Sheet for workpiece processing and method for manufacturing processed workpiece

Abstract

Provided is a workpiece processing sheet capable of suppressing excessive increase in adhesion even with respect to an active surface of a workpiece and capable of achieving good workpiece processing. A sheet for processing a workpiece, which is provided with a base material and an adhesive layer laminated on one surface side of the base material, the adhesive layer comprising an active energy ray-curable adhesive containing a hindered amine stabilizer, and which is used to be adhered to the polished surface of the workpiece within 120 minutes from the polishing surface.

Description

Technical Field

[0001] The present invention relates to a workpiece processing sheet suitable for processing a workpiece such as a semiconductor wafer, and a method for manufacturing a processed workpiece using the workpiece processing sheet. The present invention particularly relates to a workpiece processing sheet suitable for processing a workpiece having a surface in an active state (hereinafter sometimes referred to as an "active surface"), and a method for manufacturing a processed workpiece using the workpiece processing sheet. Background Art

[0002] Semiconductor wafers such as silicon and gallium arsenide or various packages are manufactured in a large diameter state, cut (diced) into component small pieces (semiconductor chips) and peeled (picked up), and then transferred to the mounting process as the next process. At this time, the workpiece such as the semiconductor wafer is attached to the workpiece processing sheet with a substrate and an adhesive layer, and back grinding, dicing, cleaning, drying, expansion, picking up, assembly and other processes are performed.

[0003] In the back grinding process, after the workpiece is fixed on the workpiece processing sheet, the exposed surface of the workpiece is usually ground using a grinding device. In the cutting process, the ground workpiece is cut on the workpiece processing sheet and singulated into multiple chips. And in the picking process, the multiple chips obtained are picked up one by one from the workpiece processing sheet.

[0004] In the back grinding process, the workpiece with one side ground is sometimes re-attached to a new workpiece processing sheet before the grinding process. At this time, the surface on the adhesive layer side of the new workpiece processing sheet is attached to the ground surface (hereinafter sometimes referred to as "adhesive surface"), and the previous workpiece processing sheet is peeled off.

[0005] In recent years, the above-mentioned grinding, re-sticking and cutting processes are sometimes continuously performed in an assembly line. At this time, the workpiece processing sheet is immediately attached to the grinding surface of the workpiece after grinding.

[0006] Here, usually, the grinding surface of the workpiece just after grinding is in an activated state due to grinding. Therefore, when the workpiece processing sheet is attached immediately after grinding the workpiece, the workpiece processing sheet is attached to the active surface of the workpiece. At this time, since the active surface is active, the closeness between the workpiece and the workpiece processing sheet tends to increase excessively. In particular, the closeness has a tendency to increase the longer the time of the state of the workpiece and the workpiece processing sheet being stacked. In addition, when the workpiece and the workpiece processing sheet are excessively close in this way, in the subsequent picking process, since the obtained chip is in a state of being strongly attached to the workpiece processing sheet, it cannot be picked up well.

[0007] Generally, from the perspective of being able to pick up well, a workpiece processing sheet having an adhesive layer composed of an adhesive having active energy ray curability can also be used. In this case, by irradiating the adhesive layer with active energy rays just before picking up, the adhesive layer is cured, thereby reducing the adhesion to the chip and making it easier to separate the chip. However, even when such a workpiece processing sheet is used, it is still difficult to avoid the problem of not being able to pick up well as described above.

[0008] In order to solve the above-mentioned problem of improving the adhesion to the active surface of the workpiece, Patent Document 1 discloses a workpiece processing sheet including an active energy ray-curable adhesive layer containing an alkanediol-modified rosin ester as a tackifier. Prior art literature Patent Literature

[0009] Patent Document 1: Japanese Patent No. 7254669 Summary of the invention Technical Problems to be Solved by the Invention

[0010] A certain effect can be obtained in reducing the adhesion to the active surface of the workpiece by using the workpiece processing sheet disclosed in Patent Document 1. However, there is a demand to further reduce the adhesion and achieve better workpiece processing.

[0011] The present invention has been made in view of the above actual situation, and an object of the present invention is to provide a workpiece processing sheet capable of suppressing excessive increase in adhesion even to an active surface of a workpiece and enabling good workpiece processing, and a method for manufacturing a processed workpiece using the workpiece processing sheet. Technical means to solve technical problems

[0012] In order to achieve the above-mentioned purpose, first, the present invention provides a workpiece processing sheet, which has a substrate and an adhesive layer laminated on one side of the substrate, and the workpiece processing sheet is characterized in that the adhesive layer is composed of an active energy ray-curable adhesive containing a hindered amine stabilizer, and the workpiece processing sheet is used to adhere to the polished surface of the workpiece within 120 minutes from the start of polishing the surface (Invention 1).

[0013] In the workpiece processing sheet of the above invention (Invention 1), the adhesive layer is composed of an active energy ray-curable adhesive containing a hindered amine stabilizer, so that even when attached to the active surface of the workpiece, the adhesive layer can be well cured by irradiation with active energy rays, thereby sufficiently reducing the adhesive force. Therefore, the workpiece processing sheet can be easily separated from the workpiece even after being attached to the active surface of the workpiece and stored for a long time.

[0014] Second, the present invention provides a workpiece processing sheet, which comprises a substrate and an adhesive layer laminated on one side of the substrate, the workpiece processing sheet being characterized in that the adhesive layer is composed of an active energy ray-curable adhesive containing a hindered amine stabilizer, and for a stack of the workpiece processing sheet and the silicon wafer obtained by attaching the surface of the adhesive layer opposite to the substrate to the polished surface of a silicon wafer within 20 minutes from the polishing surface, when the adhesion of the workpiece processing sheet to the silicon wafer after irradiating the adhesive layer with ultraviolet rays immediately after the attachment is set to F0, and the adhesion of the workpiece processing sheet to the silicon wafer after irradiating the adhesive layer with ultraviolet rays after being stored for 7 days from the start of the attachment is set to F7, the adhesion increase rate calculated as the ratio of F7 to F0 (F7 / F0) is less than 2.0 (Invention 2).

[0015] In the workpiece processing sheet of the above invention (Invention 2), since the adhesive layer is composed of an active energy ray-curable adhesive containing a hindered amine stabilizer and exhibits the above-mentioned adhesive force increase rate, even when attached to the active surface of the workpiece, the adhesive layer can be well cured by irradiating active energy rays, thereby sufficiently reducing the adhesive force. Therefore, the workpiece processing sheet can be easily separated from the workpiece even after being attached to the active surface of the workpiece and stored for a long time.

[0016] In the above inventions (Inventions 1 and 2), the hindered amine stabilizer is preferably an N-alkyl hindered amine stabilizer (Invention 3).

[0017] In the above inventions (Inventions 1 to 3), 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 a side chain and the hindered amine stabilizer (Invention 4).

[0018] Third, the present invention provides a method for manufacturing a processed workpiece, characterized in that the manufacturing method comprises: a grinding step for grinding the surface of the workpiece; an attaching step for attaching the workpiece processing sheet (Inventions 1 to 4) to the ground surface of the workpiece; a cutting step for cutting the workpiece on the workpiece processing sheet to obtain a plurality of chips obtained by singulating the workpiece; an active energy ray irradiation step for irradiating the adhesive layer of the workpiece processing sheet with active energy rays; and a picking up step for picking up the chips one by one from the workpiece processing sheet (Invention 5).

[0019] In the above invention (Invention 5), it is preferred that the workpiece processing sheet be attached to the workpiece in the attaching step within 120 minutes from the start of grinding the surface of the workpiece in the grinding step (Invention 6). Effects of the Invention

[0020] The workpiece processing sheet of the present invention can suppress excessive increase in adhesion even to the active surface of the workpiece and can achieve good workpiece processing. In addition, the processing workpiece can be well manufactured by the manufacturing method of the present invention. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described. The workpiece processing sheet of the present embodiment comprises 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 a hindered amine stabilizer.

