Workpiece processing sheet and method for manufacturing semiconductor device

Abstract

The present invention relates to 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, the active energy ray-curable adhesive being formed of an adhesive composition containing at least an acrylic polymer and a tackifier, wherein the tackifier is an alkylene glycol-modified rosin ester. According to the workpiece processing sheet, even with respect to the active surface of the workpiece, excessive increase in adhesion can be suppressed, and good workpiece processing can be achieved.

Description

Technical Field

[0001] The present invention relates to a workpiece processing sheet that can be suitably used for processing workpieces such as semiconductor wafers, and in particular to a workpiece processing sheet that can be suitably used for processing a workpiece having a surface in an active state (hereinafter sometimes referred to as an "active surface"). Background Art

[0002] Semiconductor wafers such as silicon and gallium arsenide and various packages are manufactured in a large diameter state, cut (diced) into small component pieces (semiconductor chips), peeled (picked up), and then transferred to the mounting process as a subsequent 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, expanding (expanding), picking up, mounting 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 to singulate it into multiple chips. Then, in the picking process, the multiple chips obtained are picked up from the workpiece processing sheet.

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

[0005] In recent years, the above-mentioned grinding, replacement attachment and cutting processes are sometimes performed online continuously. At this time, the workpiece processing sheet is attached to the grinding surface of the workpiece just after grinding.

[0006] Here, the grinding surface of the workpiece just after grinding is usually in an activated state by grinding. Therefore, when the workpiece processing sheet is attached after the workpiece is just ground, the workpiece processing sheet is attached to the active surface of the workpiece. At this time, since the active surface is active, the adhesion between the workpiece and the workpiece processing sheet is prone to excessive increase. In particular, the longer the time of the stacking state of the workpiece and the workpiece processing sheet is, the more the adhesion tends to increase. And, in the case where the workpiece and the workpiece processing sheet are overly close to each other like this, in the subsequent picking process, since the obtained chip becomes firmly close to the workpiece processing sheet, it is impossible to pick up well.

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

[0008] In order to solve the problem of increased adhesion to the active surface of the workpiece as described above, Patent Document 1 discloses a dicing adhesive tape or sheet having a radiation-curable adhesive layer containing polyalkylene glycols or derivatives thereof.

[0009] Prior art literature

[0010] Patent Literature

[0011] Patent Document 1: Japanese Patent Application Publication No. 2008-060434 Summary of the invention

[0012] Technical Problems to be Solved by the Invention

[0013] However, even when the workpiece processing sheet disclosed in Patent Document 1 is used, it is not possible to suppress an excessive increase in the adhesion of the workpiece processing sheet to the active surface of the workpiece, and it is difficult to achieve good workpiece processing.

[0014] The present invention is completed in view of such actual conditions, and its purpose is to provide a workpiece processing sheet and a method for manufacturing a semiconductor device using the workpiece processing sheet, wherein the workpiece processing sheet can suppress excessive increase in adhesion even with respect to the active surface of the workpiece and can achieve good workpiece processing.

[0015] Technical means to solve technical problems

[0016] In order to achieve the above-mentioned purpose, first, the present invention provides a workpiece processing sheet, which comprises 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, and the active energy ray-curable adhesive is formed by an adhesive composition containing at least an acrylic polymer and a tackifier, and the tackifier is an alkylene glycol-modified rosin ester (Invention 1).

[0017] In the workpiece processing sheet of the above invention (Invention 1), the adhesive layer is composed of the following active energy ray-curable adhesive, and even when a workpiece having an active surface is used as the workpiece, the excessive increase in adhesion to the active surface can be suppressed. As a result, the processed workpiece (chip, etc.) can be well separated from the workpiece processing sheet, and as a result, good workpiece processing can be achieved.

[0018] In the above invention (Invention 1), the content of the tackifier in the adhesive composition is 0.005 parts by mass or more, and preferably 15 parts by mass or less, relative to 100 parts by mass of the acrylic polymer (Invention 2).

[0019] In the above inventions (Inventions 1 and 2), it is preferred that the tackifier has a softening point of -100°C to 50°C (Invention 3).

[0020] In the above inventions (Inventions 1 to 3), it is preferred that the weight average molecular weight of the tackifier is 1,000 or more (Invention 4).

[0021] In the above inventions (Inventions 1 to 4), it is preferred that the adhesive force of the workpiece processing sheet to the mirror surface of the silicon wafer before irradiating the workpiece processing sheet with active energy rays is 200 mN / 25 mm to 20000 mN / 25 mm (Invention 5).

[0022] In the above inventions (Inventions 1 to 5), it is preferred that the acrylic polymer has active energy ray-curable properties (Invention 6).

[0023] In the above inventions (Inventions 1 to 6), it is preferred that the acrylic polymer contains 10% by mass or more of a monomer whose homopolymer has a glass transition temperature Tg of -30°C or less, and at the same time contains 3% by mass or more of a monomer whose homopolymer has a glass transition temperature Tg of 10°C or more as a monomer unit constituting the acrylic polymer (Invention 7).

[0024] In the above invention (Invention 7), the monomer having a homopolymer glass transition temperature Tg of 10°C or higher is at least one monomer selected from methyl acrylate, methyl methacrylate, acryloylmorpholine, vinyl acetate and 2-hydroxyethyl methacrylate (Invention 8).

[0025] In the above inventions (Inventions 1 to 8), it is preferred that the workpiece processing sheet be attached to the polished surface of the semiconductor wafer within 120 minutes after the surface is polished (Invention 9).

[0026] In the above inventions (Inventions 1 to 9), it is preferred that the workpiece processing sheet can be attached to both the polished surface and surfaces other than the polished surface of the semiconductor wafer within 120 minutes after the surface is polished (Invention 10).

[0027] Second, the present invention provides a method for manufacturing a semiconductor device, characterized in that it comprises: a grinding step for grinding the surface of a semiconductor wafer; an attaching step for attaching the workpiece processing sheet (Inventions 1 to 10) to the grinded surface of the semiconductor wafer; a cutting step for cutting the semiconductor wafer on the workpiece processing sheet to obtain a plurality of semiconductor chips; an active energy ray irradiation step for irradiating the adhesive layer in the workpiece processing sheet with active energy rays; and a picking up step for picking up each of the semiconductor chips from the workpiece processing sheet (Invention 11).

[0028] In the above invention (Invention 11), it is preferred that the workpiece processing sheet be attached to the semiconductor wafer in the attaching step within 120 minutes after the surface of the semiconductor wafer is polished in the polishing step (Invention 12).

[0029] Effects of the Invention

[0030] 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, according to the manufacturing method of the present invention, a semiconductor device can be manufactured well. DETAILED DESCRIPTION

[0031] Hereinafter, embodiments of the present invention will be described.

[0032] A workpiece processing sheet according to one embodiment of the present invention comprises 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, and the active energy ray-curable adhesive is formed of an adhesive composition containing at least an acrylic polymer and a tackifier. Furthermore, the tackifier is an alkylene glycol-modified rosin ester.

