Workpiece processing sheet and method for manufacturing processed workpiece

Abstract

To provide a sheet for processing a workpiece, which exhibits good adhesion to an active surface of the workpiece before irradiation with an active energy ray and enables good separation of the workpiece after the irradiation with the active energy ray, and a method for manufacturing a processed workpiece using the sheet for processing a workpiece.SOLUTION: A workpiece processing sheet comprising a base material and a pressure sensitive adhesive layer laminated on one side of the base material, wherein the pressure sensitive adhesive layer is composed of an active energy ray-curable pressure sensitive adhesive containing an alkylene glycol-modified rosin ester and a hindered amine-based stabilizer, and the workpiece processing sheet is to be attached to a ground surface of a workpiece within 120 minutes after the surface of the workpiece is ground.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a workpiece processing sheet suitable for use in processing workpieces such as semiconductor wafers, and a method for manufacturing a processed workpiece using the workpiece processing sheet. In particular, the present invention relates to a workpiece processing sheet suitable for use in processing workpieces having an active surface (hereinafter sometimes referred to as an "active surface"), and a method for manufacturing a processed workpiece using the workpiece processing sheet. [Background technology]

[0002] Semiconductor wafers such as silicon and gallium arsenide and various packages are manufactured in large diameters, cut (diced) into small element pieces (semiconductor chips), peeled (picked up), and then transferred to the next process, the mounting process. During this process, the semiconductor wafer or other workpiece is attached to a workpiece processing sheet that has a base material and an adhesive layer, and undergoes processing such as backgrinding, dicing, cleaning, drying, expanding, picking up, and mounting.

[0003] In the back-grinding process, the workpiece is typically fixed on a workpiece processing sheet, and the exposed surface of the workpiece is ground using a grinding device. After grinding, the workpiece is diced on the workpiece processing sheet in the dicing process and divided into multiple chips. The resulting multiple chips are then individually picked up from the workpiece processing sheet in the pick-up process.

[0004] The workpiece, one side of which has been ground in the back-grinding process, may be replaced with a new workpiece processing sheet prior to the grinding process. In this case, the adhesive layer side of the new workpiece processing sheet (hereinafter sometimes referred to as the "adhesive side") is attached to the ground surface, and the previous workpiece processing sheet is peeled off.

[0005] In recent years, the grinding, re-attaching, and dicing processes described above are sometimes performed continuously in-line. In this case, the workpiece processing sheet is attached to the ground surface of the workpiece immediately after grinding.

[0006] Generally, the grinding surface of a workpiece immediately after grinding is activated by grinding. Therefore, when attaching a workpiece processing sheet immediately after grinding the workpiece, the workpiece processing sheet is attached to the activated surface of the workpiece. In this case, due to the activation of the activated surface, the adhesion between the workpiece and the workpiece processing sheet tends to increase excessively. In particular, the adhesion tends to increase the longer the workpiece and the workpiece processing sheet are stacked. If the workpiece and the workpiece processing sheet are excessively adhered to each other in the subsequent pick-up process, the resulting chips will be strongly adhered to the workpiece processing sheet, making it impossible to pick up the chips properly.

[0007] Generally, in order to enable good pick-up, a workpiece processing sheet having an adhesive layer made of an adhesive having active energy ray curability is used. In this case, the adhesive layer is irradiated with active energy rays just before pick-up to harden the adhesive layer, thereby reducing the adhesive force to the chip and facilitating chip separation. However, even when using such a workpiece processing sheet, it is difficult to avoid the problem of poor pick-up as described above.

[0008] In order to solve the problems related to increased adhesion to the active surface of the workpiece as described above, Patent Document 1 discloses a workpiece processing sheet having an active energy ray-curable adhesive layer containing an alkylene glycol-modified rosin ester as a tackifier. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Patent No. 7254669 Summary of the Invention [Problem to be solved by the invention]

[0010] According to the workpiece processing sheet disclosed in Patent Document 1, when the sheet is attached to the activated surface of a workpiece, the adhesion to the workpiece after irradiation with active energy rays is reduced favorably, enabling good pickup. However, the inventors have confirmed that the adhesion of the workpiece processing sheet to the workpiece tends to decrease even before irradiation with active energy rays, which may result in unintended detachment or displacement of the workpiece.

[0011] The present invention has been made in consideration of the above-described circumstances, and aims to provide a workpiece processing sheet that exhibits good adhesion to the active surface of the workpiece before irradiation with active energy rays, while enabling good separation of the workpiece after irradiation with active energy rays, and a method for manufacturing processed workpieces using the workpiece processing sheet. [Means for solving the problem]

[0012] 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, wherein the adhesive layer is composed of an active energy ray-curable adhesive containing an alkylene glycol-modified rosin ester and a hindered amine-based stabilizer, and the workpiece processing sheet is intended to be attached to the ground surface of a workpiece within 120 minutes of grinding the surface of the workpiece (Invention 1).

[0013] In the workpiece processing sheet according to the above invention (Invention 1), the adhesive layer is composed of an active energy ray-curable adhesive containing an alkylene glycol-modified rosin ester and a hindered amine stabilizer, so that even when applied to the active surface of a workpiece, the sheet exhibits sufficient adhesion to the workpiece before exposure to active energy rays, and after exposure to active energy rays, the adhesive layer cures well, thereby effectively reducing adhesion to the workpiece. Therefore, the workpiece processing sheet prevents unintentional detachment or displacement of the workpiece, and allows easy separation of the workpiece, even after long-term storage after being applied to the active surface of the workpiece.

[0014] In the above invention (Invention 1), the hindered amine stabilizer is preferably an N-alkyl hindered amine stabilizer (Invention 2).

[0015] In the above inventions (Inventions 1 and 2), the molecular weight of the hindered amine stabilizer is preferably 500 or more (Invention 3).

[0016] In the above inventions (Inventions 1 to 3), the weight average molecular weight of the alkylene glycol-modified rosin ester is preferably 1,000 or more (Invention 4).

[0017] In the above inventions (Inventions 1 to 4), the active energy ray-curable adhesive is preferably formed from an adhesive composition containing an acrylic polymer having an active energy ray-curable group introduced into its side chain, the alkylene glycol-modified rosin ester, and the hindered amine-based stabilizer (Invention 5).

[0018] In the above invention (Invention 5), the pressure-sensitive adhesive composition preferably contains an antistatic agent (Invention 6).

[0019] Secondly, the present invention provides a method for manufacturing a processed workpiece, characterized by comprising a grinding step for grinding the surface of the workpiece, an attachment step for attaching the workpiece processing sheet (Inventions 1 to 6) to the ground surface of the workpiece, a dicing step for dicing the workpiece on the workpiece processing sheet to obtain a plurality of chips by dividing the workpiece, an active energy ray irradiation step for irradiating the adhesive layer on the workpiece processing sheet with active energy rays, and a pick-up step for individually picking up the chips from the workpiece processing sheet (Invention 7).

[0020] In the above invention (Invention 7), it is preferable that the attachment of the workpiece processing sheet to the workpiece in the attachment step is carried out within 120 minutes of grinding the surface of the workpiece in the grinding step (Invention 8). [Effects of the Invention]

[0021] The workpiece processing sheet according to the present invention exhibits good adhesion to the activated surface of the workpiece before irradiation with active energy rays, while enabling good separation of the workpiece after irradiation with active energy rays. Furthermore, the manufacturing method according to the present invention can produce good processed workpieces. DETAILED DESCRIPTION OF THE INVENTION

[0022] 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. The adhesive layer is composed of an active energy ray-curable adhesive containing an alkylene glycol-modified rosin ester and a hindered amine stabilizer. Furthermore, the workpiece processing sheet according to this embodiment is intended to be attached to the ground surface of a workpiece within 120 minutes of grinding the surface of the workpiece.

