl alcohol and allyl alcohol, and the like.

Examples of the carboxyl group-containing monomer include (meth) acrylic acid, an ethylenically unsaturated monocarboxylic acid such as crotonic acid, an ethylenically unsaturated dicarboxylic acid such as fumaric acid, itaconic acid, maleic acid, citraconic acid, and anhydrides thereof, 2-carboxyethyl methacrylate, and the like.

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

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

The structural units derived from the other monomers contained in the acrylic resin may be one kind alone or two or more kinds.

Examples of the other monomer include styrene, α -methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

In the acrylic resin, an unsaturated group having energy ray polymerizability may be further introduced to impart energy ray curability.

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

Examples of the unsaturated group included in the unsaturated group-containing compound include (meth) acryl, vinyl, and allyl. Among them, a (meth) acryl group is preferable.

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

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

When the acrylic resin containing the structural unit derived from the functional group-containing monomer is reacted with the unsaturated group-containing compound, the ratio of the functional groups to be reacted with the unsaturated group-containing compound in the total number of functional groups in the acrylic resin is not particularly limited, but is preferably 60 to 98 mol%, more preferably 70 to 95 mol%, still more preferably 80 to 93 mol%.

When the ratio of the functional group reactive with the unsaturated group-containing compound is within the above range, sufficient energy ray curability can be imparted to the acrylic resin, and the functional group that has not reacted with the unsaturated group-containing compound can be reacted with the crosslinking agent to crosslink the acrylic resin.

The weight average molecular weight (Mw) of the acrylic resin is not particularly limited, but is preferably 30 to 150 tens of thousands, more preferably 35 to 100 tens of thousands, and further preferably 40 to 60 tens of thousands.

When the weight average molecular weight (Mw) of the acrylic resin is in the above range, the adhesive force and cohesive force of the adhesive layer tend to be more excellent.

(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 having an unsaturated group in the molecule and curable by irradiation with energy rays.

Examples of the energy ray-curable compound include polyvalent (meth) acrylate monomers such as trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1, 4-butanediol di (meth) acrylate, and 1, 6-hexanediol di (meth) acrylate, and oligomers such as urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, and epoxy (meth) acrylate. Among them, urethane (meth) acrylate oligomer is preferable from the viewpoint of having a relatively high molecular weight and being less likely to cause a decrease in the elastic modulus of the 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 further preferably 600 to 6,000. In the case where the energy ray-curable compound is an oligomer, the molecular weight refers to a weight average molecular weight (Mw).

The content of the energy ray-curable compound in the X-type adhesive composition is not particularly limited, but is preferably 40 to 200 parts by mass, more preferably 50 to 150 parts by mass, and further preferably 60 to 90 parts by mass, relative to 100 parts by mass of the adhesive resin.

When the content of the energy ray-curable compound in the X-type adhesive composition is within the above range, the balance between the adhesive force before the irradiation with energy rays and the peelability after the irradiation with energy rays tends to be good.

The content of the energy ray-curable compound in the XY-type adhesive composition is not particularly limited, but is preferably 1 to 30 parts by mass, more preferably 2 to 20 parts by mass, and further preferably 3 to 15 parts by mass, relative to 100 parts by mass of the adhesive resin.

When the content of the energy ray-curable compound in the XY-type adhesive composition is within the above range, the balance between the adhesive force before the irradiation with energy rays and the peelability after the irradiation with energy rays tends to be good. Since the adhesive resin is energy ray-curable in the XY-type adhesive composition, the peeling force tends to be sufficiently reduced after irradiation with energy rays even if the content of the energy ray-curable compound is small.

(Crosslinking agent)

The adhesive composition preferably further contains a crosslinking agent.

The crosslinking agent is, for example, a component that crosslinks the adhesive resins by reacting with functional groups derived from the functional group-containing monomer that the adhesive resins have.

The crosslinking agent may be used alone or in combination of two or more.

Examples of the crosslinking agent include isocyanate crosslinking agents such as toluene diisocyanate, hexamethylene diisocyanate and adducts thereof, epoxy crosslinking agents such as ethylene glycol glycidyl ether, aziridine crosslinking agents such as hexa [1- (2-methyl) -aziridinyl ] triphosphoric acid triazine, chelate crosslinking agents such as aluminum chelate compounds, and the like. Among them, the isocyanate-based crosslinking agent is preferable from the viewpoint of further improving the cohesive force and the adhesive force, and from the viewpoint of easy acquisition.