[0022] Furthermore, as a first embodiment, the workpiece processing sheet is used to be attached to the above-mentioned ground surface of the workpiece within 120 minutes from the start of surface grinding.

[0023] In addition, as a second embodiment, for a workpiece processing sheet, for a stack of the workpiece processing sheet and the silicon wafer obtained by adhering the surface of the adhesive layer opposite to the substrate to the polished surface of the silicon wafer within 20 minutes from the start of the polishing surface, the following conditions are satisfied.

[0024] First, the adhesive force of the workpiece processing sheet to the silicon wafer after the adhesive layer is irradiated with ultraviolet rays immediately after the attachment is defined as F0.

[0025] Furthermore, the adhesive force of the workpiece processing sheet to the silicon wafer after irradiating the adhesive layer with ultraviolet rays after storage for 7 days from the start of the sticking was defined as F7.

[0026] Under the above circumstances, in the workpiece processing sheet of the second embodiment, the adhesive force increase rate calculated as the ratio of the above F7 to the above F0 (F7 / F0) is 2.0 or less.

[0027] In the workpiece processing sheet of the present embodiment including the first embodiment and the second embodiment, the adhesive layer is made of an active energy ray-curable adhesive, and the adhesive layer is cured by irradiating active energy rays, thereby reducing the adhesive force to the workpiece. Therefore, when it is necessary to separate the workpiece processing sheet of the present embodiment from the workpiece, it is possible to suppress the damage of the workpiece or the adhesion of part of the adhesive constituting the adhesive layer to the workpiece (residual adhesive), and the separation can be easily performed.

[0028] Furthermore, in the workpiece processing sheet of the present embodiment, by making the active energy ray-curable adhesive contain a hindered amine stabilizer, even when the workpiece processing sheet is attached to the active surface of the workpiece and further stored for a long time in the attached state, it is possible to suppress excessive increase in adhesion to the workpiece. Therefore, the workpiece processing sheet can be easily separated from the workpiece by irradiating the active energy ray as described above.

[0029] The reason why the workpiece processing sheet of the present embodiment suppresses an excessive increase in adhesion to the workpiece is presumably as follows, but the reason is not limited to this.

[0030] First, as a mechanism for the surface activation of a workpiece, it is believed that by polishing the surface of the workpiece, the inactive part existing on the surface is removed, and the active part inside is exposed. For example, when the workpiece is a silicon wafer, it is believed that under normal conditions, the surface of the silicon wafer is oxidized to form inactive SiO 2 If the surface of such a silicon wafer is polished, the SiO 2 The film is removed, exposing unoxidized silicon atoms. In addition, the exposed silicon atoms sometimes react with the cleaning water used in the back grinding process or moisture in the atmosphere to partially form Si-H or Si-OH structures. 2 The surface exposed by the film is in a state where it is easy to interact with the adhesive surface of a normal workpiece processing sheet and to form a chemical bond with the adhesive constituting the adhesive layer.

[0031] In addition, it is believed that grinding the surface of the workpiece causes free radicals to be generated on the surface, so that the surface is in an activated state. For example, on the ground surface, free radicals (R·) are first generated due to hydrogen being taken from the RH group. Then, a part of the free radicals (R·) reacts with oxygen molecules in the air to generate peroxy radicals (ROO·). And, a part of it takes hydrogen from the RH group to generate hydroperoxide (hydroperoxide) (ROOH) and free radicals (R·). Further, a part of the generated hydroperoxide (ROOH) decomposes to generate oxygen radicals (RO·) and hydroxyl radicals (·OH). In this way, the surface that generates a large number of free radicals is in a state where it is easy to interact with the adhesive surface of the usual workpiece processing sheet and is easy to produce chemical bonds with the adhesive constituting the adhesive layer.

[0032] However, in the workpiece processing sheet of the present embodiment, it is believed that the hindered amine stabilizer or the stable free radicals generated in the system from the hindered amine stabilizer captures the free radicals generated as described above instead of activating them, thereby suppressing the interaction with the active energy ray-curable adhesive or the generation of chemical bonds. As a result, the workpiece processing sheet of the present embodiment can effectively suppress the increase in adhesion with the active surface.

[0033] In particular, it is believed that hindered amine stabilizers can capture at least three of the above-mentioned multiple free radicals, namely R·, RO· and ROO·. In contrast, other stabilizers (hindered phenol stabilizers, phosphite stabilizers, etc.) can capture fewer types of free radicals, or cannot capture free radicals at all. The workpiece processing sheet of this embodiment can effectively suppress the increase in adhesion to the active surface by using a hindered amine stabilizer.

[0034] In addition, after the hindered amine stabilizer captures the free radical (bonds with the free radical), it reacts to disconnect the free radical part again and regenerates as a hindered amine stabilizer. Therefore, the hindered amine stabilizer can continuously exert its effect as a stabilizer. In addition, such a regeneration effect does not occur in the hindered phenol compounds used in the past. From this perspective, the workpiece processing sheet of this embodiment can effectively suppress the increase in adhesion with the active surface.

[0035] In addition, in the specification of the present application, the surface of the workpiece being in an activated state refers to a state within 120 minutes from the start of grinding the surface of the workpiece, preferably a state within 30 minutes from the start of grinding the surface of the workpiece, and more preferably a state within 5 minutes from the start of grinding the surface of the workpiece.

[0036] In addition, the shelf life of the stack of the workpiece and the workpiece processing sheet after the workpiece processing sheet of this embodiment is attached to the active surface of the workpiece can be set according to the purpose of use. Generally, the shelf life is mostly 0 to 500 days, particularly mostly 1 to 90 days, and further mostly 7 to 30 days.

[0037] 1. Substrate The substrate of the present embodiment is not particularly limited as long as it can play the required function when using the workpiece processing sheet. However, the substrate of the present embodiment is particularly preferably composed of a resin, and as an example of the resin, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate can be listed; polyolefin resins such as polyethylene, polypropylene, polybutene, polybutadiene, polymethylpentene, ethylene-norbornene copolymer, and norbornene resin; ethylene-vinyl acetate copolymer; ethylene-(meth) acrylic acid copolymer, ethylene-(meth) methyl acrylate copolymer, and other ethylene-(meth) acrylic acid ester copolymers and other ethylene copolymer resins; polyvinyl chloride, vinyl chloride copolymers and other polyvinyl chloride resins; (meth) acrylic acid ester copolymers; polyurethane; polyimide; polystyrene; polycarbonate; fluororesin, etc. In addition, the resin constituting the substrate can be a modified resin such as a resin obtained by cross-linking the above-mentioned resin or an ionomer of the above-mentioned resin. In addition, "(meth) acrylic acid" in this specification 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".

[0038] The substrate of this embodiment may be a single-layer film composed of the above-mentioned resin, or may be a laminated film in which a plurality of such films are laminated. In the laminated film, the materials constituting each layer may be of the same type or of different types.

[0039] The substrate may contain various additives such as flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, ion traps, etc. The content of these additives is not particularly limited, but is preferably within a range in which the substrate can exert the desired function.

[0040] Furthermore, the substrate preferably has transparency to active energy rays. By using such a substrate, even when the adhesive layer is irradiated with active energy rays through the substrate, the adhesive layer can be easily cured well.

[0041] Furthermore, in order to improve the adhesion with the adhesive layer, the surface of the substrate on which the adhesive layer is laminated may be subjected to a surface treatment such as primer treatment, corona treatment, or plasma treatment.