[0023] In the workpiece processing sheet according to this embodiment, the adhesive layer is made of an active energy ray-curable adhesive, so that the adhesive layer can be cured by irradiation with active energy rays, thereby reducing the adhesive strength to the workpiece. Therefore, when it is desired to separate the workpiece processing sheet according to this embodiment from the workpiece, the workpiece can be easily separated without damaging the workpiece or leaving part of the adhesive constituting the adhesive layer on the workpiece (glue residue).

[0024] In the workpiece processing sheet according to this embodiment, the active energy ray-curable adhesive contains an alkylene glycol-modified rosin ester and a hindered amine stabilizer, thereby enabling sufficient adhesion to the workpiece before exposure to active energy rays. Furthermore, even when the workpiece processing sheet is attached to the active surface of the workpiece and stored in that state for a long period of time, excessive adhesion to the workpiece is prevented. This allows the workpiece processing sheet to be easily separated from the workpiece by exposure to active energy rays, as described above.

[0025] In the workpiece processing sheet according to this embodiment, the reason why excessive increase in adhesion to the workpiece after irradiation with active energy rays is suppressed is expected to be, but is not limited to, the following.

[0026] First, the mechanism by which the workpiece surface is activated is thought to be that grinding the workpiece surface removes the inactive portions present on the surface and exposes the active portions inside. For example, if the workpiece is a silicon wafer, it is thought that under normal conditions, the surface of the silicon wafer is oxidized and an inactive SiO2 film is formed. When the surface of such a silicon wafer is ground, the SiO2 film is removed, exposing unoxidized silicon atoms. The exposed silicon atoms may react with the cleaning water used in the back-grinding process or with moisture in the air, partially forming Si-H or Si-OH structures. The exposed surface, after the SiO2 film has been removed, is prone to interacting with the adhesive surface of a typical workpiece processing sheet and to chemically bonding with the adhesive that makes up the adhesive layer.

[0027] Grinding the workpiece surface may also generate radicals, which may activate the surface. For example, on the ground surface, radicals (R·) are first generated by hydrogen abstraction from RH groups. Some of these radicals (R·) then react with oxygen molecules in the air to generate peroxy radicals (ROO·). Some of these radicals then abstract hydrogen from the RH groups, generating hydroperoxides (ROOH) and radicals (R·). Some of the generated hydroperoxides (ROOH) then decompose, generating oxyls (RO·) and hydroxyls (·OH). A surface with a large number of radicals generated in this way is prone to interacting with the adhesive surface of a typical workpiece processing sheet and to chemically bonding with the adhesive that makes up the adhesive layer.

[0028] Next, the mechanism by which the workpiece processing sheet according to this embodiment can suppress excessive increases in adhesion even to the activated surface of the workpiece generated as described above is thought to be as follows. The adhesive layer according to this embodiment is typically formed by forming a coating film using the above-described adhesive composition and curing the coating film. Here, the alkylene glycol-modified rosin ester contained in the adhesive composition has a relatively large molecular weight and relatively low compatibility with other components contained in the adhesive composition. Furthermore, the alkylene glycol-modified rosin ester has relatively high fluidity at room temperature and is easily mobile within the adhesive composition. Thus, the alkylene glycol-modified rosin ester's low compatibility with other components, combined with its easy mobility within the adhesive composition, results in the alkylene glycol-modified rosin ester being easily mobile to the surface of the coating film formed using the adhesive composition. By curing such a coating, an adhesive layer is formed in which the alkylene glycol-modified rosin ester is unevenly distributed near the surface, and as a result, the workpiece processing sheet according to this embodiment has the alkylene glycol-modified rosin ester unevenly distributed near its adhesive surface. The alkylene glycol-modified rosin ester present near the adhesive surface is thought to act to suppress the aforementioned interaction and chemical bonding with the active surface of the workpiece, thereby suppressing excessive adhesion between the active surface of the workpiece and the workpiece processing sheet according to this embodiment.

[0029] Furthermore, in the workpiece processing sheet according to this embodiment, the hindered amine stabilizer and the stable radicals generated in the system as a result thereof are thought to trap or inactivate the generated radicals as described above, thereby suppressing interactions with the active energy ray-curable adhesive and the formation of chemical bonds. As a result, the workpiece processing sheet according to this embodiment can effectively suppress an increase in adhesion to the active surface.

[0030] In particular, hindered amine stabilizers are believed to be able to trap at least three of the above-mentioned multiple radicals: R·, RO·, and ROO·. In contrast, other stabilizers (hindered phenol stabilizers, phosphite stabilizers, etc.) can trap fewer types of radicals or cannot trap radicals at all. Therefore, the workpiece processing sheet according to this embodiment uses a hindered amine stabilizer, making it possible to effectively suppress an increase in adhesion to the active surface.

[0031] Furthermore, after trapping the radical (bonding with the radical), the hindered amine stabilizer undergoes a reaction that re-cleaves the radical moiety, resulting in the hindered amine stabilizer being regenerated. Therefore, the hindered amine stabilizer can continuously exert its stabilizer effect. This regeneration action does not occur with the hindered phenol compounds that have been used conventionally. For this reason, the workpiece processing sheet according to this embodiment can effectively suppress an increase in adhesion to the active surface.

[0032] The combined effects of the alkylene glycol-modified rosin ester and the hindered amine stabilizer described above allow the workpiece processing sheet according to this embodiment to suppress excessive adhesion to the workpiece, making it easy to separate the workpiece by irradiating it with active energy rays. Furthermore, by using the alkylene glycol-modified rosin ester and the hindered amine stabilizer in combination, the workpiece processing sheet according to this embodiment can suppress the problem of excessively reduced adhesion to the workpiece before irradiating it with active energy rays, which occurs when using the alkylene glycol-modified rosin ester alone. As a result, the workpiece processing sheet according to this embodiment allows for good workpiece processing.

[0033] In this specification, the surface of the workpiece being in an activated state refers to a state within 120 minutes after the surface of the workpiece has been ground, preferably within 30 minutes after the surface of the workpiece has been ground, and more preferably within 5 minutes after the surface of the workpiece has been ground.

[0034] Furthermore, after the workpiece processing sheet according to this embodiment is attached to the active surface of the workpiece, the storage period of the laminate of the workpiece and the workpiece processing sheet can be set according to the purpose of use. Generally, the storage period is often 0 to 500 days, particularly 1 to 90 days, and more often 7 to 30 days.

[0035] 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 in this embodiment is preferably composed of a resin. Examples of such resins include polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polyolefin-based resins such as polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymer, and norbornene resin; ethylene-vinyl acetate copolymer; ethylene-based copolymer resins such as ethylene-(meth)acrylic acid copolymer, ethylene-methyl(meth)acrylate copolymer, and other ethylene-(meth)acrylic acid ester copolymers; polyvinyl chloride-based resins such as polyvinyl chloride and vinyl chloride copolymers; (meth)acrylic acid ester copolymers; polyurethane; polyimide; polystyrene; polycarbonate; and fluororesins. The resin constituting the substrate may also be a crosslinked version of the above-mentioned resin or a modified version of the above-mentioned resin, such as an ionomer. Note that, in this specification, "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid. The same applies to other similar terms. In addition, the term "polymer" in this specification also includes the concept of "copolymer."

[0036] The substrate in this embodiment may be a single-layer film made of the above-mentioned resin, or may be a laminate film made of a plurality of such films. In this laminate film, the materials constituting the layers may be the same or different.

[0037] 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.

[0038] The substrate is preferably transparent to active energy rays. By using such a substrate, the pressure-sensitive adhesive layer can be easily cured well even when the pressure-sensitive adhesive layer is irradiated with active energy rays through the substrate.

[0039] Furthermore, 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.

[0040] 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.

