Sheet for workpiece processing and method for manufacturing processed workpiece

Abstract

The present invention provides a workpiece processing sheet capable of satisfactorily processing a workpiece even when heat treatment is performed. The sheet for workpiece processing is provided with a base material and an adhesive layer, and a laminate in which a silicon chip having a size of 10 mm * 10 mm and a thickness of 350 [mu] m is placed on the surface of the base material on the opposite side from the adhesive layer is heated at 160 DEG C for 1 hour, and then the silicon chip is deposited on the surface of the base material in an environment of 23 DEG C, a shear force required when the silicon chip is moved on the substrate at a speed of 200 [mu] m / s by applying a force in a direction parallel to the surface to a position of 100 [mu] m from the surface of the substrate in the side surface of the silicon chip, is 0.4 N / (10 mm * 10 mm) or less, and a shear force required when the silicon chip is moved on the substrate at a speed of 200 [mu] m / s after the substrate is heated at 160 DEG C for 1 hour is less than or equal to 0.4 N / (10 mm * 10 mm). And the elongation at break measured when a tensile test is performed at a tensile speed of 200 mm / min in an environment of 23 DEG C is 400% or more.

Description

Technical Field

[0001] The present invention relates to a workpiece processing sheet that can be suitably used for processing a workpiece such as a semiconductor wafer, and a method for manufacturing a processed workpiece using the workpiece processing sheet. Background Art

[0002] The method for manufacturing a semiconductor device generally includes: a dicing step of singulating (dicing) a semiconductor wafer as a workpiece on a workpiece processing sheet to obtain a plurality of semiconductor chips; an expansion step of expanding (expanding) the workpiece processing sheet to increase the spacing between the semiconductor chips; and a pickup step of individually picking up (picking up) the semiconductor chips from the workpiece processing sheet. The workpiece processing sheet generally comprises a base material and an adhesive layer provided on one side of the base material, with the workpiece being stacked on the surface of the adhesive layer opposite the base material (hereinafter sometimes referred to as the "adhesive surface").

[0003] In recent years, there has been an increase in the number of cases where a workpiece before or after processing is subjected to heat treatment in a state where the workpiece is stacked on a workpiece processing sheet. For example, a workpiece on a workpiece processing sheet is sometimes subjected to treatments such as evaporation, sputtering, or baking for dehumidification, or a heating test is performed to confirm reliability in a high-temperature environment. This treatment accompanied by heating may cause problems such as deformation of the workpiece processing sheet due to heating or welding of the workpiece processing sheet to the device. Therefore, studies have also been conducted to give a predetermined heat resistance to the workpiece processing sheet provided for the accompanying heating process.

[0004] As an example of a heat-resistant adhesive sheet, Patent Document 1 discloses a sheet having an adhesive layer (adhesive resin layer) whose gel fraction before and after heating satisfies predetermined conditions. Furthermore, Patent Document 2 discloses a sheet having an adhesive layer having a rigidity within a specific range (the product of the nanoindentation elastic modulus at 25°C and the thickness).

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 6546378

[0008] Patent Document 2: Japanese Patent No. 6887766 Summary of the Invention

[0009] (1) Technical issues to be resolved

[0010] When the workpiece processing sheet is subjected to the above-mentioned heat treatment, the components (especially the substrate) constituting the sheet may sometimes deteriorate (for example, deform, denature, melt, etc.). If such degradation occurs, the flexibility of the workpiece processing sheet is impaired, and processing such as expansion cannot be performed. In addition, even if the degradation is temporary and the shape of the workpiece processing sheet can be maintained to a certain extent, the problem of breakage due to expansion may occur.

[0011] The present invention has been made in view of the above-mentioned actual situation, and an object of the present invention is to provide a workpiece processing sheet that can satisfactorily process a workpiece even when a heat treatment is performed.

