Sheet for workpiece processing

Abstract

To provide a workpiece processing sheet which suppresses an adhesive residue on a workpiece.SOLUTION: There are provided workpiece processing sheets 1A, 1B, 1C comprising substrates 11a, 11b, 11c and an adhesive layer 12 laminated on one surface side of the substrates 11a, 11b, 11c, wherein the content of a tin atom in the adhesive layer 12 is 0.002 mass% or more and 0.015 mass% or less.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Semiconductor wafers such as silicon and gallium arsenide, and various packages are manufactured in a large-diameter state, cut (diced) into chips, peeled off (picked up), and then transferred to the next mounting process. At this time, a work such as a semiconductor wafer is laminated on an adhesive sheet having a substrate and an adhesive layer (hereinafter sometimes referred to as a "work processing sheet"), and processed such as back grinding, dicing, cleaning, drying, expanding, picking up, and mounting.

[0003] When a sheet having an adhesive layer exhibiting active energy ray curability is used as the work processing sheet, the adhesive force can be reduced by irradiating active energy rays, and the work processing sheet can be easily peeled off from the processed work. Patent Document 1 discloses such a work processing sheet.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, the work processing sheet may become charged during conveyance or use, and such charging can cause damage to semiconductor chips and malfunctions in dicing devices, etc. For example, when separating a processed work from the work processing sheet, static electricity called peeling charge may be generated between the work processing sheet and the processed work. The generation of such static electricity causes damage to circuits formed on the chip when the processed work is, for example, a semiconductor chip.

[0006] Therefore, consideration is also being given to providing the work processing sheet with an antistatic function to prevent charging. For example, it has been considered to provide an antistatic layer containing an antistatic agent between the base material and the adhesive layer. However, in the work processing sheet provided with such an antistatic layer, when separating the processed work from the work processing sheet, the inventors have confirmed that a phenomenon in which the adhesive constituting the adhesive layer adheres to the processed work (hereinafter sometimes referred to as "adhesive residue") is likely to occur.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a work processing sheet with reduced adhesive residue on the work.

Means for Solving the Problems

[0008] In order to achieve the above object, first, the present invention provides a work processing sheet including a base material and an adhesive layer laminated on one side of the base material, wherein the content of tin atoms in the adhesive layer is 0.002% by mass or more and 0.015% by mass or less (Invention 1).

[0009] In the work processing sheet according to the above invention (Invention 1), since the content of tin atoms in the adhesive layer is within the above range, even when the base material includes an antistatic layer (including the "organic conductive film" described later), the adhesion of the adhesive layer to the base material (or the antistatic layer) is good, and the occurrence of adhesive residue on the processed work separated from the adhesive layer is suppressed.

[0010] In the above invention (Invention 1), it is preferable that the adhesive layer is composed of an active energy ray curable adhesive (Invention 2).

[0011] In the above invention (Invention 2), it is preferable that the active energy ray curable adhesive contains a polymer having active energy ray curability and a tin-containing catalyst containing a tin atom (Invention 3).

[0012] In the above invention (Invention 3), the polymer having active energy ray curability is a (meth)acrylate polymer in which an active energy ray curable group is introduced into the side chain, and the (meth)acrylate polymer is obtained by reacting an acrylic copolymer having a functional group-containing monomer unit with an unsaturated group-containing compound having a functional group bonded to the functional group by the catalytic action of the tin-containing catalyst. It is preferably (Invention 4).

[0013] In the above inventions (Inventions 1 to 4), the surface resistivity of the surface of the base material on the side where the adhesive layer is laminated is 1×10 10 Ω / square or less is preferable (Invention 5).

[0014] In the above inventions (Inventions 1 to 5), it is preferable that the base material is provided with an organic conductive film on the surface on the side where the adhesive layer is laminated (Invention 6).

[0015] In the above inventions (Inventions 1 to 6), it is preferably used for dicing (Invention 7).

Advantages of the Invention

[0016] The sheet for work processing according to the present invention can suppress adhesive residue on the work.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described. The sheet for workpiece processing according to this embodiment includes a base material and an adhesive layer laminated on one side of the base material. And in the sheet for workpiece processing according to this embodiment, the content of tin atoms in the adhesive layer is 0.002% by mass or more and 0.015% by mass or less.

[0019] Generally, in the use of a sheet for workpiece processing, after a workpiece is attached to the surface of the adhesive layer of the sheet for workpiece processing on the side opposite to the base material (hereinafter sometimes referred to as the "adhesive surface"), a predetermined process is performed on the workpiece on the sheet for workpiece processing. Subsequently, (when the adhesive layer is made of an active energy ray curable adhesive, after irradiating the adhesive layer with active energy rays to cure the adhesive layer,) the processed workpiece is separated from the sheet for workpiece processing. At the time of this separation, in the conventional sheet for workpiece processing, adhesive residue as described above was likely to occur.

[0020] However, in the sheet for workpiece processing according to this embodiment, since the content of tin atoms in the adhesive layer is within the above range, the adhesion between the base material and the adhesive layer is improved. Thereby, the occurrence of peeling at the interface between the base material and the adhesive layer accompanying the separation of the workpiece from the sheet for workpiece processing is suppressed. As a result, adhesion of the adhesive constituting the adhesive layer to the separated workpiece is suppressed. That is, adhesive residue on the workpiece is well suppressed.

[0021] Also, as a general means of improving the adhesion between the base material and the adhesive layer, surface treatment such as corona treatment may be performed on the surface of the base material where the adhesive layer is provided. However, when a film (organic conductive film) for the purpose of antistatic is provided on the surface of the base material, surface treatment such as corona treatment cannot be performed on the surface of the organic conductive film from the viewpoint of avoiding damage to the organic conductive film. Therefore, when using a base material provided with the above-described organic conductive film, there has been a problem that glue residue is particularly likely to occur.

[0022] However, according to the sheet for work processing according to the present embodiment, even when it is not possible to perform surface treatment for enhancing the adhesion between the base material and the adhesive layer on the base material as in the case of providing an organic conductive film on the surface of the base material, excellent adhesion between the base material and the adhesive layer can be achieved, and the occurrence of glue residue can be effectively suppressed.

[0023] From the viewpoint of further enhancing the adhesion between the base material and the adhesive layer, the upper limit value of the content of tin atoms in the adhesive layer is preferably 0.014% or less, and particularly preferably 0.013% or less. Also, from the same viewpoint, the lower limit value of the content of tin atoms in the adhesive layer is preferably 0.0022% or more, and particularly preferably 0.0024% or more.