[0041] 2. Adhesive layer As described above, the adhesive layer in this embodiment is composed of an active energy ray-curable adhesive containing an alkylene glycol-modified rosin ester and a hindered amine-based stabilizer.

[0042] Examples of the pressure-sensitive adhesive are not particularly limited, and include acrylic pressure-sensitive adhesives, rubber pressure-sensitive adhesives, silicone pressure-sensitive adhesives, urethane pressure-sensitive adhesives, polyester pressure-sensitive adhesives, polyvinyl ether pressure-sensitive adhesives, etc. However, from the viewpoints of ease of forming an active energy ray-curable pressure-sensitive adhesive and ease of exerting the desired adhesive strength, it is preferable to use an acrylic pressure-sensitive adhesive.

[0043] The active energy ray-curable adhesive may be one primarily composed of an active energy ray-curable polymer, or one primarily composed of a mixture of a non-active energy ray-curable polymer (a polymer not curable with active energy rays) and a monomer and / or oligomer having at least one active energy ray-curable group. Furthermore, the active energy ray-curable adhesive may be a mixture of an active energy ray-curable polymer and a monomer and / or oligomer having at least one active energy ray-curable group. Among these, the active energy ray-curable adhesive of this embodiment is preferably one primarily composed of an active energy ray-curable polymer (particularly, an active energy ray-curable acrylic polymer), from the viewpoints of suppressing adverse effects due to excessive increase in adhesive strength even after heat treatment and facilitating good workpiece separation by reducing adhesive strength using a trigger.

[0044] The active energy ray-curable acrylic polymer is preferably an acrylic polymer having an active energy ray-curable functional group (active energy ray-curable group) introduced into its side chain (hereinafter, this may be referred to as "active energy ray-curable polymer (A)"). In this case, the active energy ray-curable pressure-sensitive adhesive of the present embodiment is preferably formed from a pressure-sensitive adhesive composition containing an acrylic polymer having an active energy ray-curable group introduced into its side chain (active energy ray-curable polymer (A)), an alkylene glycol-modified rosin ester, and a hindered amine-based stabilizer.

[0045] (1) Active energy radiation curable polymer (A) The active energy radiation-curable polymer (A) is preferably obtained by reacting a (meth)acrylic acid ester polymer (a1) having a functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group of the (meth)acrylic acid ester polymer (a1).

[0046] As the functional group-containing monomer described above, a monomer having a polymerizable double bond and a functional group such as a hydroxy group, a carboxyl group, an amino group, an amide group, a benzyl group, or a glycidyl group in the molecule is preferred, and among these, it is preferred to use a monomer containing a hydroxy group as the functional group (a hydroxy group-containing monomer).

[0047] Examples of the hydroxy group-containing monomer 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, and among these, it is preferable to use at least one of 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate. These may be used alone or in combination of two or more.

[0048] Examples of the carboxyl 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.

[0049] Examples of the amino group-containing monomer or amide group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0050] The (meth)acrylic acid ester polymer (a1) preferably contains 5% by mass or more, and more preferably 10% by mass or more, of structural units derived from the functional group-containing monomer. The (meth)acrylic acid ester polymer (a1) preferably contains 40% by mass or less, and more preferably 35% by mass or less, of structural units derived from the functional group-containing monomer. The (meth)acrylic acid ester polymer (a1) containing the functional group-containing monomer in the above range facilitates the formation of the desired active-energy radiation-curable polymer (A).

[0051] From the viewpoint of facilitating the formation of a pressure-sensitive adhesive having the desired properties, the (meth)acrylic acid ester polymer (a1) preferably contains a (meth)acrylic acid alkyl ester as a monomer unit constituting the (meth)acrylic acid ester polymer (a1). The (meth)acrylic acid alkyl ester preferably has an alkyl group having 1 to 18 carbon atoms, and more preferably has an alkyl group having 1 to 8 carbon atoms.

[0052] Specific examples of the (meth)acrylic acid alkyl ester include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. These may be used alone or in combination of two or more. Among the above-mentioned (meth)acrylic acid alkyl esters, it is preferable to use at least one of n-butyl (meth)acrylate and 2-ethylhexyl acrylate.

[0053] The (meth)acrylic acid ester polymer (a1) preferably contains 20% by mass or more, and more preferably 30% by mass or more, of the structural units derived from the (meth)acrylic acid alkyl ester. The (meth)acrylic acid ester polymer (a1) preferably contains 95% by mass or less, and more preferably 85% by mass or less, of the structural units derived from the (meth)acrylic acid alkyl ester. By including the (meth)acrylic acid alkyl ester in the above range in the (meth)acrylic acid ester polymer (a1), the workpiece processing sheet can easily exhibit the desired adhesive strength.

[0054] The (meth)acrylic acid ester polymer (a1) may contain, as monomer units constituting the (meth)acrylic acid ester polymer (a1), other monomers in addition to the functional group-containing monomer and the (meth)acrylic acid alkyl ester described above.

[0055] Examples of the other monomers include nitrogen atom-containing monomers; alkoxyalkyl group-containing (meth)acrylic acid esters such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate; (meth)acrylic acid esters having an aliphatic ring such as cyclohexyl (meth)acrylate; (meth)acrylic acid esters having an aromatic ring such as phenyl (meth)acrylate; non-crosslinkable acrylamides such as (meth)acrylamide and N,N-dimethyl(meth)acrylamide; non-crosslinkable (meth)acrylic acid esters having a tertiary amino group such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; vinyl acetate; and styrene.

[0056] Examples of the nitrogen atom-containing monomer include a monomer having an amino group, a monomer having an amide group, a monomer having a nitrogen-containing heterocycle, etc. Furthermore, examples of the monomer having a nitrogen-containing heterocycle include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinylphthalimide.

[0057] It is also preferable that the (meth)acrylic acid ester polymer (a1) uses, as a monomer unit constituting the (meth)acrylic acid ester polymer (a1), a monomer having a glass transition temperature (Tg) of more than 10°C as a homopolymer. Examples of such a monomer include vinyl acetate, N-(meth)acryloylmorpholine, and methyl methacrylate. When using such a monomer, the (meth)acrylic acid ester polymer (a1) preferably contains 10% by mass or more and 60% by mass or less of the structural unit derived from the monomer.

[0058] The (meth)acrylic acid ester polymer (a1) may be a random copolymer or a block copolymer, and the polymerization method is not particularly limited, and it can be polymerized by a general polymerization method, such as solution polymerization.

[0059] The (meth)acrylic acid ester polymer (a1) having the functional group-containing monomer unit is reacted with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group, thereby obtaining an active energy radiation-curable polymer (A).

[0060] 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 (meth)acrylic acid ester polymer (a1). For example, when the functional group of the (meth)acrylic acid ester polymer (a1) is a hydroxy group, an amino group, or a carboxyl group, the functional group of the unsaturated group-containing compound (a2) is preferably an isocyanate group, an epoxy group, or an aziridinyl group, and when the functional group of the (meth)acrylic acid ester polymer (a1) is a glycidyl group, the functional group of the unsaturated group-containing compound (a2) is preferably an amino group, a carboxyl group, or an aziridinyl group.

[0061] 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 bond per molecule. Specific examples of such unsaturated group-containing compound (a2) include 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-(2-methacryloyloxyethyloxy)ethyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; diisocyanate compounds. Alternatively, examples include an acryloyl monoisocyanate compound obtained by reacting a polyisocyanate compound with hydroxyethyl (meth)acrylate; an acryloyl monoisocyanate compound 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, and 2-isopropenyl-2-oxazoline.

[0062] The unsaturated group-containing compound (a2) is used in an amount of preferably 50 mol % or more, particularly preferably 60 mol % or more, and even more preferably 70 mol % or more, based on the moles of the functional group-containing monomer in the (meth)acrylic acid ester polymer (a1). The unsaturated group-containing compound (a2) is used in an amount of preferably 95 mol % or less, particularly preferably 93 mol % or less, and even more preferably 90 mol % or less, based on the moles of the functional group-containing monomer in the (meth)acrylic acid ester polymer (a1).