When the pressure-sensitive adhesive composition contains a crosslinking agent, the content thereof is not particularly limited, but from the viewpoint of properly conducting the crosslinking reaction, the content is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 4 parts by mass, relative to 100 parts by mass of the pressure-sensitive adhesive resin.

(Photopolymerization initiator)

In the case where the adhesive is an energy ray curable adhesive, the adhesive composition preferably further contains a photopolymerization initiator. By incorporating the photopolymerization initiator in the energy ray-curable adhesive, the curing reaction of the energy ray-curable adhesive tends to be sufficiently progressed even by using energy rays of relatively low energy such as ultraviolet rays.

The photopolymerization initiator may be used alone or in combination of two or more.

Examples of the photopolymerization initiator include benzoin compounds, acetophenone compounds, acylphosphine oxide compounds, titanocene compounds, thioxanthone compounds, peroxide compounds, and photosensitizers such as amines and quinones, and more specifically, examples thereof include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, butanedione, 8-chloroanthraquinone, phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide, and the like.

When the adhesive composition contains a photopolymerization initiator, the content thereof is not particularly limited, but is preferably 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, relative to 100 parts by mass of the adhesive resin, from the viewpoint of uniformly and sufficiently conducting the energy ray curing reaction.

(Other additives)

The adhesive composition may contain other additives within a range that does not impair the effects of the present invention. Examples of the other additives include antistatic agents, antioxidants, softeners, fillers, rust inhibitors, pigments, dyes, and the like.

(Organic solvent)

From the viewpoint of further improving the coatability to a substrate, a release sheet, or the like, the adhesive composition may be diluted with an organic solvent to be prepared in the form of a solution.

Examples of the organic solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran and di-methyl ethyl ketoneAn alkane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, etc.

The organic solvent may be used alone or in combination of two or more.

The organic solvent may be used as it is, or one or more organic solvents other than the organic solvent used in the synthesis may be added.

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

When the storage modulus G' of the adhesive layer at 23 ℃ is in the above range, even when the surface of the work has irregularities, an adhesive layer excellent in the following property to the irregularities can be obtained, and the surface of the work can be more favorably protected during processing.

In the case where the adhesive layer is formed of an energy ray-curable adhesive, the storage modulus G 'of the adhesive layer means the storage modulus G' before curing by irradiation of energy rays.

The storage modulus G' of the adhesive layer at 23℃can be measured by cutting an adhesive layer having a thickness of 3mm into a circular shape having a diameter of 8mm, and using the resultant as a test piece, measuring the resultant by a torsional shear method using a viscoelasticity measuring device at a frequency of 1Hz and a measuring temperature of 23 ℃.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but is preferably 5 to 100. Mu.m, more preferably 10 to 80. Mu.m, still more preferably 15 to 60. Mu.m.

When the thickness of the adhesive layer is equal to or greater than the lower limit, excellent adhesion can be obtained, and the surface of the workpiece can be more favorably protected during processing. When the thickness of the adhesive layer is equal to or less than the upper limit, generation of the chip at the time of cutting the adhesive sheet can be suppressed, and breakage of the work piece can be prevented more satisfactorily.

< Substrate >

Examples of the base material include various resin films. Examples of the resin constituting the resin film include polyethylene such as Low Density Polyethylene (LDPE), linear Low Density Polyethylene (LLDPE) and High Density Polyethylene (HDPE), polyolefin such as polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymer and norbornene resin, 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, polyester such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate and wholly aromatic polyester, polyurethane, polyimide, polyamide, polycarbonate, fluororesin, polyacetal, modified polyphenylene ether, polyphenylene sulfide, polysulfone, polyether ketone and acrylic polymer.

The base material may be a single-layer film of a resin film formed from one or more resins selected from these resins, or may be a laminated film obtained by laminating two or more of these resin films. Further, the resin may be a modified film such as a crosslinked film or an ionomer film.

Among these resin films, the base material is preferably at least one selected from the group consisting of a polyester film, a polyamide film, a polyimide film and a biaxially oriented polypropylene film, more preferably a polyester film, and still more preferably a polyethylene terephthalate film.

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

When the young's modulus of the base material is equal to or greater than the lower limit value, the vibration suppressing effect during work tends to be further improved. When the young's modulus of the base material is equal to or less than the upper limit, workability in adhering to a workpiece and workability in peeling from the workpiece tend to be good.

