Workpiece processing sheet

Abstract

To provide a work processing sheet capable of picking up well.SOLUTION: A work processing sheet includes a base material, and a pressure-sensitive adhesive layer laminated on one side of the base material, and the pressure-sensitive adhesive layer is composed of an active energy ray-curable pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing a non-halogen-based and non-metal ion-based ionic material.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a workpiece processing sheet used for processing a workpiece such as a semiconductor wafer. [Background technology]

[0002] Semiconductor wafers such as silicon and gallium arsenide and various packages are manufactured in large diameters, cut into chips (diced), peeled off (picked up), and then transferred to the next process, the mounting process. At this time, the workpieces such as semiconductor wafers are stacked on an adhesive sheet (hereinafter sometimes referred to as a "workpiece processing sheet") that has a base material and an adhesive layer, and then undergo processing such as backgrinding, dicing, cleaning, drying, expanding, picking up, and mounting.

[0003] As examples of the above-mentioned workpiece processing sheets, Patent Documents 1 to 3 disclose workpiece processing sheets having an adhesive layer containing a predetermined component. In particular, Patent Document 1 discloses a workpiece processing sheet having an adhesive layer containing a predetermined amount of polypropylene glycol having a predetermined number-average molecular weight (paragraph 0084 of Patent Document 1, etc.). Patent Document 2 discloses a workpiece processing sheet having an adhesive layer containing a predetermined polypropylene oxide (claim 1 of Patent Document 2, etc.). Furthermore, Patent Document 3 discloses a workpiece processing sheet having an adhesive layer containing a predetermined polyoxypropylene-glyceryl ether (paragraph 0041 of Patent Document 3, etc.), polyoxypropylene-diglyceryl ether (paragraph 0044 of Patent Document 3, etc.), or polyoxypropylene-sorbitol (paragraph 0045 of Patent Document 3, etc.). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4931519 [Patent Document 2] Patent No. 5764518 [Patent Document 3] Patent No. 5764519 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned pickup process, the chip is generally pushed up from the back side of the chip through the workpiece processing sheet, and then picked up while being sucked up by a vacuum collet. In this case, from the viewpoint of efficiency and preventing chip damage, it is preferable to be able to pick up the chip without excessive pushing up or excessive suction. In particular, in recent years, as workpieces have become thinner and chip sizes have become smaller, there has been a demand for better pickup performance. However, conventional workpiece processing sheets such as those disclosed in Patent Documents 1 to 3 cannot fully meet these pickup requirements.

[0006] The present invention has been made in view of the above circumstances, and has as its object to provide a workpiece processing sheet that allows for good pickup. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, first, the present invention provides a workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, characterized in that the adhesive layer is composed of an active energy ray-curable adhesive formed from an adhesive composition containing a non-halogen and non-metal ion-based ionic material (Invention 1).

[0008] The workpiece processing sheet according to the above invention (Invention 1) has an adhesive layer made of an active energy ray-curable adhesive formed from an adhesive composition containing the above-mentioned ionic material, so that the adhesion of the workpiece processing sheet to the chips is appropriately reduced when the chips are picked up. This makes it possible to easily pick up the chips with the workpiece processing sheet without the need for excessive pushing up or excessive suction by a vacuum collet.

[0009] In the above invention (Invention 1), the anion constituting the ionic material is preferably a sulfonate-based anion (Invention 2).

[0010] In the above inventions (Inventions 1 and 2), the pressure-sensitive adhesive composition contains, in addition to the ionic material, at least one of an acrylic polymer (A) having an active energy ray-curable group introduced in its side chain and an acrylic polymer (B) having no active energy ray-curable group introduced in its side chain, and the content of the ionic material in the pressure-sensitive adhesive composition is preferably 0.01 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of the total amount of the acrylic polymer (A) and the acrylic polymer (B) (Invention 3).

[0011] In the above inventions (Inventions 1 to 3), the pressure-sensitive adhesive composition preferably contains an acrylic polymer (A) having an active energy ray-curable group introduced into the side chain, and the ionic material (Invention 4).

[0012] In the above inventions (Inventions 1 to 3), the pressure-sensitive adhesive composition preferably contains an acrylic polymer (B) having no active energy ray-curable groups introduced into its side chains, an active energy ray-curable component, and the ionic material (Invention 5).

[0013] In the above inventions (Inventions 1 to 5), the workpiece processing sheet is preferably used as at least one of a dicing sheet and a pickup sheet (Invention 6). [Effects of the Invention]

[0014] According to the workpiece processing sheet of the present invention, pickup can be performed satisfactorily. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described. The workpiece processing sheet according to this embodiment includes a substrate and an adhesive layer laminated on one side of the substrate.

[0016] 1. Components of workpiece processing sheets (1) Base material The substrate in this embodiment is not particularly limited as long as it exhibits the desired function when the workpiece processing sheet is used. In particular, the substrate is preferably a resin film primarily composed of a resin-based material. Specific examples include polyolefin-based films such as polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, and norbornene resin film; polyester-based films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate; ethylene-vinyl acetate copolymer film; ethylene-(meth)acrylic acid copolymer film, ethylene-methyl(meth)acrylate copolymer film, and other ethylene-(meth)acrylic acid ester copolymer films; polyvinyl chloride-based films such as polyvinyl chloride film and vinyl chloride copolymer film; (meth)acrylic acid ester copolymer film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; and fluororesin film. Modified films such as these crosslinked films and ionomer films can also be used. The substrate may also be a laminate film formed by laminating multiple of the above-mentioned films. In this laminated film, the materials constituting the layers may be the same or different.

[0017] Among the above, it is preferable to use at least one of a polyolefin film and an ethylene copolymer film, and it is particularly preferable to use an ethylene-(meth)acrylic acid copolymer film. In this specification, "(meth)acrylic acid" means both acrylic acid and methacrylic acid. The same applies to other similar terms. In this specification, "polymer" also includes the concept of "copolymer."