[0063] In the reaction of the (meth)acrylic acid ester polymer (a1) with 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 (meth)acrylic acid ester polymer (a1) and the unsaturated group-containing compound (a2). As a result, the functional groups present in the (meth)acrylic acid ester polymer (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 (meth)acrylic acid ester polymer (a1), thereby obtaining an active-energy radiation-curable polymer (A).

[0064] The weight average molecular weight (Mw) of the active-energy radiation-curable polymer (A) thus obtained is preferably 10,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more. Furthermore, the weight average molecular weight (Mw) is preferably 1,500,000 or less, particularly preferably 1,000,000 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.

[0065] (2) Alkylene glycol modified rosin ester Although there are no particular limitations on the alkylene glycol-modified rosin ester, it is preferable that the alkylene glycol-modified rosin ester be one obtained by subjecting a rosin, a polyalkylene glycol monoalkyl ether, a polyhydric alcohol, and an α,β-unsaturated carboxylic acid to an esterification reaction.

[0066] The alkylene glycol-modified rosin ester preferably has a softening point of 50°C or lower, particularly 20°C or lower, and even more preferably 0°C or lower. A softening point of 50°C or lower increases the fluidity of the alkylene glycol-modified rosin ester, making it easier to prevent excessive adhesion of the workpiece processing sheet according to this embodiment to the active surface of the workpiece. The lower limit of the softening point is not particularly limited, but is preferably -100°C or higher, particularly -70°C or higher, and even more preferably -40°C or higher.

[0067] The alkylene glycol-modified rosin ester preferably has a weight-average molecular weight of 1,000 or more, more preferably 2,000 or more, and even more preferably 3,000 or more. A weight-average molecular weight of 1,000 or more facilitates a moderate decrease in the compatibility of the alkylene glycol-modified rosin ester with other components in the adhesive composition, thereby making it easier to prevent excessive increases in adhesion of the workpiece processing sheet according to this embodiment to the active surface of the workpiece. From the viewpoint of compatibility with the adhesive composition, the upper limit of the weight-average molecular weight is preferably 1,000,000 or less, more preferably 100,000 or less, particularly preferably 50,000 or less, and even more preferably 8,000 or less.

[0068] The content of alkylene glycol-modified rosin ester in the adhesive composition is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, relative to 100 parts by mass of the acrylic polymer having an active energy ray-curable group introduced into its side chain (active energy ray-curable polymer (A)). A content of 0.01 parts by mass or more facilitates effective suppression of the above-mentioned excessive increase in adhesion. Furthermore, the content is preferably 25 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 4 parts by mass or less, relative to 100 parts by mass of the acrylic polymer having an active energy ray-curable group introduced into its side chain (active energy ray-curable polymer (A)). A content of 25 parts by mass or less facilitates the workpiece processing sheet according to this embodiment to have the adhesive strength required for processing the workpiece.

[0069] (3) Hindered amine stabilizers In this specification, the hindered amine stabilizer refers to a stabilizer having one or more amine skeletons in the molecule. The hindered amine stabilizer in this embodiment is not particularly limited as long as it has such a structure.

[0070] Generally, hindered amine stabilizers include N-alkyl hindered amine stabilizers, which are compounds having one or more structures in which an alkyl group is bonded to a nitrogen atom of a 2,2,6,6-tetramethylpiperidine skeleton in the molecule; N-alkoxy hindered amine stabilizers, which are compounds having one or more structures in which an alkoxy group is bonded to a nitrogen atom of a 2,2,6,6-tetramethylpiperidine skeleton in the molecule; and NH-type hindered amine stabilizers, which are compounds having one or more structures in which a hydrogen atom is bonded to a nitrogen atom of a 2,2,6,6-tetramethylpiperidine skeleton in the molecule. While any of these compounds can be used to obtain good results in the workpiece processing sheet according to this embodiment, it is preferable to use an N-alkyl hindered amine stabilizer, as this stabilizer facilitates easy separation of the workpiece even after long-term storage while attached to the active surface of the workpiece.

[0071] Examples of the alkyl group in the N-alkyl hindered amine stabilizer include methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, and n-octyl groups. Among these, the methyl group is preferred from the viewpoint of achieving easy separation of the workpiece even after long-term storage while attached to the active surface of the workpiece.

[0072] Specific examples of hindered amine stabilizers include p,p'-dioctyldiphenylamine, phenyl-α-naphthylamine, poly(2,2,4-trimethyl-1,2-dihydroquinoline), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N,N'-diphenyl-p-phenylenediamine, N,N'-di-β-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N,N'-diallyl-p-phenylenediamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, and p,p-toluenesulfonyl ether. phenylsulfonylaminodiphenylamine, N-phenyl-N'-(3-methacloryloxy-2-hydroxypropyl)-p-phenylenediamine, N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine, N,N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N'-1,3-dimethylbutyl-p-phenylenediamine, alkylated diphenylamines, dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, poly[[6-(1,1,3,3-tetramethylpiperidine N,N'-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)imino, N,N'-bis(3-aminopropyl)ethylenediamine-2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidyl)amino]-6-chloro-1,3,5-triazine condensate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-n-butylmalonate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, tetrakis(2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, 1,2,3,4-butanetetracarboxylic acid and 1,2,Mixed esters of 2,6,6-pentamethyl-4-piperidinol and 1-tridecanol, mixed esters of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 1-tridecanol, mixed esters of 1,2,3,4-butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane mixed esters of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, (2,2,6,6-tetramethylene-4-piperidyl)-2-propylenecarboxylate, and (1,2,2,6,6-pentamethyl-4-piperidyl)-2-propylenecarboxylate.

[0073] Among the above specific examples, it is preferable to use a mixed ester of 1,2,3,4-butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane as an N-alkyl hindered amine stabilizer.

[0074] Furthermore, it is preferable to use a hindered amine stabilizer having a molecular weight of 500 or more, particularly 1000 or more, and even more preferably 2000 or more. Having a molecular weight of 500 or more makes it easier for the compatibility of the hindered amine stabilizer with other components in the adhesive composition to decrease moderately, and as a result, the workpiece processing sheet according to this embodiment is more likely to suppress excessive increases in adhesion to the active surface of the workpiece. From the viewpoint of compatibility with the adhesive composition, the upper limit of the molecular weight is preferably 1 million or less, more preferably 100,000 or less, particularly preferably 50,000 or less, and even more preferably 8000 or less.

[0075] The molar mass of the hindered amine stabilizer is preferably 200 g / mol or more, particularly preferably 600 g / mol or more, and even more preferably 1000 g / mol or more. The molar mass is preferably 10000 g / mol or less, particularly preferably 5000 g / mol or less, and even more preferably 3000 g / mol or less. When the molar mass of the hindered amine stabilizer is within this range, it becomes easier to achieve easy separation of the workpiece, even after long-term storage while attached to the active surface of the workpiece.

[0076] The content of the hindered amine stabilizer 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 1.0 parts by mass or more, relative to 100 parts by mass of the acrylic polymer having an active energy ray-curable group introduced into the side chain (active energy ray-curable polymer (A)). Furthermore, the content is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and even more preferably 15 parts by mass or less. By having the content of the hindered amine stabilizer within this range, it becomes easier to achieve easy separation of the workpiece, even after long-term storage while attached to the active surface of the workpiece.

[0077] (4) Crosslinking agent The above-mentioned adhesive composition also preferably contains a crosslinking agent. By including a crosslinking agent in the adhesive composition, the active energy radiation-curable polymer (A) crosslinks in the adhesive layer, enabling the formation of a good three-dimensional network structure. This further improves the cohesive strength of the resulting 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 adhesive composition contains a crosslinking agent, the active energy radiation-curable polymer (A) 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.