The Young's modulus of the substrate can be measured under the conditions of a test speed of 200 mm/min based on JIS K7127:1999.

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

When the thickness of the base material is equal to or greater than the lower limit, sufficient strength tends to be obtained for functioning as a support of the adhesive sheet. When the thickness of the base material is equal to or less than the upper limit, adequate flexibility and improved handleability tend to be obtained.

The "thickness of the substrate" refers to the thickness of the entire substrate, and when the substrate is a substrate composed of a plurality of layers, the "thickness of the substrate" refers to the total thickness of all the layers constituting the substrate.

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

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

In view of improving the adhesion to other layers, at least one surface of the substrate may be subjected to a surface treatment such as corona treatment, or a coating layer may be provided for the purpose of improving the adhesion.

< Release sheet >

The pressure-sensitive adhesive sheet of the present embodiment may be formed by attaching a release sheet to at least one of the surface of the pressure-sensitive adhesive layer and the surface of the surface coating layer. The release sheet protects the surface of the adhesive sheet before use by being attached thereto in a releasable manner, and is peeled off and removed when the adhesive sheet is used.

The release sheet may be a release sheet subjected to a single-sided release treatment or a release sheet subjected to a double-sided release treatment.

The release sheet is preferably a release sheet having a release agent coated on a release sheet substrate.

The base material for the release sheet is preferably a resin film, 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, and the like.

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

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

< Total thickness of adhesive sheet >

The total thickness of the pressure-sensitive adhesive sheet of the present embodiment is not particularly limited, but is preferably 30 to 300. Mu.m, more preferably 40 to 220. Mu.m, and still more preferably 45 to 160. Mu.m.

When the total thickness of the adhesive sheet is equal to or greater than the lower limit, the adhesive performance of the adhesive layer, the impact absorbing performance of the buffer layer, and the like can be appropriately maintained, and the function as the adhesive sheet for processing a workpiece tends to be sufficiently exhibited. When the total thickness of the adhesive sheet is equal to or less than the upper limit value, the peeling force when peeling the work from the adhesive sheet tends to be reduced.

In the present embodiment, the "total thickness of the adhesive sheet" refers to a thickness from the surface of the surface coating layer of the adhesive sheet to the surface of the adhesive layer, and when the release sheet is provided, the thickness of the release sheet is not included in the total thickness.

< Method for producing adhesive sheet >

The method for producing the pressure-sensitive adhesive sheet of the present embodiment is not particularly limited, and can be produced by a known method.

The pressure-sensitive adhesive sheet of the present embodiment can be produced, for example, by a method including a step of forming a pressure-sensitive adhesive layer on one surface side of a substrate (hereinafter, also referred to as "pressure-sensitive adhesive layer forming step"), a step of forming a buffer layer on the other surface side of the substrate (hereinafter, also referred to as "buffer layer forming step"), and a step of forming a surface coating layer on the surface of the buffer layer opposite to the substrate (hereinafter, also referred to as "surface coating layer forming step"). The order of these steps is not particularly limited, and may be performed simultaneously if they can be performed simultaneously.

Examples of the method for forming the pressure-sensitive adhesive layer, the buffer layer or the surface coating layer include a method in which a pressure-sensitive adhesive composition, a buffer layer-forming composition or a surface coating layer-forming composition is applied to a predetermined position by a known method, and then, if necessary, energy ray irradiation and heat drying are performed.

Examples of the method for applying the adhesive composition, the composition for forming a buffer layer, or the composition for forming a surface coating layer include spin coating, spray coating, bar coating, doctor blade coating, roll coating, blade coating, die coating, and gravure coating.

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

In the buffer layer forming step, the buffer layer forming composition may be coated on the release sheet or directly on the surface of the substrate. When the composition for forming a buffer layer is coated on the release sheet, a layer formed from the composition for forming a buffer layer (hereinafter, also referred to as "composition layer for forming a buffer layer") on the release sheet is then adhered to the surface of the substrate. The buffer layer-forming composition layer on the release sheet may be the buffer layer itself, or may be an uncured or semi-cured product of the buffer layer-forming composition having curability when the buffer layer-forming composition is a curable composition. When an uncured or semi-cured product of the composition for forming a buffer layer is formed on the substrate, a treatment for completely curing the composition for forming a buffer layer is then performed.

In the surface coating layer forming step, the composition for forming a surface coating layer may be applied to the release sheet or directly to the surface of the buffer layer.