[0012] (2) Technical solution

[0013] In order to achieve the above-mentioned purpose, first, the present invention provides a workpiece processing sheet, which is a workpiece processing sheet comprising a substrate and an adhesive layer stacked on one side of the substrate, characterized in that a stacked body formed by placing a silicon chip with a size of 10 mm×10 mm and a thickness of 350 μm on the surface of the substrate opposite to the adhesive layer is heated at 160°C for 1 hour, and then, in an environment of 23°C, a force is applied to the side of the silicon chip at a position 100 μm away from the surface of the substrate in a direction parallel to the surface, thereby making the shear force required for the silicon chip to move on the substrate at a speed of 200 μm / s less than 0.4 N / (10 mm×10 mm), and for the substrate after heating at 160°C for 1 hour, the elongation at break measured when a tensile test is performed in an environment of 23°C and at a tensile speed of 200 mm / min is 400% or more (Invention 1).

[0014] In order to achieve the above-mentioned purpose, secondly, the present invention provides a workpiece processing sheet, which is a workpiece processing sheet comprising a substrate and an adhesive layer stacked on one side of the substrate, characterized in that a stacked body formed by placing a silicon chip with a size of 10 mm×10 mm and a thickness of 350 μm on the surface of the substrate opposite to the adhesive layer is heated at 160°C for 1 hour, and then, in an environment of 23°C, a force is applied to the side of the silicon chip at a position 100 μm away from the surface of the substrate in a direction parallel to the surface, thereby making the shear force required for the silicon chip to move on the substrate at a speed of 200 μm / s less than 0.4 N / (10 mm×10 mm), and for the substrate after heating at 160°C for 1 hour, the tensile modulus measured in a tensile test at a tensile speed of 200 mm / min in an environment of 23°C is less than 350 MPa (Invention 2).

[0015] By making the workpiece processing sheet of the above inventions (Inventions 1 and 2) meet the above shear force conditions, and at the same time making the substrate meet the above elongation at break or tensile modulus conditions, even when subjected to heat treatment, the deterioration of the workpiece processing sheet (especially the substrate) can be suppressed, and the workpiece can be processed well.

[0016] In the above inventions (Inventions 1 and 2), it is preferable that the substrate is formed of a material containing a polyester resin (Invention 3).

[0017] In the above inventions (Inventions 1 to 3), it is preferred that the adhesive layer be composed of an active energy ray-curable adhesive containing a hindered amine stabilizer (Invention 4).

[0018] In the above invention (Invention 4), it is preferred that the hindered amine stabilizer is an N-alkyl hindered amine stabilizer (Invention 5).

[0019] In the above inventions (Inventions 4 and 5), the active energy ray-curable adhesive is preferably formed from an adhesive composition, and the adhesive composition contains an acrylic polymer having an active energy ray-curable group introduced into a side chain and the hindered amine stabilizer (Invention 6).

[0020] In the above inventions (Inventions 1 to 6), the workpiece processing sheet is preferably used in a workpiece processing method, and the workpiece processing method comprises: a process of heating the workpiece processing sheet in a state where the workpiece before or after processing is stacked on the side of the adhesive layer opposite to the substrate (Invention 7).

[0021] Third, the present invention provides a method for manufacturing a processed workpiece, characterized in that it comprises: a laminating process of laminating the workpiece to the surface of the adhesive layer of the workpiece processing sheet (Inventions 1 to 6) which is opposite to the substrate; a heating process of subjecting the workpiece to a treatment accompanied by heating in a state of being bonded to the workpiece processing sheet; and a processing process of processing the workpiece that has been subjected to the treatment accompanied by heating on the workpiece processing sheet (Invention 8).

[0022] (3) Beneficial effects

[0023] The workpiece processing sheet of the present invention can satisfactorily process a workpiece even when subjected to a heat treatment. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present invention will be described.

[0025] The workpiece processing sheet of the present embodiment includes a base material and an adhesive layer laminated on one surface of the base material.

