Adhesive sheets for workpiece processing, and semiconductor devices.

Abstract

To provide an adhesive sheet for workpiece processing that suppresses the occurrence of Yuzu / orange skin.SOLUTION: Provided is an adhesive sheet for workpiece processing (100), which is an adhesive sheet for workpiece processing (100) comprising a substrate (10), an adhesive layer (20) provided on one side of the substrate (10), and a release film (30) provided on the surface (20A) of the adhesive layer (20) opposite to the substrate (10), and in which the maximum cross-sectional height St of the surface (30B) on the adhesive layer (20) side of the release film (30) is 0.45 μm or more, and the root-mean-square height Sq is 17.5 nm or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an adhesive sheet for workpiece processing and a semiconductor device.

Background Art

[0002] For example, a semiconductor device is manufactured through various processes such as a back grinding process, a dicing process, an expand process, a transfer process, and a pickup process. Specifically, for example, a semiconductor wafer is cut into a predetermined shape and dimensions and separated into a plurality of semiconductor chips. After expanding the mutual interval of each of the separated chips, they are mounted on a mounting object such as a lead frame and a substrate. In the manufacturing process of a semiconductor device, workpieces such as a semiconductor wafer and a semiconductor package are in a state of being attached to the adhesive layer of an adhesive sheet for workpiece processing having a base material and an adhesive layer provided on the base material, and various processes are performed in each of the above processes.

[0003] Also, for example, a transparent member such as a glass substrate and a glass plate is processed using an adhesive sheet for workpiece processing having a base material and an adhesive layer. For example, the transparent member is attached to the adhesive layer of the adhesive sheet for workpiece processing and then cut into a predetermined shape and dimensions to be separated into a plurality of chip-shaped transparent members (for example, glass chips).

[0004] Patent Document 1 describes an adhesive sheet including at least a release film having a release-treated surface after release treatment and an adhesive layer formed on the release-treated surface. The adhesive sheet has physical properties that (1) the surface roughness (Ra) of the release-treated surface of the release film is 100 nm or less, and (2) the 180° peel strength of the release-treated surface of the release film from the adhesive layer is 10.0 gf / 25 mm width or more and 50.0 gf / 25 mm width or less at a peel rate of 5 mm / min and 500 mm / min.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2010-185038 [Overview of the project] [Problems that the invention aims to solve]

[0006] In adhesive sheets for workpiece processing, a release film may be provided on the side opposite to the side where the substrate of the adhesive layer is located (hereinafter sometimes referred to as the adhesive surface of the adhesive layer). For example, in adhesive sheets for workpiece processing, a release film is laminated in contact with the adhesive surface of the adhesive layer for the purpose of protecting the adhesive surface of the adhesive layer until the workpiece processing sheet is used.

[0007] When a release film is laminated in contact with the adhesive surface of an adhesive layer, fine irregularities can form on the adhesive surface of the adhesive layer, resulting in a defect in the appearance of the adhesive sheet used for workpiece processing. This phenomenon is known as "orange peel." Although the reason is unknown, it has been found that when a release film with a highly smooth surface on the side in contact with the adhesive layer (i.e., the release treatment surface of the release film) is laminated onto the adhesive layer, there is a tendency for defects in appearance to occur.

[0008] The object of the present invention is to provide an adhesive sheet for workpiece processing that suppresses the occurrence of orange peel texture, and a semiconductor device using the adhesive sheet for workpiece processing. [Means for solving the problem]

[0009] According to one embodiment of this invention, there is an adhesive sheet for workpiece processing comprising a base material, an adhesive layer provided on one side of the base material, and a release film provided on the side of the adhesive layer opposite to the base material, wherein the maximum cross-sectional height St of the side of the release film facing the adhesive layer is 0.45 μm or more, and the root mean square height Sq is 17.5 nm or more.

[0010] In an adhesive sheet for workpiece processing according to one aspect of this embodiment, It is preferable that the surface of the workpiece having an arithmetic mean roughness Ra of 0.005 μm or less is attached to the adhesive layer.

[0011] In one aspect of this embodiment, the adhesive sheet for workpiece processing preferably contains a filler.

[0012] In an adhesive sheet for workpiece processing according to one aspect of this embodiment, it is preferable that the adhesive layer is an adhesive layer that is curable by energy rays.

[0013] In one aspect of this embodiment, the workpiece to be attached to the adhesive layer is preferably a transparent material.

[0014] In one aspect of this embodiment, the adhesive sheet for workpiece processing is preferably made of glass.

[0015] In one aspect of this embodiment, the adhesive sheet for workpiece processing is preferably a dicing sheet.

[0016] According to one aspect of this embodiment, a semiconductor device manufactured using an adhesive sheet for workpiece processing according to one aspect of this embodiment is provided. [Effects of the Invention]

[0017] According to the present invention, an adhesive sheet for workpiece processing that suppresses the occurrence of orange peel texture, and a semiconductor device using the adhesive sheet for workpiece processing can be provided. [Brief explanation of the drawing]

[0018] [Figure 1] This is a schematic diagram showing an example of an adhesive sheet for workpiece processing according to this embodiment. [Figure 2] This is a schematic diagram showing the state of the adhesive sheet for workpiece processing according to this embodiment after the release film has been peeled off.

Best Mode for Carrying Out the Invention

[0019] Hereinafter, a preferred embodiment of the adhesive sheet for work processing according to the present invention will be described.

[0020] [Adhesive Sheet for Work Processing] The adhesive sheet for work processing according to the present embodiment includes a base material, an adhesive layer provided on one surface of the base material, and a release film provided on the surface of the adhesive layer opposite to the base material, and is an adhesive sheet for work processing. The maximum cross-sectional height St of the surface of the release film on the adhesive layer side is 0.45 μm or more, and the root mean square height Sq is 17.5 nm or more.

[0021] The adhesive sheet for work processing according to the present embodiment has the above configuration, so that the generation of orange peel on the adhesive surface of the adhesive layer is suppressed. The surface of the release film on the side in contact with the adhesive layer (that is, the release treatment surface of the release film) is a surface having irregularities, and by laminating the adhesive layer on this surface having irregularities, the surface of the adhesive sheet for work processing to be attached to the work (that is, the adhesive surface of the adhesive layer) becomes a smooth surface without orange peel. By suppressing the generation of orange peel, the product yield is improved. The release film is laminated on the adhesive surface of the adhesive layer, for example, until the adhesive sheet for work processing is used.

[0022] Here, "orange peel" means irregularities such as the surface of the skin of "yuzu", which is a kind of citrus fruit. Orange peel can be observed in a state where the release film is peeled off from the adhesive surface of the adhesive layer, and when the release film is transparent, it can also be observed in a state where the release film is in contact with and laminated on the adhesive surface of the adhesive layer.

[0023] The adhesive sheet for workpiece processing according to this embodiment will be described with reference to the drawings. Figure 1 schematically shows a cross-section of the adhesive sheet for workpiece processing according to one embodiment, and Figure 2 schematically shows a cross-section of the adhesive sheet for workpiece processing according to one embodiment with the release film removed. Note that in the drawings, some parts have been enlarged or reduced in size for the sake of clarity.