The drying temperature after the application of the surface coating layer forming composition is preferably 105 to 150 ℃, more preferably 110 to 140 ℃, and even more preferably 115 to 130 ℃ from the viewpoint of productivity and quality stability of the adhesive sheet.

In addition, from the viewpoint of productivity and stability of quality of the adhesive sheet, the drying time after the application of the surface coating layer forming composition is preferably 0.1 to 60 minutes, more preferably 0.3 to 30 minutes, and still more preferably 0.5 to 5 minutes.

When the composition for forming a surface coating layer is coated on the release sheet, a layer formed from the composition for forming a surface coating layer (hereinafter, also referred to as "composition layer for forming a surface coating layer") on the release sheet is then adhered to the surface of the buffer layer. The surface coating layer-forming composition layer on the release sheet may be the surface coating layer itself, or may be an uncured or semi-cured product of the curable surface coating layer-forming composition in the case where the surface coating layer-forming composition is a curable composition. When an uncured or semi-cured product of the composition for forming a surface coating layer is formed on the buffer layer, a treatment for completely curing the composition for forming a surface coating layer is then performed.

The buffer layer forming step and the surface coating layer forming step may be a method of sequentially disposing a surface coating layer and a buffer layer 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 energy rays.

In the case where the composition for forming a buffer layer contains an energy ray polymerizable compound, the curing treatment by irradiation with energy rays may be performed once or in multiple times.

In the case where the curing treatment by the irradiation of energy rays is performed in one step, the composition for forming a buffer layer may be completely cured by the irradiation of energy rays after the coating film of the composition for forming a buffer layer is formed on the substrate, or may be bonded to the substrate after the composition for forming a buffer layer is completely cured on the release sheet.

When the composition for forming a surface coating layer is an organic layer containing a resin component and contains an energy ray-polymerizable polyfunctional compound, the step of forming a surface coating layer preferably includes a step of forming the surface coating layer by irradiating an energy ray to the composition for forming a surface coating layer containing the resin component, the energy ray-polymerizable polyfunctional compound and a photopolymerization initiator.

The irradiation time of the energy ray to the surface coating layer forming composition is not particularly limited, and may be any time before or after the composition for forming a surface coating layer is laminated on the buffer layer or the composition for forming a buffer layer.

In the case of the curing treatment of the buffer layer forming composition in multiple steps, after the coating film of the buffer layer forming composition is formed on the release sheet, the buffer layer forming composition may be completely cured on the release sheet by bonding the layer of the surface coating layer forming composition provided on the release sheet after curing the buffer layer forming composition to a semi-cured state, and then radiating energy rays again. When the composition for forming a surface coating layer contains an energy ray polymerizable polyfunctional compound, the composition for forming a surface coating layer can be simultaneously cured by radiating energy rays to completely cure the composition for forming a buffer layer.

The energy rays irradiated during the curing treatment of the composition for forming a buffer layer and the composition for forming a surface coating layer are preferably ultraviolet rays.

When the composition for forming a buffer layer and the composition for forming a surface coating layer are cured by irradiation with energy rays, the composition for forming a buffer layer and the composition for forming a surface coating layer may be exposed to the outside, but it is preferable to irradiate energy rays in a state where both surfaces are covered with a member such as a release sheet or a base material and are not exposed to the outside.

< Use of adhesive sheet >

Examples of the processing of the work in a state where the adhesive sheet of the present embodiment is attached include back grinding processing for grinding the other surface of the work in a state where the adhesive sheet is attached to one surface of the work, cutting processing for singulating the work in a state where the adhesive sheet is attached to one surface of the work, conveying the work, and picking up individual pieces of the work.

The adhesive sheet of the present embodiment is suitable for grinding a workpiece, is more suitable for back grinding of a workpiece, and is further suitable for back grinding of a back surface of a workpiece in a state where the adhesive sheet of the present embodiment is attached to a circuit forming surface of the workpiece. In particular, the pressure-sensitive adhesive sheet of the present embodiment has an effect of suppressing occurrence of cracks when the workpiece is thinned, and is therefore suitable for processes such as a pre-dicing method and a stealth pre-dicing method.

[ Method for manufacturing electronic device apparatus ]

The method for manufacturing an electronic device according to the present embodiment includes:

A step of adhering the adhesive sheet for processing a workpiece of the present embodiment to the surface of the workpiece with the adhesive layer as an adhering surface, and

And grinding the back surface of the workpiece in a state where the surface coating layer side of the adhesive sheet for workpiece processing attached to the workpiece is fixed by a supporting means.