[0042] The thickness of the substrate can be appropriately set according to the method of using the workpiece processing sheet, and is, for example, preferably 200 μm or less, particularly preferably 150 μm or less. In addition, the thickness of the substrate is preferably 10 μm or more, particularly preferably 25 μm or more.

[0043] 2. Adhesive layer As described above, the adhesive layer of the present embodiment is composed of an active energy ray-curable adhesive containing a hindered amine stabilizer.

[0044] Examples of the adhesive are not particularly limited, and include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, etc. Among them, acrylic adhesives are preferably used because they are easy to form an active energy ray-curable adhesive and are easy to exert the required adhesive force.

[0045] In addition, as the above-mentioned active energy ray curing adhesive, it can be a polymer with active energy ray curing as the main component, or a mixture of a non-active energy ray curing polymer (a polymer without active energy ray curing) and a monomer and / or oligomer having at least one active energy ray curing group as the main component. Further, the active energy ray curing adhesive can also be a mixture of a polymer with active energy ray curing and a monomer and / or oligomer having at least one active energy ray curing group. Among these components, as the active energy ray curing adhesive of the present embodiment, from the perspective of being able to suppress the adverse effects caused by excessive rise in adhesion even after heat treatment and being easy to carry out good workpiece separation by using a trigger (trigger) to reduce adhesion, it is preferred to use a polymer with active energy ray curing (particularly an acrylic polymer with active energy ray curing) as the main component.

[0046] The above-mentioned 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 the side chain (hereinafter, sometimes referred to as "active energy ray-curable polymer (A)"). In this case, the active energy ray-curable adhesive of the present embodiment is preferably formed of an adhesive composition containing an acrylic polymer having an active energy ray-curable group introduced into the side chain (active energy ray-curable polymer (A)) and a hindered amine stabilizer.

[0047] (1) Active energy ray-curable polymer (A) The active energy ray-curable polymer (A) is preferably obtained by reacting a (meth)acrylate polymer (a1) having a monomer unit containing a functional group with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group.

[0048] The functional group-containing monomer is preferably a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, a carboxyl group, an amino group, an amide group, a benzyl group, or a glycidyl group in the molecule. Among them, a monomer containing a hydroxyl group as a functional group (hydroxyl group-containing monomer) is preferably used.

[0049] Examples of the hydroxyl-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. Among them, at least one of 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate is preferably used. In addition, these hydroxyl-containing monomers may be used alone or in combination of two or more.

[0050] Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These carboxyl group-containing monomers may be used alone or in combination of two or more.

[0051] Examples of the amino group-containing monomer or amide group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. These monomers may be used alone or in combination of two or more.

[0052] The (meth)acrylate polymer (a1) preferably contains 5% by mass or more of structural units derived from the above-mentioned functional group-containing monomers, and particularly preferably contains 10% by mass or more of structural units derived from the above-mentioned functional group-containing monomers. In addition, the (meth)acrylate polymer (a1) preferably contains 40% by mass or less of structural units derived from the above-mentioned functional group-containing monomers, and particularly preferably contains 35% by mass or less of structural units derived from the above-mentioned functional group-containing monomers. By making the (meth)acrylate polymer (a1) contain the functional group-containing monomers in the above range, it is easy to form the desired active energy ray-curable polymer (A).

[0053] From the viewpoint of easily forming an adhesive having the desired properties, the (meth)acrylate polymer (a1) preferably contains an alkyl (meth)acrylate as a monomer unit constituting the (meth)acrylate polymer (a1). The alkyl (meth)acrylate is preferably an alkyl (meth)acrylate having an alkyl group with 1 to 18 carbon atoms, and particularly preferably an alkyl (meth)acrylate having 1 to 8 carbon atoms.

[0054] As specific examples of the above-mentioned alkyl (meth)acrylates, 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, stearyl (meth)acrylate, etc. can be listed. These alkyl (meth)acrylates can be used alone or in combination of two or more. Among the above-mentioned alkyl (meth)acrylates, 2-ethylhexyl acrylate is preferably used.

[0055] The (meth)acrylate polymer (a1) preferably contains 20% by mass or more of structural units derived from the above-mentioned alkyl (meth)acrylate, and particularly preferably contains 30% by mass or more of structural units derived from the above-mentioned alkyl (meth)acrylate. In addition, the (meth)acrylate polymer (a1) preferably contains 95% by mass or less of structural units derived from the above-mentioned alkyl (meth)acrylate, and particularly preferably contains 85% by mass or less of structural units derived from the above-mentioned alkyl (meth)acrylate. By making the (meth)acrylate polymer (a1) contain the above-mentioned range of alkyl (meth)acrylate, the workpiece processing sheet can easily exert the required adhesive force.

[0056] The (meth)acrylate polymer (a1) may contain other monomers as monomer units constituting the (meth)acrylate polymer (a1), in addition to the above-mentioned functional group-containing monomer and the (meth)acrylate alkyl ester.

[0057] Examples of the other monomers include nitrogen atom-containing monomers; alkoxy-containing alkyl (meth)acrylates such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate; (meth)acrylates having an aliphatic ring such as cyclohexyl (meth)acrylate; (meth)acrylates having an aromatic ring such as phenyl (meth)acrylate; non-crosslinking acrylamides such as (meth)acrylamide and N,N-dimethyl (meth)acrylamide; non-crosslinking (meth)acrylates having a tertiary amino group such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; vinyl acetate; styrene, and the like.

[0058] Examples of the nitrogen atom-containing monomers include monomers having an amino group, monomers having an amide group, monomers having a nitrogen-containing heterocyclic ring, etc. Further, examples of monomers having a nitrogen-containing heterocyclic ring include N-(methyl)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(methyl)acryloylpyrrolidone, N-(methyl)acryloylpiperidine, N-(methyl)acryloylpyrrolidine, N-(methyl)acryloylaziridine, aziridinylethyl(methyl)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinyl-o-phenylimide.

[0059] The (meth)acrylate polymer (a1) preferably uses a monomer having a homopolymer glass transition temperature (Tg) of greater than 10° C. as a monomer unit constituting the (meth)acrylate polymer (a1). Examples of such monomers include vinyl acetate, N-(meth)acryloylmorpholine, and methyl methacrylate. When the above monomers are used, the (meth)acrylate polymer (a1) preferably contains 10% by mass or more and 60% by mass or less of a structural unit derived from the above monomer.

[0060] The polymerization form of the (meth)acrylate polymer (a1) may be a random copolymer or a block copolymer. The polymerization method is not particularly limited, and the polymerization can be carried out by a common polymerization method, for example, a solution polymerization method.

[0061] The active energy ray-curable polymer (A) can be obtained by reacting the (meth)acrylate polymer (a1) having a monomer unit containing a functional group with the unsaturated group-containing compound (a2) having a functional group bonded to the functional group.

[0062] The functional group of the unsaturated group-containing compound (a2) can be appropriately selected according to the type of functional group of the functional group-containing monomer unit of the (meth)acrylate polymer (a1). For example, when the functional group of the (meth)acrylate polymer (a1) is a hydroxyl 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 aziridine group, and when the functional group of the (meth)acrylate 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 aziridine group.

[0063] In addition, in the above-mentioned unsaturated group-containing compound (a2), one molecule contains at least one active energy ray-polymerizable carbon-carbon double bond, preferably contains 1 to 6 active energy ray-polymerizable carbon-carbon double bonds, and further preferably contains 1 to 4 active energy ray-polymerizable carbon-carbon double bonds. Specific examples of such unsaturated group-containing compounds (a2) include 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-(2-methacryloyloxyethyloxy)ethyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate, m-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; acryloyl monoisocyanate compounds obtained by the reaction of a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate; acryloyl monoisocyanate compounds obtained by the reaction of 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.