[0033] As described above, the workpiece processing sheet of the present embodiment is formed of an adhesive layer made of an active energy ray-curable adhesive, which is formed of an adhesive composition containing a tackifier that is an alkylene glycol-modified rosin ester, so that even when the adhesive surface is attached to the active surface of the workpiece, the adhesion to the active surface can be suppressed from excessively increasing. Thus, the processed workpiece can be well separated from the workpiece processing sheet, and as a result, good workpiece processing can be performed by using the workpiece processing sheet of the present embodiment.

[0034] As the reason for the excessive increase of the adhesion as mentioned above, although not limited to this, it is speculated as follows. It is believed that first, as a mechanism for the activation of the workpiece surface, the inactive part present on the surface is removed by grinding the surface of the workpiece, so that the active part inside is exposed. For example, when the workpiece is a silicon wafer, it is believed that the surface of the silicon wafer is oxidized under normal conditions to form an inactive SiO2 film. If the surface of such a silicon wafer is ground, the SiO2 film is removed and the silicon atoms in the unoxidized state are exposed. In addition, the exposed silicon atoms react with the cleaning water used in the back grinding process or the moisture in the atmosphere to partially form a structure of Si-H or Si-OH. In this way, the surface exposed by removing the SiO2 film is easy to interact with the adhesive surface of the ordinary workpiece processing sheet, and becomes a state that is easy to produce chemical bonds with the adhesive constituting the adhesive layer.

[0035] In addition, in this specification, the state in which the surface of the workpiece has been activated refers to the state in which the SiO2 film has been removed from its surface, and particularly refers to the state within 120 minutes after the surface of the workpiece has been ground, preferably refers to the state within 30 minutes after the surface of the workpiece has been ground, and more preferably refers to the state within 5 minutes after the surface of the workpiece has been ground.

[0036] Next, as a mechanism by which the workpiece processing sheet of the present embodiment can suppress excessive increase in adhesion even for the active surface of the workpiece produced in the above manner, it is considered as follows. The adhesive layer of the present embodiment is usually formed by using the above-mentioned adhesive composition to form a coating film, and the coating film is solidified and formed. Here, the molecular weight of the alkylene glycol-modified rosin ester contained in the adhesive composition is relatively large, and the compatibility with other components contained in the adhesive composition is relatively low. In addition, the alkylene glycol-modified rosin ester has a high fluidity at room temperature and is easy to move in the adhesive composition. In this way, the low compatibility between the alkylene glycol-modified rosin ester and other components and the easy movement in the adhesive composition complement each other, and in the coating film formed using the adhesive composition, the alkylene glycol-modified rosin ester is easy to move to its surface. By curing such a coating film, an adhesive layer is formed in which the alkylene glycol-modified rosin ester is preferentially present near the surface, and as a result, the workpiece processing sheet of the present embodiment becomes a workpiece processing sheet in which the alkylene glycol-modified rosin ester is preferentially present near its adhesive surface. In addition, it is believed that the alkylene glycol-modified rosin ester present near the adhesive surface acts in a manner that suppresses interaction or chemical bonding with the active surface of the workpiece as described above, thereby suppressing excessive increase in the adhesion between the active surface of the workpiece and the workpiece processing sheet of the present embodiment.

[0037] 1. Constituent components of workpiece processing sheets

[0038] (1) Base material

[0039] As the substrate of the present embodiment, as long as the function required when using the workpiece processing sheet can be exerted, it is not particularly limited. In particular, the substrate is preferably a resin film with a resin material as the main material. As its specific example, polyolefin films such as polyethylene film, polypropylene film, polybutylene film, polybutadiene film, polymethylpentene film, ethylene-norbornene copolymer film, and norbornene resin film can be listed; polyester films such as polyethylene terephthalate film, polybutylene terephthalate film, and polyethylene naphthalate; ethylene-vinyl acetate copolymer film; ethylene-(methyl) acrylic acid copolymer film, ethylene-(methyl) methyl acrylate copolymer film, and other ethylene-(methyl) acrylic acid ester copolymer films and other ethylene copolymer films; polyvinyl chloride films such as polyvinyl chloride film and vinyl chloride copolymer film; (methyl) acrylic acid ester copolymer film; polyurethane film; polyimide film; polystyrene film; polycarbonate film; fluororesin film, etc. In addition, modified films such as cross-linked films and ionomer films of the above-mentioned films can also be used. In addition, the substrate can also be a laminated film formed by stacking a plurality of the above-mentioned films. In this laminated film, the material constituting each layer can be the same type or different types. Among the above, it is preferred to use ethylene copolymer films, and it is particularly preferred to use ethylene-(methyl) acrylic acid copolymer films. In addition, " (methyl) acrylic acid " in this specification refers to acrylic acid and methacrylic acid. Other similar terms are also the same. In addition, " polymer " in this specification also includes the concept of " copolymer ".

[0040] The substrate may also contain various additives such as flame retardants, plasticizers, antistatic agents, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, ion scavengers, etc. The content of these additives is not particularly limited, but is preferably set within a range in which the substrate can exert the desired function.

[0041] In order to improve the adhesion with the adhesive layer, the surface of the substrate on which the adhesive layer is to be 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, but is preferably 200 μm or less, particularly preferably 150 μm or less. The thickness of the substrate 11 is preferably 10 μm or more, particularly preferably 25 μm or more.

[0043] (2)Adhesive layer

[0044] The adhesive constituting the adhesive layer of this embodiment is not particularly limited as long as it is an active energy ray-curable adhesive formed from an adhesive composition containing at least an acrylic polymer and an alkylene glycol-modified rosin ester as a tackifier, and can achieve adhesion for processing a workpiece on the workpiece processing sheet.

[0045] The alkylene glycol-modified rosin ester is not particularly limited, but is preferably obtained by, for example, esterifying rosins, polyalkylene glycol monoalkyl ethers, polyhydric alcohols, and α,β-unsaturated carboxylic acids.

[0046] In addition, as the above-mentioned alkylene glycol-modified rosin ester, it is preferred to use an alkylene glycol-modified rosin ester having a softening point of 50°C or less, particularly preferably an alkylene glycol-modified rosin ester having a softening point of 20°C or less, and further preferably an alkylene glycol-modified rosin ester having a softening point of 0°C or less. By making the softening point 50°C or less, the fluidity of the alkylene glycol-modified rosin ester becomes higher, and as a result, the workpiece processing sheet of the present embodiment is easy to suppress excessive increase in adhesion to the active surface of the workpiece. In addition, the lower limit of the above-mentioned softening point is not particularly limited, but is preferably -100°C or more, particularly preferably -70°C or more, and further preferably -40°C or more.

[0047] In addition, as the above-mentioned alkylene glycol modified rosin ester, it is preferred to use an alkylene glycol modified rosin ester with a weight average molecular weight of more than 1000, particularly preferably to use an alkylene glycol modified rosin ester with a weight average molecular weight of more than 2000, and further preferably to use an alkylene glycol modified rosin ester with a weight average molecular weight of more than 3000. By making the weight average molecular weight more than 1000, it is easy to appropriately reduce the compatibility of other components in the alkylene glycol modified rosin ester and the adhesive composition, and as a result, the workpiece processing sheet of the present embodiment is easy to suppress the excessive rise of the adhesion to the active surface of the workpiece. In addition, from the perspective of compatibility with the adhesive composition, the upper limit of the above-mentioned weight average molecular weight is preferably less than 1,000,000, more preferably less than 100,000, particularly preferably less than 50,000, and further preferably less than 8000.