[0018] The substrate may contain various additives such as a flame retardant, a plasticizer, an antistatic agent, a lubricant, an antioxidant, a colorant, an infrared absorber, an ultraviolet absorber, an ion scavenger, etc. The content of these additives is not particularly limited, but is preferably set within a range in which the substrate exhibits the desired function.

[0019] The surface of the substrate on which the pressure-sensitive adhesive layer is to be laminated may be subjected to a surface treatment such as a primer treatment, a corona treatment, or a plasma treatment in order to enhance adhesion to the pressure-sensitive adhesive layer.

[0020] The thickness of the substrate can be set appropriately depending on the method for using the workpiece processing sheet, but is preferably 200 μm or less, particularly 150 μm or less, and is preferably 10 μm or more, particularly 25 μm or more.

[0021] (2) Adhesive layer As described above, the adhesive layer in this embodiment is composed of an active energy ray-curable adhesive formed from an adhesive composition containing a non-halogen and non-metal ion ionic material.

[0022] The workpiece processing sheet according to this embodiment allows for good pick-up because the adhesive layer is made of the above-described adhesive composition. In particular, the adhesive that makes up the adhesive layer is active energy ray-curable, so that the adhesive layer can be irradiated with active energy rays to effectively reduce the adhesive strength to the workpiece. Furthermore, the use of the above-described ionic material also moderately reduces the adhesion between the adhesive layer and the workpiece. As a result, the workpiece processing sheet according to this embodiment allows for easy pick-up of the workpiece, preventing damage to the workpiece and reduced production efficiency due to poor pick-up.

[0023] Preferred embodiments of the pressure-sensitive adhesive composition in this embodiment include a pressure-sensitive adhesive composition containing at least an acrylic polymer (A) having an active energy ray-curable group introduced into its side chain and an ionic material, and a pressure-sensitive adhesive composition containing at least an acrylic polymer (B) having no active energy ray-curable group introduced into its side chain, an active energy ray-curable component, and an ionic material. These components and other components that may be contained in the pressure-sensitive adhesive composition are described below.

[0024] (2-1) Acrylic polymer (A) having an active energy ray-curable group introduced into the side chain The acrylic polymer (A) having an active energy ray-curable group introduced into a side chain in the present embodiment (hereinafter may be referred to as "active energy ray-curable polymer (A)") is not particularly limited, and is preferably, for example, one obtained by reacting an acrylic copolymer (a1) having a functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group.

[0025] The acrylic copolymer (a1) preferably contains a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth)acrylic acid ester monomer or a derivative thereof.

[0026] The functional group-containing monomer as a constituent unit of the acrylic copolymer (a1) is preferably a monomer having a polymerizable double bond and a functional group such as a hydroxy group, a carboxy group, an amino group, a substituted amino group, or an epoxy group in the molecule.

[0027] Examples of hydroxy 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, which may be used alone or in combination of two or more.

[0028] Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, citraconic acid, etc. These may be used alone or in combination of two or more.

[0029] Examples of the amino group-containing monomer or substituted amino group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0030] When the acrylic copolymer (a1) contains the functional group-containing monomer, the mass proportion of the structural portion derived from the functional group-containing monomer in the acrylic copolymer (a1) is preferably 5% by mass or more, particularly preferably 10% by mass or more, and even more preferably 15% by mass or more. Furthermore, this proportion is preferably 45% by mass or less, particularly preferably 40% by mass or less, and even more preferably 35% by mass or less. By having the proportion of the structural portion derived from the functional group-containing monomer within the above range, it becomes easier to adjust the amount of the unsaturated group-containing compound (a2) introduced within a suitable range.

[0031] As the (meth)acrylic acid ester monomer constituting the acrylic copolymer (a1), alkyl (meth)acrylates in which the alkyl group has 1 to 20 carbon atoms, etc. are preferably used.

[0032] As the alkyl(meth)acrylate, alkyl(meth)acrylates in which the alkyl group has 1 to 18 carbon atoms, such as methyl(meth)acrylate, ethyl(meth)acrylate, propyl(meth)acrylate, n-butyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, etc., are particularly preferred. These may be used alone or in combination of two or more.

[0033] When the acrylic copolymer (a1) contains the (meth)acrylic acid ester monomer, the mass proportion of the structural portion derived from the (meth)acrylic acid ester monomer in the acrylic copolymer (a1) is preferably 55% by mass or more, particularly preferably 60% by mass or more, and even more preferably 65% ​​by mass or more. Furthermore, this proportion is preferably 95% by mass or less, particularly preferably 90% by mass or less, and even more preferably 85% by mass or less. By having the proportion of the structural portion derived from the (meth)acrylic acid ester monomer within the above range, the desired adhesive strength can be easily achieved.

[0034] The acrylic copolymer (a1) may contain components other than the monomers described above as constituent monomers, such as dimethylacrylamide, vinyl formate, vinyl acetate, styrene, and monomers having an alicyclic structure.

[0035] The active energy radiation-curable polymer (A) is obtained by reacting the acrylic copolymer (a1) having the functional group-containing monomer unit with the unsaturated group-containing compound (a2) having a functional group bonded to the functional group.

[0036] The functional group of the unsaturated group-containing compound (a2) can be appropriately selected depending on the type of functional group of the functional group-containing monomer unit of the acrylic copolymer (a1). For example, when the functional group of the acrylic copolymer (a1) is a hydroxy group, an amino group, or a substituted amino group, the functional group of the unsaturated group-containing compound (a2) is preferably an isocyanate group or an epoxy group, and when the functional group of the acrylic copolymer (a1) is an epoxy group, the functional group of the unsaturated group-containing compound (a2) is preferably an amino group, a carboxy group, or an aziridinyl group.

[0037] The unsaturated group-containing compound (a2) contains at least one, preferably 1 to 6, and more preferably 1 to 4 active energy ray-polymerizable carbon-carbon double bonds in one molecule. Specific examples of such unsaturated group-containing compounds (a2) include 2-(meth)acryloyloxyethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, (meth)acryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate; acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with a polyol compound and 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.