In addition, the method for manufacturing the electronic device according to the present embodiment preferably includes:

a dividing scheduled line forming step of forming a groove on the surface of a workpiece or a step of forming a modified region in the workpiece from the surface or the back of the workpiece;

a sheet adhering step of adhering the adhesive sheet for processing a workpiece of the present embodiment to the surface of the workpiece with the adhesive layer as an adhering surface after the step a or before or after the step b, and

And grinding and singulating the back surface of the workpiece by grinding the back surface of the workpiece in a state in which the surface coating layer side of the adhesive sheet for workpiece processing attached to the workpiece is fixed by a supporting means, and singulating the workpiece into a plurality of workpiece singulated products using the grooves or the modified regions as starting points.

Further, the method for manufacturing an electronic device according to the present embodiment may include a peeling step of peeling the adhesive sheet for processing a workpiece according to the present embodiment from a plurality of workpieces after the grinding and singulation steps.

The method of manufacturing the electronic device having the step a is a process corresponding to a dicing method, and the method of manufacturing the electronic device having the step b is a process corresponding to a stealth dicing method.

Hereinafter, each step of the method for manufacturing an electronic device according to the present embodiment will be described in detail.

< Procedure for Forming lines to divide >

The planned dividing line forming step is a step a of forming a groove in the surface of the workpiece, or a step b of forming a modified region in the workpiece from the surface or the back surface of the workpiece.

The step a is a step of forming a groove in the surface of the work, and is performed before the adhesive sheet is adhered to the surface of the work.

The groove formed in the surface of the workpiece in step a is a groove having a depth shallower than the thickness of the workpiece. After the step a, the workpiece is back-ground to the groove position formed in the step a, and is divided into a plurality of workpiece singulated products. Therefore, in the step a, grooves are formed along the dividing line when dividing and singulating the work piece.

The grooves may be formed by dicing using a conventionally known wafer dicing apparatus or the like.

The step b is a step of forming a modified region in the workpiece from the front or back surface of the workpiece, and may be performed before or after the adhesive sheet is attached to the front surface of the workpiece.

In step b, a laser beam is irradiated to focus the focal point on the inside of the workpiece, thereby forming a modified region in the inside of the workpiece. The modified region is a portion of the workpiece where embrittlement occurs, and is a region where the workpiece becomes thinner by back grinding or is broken by application of a grinding force, and thus becomes a starting point for singulation of the workpiece. Therefore, the modified region is formed along the dividing line when the workpiece is divided and singulated.

The irradiation of the laser light may be performed from the front surface side or the back surface side of the workpiece. In the case of performing the step b after the sheet bonding step, the work may be irradiated with laser light through the adhesive sheet.

< Sheet adhesion Process >

The sheet adhering step is a step of adhering the adhesive sheet to the surface of the work with the adhesive layer as an adhering surface after the step a or before or after the step b.

The method of adhering the pressure-sensitive adhesive sheet is not particularly limited, and a conventionally known method using a laminator or the like can be used, for example.

< Grinding and singulation Process >

The grinding and singulation step is a step of grinding the back surface of the workpiece in a state where the front surface coating side of the adhesive sheet attached to the workpiece is fixed by the supporting means, and singulating the workpiece into a plurality of workpiece singulated products with the groove or the modified region as a starting point.

The surface coating side of the adhesive sheet is fixed by a supporting device to a work on which the adhesive sheet is adhered and grooves or modified regions are formed. The support device is not particularly limited, and is preferably a device for holding the object to be fixed by suction, such as a chuck table.

Then, the back surface of the fixed workpiece is ground, and the workpiece is singulated into a plurality of workpiece singulated products.

In the back grinding, when a groove is formed in the workpiece in the step a, the workpiece is ground at least to a position where the grinding surface reaches the bottom of the groove. By this back grinding, the groove becomes a notch penetrating the workpiece, and the workpiece is divided by the notch and singulated into individual workpiece singulated products.

On the other hand, when the workpiece is formed with the modified region in the step b, the ground surface may reach the modified region, but may not strictly reach the modified region. That is, the workpiece may be ground to a position close to the modified region, and the workpiece may be broken and singulated from the modified region. For example, after grinding to a position close to the modified region without singulating the workpiece, a pick-up tape may be attached to the workpiece, and the pick-up tape may be stretched to singulate the semiconductor chips.