[0026] Furthermore, in the workpiece processing sheet of this embodiment, a stacked body in which a silicon chip having a size of 10 mm × 10 mm and a thickness of 350 μm is placed on the surface of the above-mentioned substrate opposite to the above-mentioned adhesive layer is heated at 160°C for 1 hour, and then, in an environment of 23°C, a force is applied to the side of the above-mentioned silicon chip at a position 100 μm away from the surface of the above-mentioned substrate in a direction parallel to the above-mentioned surface, thereby making the shear force required for the above-mentioned silicon chip to move at a speed of 200 μm / s on the above-mentioned substrate less than 0.4 N / (10 mm × 10 mm).

[0027] Furthermore, in one embodiment, in the workpiece processing sheet of this embodiment, the elongation at break measured by a tensile test at 23°C and a tensile speed of 200 mm / min on the substrate heated at 160°C for 1 hour is 400% or more.

[0028] In another embodiment, in the workpiece processing sheet of this embodiment, the tensile modulus of the substrate heated at 160°C for 1 hour and measured in a tensile test at 23°C and a tensile speed of 200 mm / min is 350 MPa or less.

[0029] By making the workpiece processing sheet of this embodiment meet the above-mentioned shear force conditions and at least one of the above-mentioned elongation at break and tensile modulus, the substrate, in particular, exhibits excellent heat resistance. Thus, even when the workpiece processing sheet of this embodiment is used in a process accompanied by heating, the degradation of the workpiece processing sheet (especially the substrate) is suppressed, and the workpiece can be processed well. More specifically, it is possible to suppress the welding of the workpiece processing sheet to the processing device, etc., and to effectively expand the spacing between the chips during the expansion process.

[0030] 1. Substrate

[0031] The substrate of this embodiment is not particularly limited as long as it can meet the above-mentioned shear force conditions and at least one of the above-mentioned elongation at break and tensile modulus conditions. From the perspective of easily meeting these conditions, the substrate is preferably formed from a material containing a resin, and is particularly preferably formed from a material containing a polyester resin.

[0032] The diol component and the dicarboxylic acid component constituting the polyester resin are not particularly limited, but preferably each of them has at least one of an aromatic hydrocarbon structure (aromatic ring) and an alicyclic hydrocarbon structure (aliphatic ring).

[0033] Here, when the diol component constituting the polyester resin has an aromatic hydrocarbon structure, the dicarboxylic acid component constituting the polyester resin preferably has an alicyclic hydrocarbon structure. Furthermore, when the diol component constituting the polyester resin has an alicyclic hydrocarbon structure, the dicarboxylic acid component constituting the polyester resin preferably has an aromatic hydrocarbon structure.

[0034] Preferred examples of the aromatic hydrocarbon structure include a benzene ring, and preferred examples of the alicyclic hydrocarbon structure include a cyclohexane ring.

[0035] Specific examples of the diol component having a benzene ring include 1,2-bis(hydroxymethyl)benzene, 1,3-bis(hydroxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene, 1,2-bis(hydroxymethyl)-3,4,5,6-tetramethyl-benzene, 1,3-bis(hydroxymethyl)-2,4,5,6-tetramethyl-benzene, and 1,4-bis(hydroxymethyl)-2,3,5,6-tetramethyl-benzene. Among these, at least one of 1,3-bis(hydroxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene is preferably used, and 1,4-bis(hydroxymethyl)benzene is particularly preferably used. These may be used alone or in combination of two or more.

[0036] Specific examples of the diol component having a cyclohexane ring include 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,2-bis(hydroxymethyl)-3,4,5,6-tetramethyl-cyclohexane, 1,3-bis(hydroxymethyl)-2,4,5,6-tetramethyl-cyclohexane, and 1,4-bis(hydroxymethyl)-2,3,5,6-tetramethyl-cyclohexane. Among these, at least one of 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol is preferably used, and 1,2-cyclohexanedimethanol is particularly preferred. These may be used alone or in combination of two or more.