[0024] As shown in Figure 1, the adhesive sheet 100 for workpiece processing comprises a base material 10 having a base material first surface 10A and a base material second surface 10B opposite to the base material first surface 10A; an adhesive layer 20 having an adhesive layer first surface 20A and an adhesive layer second surface 20B opposite to the adhesive layer first surface 20A; and a release film 30 having a release film first surface 30A and a release film second surface 30B opposite to the release film first surface 30A. The base material first surface 10A is the surface facing the adhesive layer 20, and the base material second surface 10B is the outer surface of the base material 10. The adhesive layer first surface 20A is the surface facing the release film 30, and the adhesive layer second surface 20B is the surface facing the base material 10. The release film first surface 30A is the outer surface of the release film 30, and the release film second surface 30B is the surface facing the adhesive layer 20. In the adhesive sheet 100 for workpiece processing, the adhesive layer 20 is laminated in direct contact with the first surface 10A of the base material, and the second surface 20B of the adhesive layer faces the first surface 10A of the base material. The release film 30 is laminated in direct contact with the first surface 20A of the adhesive layer (i.e., the surface of the adhesive layer 20 opposite to the base material 10), and the second surface 30B of the release film faces the first surface 20A of the adhesive layer. In other words, the adhesive sheet 100 for workpiece processing has the adhesive layer 20 and the release film 30 provided on one side of the base material 10 (the first surface 10A of the base material). The release film 30 is laminated on the first surface 20A of the adhesive layer 20, which is the adhesive surface of the adhesive layer 20, until the adhesive sheet 100 for workpiece processing is used.

[0025] As shown in Figure 2, when the adhesive sheet 100 for workpiece processing is used, the release film 30 of the adhesive sheet 100 for workpiece processing is peeled off. In the adhesive sheet 100 for workpiece processing, the second surface 30B of the release film (i.e., the surface on the adhesive layer 20 side) has a maximum cross-sectional height St of 0.45 μm or more and a root mean square height Sq of 17.5 nm or more.

[0026] Although the present invention has been described above with reference to the drawings, it is not limited to the embodiments shown in Figures 1 and 2. In this embodiment, the adhesive sheet 100 for workpiece processing has a release film 30 in contact with the adhesive surface (first surface 20A) of the adhesive layer 20, and the maximum cross-sectional height St of the surface of the release film 30 facing the adhesive layer 20 (second surface 30B of the release film) is 0.45 μm or more, and the root mean square height Sq is 17.5 nm or more. However, it is not particularly limited, and a layer other than the adhesive layer 20 may be provided between the substrate 10 and the adhesive layer 20.

[0027] The following describes specific examples of each layer constituting the adhesive sheet for workpiece processing according to this embodiment. In the following description, reference numerals are omitted.

[0028] <Base material> The base material is not particularly limited and should have performance suitable for processes in which the adhesive sheet for workpiece processing is used. The base material is preferably made of resin, and more preferably a resin film.

[0029] Examples of resins constituting the base material include polyester resins (polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, etc.), polyolefin resins (polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymer, norbornene resin, and ethylene copolymers (ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, and ethylene-(meth)acrylic acid ester copolymer, etc.)), polyvinyl chloride resins (polyvinyl chloride and vinyl chloride copolymer, etc.), (meth)acrylic acid ester copolymers, polyurethane, polyamide, polyimide, polystyrene, polycarbonate, fluororesin, and ionomer. The base material may be a single-layer film of the above resins, or a laminated film with two or more layers. If the base material is a laminated film, the resins in each layer may be the same type of resin or different types of resins.

[0030] In this specification, "(meth)acrylic" means both acrylic and methacrylic. The same applies to other similar terms.

[0031] At least one surface of the substrate may be treated with an easy-adhesion treatment, such as corona treatment, plasma treatment, flame treatment, primer treatment, and anchor coating treatment. If the surface of the substrate that is in contact with other layers (for example, the surface in contact with the adhesive layer) is treated with an easy-adhesion treatment, the adhesion with the other layer (for example, the adhesive layer) is improved.

[0032] The substrate may contain various additives as needed, such as colorants, flame retardants, plasticizers, antistatic agents, lubricants, and fillers. Furthermore, if the adhesive layer contains an energy ray curable compound as described later, it is preferable that the substrate be permeable to energy rays.

[0033] The thickness of the substrate is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 30 μm or more, and even more preferably 50 μm or more. The thickness of the substrate is preferably 500 μm or less, more preferably 300 μm or less, even more preferably 100 μm or less, and even more preferably 90 μm or less. If the substrate thickness is 5 μm or more, the adhesive sheet for workpiece processing tends to have sufficient strength to be suitable for processing workpieces, making it easier to support the workpiece. If the substrate thickness is 500 μm or less, the adhesive sheet for workpiece processing tends to have flexibility. Furthermore, if the substrate thickness is 5 μm or more, it becomes easier to perform tasks such as dicing the workpiece. If the substrate thickness is 500 μm or less, it becomes easier to perform tasks such as expanding the substrate.

[0034] The substrate can be obtained by known methods. For example, the substrate can be produced by molding a resin composition containing a resin and additives as needed, using methods such as casting, calendering, T-die extrusion, and inflation.

[0035] <Adhesive layer> The adhesive layer is not particularly limited and is formed from an adhesive composition containing various types of adhesives. Examples of adhesives include acrylic, rubber, silicone, urethane, polyester, and polyvinyl ether adhesives. The adhesive is selected considering the application and the type of workpiece to be attached. Among these, an acrylic adhesive is preferred from the viewpoint of easily exhibiting adhesive strength to the workpiece.

[0036] The adhesive may be a non-energy-ray curable adhesive that does not possess energy-ray curability, or it may be an energy-ray curable adhesive. Examples of energy rays include ultraviolet rays and electron beams.

[0037] If the adhesive is energy-ray curable, an adhesive layer is formed when the adhesive is irradiated with energy rays. As a result, the tackiness of the adhesive layer decreases, and the adhesive strength of the adhesive sheet for workpiece processing to the workpiece can be reduced. From this viewpoint, the adhesive is preferably an energy-ray curable adhesive, and more preferably an ultraviolet-curable adhesive.

[0038] (Energy ray curing adhesive) When an adhesive composition is energy-ray curable, the adhesive composition may contain the components exemplified in (I) to (III) below, and is preferably any one of (I), (II), or (III). Hereinafter, the components exemplified in (I) to (III) above that are included in an energy-ray curable adhesive composition may be collectively referred to as an adhesive resin.

[0039] (I): A component containing a non-energy ray curable polymer and an energy ray curable compound. (II): A component that does not contain an energy ray curable compound, but contains an energy ray curable polymer in which an unsaturated group is introduced into the side chain of a non-energy ray curable polymer. (III): A component containing an energy ray-curable polymer and an energy ray-curable polymer in which an unsaturated group is introduced into the side chain of a non-energy ray-curable polymer.