The workpiece monolithic product after being singulated may have a square shape or an elongated shape such as a rectangle.

The thickness of the singulated workpiece 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 size of the singulated workpiece after singulation is not particularly limited, but is preferably less than 50mm ², more preferably less than 30mm ², and even more preferably less than 10mm ².

< Stripping Process >

The peeling step is a step of peeling the adhesive sheet from the plurality of workpiece singulated products after the grinding and singulation step.

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

In the case of peeling the adhesive sheet, a pickup tape may be used. The pickup tape may be constituted by an adhesive sheet including a base material and an adhesive layer provided on one surface of the base material, for example.

In the case of using the pickup tape, first, the pickup tape is stuck to the back surface side of the singulated workpiece, and alignment is performed so that the pickup can be performed. In this case, it is preferable that the annular frame disposed on the outer peripheral side of the workpiece singulated product is also bonded to the pickup belt, and the outer peripheral edge portion of the pickup belt is fixed to the annular frame. Next, the adhesive sheet is peeled from the plurality of work individual pieces fixed to the pick-up belt.

Then, the plurality of workpiece singulated products located on the pickup tape may be picked up and then fixed on a substrate or the like, thereby manufacturing an electronic device apparatus.

Examples

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The measurement and evaluation methods of the various physical properties are as follows.

[ Weight average molecular weight (Mw) ]

The weight average molecular weight (Mw) was measured using a gel permeation chromatography apparatus (product name "HLC-8220" manufactured by Tosoh Co., ltd.) under the following conditions, and was obtained by conversion from standard polystyrene.

(Measurement conditions)

The column was: "TSK guard column HXL-H" "" TSK gel GMHXL (. Times.2) "," TSK gel G2000HXL "(manufactured by Tosoh Co., ltd.)

Column temperature of 40 DEG C

Eluting solvent tetrahydrofuran

Flow Rate 1.0mL/min

[ Measurement of thickness of pressure-sensitive adhesive sheet etc. ]

The total thickness of the adhesive sheet, the thickness of each layer, and the thickness of a test piece produced from the layers were measured by a constant pressure thickness gauge (trade name "PG-02", manufactured by Kyowa Co., ltd.). At this time, 10 arbitrary points were measured, and an average value was calculated.

The total thickness of the adhesive sheet is a value obtained by measuring the thickness of the adhesive sheet with the release sheet and subtracting the thickness of the release sheet from the thickness.

The thickness of the buffer layer is a value obtained by subtracting the thickness of the base material from the thickness of the base material with the buffer layer.

The thickness of the surface coating layer is a value obtained by subtracting the thickness of the release sheet from the thickness of the surface coating layer with the release sheet.

The thickness of the adhesive layer is obtained by subtracting the thicknesses of the surface coating layer, the buffer layer, and the base material from the total thickness of the adhesive sheet.

[ Measurement of diiodomethane contact Angle of surface coating layer ]

The diiodomethane contact angle of the surface coating layer was measured based on JIS R3257:1999. Specifically, the release sheets on the surface coating layer side of the pressure-sensitive adhesive sheets produced in examples and comparative examples were peeled off, and the static contact angle at the time of dropping diiodomethane onto the surface of the exposed surface coating layer was measured using a fully automatic contact angle measuring instrument (product name "DM-701" manufactured by synergistic interface science co., ltd.) under the following conditions.

Measurement temperature of 23 DEG C

Drop volume 2. Mu.l

Measurement time after 1 second of dropwise addition

Image analysis method [ theta ]/2 method

[ Evaluation of the surface coating layer adhesion amount of grinding chip ]

The pressure-sensitive adhesive sheets produced in examples and comparative examples and having release sheets on both sides were cut into a size of 5cm square in plan view, and the release sheets on the surface coating layer side were peeled off to prepare test pieces with the surface coating layer exposed. Any 1 of the 4 corners of the test piece was fixed and hung, and immersed in grinding water containing 5 mass% of the grinding dust of the silicon wafer for 10 minutes. The test piece was taken out of the grinding water, left in a suspended state, left to stand at 23 ℃ for 24 hours, dried, and then visually observed for the surface coating layer of the test piece, and the adhesion amount of the grinding dust was evaluated according to the following criteria. In the following evaluation criteria, "chip-adhering portion" refers to an island-shaped chip-adhering portion formed by drying droplets of grinding water adhering to the surface coating layer.