[0024] Note that the origin of the tin atoms in the adhesive layer in the present embodiment may be a tin-containing catalyst as a material for forming the adhesive layer, as described later. In this case, by adjusting the amount of the tin-containing catalyst used so that the content of tin atoms in the adhesive layer falls within the above-described range, it is possible to obtain a sheet for work processing that can satisfactorily suppress glue residue while achieving desired performance such as adhesiveness.

[0025] The content of tin atoms in the adhesive layer in the present embodiment may be determined by quantitative analysis, or may be calculated and determined from the composition of the material (for example, the adhesive composition described later) used for forming the adhesive layer.

[0026] Although the types of the above quantitative analysis are not particularly limited, the following method can be mentioned as an example. First, 50 mg of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is collected and pretreated by a pressurized acid decomposition method. Then, the content of tin atoms in the pressure-sensitive adhesive can be obtained by inductively coupled plasma mass spectrometry (ICP-MS) (for example, an apparatus manufactured by Agilent Technologies is used).

[0027] Examples of the work on which the work processing sheet according to the present embodiment is used include semiconductor members such as semiconductor chips, semiconductor wafers, and semiconductor packages, and glass members such as glass chips and glass plates.

[0028] 1. Constituent members of the work processing sheet Examples of the work processing sheet according to the present embodiment are shown in FIGS. 1 to 3. The work processing sheet 1A shown in FIG. 1 includes a base material 11a in which organic conductive films 112 are provided on both surfaces of a base film 111, and a pressure-sensitive adhesive layer 12 laminated on one side of the base material 11a.

[0029] The work processing sheet 1B shown in FIG. 2 includes a base material 11b in which an organic conductive film 112 is provided on one surface of a base film 111, and a pressure-sensitive adhesive layer 12 laminated on the surface of the base material 11a where the organic conductive film 112 is provided.

[0030] The work processing sheet 1C shown in FIG. 3 includes a base material 11c made of a base film 111' containing an antistatic agent, and a pressure-sensitive adhesive layer 12 laminated on one side of the base material 11c.

[0031] (1) Base material The base material in this embodiment is not particularly limited as long as it exhibits the desired functions in the process of using the workpiece processing sheet. As shown in FIGS. 1 and 2, the base material in this embodiment may include an organic conductive film 112 on both sides or one side of the base film 111, or may consist only of the base film 111' containing an antistatic agent as shown in FIG. 3. Further, the base material in this embodiment may consist only of the base film 111 that does not include the organic conductive film 112 and does not contain an antistatic agent, or may include the organic conductive film 112 on both sides or one side of the base film 111' containing an antistatic agent.

[0032] In the workpiece processing sheet according to this embodiment, as described above, even when the surface treatment for improving the adhesion between the base material and the adhesive layer cannot be performed on the base material, the occurrence of glue residue can be effectively suppressed. Therefore, as shown in FIGS. 1 and 2, it is preferable that the base material in this embodiment includes the organic conductive film 112 in terms of the high benefit of the glue residue suppression effect.

[0033] (1-1) Base film The base film 111 is preferably a resin film mainly made of a resin-based material. Specific examples thereof include ethylene-vinyl acetate copolymer films; ethylene-(meth)acrylic acid copolymer films, ethylene-(meth)acrylic acid methyl copolymer films, and other ethylene-(meth)acrylic acid ester copolymer films such as ethylene-based copolymer films; polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, ethylene-norbornene copolymer films, norbornene resin films and other polyolefin-based films; polyvinyl chloride films, polyvinyl chloride copolymer films and other polyvinyl chloride-based films; polyethylene terephthalate films, polybutylene terephthalate films, polyethylene naphthalate and other polyester-based films; (meth)acrylic acid ester copolymer films; polyurethane films; polyimide films; polystyrene films; polycarbonate films; fluororesin films and the like. Examples of the polyethylene film include low-density polyethylene (LDPE) films, linear low-density polyethylene (LLDPE) films, high-density polyethylene (HDPE) films and the like. Also, modified films such as these crosslinked films and ionomer films are also used. Further, preferred examples of the base film 111' include those obtained by incorporating an antistatic agent into these films. When the adhesive layer 12 is made of an active energy ray-curable adhesive, the base film 111 and the base film 111' are preferably made of a material that exhibits good transparency to the active energy rays irradiated for curing the adhesive layer 12.

[0034] Further, the base film 111 may be a laminated film formed by laminating a plurality of the above-described films. In this laminated film, the materials constituting each layer may be the same or different. The base film 111' may also be a laminated film. In this case, all the layers constituting each layer may contain an antistatic agent, or at least one layer may contain an antistatic agent.

[0035] As the base film 111, among the above-mentioned films, from the viewpoint of excellent flexibility, it is preferable to use an ethylene-methyl methacrylate copolymer film. Also for the base film 111', it is preferable to use an ethylene-methyl methacrylate copolymer film containing an antistatic agent. In addition, "(meth)acrylic acid" in this specification means both acrylic acid and methacrylic acid. The same applies to other similar terms.

[0036] The base film 111 may contain various additives such as a flame retardant, a plasticizer, an antistatic agent, a lubricant, an antioxidant, a colorant, an infrared absorber, an ultraviolet absorber, and an ion scavenger. Although the content of these additives is not particularly limited, it is preferably within a range in which the base film 111 exhibits desired functions. Also for the base film 111', in addition to the antistatic agent, it may contain the various additives described above.

[0037] On the surface of the base film 111 where the organic conductive film 112 is laminated, surface treatment such as primer treatment, corona treatment, or plasma treatment may be performed to enhance the adhesion to the organic conductive film 112.

[0038] (1-2) Organic conductive film The organic conductive film 112 is not particularly limited as long as it can exhibit desired functions such as antistatic properties.

[0039] The organic conductive film 112 preferably contains a conductive material and a binder resin. Examples of the conductive material include conductive polymers, conductive fillers, anionic and cationic compounds, and compounds having a quaternary ammonium base in the main chain or side chain of the molecule.

[0040] Examples of the conductive polymer include polythiophene-based, polyaniline-based, or polypyrrole-based conductive polymers. Examples of the polythiophene-based conductive polymer include polythiophene, poly(3-alkylthiophene), poly(3-thiophene-β-ethanesulfonic acid), a mixture of polyalkylenedioxythiophene and polystyrenesulfonate, and the like. Examples of the polyalkylenedioxythiophene include polyethylene dioxythiophene, polypropylene dioxythiophene, poly(ethylene / propylene) dioxythiophene, and the like. Examples of the polyaniline-based conductive polymer include polyaniline, polymethylaniline, polymethoxyaniline, and the like. Examples of the polypyrrole-based conductive polymer include polypyrrole, poly3-methylpyrrole, poly3-octylpyrrole, and the like. These conductive polymer compounds may be used alone or in combination of two or more. These conductive polymers are preferably dispersed in water and used in the form of an aqueous solution.