[0048] Relative to 100 parts by mass of acrylic polymer, the content of alkylene glycol modified rosin ester as a tackifier in the adhesive composition is preferably 0.005 parts by mass or more, particularly preferably 0.01 parts by mass or more, and further preferably 0.05 parts by mass or more. By making the above content 0.005 parts by mass or more, it is easy to effectively suppress the excessive rise of adhesion as described above. In addition, relative to 100 parts by mass of acrylic polymer, the above content is preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less, and further preferably 5 parts by mass or less. By making the above content 15 parts by mass or less, the workpiece processing sheet of the present embodiment is easy to have the required adhesion to the workpiece when processing the workpiece.

[0049] The adhesive constituting the adhesive layer of the present embodiment is an adhesive having active energy ray curing properties (hereinafter, sometimes referred to as "active energy ray curing adhesive"). By constituting the adhesive layer with active energy ray curing adhesive and curing the adhesive layer by irradiation with active energy rays, the adhesion of the workpiece processing sheet to the adherend can be reduced. As a result, the processed workpiece can be easily separated from the workpiece processing sheet.

[0050] The above-mentioned active energy ray-curable adhesive is not particularly limited as long as it is formed by an adhesive composition containing at least an acrylic polymer and a tackifier. For example, as the acrylic polymer, the above-mentioned adhesive composition may contain an acrylic polymer having active energy ray curability. Alternatively, the above-mentioned adhesive composition may also contain an acrylic polymer not having active energy ray curability and a monomer and / or oligomer having at least one active energy ray curable group.

[0051] First, the case where the active energy ray-curable adhesive is formed from an adhesive composition containing an acrylic polymer having active energy ray-curability will be described.

[0052] The acrylic polymer having active energy ray curability is preferably an acrylic polymer having an active energy ray curable functional group (active energy ray curable group) introduced into a side chain (hereinafter sometimes referred to as "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 functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group.

[0053] The functional group-containing monomer is preferably a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, carboxyl group, amino group, amide group, benzyl group, or glycidyl group in the molecule. Among the above, a monomer containing a hydroxyl group as a functional group (hydroxyl group-containing monomer) is preferably used.

[0054] As the hydroxyl-containing monomer, for example, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. can be listed, and among the above, 2-hydroxyethyl acrylate is preferably used. In addition, these hydroxyl-containing monomers can be used alone or in combination of two or more.

[0055] 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.

[0056] Examples of the amino group-containing monomer or amide group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. These amino group-containing monomers or amide group-containing monomers may be used alone or in combination of two or more.

[0057] The (meth)acrylate polymer (a1) preferably contains 3% by mass or more, particularly preferably 5% by mass or more, and further preferably 10% by mass or more of a structural unit derived from the above-mentioned functional group-containing monomer. In addition, the (meth)acrylate polymer (a1) preferably contains 40% by mass or less, particularly preferably 35% by mass or less, and further preferably 30% by mass or less of a structural unit derived from the above-mentioned functional group-containing monomer. By making the (meth)acrylate polymer (a1) contain the functional group-containing monomer in the above range, it is easy to form the desired active energy ray-curable polymer (A).

[0058] From the viewpoint of facilitating the formation of an adhesive having 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.

[0059] Specific examples of the alkyl (meth)acrylate 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, dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, octadecyl (meth)acrylate, etc. These alkyl (meth)acrylates may be used alone or in combination of two or more.

[0060] 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.

[0061] Examples of the other monomers include alkoxyalkyl-containing (meth)acrylates such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate; aliphatic ring-containing (meth)acrylates such as cyclohexyl (meth)acrylate; aromatic ring-containing (meth)acrylates such as phenyl (meth)acrylate; nitrogen-containing heterocyclic monomers such as N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, and N-(meth)acryloylpyrrolidone; non-crosslinking acrylamides such as (meth)acrylamide and N,N-dimethyl(meth)acrylamide; non-crosslinking tertiary amino group-containing (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; vinyl acetate; styrene, and the like.

[0062] In the workpiece processing sheet of the present embodiment, from the viewpoint of being able to exert the required adhesive force of the workpiece to be processed and being easy to further suppress the excessive increase of the adhesion to the active surface of the workpiece, the (meth)acrylate polymer (a1) preferably contains a monomer having a homopolymer glass transition temperature Tg of -30°C or less, and preferably further contains a monomer having a homopolymer glass transition temperature Tg of 10°C or more as a monomer unit constituting the (meth)acrylate polymer (a1). In particular, the (meth)acrylate polymer (a1) most preferably contains 10% by mass or more of a monomer having a homopolymer glass transition temperature Tg of -30°C or less, and at the same time contains 3% by mass or more of a monomer having a homopolymer glass transition temperature Tg of 10°C or more as a monomer unit constituting the (meth)acrylate polymer (a1).

[0063] As examples of the monomers having a glass transition temperature Tg of the homopolymer of -30°C or less, preferably n-butyl acrylate (Tg-55°C), 2-ethylhexyl acrylate (Tg-70°C), 2-methoxyethyl acrylate (Tg-50°C), n-octyl acrylate (Tg-65°C), isooctyl acrylate (Tg-58°C), isononyl acrylate (Tg-58°C), isodecyl acrylate (Tg-60°C), isodecyl methacrylate (Tg-41°C), n-dodecyl methacrylate (Tg-65°C), tridecyl acrylate (Tg-55°C), tridecyl methacrylate (Tg-40°C), ethoxydiethylene glycol acrylate (Tg-70°C), methoxytriethylene glycol acrylate (Tg-50°C), etc. These monomers may be used alone or in combination of two or more. Among the above, from the viewpoint of easily achieving the above effect, it is preferred to use at least one of n-butyl acrylate (Tg-55°C), 2-ethylhexyl acrylate (Tg-70°C) and 2-methoxyethyl acrylate (Tg-50°C).

[0064] When the (meth)acrylate polymer (a1) contains a monomer having a homopolymer glass transition temperature Tg of -30°C or less as a monomer unit constituting the (meth)acrylate polymer (a1), the content of the monomer is preferably 10% by mass or more, particularly preferably 20% by mass or more, and further preferably 30% by mass or more, from the perspective of facilitating the above-mentioned effect. In addition, the content of the above-mentioned monomer is preferably 90% by mass or less, particularly preferably 85% by mass or less, and further preferably 80% by mass or less.

[0065] Examples of monomers having a glass transition temperature Tg of 10°C or higher of the homopolymer include methyl acrylate (Tg 10°C), methyl methacrylate (Tg 105°C), acryloylmorpholine (Tg 145°C), vinyl acetate (Tg 28°C), 2-hydroxyethyl methacrylate (Tg 26°C), ethyl methacrylate (Tg 65°C), n-butyl methacrylate (Tg 20°C), isobutyl methacrylate (Tg 48°C), tert-butyl methacrylate (Tg 10 7°C), n-octadecyl acrylate (Tg30°C), n-octadecyl methacrylate (Tg38°C), cyclohexyl acrylate (Tg15°C), cyclohexyl methacrylate (Tg66°C), benzyl methacrylate (Tg54°C), isobornyl acrylate (Tg94°C), isobornyl methacrylate (Tg180°C), adamantyl acrylate (Tg115°C), tetrahydrofurfuryl methacrylate (Tg60°C), adamantyl methacrylate (Tg141°C), etc. These monomers may be used alone or in combination of two or more. Among the above, from the perspective of easiness in achieving the above effects, it is preferred to use at least one of methyl acrylate (Tg10°C), methyl methacrylate (Tg105°C), acryloylmorpholine (Tg145°C), vinyl acetate (Tg28°C) and 2-hydroxyethyl methacrylate (Tg26°C).