[0040] In adhesive resins, the non-energy ray curable polymer is preferably a (meth)acrylic copolymer. The adhesive composition preferably contains an energy ray curable compound.

[0041] [Energy ray curable compounds] Energy-ray curable compounds have energy-ray curable double bonds within their molecules. Energy-ray curable compounds are compounds that polymerize and harden when irradiated with energy rays (e.g., ultraviolet light).

[0042] The energy-ray curable compound is preferably a (meth)acrylic compound. The energy-ray curable compound is preferably an ultraviolet-curable compound. The energy-ray curable compound is more preferably an ultraviolet-curable (meth)acrylic compound.

[0043] Examples of energy-ray curable compounds include low molecular weight compounds having energy-ray polymerizable groups (monofunctional monomers, polyfunctional monomers, monofunctional oligomers, and polyfunctional oligomers). Specifically, energy-ray curable compounds include acrylates such as trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, pentaerythritol triacrylate, dipentaerythritol monohydroxypentaacrylate, dipentaerythritol hexaacrylate, 1,4-butylene glycol diacrylate, and 1,6-hexanediol diacrylate; cyclic aliphatic skeleton-containing acrylates such as dicyclopentadiene dimethoxydiacrylate and isobornyl acrylate; and acrylate compounds such as polyethylene glycol diacrylate, oligoester acrylate, urethane acrylate oligomer, epoxy-modified acrylate, polyether acrylate, and itaconic acid oligomer. Energy-ray curable compounds may be used individually or in combination of two or more.

[0044] The molecular weight of the energy ray-curable compound is usually between 100 and 30,000, and preferably between 300 and 10,000.

[0045] [(meth)acrylic copolymer] The adhesive may also preferably further contain a (meth)acrylic copolymer. The (meth)acrylic copolymer is different from the energy ray curable compound described above.

[0046] The (meth)acrylic copolymer preferably has an energy-curable carbon-carbon double bond. That is, the adhesive preferably contains an energy-curable compound and an energy-curable (meth)acrylic copolymer.

[0047] The adhesive preferably contains an energy-ray curable compound in an amount of 10 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, per 100 parts by mass of (meth)acrylic copolymer. The adhesive preferably contains an energy-ray curable compound in an amount of 200 parts by mass or less, more preferably 160 parts by mass or less, and even more preferably 120 parts by mass or less, per 100 parts by mass of (meth)acrylic copolymer.

[0048] The weight-average molecular weight (Mw) of the (meth)acrylic copolymer is preferably 50,000 or more, more preferably 100,000 or more, and even more preferably 300,000 or more. The weight-average molecular weight (Mw) of the (meth)acrylic copolymer is preferably 1,500,000 (1.5 million) or less, and more preferably 1,000,000 (1 million) or less. In this specification, the weight-average molecular weight (Mw) is the value on a standard polystyrene basis, measured by gel permeation chromatography (GPC).

[0049] The (meth)acrylic copolymer is preferably a (meth)acrylic acid ester polymer (hereinafter sometimes referred to as "energy-ray curable polymer") in which an energy-ray curable functional group (energy-ray curable group) is introduced into the side chain.

[0050] • Energy-curable polymer The energy-ray curable polymer is preferably a copolymer obtained by reacting a (meth)acrylic copolymer having a functional group-containing monomer unit with an unsaturated group-containing compound having a functional group that bonds to the functional group of the (meth)acrylic copolymer.

[0051] The (meth)acrylic copolymer preferably contains structural units derived from functional group-containing monomers and structural units derived from (meth)acrylic acid ester monomers or derivatives of (meth)acrylic acid ester monomers.

[0052] The functional group-containing monomer used as a constituent unit of the (meth)acrylic copolymer is preferably a monomer having a polymerizable double bond and a functional group within its molecule. The functional group is preferably at least one of the functional groups selected from the group consisting of a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, and an epoxy group.

[0053] Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Hydroxyl group-containing monomers may be used individually or in combination of two or more.

[0054] Examples of carboxyl group-containing monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Carboxyl group-containing monomers may be used individually or in combination of two or more.

[0055] Examples of amino group-containing monomers or substituted amino group-containing monomers include aminoethyl (meth)acrylate and n-butylaminoethyl (meth)acrylate. The amino group-containing monomer or substituted amino group-containing monomer may be used individually or in combination of two or more types.

[0056] As the (meth)acrylic acid ester monomers constituting the (meth)acrylic copolymer, alkyl (meth)acrylates having 1 to 20 carbon atoms in the alkyl group are preferred, as well as monomers having an alicyclic structure in the molecule (alicyclic structure-containing monomers).

[0057] As the alkyl (meth)acrylate, alkyl (meth)acrylates in which the number of carbon atoms in the alkyl group is 1 or more and 18 or less are preferred. More preferred alkyl (meth)acrylates include, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. Alkyl (meth)acrylates may be used individually or in combination of two or more.

[0058] Preferred monomers containing alicyclic structures include, for example, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. The alicyclic structure-containing monomers may be used individually or in combination of two or more.

[0059] Furthermore, the (meth)acrylic copolymer preferably contains the constituent units derived from the above-mentioned functional group-containing monomers in a proportion of 1% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more. The (meth)acrylic copolymer preferably contains the constituent units derived from the above-mentioned functional group-containing monomer in an amount of 35% by mass or less, more preferably 30% by mass or less, and even more preferably 25% by mass or less.

[0060] Furthermore, the (meth)acrylic copolymer preferably contains structural units derived from (meth)acrylic acid ester monomers or their derivatives in a proportion of 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The (meth)acrylic copolymer preferably contains constituent units derived from (meth)acrylic acid ester monomers or derivatives thereof in a proportion of 99% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0061] (Meth)acrylic copolymers can be obtained by copolymerizing a functional group-containing monomer as described above with a (meth)acrylic acid ester monomer or a derivative thereof using a conventional method. In addition to the monomers mentioned above, the (meth)acrylic copolymer may also contain at least one constituent unit selected from the group consisting of dimethylacrylamide, vinyl formate, vinyl acetate, and styrene.

[0062] By reacting a (meth)acrylic copolymer having the above-mentioned functional group-containing monomer units with an unsaturated group-containing compound having a functional group bonded to that functional group, an energy-ray curable polymer can be obtained.

[0063] The functional group of the unsaturated group-containing compound can be appropriately selected according to the type of functional group of the functional group-containing monomer unit of the (meth)acrylic copolymer. For example, if the functional group of the (meth)acrylic copolymer is a hydroxyl group, an amino group, or a substituted amino group, the functional group of the unsaturated group-containing compound is preferably an isocyanate group or an epoxy group. If the functional group of the (meth)acrylic copolymer is an epoxy group, the functional group of the unsaturated group-containing compound is preferably an amino group, a carboxyl group, or an aziridinyl group.

[0064] The unsaturated group-containing compound contains at least one energy-ray polymerizable carbon-carbon double bond per molecule, preferably between one and six, and more preferably between one and four.