[0078] 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.

[0079] The isocyanate crosslinking agent contains at least a polyisocyanate compound, such as 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, it is preferable to use at least one of an isocyanurate of hexamethylene diisocyanate, particularly an isocyanurate trimer of 1,6-hexamethylene diisocyanate, trimethylolpropane-modified tolylene diisocyanate, and trimethylolpropane-modified hexamethylene diisocyanate.

[0080] When the pressure-sensitive adhesive composition described above contains a crosslinking agent, the content of the crosslinking agent in the pressure-sensitive adhesive composition is preferably 0.01 parts by mass or more, particularly preferably 0.1 parts by mass or more, and even more preferably 0.4 parts by mass or more, relative to 100 parts by mass of the active energy radiation-curable polymer (A). Furthermore, this content is preferably 20 parts by mass or less, particularly preferably 5 parts by mass or less. A crosslinking agent content of 0.01 parts by mass or more facilitates improving the cohesive strength of the pressure-sensitive adhesive layer after irradiation with active energy rays, thereby making it possible to effectively suppress 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.

[0081] (5) Photopolymerization initiator The pressure-sensitive adhesive composition of the present embodiment also preferably contains a photopolymerization initiator. By containing the photopolymerization initiator in the pressure-sensitive adhesive composition, the polymerization curing time and the light irradiation dose when the pressure-sensitive adhesive layer is cured by irradiating with active energy rays can be reduced.

[0082] 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, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diazobisisobutyronitrile, benzoin methyl ether ...methyl ether, benzoin methyl ether, benzoin methyl ether, benzoin methyl ether, benzoin methyl ether, benzoin methyl ether, benzoin methyl ether, benzoin methyl ether, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diazobisisobutyronitrile, benzoin methyl ether, benzoin methyl ether, benzoin methyl Examples of suitable photopolymerization initiators include cetyl, β-chloroanthraquinone, (2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one), (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, and 2,2-dimethoxy-1,2-diphenylethan-1-one. Among these, it is preferable to use at least one of 1-hydroxycyclohexyl phenyl ketone and (2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propan-1-one). The photopolymerization initiators described above may be used alone or in combination of two or more.

[0083] When the pressure-sensitive adhesive composition 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, particularly preferably 1 part by mass or more, relative to 100 parts by mass of the active energy ray-curable polymer (A). Furthermore, the content is preferably 20 parts by mass or less, particularly 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.

[0084] (6) Other ingredients The adhesive composition described above can contain desired additives, such as silane coupling agents, antistatic agents, tackifiers, antioxidants, softeners, fillers, refractive index adjusters, etc., as long as the effects of the workpiece processing sheet according to this embodiment are not impaired.

[0085] Among the above additives, it is particularly preferable to use an antistatic agent. Workpiece processing sheets generally become charged during transportation or use, and this charging can cause damage to semiconductor chips and malfunctions of dicing machines. For example, when separating a processed workpiece from a workpiece processing sheet, static electricity known as peel charging can occur between the workpiece processing sheet and the processed workpiece. If the processed workpiece is, for example, a semiconductor chip, this generation of static electricity can cause damage to the circuits formed on the chip. The use of an antistatic agent in the workpiece processing sheet according to this embodiment makes it easier to suppress the above-mentioned charging, facilitating good workpiece processing.

[0086] The antistatic agent is not particularly limited, and examples thereof include conductive polymers, conductive fillers, anionic or cationic compounds, and compounds having a quaternary ammonium base in the main chain or side chain of the molecule.

[0087] Examples of anionic and cationic compounds include ionic liquids, ionic solids, anionic surfactants, alkali metal salts, cationic surfactants, and nonionic surfactants. Examples of ionic liquids and ionic solids include nitrogen-containing onium salts, sulfur-containing onium salts, phosphorus-containing onium salts, and boron-containing onium salts. Examples of alkali metal salts include lithium salts and potassium salts. These may be used alone or in combination of two or more.

[0088] When the pressure-sensitive adhesive composition described above contains an antistatic agent, the content of the antistatic agent in the pressure-sensitive adhesive composition is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, relative to 100 parts by mass of the active-energy radiation-curable polymer (A). Furthermore, the content is preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less. By ensuring that the content of the antistatic agent is within the above range, the above-mentioned charging can be effectively suppressed.

[0089] (7) Method for preparing pressure-sensitive adhesive composition The pressure-sensitive adhesive composition in this embodiment can be produced by producing an active-energy radiation-curable polymer (A), and mixing the obtained active-energy radiation-curable polymer (A), an alkylene glycol-modified rosin ester, a hindered amine-based stabilizer, and optionally a crosslinking agent, a photopolymerization initiator, and desired additives. At this time, a dilution solvent may be added, if desired, to obtain a coating liquid of the pressure-sensitive adhesive composition.

[0090] 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.

[0091] 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.

[0092] (8) 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 4 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 75 μm or less, particularly preferably 30 μm or less, and even more preferably 20 μm or less. Having a thickness of 75 μm or less makes it easier to separate the workpiece.

[0093] 3. Other configurations In the workpiece processing sheet according to this embodiment, a release sheet may be laminated on the side of the adhesive layer opposite the substrate (adhesive side) to protect that side until it is attached to the workpiece.

[0094] 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.

[0095] 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.

[0096] Furthermore, 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 an 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.

[0097] 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.

[0098] 4. Physical properties of workpiece processing sheets (1) Adhesion strength before irradiation with active energy rays In the workpiece processing sheet according to this embodiment, the adhesive strength of the workpiece processing sheet to the mirror surface of a silicon wafer before irradiation with active energy rays is preferably 1000 mN / 25 mm or more, more preferably 2000 mN / 25 mm or more, and even more preferably 3000 mN / 25 mm or more. As described above, the adhesive layer of the workpiece processing sheet according to this embodiment is formed using an adhesive composition containing an alkylene glycol-modified rosin ester and a hindered amine stabilizer, thereby achieving the above-mentioned adhesive strength before irradiation with active energy rays. Having an adhesive strength of 1000 mN / 25 mm or more facilitates the satisfactory fixation of the workpiece to the adhesive surface of the workpiece processing sheet. As a result, the workpiece can be processed more efficiently, effectively suppressing chipping and chipping during dicing, for example. Furthermore, the adhesive strength is preferably 20,000 mN / 25 mm or less, particularly preferably 17,000 mN / 25 mm or less, and even more preferably 15,000 mN / 25 mm or less. Having the adhesive strength of 20,000 mN / 25 mm or less makes it easier to suppress excessive increases in adhesion to the activated surface of the workpiece. Note that the mirror surface of the silicon wafer is not the activated surface. Details of the method for measuring the adhesive strength are as described in the test examples below.

[0099] (2) Adhesion strength to the active surface before irradiation with active energy rays In the workpiece processing sheet according to this embodiment, the adhesive surface of the workpiece processing sheet is applied to the ground surface 5 minutes after grinding the surface of a silicon wafer. After 20 minutes, the adhesive strength of the workpiece processing sheet to the ground surface before irradiation with active energy rays is preferably 3000 mN / 25 mm or more, more preferably 5000 mN / 25 mm or more, and even more preferably 7000 mN / 25 mm or more. As described above, the workpiece processing sheet according to this embodiment has an adhesive layer formed using an adhesive composition containing an alkylene glycol-modified rosin ester and a hindered amine stabilizer, thereby achieving the above-mentioned adhesive strength before irradiation with active energy rays. Having an adhesive strength of 3000 mN / 25 mm or more facilitates the satisfactory fixation of the workpiece to the adhesive surface of the workpiece processing sheet. As a result, workpiece processing can be performed more efficiently, effectively suppressing chipping and chip flyoff during dicing, for example. Furthermore, the adhesive strength is preferably 20,000 mN / 25 mm or less, particularly preferably 17,000 mN / 25 mm or less, and even more preferably 15,000 mN / 25 mm or less. By ensuring that the adhesive strength is 20,000 mN / 25 mm or less, it becomes easier to suppress an excessive increase in adhesion to the activated surface of the workpiece. Details of the method for measuring the adhesive strength are as described in the test examples below.