[0066] When the (meth)acrylate polymer (a1) contains a monomer having a homopolymer glass transition temperature Tg of 10°C or higher as a monomer unit constituting the (meth)acrylate polymer (a1), the content of the monomer is preferably 3% by mass or higher, particularly preferably 5% by mass or higher, and further preferably 10% by mass or higher from the viewpoint of facilitating the above-mentioned effect. In addition, the content of the above-mentioned monomer is preferably 60% by mass or lower, particularly preferably 50% by mass or lower, and further preferably 45% by mass or lower.

[0067] The polymerization method 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.

[0068] 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.

[0069] 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.

[0070] Furthermore, the unsaturated group-containing compound (a2) contains at least one, preferably 1 to 6, and more preferably 1 to 4 active energy ray-polymerizable carbon-carbon double bonds in one molecule. Specific examples of such unsaturated group-containing compounds (a2) include, for example, 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-(2-methacryloyloxyethoxy)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.

[0071] The unsaturated group-containing compound (a2) is preferably used in a ratio of 50 mol% or more, particularly preferably 60 mol% or more, and further preferably 70 mol% or more, relative to the molar number of the functional group-containing monomer in the (meth)acrylate polymer (a1). In addition, the unsaturated group-containing compound (a2) is preferably used in a ratio of 95 mol% or less, particularly preferably 93 mol% or less, and further preferably 90 mol% or less, relative to the molar number of the functional group-containing monomer in the (meth)acrylate polymer (a1).

[0072] 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).

[0073] The weight average molecular weight (Mw) of the active energy ray curable polymer (A) obtained in this way is preferably 100,000 or more, particularly preferably 150,000 or more, and more preferably 200,000 or more. In addition, the weight average molecular weight (Mw) is preferably 2 million or less, particularly preferably 1.5 million or less, and more preferably 1 million or less. In addition, the weight average molecular weight (Mw) in this specification is a value converted to standard polystyrene measured by gel permeation chromatography (GPC method).

[0074] Even when the active energy ray-curable adhesive is formed from an adhesive composition containing an active energy ray-curable acrylic polymer such as the active energy ray-curable polymer (A), the adhesive composition may further contain an active energy ray-curable monomer and / or oligomer (B).

[0075] As the active energy ray-curable monomer and / or oligomer (B), for example, esters of polyols and (meth)acrylic acid can be used.

[0076] Examples of the active energy ray-curable monomer and / or oligomer (B) include monofunctional acrylates such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; polyfunctional acrylates such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and dihydroxymethyltricyclodecane di(meth)acrylate; polyester oligo(meth)acrylate, polyurethane oligo(meth)acrylate, and the like.

[0077] When the adhesive composition of the present embodiment contains an active energy ray curable polymer (A) and an active energy ray curable monomer and / or oligomer (B), the content of the active energy ray curable monomer and / or oligomer (B) in the adhesive composition is preferably 5 parts by mass or more, particularly preferably 10 parts by mass or more, relative to 100 parts by mass of the active energy ray curable polymer (A). In addition, the content is preferably 150 parts by mass or less, particularly preferably 100 parts by mass or less, relative to 100 parts by mass of the active energy ray curable polymer (A).

[0078] Here, when ultraviolet rays are used as active energy rays for curing the active energy ray-curable adhesive, the adhesive composition preferably contains a photopolymerization initiator (C). By using a photopolymerization initiator (C), the polymerization curing time and the light irradiation amount can be reduced.

[0079] Specific examples of the photopolymerization initiator (C) 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 phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzil, dibenzil, diacetyl, β-chloroanthraquinone , (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, N,N-diethyldithiocarbamic acid-2-benzothiazolyl ester, oligo {2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]acetone}, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-1-{4-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methyl-propane-1-one, etc. Among the above, 2-hydroxy-1-{4-[4-[4-(2-hydroxy-2-methyl-propionyl)-benzyl]phenyl]-2-methyl-propane-1-one is preferably used. These photopolymerization initiators can be used alone or in combination of two or more.

[0080] The photopolymerization initiator (C) is preferably used in an amount of 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, relative to 100 parts by mass of the active energy ray-curable polymer (A) (when the active energy ray-curable monomer and / or oligomer (B) is blended, relative to 100 parts by mass of the total amount of the active energy ray-curable polymer (A) and the active energy ray-curable monomer and / or oligomer (B)). In addition, the photopolymerization initiator (C) is preferably used in an amount of 10 parts by mass or less, particularly preferably 6 parts by mass or less, relative to 100 parts by mass of the active energy ray-curable polymer (A) (when the active energy ray-curable monomer and / or oligomer (B) is blended, relative to 100 parts by mass of the total amount of the active energy ray-curable polymer (A) and the active energy ray-curable monomer and / or oligomer (B)).

[0081] In addition to the above components, the adhesive composition containing the active energy ray-curable acrylic polymer may also contain other components as appropriate, such as non-active energy ray-curable polymer components or oligomer components (D), crosslinking agents (E), and the like.

[0082] As the inactive energy ray curable polymer component or oligomer component (D), for example, polyacrylate, polyester, polyurethane, polycarbonate, polyolefin, etc. can be listed, preferably a polymer or oligomer with a weight average molecular weight (Mw) of 3000 to 2.5 million. By making the adhesive composition contain component (D), it is easy to improve the adhesion and peelability before curing, the strength after curing, the adhesion to other layers, the storage stability, etc. The blending amount of the component (D) is not particularly limited, and can be appropriately determined within the range of greater than 0 mass parts and less than 50 mass parts relative to 100 mass parts of the active energy ray curable polymer (A).

[0083] From the perspective of being easy to adjust the storage modulus of the adhesive layer 13 to the desired range, it is preferred to use a crosslinking agent (E). As a crosslinking agent (E), a polyfunctional compound reactive with the functional group possessed by the active energy ray curable polymer (A) etc. can be used. As examples of such polyfunctional compounds, isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, reactive phenolic resins etc. can be cited.

[0084] The amount of the crosslinking agent (E) added is preferably 0.01 parts by mass or more, particularly preferably 0.1 parts by mass or more, relative to 100 parts by mass of the active energy ray-curable polymer (A). In addition, the amount of the crosslinking agent (E) added is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, relative to 100 parts by mass of the active energy ray-curable polymer (A).

[0085] Next, the following describes a case where an active energy ray-curable adhesive is formed from an adhesive composition containing an acrylic polymer that does not have active energy ray curability (hereinafter sometimes referred to as a "non-active energy ray-curable acrylic polymer") and a monomer and / or oligomer having at least one active energy ray-curable group.