[0038] The amount of the unsaturated group-containing compound (a2) is preferably 40 mol % or more, particularly preferably 50 mol % or more, based on the amount of functional groups in the acrylic copolymer (a1). The amount of the unsaturated group-containing compound (a2) is preferably 99 mol % or less, particularly preferably 95 mol % or less, and even more preferably 90 mol % or less, based on the amount of functional groups in the acrylic copolymer (a1).

[0039] In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), 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 the functional groups of the acrylic copolymer (a1) and the unsaturated group-containing compound (a2). As a result, the functional groups present in the acrylic copolymer (a1) react with the functional groups in the unsaturated group-containing compound (a2), and the unsaturated groups are introduced into the side chains of the acrylic copolymer (a1), thereby obtaining an active-energy radiation-curable polymer (A).

[0040] In particular, the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2) is preferably carried out in the presence of at least one organometallic catalyst selected from organotin compounds, zirconium complexes, zinc complexes, and zirconium-containing metallic soaps. The use of such an organometallic catalyst facilitates excellent adhesion between the pressure-sensitive adhesive layer and the substrate, making it easier to prevent separation of the substrate and the pressure-sensitive adhesive layer during use.

[0041] Examples of the organotin compound include dibutyltin dilaurate (DBTDL), dioctyltin dilaurate (DOTDL), dibutyltin diacetate (DBTDA), dioctyltin diacetate (DOTDA), dioctyltin maleate (DOTM), dibutyltin maleate (DBTM), etc. Among these, it is preferable to use dibutyltin dilaurate (DBTDL).

[0042] When an organotin compound is used as the organometallic catalyst, the content of the organotin compound in the pressure-sensitive adhesive composition is preferably 0.001 parts by mass or more, particularly preferably 0.01 parts by mass or more, and even more preferably 0.02 parts by mass or more, relative to 100 parts by mass of the total amount of the monomers constituting the acrylic copolymer (a1). The content is also preferably less than 0.13 parts by mass, particularly preferably 0.1 parts by mass or less, and even more preferably 0.07 parts by mass or less.

[0043] The weight average molecular weight (Mw) of the active-energy radiation-curable polymer (A) thus obtained is preferably 100,000 or more, particularly preferably 200,000 or more, and even more preferably 300,000 or more. Furthermore, the weight average molecular weight (Mw) is preferably 1,200,000 or less, particularly preferably 1,000,000 or less, and even more preferably 800,000 or less. The weight average molecular weight (Mw) in this specification is a value measured by gel permeation chromatography (GPC) in terms of standard polystyrene.

[0044] (2-2) Acrylic polymer (B) having no active energy ray-curable group in the side chain As the acrylic polymer (B) having no active energy ray-curable group introduced into the side chain, for example, the same components as those of the above-mentioned acrylic copolymer (a1) can be used.

[0045] When the acrylic copolymer (a1) used as the acrylic polymer (B) contains the functional group-containing monomer, the mass ratio of the structural portion derived from the functional group-containing monomer in the acrylic copolymer (a1) is preferably 0.1% by mass or more, particularly preferably 1% by mass or more, and even more preferably 3% by mass or more. Furthermore, this ratio is preferably 30% by mass or less, particularly preferably 25% by mass or less, and even more preferably 20% by mass or less. By having the proportion of the structural portion derived from the functional group-containing monomer within the above range, the desired adhesive strength can be easily exhibited.

[0046] Furthermore, when the acrylic copolymer (a1) used as the acrylic polymer (B) contains the above-mentioned (meth)acrylic acid ester monomer, the mass proportion of the structural portion derived from the (meth)acrylic acid ester monomer in the acrylic copolymer (a1) is preferably 70 mass% or more, particularly preferably 75 mass% or more, and even more preferably 80 mass% or more. Furthermore, this proportion is preferably 99.9 mass% or less, particularly preferably 99 mass% or less, and even more preferably 97 mass% or less. By having the proportion of the structural portion derived from the (meth)acrylic acid ester monomer within the above range, the desired adhesive strength can be easily exhibited.

[0047] (2-3) Active energy ray-curable component The active energy ray-curable component in this embodiment is not particularly limited as long as it is a component having active energy ray-curability. In this specification, the active energy ray-curable component is different from the acrylic polymer (A) having an active energy ray-curable group introduced into its side chain.

[0048] When the pressure-sensitive adhesive composition of this embodiment contains an acrylic polymer (B) having no active energy ray-curable group introduced in its side chain, the pressure-sensitive adhesive composition may further contain an active energy ray-curable component, thereby causing the pressure-sensitive adhesive layer of this embodiment to exhibit good active energy ray-curability. Note that even when the pressure-sensitive adhesive composition of this embodiment contains an acrylic polymer (A) having an active energy ray-curable group introduced in its side chain, the pressure-sensitive adhesive composition may also contain an active energy ray-curable component.

[0049] Preferred examples of the active energy ray-curable component include active energy ray-curable monomers and / or oligomers. Specific examples include monofunctional acrylic acid esters such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate, polyfunctional acrylic acid esters such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and dimethyloltricyclodecane di(meth)acrylate, polyester oligo(meth)acrylate, polyurethane oligo(meth)acrylate, etc. These may be used alone or in combination of two or more.

[0050] When the pressure-sensitive adhesive composition of this embodiment contains an active energy ray-curable component together with an acrylic polymer (B) having no active energy ray-curable groups introduced into its side chains, the content of the active energy ray-curable component in the pressure-sensitive adhesive composition is preferably more than 30 parts by mass, and more preferably 60 parts by mass or more, per 100 parts by mass of the acrylic polymer (B). Furthermore, the content is preferably 250 parts by mass or less, and more preferably 200 parts by mass or less, per 100 parts by mass of the acrylic polymer (B).