[0100] (3) Adhesion strength after irradiation of active energy rays to the activated surface In the workpiece processing sheet according to this embodiment, the adhesive surface of the workpiece processing sheet is applied to the ground surface within 5 minutes of grinding the surface of a silicon wafer. After 7 days, the workpiece processing sheet is irradiated with active energy rays. The adhesive strength of the workpiece processing sheet to the ground surface is preferably 400 mN / 25 mm or less, more preferably 300 mN / 25 mm or less, particularly preferably 200 mN / 25 mm or less, and even more preferably 150 mN / 25 mm or less. Having an adhesive strength of 150 mN / 25 mm or less facilitates the separation of the processed workpiece from the workpiece processing sheet, even when the workpiece has an active surface. As described above, the workpiece processing sheet according to this embodiment has an adhesive layer formed from an adhesive composition containing an alkylene glycol-modified rosin ester and a hindered amine stabilizer, thereby achieving the above-described adhesive strength even to the active surface of the workpiece. Furthermore, the adhesive strength is preferably 10 mN / 25 mm or more, particularly preferably 50 mN / 25 mm or more, and even more preferably 70 mN / 25 mm or more. By having the adhesive strength of 10 mN / 25 mm or less, it becomes easier to effectively prevent the processed workpiece from unintentionally detaching from the workpiece processing sheet after irradiation with active energy rays. Details of the method for measuring the adhesive strength are as described in the test examples below.

[0101] (4) Surface resistivity before irradiation with active energy rays In the workpiece processing sheet according to this embodiment, the surface resistivity of the adhesive layer before irradiation with active energy rays is 1×10 13 Ω / cm 2 It is preferable that the value is equal to or less than 1×10 12 Ω / cm 2 It is preferable that the value is 2×10 or less, and more preferably 2×10 11 Ω / cm 2 The lower limit of the surface resistivity of the pressure-sensitive adhesive layer before ultraviolet irradiation is not particularly limited, and is, for example, 1×10 7 Ω / cm 2The workpiece processing sheet according to this embodiment has the above-described surface resistivity, which makes it easier to effectively prevent the workpiece from being damaged by peeling electrification when the workpiece processing sheet is peeled off from the workpiece. Details of the method for measuring the surface resistivity are as described in the test examples below.

[0102] 5. 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.

[0103] 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, roll 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.

[0104] When the coating solution for forming the adhesive layer contains a crosslinking agent, the crosslinking reaction between the active energy radiation curable polymer (A) 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, and a crosslinked structure with the desired density can be formed in the adhesive layer. To sufficiently promote this crosslinking reaction, after laminating the adhesive layer on the substrate by the above-mentioned method, the obtained 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.

[0105] 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.

[0106] 6. How to use the workpiece processing sheet The workpiece processing sheet according to this embodiment can be used for processing a workpiece. That is, after the adhesive side of the workpiece processing sheet according to this embodiment is attached to one side of the workpiece, the workpiece can be processed on the workpiece processing sheet. Examples of such processing include backgrinding, dicing, expanding, and picking up. The dicing may be, for example, blade dicing using a rotating circular blade, laser dicing in which a semiconductor wafer is fully cut by irradiating it with laser light, or stealth dicing in which a modified layer is formed on the semiconductor wafer by irradiating it with laser light and then the semiconductor wafer is stretched to divide the semiconductor wafer at the modified layer. The workpiece processing sheet according to this embodiment can be used as a backgrinding sheet, dicing sheet, expanding sheet, picking up sheet, etc., depending on the type of processing.

[0107] Examples of workpieces that can be processed using the workpiece processing sheet according to this embodiment include semiconductor components such as semiconductor wafers and semiconductor packages, and glass components such as glass plates. As mentioned above, the workpiece processing sheet according to this embodiment can effectively suppress an increase in adhesion of the workpiece processing sheet to an active surface, even when the adhesive surface is attached to the active surface of a workpiece having an active surface. Therefore, the workpiece processing sheet according to this embodiment is suitable for use in processing workpieces having an active surface (especially the ground surface of a semiconductor wafer whose surface has been ground for less than 120 minutes). However, the workpiece processing sheet according to this embodiment can be attached to both workpieces having an active surface (especially the ground surface of a semiconductor wafer whose surface has been ground for less than 120 minutes) and ordinary workpieces without an active surface (especially the surface other than the ground surface of a semiconductor wafer whose surface has been ground for less than 120 minutes).

[0108] When the processing of the workpiece on the workpiece processing sheet according to this embodiment is completed and the processed workpiece is to be separated from the workpiece processing sheet, it is preferable to irradiate the adhesive layer of the workpiece processing sheet with active energy rays before the separation, which hardens the adhesive layer and effectively reduces the adhesive strength of the workpiece processing sheet to the processed workpiece, making it easier to separate the processed workpiece.

[0109] The active energy rays can be, for example, electromagnetic waves or charged particle beams having an energy quantum, and specifically, ultraviolet rays, electron beams, etc. are usable. Ultraviolet rays are particularly preferred because they are easy to handle. Ultraviolet rays can be irradiated using a high-pressure mercury lamp, a xenon lamp, an LED, etc., and the amount of ultraviolet irradiation is such that the illuminance is 1 mW / cm. 2 More than 1000mW / cm 2 The light intensity is preferably 10 mJ / cm or less. 2 More preferably, it is 80 mJ / cm or more. 2 It is preferable that the intensity is 150 mJ / cm or more, and more preferably 150 mJ / cm 2The light intensity is preferably 10,000 mJ / cm or more. 2 It is preferable that the concentration is not more than 5000 mJ / cm 2 It is preferable that the intensity is 2000 mJ / cm or less, and more preferably 2000 mJ / cm 2 On the other hand, the irradiation of electron beams can be carried out by an electron beam accelerator or the like, and the irradiation dose of the electron beams is preferably 10 krad or more and 1000 krad or less.

[0110] The workpiece processing sheet according to this embodiment is particularly preferably used in a method for manufacturing a machined workpiece, which includes the following steps: a grinding step for grinding the surface of the workpiece, an attachment step for attaching the workpiece processing sheet according to this embodiment to the ground surface of the workpiece, a dicing step for dicing the workpiece on the workpiece processing sheet to obtain chips by dividing the workpiece, an active energy ray irradiation step for irradiating the adhesive layer of the workpiece processing sheet with active energy rays, and a pick-up step for individually picking up the chips from the workpiece processing sheet.

[0111] The grinding process can be carried out using a conventionally known method. For example, the adhesive surface of a desired adhesive sheet (which may be the workpiece processing sheet according to this embodiment) is attached to one side of the workpiece, and the other side of the workpiece is ground on the adhesive sheet using a grinding device. The degree of grinding is selected according to the purpose, and for example, the workpiece is ground until its thickness and surface condition reach a predetermined level. After the grinding, the ground surface may be subjected to a conventionally known surface treatment.

[0112] In the subsequent attachment step, the adhesive surface of the workpiece processing sheet according to this embodiment is attached to the ground surface of the workpiece, and the specific method is not limited thereto. Here, the time from grinding the surface of the workpiece in the grinding step to attaching the workpiece may be within 120 minutes, particularly within 30 minutes, or even within 5 minutes. If the time is within 120 minutes, the ground surface of the workpiece remains activated. However, the workpiece processing sheet according to this embodiment can suppress excessive adhesion to such activated surfaces, allowing for good pickup in the pickup step described below.