[0037] The polyester resin of this embodiment may also contain other diol components as diol components constituting the resin, in addition to the above-mentioned diol components having a benzene ring and the diol component having a cyclohexane ring. Examples of other diol components include aliphatic diol compounds such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, and polyalkylene glycol, and diphenyl diol compounds such as 2,2-bis(4'-β-hydroxyethoxyphenyl)propane. These diol components may be used alone or in combination of two or more.

[0038] From the viewpoints of hydrolysis resistance, cost, extrusion moldability, and crystallinity (elongation), the ratio of the diol component having a benzene ring and the diol component having a cyclohexane ring in this embodiment to all diol components constituting the polyester resin is preferably 50 mol% or more, particularly preferably 80 mol% or more, and even more preferably 95 mol% or more.

[0039] Specific examples of the dicarboxylic acid component having a benzene ring include terephthalic acid, isophthalic acid, phthalic acid, 5-tert-butylisophthalic acid, phthalic acid, 4,4-biphenyldicarboxylic acid, 4,4-biphenylsulfonedicarboxylic acid, methyl terephthalate, methyl isophthalate, methyl phthalate, 1,2-dicarboxy-3,4,5,6-tetramethyl-benzene, 1,3-dicarboxy-2,4,5,6-tetramethyl-benzene, and 1,4-dicarboxy-2,3,5,6-tetramethyl-benzene. Among them, at least one of terephthalic acid, methyl terephthalate, isophthalic acid, and methyl isophthalate is preferably used, and at least one of terephthalic acid and isophthalic acid is particularly preferably used. These may be used alone or in combination of two or more.

[0040] Specific examples of dicarboxylic acid components having a cyclohexane ring include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-dicarboxy-3,4,5,6-tetramethyl-cyclohexane, 1,3-dicarboxy-2,4,5,6-tetramethyl-cyclohexane, and 1,4-dicarboxy-2,3,5,6-tetramethyl-cyclohexane. Among them, 1,4-cyclohexanedicarboxylic acid is preferably used. These may be used alone or in combination of two or more.

[0041] The polyester resin of this embodiment may further contain other dicarboxylic acid components, in addition to the aforementioned dicarboxylic acid components having a benzene ring and the dicarboxylic acid components having a cyclohexane ring, as dicarboxylic acid components constituting the resin. Examples of other dicarboxylic acid components include naphthalene-based dicarboxylic acid compounds such as 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid, and 2,6-naphthalene dicarboxylic acid; diphenyl-based dicarboxylic acid compounds such as 4,4'-diphenyl dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, and 4,4'-diphenyl sulfone dicarboxylic acid; and aliphatic dicarboxylic acid compounds such as adipic acid and sebacic acid. These dicarboxylic acid components may be used alone or in combination of two or more.

[0042] From the viewpoints of hydrolysis resistance, cost, extrusion moldability, and crystallinity (elongation), the ratio of the dicarboxylic acid component having a benzene ring and the dicarboxylic acid component having a cyclohexane ring in this embodiment to all dicarboxylic acid components constituting the polyester resin is preferably 50 mol% or more, particularly preferably 80 mol% or more, and even more preferably 95 mol% or more.

[0043] The method for producing the polyester resin of the present embodiment is not particularly limited, and the polyester resin can be produced by a known method using a known catalyst.

[0044] The polyester resin content of all materials constituting the substrate in this embodiment is preferably 55% by mass or greater, particularly preferably 60% by mass or greater, and even more preferably 65% ​​by mass or greater. By setting this content to 55% or greater, the substrate of this embodiment tends to have better heat resistance. The upper limit of this content is not particularly limited, but is, for example, 100% or less.

[0045] The melting point of the polyester resin constituting the substrate in this embodiment is preferably 160°C or higher, particularly preferably 180°C or higher, and even more preferably 200°C or higher. By setting the melting point of the polyester resin within this range, further excellent heat resistance is easily achieved. The upper limit of the melting point of the polyester resin is not particularly limited, but may be, for example, 230°C or lower, further 280°C or lower, particularly 300°C or lower, and further preferably 320°C or lower.