[0051] (2-4) Ionic materials As described above, the ionic material in this embodiment is a non-halogen, non-metallic ion-based ionic material. By including such an ionic material in the adhesive composition in this embodiment, the adhesion of the workpiece processing sheet in this embodiment to the workpiece is appropriately suppressed, enabling excellent pickup properties to be achieved. Furthermore, since the ionic material is non-halogen-based, it can be fully utilized in applications requiring halogen-free properties. Furthermore, since the ionic material is non-metallic ion-based, it can be fully utilized in applications requiring metal-free properties. In particular, metal-free properties are highly required in devices for processing semiconductor wafers and devices equipped with semiconductor components, and this material can be fully utilized in these applications. In this specification, "non-halogen-based" refers to an ionic material composed of elements other than halogen elements. Furthermore, "non-metallic ion-based" refers to an ionic material composed of cations and anions other than metal ions.

[0052] The ionic material in this embodiment is not limited to its constituent cations and anions as long as it is non-halogen and non-metallic ion-based as described above. Furthermore, the ionic material in this embodiment may be either a liquid or a solid at room temperature.

[0053] Examples of cations constituting the ionic material in this embodiment include ammonium-based cations, imidazolium-based cations, phosphonium-based cations, pyridinium-based cations, pyrrolidinium-based cations, pyrrolinium-based cations, triazonium-based cations, etc. These may be used alone or in combination of two or more. Among these, ammonium-based cations and imidazolium-based cations are preferred.

[0054] Examples of the ammonium cation include a cation derived from an alkanolamine salt reaction product (alkanolamine cation), butyltrimethylammonium cation, ethyldiethylpropylammonium cation, 2-hydroxyethyl-triethylammonium cation, methyl-trioctylammonium cation, methyltrioctylammonium cation, tetrabutylammonium cation, tetraethylammonium cation, tetraheptylammonium cation, tributylmethylammonium cation, triethylmethylammonium cation, tris(2-hydroxy)methylammonium cation, ammonium cation, etc. These may be used alone or in combination of two or more.

[0055] Examples of the imidazolium cation include 1-allyl-3-methylimidazolium cation, 1-benzyl-3-methylimidazolium cation, 1,3-bis(cyanomethyl)imidazolium cation, 1,3-bis(cyanopropyl)imidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 4-(3-butyl)-1-imidazolium cation, 1-(3-cyanopropyl)-3-methylimidazolium cation, and the like. Examples include thione, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1,3-diethoxyimidazolium cation, 1,3-dimethoxy-2-methylimidazolium cation, 1-hexyl-3-methylimidazolium cation, 1-methyl-3-octylimidazolium cation, 1-methyl-3-propylimidazolium cation, etc. These may be used alone or in combination of two or more.

[0056] Examples of anions constituting the ionic material in this embodiment include sulfonate-based anions, carboxylate-based anions, carbonate-based anions, amide-based anions, phosphate-based anions, thiocyanate-based anions, nitrate-based anions, and borate-based anions. These may be used alone or in combination of two or more. Among these, sulfonate-based anions are preferred from the viewpoint of easily realizing excellent pick-up properties.

[0057] Examples of sulfonate anions include anions derived from the reaction product of glycol ether sulfate ester (glycol ether sulfate ester anion), anions derived from the reaction product of alkylbenzenesulfonic acid (alkylbenzenesulfonate anion), butylsulfonate anion, methylsulfonate anion, ethylsulfonate anion, hydrogensulfonate anion, octyl sulfonate anion, alkylsulfonate anion, etc. These may be used alone or in combination of two or more.

[0058] The content of the ionic material in the pressure-sensitive adhesive composition of this embodiment is preferably 0.01 parts by mass or more, particularly preferably 0.05 parts by mass or more, and even more preferably 0.1 parts by mass or more, per 100 parts by mass of the total amount of the acrylic polymer (A) and the acrylic polymer (B) (when only one of the acrylic polymer (A) and the acrylic polymer (B) is contained, the content of the contained component). Furthermore, the content of the ionic material is preferably 5 parts by mass or less, per 100 parts by mass of the total amount of the acrylic polymer (A) and the acrylic polymer (B). In particular, when the pressure-sensitive adhesive composition of this embodiment contains an acrylic polymer (A) having an active energy ray-curable group introduced into the side chain thereof and an ionic material, the content is preferably 3 parts by mass or less, and even more preferably 1 part by mass or less. Furthermore, when the pressure-sensitive adhesive composition of the present embodiment contains an acrylic polymer (B) having no active energy ray-curable groups introduced into its side chain, an active energy ray-curable component, and an ionic material, the content is particularly preferably 4 parts by mass or less, and more preferably 3 parts by mass or less. When the content of the ionic material is within the above range, the adhesiveness between the pressure-sensitive adhesive layer and the workpiece becomes appropriate, making it easier to achieve excellent pick-up properties.

[0059] (2-5) Crosslinking agent The pressure-sensitive adhesive composition in this embodiment preferably contains a crosslinking agent. By including a crosslinking agent in the pressure-sensitive adhesive composition, the acrylic polymer (A) or the acrylic polymer (B) crosslinks in the pressure-sensitive adhesive layer, forming a favorable three-dimensional network structure. This further improves the cohesive strength of the resulting pressure-sensitive adhesive, effectively suppressing the occurrence of adhesive residue on the workpiece separated from the workpiece processing sheet after irradiation with active energy rays. When the pressure-sensitive adhesive composition contains a crosslinking agent, the acrylic copolymer (a1) preferably contains the above-mentioned functional group-containing monomer as a monomer unit constituting the polymer, and in particular, preferably contains a functional group-containing monomer having a functional group highly reactive with the crosslinking agent used.

[0060] Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, amine-based crosslinking agents, melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, and ammonium salt-based crosslinking agents. These crosslinking agents can be selected depending on the functional groups derived from the functional group-containing monomers contained in the acrylic copolymer. These crosslinking agents can be used alone or in combination of two or more.