[0064] The unsaturated group-containing compound (a2) is preferably used at a ratio of 50 mol% or more, particularly preferably at a ratio of 60 mol% or more, and further preferably at a ratio of 70 mol% or more, relative to the molar number of the functional group-containing monomer of the (meth)acrylate polymer (a1). In addition, the unsaturated group-containing compound (a2) is preferably used at a ratio of 95 mol% or less, particularly preferably at a ratio of 93 mol% or less, and further preferably at a ratio of 90 mol% or less, relative to the molar number of the functional group-containing monomer of the (meth)acrylate polymer (a1).

[0065] In the reaction between the (meth)acrylate polymer (a1) and the unsaturated group-containing compound (a2), the reaction temperature, pressure, solvent, time, presence or absence of a catalyst, and the type of catalyst can be appropriately selected according to the combination of the functional groups of the (meth)acrylate polymer (a1) and the functional groups of the unsaturated group-containing compound (a2). Thus, the functional groups present in the (meth)acrylate 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)acrylate polymer (a1), thereby obtaining an active energy ray-curable polymer (A).

[0066] The weight average molecular weight (Mw) of the active energy ray curable polymer (A) obtained in this way is preferably 10,000 or more, particularly preferably 150,000 or more, and further preferably 200,000 or more. In addition, the weight average molecular weight (Mw) is preferably 1.5 million or less, particularly preferably 1 million or less. In addition, the weight average molecular weight (Mw) in this specification is a value calculated using standard polystyrene measured by gel permeation chromatography (GPC method).

[0067] (2) Hindered amine stabilizers The hindered amine stabilizer in this specification 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.

[0068] In addition, as hindered amine stabilizers, there are generally the following stabilizers: N-alkyl hindered amine stabilizers, which are compounds having a structure in which one or two or more alkyl groups are bonded to the nitrogen atom of the 2,2,6,6-tetramethylpiperidine skeleton in the molecule; N-alkoxy hindered amine stabilizers, which are compounds having a structure in which one or two or more alkoxy groups are bonded to the nitrogen atom of the 2,2,6,6-tetramethylpiperidine skeleton in the molecule; NH-type hindered amine stabilizers, which are compounds having a structure in which one or two or more hydrogen atoms are bonded to the nitrogen atom of the 2,2,6,6-tetramethylpiperidine skeleton in the molecule. In the workpiece processing sheet of the present embodiment, any of the above compounds can be used to obtain good effects, but from the perspective of being easy to separate the workpiece even after long-term storage in a state of being attached to the active surface of the workpiece, it is preferred to use an N-alkyl hindered amine stabilizer.

[0069] Examples of the alkyl group in the above-mentioned N-alkyl hindered amine stabilizer include methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, n-octyl and the like. Among them, methyl is preferred from the viewpoint of being easy to separate from the workpiece even after long-term storage in a state of being attached to the active surface of the workpiece.

[0070] 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, p,p-toluenesulfonylaminodiphenylamine, N-phenyl-N'-(3-methacryloyloxy-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 diphenylamine, polycondensation product of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, poly[[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidinyl)imino]], N,N'-bis(3-aminopropyl)ethylenediamine and 2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidinyl)amino]-6 1,2,3,4-Butanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidyl) ester, 1,2,3,4-butanetetracarboxylic acid tetra(2,2,6,6-tetramethyl-4-piperidyl) ester, 1,2,3,4-but ...1,2,2,6,6-pentamethyl-4-piperidyl) ester, 1,2,3,4-butanetetracarboxylic acid tetra(2,2,6,6-tetramethyl-4-piperidyl) ester, 1,2,3,4-butanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidyl) ester, 1,2,3,4-butanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-piperidyl) ester, 1,2,3,4-butanetetracarboxylic acid tetra(1,2,2,6,6-pentamethyl-4-pi A mixed ester of carboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and 1-tridecanol, a mixed ester of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 1-tridecanol, 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, a mixed ester 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.5] Undecane mixed esters, (2,2,6,6-tetramethylene-4-piperidinyl)-2-propenecarboxylate, (1,2,2,6,6-pentamethyl-4-piperidinyl)-2-propenecarboxylate, etc.

[0071] Among the above specific examples, a mixed ester of 1,2,3,4-butanetetracarboxylic acid, 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 is preferably used as an N-alkyl hindered amine stabilizer.

[0072] In addition, the molar mass of the hindered amine stabilizer is preferably 200 g / mol or more, particularly preferably 600 g / mol or more, and further preferably 1000 g / mol or more. In addition, the molar mass is preferably 10000 g / mol or less, particularly preferably 5000 g / mol or less, and further preferably 3000 g / mol or less. By setting the molar mass of the hindered amine stabilizer to the above range, even after long-term storage in a state of being attached to the active surface of the workpiece, it is still easy to separate the workpiece.

[0073] The content of the hindered amine stabilizer in the adhesive composition is preferably 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, and further preferably 1.0 parts by mass or more relative to 100 parts by mass of an acrylic polymer having an active energy ray-curable group introduced into the side chain (active energy ray-curable polymer (A)). In addition, the content is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and further preferably 15 parts by mass or less. By making the content of the hindered amine stabilizer within the above range, it is easy to separate the workpiece even after long-term storage in a state of being attached to the active surface of the workpiece.

[0074] (3) Cross-linking agent The above-mentioned adhesive composition also preferably contains a crosslinking agent. By making the adhesive composition contain a crosslinking agent, in the adhesive layer, the active energy ray-curable polymer (A) is crosslinked to form a good three-dimensional network structure. Thus, the cohesive force of the obtained adhesive is further increased, and the generation of residual glue on the workpiece separated from the workpiece processing sheet after irradiation with active energy rays can be effectively suppressed. In addition, when the adhesive composition contains a crosslinking agent, the active energy ray-curable polymer (A) preferably contains the above-mentioned functional group-containing monomer as a monomer unit constituting the polymer, and particularly preferably contains a functional group-containing monomer having a high reactivity with the crosslinking agent used as a monomer unit constituting the polymer.

[0075] Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, aziridine crosslinking agents, hydrazine crosslinking agents, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, ammonium salt crosslinking agents, etc. These crosslinking agents can be selected according to the functional group from the functional group-containing monomer possessed by the acrylic copolymer. In addition, these crosslinking agents can be used alone or in combination of two or more.

[0076] The isocyanate crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and their biuret bodies and isocyanurate bodies; and adducts as reactants with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among them, the isocyanurate body of hexamethylene diisocyanate is preferably used, and at least one of the isocyanurate trimer of 1,6-hexamethylene diisocyanate, trimethylolpropane-modified toluene diisocyanate, and trimethylolpropane-modified hexamethylene diisocyanate is particularly preferably used.

[0077] When the above-mentioned adhesive composition contains a crosslinking agent, relative to 100 parts by mass of active energy ray-curable polymer (A), the content of the crosslinking agent in the adhesive composition is preferably 0.01 parts by mass or more, particularly preferably 0.1 parts by mass or more, and further preferably 0.4 parts by mass or more. In addition, the content is preferably 20 parts by mass or less, particularly preferably 5 parts by mass or less. By making the content of the crosslinking agent more than 0.01 parts by mass, it is easy to improve the cohesive force of the adhesive layer after irradiation with active energy rays, thereby, it is possible to effectively suppress residual glue. In addition, by making the content of the crosslinking agent less than 20 parts by mass, the degree of crosslinking becomes appropriate, and the adhesive layer easily exerts the required adhesion.