[0065] Examples of compounds containing unsaturated groups include 2-methacryloyloxyethyl isocyanate (2-isocyanatoethyl methacrylate), meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; acryloyl monoisocyanate compounds obtained by the reaction of a diisocyanate compound or polyisocyanate compound with hydroxyethyl (meth)acrylate; acryloyl monoisocyanate compounds obtained by the reaction of a diisocyanate compound or polyisocyanate compound with a polyol compound with hydroxyethyl (meth)acrylate; glycidyl (meth)acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, and the like.

[0066] The unsaturated group-containing compound is preferably used in a proportion (addition rate) of 50 mol% or more, more preferably 60 mol% or more, and even more preferably 70 mol% or more, relative to the number of moles of the functional group-containing monomer of the (meth)acrylic copolymer. The unsaturated group-containing compound is preferably used in a proportion (addition rate) of 95 mol% or less, more preferably 93 mol% or less, and even more preferably 90 mol% or less, relative to the number of moles of the functional group-containing monomer of the (meth)acrylic copolymer.

[0067] In the reaction between a (meth)acrylic copolymer and an unsaturated group-containing compound, the reaction temperature, pressure, solvent, time, presence or absence of a catalyst, and type of catalyst can be appropriately selected depending on the combination of functional groups of the (meth)acrylic copolymer and the unsaturated group-containing compound. As a result, the functional groups of the (meth)acrylic copolymer and the functional groups of the unsaturated group-containing compound react, introducing unsaturated groups into the side chains of the (meth)acrylic copolymer, and yielding an energy-ray curable polymer.

[0068] The weight-average molecular weight (Mw) of the energy-ray curable polymer is preferably 50,000 or more, more preferably 100,000 or more, and even more preferably 300,000 or more. The weight-average molecular weight (Mw) of the energy-ray curable polymer is preferably 1,500,000 (1.5 million) or less, and more preferably 1,000,000 (1 million) or less.

[0069] [Photopolymerization initiator] When the adhesive composition contains a photocurable compound, specifically an ultraviolet-curable compound (e.g., an ultraviolet-curable resin), it is preferable that the adhesive composition also contains a photopolymerization initiator. By including a photopolymerization initiator in the adhesive composition, the polymerization curing time and the amount of light irradiation can be reduced.

[0070] Specific examples of photopolymerization initiators include, for example, benzoin compounds, acetophenone compounds, acyl phosphinoxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds. Furthermore, photosensitizers such as amines or quinones can also be used as photopolymerization initiators.

[0071] More specific examples of photopolymerization initiators include, for example, 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzylphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyrolnitrile, dibenzyl, diacetyl, 8-chloranthraquinone, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. Photopolymerization initiators may be used individually or in combination of two or more.

[0072] The photopolymerization initiator is preferably used in an amount of 0.01 parts by mass or more, more preferably 0.03 parts by mass or more, and even more preferably 0.05 parts by mass or more, per 100 parts by mass of the adhesive resin which is in any of the embodiments of (I), (II), or (III) above. The photopolymerization initiator is preferably used in an amount of 10 parts by mass or less, and more preferably in an amount of 5 parts by mass or less, per 100 parts by mass of the adhesive resin which is any of the embodiments described in (I), (II), or (III) above.

[0073] When the photopolymerization initiator contains a (meth)acrylic copolymer and an energy ray curable compound as the adhesive resin, it is preferable to use an amount of 0.1 parts by mass or more, and more preferably 0.5 parts by mass or more, per 100 parts by mass of the energy ray curable compound. When the photopolymerization initiator contains a (meth)acrylic copolymer and an energy ray curable compound as the adhesive resin, it is preferable to use an amount of 10 parts by mass or less, and more preferably 6 parts by mass or less, per 100 parts by mass of the energy ray curable compound.

[0074] [Crosslinking agent] The adhesive composition may contain a crosslinking agent. As the crosslinking agent, a polyfunctional compound that has reactivity with functional groups of (meth)acrylic copolymers, etc., can be used. Examples of polyfunctional compounds in the adhesive composition include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, and reactive phenolic resins.

[0075] In the case of the adhesive resin according to the embodiment of (I) above, the amount of crosslinking agent is preferably 0.01 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of the (meth)acrylic copolymer. In the case of the adhesive resin according to the embodiment of (I) above, the amount of crosslinking agent is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of (meth)acrylic copolymer.

[0076] In the case of the adhesive resin according to the embodiment of (II) above, the amount of crosslinking agent is preferably 0.01 parts by mass or more, and more preferably 0.1 parts by mass or more, per 100 parts by mass of the polymer in which unsaturated groups have been introduced into the side chains of the non-energy ray curable polymer. In the case of the adhesive resin according to the embodiment (II) above, the amount of crosslinking agent is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the polymer in which unsaturated groups have been introduced into the side chains of the non-energy ray curable polymer.

[0077] In the case of the adhesive resin according to the above embodiment (III), the amount of crosslinking agent is preferably 0.01 parts by mass or more, and more preferably 0.1 parts by mass or more, per 100 parts by mass of the polymer in which unsaturated groups have been introduced into the side chains of the non-energy ray curable polymer. In the case of the adhesive resin according to the embodiment of (III) above, the amount of crosslinking agent is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, per 100 parts by mass of the polymer in which unsaturated groups have been introduced into the side chains of the non-energy ray curable polymer.

[0078] The adhesive composition may also contain other components besides those listed above, such as antistatic agents, antioxidants, plasticizers, fillers, rust inhibitors, pigments, and dyes.

[0079] From the viewpoint of uniformity of the adhesive layer and suppression of variations in adhesive strength, the thickness of the adhesive layer is preferably, for example, 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. In a similar view, the thickness of the adhesive layer is preferably 70 μm or less, more preferably 50 μm or less, even more preferably 30 μm or less, and even more preferably 10 μm or less.

[0080] <Release film> The release film is not particularly limited as long as it can be peeled off the adhesive layer after being attached to it. Preferably, the release film comprises, for example, a release substrate and a release agent layer provided on the release substrate. When the release film comprises a release agent layer provided on the release substrate, the side of the release agent layer opposite to the release substrate side is the side that contacts the adhesive surface of the adhesive layer.

[0081] The release substrate preferably contains a resin. Examples of resins included in the release substrate include polyolefin resins (polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymer, norbornene resin, and ethylene copolymers (ethylene-vinyl acetate copolymer, ethylene-(meth)acrylic acid copolymer, and ethylene-(meth)acrylic acid ester copolymer, etc.)), polyester resins (polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate, etc.), polyvinyl chloride resins (polyvinyl chloride and vinyl chloride copolymer, etc.), polyurethane, polystyrene, polycarbonate, polyamide, polyimide, and fluororesin. Among these, from the viewpoint of heat resistance, the resin constituting the release substrate is preferably a polyester resin such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate.