[0061] The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and biuret and isocyanurate forms thereof, as well as adducts thereof that are reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanates, particularly trimethylolpropane-modified tolylene diisocyanate, are preferred.

[0062] When the pressure-sensitive adhesive composition of this embodiment contains a crosslinking agent, the content of the crosslinking agent in the pressure-sensitive adhesive composition is preferably 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, and even more preferably 3 parts by mass or more, per 100 parts by mass of the total amount of the acrylic polymer (A) and the acrylic polymer (B) (when only one of the acrylic polymer (A) and the acrylic polymer (B) is contained, the content of the component contained). Furthermore, this content is preferably 20 parts by mass or less, particularly preferably 5 parts by mass or less. A crosslinking agent content of 0.1 parts by mass or more facilitates improving the cohesive strength of the pressure-sensitive adhesive layer after irradiation with active energy rays, thereby enabling effective suppression of adhesive residue. Furthermore, a crosslinking agent content of 20 parts by mass or less ensures an appropriate degree of crosslinking, making it easier for the pressure-sensitive adhesive layer to exhibit the desired adhesive strength.

[0063] (2-6) Photopolymerization initiator The pressure-sensitive adhesive composition in the present embodiment preferably contains a photopolymerization initiator. By containing the photopolymerization initiator in the pressure-sensitive adhesive composition, it is possible to reduce the polymerization curing time and the light irradiation dose when the pressure-sensitive adhesive layer is cured by irradiating it with active energy rays.

[0064] Examples of photopolymerization initiators include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane- Examples of photopolymerization initiators include 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one, ...

[0065] When the pressure-sensitive adhesive composition of this embodiment contains a photopolymerization initiator, the content of the photopolymerization initiator in the pressure-sensitive adhesive composition is preferably 0.1 parts by mass or more, and more preferably 1 part by mass or more, per 100 parts by mass of the total amount of the acrylic polymer (A) and the acrylic polymer (B) (when only one of the acrylic polymer (A) and the acrylic polymer (B) is contained, the content of the contained component). Furthermore, the content is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less. When the content of the photopolymerization initiator is within the above range, the pressure-sensitive adhesive layer can be efficiently cured by irradiation with active energy rays, which makes it easier to effectively reduce the adhesive strength of the workpiece processing sheet to the adherend.

[0066] (2-7) Other ingredients The adhesive composition of this embodiment can contain desired additives, such as silane coupling agents, antistatic agents, tackifiers, antioxidants, light stabilizers, softeners, fillers, refractive index adjusters, etc., as long as the effects of the workpiece processing sheet of this embodiment as described above are not impaired.

[0067] (2-8) Method for preparing pressure-sensitive adhesive composition The pressure-sensitive adhesive composition of this embodiment can be produced by producing an acrylic polymer (A) or an acrylic polymer (B), and mixing the resulting acrylic polymer (A) or acrylic polymer (B) with an ionic material, and optionally an active energy ray-curable component, a crosslinking agent, a photopolymerization initiator, and additives. At this time, a dilution solvent may be added, if desired, to obtain a coating liquid of the pressure-sensitive adhesive composition.

[0068] Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; and cellosolve-based solvents such as ethyl cellosolve.

[0069] The concentration and viscosity of the coating solution prepared in this manner are not particularly limited as long as they are within a range that allows coating, and can be appropriately selected depending on the situation. For example, the PSA composition is diluted so that its concentration is 10% by mass or more and 60% by mass or less. The addition of a dilution solvent or the like is not a necessary condition for obtaining the coating solution, and as long as the PSA composition has a viscosity that allows coating, it is not necessary to add a dilution solvent. In this case, the PSA composition becomes a coating solution in which the polymerization solvent for the acrylic copolymer (a1) is used as the dilution solvent.

[0070] (2-9) Thickness of adhesive layer In this embodiment, the thickness of the adhesive layer is preferably 1 μm or more, particularly preferably 3 μm or more, and even more preferably 5 μm or more. Having a thickness of 1 μm or more makes it easier for the workpiece processing sheet to exhibit good adhesive strength and to suppress chipping. Furthermore, the thickness is preferably 50 μm or less, particularly preferably 30 μm or less, and even more preferably 20 μm or less. Having a thickness of 50 μm or less makes it easier to pick up the workpiece.

[0071] (3) Release sheet In the workpiece processing sheet of this embodiment, a release sheet may be laminated on the side of the adhesive layer opposite the substrate (hereinafter sometimes referred to as the "adhesive side") in order to protect that side until it is attached to the workpiece.

[0072] The release sheet may have any configuration, and may be, for example, a plastic film that has been subjected to a release treatment using a release agent or the like. Specific examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. Examples of the release agent that can be used include silicone-based, fluorine-based, long-chain alkyl, and rubber-based agents, and among these, silicone-based agents are preferred because they are inexpensive and provide stable performance.

[0073] There are no particular limitations on the thickness of the release sheet, and it may be, for example, 16 μm or more and 250 μm or less.

[0074] (4) Other In the workpiece processing sheet according to this embodiment, an adhesive layer may be laminated on the surface of the adhesive layer opposite the substrate. In this case, the workpiece processing sheet according to this embodiment can be used as a dicing / die bonding sheet. In this sheet, a workpiece is attached to the surface of the adhesive layer opposite the adhesive layer, and the adhesive layer is diced together with the workpiece to obtain a chip on which the individualized adhesive layer is laminated. The individualized adhesive layer allows the chip to be easily fixed to the object on which it is to be mounted. As a material for constituting the adhesive layer, it is preferable to use a material containing a thermoplastic resin and a low-molecular-weight thermosetting adhesive component, or a material containing a B-stage (semi-cured) thermosetting adhesive component.