[0041] Examples of the conductive filler include particles of gold, silver, copper, nickel, aluminum, stainless steel, carbon, conductive ceramics, tin oxide, antimony-doped tin oxide (ATO), indium oxide-tin oxide (ITO), zinc oxide, antimony pentoxide, and the like.

[0042] Examples of the anionic or cationic compound include ionic liquids, ionic solids, anionic surfactants, alkali metal salts, cationic surfactants, nonionic surfactants, and the like. Examples of the ionic liquid and the ionic solid include nitrogen-containing onium salts, sulfur-containing onium salts, phosphorus-containing onium salts, and the like. Examples of the alkali metal salt include lithium salts, potassium salts, and the like. These may be used alone or in combination of two or more.

[0043] Examples of the compound having a quaternary ammonium base include, specifically, a pyrrolidium ring, a quaternized product of an alkylamine, a copolymer of these with acrylic acid or methacrylic acid, a quaternized product of N-alkylaminoacrylamide, a vinylbenzyltrimethylammonium salt, a 2-hydroxy-3-methacryloxypropyltrimethylammonium salt, and the like.

[0044] The compound having the quaternary ammonium base is preferably a polymer compound. The number average molecular weight of the compound having the quaternary ammonium base is preferably 1000 or more, particularly preferably 2000 or more, and more preferably 5000 or more. Regarding the upper limit of the number average molecular weight, from the viewpoint of preventing the viscosity of the coating liquid containing the conductive material from becoming too high, the number average molecular weight is preferably 500000 or less. The number average molecular weight in this specification is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC).

[0045] The content of the conductive material in the organic conductive film 112 is preferably 1% by mass or more, particularly preferably 5% by mass or more. Also, the content is preferably 30% by mass or less, particularly preferably 20% by mass or less. When the content of the conductive material is 1% by mass or more, desired functions such as antistatic properties are effectively exhibited. Also, when the content of the conductive polymer is 30% by mass or less, the ratio of the binder resin in the organic conductive film 112 becomes sufficient, and the coating film strength of the organic conductive film 112 itself becomes good.

[0046] Examples of the binder resin include, for example, melamine resin, polyester, polyurethane, acrylic resin, vinyl resin, epoxy resin, amide resin, polyvinyl alcohol, and the like. Examples of the melamine resin include, for example, methylated melamine resin, butylated melamine resin, methyl / butylated melamine resin, and the like. Among these, it is preferable to use butylated melamine resin. These binder resins may have a composite structure in the skeletal structure by copolymerization or the like. Examples of the binder resin having a composite structure include, for example, acrylic resin graft polyester, acrylic resin graft polyurethane, vinyl resin graft polyester, vinyl resin graft polyurethane, and the like.

[0047] The organic conductive film 112 may further contain a crosslinkable compound. The crosslinkable compound is obtained by incorporating a crosslinking agent into a coating solution containing a conductive material and causing a crosslinking reaction with the functional groups of the compounds contained in the coating solution. By incorporating a crosslinking agent into the coating solution, the water resistance, solvent resistance, mechanical strength, etc. of the organic conductive film 112 are improved.

[0048] Examples of the crosslinking agent include melamine-based crosslinking agents and epoxy-based crosslinking agents. Examples of the melamine-based crosslinking agent include methoxymethylated melamine, butoxymethylated melamine, which are alkylol or alkoxyalkylolated melamine-based compounds, and those obtained by co-condensing urea or the like with a part of melamine may also be used. As the epoxy-based crosslinking agent, it is preferable to use a compound having an epoxy group that is water-soluble or has a water solubilization rate of 50% or more.

[0049] The organic conductive film 112 may contain at least one of additives such as an antifoaming agent, a coating property improver, a thickener, an organic lubricant, organic particles, and inorganic particles, if necessary.

[0050] The organic conductive film 112 can be formed by applying a coating solution containing the above-described conductive polymer, binder resin, etc. to one or both sides of the base film 111 and drying the obtained coating film.

[0051] Although the thickness of the organic conductive film 112 can be appropriately set according to the method of using the workpiece processing sheet, it is usually preferably 0.003 μm or more, particularly preferably 0.005 μm or more. Also, the thickness is preferably 1.5 μm or less, particularly preferably 0.5 μm or less.

[0052] (1-3) Antistatic agent in the base film When the base material according to this embodiment consists only of the base film 111' containing an antistatic agent, the antistatic agent contained in the base film 111' is not particularly limited as long as it can impart a desired antistatic property.

[0053] Preferred antistatic agents include low molecular weight antistatic agents, high molecular weight antistatic agents, metal oxides, carbon materials, etc., but high molecular weight antistatic agents are particularly preferred. Examples of the high molecular weight antistatic agent include vinyl copolymers having a sulfonate in the molecule, alkyl sulfonates, alkyl benzene sulfonates, betaines, etc. In particular, salts of inorganic proton acids of polyethers, polyamide elastomers, polyester elastomers, polyether amides or polyether ester amides can be mentioned. Examples of the salts of inorganic proton acids include alkali metal salts, alkaline earth metals, zinc salts, or ammonium salts.

[0054] The content of the antistatic agent in the base film 111' is preferably 3% by mass or more and 20% by mass or less. When the content of the antistatic agent is within the above range, the resulting base film 111' is likely to have good antistatic properties.

[0055] (1-4) Physical properties of the base material, etc. The surface resistivity of the surface of the base material 11 on the side where the adhesive layer is laminated is preferably 1×10 12 Ω / square or less, particularly preferably 5×10 11 Ω / square or less, and further preferably 1×10 11It is preferably Ω / □ or less. By the base material 11 exhibiting the surface resistivity described above, the sheet for workpiece processing is likely to exhibit excellent antistatic properties. Note that the lower limit value of the surface resistivity is not particularly limited. For example, it may be 1×10 4 Ω / □ or more, particularly 1×10 5 Ω / □ or more. Details of the method for measuring the surface resistivity are as described in the test examples described later.

[0056] Although the thickness of the base material 11 (when including the organic conductive film 112, the thickness including the organic conductive film 112) can be appropriately set according to the method in which the sheet for workpiece processing is used, it is usually preferably 20 μm or more, particularly preferably 25 μm or more. Also, the thickness is usually preferably 450 μm or less, particularly preferably 300 μm or less.

[0057] (2) Adhesive layer In the sheet for workpiece processing according to the present embodiment, the adhesive layer is not particularly limited as long as it contains tin atoms in the above-described content and can exhibit sufficient adhesive force to the adherend (particularly, the adhesive force to the workpiece sufficient for performing workpiece processing).