[0086] As the inactive energy ray-curable acrylic polymer, for example, the same components as those for the above-mentioned (meth)acrylate polymer (a1) can be used.

[0087] As a monomer and / or oligomer having at least one active energy ray curable group, the same component as the above-mentioned component (B) can be selected. Regarding the blending ratio of the non-active energy ray curable acrylic polymer and the monomer and / or oligomer having at least one active energy ray curable group, relative to 100 parts by mass of the non-active energy ray curable acrylic polymer, the monomer and / or oligomer having at least one active energy ray curable group is preferably 1 part by mass or more, and particularly preferably 50 parts by mass or more. In addition, regarding the blending ratio, relative to 100 parts by mass of the non-active energy ray curable acrylic polymer, the monomer and / or oligomer having at least one active energy ray curable group is preferably 200 parts by mass or less, and particularly preferably 160 parts by mass or less.

[0088] Even in this case, a photopolymerization initiator (C) and a crosslinking agent (E) may be appropriately blended in the same manner as described above.

[0089] The thickness of the adhesive layer is preferably 1 μm or more, particularly preferably 2 μm or more, and more preferably 3 μm or more. In addition, the thickness of the adhesive layer is preferably 100 μm or less, particularly preferably 50 μm or less, and more preferably 25 μm or less. By making the thickness of the adhesive layer within the above range, the workpiece processing sheet of the present embodiment can achieve sufficient adhesion to the workpiece that can be processed, and it is easy to suppress excessive increase in adhesion to the workpiece in an active state.

[0090] (3) Peel sheet

[0091] For the workpiece processing sheet of the present embodiment, a release sheet may be laminated on the surface for the purpose of protecting the surface until the adhesive surface is attached to the workpiece. The structure of the release sheet is arbitrary, and an example of a release sheet obtained by subjecting a plastic film to a release treatment using a release agent or the like can be shown. Specific examples of plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene. As release agents, silicones, fluorines, and long-chain alkyls can be used, among which silicones are preferred because they are cheap and can provide stable performance. The thickness of the release sheet is not particularly limited, but is generally not less than 20 μm and not more than 250 μm.

[0092] 2. Physical properties of workpiece processing sheets

[0093] For the workpiece processing sheet of the present embodiment, the adhesion of the workpiece processing sheet to the mirror surface of the silicon wafer before the workpiece processing sheet is irradiated with active energy rays is preferably 200mN / 25mm or more, particularly preferably 300mN / 25mm or more, and further preferably 400mN / 25mm or more. By making the above-mentioned adhesion force more than 200mN / 25mm, it is easy to fix the workpiece well on the adhesive surface of the workpiece processing sheet. As a result, the workpiece can be processed better, for example, when cutting, it is possible to effectively suppress chipping or chip scattering. In addition, the above-mentioned adhesion force is preferably less than 20000mN / 25mm, particularly preferably less than 10000mN / 25mm, and further preferably less than 5000mN / 25mm. By making the above-mentioned adhesion force less than 20000mN / 25mm, it is easy to suppress the excessive increase in the adhesion to the active surface of the workpiece. In addition, the mirror surface of the above-mentioned silicon wafer is not an active surface. The details of the method for measuring the adhesive force are as described in the test examples described later.

[0094] In addition, for the workpiece processing sheet of the present embodiment, after the adhesive surface of the workpiece processing sheet is attached to the mirror surface of the silicon wafer, the workpiece processing sheet is further irradiated with active energy rays, and the adhesion of the workpiece processing sheet to the mirror surface of the above-mentioned silicon wafer is preferably 200mN / 25mm or less, particularly preferably 100mN / 25mm or less, and more preferably 70mN / 25mm or less. By making the above-mentioned adhesion less than 200mN / 25mm, it is easy to separate the processed workpiece from the workpiece processing sheet well. In addition, the above-mentioned adhesion is preferably more than 10mN / 25mm, particularly preferably more than 15mN / 25mm, and more preferably more than 20mN / 25mm. By making the above-mentioned adhesion more than 10mN / 25mm, after irradiating active energy rays, it is easy to effectively suppress the workpiece after processing from accidentally falling off the workpiece processing sheet. In addition, the mirror surface of the above-mentioned silicon wafer is not an active surface. In addition, the details of the method for measuring the above-mentioned adhesion are shown in the description of the test example described later.

[0095] Further, for the workpiece processing sheet of the present embodiment, the surface of the silicon wafer is ground and the adhesive surface of the workpiece processing sheet is attached to the grinding surface after 5 minutes. After 7 days, the workpiece processing sheet is further irradiated with active energy rays, and the adhesion of the workpiece processing sheet to the above-mentioned grinding surface is preferably 500mN / 25mm or less, particularly preferably 400mN / 25mm or less, and further preferably 300mN / 25mm or less. By making the above-mentioned adhesion less than 500mN / 25mm, even in the case of using a workpiece with an active surface as a workpiece, it is easy to separate the processed workpiece from the workpiece processing sheet well. For the workpiece processing sheet of the present embodiment, as described above, by making the adhesive layer be composed of an adhesive formed by using an adhesive composition containing alkylene glycol modified rosin ester, even for the active surface of the workpiece, the above-mentioned adhesion can be achieved. In addition, the above-mentioned adhesion is preferably more than 10mN / 25mm, particularly preferably more than 15mN / 25mm, and more preferably more than 20mN / 25mm. By setting the adhesive force to 10 mN / 25 mm or less, it is easy to effectively suppress the workpiece from accidentally falling off the workpiece processing sheet after irradiation with active energy rays. The details of the method for measuring the adhesive force are described in the test examples described below.

[0096] 3. Method for manufacturing sheet for workpiece processing

[0097] The method for producing the workpiece processing sheet of the present embodiment is not particularly limited. A preferred production method includes preparing a laminate of an adhesive layer and a release sheet and then attaching a substrate to the adhesive layer-side surface of the laminate.

[0098] The formation of the above-mentioned laminated body can be carried out by a known method. For example, a coating liquid containing an adhesive composition for forming an adhesive layer and a solvent or a dispersion medium further contained as required is prepared, and the coating liquid is applied to the release surface of the release sheet to form a coating film, and the coating film is dried to form the adhesive layer. Thus, a laminated body of the adhesive layer and the release sheet can be obtained.

[0099] The coating of the coating liquid can be carried out by a known method, for example, a rod coating method, a blade coating method, a roller coating method, a scraper coating method, a die coating method, a gravure coating method, etc. can be used. In addition, as long as the coating liquid can be coated, its properties are not particularly limited, and sometimes the component used to form the adhesive layer is contained as a solute, and sometimes the component used to form the adhesive layer is contained as a dispersion medium. In addition, the release sheet can be peeled off as a process material, and the adhesive layer can also be protected until it is attached to the workpiece.

[0100] When the adhesive composition for forming the adhesive layer contains a crosslinking agent (E), it is preferred to change the above-mentioned drying conditions (temperature, time, etc.) or to provide a heat treatment so that the active energy ray-curable polymer (A) in the coating film and the crosslinking agent (E) undergo a crosslinking reaction to form a crosslinked structure in the adhesive layer at a desired density. Furthermore, in order to allow the crosslinking reaction to proceed sufficiently, the laminate can be bonded to the substrate and then left to mature for several days, for example, at 23°C and a relative humidity of 50%.