[0075] Furthermore, in the workpiece processing sheet according to this embodiment, a protective film forming layer may be laminated on the adhesive surface of the adhesive layer. In this case, the workpiece processing sheet according to this embodiment can be used as a sheet for both protective film formation and dicing. With such a sheet, a workpiece is attached to the surface of the protective film forming layer opposite the adhesive layer, and the protective film forming layer is diced together with the workpiece to obtain a chip on which a singulated protective film forming layer is laminated. It is preferable that the workpiece has a circuit formed on one side. In this case, the protective film forming layer is typically laminated on the surface opposite the surface on which the circuit is formed. By curing the singulated protective film forming layer at a predetermined timing, a protective film with sufficient durability can be formed on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

[0076] 2. Physical properties of workpiece processing sheets In the workpiece processing sheet according to this embodiment, the adhesive strength to a silicon wafer (the mirror surface of a mirror-finished silicon wafer, the same applies hereinafter) before irradiation with active energy rays is preferably 1000 mN / 25 mm or more, particularly preferably 1500 mN / 25 mm or more, and even more preferably 2000 mN / 25 mm or more. Having an adhesive strength to a silicon wafer of 1000 mN / 25 mm or more before irradiation with active energy rays makes it easier to secure the workpiece to the workpiece processing sheet, and effectively prevents unintended workpiece (especially workpieces after singulation) from falling off (especially chipping). While the upper limit of the adhesive strength is not particularly limited, it is preferably 20,000 mN / 25 mm or less, particularly preferably 10,000 mN / 25 mm or less, and even more preferably 7,000 mN / 25 mm or less. Details of the method for measuring the adhesive strength are as described in the test examples below.

[0077] Furthermore, in the workpiece processing sheet according to this embodiment, the adhesive strength to a silicon wafer after irradiation with active energy rays is preferably 90 mN / 25 mm or less, more preferably 80 mN / 25 mm or less, and even more preferably 70 mN / 25 mm or less. In the workpiece processing sheet according to this embodiment, the adhesive layer is composed of an active energy ray-curable adhesive formed from an adhesive composition containing a non-halogen, non-metallic ion-based ionic material, which makes it easier to achieve the above-mentioned adhesive strength after irradiation with active energy rays. Furthermore, an adhesive strength to a workpiece of 90 mN / 25 mm or less after irradiation with active energy rays makes it easier to peel the workpiece from the workpiece processing sheet. Furthermore, the adhesive strength to a silicon wafer after irradiation with active energy rays is preferably 10 mN / 25 mm or more, more preferably 15 mN / 25 mm or more, and even more preferably 20 mN / 25 mm or more. This makes it easier to prevent unintended separation or detachment of the workpiece after irradiation with active energy rays. Details of the method for measuring the adhesive strength are as described in the test examples below.

[0078] 3. Manufacturing method of workpiece processing sheet The method for producing the workpiece processing sheet according to this embodiment is not particularly limited, and it is preferably produced by laminating an adhesive layer on one side of a substrate.

[0079] The adhesive layer can be laminated on one side of the substrate by a known method. For example, it is preferable to transfer the adhesive layer formed on a release sheet to one side of the substrate. In this case, a coating liquid containing the adhesive composition constituting the adhesive layer and, optionally, a solvent or dispersion medium is prepared, and the coating liquid is applied to the release-treated surface of the release sheet (hereinafter sometimes referred to as the "release surface") using a die coater, curtain coater, spray coater, slit coater, knife coater, applicator, etc. to form a coating film, and the coating film is dried to form the adhesive layer. The properties of the coating liquid are not particularly limited as long as it can be applied, and it may contain the components for forming the adhesive layer as a solute or as a dispersoid. The release sheet in this laminate may be peeled off as a processing material, or it may be used to protect the adhesive surface of the adhesive layer until the work processing sheet is attached to the adherend.

[0080] When the coating solution for forming the adhesive layer contains a crosslinking agent, the crosslinking reaction between the acrylic copolymer in the coating film and the crosslinking agent can be promoted by changing the drying conditions (temperature, time, etc.) or by separately providing a heat treatment, thereby forming a crosslinked structure with the desired density in the adhesive layer. To promote this crosslinking reaction sufficiently, after laminating the adhesive layer on the substrate by the above-mentioned method, the resulting work processing sheet can be cured by, for example, leaving it in an environment of 23°C and a relative humidity of 50% for several days.

[0081] Instead of transferring the PSA layer formed on the release sheet to one side of the substrate as described above, the PSA layer may be formed directly on the substrate. In this case, the PSA layer is formed by applying the coating liquid for forming the PSA layer to one side of the substrate to form a coating film, and then drying the coating film.

[0082] 4. How to use the workpiece processing sheet The workpiece processing sheet according to this embodiment can be used to process workpieces such as semiconductor wafers. That is, after the adhesive surface of the workpiece processing sheet according to this embodiment is attached to the workpiece, the workpiece can be processed on the workpiece processing sheet. Depending on the processing, the workpiece processing sheet according to this embodiment can be used as a backgrinding sheet, dicing sheet, expanding sheet, pickup sheet, etc. Examples of workpieces include semiconductor components such as semiconductor wafers and semiconductor packages, and glass components such as glass plates.

[0083] As described above, the workpiece processing sheet according to this embodiment can effectively pick up chips obtained by dividing a workpiece, such as a semiconductor wafer. The chips may be obtained by dicing a separate sheet and then transferring them onto the workpiece processing sheet according to this embodiment, or they may be obtained by dicing on the workpiece processing sheet according to this embodiment. Therefore, the workpiece processing sheet according to this embodiment is particularly suitable for use as at least one of a dicing sheet and a pickup sheet.

[0084] When the workpiece processing sheet according to this embodiment has the adhesive layer described above, the workpiece processing sheet can be used as a dicing / die bonding sheet. Furthermore, when the workpiece processing sheet according to this embodiment has the protective film forming layer described above, the workpiece processing sheet can be used as a protective film forming / dicing sheet.