[0058] Examples of the adhesive constituting the adhesive layer in the present embodiment include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, polyvinyl ether adhesives, and the like. Among these, from the viewpoint of easily adjusting the content of tin atoms to the above-described range and easily exhibiting a desired adhesive force, it is preferable to use an acrylic adhesive.

[0059] Note that in the adhesive layer in the present embodiment, the above-described content of tin atoms may be achieved by adding tin alone and / or a tin-containing compound to the adhesive constituting it. Alternatively, the above-described content of tin atoms may be achieved by using a tin-containing compound (particularly, a tin-containing catalyst described later) as one of the materials of the adhesive layer.

[0060] Although the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer in the present embodiment may be a pressure-sensitive adhesive having no active energy ray curability, it is preferably a pressure-sensitive adhesive having active energy ray curability (hereinafter sometimes referred to as "active energy ray curable pressure-sensitive adhesive"). Since the pressure-sensitive adhesive layer is composed of an active energy ray curable pressure-sensitive adhesive, the pressure-sensitive adhesive layer can be cured by irradiation with active energy rays, and the adhesive force of the work processing sheet to the adherend can be easily reduced. In particular, the processed work can be easily separated from the work processing sheet by irradiation with active energy rays.

[0061] The active energy ray curable pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer may be mainly composed of a polymer having active energy ray curability, or a non-active energy ray curable polymer (a polymer having no active energy ray curability) and at least one monomer and / or oligomer having at least one active energy ray curable group. It may also be a mixture mainly composed of a polymer having active energy ray curability and a non-active energy ray curable polymer, or a mixture of a polymer having active energy ray curability and at least one monomer and / or oligomer having at least one active energy ray curable group, or a mixture of these three types.

[0062] First, the case where the active energy ray curable pressure-sensitive adhesive is mainly composed of a polymer having active energy ray curability will be described below.

[0063] The polymer having active energy ray curability is preferably a (meth)acrylate (co)polymer (A) (hereinafter sometimes referred to as "active energy ray curable polymer (A)") into which a functional group having active energy ray curability (active energy ray curable group) is introduced into the side chain. This active energy ray curable polymer (A) is preferably obtained by reacting an acrylic copolymer (a1) having a functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a functional group bonded to the functional group.

[0064] The acrylic copolymer (a1) preferably contains a structural unit derived from a functional group-containing monomer and a structural unit derived from a (meth)acrylic acid ester monomer or a derivative thereof.

[0065] The functional group-containing monomer as a structural unit of the acrylic copolymer (a1) is preferably a monomer having a polymerizable double bond and a functional group such as a hydroxy group, a carboxy group, an amino group, a substituted amino group, and an epoxy group in the molecule.

[0066] Examples of the hydroxy group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0067] Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.

[0068] Examples of the amino group-containing monomer or the substituted amino group-containing monomer include aminoethyl (meth)acrylate, n-butylaminoethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0069] The acrylic copolymer (a1) preferably contains 1% by mass or more, particularly preferably 5% by mass or more, and more preferably 10% by mass or more of the structural unit derived from the above functional group-containing monomer. Further, the acrylic copolymer (a1) preferably contains the structural unit derived from the above functional group-containing monomer at 35% by mass or less, particularly preferably 30% by mass or less. When the acrylic copolymer (a1) contains the functional group-containing monomer within the above range, it becomes easy to form the desired active energy ray-curable polymer (A).

[0070] Examples of the (meth)acrylic acid ester monomer constituting the acrylic copolymer (a1) include, in addition to the (meth)acrylic acid alkyl ester having an alkyl group with 1 to 20 carbon atoms, monomers having an alicyclic structure in the molecule (alicyclic structure-containing monomers) are preferably used.

[0071] As the above (meth)acrylic acid alkyl ester, particularly the (meth)acrylic acid alkyl ester having an alkyl group with 1 to 18 carbon atoms, for example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, etc. are preferably used. These may be used alone or in combination of two or more.

[0072] Examples of the alicyclic structure-containing monomer include cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyl oxyethyl (meth)acrylate, etc. These may be used alone or in combination of two or more.

[0073] The acrylic copolymer (a1) preferably contains 50% by mass or more, particularly preferably 60% by mass or more, and even more preferably 70% by mass or more of a structural unit derived from a (meth)acrylic acid ester monomer or its derivative. Further, the acrylic copolymer (a1) preferably contains the structural unit derived from the (meth)acrylic acid ester monomer or its derivative at 99% by mass or less, particularly preferably 95% by mass or less, and even more preferably 90% by mass or less.

[0074] The acrylic copolymer (a1) can be obtained by copolymerizing the above functional group-containing monomer and a (meth)acrylic acid ester monomer or its derivative by a conventional method. In addition to these monomers, dimethylacrylamide, vinyl formate, vinyl acetate, styrene, etc. may also be copolymerized.

[0075] The active energy ray-curable polymer (A) is obtained by reacting the acrylic copolymer (a1) having the above functional group-containing monomer unit with an unsaturated group-containing compound (a2) having a functional group that binds to the functional group.

[0076] The functional group of the unsaturated group-containing compound (a2) can be appropriately selected according to the type of the functional group of the functional group-containing monomer unit of the acrylic copolymer (a1). For example, when the functional group of the acrylic copolymer (a1) is a hydroxy group, an amino group or a substituted amino group, the functional group of the unsaturated group-containing compound (a2) is preferably an isocyanate group or an epoxy group. When the functional group of the acrylic copolymer (a1) is an epoxy group, the functional group of the unsaturated group-containing compound (a2) is preferably an amino group, a carboxy group or an aziridinyl group.

[0077] In addition, the unsaturated group-containing compound (a2) contains at least 1, preferably 1 to 6, 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, meta-isopropenyl-α,α-dimethylbenzyl isocyanate, methacryloyl isocyanate, allyl isocyanate, 1,1-(bisacryloyloxymethyl)ethyl isocyanate; acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with hydroxyethyl (meth)acrylate; acryloyl monoisocyanate compounds obtained by reacting a diisocyanate compound or a polyisocyanate compound with a polyol compound and hydroxyethyl (meth)acrylate; glycidyl (meth)acrylate; (meth)acrylic acid, 2-(1-aziridinyl)ethyl (meth)acrylate, 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline, and the like.

[0078] The unsaturated group-containing compound (a2) is preferably used in a proportion of 50 mol% or more, particularly preferably 60 mol% or more, more preferably 70 mol% or more, based on the number of moles of the functional group-containing monomer of the acrylic copolymer (a1). Further, the unsaturated group-containing compound (a2) is preferably used in a proportion of 95 mol% or less, particularly preferably 93 mol% or less, more preferably 90 mol% or less, based on the number of moles of the functional group-containing monomer of the acrylic copolymer (a1).