[0082] In addition to the resin, the release agent may contain various additives as needed, such as antioxidants, ultraviolet absorbers, light stabilizers, antistatic agents, inorganic or organic fillers, and plasticizers.

[0083] The release substrate can be obtained by known methods. For example, the substrate can be made by molding a resin composition containing a resin and additives as needed using methods such as casting, calendering, T-die extrusion, or inflation. Specifically, for example, the release substrate can be obtained by melt-extruding a resin composition containing a resin to form an unstretched film, and then using sequential biaxial stretching or simultaneous biaxial stretching to obtain the molded unstretched film.

[0084] Examples of release agents included in the release agent layer include silicone resins, alkyd resins, acrylic resins, long-chain alkyl resins, unsaturated polyester resins, polyolefin resins, and waxes. Among these, it is preferable to use a silicone resin as the release agent in the release agent layer. Examples of silicone resins include silicone resins with a dimethylpolysiloxane basic skeleton. Examples of silicone resins include addition reaction type, condensation reaction type, ultraviolet curing type, and electron beam curing type. When using an addition reaction type silicone resin as the release agent, it is preferable to use a crosslinking agent and a catalyst in combination. Examples of crosslinking agents include organopolysiloxanes having hydrogen atoms bonded to at least two silicon atoms in one molecule. Examples of catalysts include metal compounds of platinum, palladium, and rhodium.

[0085] The paint stripper composition containing the paint stripper may optionally contain various additives such as antioxidants, UV absorbers, inorganic or organic fillers, antistatic agents, and surfactants.

[0086] The release film can be obtained, for example, by preparing a coating solution by mixing an organic solvent such as toluene, ethyl acetate, methyl ethyl ketone, hexane, and heptane with a release agent composition, applying the coating solution to the release substrate using a known coating method, and then drying and heating it.

[0087] The thickness of the release sheet is not particularly limited. For example, the thickness of the release sheet is preferably 10 μm or more, and more preferably 20 μm or more. The thickness of the release sheet is preferably 200 μm or less, and more preferably 150 μm or less. The thickness of the release substrate and the thickness of the release agent layer are not particularly limited. For example, the thickness of the release substrate is preferably 3 μm or more, and more preferably 5 μm or more. The thickness of the release substrate is preferably 50 μm or less, and more preferably 40 μm or less. For example, the thickness of the release agent layer is preferably 0.01 μm or more, and more preferably 0.03 μm or more. The thickness of the release agent layer is preferably 2.0 μm or less, and more preferably 1.0 μm or less.

[0088] In this embodiment, the maximum cross-sectional height St of the adhesive layer side (release surface) of the release film is 0.45 μm or more, and the root mean square height Sq is 17.5 nm or more. The maximum cross-sectional height St is preferably 0.5 μm or more, and more preferably 0.55 μm or more, from the viewpoint of making it easier to suppress the occurrence of orange peel. The upper limit of the maximum cross-sectional height St is not particularly limited. From the viewpoint of making it easier to suppress the occurrence of orange peel, it may be, for example, 0.9 μm or less, or 0.7 μm or less.

[0089] The root mean square height Sq is preferably 17.7 nm or greater, more preferably 20.0 nm or greater, and even more preferably 25.0 nm or greater, from the viewpoint of making it easier to suppress the occurrence of yuzu peel. The upper limit of the root mean square height Sq is not particularly limited. From the viewpoint of making it easier to suppress the occurrence of yuzu peel, it may be, for example, 50 nm or less, or 40 nm or less.

[0090] The maximum cross-sectional height St is a parameter that extends the "maximum cross-sectional height Rt of the roughness curve," a surface texture parameter representing line roughness as defined in JIS B 0601:2013, into three dimensions. The root mean square height Sq is a surface texture parameter representing surface roughness as defined in JIS B 0681-2:2018. Hereinafter, when referring to the maximum cross-sectional height St and the root mean square height Sq collectively, the term "surface texture" may be used. The surface texture can be measured by the method described in the Examples section below.

[0091] The release film preferably contains a filler in order to make it easier to obtain the desired surface properties. Furthermore, the release film preferably contains a filler in order to improve the ease of dispensing the release film itself. Methods for adjusting the surface properties of the adhesive layer side of the release film include, for example, at least one of the methods described in (A) and (B) below. The surface properties of the adhesive layer side of the release film can be adjusted by the shape, particle size, and content of the filler, etc. (A) A method for impregnating the release substrate of a release film with an inorganic or organic filler. (B) A method for including an inorganic or organic filler in the release agent composition of the release agent layer.

[0092] It is preferable to adopt method (A) above because it makes it easier to obtain the desired surface properties. Furthermore, it is also preferable to adopt method (A) above because it minimizes the possibility of affecting the peeling force with respect to the adhesive layer. The following describes a method for adjusting the surface properties of the adhesive layer side of the release film using method (A) above.

[0093] When adopting method (A) above, the method of mixing the inorganic or organic filler with the resin is not particularly limited, and known methods can be used. For example, the methods shown in (A1) to (A3) below can be cited. (A1) A method of directly blending and kneading the filler and resin. (A2) A method of preparing a resin composition with a high concentration of filler and then diluting it with resin to achieve the desired filler content (the so-called masterbatch method). (A3) A method of preparing a raw material slurry by dispersing a filler in the raw materials of a resin, and adding the raw material slurry at any stage in the resin manufacturing process.

[0094] Among these methods, method (A3) is preferred because it makes it easier to obtain the desired surface properties. When the resin contained in the release substrate is, for example, polyethylene terephthalate, an ethylene glycol slurry is prepared by dispersing a filler in ethylene glycol, which is the raw material. Then, for example, after the esterification or transesterification reaction is completed and before the polycondensation reaction begins, the ethylene glycol slurry is added and the polycondensation reaction is carried out to obtain polyethylene terephthalate containing the filler.

[0095] A release film having the desired surface properties can be obtained, for example, by forming a resin mixed with a filler by any of the methods described in (A1), (A2), or (A3) above into a film using the known method described above to obtain a release substrate, and then providing a release agent layer on the obtained release substrate.

[0096] Examples of inorganic fillers include silica particles, alumina particles, calcium carbonate particles, kaolin particles, magnesium carbonate particles, magnesium silicate particles, aluminum silicate particles, and titanium dioxide particles. Examples of organic fillers include cross-linked polystyrene particles, cross-linked acrylic particles, and organic silicone particles. These organic or inorganic fillers may be used individually or in combination of two or more. Among these exemplified inorganic or organic fillers, the use of inorganic fillers is preferred. The following describes the case in which inorganic fillers are used.

[0097] Among the inorganic fillers exemplified above, silica particles are preferred as the inorganic filler because they make it easier to obtain the desired surface properties. Spherical silica particles are even more preferred because they make it even easier to obtain the desired surface properties. The spherical silica particles may be porous particles with a porous surface, or non-porous particles with a non-porous surface.