[0113] The subsequent dicing step can be performed using a conventionally known method. That is, a dicing device is used to dice the workpiece on the workpiece processing sheet to obtain a plurality of chips. The type of dicing used here is not particularly limited, and may be, for example, blade dicing, laser dicing, stealth dicing, or the like.

[0114] The irradiation of active energy rays in the active energy ray irradiation step can be carried out by a conventionally known method. The type of active energy ray and the irradiation conditions are as described above.

[0115] The subsequent pickup process can also be performed using a conventionally known method. For example, a pickup device can be used to expand the workpiece processing sheet, push up the semiconductor chip from the backside of the workpiece processing sheet with a needle, and then use a suction collet to pick up the chip. The workpiece processing sheet according to this embodiment prevents excessive adhesion to the workpiece and chip, thereby avoiding problems such as being unable to pick up the chip, and achieving good pickup.

[0116] 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.

[0117] 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]

[0118] 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.

[0119] Example 1 (1) Preparation of 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. Both sides of the obtained EMAA film were then corona-treated. This produced the substrate.

[0120] (2) Preparation of adhesive composition 52 parts by mass of n-butyl acrylate, 20 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate were polymerized by solution polymerization to obtain a (meth)acrylic acid ester polymer.

[0121] The obtained (meth)acrylic acid ester polymer was reacted with methacryloyloxyethyl isocyanate (MOI) in an amount equivalent to 90 mol% of the 2-hydroxyethyl acrylate constituting the (meth)acrylic acid ester polymer to obtain an acrylic polymer (active energy ray curable polymer) having active energy ray curable groups introduced into its side chains. The weight average molecular weight (Mw) of the active energy ray curable polymer was measured by the method described below and was found to be 660,000.

[0122] A mixture of 35 parts by mass of the obtained active energy ray-curable polymer, 0.375 parts by mass of a trimethylolpropane adduct of 1,6-hexamethylene diisocyanate (manufactured by Tosoh Corporation, product name "Coronate HL") as a crosslinking agent, 0.47 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name "Irgacure 184") as a photopolymerization initiator, 1 part by mass of alkylene glycol-modified rosin ester (manufactured by Arakawa Chemical Industries, Ltd., product name "D-6250"), and hindered One part by mass of a mixed ester of 1,2,3,4-butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (N-methyl-type hindered amine stabilizer, manufactured by ADEKA Corporation, product name "ADEKA STAB LA-63P") was mixed in a solvent to obtain a coating solution of a pressure-sensitive adhesive composition (solid concentration 30% by mass).

[0123] (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.

[0124] (4) Preparation of adhesive sheet One side of the substrate obtained in step (1) was bonded to the adhesive layer side of the laminate obtained in step (3), and then the laminate was stored in a light-shielded environment at 23°C and 50% humidity for 10 days to obtain a workpiece processing sheet.

[0125] (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℃

[0126] [Examples 2 to 4 and Comparative Examples 1 to 5] A workpiece processing sheet was obtained in the same manner as in Example 1, except that the contents of the alkylene glycol-modified rosin ester, the hindered amine-based stabilizer, and the crosslinking agent were changed as shown in Table 1.

[0127] Example 5 A workpiece processing sheet was obtained in the same manner as in Example 1, except that 1.87 parts by mass of an ionic solid (manufactured by Nippon Carlit Co., Ltd., product name "CIL-H11") was added as an antistatic agent when preparing the adhesive composition.

[0128] Examples 6 to 8 A workpiece processing sheet was obtained in the same manner as in Example 5, except that the contents of the alkylene glycol-modified rosin ester, the hindered amine-based stabilizer, and the crosslinking agent were changed as shown in Table 1.

[0129] [Test Example 1] (Measurement of adhesive strength before irradiation with active energy rays) 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 strips, and the exposed adhesive surface of the pressure-sensitive 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% to prepare a measurement sample.

[0130] For the obtained measurement sample, 20 minutes after application to the silicon wafer, the workpiece processing sheet was peeled from the silicon wafer at a peel rate of 300 mm / min and a peel angle of 180° using a universal tensile tester (manufactured by Orientec Co., Ltd., product name "Tensilon UTM-4-100") at 23°C, and the adhesive strength (mN / 25 mm) to the silicon wafer was measured using the 180° peel method in accordance with JIS Z0237:2009. The measured adhesive strength values ​​obtained in this way are shown in Table 1 as pre-UV adhesive strength.

[0131] Furthermore, the adhesiveness to the non-active surface before irradiation with active energy rays was evaluated based on the above measured values ​​according to the following criteria. The results are also shown in Table 1. A: The pre-UV adhesive strength was 3000 mN / 25 mm or more. B: The pre-UV adhesive strength was 1000 mN / 25 mm or more and less than 3000 mN / 25 mm. C: Pre-UV adhesion was less than 1000 mN / 25 mm.

[0132] [Test Example 2] (Measurement of adhesive strength to active surface before irradiation with active energy rays) The workpiece processing sheets produced in the examples and comparative examples were cut into 25 mm wide strips. Using a grinding machine (manufactured by Disco Corporation, product name "DFG8540"), one side of a silicon wafer was ground until the thickness of the silicon wafer was 600 μm and a #2000 polished surface was obtained. The release sheet was peeled off from the strip-shaped workpiece processing sheet, and the exposed surface of the adhesive layer was attached to the activated surface (active surface) using a 2 kg rubber roller under an environment of 23 ° C. and 50% relative humidity. The sample was then left to stand for 20 minutes to prepare a measurement sample. The workpiece processing sheet was attached to the active surface within 5 minutes of grinding.

[0133] The measurement sample was stored in an environment at a temperature of 23°C and a relative humidity of 50% for 20 minutes.

[0134] After storage, the workpiece processing sheet was peeled from the silicon wafer using a universal tensile tester (manufactured by Orientec, product name "Tensilon UTM-4-100") at a peeling speed of 300 mm / min and a peeling angle of 180°, and the adhesive strength (mN / 25 mm) was measured using the 180° peeling method in accordance with JIS Z0237:2009. The measured adhesive strength obtained in this way is shown in Table 1 as the adhesive strength to the activated wafer before UV irradiation.

[0135] Furthermore, the above measured values ​​were compared with the following criteria to evaluate the adhesiveness to the active wafer before irradiation with active energy rays. A: The adhesive strength to the activated wafer before UV was 4000 mN / 25 mm or more. B: The adhesive strength to the activated wafer before UV was 3000 mN / 25 mm or more and less than 4000 mN. C: Pre-UV adhesion to active wafer was less than 3000 mN / 25 mm.

[0136] [Test Example 3] (Measurement of adhesive strength after irradiation of active energy rays on activated surface) The workpiece processing sheets produced in the examples and comparative examples were cut into 25 mm wide strips. Using a grinding machine (manufactured by Disco Corporation, product name "DFG8540"), one side of a silicon wafer was ground until the thickness of the silicon wafer was 600 μm and a #2000 polished surface was obtained. The release sheet was peeled off from the strip-shaped workpiece processing sheet, and the exposed surface of the adhesive layer was attached to the activated surface (active surface) using a 2 kg rubber roller under an environment of 23 ° C. and 50% relative humidity. The sample was then left to stand for 20 minutes to prepare a measurement sample. The workpiece processing sheet was attached to the active surface within 5 minutes of grinding.

[0137] The measurement sample was stored in an environment at a temperature of 23°C and a relative humidity of 50% for 7 days.

[0138] After storage, the adhesive layer was irradiated with ultraviolet (UV) light through the substrate using an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2010") (illuminance: 230 mW / cm 2 ,Light amount: 190mJ / cm 2 ), and the adhesive layer was cured.