And (A) 1 part of the surface coating layer is provided with a grinding chip attaching part or the grinding chip is not attached to the surface coating layer to the extent that the grinding chip attaching part can be identified.

And B, 2-5 grinding chip adhesion parts are arranged on the surface coating layer.

And C, more than 6 grinding chip attaching parts are arranged on the surface coating layer, but the grinding chips are not attached to the whole surface of the surface coating layer.

And D, adhering grinding scraps on the whole surface of the surface coating layer.

[ Preparation of urethane acrylate oligomer for buffer layer ]

Production example 1

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

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

Production example 2

An acrylic polymer was obtained by copolymerizing 52 parts by mass of n-butyl acrylate, 20 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate. Then, 2-methacryloyloxyethyl isocyanate was reacted so as to be added to 90 mol% of all hydroxyl groups of the acrylic polymer, thereby obtaining an energy ray-curable acrylic resin having a weight average molecular weight (Mw) of 50 ten thousand.

[ Production of adhesive sheet ]

Examples 1 to 4 and comparative examples 1 to 2

Next, an adhesive sheet was produced by the following method. The amounts of the components blended in the following description all represent the amounts of the active ingredients blended.

(1) Preparation of a substrate

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

(2) Preparation of composition for Forming surface coating layer

Each component shown in table 1 was dissolved in toluene so that the effective component concentration became 10 mass%, and a composition for forming a surface coating layer was obtained.

(3) Preparation of composition for Forming buffer layer

A buffer layer-forming composition was prepared by blending 40 parts by mass of the urethane acrylate oligomer obtained in production example 1, 40 parts by mass of isobornyl acrylate, 20 parts by mass of 2-hydroxy-3-phenoxypropyl acrylate, 2.0 parts by mass of 1-hydroxycyclohexyl phenyl ketone as a photopolymerization initiator, and 0.2 parts by mass of a phthalocyanine pigment.

(4) Preparation of adhesive composition

An adhesive composition was prepared by mixing 100 parts by mass of the energy ray-curable acrylic resin obtained in production example 2, 6 parts by mass of a polyfunctional urethane acrylate (trade name "Shikou UT-4332", weight average molecular weight (Mw) 4,700) as an energy ray-curable compound, 0.375 part by mass of an isocyanate-based crosslinking agent (trade name "cornonate L", manufactured by eastern co.) and 1 part by mass of phenylbis (2, 4, 6-trimethylbenzoyl) phosphine oxide as a photopolymerization initiator, and diluting with an organic solvent.

(5) Production of adhesive sheet

After the buffer layer forming composition obtained above was applied to one surface of the substrate as described above so that the thickness of the formed buffer layer became 20 μm, the buffer layer forming composition was semi-cured by irradiation with ultraviolet light under the conditions of illuminance of 30mW/cm ² and irradiation dose of 60mJ/cm ², and a layer obtained by semi-curing the buffer layer forming composition was formed on one surface of the substrate.

The composition for forming a surface coating layer obtained as described above was applied to the release treated surface of a release sheet (trade name "SP-PET381031" manufactured by linde corporation) using a meyer rod so that the thickness of the formed surface coating layer became 2 μm, and then heated and dried at 120 ℃ for 1 minute, whereby a composition layer for forming a surface coating layer was formed on the release sheet.

After bonding the composition layer for forming a surface coating layer on the release sheet to the layer formed by semi-curing the composition for forming a buffer layer formed on one side of the substrate, the composition for forming a buffer layer and the composition for forming a surface coating layer were cured by irradiation with ultraviolet rays under conditions of an illuminance of 160mW/cm ² and an irradiation amount of 500mJ/cm ², thereby obtaining a laminate having a buffer layer and a surface coating layer in this order on one side of the substrate.

The pressure-sensitive adhesive composition obtained above was applied to a release treated surface of a release sheet (trade name "SP-PET381031" manufactured by lindeke corporation) so that the thickness after drying became 20 μm, and then dried by heating, to prepare a release sheet with a pressure-sensitive adhesive layer.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-attached release sheet was adhered to the surface of the base material provided in the laminate, on which no buffer layer was provided, to thereby obtain a pressure-sensitive adhesive sheet having a release sheet on both surfaces and a surface coating layer, a buffer layer, a base material, and a pressure-sensitive adhesive layer in that order.

The evaluation results of the adhesive sheets obtained in each example and comparative example are shown in table 1.