[0079] In the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2), the temperature, pressure, solvent, time, presence or absence of a catalyst, and type of catalyst can be appropriately selected according to the combination of the functional groups of the acrylic copolymer (a1) and the functional groups of the unsaturated group-containing compound (a2). As a result, the functional groups present in the acrylic copolymer (a1) react with the functional groups in the unsaturated group-containing compound (a2), and the unsaturated groups are introduced into the side chains in the acrylic copolymer (a1), obtaining the active energy ray-curable polymer (A).

[0080] In the adhesive in this embodiment, it is preferable to use a tin-containing catalyst as a catalyst for promoting the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2). By using a tin-containing catalyst, the reaction between the acrylic copolymer (a1) and the unsaturated group-containing compound (a2) proceeds effectively, making it easy to form an adhesive having desired performance, and also making it easy to adjust the tin atom content in the obtained adhesive layer to the above-mentioned range.

[0081] Examples of the above tin-containing catalysts include organotin compounds such as dibutyltin dilaurate, trimethyltin hydroxide, tetra-n-butyltin, organotin acid compounds such as tin octenoate, tin octylate, and tin salts such as stannous chloride and stannic chloride. Among them, dibutyltin dilaurate is preferable. These may be used alone or in combination of two or more.

[0082] The blending amount of the above tin-containing catalyst is preferably 0.010% by mass or more, particularly preferably 0.015% by mass or more, and even more preferably 0.02% by mass or more, based on the total amount of the monomers constituting the acrylic copolymer (a1). Also, the blending amount is preferably 0.12% by mass or less, particularly preferably 0.10% by mass or less, and even more preferably 0.08% by mass or less, based on the total amount of the monomers constituting the acrylic copolymer (a1). When the blending amount of the tin-containing catalyst is within the above range, while enabling the favorable formation of the active energy ray-curable polymer (A), it becomes easy to adjust the content of tin atoms in the pressure-sensitive adhesive layer to the range described above.

[0083] As described above, the weight average molecular weight (Mw) of the active energy ray-curable polymer (A) obtained is preferably 10,000 or more, particularly preferably 150,000 or more, and even more preferably 200,000 or more. Also, the weight average molecular weight (Mw) is preferably 1,500,000 or less, particularly preferably 1,000,000 or less.

[0084] Even when the active energy ray-curable pressure-sensitive adhesive contains a polymer having active energy ray-curability such as the active energy ray-curable polymer (A) as a main component, the active energy ray-curable pressure-sensitive adhesive may further contain an active energy ray-curable monomer and / or oligomer (B).

[0085] As the active energy ray-curable monomer and / or oligomer (B), for example, esters of polyhydric alcohols and (meth)acrylic acid can be used.

[0086] Examples of such active energy ray-curable monomers and / or oligomers (B) include monofunctional acrylic acid esters such as cyclohexyl (meth)acrylate and isobornyl (meth)acrylate, and polyfunctional acrylic acid esters such as trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and dimethyloltricyclodecane di(meth)acrylate, as well as polyester oligo(meth)acrylate and polyurethane oligo(meth)acrylate.

[0087] When blending an active energy ray-curable monomer and / or oligomer (B) with the active energy ray-curable polymer (A), the content of the active energy ray-curable monomer and / or oligomer (B) in the active energy ray-curable pressure-sensitive adhesive is preferably more than 0 parts by mass, particularly preferably 60 parts by mass or more, based on 100 parts by mass of the active energy ray-curable polymer (A). Also, the content is preferably 250 parts by mass or less, particularly preferably 200 parts by mass or less, based on 100 parts by mass of the active energy ray-curable polymer (A).

[0088] Here, when using ultraviolet rays as the active energy rays for curing the active energy ray-curable pressure-sensitive adhesive, it is preferable to add a photopolymerization initiator (C). By using this photopolymerization initiator (C), the polymerization curing time and the light irradiation amount can be reduced.

[0089] 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, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloroanthraquinone, (2,4,6-trimethylbenzyl diphenyl)phosphine oxide, 2-benzothiazole-N,N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, 2,2-dimethoxy-1,2-diphenylethane-1-one, and the like. These may be used alone or in combination of two or more.

[0090] The photoinitiator (C) is preferably used in an amount of 0.1 part by mass or more, particularly 0.5 part by mass or more, based on 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, the total amount of the active energy ray-curable polymer (A) and the active energy ray-curable monomer and / or oligomer (B) is 100 parts by mass). Further, the photoinitiator (C) is preferably used in an amount of 10 parts by mass or less, particularly 6 parts by mass or less, based on 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, the total amount of the active energy ray-curable polymer (A) and the active energy ray-curable monomer and / or oligomer (B) is 100 parts by mass).

[0091] In the active energy ray-curable pressure-sensitive adhesive, other components may be appropriately blended in addition to the above components. Examples of the other components include a non-active energy ray-curable polymer component or oligomer component (D), a crosslinking agent (E), and the like.

[0092] Examples of the non-active energy ray-curable polymer component or oligomer component (D) include polyacrylate ester, polyester, polyurethane, polycarbonate, polyolefin, etc., and a polymer or oligomer having a weight average molecular weight (Mw) of 3,000 to 2.5 million is preferred. By blending the component (D) into the active energy ray-curable pressure-sensitive adhesive, the tackiness and peelability before curing, the strength after curing, the adhesiveness to other layers, the storage stability, etc. can be improved. The blending amount of the component (D) is not particularly limited and is appropriately determined in the range of more than 0 part by mass and 50 parts by mass or less based on 100 parts by mass of the active energy ray-curable polymer (A).

[0093] As the crosslinking agent (E), a polyfunctional compound having reactivity with a functional group possessed by the active energy ray-curable polymer (A) or the like can be used. Examples of such polyfunctional compounds include isocyanate compounds, epoxy compounds, amine compounds, melamine compounds, aziridine compounds, hydrazine compounds, aldehyde compounds, oxazoline compounds, metal alkoxide compounds, metal chelate compounds, metal salts, ammonium salts, reactive phenolic resins, and the like. Among these, isocyanate-based compounds are preferred from the viewpoint of easily improving the adhesion of the pressure-sensitive adhesive layer to the substrate, and particularly, hexamethylene diisocyanate (HMDI) compounds are preferred.

[0094] The blending amount of the crosslinking agent (E) is preferably 0.01 part by mass or more, particularly preferably 0.03 part by mass or more, and more preferably 0.04 part by mass or more with respect to 100 parts by mass of the active energy ray-curable polymer (A). Also, the blending amount of the crosslinking agent (E) is preferably 8 parts by mass or less, particularly preferably 5 parts by mass or less, and more preferably 3.5 parts by mass or less with respect to 100 parts by mass of the active energy ray-curable polymer (A).