[0078] (4) Photopolymerization initiator The adhesive composition in this embodiment preferably contains a photopolymerization initiator. When the adhesive composition contains a photopolymerization initiator, the polymerization curing time and the light irradiation amount when the adhesive layer is cured by irradiating active energy rays can be reduced.

[0079] Examples of the photopolymerization initiator include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin benzoic acid methyl ester, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzil, dibenzil, diacetyl, β-chloroanthraquinone, ( 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane-1-one), (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, N,N-diethyldithiocarbamate 2-benzothiazolyl ester, oligomeric {2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, 2,2-dimethoxy-1,2-diphenylethane-1-one, etc. Among them, at least one of 1-hydroxycyclohexyl phenyl ketone and (2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane-1-one) is preferably used. The above-mentioned photopolymerization initiators can be used alone or in combination of two or more.

[0080] When the above-mentioned adhesive composition contains a photopolymerization initiator, relative to 100 parts by mass of active energy ray-curable polymer (A), the content of the photopolymerization initiator in the adhesive composition is preferably 0.1 parts by mass or more, particularly preferably 1 parts by mass or more. In addition, the content is preferably 20 parts by mass or less, particularly preferably 5 parts by mass or less. By making the content of the photopolymerization initiator in the above-mentioned range, the adhesive layer can be effectively cured by irradiating active energy rays, thereby, it is easy to make the workpiece processing sheet to the adhesion of the adherend well reduced.

[0081] (5) Other ingredients The adhesive composition may contain necessary additives such as silane coupling agents, antistatic agents, tackifiers, antioxidants, softeners, fillers, and refractive index adjusters, as long as the above effects of the workpiece processing sheet of this embodiment are not impaired.

[0082] (6) Method for preparing adhesive composition The adhesive composition in this embodiment can be prepared by preparing an active energy ray-curable polymer (A), mixing the obtained active energy ray-curable polymer (A), a hindered amine stabilizer, a cross-linking agent as required, a photopolymerization initiator, and a desired additive. At this time, a diluting solvent can also be added as required to obtain a coating liquid of the adhesive composition.

[0083] As the above-mentioned dilution solvent, for example, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane 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; cellosolve-type solvents such as ethyl cellosolve, etc. can be used.

[0084] As long as it is the range that can be coated, the concentration and viscosity of the coating solution prepared by the above method are not particularly limited, and can be appropriately selected according to the situation. For example, dilution is performed in a manner such that the concentration of the adhesive composition is more than 10% by mass and less than 60% by mass. In addition, it is not necessary to add a diluting solvent when obtaining the coating solution. If the adhesive composition is a viscosity that can be coated, then a diluting solvent may not be added. At this time, the adhesive composition is a coating solution in which the polymerization solvent of the acrylic copolymer (a1) is directly used as a diluting solvent.

[0085] (7) Thickness of adhesive layer The thickness of the adhesive layer in this embodiment is preferably 1 μm or more, particularly preferably 3 μm or more, and more preferably 4 μm or more. By making the thickness of the adhesive layer 1 μm or more, the workpiece processing sheet is easy to exert good adhesion and easy to suppress chip scattering. In addition, the thickness is preferably 75 μm or less, particularly preferably 30 μm or less, and more preferably 20 μm or less. By making the thickness of the adhesive layer 75 μm or less, it is easy to separate the workpiece.

[0086] 3. Other components In the workpiece processing sheet of the present embodiment, before the surface of the adhesive layer opposite to the substrate (adhesive surface) is attached to the workpiece, a release sheet may be laminated on the surface for the purpose of protecting the surface.

[0087] The composition of the release sheet is optional, and examples thereof include a sheet obtained by subjecting a plastic film to a release treatment using a release agent or the like. Specific examples of the plastic film include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene or polyethylene. As the release agent, silicone-based, fluorine-based, long-chain alkane-based, and rubber-based films can be used, and silicone-based films are preferred because they are inexpensive and can provide stable performance.

[0088] The thickness of the release sheet is not particularly limited, and may be, for example, 16 μm or more and 250 μm or less.

[0089] In addition, in the workpiece processing sheet of the present embodiment, an adhesive layer can be stacked on the surface of the adhesive layer on the opposite side to the substrate. At this time, the workpiece processing sheet of the present embodiment can be used as a cutting and solidifying chip. In this sheet, by attaching a workpiece on the surface of the adhesive layer on the opposite side to the adhesive layer, the workpiece and the adhesive layer are cut together, thereby obtaining a chip stacked with a singulated adhesive layer. The chip can be easily fixed on an object equipped with the chip through the singulated adhesive layer. As the material constituting the above-mentioned adhesive layer, it is preferred 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.

[0090] Furthermore, in the workpiece processing sheet of the present embodiment, a protective film forming layer can be stacked on the adhesive surface of the adhesive layer. In this case, the workpiece processing sheet of the present embodiment can be used as a protective film forming sheet and a cutting sheet. In such a sheet, by attaching a workpiece to the surface of the protective film forming layer opposite to the adhesive layer, and cutting the workpiece together with the protective film forming layer, a chip stacked with a singulated protective film forming layer can be obtained. As the workpiece, it is preferred to use a workpiece having a circuit formed on a single surface, in which case a protective film forming layer is usually stacked on the surface opposite to the surface on which the circuit is formed. By curing the singulated protective film forming layer at a specified time, a protective film with sufficient durability can be formed on the chip. The protective film forming layer is preferably composed of an uncured curable adhesive.

[0091] 4. Physical properties of workpiece processing sheets (1) Adhesion strength increase rate The workpiece processing sheet of this embodiment (particularly the second embodiment) preferably satisfies the above-mentioned conditions of the adhesive force increase rate. That is, it preferably satisfies the following conditions.

[0092] First, it is assumed that a laminate of the workpiece processing sheet and the silicon wafer is obtained by attaching the surface of the adhesive layer opposite to the substrate to the polished surface of the silicon wafer within 20 minutes from the start of surface polishing.

[0093] Furthermore, the adhesive force of the workpiece processing sheet to the silicon wafer after the adhesive layer was irradiated with ultraviolet rays immediately after the attachment was defined as F0.

[0094] Furthermore, the adhesive force of the workpiece processing sheet to the silicon wafer after irradiating the adhesive layer with ultraviolet rays after storage for 7 days from the start of the sticking was defined as F7.

[0095] In the above case, the adhesion increase rate calculated by the ratio of the above F7 to the above F0 (F7 / F0) is preferably 2.0 or less, particularly preferably 1.8 or less, and further preferably 1.5 or less. Thus, even after long-term storage in a state of being attached to the active surface of the workpiece, it is easy to separate the workpiece. In addition, the lower limit of the adhesion increase rate is not particularly limited, for example, preferably 0.9 or more.

[0096] The details of the method for measuring the above-mentioned adhesive forces F0 and F7 are as described in the test examples described later.

[0097] (2) Increase in adhesion In the workpiece processing sheet of the present embodiment, the adhesion force increase amount (F7-F0) calculated by subtracting the adhesion force F0 from the adhesion force F7 is preferably 500mN / 25mm or less, particularly preferably 100mN / 25mm or less, and further preferably 50mN / 25mm or less. Thus, even after long-term storage in a state of being attached to the active surface of the workpiece, it is easy to separate the workpiece. In addition, the lower limit of the adhesion force increase amount (F7-F0) is not particularly limited, for example, preferably 10mN / 25mm or more.

[0098] (3) Adhesion In the workpiece processing sheet of the present embodiment, the above-mentioned adhesion F0 is preferably 20mN / 25mm or more, particularly preferably 30mN / 25mm or more, and more preferably 40mN / 25mm or more. In addition, the above-mentioned adhesion F0 is preferably 1200mN / 25mm or less, particularly preferably 600mN / 25mm or less, and more preferably 400mN / 25mm or less. By being the above-mentioned range, it is easy to meet the above-mentioned adhesion increase rate or adhesion increase amount.