TABLE 1

(Resin component)

S2104 hydrogenated styrene thermoplastic elastomer (SEPS), styrene content: 65% by mass, manufactured by Kuraray, inc., trade name "SEPTON (registered trademark) 2104"

Energy ray polymerizable polyfunctional Compound, which is a mixture of dipentaerythritol hexaacrylate and dipentaerythritol pentaacrylate, and which is available under the trade name "KAYARAD DPHA" from Japanese chemical Co., ltd "

Subjected to hydrophobization treated silica: amorphous precipitated silica having been hydrophobicized

(Photopolymerization initiator)

Omnirad 651:2, 2-dimethoxy-2-phenylacetophenone, molecular weight 256.3, manufactured by IGM resins B.V

Omnirad 907:2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one, molecular weight 279.4, IGM RESINS B.V.)

Omnirad 127:2-hydroxy-1- {4- [4- (2-hydroxy-2-methylpropanoyl) benzyl ] phenyl } -2-methylpropan-1-one, molecular weight 340.4, IGM RESINS B.V.)

Omnirad 1173:2-hydroxy-2-methyl-1-phenylpropion, molecular weight 164.2, manufactured by IGM resins B.V

OmnirAD 184:1-hydroxycyclohexyl phenyl ketone, molecular weight 204.3, IGM RESINS B.V.)

According to table 1, in the adhesive sheets of examples 1 to 4 in which the diiodomethane contact angle of the surface coating layer was 43 ° or more, the adhesion amount of the grinding dust was sufficiently reduced although the composition for forming the surface coating layer was dried at a high temperature in a short time when the surface coating layer was formed. From the results, it can be seen that this practice

The adhesive sheet for workpiece processing according to the embodiment is excellent in productivity, and the amount of adhesion of the grinding dust is suppressed. On the other hand, the adhesive sheets of comparative examples 1 and 2 having the diiodomethane contact angle of the surface coating layer of less than 43 ° were insufficient in reduction of the adhesion amount of the chips.

Claims (10)

1. An adhesive sheet for workpiece processing, which comprises a surface coating layer, a buffer layer, a substrate and an adhesive layer in sequence, The static contact angle of diiodomethane with respect to the surface coating layer at 23° C. is 43° or more. 2. The adhesive sheet for workpiece processing according to claim 1, wherein: The surface coating layer is an organic layer containing a resin component. 3. The adhesive sheet for workpiece processing according to claim 2, wherein: The resin component is a polymer of a compound having one or more ethylenically unsaturated bonds. 4. The adhesive sheet for workpiece processing according to claim 3, wherein: The compound having one or more ethylenically unsaturated bonds is a styrene compound. 5. The adhesive sheet for workpiece processing according to any one of claims 1 to 4, wherein The thickness of the surface coating layer is 0.05-10 μm. 6. The adhesive sheet for workpiece processing according to any one of claims 1 to 4, wherein The buffer layer is a layer formed from a buffer layer-forming composition containing urethane (meth)acrylate. 7 . The adhesive sheet for workpiece processing according to claim 1 , which is used for grinding a workpiece. 8. A method for producing an adhesive sheet for workpiece processing, which is a method for producing the adhesive sheet for workpiece processing according to any one of claims 2 to 4, the method comprising: A step of forming the surface coating layer by irradiating a composition for forming a surface coating layer containing the resin component, an energy-ray-polymerizable polyfunctional compound, and a photopolymerization initiator with energy rays. 9. A method for manufacturing an electronic device, the method comprising: A step of attaching the workpiece processing adhesive sheet according to any one of claims 1 to 4 to a surface of a workpiece with the adhesive layer as an attachment surface; and A step of grinding the back surface of the workpiece in a state where the surface coating layer side of the workpiece processing pressure-sensitive adhesive sheet adhered to the workpiece is fixed by a supporting device. 10. A method for manufacturing an electronic device, the method comprising: a planned dividing line forming step, which is step a of forming a groove on the surface of the workpiece, or step b of forming a modified region inside the workpiece from the surface or back surface of the workpiece; a sheet sticking step of sticking the workpiece processing adhesive sheet according to any one of claims 1 to 4 to the surface of the workpiece with the adhesive layer as a sticking surface after the step a or before or after the step b; and The grinding and singulation step grinds the back side of the workpiece while the surface coating layer side of the workpiece processing adhesive sheet adhered to the workpiece is fixed by a supporting device, and singulates the workpiece into a plurality of workpiece singulation products starting from the groove or the modified region.