[0098] In terms of making it easier to obtain the desired surface properties, the average particle size of the inorganic filler is preferably 4 μm or more, more preferably 5 μm or more, even more preferably 8 μm or more, and still more preferably 10 μm or more. Similarly, the average particle size of the inorganic filler is preferably 30 μm or less, more preferably 25 μm or less, and even more preferably 20 μm or less. The average particle size of the inorganic filler is the average particle size based on volume and can be measured by laser light scattering or by burning the resin component and observing and measuring the remaining inorganic material with an electron microscope.

[0099] In terms of making it easier to obtain the desired surface properties, the inorganic filler content is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, and more preferably 0.3 parts by mass or more, relative to the total resin contained in the release substrate. Similarly, the inorganic filler content is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, relative to the total resin contained in the release substrate.

[0100] [Method for manufacturing adhesive sheets for workpiece processing] An example of a preferred method for manufacturing the adhesive sheet for workpiece processing according to this embodiment will be described. The method for manufacturing the adhesive sheet for workpiece processing is not particularly limited. Preferably, the method for manufacturing the adhesive sheet for workpiece processing includes the steps of: preparing a base material, an adhesive composition, and a release film; applying the adhesive composition to the release surface (release treatment surface) of the release film to provide an adhesive layer formed from the adhesive composition; and laminating the base material on the side of the adhesive layer opposite to the release film side. The base material, adhesive composition, and release film can be the base material, adhesive composition, and release film that have already been described, respectively. A method for applying the above adhesive composition includes preparing a coating solution containing the adhesive composition and, if necessary, a solvent or dispersion medium, and applying the coating solution. The coating method is not particularly limited, and examples include the spin coating method, spray coating method, bar coating method, knife coating method, roll coating method, roll knife coating method, blade coating method, die coating method, gravure coating method, etc.

[0101] Examples of the solvents or dispersion media mentioned above include aromatic hydrocarbon solvents (benzene, toluene, etc.), ester solvents (ethyl acetate, butyl acetate, etc.), ketone solvents (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), aliphatic hydrocarbon solvents (n-pentane, n-hexane, n-heptane, etc.), and alicyclic hydrocarbon solvents (cyclopentane, cyclohexane, etc.). These solvents or dispersion media may be used individually or in combination of two or more.

[0102] The adhesive layer can be formed by applying a coating solution containing an adhesive composition to form a coating film, and then heating and drying the coating film.

[0103] The method for manufacturing the adhesive sheet for workpiece processing according to this embodiment is not limited to the above, and may also include the steps of: preparing a base material, an adhesive composition, and a release film; laminating the adhesive composition on the base material to form an adhesive layer; and laminating the release surface of the release film on the side of the adhesive layer opposite to the base material side.

[0104] If the adhesive composition contains a crosslinking agent, it is preferable to form a crosslinked structure in the adhesive layer by, for example, changing the drying conditions (temperature, time, etc.) of the coating film to which the coating liquid containing the adhesive composition has been applied, or by providing a heat treatment other than drying. The process may also include a step of seasoning the adhesive sheet for workpiece processing obtained by the above steps. Examples of seasoning conditions include leaving the sheet undisturbed for a period of 3 to 14 days (for example, 7 days) in an environment with a temperature of 20°C or higher and 50°C or lower (e.g., 23°C) and a relative humidity of 20% RH or higher and 50% RH or lower (e.g., 50% RH).

[0105] [How to use adhesive sheets for workpiece processing] The shape of the adhesive sheet for workpiece processing according to this embodiment is not particularly limited, as long as it comprises a base material, an adhesive layer provided on the surface of the base material, and a release film provided on the side of the adhesive layer opposite to the base material. The adhesive sheet for workpiece processing can take any shape, such as tape or label.

[0106] The adhesive sheet for workpiece processing according to this embodiment can be used as an adhesive sheet when processing a workpiece. After attaching the workpiece to the adhesive layer of the adhesive sheet for workpiece processing, various processing is performed on the workpiece while it is attached to the adhesive layer of the adhesive sheet for workpiece processing. Examples of workpieces to be attached to the adhesive layer include semiconductor components such as semiconductor wafers and semiconductor packages, and transparent components such as glass substrates and glass plates. The semiconductor wafer may be, for example, a silicon wafer or a compound semiconductor wafer such as gallium arsenide. The transparent component is not limited to glass and is a concept that includes transparent components that transmit light rays, for example, components that exhibit a visible light transmittance of 50% or more. The transparent component is preferably glass (glass substrate, glass plate, etc.).

[0107] The workpiece may have a surface with an arithmetic mean roughness Ra of 0.006 μm or less. If the workpiece has a surface with an arithmetic mean roughness Ra of 0.006 μm or less, it is preferable to attach the surface of the workpiece with an arithmetic mean roughness Ra of 0.006 μm or less to the adhesive layer. It is more preferable that the arithmetic mean roughness Ra is 0.005 μm or less. The lower limit of the arithmetic mean roughness Ra is not particularly limited, and for example, it may be 0.0001 μm or more.

[0108] The adhesive sheet for workpiece processing according to this embodiment is specifically applied as at least one selected from the group consisting of, for example, a backgrinding sheet, a dicing sheet, an expandable sheet, and a pickup sheet. The adhesive sheet for workpiece processing is preferably used in a process in which, for example, a workpiece is attached to an adhesive layer after peeling off a release film, the workpiece is diced into individual pieces while attached to the adhesive layer, and the individual pieces of the workpiece are peeled off from the adhesive layer. In this respect, the adhesive sheet for workpiece processing is preferably a dicing sheet.

[0109] When a workpiece processing adhesive sheet is used, for example, as a dicing sheet, specifically, a workpiece (e.g., a semiconductor wafer, semiconductor package, glass substrate, or glass plate) is attached to the adhesive layer of the workpiece processing adhesive sheet, and then dicing is performed. The processed workpiece, after dicing, is picked up from the adhesive layer of the workpiece processing adhesive sheet. If the adhesive layer contains an energy-ray curable adhesive, the adhesive layer of the workpiece processing adhesive sheet attached to the processed workpiece may be cured by irradiating it with energy rays (e.g., ultraviolet light), and then the processed workpiece may be picked up from the cured adhesive layer.

[0110] When the workpiece is a transparent material (e.g., a glass substrate and a glass plate), the processed workpiece (e.g., a glass chip) is required to have high transparency. The adhesive sheet for workpiece processing according to this embodiment suppresses the occurrence of orange peel texture. Therefore, by processing a transparent material using the adhesive sheet for workpiece processing according to this embodiment, high transparency can be ensured in the processed transparent material. Specifically, for example, the adhesive sheet for workpiece processing according to this embodiment can be applied as a dicing sheet to dice a glass substrate or a glass plate.

[0111] [Semiconductor devices and methods for manufacturing semiconductor devices] The semiconductor device according to this embodiment is manufactured using the adhesive sheet for workpiece processing according to this embodiment. The semiconductor device according to this embodiment is not particularly limited as long as it is obtained using the adhesive sheet for workpiece processing according to this embodiment. For example, in the method of using the adhesive sheet for workpiece processing described above, if the workpiece is a semiconductor material, the semiconductor device according to this embodiment is obtained.