[0101] 4. How to use the workpiece processing sheet

[0102] The workpiece processing sheet of the present embodiment can be used to process a workpiece. That is, after the adhesive surface of the workpiece processing sheet of the present embodiment is attached to a single surface of the workpiece, the workpiece processing can be performed on the workpiece processing sheet. Examples of such processing include back grinding, cutting, expanding, picking up, and the like. The above-mentioned cutting can be, for example, blade cutting using a rotating circular blade; it can also be laser cutting in which a semiconductor wafer is completely cut by irradiating a laser; it can also be stealth cutting in which a modified layer is formed in the semiconductor wafer by irradiating a laser, and then the semiconductor wafer is stretched to split the semiconductor wafer along the modified layer. The workpiece processing sheet of the present embodiment can be used as a back grinding sheet, a cutting sheet, an expanding sheet, a picking up sheet, and the like according to the type of processing.

[0103] 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. Here, for the workpiece processing sheet of the present embodiment, as described above, even when the adhesive surface is attached to the active surface of a workpiece having an active surface, the increase in the adhesion of the workpiece processing sheet to the active surface can be well suppressed. Therefore, the workpiece processing sheet of the present embodiment is suitable for use in the processing of workpieces having an active surface (especially the ground surface of a semiconductor wafer within 120 minutes after the surface is ground). 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 after the surface is ground) and a normal workpiece without an active surface (especially the surface other than the ground surface of a semiconductor wafer within 120 minutes after the surface is ground).

[0104] When the workpiece processing is completed 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.

[0105] As the above-mentioned active energy ray, for example, a ray having an energy quantum in an electromagnetic wave or a charged particle beam can be used, specifically, ultraviolet rays or electron beams can be used. Ultraviolet rays that are easy to handle are particularly preferred. Ultraviolet irradiation can be performed using a high-pressure mercury lamp, a xenon lamp, an LED, etc., and the irradiation amount of ultraviolet rays is preferably 50 mW / cm in terms of illuminance. 2 Above, 1000mW / cm 2 In addition, the light intensity is preferably 50 mJ / cm 2 Above, particularly preferably 80 mJ / cm 2 More preferably, 200 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 electron beam irradiation can be performed using 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.

[0106] The workpiece processing sheet of this embodiment is particularly preferably used in a method for manufacturing a semiconductor device having the following steps. That is, the method for manufacturing a semiconductor device has: a grinding step of grinding the surface of a semiconductor wafer; a step of attaching the workpiece processing sheet of this embodiment to the ground surface of the semiconductor wafer; a step of dicing the semiconductor wafer on the workpiece processing sheet to obtain a plurality of semiconductor chips; a step of irradiating the adhesive layer of the workpiece processing sheet with active energy rays; and a step of picking up each of the semiconductor chips from the workpiece processing sheet.

[0107] The above-mentioned grinding process can be performed using a conventionally known technique. For example, the adhesive surface of the desired adhesive sheet (which may also be a workpiece processing sheet of the present embodiment) is attached to one surface of the semiconductor wafer, and a grinding device is used to grind the other surface of the semiconductor wafer on the adhesive sheet. The degree of grinding at this time can be selected according to the purpose, for example, grinding until the thickness or surface state of the semiconductor wafer reaches a predetermined degree. After the grinding, the ground surface can also be subjected to conventionally known surface treatment.

[0108] 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 semiconductor wafer, the specific technique is not limited. Here, the time from the grinding of the surface of the semiconductor wafer 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 semiconductor wafer 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 in the pickup process described later, it can be picked up well.

[0109] The subsequent cutting process can be performed using a conventionally known method. That is, a cutting device is used to cut the semiconductor wafer on the workpiece processing sheet to obtain a plurality of semiconductor chips. The type of cutting is not particularly limited, and can be, for example, blade cutting, laser cutting, stealth cutting, etc.

[0110] The irradiation with active energy rays in the active energy ray irradiation step can be performed using a conventionally known method. The types of active energy rays and irradiation conditions are as described above.

[0111] Picking up in the subsequent picking up process can also be performed using a conventionally known method. For example, a pick-up device is used to expand the workpiece processing sheet, and at the same time, a push pin is used to lift up the semiconductor chip from the back of the workpiece processing sheet, and the semiconductor chip is further picked up using a suction nozzle, thereby enabling picking up. According to the workpiece processing sheet of this embodiment, an excessive increase in the adhesion to the semiconductor wafer and the semiconductor chip obtained by processing the semiconductor wafer can be suppressed, thereby avoiding problems such as being unable to pick up the semiconductor chip, and enabling good picking up.

[0112] The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments also covers all design changes and equivalents within the technical scope of the present invention.

[0113] For example, another layer may be present on the surface of the substrate opposite to the adhesive layer or between the substrate and the adhesive layer.

[0114] Example

[0115] 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.

[0116] [Example 1]

[0117] (1) Preparation of acrylic polymers

[0118] After adding 0.25 parts by mass of azobisisobutyronitrile (initiator) to 45 parts by mass of 2-methoxyethyl acrylate, 25 parts by mass of methyl acrylate, and 30 parts by mass of 2-hydroxyethyl acrylate, polymerization was carried out by solution polymerization under a nitrogen atmosphere to obtain a (meth)acrylate polymer. The (meth)acrylate polymer was reacted with methacryloyloxyethyl isocyanate (MOI) in an amount equivalent to 80 mol% relative to 2-hydroxyethyl acrylate constituting the (meth)acrylate polymer to obtain an acrylic polymer having an active energy ray curable group introduced into the side chain. The weight average molecular weight (Mw) of the acrylic polymer was 500,000.

[0119] (2) Preparation of thickener

[0120] 711 g of rosin, 107 g of glycerin, 189 g of fumaric acid, 2100 g of polypropylene glycol with a weight average molecular weight of 1000 and 150 g of xylene were placed in a flask, replaced with nitrogen, and heated at 280° C. for 13 hours with stirring. Then, the xylene was removed under reduced pressure at 200° C. for 20 minutes. Next, the contents were taken out of the flask, cooled to room temperature and solidified, thereby obtaining an alkylene glycol-modified rosin ester as a tackifier.

[0121] (3) Preparation of adhesive composition

[0122] 100 parts by mass of the acrylic polymer having an active energy ray-curable group introduced into the side chain obtained in the above (1) (solid content conversion value; the same applies hereinafter), 2 parts by mass of the alkylene glycol-modified rosin ester obtained in the above (2) as a tackifier, 0.5 parts by mass of trimethylolpropane-modified toluene diisocyanate (manufactured by TOSOH CORPORATION, product name "CORONATE L") as a crosslinking agent, and 0.3 parts by mass of 2,2-dimethoxy-1,2-diphenylethane-1-one (manufactured by BASF, product name "Omnirad 651") as a photopolymerization initiator were mixed in a solvent to obtain a coating liquid of an adhesive composition having a solid content concentration of 30% by mass.