[0099] In addition, in the workpiece processing sheet of the present embodiment, the above-mentioned adhesion F7 is preferably 20mN / 25mm or more, particularly preferably 30mN / 25mm or more, and further preferably 40mN / 25mm or more. In addition, the above-mentioned adhesion F7 is preferably 1200mN / 25mm or less, particularly preferably 600mN / 25mm or less, and further preferably 400mN / 25mm or less. By being in the above range, it is easy to meet the above-mentioned adhesion increase rate or adhesion increase amount.

[0100] 5. Method for manufacturing sheet for workpiece processing The method for producing the workpiece processing sheet of the present embodiment is not particularly limited, but it is preferably produced by laminating an adhesive layer on one side of a substrate.

[0101] The adhesive layer can be stacked on the single side of the substrate using a known method. For example, the adhesive layer formed on the release sheet is preferably transferred to the single side of the substrate. At this time, an adhesive composition containing an adhesive layer and a coating liquid containing a solvent or a dispersion medium as required is prepared, and a die coater, a curtain coater, a spray coater, a slit coater, a blade coater, a roller knife coater, an applicator, etc. are used to apply the coating liquid on the peeling-treated surface of the release sheet (hereinafter, sometimes referred to as "peeling surface") to form a coating film, and the coating film is dried, thereby forming an adhesive layer. As long as it can be coated, the properties of the coating liquid are not particularly limited. If there is sometimes a component containing a solute for forming an adhesive layer, there is sometimes a component containing a dispersed substance for forming an adhesive layer. The release sheet of the laminate can be peeled off as a process material, and can also be used to protect the adhesive surface of the adhesive layer during the period before the workpiece processing sheet is attached to the adherend.

[0102] When the coating liquid for forming the adhesive layer contains a crosslinking agent, the active energy ray-curable polymer (A) in the coating film and the crosslinking agent are crosslinked by changing the above-mentioned drying conditions (temperature, time, etc.) or by providing a heat treatment, so that a crosslinked structure is formed in the adhesive layer at a desired density. In order to fully carry out the crosslinking reaction, the following aging can be carried out: after laminating the adhesive layer on the substrate using the above-mentioned method, for example, the obtained workpiece processing sheet is left to stand for several days under an environment of 23° C. and a relative humidity of 50%.

[0103] The adhesive layer may be directly formed on the substrate instead of transferring the adhesive layer formed on the release sheet in the above manner to one side of the substrate. In this case, the adhesive layer is formed by applying a coating liquid for forming the above adhesive layer on one side of the substrate to form a coating film, and drying the coating film.

[0104] 6. How to use the workpiece processing sheet The workpiece processing sheet of the present embodiment can be used for processing a workpiece. That is, after the adhesive surface of the workpiece processing sheet of the present embodiment is attached to one side of the workpiece, the workpiece can be processed on the workpiece processing sheet. Examples of such processing include back grinding, cutting, expansion, picking up, etc. The above-mentioned cutting can be, for example, cutting with a rotating circular blade, laser cutting in which a semiconductor wafer is fully cut by irradiating a laser, or stealth cutting in which a modified layer is formed on the semiconductor wafer by irradiating a laser, and then the semiconductor wafer is stretched to separate the semiconductor wafer at the modified layer. The workpiece processing sheet of the present embodiment can be used as a back grinding sheet, a cutting sheet, an expansion sheet, a picking sheet, etc., depending on the type of processing.

[0105] As examples of workpieces processed using the workpiece processing sheet of the present embodiment, semiconductor components such as semiconductor wafers and semiconductor packages; glass components such as glass plates can be cited. Wherein, as described above, even when the adhesive sheet is attached to the active surface of a workpiece having an active surface, the workpiece processing sheet of the present embodiment can still well suppress the increase in the adhesion of the workpiece processing sheet to the active surface. Therefore, the workpiece processing sheet of the present embodiment is suitable for processing a workpiece having an active surface (especially the ground surface of a semiconductor wafer within 120 minutes from the grinding surface). However, the workpiece processing sheet of the present embodiment can be attached to any one of a workpiece having an active surface (especially the ground surface of a semiconductor wafer within 120 minutes from the grinding surface), and a common workpiece without an active surface (especially the surface other than the ground surface of a semiconductor wafer within 120 minutes from the grinding surface).

[0106] When the workpiece is processed on the workpiece processing sheet of the present embodiment and the processed workpiece is separated from the workpiece processing sheet, it is preferred that the adhesive layer of the workpiece processing sheet is irradiated with active energy rays before the separation. Thus, the adhesive layer is cured, the adhesion of the workpiece processing sheet to the processed workpiece is well reduced, and the separation of the processed workpiece becomes easy.

[0107] As the above-mentioned active energy ray, for example, active energy ray having energy quantum in electromagnetic wave or charged particle beam can be used, specifically, ultraviolet ray or electron beam can be used. Ultraviolet ray which is easy to operate is particularly preferred. Ultraviolet ray irradiation can be carried out using a high pressure mercury lamp, a xenon lamp, an LED, etc., and the irradiation intensity of ultraviolet ray is preferably 1 mW / cm 2 Above and 1000mW / cm 2 In addition, the light intensity is preferably 10 mJ / cm 2 Above, particularly preferably 80 mJ / cm 2 More preferably, 150 mJ / cm 2 In addition, the light intensity is preferably 10000 mJ / cm 2 Below, particularly preferably 5000 mJ / cm 2 Below, more preferably 2000mJ / cm 2 On the other hand, the irradiation with electron beams can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably 10 krad or more and 1000 krad or less.

[0108] The workpiece processing sheet of this embodiment is particularly preferably used in a method for manufacturing a processed workpiece having the following steps. That is, the method for manufacturing a processed workpiece has the following steps: a grinding step of grinding the surface of the workpiece; a step of attaching the workpiece processing sheet of this embodiment to the ground surface of the workpiece; a step of cutting the workpiece on the workpiece processing sheet to obtain chips obtained by singulating the workpiece; an active energy ray irradiation step of irradiating the adhesive layer of the workpiece processing sheet with active energy rays; and a step of picking up the chips one by one from the workpiece processing sheet.

[0109] The above-mentioned grinding process can be carried out using a conventionally known method. For example, the adhesive surface of the desired adhesive sheet (which can be a workpiece processing sheet of the present embodiment) is attached to one face of the workpiece, and a grinding device is used to grind the other face of the workpiece on the above-mentioned adhesive sheet. The degree of grinding at this time can be selected according to the purpose, for example, grinding to the thickness of the workpiece or the state of the surface reaches a prescribed degree. After the grinding, the surface that has been ground can be subjected to conventionally known surface treatment.

[0110] In the subsequent attaching process, as long as the adhesive surface of the workpiece processing sheet of this embodiment is attached to the grinding surface of the workpiece, the specific method is not limited. Among them, the time from grinding the surface of the workpiece in the above-mentioned grinding process to the above-mentioned attachment can be within 120 minutes, especially within 30 minutes, and further within 5 minutes. When the above-mentioned time is within 120 minutes, although the grinding surface of the workpiece is an active surface that maintains an activated state, according to the workpiece processing sheet of this embodiment, even for such an active surface, the excessive increase of adhesion can be suppressed, and it can also be picked up well in the picking-up process described later.

[0111] The subsequent cutting process can be performed using a conventionally known method. That is, a cutting device is used to cut the workpiece on the workpiece processing sheet to obtain a plurality of chips formed by singulating the workpiece. The type of cutting is not particularly limited, and can be, for example, blade cutting, laser cutting, stealth cutting, etc.