[0139] Then, 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) was measured using the 180° peeling method in accordance with JIS Z0237: 2009. The measured adhesive strength values ​​obtained in this way are shown in Table 1 as adhesive strength against activated wafer after UV irradiation.

[0140] Furthermore, the above measured values ​​were compared with the following criteria to evaluate the adhesiveness of the active wafer after irradiation with active energy rays. A: The adhesive strength to the activated wafer after UV irradiation was 200 mN / 25 mm or less. B: The adhesive strength to the activated wafer after UV irradiation was more than 200 mN / 25 mm and 300 mN or less. C: The post-UV adhesive strength to the activated wafer was greater than 300 mN / 25 mm.

[0141] [Test Example 4] (Evaluation of dicing suitability) Using a grinding machine (Disco Corporation, product name "DFG8540"), one side of a silicon wafer was ground until the thickness of the silicon wafer became 150 μm and a #2000 polished surface was obtained. The release sheet was peeled off from the workpiece processing sheet manufactured in the Examples and Comparative Examples, and the exposed adhesive surface of the adhesive layer was attached to the activated ground surface (activated surface) using a laminator. This attachment was performed within 5 minutes of the grinding.

[0142] After the above-mentioned application, the substrate was stored for 20 minutes in an environment of a temperature of 23°C and a relative humidity of 50%, and then dicing was carried out under the following conditions. <Dicing conditions> Dicing equipment: Disco DFD-6362 Blade: Disco NBC-2H 2050 27HECC Blade width: 0.025~0.030mm Blade exposure: 0.640~0.760mm Blade rotation speed: 35,000 rpm ·Cutting speed: 60mm / sec Substrate cutting depth: 20 μm ·Cutting water amount: 1.0L / min ·Cutting water temperature: 20℃ Dicing size: 0.4mm square

[0143] After dicing, the obtained chips were visually inspected and the number of chips that had been blown off was counted. The results are shown in Table 1. Furthermore, the number of chips was compared with the following criteria to evaluate the dicing suitability. A: The number of chips that flew off was less than 0. B: The number of chips that flew off was 10 or more but less than 20. C: The number of chips that flew off was 20 or more.

[0144] [Test Example 5] (Evaluation of Pickup Suitability) Using a grinding machine (Disco Corporation, product name "DFG8540"), one side of a silicon wafer was ground until the thickness of the silicon wafer became 150 μm and a #2000 polished surface was obtained. The release sheet was peeled off from the workpiece processing sheet manufactured in the Examples and Comparative Examples, and the exposed adhesive surface of the adhesive layer was attached to the activated ground surface (activated surface) using a laminator. This attachment was performed within 5 minutes of the grinding.

[0145] After the above-mentioned application, the substrate was stored for 7 days in an environment of a temperature of 23°C and a relative humidity of 50%, and then dicing was carried out under the following conditions. <Dicing conditions> Dicing equipment: Disco DFD-6362 Blade: Disco NBC-2H 2050 27HECC Blade width: 0.025~0.030mm Blade exposure: 0.640~0.760mm Blade rotation speed: 35,000 rpm ·Cutting speed: 60mm / sec Substrate cutting depth: 20 μm ·Cutting water amount: 1.0L / min ·Cutting water temperature: 20℃ Dicing size: 10mm square

[0146] Furthermore, the adhesive layer of the workpiece processing sheet was irradiated with ultraviolet (UV) light through the substrate using an ultraviolet irradiation device (manufactured by Lintec Corporation, product name "RAD-2010") (illuminance: 230 mW / cm 2 ,Light amount: 190mJ / cm 2 ), and the adhesive layer was cured.

[0147] Next, we attempted to pick up one of the chips obtained by the dicing process, located near the center of the workpiece processing sheet when viewed from above, using a pickup device. Specifically, we pushed the chip up from the substrate side of the workpiece processing sheet to a height of 500 μm with a needle, while adsorbing the side of the chip opposite the workpiece processing sheet with a vacuum collet in an attempt to separate the chip from the workpiece processing sheet. This pickup operation was performed on 10 chips, and the number of chips that were successfully separated was counted. The results are shown in Table 1.

[0148] Furthermore, the number of particles was compared with the following criteria to evaluate the pick-up suitability. A: The number of chips that could be separated was 10. B: The number of separated chips was 1 or more and 9 or less. C: The number of separated chips was 0.

[0149] Test Example 6 (Measurement of surface resistivity before irradiation with active energy rays) The workpiece processing sheets produced in the examples and comparative examples were cut into a size of 10 cm x 10 cm to prepare measurement samples. The release sheet was peeled off from the measurement sample, and the surface resistivity (Ω / cm) of the exposed adhesive surface of the adhesive layer was measured using a surface resistivity meter (manufactured by Advantest Corporation, product name "R8252") in accordance with JIS K7194 under conditions of a temperature of 23°C, a relative humidity of 50%, and an applied voltage of 100 V. 2 The measurement results are shown in Table 1 as pre-UV surface resistivity.

[0150] Furthermore, the antistatic properties were evaluated based on the above measurement results in accordance with the following criteria. A: Surface resistivity is 1 x 10 11 Ω / cm 2 It was less than. B: Surface resistivity is 1 x 10 11 Ω / cm 2 That was all.

[0151] [Table 1]

[0152] As can be seen from Table 1, the workpiece processing sheets obtained in the examples exhibited good adhesive strength before active energy ray irradiation, whether they were attached to the inactive side of a silicon wafer or the active side of a silicon wafer. Furthermore, even when the workpiece processing sheets obtained in the examples were attached to the active side of a silicon wafer, they were able to sufficiently reduce their adhesive strength to the workpiece by active energy ray irradiation.

[0153] Furthermore, the workpiece processing sheets obtained in the examples were also excellent in dicing suitability and pick-up suitability. Note that the workpiece processing sheets according to Examples 5 to 8, in which the adhesive layer contained an antistatic agent, exhibited excellent antistatic properties. [Industrial Applicability]

[0154] The workpiece processing sheet according to the present invention is suitably used as a dicing sheet for workpieces having active surfaces.

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 containing an alkylene glycol-modified rosin ester and a hindered amine-based stabilizer, The workpiece processing sheet is intended to be attached to the ground surface of a workpiece within 120 minutes of grinding the surface of the workpiece. A workpiece processing sheet characterized by:

2. 2. The workpiece processing sheet according to claim 1, wherein the hindered amine stabilizer is an N-alkyl hindered amine stabilizer.

3. 2. The workpiece processing sheet according to claim 1, wherein the hindered amine stabilizer has a molecular weight of 500 or more.

4. 2. The workpiece processing sheet according to claim 1, wherein the weight average molecular weight of the alkylene glycol-modified rosin ester is 1,000 or more.

5. The workpiece processing sheet according to claim 1, characterized in that the active energy ray-curable adhesive is formed from an adhesive composition containing an acrylic polymer having an active energy ray-curable group introduced into its side chain, the alkylene glycol-modified rosin ester, and the hindered amine-based stabilizer.

6. The workpiece processing sheet according to claim 5, wherein the adhesive composition contains an antistatic agent.

7. a grinding step of grinding the surface of the workpiece; A pasting step of pasting the workpiece processing sheet according to any one of claims 1 to 6 onto the surface of the workpiece that has been ground; a dicing step of dicing the workpiece on the workpiece processing sheet to obtain a plurality of chips formed by dividing the workpiece; an active energy ray irradiation step of irradiating the pressure-sensitive adhesive layer of the workpiece processing sheet with active energy rays; a pick-up step of individually picking up the chips from the workpiece processing sheet; A method for manufacturing a machined workpiece, comprising:

8. 8. A method for manufacturing a machined workpiece according to claim 7, characterized in that the workpiece processing sheet is attached to the workpiece in the attaching step within 120 minutes of grinding the surface of the workpiece in the grinding step.

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