[0123] (4) Formation of Adhesive Layer

[0124] The coating liquid of the adhesive composition prepared in the above (3) was applied using a comma coater onto the release surface of a release sheet (manufactured by LINTEC CORPORATION, product name "SP-PET3801") having a silicone release agent layer formed on one side of a polyethylene terephthalate film having a thickness of 38 μm, and dried by heating at 90°C for 1 minute to form an adhesive layer having a thickness of 5 μm on the release sheet.

[0125] (5) Production of workpiece processing sheets

[0126] The exposed surface of the adhesive layer formed in (4) was bonded to one surface of an ethylene-methacrylic acid copolymer film having a thickness of 80 μm as a substrate, and then allowed to stand for 1 week in an environment of 23° C. and a relative humidity of 50%, thereby obtaining a workpiece processing sheet.

[0127] Here, the weight average molecular weight (Mw) is a weight average molecular weight in terms of standard polystyrene measured under the following conditions using gel permeation chromatography (GPC) (GPC measurement).

[0128] <Measurement conditions>

[0129] ·GPC measuring apparatus: manufactured by TOSOH CORPORATION, HLC-8320

[0130] ·GPC columns (passed in the following order): manufactured by TOSOH CORPORATION

[0131] TSK gel superH-H

[0132] TSK gel superHM-H

[0133] TSK gel superH2000

[0134] ·Test solvent: tetrahydrofuran

[0135] ·Measurement temperature: 40℃

[0136] [Examples 2 to 11, Comparative Examples 1 to 11]

[0137] Except having changed the composition of an acrylic polymer, and the kind and content of a tackifier into what is described in Table 1, it carried out similarly to Example 1, and produced the sheet for workpiece|work processing.

[0138] [Test Example 1] (Measurement of Adhesion to a Normal Surface)

[0139] The workpiece processing sheet manufactured in the embodiment and the comparative example was cut into short strips of 25 mm width. The peeling sheet was peeled off from the obtained short strip workpiece processing sheet, and the adhesive surface of the exposed adhesive layer was attached to the mirror surface of the mirror-finished silicon wafer using a 2 kg rubber roller under an environment of a temperature of 23°C and a relative humidity of 50%, and the exposed adhesive layer was left to stand for 20 minutes as a sample for measurement. In addition, the mirror surface in the above silicon wafer is a surface (ordinary surface) whose activity has disappeared after more than 1 month after grinding.

[0140] For the obtained measurement sample, 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 adhesion (mN / 25 mm) to the silicon wafer was measured by the 180° peeling method based on JIS Z0237:2009. The adhesion obtained in this way was recorded as the adhesion to the ordinary surface before UV irradiation and is shown in Table 2.

[0141] Furthermore, the adhesive layer of the sample for measurement obtained in the same manner as above was irradiated with ultraviolet rays (UV) (illuminance: 230 mW / cm 2 , light intensity: 190mJ / cm 2 ) to cure the adhesive layer. Then, the adhesive force to the silicon wafer was measured in the same manner as above (mN / 25 mm). The adhesive force thus obtained was recorded as the adhesive force to the ordinary surface after UV irradiation and is shown in Table 2.

[0142] [Test Example 2] (Measurement of Adhesion to Active Surface)

[0143] Using a grinding device (manufactured by DISCO Corporation, product name "DFG8540"), a single side of the silicon wafer was ground until the thickness of the silicon wafer became 500 μm. The adhesive surface of the short strip-shaped workpiece processing sheet obtained in the same manner as in Example 1 was attached to the grinding surface (active surface) activated by the grinding as a sample for measurement. In addition, the workpiece processing sheet was attached to the above-mentioned active surface within 5 minutes after the above-mentioned grinding.

[0144] The sample was left to stand for 7 days in an environment with a temperature of 23°C and a relative humidity of 50%, and then irradiated with ultraviolet light (UV) (illuminance: 230 mW / cm 2 , light intensity: 190mJ / cm 2 ) to cure the adhesive layer. Then, the adhesion to the silicon wafer (mN / 25 mm) was measured in the same manner as in Example 1. The adhesion thus obtained was recorded as the adhesion to the active surface (after standing for 7 days and UV irradiation) and is shown in Table 2.

[0145] [Test Example 3] (Evaluation of cutting properties)

[0146] Using a grinding device (manufactured by DISCO Corporation, product name "DFG8540"), a single side of the silicon wafer was ground until the thickness of the silicon wafer became 150 μm and a #2000 grinding surface was obtained. The peeling sheet was peeled off from the workpiece processing sheet manufactured in the embodiment and the comparative example, and the adhesive surface of the exposed adhesive layer was attached to the grinding surface (active surface) activated by the grinding using a laminator. In addition, the attachment was performed within 5 minutes after the above grinding.

[0147] 20 minutes after the above-mentioned attachment, cutting was performed under the following conditions.

[0148] <Cutting conditions>

[0149] Cutting device: DFD-6362 manufactured by DISCO Corporation

[0150] Blade: NBC-2H 2050 27HECC manufactured by DISCO Corporation

[0151] Blade width: 0.025~0.030mm

[0152] Blade extension: 0.640~0.760mm

[0153] Blade speed: 35000rpm

[0154] Cutting speed: 60 mm / s

[0155] ·Substrate cut depth: 70μm

[0156] Cutting water volume: 1.0L / min

[0157] Cutting water temperature: 20℃

[0158] Cutting size: 0.5mm square

[0159] After dicing, the ratio of chip scattering in the obtained cores (the ratio of the number of chips dropped from the workpiece processing sheet to the total number of obtained chips) was calculated, and the dicing property was evaluated based on the following criteria. The results are recorded as dicing property of active wafers and are shown in Table 2.

[0160] ○: The ratio of chip scattering is 10% or less.

[0161] △: The ratio of chip scattering is more than 10% and less than 50%.

[0162] ×: The chip scattering ratio exceeds 50%.

[0163] In addition, for the silicon wafer that was ground in the same manner as above, after grinding, the workpiece processing sheet was not attached, but was left to stand for a sufficient time. The adhesive surface of the workpiece processing sheet was attached to the grinding surface (ordinary surface) where the activity was lost in the same manner as above, and the cutting was further performed in the same manner as above to evaluate the cutting property. The results are recorded as the cutting property of the ordinary wafer and are shown in Table 2.

[0164] [Test Example 4] (Evaluation of Pickup Properties)

[0165] 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 became 150 μm. The peeling sheet was peeled off from the workpiece processing sheet manufactured in the embodiment and the comparative example, and the adhesive surface of the exposed adhesive layer was attached to the grinding surface (active surface) activated by the grinding using a laminator. In addition, the attachment was performed within 5 minutes after the above grinding.

[0166] After the above-mentioned attachment, the film was left to stand for 7 days in an environment with a temperature of 23° C. and a relative humidity of 50%, and then cut under the following conditions.

[0167] <Cutting conditions>

[0168] Cutting device: DFD-6362 manufactured by DISCO Corporation

[0169] Blade: NBC-2H 2050 27HECC manufactured by DISCO Corporation

[0170] Blade width: 0.025~0.030mm

[0171] Blade extension: 0.640~0.760mm

[0172] Blade speed: 35000rpm

[0173] Cutting speed: 60 mm / s

[0174] ·Substrate cut depth: 70μm

[0175] Cutting water volume: 1.0L / min

[0176] Cutting water temperature: 20℃

[0177] Cutting size: 10mm square

[0178] Furthermore, the adhesive layer in the workpiece processing sheet was irradiated with ultraviolet rays (UV) (illuminance: 230 mW / cm 2 , light intensity: 190mJ / cm 2 ) to cure the adhesive layer.