[0095] Next, the case where the active energy ray-curable pressure-sensitive adhesive is mainly composed of a mixture of a non-active energy ray-curable polymer component and a monomer and / or oligomer having at least one or more active energy ray-curable groups will be described below.

[0096] As the non-active energy ray-curable polymer component, for example, components similar to the above-described acrylic copolymer (a1) can be used.

[0097] As the monomer and / or oligomer having at least one or more active energy ray-curable groups, the same ones as the aforementioned component (B) can be selected. The blending ratio of the non-active energy ray-curable polymer component and the monomer and / or oligomer having at least one or more active energy ray-curable groups is preferably 1 part by mass or more, particularly preferably 60 parts by mass or more, of the monomer and / or oligomer having at least one or more active energy ray-curable groups with respect to 100 parts by mass of the non-active energy ray-curable polymer component. Also, the blending ratio is preferably 200 parts by mass or less, particularly preferably 160 parts by mass or less, of the monomer and / or oligomer having at least one or more active energy ray-curable groups with respect to 100 parts by mass of the non-active energy ray-curable polymer component.

[0098] Also in this case, similarly to the above, a photopolymerization initiator (C) and a crosslinking agent (E) can be appropriately blended.

[0099] Although the thickness of the adhesive layer can be appropriately set according to the method in which the work processing sheet is used, it is usually preferably 3 μm or more, particularly preferably 5 μm or more. Also, the thickness is preferably 50 μm or less, particularly preferably 40 μm or less.

[0100] (3) Release sheet In the sheet for workpiece processing according to this embodiment, a release sheet may be laminated on the adhesive surface of the adhesive layer for the purpose of protecting the surface until the adhesive surface is attached to the workpiece. The configuration of the release sheet is arbitrary, and an example is a plastic film subjected to a release treatment with 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 and polyethylene. As the release agent, silicone-based, fluorine-based, long-chain alkyl-based, etc. can be used, and among these, the silicone-based which can obtain inexpensive and stable performance is preferable. There is no particular limitation on the thickness of the release sheet, but it is usually 20 μm or more and 250 μm or less.

[0101] (4) Others In the sheet for workpiece processing according to this embodiment, an adhesive layer may be laminated on the surface of the adhesive layer opposite to the base material. In this case, the sheet for workpiece processing according to this embodiment can be used as a dicing die bonding sheet. In the sheet, a workpiece is attached to the surface of the adhesive layer opposite to the adhesive layer, and the adhesive layer is diced together with the workpiece, whereby a chip with the fragmented adhesive layers laminated thereon can be obtained. The chip can be easily fixed to the object on which the chip is mounted by the fragmented adhesive layers. As the material constituting the above-described adhesive layer, it is preferable to use those containing a thermoplastic resin and a low-molecular-weight thermosetting adhesive component, those containing a B-stage (semi-cured state) thermosetting adhesive component, and the like.

[0102] In addition, in the sheet for work processing according to the present embodiment, a protective film forming layer may be laminated on the adhesive surface of the adhesive layer. In this case, the sheet for work processing according to the present embodiment can be used as a sheet for forming a protective film and dicing. In such a sheet, a work is attached to the surface of the protective film forming layer opposite to the adhesive layer, and the protective film forming layer is diced together with the work, whereby chips with the fragmented protective film forming layers laminated thereon can be obtained. As the work, it is preferable to use one having a circuit formed on one side. In this case, usually, the protective film forming layer is laminated on the surface opposite to the surface on which the circuit is formed. The fragmented protective film forming layer can be cured at a predetermined timing to form a protective film having sufficient durability on the chip. The protective film forming layer is preferably made of an uncured curable adhesive.

[0103] 2. Physical properties of the sheet for work processing In the sheet for work processing according to the present embodiment, the surface resistivity of the surface (adhesive surface) on the side opposite to the base material in the adhesive layer is 1×10 13 Ω / □ or less, preferably 1×10 10 Ω / □ or less, more preferably 1×10 6 Ω / □ or less. By the adhesive surface exhibiting the above-described surface resistivity, the sheet for work processing is likely to exhibit excellent antistatic properties. Note that the lower limit value of the above surface resistivity is not particularly limited, and may be, for example, 1×10 4 Ω / □ or more, particularly 1×10 5 Ω / □ or more. The above surface resistivity is measured at an applied voltage of 100 V using a device such as a DIGITAL ELECTROMETER (manufactured by ADVANTEST).

[0104] 3. Manufacturing method of the sheet for work processing The manufacturing method of the sheet for work processing according to this embodiment is not particularly limited. For example, after forming an adhesive layer on a release sheet, it is preferable to obtain the sheet for work processing by laminating one side of a base material on the surface of the adhesive layer opposite to the release sheet. When using a base material 11b provided with an organic conductive film 112 only on one side of the base film 111, the adhesive layer 12 may be laminated on either surface of the base material 11b.

[0105] The formation of the above-mentioned adhesive layer can be performed by a known method. For example, an adhesive composition for forming the adhesive layer and, if desired, a coating solution further containing a solvent or a dispersion medium are prepared. Then, the coating solution is applied to the surface of the release sheet having releasability (hereinafter sometimes referred to as the "release surface"). Subsequently, the obtained coating film is dried to form an adhesive layer.

[0106] The application of the above-mentioned coating solution can be performed by a known method, for example, by a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc. The properties of the coating solution are not particularly limited as long as it can be applied. In some cases, the components for forming the adhesive layer are contained as a solute, and in other cases, as a disperse phase. Also, the release sheet may be peeled off as a process material, or may protect the adhesive layer until it is attached to the adherend.

[0107] When the adhesive composition for forming the adhesive layer contains the above-mentioned cross-linking agent, by changing the drying conditions (temperature, time, etc.) or by providing a separate heat treatment, the cross-linking reaction between the polymer component in the coating film and the cross-linking agent is advanced, and it is preferable to form a cross-linked structure with a desired density of existence in the adhesive layer. Further, in order to sufficiently advance the above-mentioned cross-linking reaction, after laminating the adhesive layer and the base material, curing may be performed, for example, by leaving it standing in an environment of 23°C and a relative humidity of 50% for several days.

[0108] 4. Method of using the sheet for work processing The sheet for workpiece processing according to this embodiment can be used for processing workpieces. That is, after attaching the adhesive surface of the sheet for workpiece processing according to this embodiment to the workpiece, the workpiece can be processed on the sheet for workpiece processing. Examples of the processing at this time include back grinding of semiconductor wafers, glass plates, etc., dicing of semiconductor wafers, glass plates, etc., expansion of semiconductor chips, glass chips, etc., and pickup of semiconductor chips, glass chips, etc.