[0085] Furthermore, since the adhesive layer in the workpiece processing sheet according to this embodiment exhibits active energy ray curing properties, it is also preferable to irradiate the adhesive layer with active energy rays as follows during use. That is, it is preferable to irradiate the adhesive layer with active energy rays before separating the processed workpiece from the workpiece processing sheet. This hardens the adhesive layer, effectively reducing the adhesive strength of the adhesive sheet to the processed workpiece, and facilitating separation of the processed workpiece.

[0086] The above-described embodiments have been described to facilitate understanding of the present invention, and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention.

[0087] For example, another layer may be provided between the substrate and the pressure-sensitive adhesive layer, or on the surface of the substrate opposite to the pressure-sensitive adhesive layer. [Example]

[0088] The present invention will be explained in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0089] Example 1 (1) Preparation of the substrate Ethylene-methacrylic acid copolymer (EMAA) (manufactured by DuPont-Mitsui Polychemicals, product name: Nucrel N0903HC) was extruded using a small T-die extruder (manufactured by Toyo Seiki Seisakusho, product name: Labo Plastomill) to obtain an 80 μm-thick EMAA film. This EMAA film was used as the substrate.

[0090] (2) Preparation of adhesive composition 62 parts by mass of n-butyl acrylate, 10 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate were polymerized by solution polymerization to obtain an acrylic copolymer. The weight average molecular weight of the acrylic copolymer was measured by the method described below and was found to be 500,000.

[0091] Subsequently, methyl ethyl ketone was added to the obtained solution to adjust the solid content concentration. 35 % by mass. To this solution was added 2-methacryloyloxyethyl isocyanate (MOI) in an amount equivalent to 80 mol % of the 2-hydroxyethyl acrylate constituting the acrylic copolymer, and 0.200 parts by mass of dibutyltin dilaurate (DBTDL) as a tin-containing catalyst per 100 parts by mass of the total amount of the monomers was added. The mixture was then reacted at 50°C for 24 hours to obtain an acrylic polymer (A) having active energy ray-curable groups introduced into its side chains. The weight-average molecular weight of the acrylic polymer (A) was measured by the method described below and found to be 500,000.

[0092] 100 parts by mass of the obtained acrylic polymer (A) (solid content equivalent, the same applies below), 1.07 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate L") as a crosslinking agent, 2 parts by mass of 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one (manufactured by IGM Resins, product name "Omnirad 127") as a photopolymerization initiator, and 0.2 parts by mass of 1-ethyl-3-methylimidazolium p-toluenesulfonate (manufactured by Kanto Chemical Co., Ltd., molecular weight: 301) as an ionic material were mixed in a solvent to obtain a coating liquid of the adhesive composition (solid content concentration 28% by mass).

[0093] (3) Formation of adhesive layer The adhesive composition coating solution obtained in step (2) above was applied to the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET381031"), which was made of a 38 μm-thick polyethylene terephthalate film with a silicone-based release agent layer formed on one side thereof, and the resulting mixture was dried by heating to obtain a laminate in which a 5 μm-thick adhesive layer was formed on the release sheet.

[0094] (4) Preparation of adhesive sheet After corona treatment was applied to one side of the substrate obtained in the above step (1), the corona-treated side was bonded to the adhesive layer side of the laminate obtained in the above step (3) to obtain a work processing sheet.

[0095] (5) Measurement of weight-average molecular weight (Mw) of (meth)acrylic acid ester copolymer The weight average molecular weight (Mw) of the (meth)acrylic acid ester copolymer is a polystyrene-equivalent weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement). <Measurement conditions> GPC measuring device: Tosoh HLC-8320 GPC columns (passed in the following order): Tosoh Corporation TSK gel superH-H TSK gel super HM-H TSK gel superH2000 Measurement solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0096] Examples 2 to 6 A workpiece processing sheet was produced in the same manner as in Example 1, except that the type and content of the ionic material were changed as shown in Table 1.

[0097] Example 7 40 parts by mass of 2-ethylhexyl acrylate, 50 parts by mass of methacrylic acid, and 10 parts by mass of acrylic acid were polymerized by solution polymerization to obtain an acrylic copolymer (acrylic polymer (B) having no active energy ray-curable groups introduced into the side chains). The weight average molecular weight of the acrylic copolymer (B) was measured by the method described below and was found to be 800,000.

[0098] The resulting acrylic copolymer (B) contained 100 parts by mass, 40 parts by mass of a urethane acrylate oligomer (manufactured by Mitsubishi Chemical Corporation, product name "UV6630B") as an active energy ray-curable component, 40 parts by mass of tripentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Ltd., product name "Viscoat #802") as a polyfunctional acrylate monomer having 5 to 9 vinyl groups as an active energy ray-curable component, 11.4 parts by mass of trimethylolpropane-modified tolylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate L") as a crosslinking agent, 2 parts by mass of 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one (manufactured by IGM Resins, product name "Omnirad 127") as a photopolymerization initiator, and 1-ethyl-3-methylimidazolium as an ionic material. This was mixed with 3 parts by mass of p-toluenesulfonate (Kanto Chemical Co., Inc., molecular weight: 301) in a solvent to obtain a coating liquid of a pressure-sensitive adhesive composition (solid content concentration: 32% by mass).

[0099] A workpiece processing sheet was produced in the same manner as in Example 1, except that the obtained coating liquid of the adhesive composition was used.

[0100] Comparative Example 1 A workpiece processing sheet was produced in the same manner as in Example 1, except that no ionic material was used.