[0179] Next, a pick-up device is used to try to pick up one of the multiple chips obtained by the above-mentioned cutting that is located near the center when looking down at the workpiece processing sheet. Specifically, the chip is lifted up with a pin at a lifting height of 500 μm from the surface on the substrate side of the workpiece processing sheet, and the surface of the chip on the opposite side of the workpiece processing sheet is adsorbed by a vacuum suction nozzle, 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 criteria. The results are recorded as the pick-up property of the active wafer and are shown in Table 2.

[0180] ○: The chip can be separated.

[0181] ×: Failed to separate the chip.

[0182] In addition, for the silicon wafers subjected to the same grinding as above, after grinding, the workpiece processing sheet was not attached, but was left to stand for a sufficient time. The adhesive surface of the workpiece processing sheet was attached to the grinding surface (ordinary surface) where the activity was lost in the same manner as above, and further cutting, ultraviolet irradiation and picking were performed in the same manner as above, and the picking property was evaluated. The results are recorded as the picking property of ordinary wafers and are shown in Table 2.

[0183] In addition, the details of the abbreviations and the like described in Table 1 are as follows.

[0184] [Composition of active energy ray-curable polymer]

[0185] MEA: 2-methoxyethyl acrylate (glass transition temperature Tg: -50°C)

[0186] MA: Methyl acrylate (glass transition temperature Tg: 10°C)

[0187] HEA: 2-Hydroxyethyl acrylate (glass transition temperature Tg: -15°C)

[0188] 2EHA: 2-ethylhexyl acrylate (glass transition temperature Tg: -70°C)

[0189] VAc: Vinyl acetate (glass transition temperature Tg: 28°C)

[0190] iso-STA: Isooctadecyl acrylate (glass transition temperature Tg: -18°C)

[0191] BA: n-butyl acrylate (glass transition temperature Tg: -55°C)

[0192] ACMO: Acryloylmorpholine (glass transition temperature Tg: 145°C)

[0193] MMA: Methyl methacrylate (glass transition temperature Tg: 105°C)

[0194] MOI: Methacryloyloxyethyl isocyanate

[0195] [Thickener]

[0196] Alkylene glycol-modified rosin ester: rosin ester prepared according to step (2) of Example 1

[0197] Terpene phenol T-100: Terpene phenol (manufactured by YASUHARA CHEMICAL CO., LTD., "T-100")

[0198] Terpene phenol T-130: Terpene phenol (manufactured by YASUHARA CHEMICAL CO., LTD., "T-130")

[0199] Terpene phenol T-160: Terpene phenol (manufactured by YASUHARA CHEMICAL CO., LTD., "T-160")

[0200] Petroleum resin FTR6100: Styrene monomer / aliphatic monomer copolymer (manufactured by Mitsui Chemicals, Inc., product name "FTR6100")

[0201] Petroleum resin FTR7100: Styrene monomer / α-methylstyrene aliphatic monomer copolymer (manufactured by Mitsui Chemicals, Inc., product name "FTR7100")

[0202] Acid-modified rosin ester: Acid-modified rosin ester (manufactured by Arakawa Chemical Industries, Ltd., product name "PINECRYSTAL KE-604")

[0203] Hydrogenated rosin ester KE-311: Hydrogenated rosin ester (manufactured by Arakawa Chemical Industries, Ltd., product name "PINECRYSTAL KE-311")

[0204] Hydrogenated rosin ester KE-359: Hydrogenated rosin ester (manufactured by Arakawa Chemical Industries, Ltd., product name "PINECRYSTAL KE-359")

[0205] Polyglycerol: Polyglycerol (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., product name "PG310-6EO")

[0206] [Table 1]

[0207]

[0208] [Table 2]

[0209]

[0210] As is apparent from Table 2, the workpiece processing sheet of the Example exhibits excellent pickup properties for the active surface of the wafer. In addition, the workpiece processing sheet of the Example also exhibits excellent pickup properties for a common wafer having no active surface.

[0211] Industrial Applicability

[0212] 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 base material and an adhesive layer laminated on one side of the base material, wherein: The adhesive layer is composed of an active energy ray-curable adhesive, and the active energy ray-curable adhesive is formed of an adhesive composition containing at least an acrylic polymer and a tackifier. The tackifier is alkylene glycol modified rosin ester.

2. The workpiece processing sheet according to claim 1, characterized in that: The content of the tackifier in the adhesive composition is 0.005 parts by mass or more and 15 parts by mass or less relative to 100 parts by mass of the acrylic polymer.

3. The workpiece processing sheet according to claim 1, characterized in that: The softening point of the tackifier is -100°C or higher and 50°C or lower.

4. The workpiece processing sheet according to claim 1, characterized in that: The weight average molecular weight of the tackifier is 1,000 or more.

5. The workpiece processing sheet according to claim 1, characterized in that: Before the workpiece processing sheet is irradiated with active energy rays, the adhesive force of the workpiece processing sheet to the mirror surface of the silicon wafer is 200 mN / 25 mm or more and 20000 mN / 25 mm or less.

6. The workpiece processing sheet according to claim 1, characterized in that: The acrylic polymer has active energy ray-curing properties.

7. The workpiece processing sheet according to claim 1, characterized in that: The acrylic polymer contains, as monomer units constituting the acrylic polymer, 10% by mass or more of a monomer having a homopolymer glass transition temperature Tg of -30°C or less and 3% by mass or more of a monomer having a homopolymer glass transition temperature Tg of 10°C or more.

8. The workpiece processing sheet according to claim 7, characterized in that: The monomer having a homopolymer having a glass transition temperature Tg of 10° C. or higher is at least one monomer selected from the group consisting of methyl acrylate, methyl methacrylate, acryloylmorpholine, vinyl acetate and 2-hydroxyethyl methacrylate.

9. The workpiece processing sheet according to claim 1, characterized in that: The workpiece processing sheet is attached to the polished surface of the semiconductor wafer within 120 minutes after the surface is polished.

10. The workpiece processing sheet according to claim 1, wherein: The workpiece processing sheet can be attached to the ground surface of the semiconductor wafer within 120 minutes after the surface is ground and to surfaces other than the ground surface.

11. A method for manufacturing a semiconductor device, characterized in that: It has: A lapping process for lapping the surface of a semiconductor wafer; A step of attaching the workpiece processing sheet according to any one of claims 1 to 10 to the polished surface of the semiconductor wafer; A dicing step of dicing the semiconductor wafer on the workpiece processing sheet to obtain a plurality of semiconductor chips; an active energy ray irradiation step of irradiating the adhesive layer in the workpiece processing sheet with active energy rays; and A picking-up step of picking up each of the semiconductor chips from the workpiece processing sheet.

12. The method for manufacturing a semiconductor device according to claim 11, wherein: The workpiece processing sheet is attached to the semiconductor wafer in the attaching step within 120 minutes after the surface of the semiconductor wafer is polished in the polishing step.

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