[0112] The irradiation with active energy rays in the active energy ray irradiation step can be performed by a conventionally known method. The type of active energy rays and the irradiation conditions are as described above.

[0113] The picking up in the subsequent picking up process can also be performed using a conventionally known method. For example, the picking up can be performed by using a picking up device to expand the workpiece processing sheet, using a striker to lift the semiconductor chip from the back of the workpiece processing sheet, and further using a suction nozzle to remove the chip. The workpiece processing sheet according to this embodiment can suppress the excessive increase in the adhesion between the workpiece and the chip, thereby avoiding the problem of being unable to pick up the chip and being able to pick up well.

[0114] The embodiments described above are described for easy understanding of the present invention and are not intended to limit the present invention. Therefore, each element disclosed in the above embodiments includes all design changes or equivalents within the technical scope of the present invention.

[0115] For example, another layer may be provided between the substrate and the adhesive layer, or on the surface of the substrate opposite to the adhesive layer. Example

[0116] Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[0117] [Example 1] (1) Preparation of substrate Ethylene-methacrylic acid copolymer (EMAA) (manufactured by DOW-MITSUI POLYCHEMICALS CO., LTD., product name "NUCREL N0903HC") was extruded using a small T-die extruder (manufactured by Toyo Seiki Seisaku-sho, Ltd., product name "LaboPlastomill") to obtain an EMAA film with a thickness of 80 μm. In addition, both sides of the obtained EMAA film were corona treated. Thus, a substrate was obtained.

[0118] (2) Preparation of adhesive composition 40 parts by mass of 2-ethylhexyl acrylate, 40 parts by mass of vinyl acetate and 20 parts by mass of 2-hydroxyethyl acrylate were polymerized by solution polymerization to obtain a (meth)acrylate polymer. The weight average molecular weight of the (meth)acrylate polymer was measured by the method described below and was 650,000.

[0119] The obtained (meth)acrylate polymer was reacted with methacryloyloxyethyl isocyanate (MOI) in an amount corresponding to 80 mol% relative to 2-hydroxyethyl acrylate constituting the (meth)acrylate polymer to obtain an acrylic polymer (active energy ray curable polymer) having an active energy ray curable group introduced into the side chain. The weight average molecular weight (Mw) of the active energy ray curable polymer was measured by the method described below and the result was 700,000.

[0120] 100 parts by mass of the obtained active energy ray-curable polymer, 1 part by mass of trimethylolpropane-modified toluene diisocyanate (manufactured by Mitsui Chemicals, Inc., product name: "TAKENATE D-101E") as a crosslinking agent, and 3 parts by mass of 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2- Methyl-propane-1-one (manufactured by IGM Resins, product name "Omnirad 127") and 1.1 parts by mass of 1,2,3,4-butanetetracarboxylic acid tetrakis(2,2,6,6-tetramethyl-4-piperidyl) ester (N-methyl hindered amine stabilizer, manufactured by ADEKA CORPORATION, product name "ADK STAB LA-52") as a stabilizer were added to obtain a coating liquid of an adhesive composition (solid content concentration: 30% by mass).

[0121] (3) Formation of Adhesive Layer The coating liquid of the adhesive composition obtained in the above step (2) is applied to the release surface of a release sheet (manufactured by LINTEC Corporation, product name "SP-PET381031") having a silicone release layer formed on one side of a polyethylene terephthalate film having a thickness of 38 μm, and the film is dried by heating to obtain a laminate having an adhesive layer having a thickness of 5 μm formed on the release sheet.

[0122] (4) Preparation of adhesive sheet One surface of the substrate obtained in the step (1) was bonded to the adhesive layer side surface of the laminate obtained in the step (3), and then stored in a light-shielded state at 23° C. and 50% environment for 10 days. Thus, a workpiece processing sheet was obtained.

[0123] (5) Determination of weight average molecular weight (Mw) of (meth)acrylate copolymer The weight average molecular weight (Mw) of the (meth)acrylate copolymer is a polystyrene-equivalent weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC). <Measurement conditions> ·GPC measuring apparatus: manufactured by TOSOH CORPORATION, HLC-8320 ·GPC column (passed in the following order): TSK gel Super HH manufactured by TOSOH CORPORATION TSK gel Super HM-H TSK gel Super H2000 ·Test solvent: tetrahydrofuran ·Measurement temperature: 40℃

[0124] [Examples 2 to 4 and Comparative Examples 2 to 4] Except having changed the kind and content of the stabilizer as shown in Table 1, the same method as Example 1 was carried out to obtain a workpiece processing sheet.

[0125] [Example 5] A workpiece processing sheet was obtained in the same manner as in Example 1 except that the composition of the acrylic polymer (active energy ray curable polymer), the content of the crosslinking agent, and the type and content of the stabilizer were changed as shown in Table 1. The weight average molecular weight (Mw) of the acrylic polymer (active energy ray curable polymer) obtained in Example 5 was measured by the above-mentioned method and was 800,000.

[0126] [Example 6] 68.5 parts by mass of n-butyl acrylate, 30 parts by mass of methyl acrylate, 0.5 parts by mass of 2-hydroxyethyl acrylate and 1 part by mass of acrylamide were polymerized by solution polymerization to obtain an acrylic polymer. The weight average molecular weight of the acrylic polymer was measured by the method described below and was 1,000,000.

[0127] 100 parts by mass of the obtained acrylic polymer, 120 parts by mass of a pentaerythritol-based 5-9 functional urethane acrylate oligomer having an active energy ray-curable group and a weight average molecular weight of 2300, 8 parts by mass of trimethylolpropane-modified toluene diisocyanate (produced by Mitsui Chemicals, Inc., product name “TAKENATE D-101E”) as a crosslinking agent, and 6 parts by mass of 1-hydroxycyclohexyl phenyl ketone (produced by IGM Resins, product name “Omnirad”) as a photopolymerization initiator were mixed in a solvent. 184”), 2.0 parts by mass of a mixed ester of 1,2,3,4-butanetetracarboxylic acid, 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 a stabilizer (N-methyl hindered amine stabilizer, manufactured by ADEKA CORPORATION, product name “ADK STAB LA-63P”), to obtain a coating liquid of the adhesive composition (solid content concentration is 30% by mass).

[0128] A workpiece processing sheet was obtained in the same manner as in Example 1 except that the coating liquid of the above-mentioned adhesive composition was used.

[0129] [Comparative Example 1] A workpiece processing sheet was obtained in the same manner as in Example 1 except that no stabilizer was used.

[0130] [Comparative Example 5] A workpiece processing sheet was obtained in the same manner as in Example 6 except that no stabilizer was used.

[0131] [Test Example 1] (Measurement of Adhesion to Active Surface) The workpiece processing sheet manufactured in the embodiment and the comparative example is cut into strips with a width of 25 mm. On the other hand, a single side of the silicon wafer is ground using a grinding device (manufactured by DISCO CORPORATION, product name "DFG8540") until the thickness of the silicon wafer is 500 μm. Under an environment of a temperature of 23°C and a relative humidity of 50%, a 2 kg rubber roller is used to attach the exposed surface of the adhesive layer exposed by peeling off the peeling sheet from the above-mentioned strip-shaped workpiece processing sheet to the grinding surface (active surface) activated by grinding, and then let it stand for 20 minutes to prepare a sample for measurement. In addition, the attachment of the workpiece processing sheet to the above-mentioned active surface is carried out within 5 minutes from the start of the above-mentioned grinding.

[0132] The measurement sample was stored in an environment with a temperature of 23° C. and a relative humidity of 50%. The storage period at this time was 1 hour.