[0112] A semiconductor device using the adhesive sheet for workpiece processing according to this embodiment (i.e., a semiconductor device manufactured using the adhesive sheet for workpiece processing according to this embodiment) can be obtained, for example, specifically, by a method for manufacturing a semiconductor device that includes the steps of: grinding the surface of a semiconductor wafer; attaching the ground surface of the semiconductor wafer to the surface of the adhesive layer of the adhesive sheet for workpiece processing according to this embodiment; obtaining semiconductor chips by separating the semiconductor wafer into individual pieces while it is attached to the adhesive sheet for workpiece processing; and separating the individual pieces of semiconductor chips from the adhesive sheet for workpiece processing according to this embodiment. The adhesive sheet for workpiece processing according to this embodiment can also be used in multiple steps of the method for manufacturing a semiconductor device. Furthermore, if the adhesive sheet for workpiece processing has an energy ray curable adhesive layer, an energy ray irradiation step is included after the workpiece piece formation step and before the step of separating from the sheet. In this manufacturing method, in the step of grinding the surface of the semiconductor wafer, the surface of the semiconductor wafer may be ground using another adhesive sheet for workpiece processing according to this embodiment. Furthermore, in the step of separating the individual semiconductor wafers from the adhesive sheet for workpiece processing according to this embodiment, another adhesive sheet for workpiece processing according to this embodiment may be used to separate the individual semiconductor wafers from the adhesive sheet for workpiece processing according to this embodiment.

[0113] Furthermore, a semiconductor device using the adhesive sheet for workpiece processing according to this embodiment can also be obtained by a method for manufacturing a semiconductor device, which includes, for example, the steps of: obtaining a seal by sealing a plurality of semiconductor elements placed on a substrate so as to cover them; attaching the seal to the adhesive layer of the adhesive sheet for workpiece processing according to this embodiment; separating the seal attached to the adhesive sheet for workpiece processing according to this embodiment into individual pieces; and separating the individual pieces of the seal from the adhesive sheet for workpiece processing according to this embodiment. In addition, if the adhesive sheet for workpiece processing has an energy ray curable adhesive layer, an energy ray irradiation step is included after the workpiece piece formation step and before the step of separating from the sheet. In this manufacturing method, in the step of separating the individual pieces of the seal from the adhesive sheet for workpiece processing according to this embodiment, another adhesive sheet for workpiece processing according to this embodiment may be used to separate the individual pieces of the seal from the adhesive sheet for workpiece processing according to this embodiment.

[0114] Furthermore, in addition to the above, the semiconductor device using the adhesive sheet for workpiece processing according to this embodiment may have known processes such as a rewiring process and a terminal formation process as additional processes.

[0115] [Variations of the Embodiment] The present invention is not limited in any way to the embodiments described above. The present invention includes modified forms of the embodiments described above, to the extent that the object of the present invention can be achieved. For example, the adhesive sheet 100 for workpiece processing shown in Figures 1 and 2 was described in an embodiment comprising an adhesive layer 20 and a release film 30 provided on the first surface 10A of a substrate. The adhesive sheet for workpiece processing according to this embodiment is not limited thereto, and adhesive layers and release films may be provided on both sides of the substrate. [Examples]

[0116] The present invention will be described in more detail below with reference to examples. The present invention is not limited in any way to these examples.

[0117] The measurements or evaluations in the following examples and comparative examples were performed by the methods described below.

[0118] [Surface roughness evaluation] (Surface properties of the release film surface) The maximum cross-sectional height (St) and root mean square height (Sq) were measured on the surface of the release film that is in contact with the adhesive layer (release surface) using a non-contact surface measurement system. The non-contact surface measurement system used was the "Vertscan" system manufactured by Hitachi High-Tech Science Corporation, which employs two-beam interferometry using direct phase detection interferometry, also known as Michelson interference. The surface properties of the release film were measured using a sample size of 3 cm × 3 cm, with n=1 (i.e., only one sample was used for evaluation). The maximum cross-sectional height (St) and root mean square height (Sq) were measured in accordance with ISO 25178.

[0119] [Yuzu Skin Evaluation] Tape-shaped samples for evaluating the orange peel texture were taken from the adhesive sheets for workpiece processing obtained in the examples and comparative examples. The evaluation sample is an adhesive sheet for workpiece processing with a three-layer structure in which a base material, adhesive layer, and release film are laminated in that order. The outer surface of the release film on the sample (the side opposite to the adhesive layer) was in contact with a black acrylic plate (manufactured by Mitsubishi Chemical Corporation) and the end of the sample was fixed with double-sided tape. Then, fluorescent light was shone onto the sample from the base material side, and the incident light was reflected off the black acrylic plate. The evaluation sample was observed from the base material side, and the distortion of the reflected fluorescent light image was judged according to the following criteria.

[0120] <Evaluation Criteria> A(〇): There is no distortion of the fluorescent light image reflected on the substrate, and the occurrence of orange peel is completely suppressed. F(×): The image of the fluorescent light reflected on the substrate appears distorted, and an orange peel texture is present.

[0121] [Example 1] (1) Preparation of adhesive composition 40 parts by mass of 2-ethylhexyl acrylate (2EHA), 50 parts by mass of methacrylic acid (MA), and 10 parts by mass of acrylic acid (AA) were polymerized by solution polymerization to obtain an acrylic acid ester copolymer (weight-average molecular weight (Mw): 500,000). To this, 7 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyo Chem Co., Ltd., product name "BHS-8518") as a crosslinking agent, 90 parts by mass of UV-curable resin (manufactured by Mitsubishi Chemical Corporation, Shikou UV-5806, weight-average molecular weight (Mw): 1700, polyfunctional urethane acrylate, number of functional groups: approximately 10 functions), and 1 part by mass of OMNIRAD184 (manufactured by BASF) as a photopolymerization initiator were mixed and diluted with methyl ethyl ketone to obtain a coating solution of an adhesive composition with a solid content of 30% by mass.