[0109] Here, when the sheet for workpiece processing according to this embodiment includes the base materials 11a, 11b provided with the organic conductive film 112 or the base material 11c containing an antistatic agent, the charging effect during the conveyance or use of the sheets for workpiece processing 1A, 1B, 1C is effectively suppressed. As a result, damage to the workpiece and malfunction of the apparatus for performing the processing can be effectively suppressed.

[0110] After the processing of the workpiece on the sheet for workpiece processing is completed, the sheet for workpiece processing and the workpiece can be separated. For example, a semiconductor wafer or a glass plate as a workpiece is diced on the sheet for workpiece processing to be separated into a plurality of semiconductor chips, and then, if necessary, the sheet for workpiece processing is expanded, and then the semiconductor chips or the glass chips are individually picked up from the sheet for workpiece processing.

[0111] In addition, when the sheet for workpiece processing according to this embodiment includes the above-described adhesive layer, the sheet for workpiece processing can be used as a dicing and die bonding sheet. Further, when the sheet for workpiece processing according to this embodiment includes the above-described protective film forming layer, the sheet for workpiece processing can be used as a sheet for forming a protective film and dicing.

[0112] Here, when the adhesive layer in the present embodiment is composed of an active energy ray curable adhesive, by irradiating the adhesive layer with active energy rays to cure the adhesive layer, the adhesion between the adhesive layer and the workpiece can be reduced. Thereby, when picking up a semiconductor chip or a glass chip, it becomes possible to easily pick up the workpiece from the workpiece processing sheet.

[0113] And in the workpiece processing sheet according to the present embodiment, since the content of tin atoms in the adhesive layer is within the above-described range, when picking up the workpiece from the workpiece processing sheet, the occurrence of peeling at the interface between the base material and the adhesive layer can be suppressed. Thereby, it is possible to suppress the adhesion of the adhesive constituting the adhesive layer to the surface of the picked-up workpiece. That is, it is possible to suppress the occurrence of glue residue on the workpiece.

[0114] The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[0115] For example, other layers may be provided between the base material and the adhesive layer, or on the surface of the base material opposite to the adhesive layer.

Examples

[0116] Hereinafter, the present invention will be described more specifically by way of examples and the like, but the scope of the present invention is not limited to these examples and the like.

[0117] (1) Preparation of Adhesive Composition 52 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate, 28 parts by mass of 2-hydroxyethyl acrylate, and 0.1% of azobisisobutyronitrile (polymerization initiator) based on the total amount of these monomers were mixed in ethyl acetate, and then reacted at 60 °C for 24 hours to obtain a solution (solid content concentration: 40% by mass) containing an acrylic copolymer. When the weight average molecular weight of the acrylic copolymer was measured by the method described below, it was 500,000.

[0118] Subsequently, methyl ethyl ketone was added to the obtained solution to adjust the solid content concentration to 35% by mass. Then, 2-methacryloyloxyethyl isocyanate (MOI) in an amount corresponding to 90 mol% of 2-hydroxyethyl acrylate constituting the acrylic copolymer was added to the solution, and dibutyltin dilaurate (DBTDL) as a tin-containing catalyst was added in an amount of 0.02% by mass based on the total amount of the above-mentioned monomers. Thereafter, by reacting at 50 °C for 24 hours, a (meth)acrylate polymer (active energy ray-curable polymer) having an active energy ray-curable group introduced into the side chain was obtained. When the weight average molecular weight of the active energy ray-curable polymer was measured by the method described below, it was 500,000.

[0119] 100 parts by mass of the obtained active energy ray-curable polymer (in terms of solid content, the same hereinafter), 0.3 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name: "Irgacure 184") as a photoinitiator, and 2 parts by mass of a trimethylolpropane hexamethylene diisocyanate adduct (manufactured by Tosoh Corporation, product name: "Coronate HL") as a crosslinking agent were mixed in a solvent to obtain a coating liquid of the pressure-sensitive adhesive composition (solid content concentration: 25% by mass).

[0120] In addition, when a pressure-sensitive adhesive layer was formed using the above-mentioned coating liquid of the pressure-sensitive adhesive composition as described below, the content of tin atoms in the obtained pressure-sensitive adhesive layer was calculated to be 0.0027% by mass.

[0121] (2) Formation of the pressure-sensitive adhesive layer On the release surface of a release sheet (manufactured by Lintec Corporation, product name "SP-PET3801") formed by forming a silicone-based release agent layer on one side of a polyethylene terephthalate (PET) film with a thickness of 38 μm, the coating liquid of the above adhesive composition was applied using a comma coater and dried at 90°C for 1 minute, whereby an adhesive layer with a thickness of 5 μm was formed on the release sheet.

[0122] (3) Preparation of the substrate To an emulsion containing a polypyrrole-based conductive polymer as a conductive material obtained by emulsion polymerization of a pyrrole monomer, 2 parts by mass of a butylated melamine resin (manufactured by DIC Corporation, product name "Super Bekamin J820-60") as a binder resin was added to 100 parts by mass of the polypyrrole-based conductive polymer and mixed well to obtain a coating liquid for an organic conductive film.

[0123] One surface of an ethylene-methacrylic acid copolymer (EMAA) film with a thickness of 80 μm was subjected to corona irradiation. Then, the coating liquid for the organic conductive film obtained as described above was applied to the surface of the EMAA film subjected to corona irradiation and dried by heating to form an organic conductive film with a thickness of 50 nm. Further, the other surface of the EMAA film was also subjected to corona irradiation in the same manner as above, and then an organic conductive film with a thickness of 50 nm was formed. Thus, a substrate having organic conductive films formed on both surfaces of the EMAA film was obtained.

[0124] When the surface resistivity of both surfaces of this substrate was measured at an applied voltage of 100 V using a DIGITAL ELECTROMETER (manufactured by Advantest Corporation), it was 1.5×10 6 Ω / □. This value is extremely small compared to the general surface resistivity (1×10 15 ~1×10 16 Ω / □) of a single PET film. Therefore, it is expected that the work processing sheet obtained using the substrate prepared as described above can exhibit excellent antistatic properties.

[0125] (4) Preparation of the work processing sheet After bonding the surface of the pressure-sensitive adhesive layer formed in the above step (2) on the side opposite to the release sheet and one side of the base material obtained in the above step (3), it was stored for 1 week in an environment of 23 °C and 50%. As a result, a work processing sheet was obtained in which a release sheet, a pressure-sensitive adhesive layer, and a base material provided with organic conductive films on both sides were laminated in this order. Incidentally, the content of tin atoms in the pressure-sensitive adhesive layer of the work processing sheet is 0.0027% by mass as described above.