[0133] After storage, the samples were irradiated with ultraviolet light (manufactured by LINTEC Corporation, product name "RAD-2010"), and irradiate the adhesive layer with ultraviolet light (UV) through the substrate (illuminance: 230 mW / cm 2 , light intensity: 190mJ / cm 2 ) to cure the adhesive layer.

[0134] Next, a universal tensile tester (manufactured by ORIENTEC CORPORATION, product name "TENSILONUTM-4-100") was used to peel the workpiece processing sheet 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 a 180° peeling method based on JIS Z 0237:2009. The adhesive force thus obtained was defined as the adhesive force at storage day 0 (F0) and is shown in Table 1.

[0135] In addition, the adhesive strength of the sample whose storage period was changed to 7 days (about 168 hours) was measured in the same manner as above. The results are shown in Table 1 as the adhesive strength after storage for 7 days (F7).

[0136] Then, the adhesive force (F0) was subtracted from the adhesive force (F7) measured as described above to calculate the increase in adhesive force (mN / 25 mm) 7 days after the start of application.

[0137] Furthermore, the adhesive force increase rate 7 days after the application was calculated as the ratio (F7 / F0) of the adhesive force (F7) measured as described above to the adhesive force (F0).

[0138] [Test Example 2] (Evaluation of Pickup Properties) A single side of the silicon wafer was ground using a grinding device (manufactured by DISCO CORPORATION, product name "DFG8540") until the thickness of the silicon wafer was 150 μm. Using a laminating device, the adhesive surface of the adhesive layer exposed by peeling off the peeling sheet from the workpiece processing sheet manufactured in the embodiment and the comparative example was attached to the grinding surface (active surface) activated by the grinding. In addition, the attachment was performed within 5 minutes from the start of the above grinding.

[0139] After the above-mentioned attachment, the film was stored in an environment of a temperature of 23° C. and a relative humidity of 50% for 7 days, and then cut under the following conditions. <Cutting conditions> Cutting device: DFD-6362 manufactured by DISCO CORPORATION Blade: NBC-2H 2050 27HECC manufactured by DISCO CORPORATION Blade width: 0.025~0.030mm · Tool tip feed: 0.640~0.760mm Blade speed: 35000rpm Cutting speed: 60 mm / s ·Substrate cutting depth: 20μm Cutting water volume: 1.0L / min Cutting water temperature: 20℃ Cutting size: 2.0mm square

[0140] Furthermore, an ultraviolet irradiation device (manufactured by LINTEC Corporation, product name "RAD-2010"), irradiate the adhesive layer of the workpiece processing sheet with ultraviolet light (UV) through the substrate (illuminance: 230 mW / cm 2 , light intensity: 190mJ / cm 2 ) to cure the adhesive layer.

[0141] Next, among the multiple chips obtained by the above-mentioned cutting, a pick-up device is used to try to pick up a chip located near the center when looking down at the workpiece processing sheet. Specifically, a striker is used to lift the chip from the surface on the substrate side of the workpiece processing sheet at a lifting height of 500 μm, and a vacuum suction nozzle is used to adsorb the surface of the chip on the opposite side of the workpiece processing sheet, thereby trying to separate the chip from the workpiece processing sheet. Whether the chip can be separated at this time, the pick-up property is evaluated according to the following standards. The results are shown in Table 1 as the pick-up property of the active wafer. ○: Chip can be separated ×: The chip cannot be separated.

[0142] In addition, the details of the abbreviations and the like described in Table 1 are as follows. [monomer] 2EHA: 2-Ethylhexyl acrylate VAc: Vinyl acetate HEA: 2-Hydroxyethyl Acrylate ACMΟ: Acryloylmorpholine BA: n-butyl acrylate MA: Methyl acrylate AAm: Acrylamide [Oligomer having an active energy ray-curable group] 5-9 functional acrylate: 5-9 functional urethane acrylate oligomer of pentaerythritol with a weight average molecular weight of 2300 [Photopolymerization initiator] Omnirad 127: 2-Hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl}-2-methyl-propane-1-one (manufactured by IGM Resins, product name "Omnirad 127") Omnirad 184: 1-Hydroxycyclohexylphenyl ketone (manufactured by IGM Resins, product name "Omnirad 184") [Stabilizer] LA-52: 1,2,3,4-Butanetetracarboxylic acid tetrakis (2,2,6,6-tetramethyl-4-piperidinyl) ester (N-methyl hindered amine stabilizer, manufactured by ADEKA CORPORATION, product name "ADK STAB LA-52") LA-63P: A mixed ester of 1,2,3,4-butanetetracarboxylic acid, 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 hindered amine stabilizer, manufactured by ADEKA CORPORATION, product name "ADK STAB LA-63P") AO-50: Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate (hindered phenol stabilizer, manufactured by ADEKA CORPORATION, product name "ADK STAB AO-50") AO-60: Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (hindered phenol stabilizer, manufactured by ADEKA CORPORATION, product name "ADK STAB AO-60") 2112: Tris(2,4-di-tert-butylphenyl) phosphite (phosphite stabilizer, manufactured by ADEKA CORPORATION, product name "ADK STAB 2112")

[0143]

[0144] As can be seen from Table 1, the workpiece processing sheet of the example can exhibit excellent pickup properties even when stored for a long period of time (storage for 7 days) after being attached to the active surface of the silicon wafer. Industrial Applicability

[0145] The workpiece processing sheet of the present invention is suitable for use as a cutting sheet or the like for a workpiece having an active surface.

Claims

1. A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, wherein the workpiece processing sheet is characterized in that: The adhesive layer is composed of an active energy ray-curable adhesive containing a hindered amine stabilizer. The workpiece processing sheet is used to be attached to the polished surface of the workpiece within 120 minutes from the start of polishing.

2. A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, wherein the workpiece processing sheet is characterized in that: The adhesive layer is composed of an active energy ray-curable adhesive containing a hindered amine stabilizer. A laminate of the workpiece processing sheet and the silicon wafer obtained by attaching the surface of the adhesive layer opposite to the substrate to the polished surface of the silicon wafer within 20 minutes from the start of polishing the surface, The adhesive force of the workpiece processing sheet to the silicon wafer after the adhesive layer is irradiated with ultraviolet rays immediately after the attachment is defined as F0, When the adhesive force of the workpiece processing sheet to the silicon wafer after irradiating the adhesive layer with ultraviolet rays 7 days after the attachment is defined as F7, The adhesive force increase rate calculated as the ratio of the F7 to the F0 (F7 / F0) is 2.0 or less.

3. The workpiece processing sheet according to claim 1 or 2, characterized in that: The hindered amine stabilizer is an N-alkyl hindered amine stabilizer.

4. The workpiece processing sheet according to claim 1 or 2, characterized in that: The active energy ray-curable adhesive is formed of an adhesive composition containing an acrylic polymer having an active energy ray-curable group introduced into a side chain and the hindered amine stabilizer.

5. A method for manufacturing a processed workpiece, characterized in that: The manufacturing method comprises: A grinding process in which the surface of a workpiece is ground; a step of attaching the workpiece processing sheet according to claim 1 or 2 to the polished surface of the workpiece; A dicing step of dicing the workpiece on the workpiece processing sheet to obtain a plurality of chips obtained by singulating the workpiece; an active energy ray irradiation step of irradiating the adhesive layer of the workpiece processing sheet with active energy rays; and A picking up step of picking up the chips one by one from the workpiece processing sheet.

6. The method for manufacturing a processed workpiece according to claim 5, characterized in that: The step of attaching the workpiece processing sheet to the workpiece is performed within 120 minutes from the start of grinding the surface of the workpiece in the grinding step.

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