[0122] (2) Preparation of release film 100 parts by mass of terephthalic acid and 45 parts by mass of ethylene glycol were charged into an ester reaction vessel equipped with a stirrer, a heating device, and a distillate separation column, and heated to 250°C to melt the terephthalic acid. Next, to 100 parts by mass of the obtained polyethylene terephthalate (hereinafter, polyethylene terephthalate may be referred to as PET), an ethylene glycol solution of antimony trioxide was added so that the amount of antimony trioxide added was 0.02 parts by mass. Subsequently, the mixture was stirred and maintained under atmospheric pressure for 4 hours while the water was distilled off to carry out the esterification reaction, effectively completing the esterification reaction and yielding a low-molecular-weight PET polymer (hereinafter referred to as PET oligomer). The resulting PET oligomer was transferred to a polycondensation reactor equipped with a stirrer and a distillation tube. To the PET oligomer after transfer, a particle ethylene glycol slurry (particle type: Sunsphere H-201, manufactured by AGC SI-TEC, average particle size 20 μm), which consists of spherical porous silica particles dispersed in ethylene glycol, was added as a filler in an amount of 0.6 parts by mass of particles per 100 parts by mass of the resulting PET. Furthermore, magnesium acetate was added, with an ethylene glycol solution of magnesium acetate tetrahydrate added to 100 parts by mass of the resulting PET, so that the amount of magnesium acetate added was 0.03 parts by mass. Subsequently, an ethylene glycol solution of ethyl acid phosphate was added to the PET oligomer as a heat stabilizer, and an ethylene glycol solution of antimony trioxide was added as a polycondensation catalyst. Subsequently, the pressure was reduced from 101.3 kPa to 0.4 kPa over 85 minutes and maintained at 0.4 kPa. At the same time, the temperature was increased from 250°C to 280°C over 1 hour and 55 minutes, and held at 280°C for 2.5 hours to carry out the melt polycondensation reaction. After the reaction was complete, the material was extracted in strand form and cut while being cooled with water to obtain pellet-shaped PET(A). The ethylene glycol solution of ethyl acid phosphate was added in an amount of 0.0202 parts by mass of ethyl acid phosphate per 100 parts by mass of the obtained PET. The ethylene glycol solution of antimony trioxide was added in an amount of 0.02 parts by mass of antimony trioxide per 100 parts by mass of the obtained PET. PET(A) was extruded using a twin-screw extruder and biaxially stretched to obtain a PET film with a thickness of 38 μm. This PET film was used as a release substrate.

[0123] 100 parts by mass of an addition-reaction type silicone resin release agent (manufactured by Toray Dow Corning Silicone Co., Ltd., product name: SRX-211), whose main component is a polydimethylsiloxane having vinyl groups as functional groups and a crosslinking agent (polymethylhydrogensiloxane), were mixed with 1.8 parts by mass of a platinum-based catalyst (manufactured by Toray Dow Corning Silicone Co., Ltd., product name: SRX-212). Furthermore, 0.1 parts by mass of benzyldimethylacetal, an α-diketone dialkylacetal, was added per 100 parts by mass of the main component as a photosensitizer. Subsequently, the mixture was diluted with an organic solvent mainly composed of toluene to prepare a coating solution with a solid content concentration of 1% by mass.

[0124] This coating solution is applied to the surface of the 38 μm thick biaxially oriented PET film obtained above, with a dry thickness of 0.1 μm (solid content coating amount: 0.1 g / m²). 2 The coating was applied in a nearly uniform manner using the gravure coating method to achieve the desired result. Next, the material was heated in a 50°C hot air circulating dryer for 20 seconds. Immediately afterward, it was irradiated with ultraviolet light at a conveyor-type ultraviolet irradiation machine (using a high-diffusion type heat-cut filter) equipped with one electrodeless ultraviolet lamp (using an H bulb, lamp output 240 W / cm) manufactured by Fusion Corporation, at a conveyor speed of 200 m / min, to cure the silicone resin release agent in the coating liquid and form a release agent layer. In this way, a release film with a release agent layer formed on the release substrate was produced. The release film produced in Example 1 is denoted as SP1 in Table 1.

[0125] (3) Preparation of adhesive sheets for workpiece processing A coating solution of the adhesive composition prepared in (1) above was applied to the release-treated surface of the release film prepared in (2) above, and dried by heating to form an adhesive layer with a thickness of 10 μm on the release film. A polyethylene terephthalate film (thickness: 100 μm, maximum cross-sectional height Rt = 0.43 μm) was prepared as the base material. At least one side of this base material was treated for easy adhesion. The side of the base material with the easy-adhesion treatment was attached to the side of the release film that had the adhesive layer formed on it, to obtain an adhesive sheet for workpiece processing consisting of the base material, the adhesive layer, and the release film.

[0126] [Example 2] A workpiece adhesive sheet was prepared in the same manner as in Example 1, except that the particles in the ethylene glycol slurry used in the preparation of the release film in Example 1 (2) were changed to silica particles (particle type: Sunsphere H-51, manufactured by AGC SI-TEC, average particle size 5 μm) according to Example 2. The release film prepared in Example 2 is denoted as SP2 in Table 1.

[0127] [Comparative Example 1] In Example 1, a release film was prepared in the same manner as in (2) above, except that the particles in the ethylene glycol slurry used in the preparation of the release film in (2) above were changed to silica particles (particle type: Sunsphere H-31, manufactured by AGC SI-TEC, average particle size 3 μm) as in Comparative Example 1. The release film prepared in Comparative Example 1 is denoted as SP3 in Table 1. Then, an adhesive sheet for workpiece processing was prepared in the same manner as in Example 1, except that the polyethylene terephthalate film (thickness: 100 μm, maximum cross-sectional height Rt = 0.43 μm) used in the preparation of the adhesive sheet for workpiece processing described in (3) above was changed to a polyethylene terephthalate film (thickness: 50 μm, maximum cross-sectional height Rt = 0.43 μm).

[0128] [Table 1]

[0129] In each example, the maximum cross-sectional height St and root mean square height Sq were higher than in the comparative example, no orange peel texture occurred, and the evaluation results were favorable. The adhesive sheets for workpiece processing obtained in each example showed that the occurrence of orange peel texture on the adhesive layer on the side opposite to the substrate side was suppressed. [Explanation of symbols]

[0130] 10...Base material, 10A...First surface of base material, 10B...Second surface of base material, 20...Adhesive layer, 20A...First surface of adhesive layer, 20B...Second surface of adhesive layer, 30...Release film, 30A...First surface of release film, 30B...Second surface of release film, 100...Adhesive sheet for workpiece processing.

Claims

1. A workpiece processing adhesive sheet comprising a base material, an adhesive layer provided on one side of the base material, and a release film provided on the side of the adhesive layer opposite to the base material, The adhesive layer is made of an adhesive composition having energy ray curability. The adhesive composition comprises an energy-curable (meth)acrylic compound, an energy-curable (meth)acrylic copolymer different from the energy-curable (meth)acrylic compound, a crosslinking agent, and a photopolymerization initiator. The maximum cross-sectional height St of the adhesive layer side of the release film is 0.45 μm or more, and the root mean square height Sq is 17.5 nm or more. Adhesive sheet for workpiece processing.

2. In the adhesive sheet for workpiece processing according to claim 1, The release film contains a filler, Adhesive sheet for workpiece processing.

3. In the adhesive sheet for workpiece processing according to claim 1 or claim 2, The workpiece to be attached to the adhesive layer is a transparent material. Adhesive sheet for workpiece processing.

4. In the adhesive sheet for workpiece processing described in claim 3, The transparent member is glass. Adhesive sheet for workpiece processing.

5. In the adhesive sheet for workpiece processing according to any one of claims 1 to 4, The aforementioned adhesive sheet for workpiece processing is a dicing sheet. Adhesive sheet for workpiece processing.

6. A semiconductor device manufactured using the adhesive sheet for workpiece processing described in any one of claims 1 to 5.

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