[0126] The weight average molecular weight (Mw) of the acrylic copolymer and the active energy ray curable polymer described above is the weight average molecular weight in terms of standard polystyrene measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC). <Measurement conditions> · Measuring device: HLC-8320 manufactured by Tosoh Corporation · GPC column (passing in the following order): manufactured by Tosoh Corporation TSK gel superH-H TSK gel superHM-H TSK gel superH2000 · Measuring solvent: Tetrahydrofuran · Measuring temperature: 40 °C

[0127] 〔Examples 2 to 6 and Comparative Examples 1 to 2〕 The composition of the active energy ray curable polymer was changed as shown in Table 1, and the amount of the tin-containing catalyst was adjusted so that the content of tin atoms in the formed pressure-sensitive adhesive layer was as described in Table 1. Otherwise, a work processing sheet was manufactured in the same manner as in Example 1.

[0128] 〔Example 7〕 A work processing sheet was manufactured in the same manner as in Example 1 except that a polypropylene film having a thickness of 80 μm was used as the base material. Incidentally, when the surface resistivity of both sides of the base material was measured at an applied voltage of 100 V using a DIGITAL ELECTROMETER (manufactured by Advantest Corporation), it was 1.8×10 15 Ω / □.

[0129] [Example 8] A work processing sheet was manufactured in the same manner as in Example 1, except that a polybutylene terephthalate film with a thickness of 80 μm was used as the base material. The surface resistivity of both sides of the base material was measured at an applied voltage of 100 V using a DIGITAL ELECTROMETER (manufactured by ADVANTEST). As a result, it was 2.4×10 15 Ω / □.

[0130] [Example 9] 100 parts by weight of polypropylene and 5 parts by weight of a polyolefin block polymer (manufactured by Sanyo Chemical Industries, Ltd., product name "Pelektron PVL"), which is a polymer type antistatic agent, were kneaded with a twin-screw kneader and then extruded into a sheet shape with an extruder to obtain an antistatic agent-containing polypropylene film with a thickness of 80 μm. A work processing sheet was manufactured in the same manner as in Example 1, except that the film was used as the base material. The surface resistivity of both sides of the base material was measured at an applied voltage of 100 V using a DIGITAL ELECTROMETER (manufactured by ADVANTEST). As a result, it was 2.3×10 10 Ω / □.

[0131] [Test Example 1] (Evaluation of Pick-up Property) Printing was performed on the #2000 polished surface of a silicon wafer (size 8 inches, thickness 350 μm) using a laser marking device (manufactured by KEYENCE, product name "MD-S9910A"). As a result, grooves with a width of approximately 50 μm and a depth of approximately 15 μm were formed in the polished surface in a cross-sectional view.

[0132] Subsequently, the adhesive surface exposed by peeling the release sheet from the work processing sheets manufactured in the examples and comparative examples was attached to the polished surface after the laser printing using a 2 kg rubber roller and left for 20 minutes.

[0133] Thereafter, the silicon wafer was diced into chips having a size of 5 mm × 5 mm under the following dicing conditions by using a dicing device (manufactured by DISCO, product name "Full Auto Dicer DF636"). Dicing Conditions Cutting method: Single cut Blade: Manufactured by DISCO, product name "SD3000-N1-90EC" Blade rotation speed: 35,000 rpm Cutting speed: 50 mm / sec Blade height: 20 μm as the depth of cut into the substrate

[0134] After dicing, ultraviolet rays were irradiated onto the adhesive layer from the surface on the substrate side of the work processing sheet (light quantity: 200 mJ / cm 2 ). Then, using a die bonder device (manufactured by Canon Machinery, product name "BESTEM-D02"), the obtained chips were picked up from the work processing sheet. At this time, when 10 chips were picked up and the push-up amount at the time of successful pickup was 300 μm or less for all chips, the pick-up property was evaluated as "〇". On the other hand, when there was a chip with a push-up amount exceeding 300 μm or a chip that could not be picked up, the pick-up property was evaluated as "×". The results are shown in Table 1.

[0135] 〔Test Example 2〕(Evaluation of adhesive residue) Regarding the work processing sheet evaluated as having a pick-up property of "○" in Test Example 1, the presence or absence of adhesion (adhesive residue) of the adhesive at the printed part in the 10 picked-up chips was confirmed. Then, the ratio (%) of the chips with confirmed adhesive residue among the 10 chips was calculated. The results are shown in Table 1.

[0136] The details of the abbreviations etc. described in Table 1 are as follows. EMAA: Ethylene-methacrylic acid copolymer PP: Polypropylene PBT: Polybutylene terephthalate 2EHA: 2-Ethylhexyl acrylate MMA: Methyl methacrylate HEA: 2-Hydroxyethyl acrylate MOI: 2-Methacryloyloxyethyl isocyanate VAc: Vinyl acetate BA: n-Butyl acrylate

[0137]

Table 1

[0138] As can be seen from Table 1, when the sheet for work processing obtained in the examples was used, no adhesive residue occurred.

Industrial applicability

[0139] The sheet for work processing of the present invention can be suitably used for processing works such as semiconductor wafers.

Explanation of reference numerals

[0140] 1A, 1B, 1C... Sheets for work processing 11a, 11b, 11c... Substrates 111, 111’... Base films 112... Organic conductive films 12... Adhesive layers

Claims

1. A workpiece processing sheet comprising a substrate and an adhesive layer laminated on one side of the substrate, The content of tin atoms in the pressure-sensitive adhesive layer is 0.002% by mass or more and 0.015% by mass or less, the surface resistivity of the surface of the substrate on which the pressure-sensitive adhesive layer is laminated is 1×10 Ω / □ or less; The workpiece processing sheet is used for dicing, The workpiece processing sheet does not have an unevenness-absorbing resin layer. A workpiece processing sheet characterized by the above.

2. 2. The workpiece processing sheet according to claim 1, wherein the adhesive layer is made of an active energy ray-curable adhesive.

3. The workpiece processing sheet according to claim 2, characterized in that the active energy ray-curable adhesive contains a polymer having active energy ray-curability and a tin-containing catalyst containing tin atoms.

4. The active energy ray-curable polymer is a (meth)acrylic acid ester polymer having an active energy ray-curable group introduced into a side chain thereof, The (meth)acrylic acid ester polymer is obtained by reacting an acrylic copolymer having a functional group-containing monomer unit with an unsaturated group-containing compound having a functional group bonded to the functional group, under the catalytic action of the tin-containing catalyst.

4. The workpiece processing sheet according to claim 3.

5. The workpiece processing sheet according to any one of claims 1 to 4, characterized in that the base material has an organic conductive film on the surface on which the adhesive layer is laminated.

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