[0101] Details of the abbreviations and other information listed in Table 1 are as follows: [Acrylic polymer] BA: n-butyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate MOI: 2-methacryloyloxyethyl isocyanate 2EHA: 2-ethylhexyl acrylate MA: methacrylic acid AA: acrylic acid [Active energy ray-curable component] UV6630B: Urethane acrylate oligomer (manufactured by Mitsubishi Chemical Corporation, product name "UV6630B") Viscoat #802: A mixture of tripentaerythritol acrylate, mono- and dipentaerythritol acrylate, and polypentaerythritol acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., product name "Viscoat #802") [Ionic Materials] Aminoion AS100: Reaction product of alkanolamine and glycol sulfate (manufactured by Nippon Nyukazai Co., Ltd., product name "Aminoion AS100") Aminoion AS300: Reaction product of alkanolamine and alkylbenzenesulfonic acid (manufactured by Nippon Nyukazai Co., Ltd., product name "Aminoion AS300") Aminoion AS400: Reaction product of alkanolamine and dialkyl succinate sulfonic acid (manufactured by Nippon Nyukazai Co., Ltd., product name "Aminoion AS400")

[0102] [Test Example 1] (Measurement of adhesive strength) The workpiece processing sheets produced in the examples and comparative examples were cut into 25 mm wide strips. The release sheet was peeled off from the resulting strip-shaped workpiece processing sheets, and the exposed adhesive surface of the adhesive layer was attached to the mirror-finished surface of a silicon wafer using a 2 kg rubber roller at a temperature of 23 ° C. and a relative humidity of 50%, and then left to stand for 20 minutes to obtain a measurement sample. Note that the mirror surface of the silicon wafer was a surface (normal surface) that had been ground for more than one month and had lost activity.

[0103] Using a universal tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon UTM-4-100"), the workpiece processing sheet was peeled from the silicon wafer at a peeling speed of 300 mm / min and a peeling angle of 180°, and the adhesive strength (mN / 25 mm) to the silicon wafer was measured using the 180° peeling method in accordance with JIS Z0237: 2009. The adhesive strength obtained in this way was the adhesive strength before UV irradiation and is shown in Table 1.

[0104] In addition, the measurement samples obtained in the same manner as above were irradiated with ultraviolet (UV) light (illuminance: 230 mW / cm ) using an ultraviolet light irradiation device (manufactured by Lintec Corporation, product name "RAD-2000m / 12") in an environment of 23°C and 50% relative humidity 20 minutes after attachment to the silicon wafer. 2 , Light intensity: 190mJ / cm 2 ) was performed. After UV irradiation, the measurement sample was subjected to the same procedure as above, in which the workpiece processing sheet was separated from the silicon wafer, and the adhesive strength (mN / 25 mm) to the silicon wafer was measured. The adhesive strength thus obtained was taken as the adhesive strength after UV irradiation and is shown in Table 1.

[0105] [Test Example 2] (Pickup Evaluation) The release sheet was peeled off from the workpiece processing sheets produced in the Examples and Comparative Examples to expose the adhesive layer. Then, using a laminator, the exposed surface of the adhesive layer of the workpiece processing sheet was attached to the ground surface of a 6-inch silicon wafer (thickness 150 μm) whose one side had been ground in advance using a grinder (manufactured by Disco Corporation, product name "DFG8540").

[0106] Six hours after attachment, the silicon wafer was diced into individual chips on the workpiece processing sheet using a dicing device (manufactured by Disco Corporation, product name "DFD6362") under the following dicing conditions. Dicing Conditions Chip size: 10mm x 10mm Cutting height: 60 μm Blade: Product name "ZH05-SD2000-Z1-90 CC" Blade rotation speed: 35,000 rpm Cutting speed: 30mm / sec Cutting water amount: 1.0L / min Cutting water temperature: 20℃

[0107] Next, ultraviolet light (UV) was irradiated onto the substrate side of the workpiece processing sheet using an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2000m / 12") (illuminance: 230 mW / cm 2 ,Light amount: 190mJ / cm 2 ) to cure the adhesive layer.

[0108] Next, a single chip located near the center of the workpiece processing sheet was picked up using a pickup device at room temperature with a push-up speed of 5 mm / sec, a hold time of 0.1 msec, and a predetermined push-up amount set using a needle. Simultaneously with this push-up, a 10 mm x 10 mm vacuum collet was used to attempt to separate the chip from the workpiece processing sheet. These chip push-ups and collet separations were repeated while gradually changing the push-up amount. The minimum push-up amount (μm) was determined for three consecutive chips that could be picked up without any abnormalities. This minimum value is shown in Table 1 as the minimum push-up amount (μm).

[0109] [Table 1]

[0110] As can be seen from Table 1, the workpiece processing sheets obtained in the examples had a minimum push-up amount of 150 μm or less in the pickup evaluation, which indicated that excessive push-up was not required and that good pickup was possible. [Industrial Applicability]

[0111] The workpiece processing sheet of the present invention can be suitably used for processing workpieces such as semiconductor wafers.

Claims

1. A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, the pressure-sensitive adhesive layer is made of an active energy ray-curable pressure-sensitive adhesive formed from a pressure-sensitive adhesive composition containing a non-halogen and non-metal ion ionic material, The adhesive layer has a reduced adhesive strength to a workpiece when irradiated with active energy rays. A workpiece processing sheet characterized by:

2. 2. The workpiece processing sheet according to claim 1, wherein the anion constituting the ionic material is a sulfonate-based anion.

3. The pressure-sensitive adhesive composition contains, in addition to the ionic material, at least one of an acrylic polymer (A) having an active energy ray-curable group introduced into a side chain thereof and an acrylic polymer (B) having no active energy ray-curable group introduced into a side chain thereof, The content of the ionic material in the pressure-sensitive adhesive composition is 0.01 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the total amount of the acrylic polymer (A) and the acrylic polymer (B).

3. The workpiece processing sheet according to claim 1 or 2.

4. The work processing sheet according to any one of claims 1 to 3, characterized in that the adhesive composition contains an acrylic polymer (A) having an active energy ray-curable group introduced into a side chain and the ionic material.

5. The workpiece processing sheet according to any one of claims 1 to 3, characterized in that the adhesive composition contains an acrylic polymer (B) in which no active energy ray-curable group has been introduced into the side chain, an active energy ray-curable component, and the ionic material.

6. 6. The workpiece processing sheet according to claim 1, wherein the workpiece processing sheet is used as at least one of a dicing sheet and a pickup sheet.

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