[0046] The material of the substrate of this embodiment may contain other components in addition to the aforementioned polyester resin. In particular, the material may contain components used in substrate films of conventional workpiece processing sheets. Examples of such components include various additives such as flame retardants, plasticizers, lubricants, antioxidants, colorants, infrared absorbers, ultraviolet absorbers, and ion traps. The content of these additives is not particularly limited, but is preferably within a range that allows the substrate to perform its desired functions.

[0047] Commercially available resin films can be used as the substrate of this embodiment. Specific examples thereof include product names "G847," "G847H," "G855," "G855H," "G863," and "G863H" manufactured by KURABO INDUSTRIES LTD.

[0048] Furthermore, in order to improve the adhesion with the adhesive layer, the surface of the substrate of this embodiment 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.

[0049] Furthermore, the substrate of this embodiment may be provided with an oligomer sealing layer on one or both sides. The oligomer sealing layer is a layer that is used to suppress the release of low molecular weight components (oligomers) contained in the interior of the above-mentioned resin to the outside of the substrate when the substrate is heated. The above-mentioned oligomer sealing layer can be made into a cured film formed by curing an oligomer sealing layer composition containing an epoxy compound, a polyester compound, and a multifunctional amino compound. In addition, from the perspective of promoting the above-mentioned curing reaction, the oligomer sealing layer composition can further contain an acidic catalyst.

[0050] The thickness of the substrate can be appropriately set depending on the method of using the workpiece processing sheet, and is preferably 200 μm or less, particularly preferably 150 μm or less. Furthermore, the thickness of the substrate is preferably 10 μm or more, particularly preferably 25 μm or more.

[0051] 2. Adhesive layer

[0052] The adhesive constituting the adhesive layer of this embodiment is not particularly limited as long as it can exert sufficient adhesion to the adherend (especially sufficient adhesion for workpiece processing). Examples of adhesives constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and polyvinyl ether adhesives. Among them, acrylic adhesives are preferably used from the perspective of easily exerting the required adhesion.

[0053] Furthermore, the adhesive constituting the adhesive layer of this embodiment may be an adhesive that is not active energy ray-curable, but is preferably an adhesive that is active energy ray-curable (hereinafter sometimes referred to as an "active energy ray-curable adhesive"). By constituting the adhesive layer with an active energy ray-curable adhesive, the adhesive layer can be cured by irradiation with active energy rays, thereby easily reducing the adhesion of the workpiece processing sheet to the adherend. In particular, irradiation with active energy rays makes it possible to easily separate the processed workpiece from the sheet.

[0054] Furthermore, when the adhesive constituting the adhesive layer of this embodiment is an active energy ray-curable adhesive, the adhesive preferably also contains a hindered amine stabilizer. Thus, even when the workpiece processing sheet is heated (particularly when the workpiece processing sheet is heated while being stacked with the workpiece), the workpiece can be more easily separated from the sheet by subsequent irradiation with active energy rays.

[0055] As the above-mentioned active energy ray curable adhesive, it can be a polymer having active energy ray curability as the main component, or a mixture of a non-active energy ray curable polymer (a polymer not having active energy ray curability) and a monomer and / or oligomer having at least one active energy ray curable group as the main component. Further, the active energy ray curable adhesive can also be a mixture of a polymer having active energy ray curability and a monomer and / or oligomer having at least one active energy ray curable group. Among them, as the active energy ray curable adhesive of this embodiment, from the perspective of being able to suppress the adverse effects caused by excessive increase in adhesion even after heat treatment and being easy to perform good workpiece separation by lowering the adhesion using a trigger, it is preferred to use a polymer having active energy ray curability (particularly an acrylic polymer having active energy ray curability) as the main component.

[0056] The active energy ray-curable acrylic polymer is preferably an acrylic polymer having an active energy ray-curable functional group (active energy ray-curable group) introduced into a side chain (hereinafter sometimes referred to as "active energy ray-curable polymer (A)"). In this case, the active energy ray-curable adhesive of this embodiment is preferably formed from an adhesive composition containing an acrylic polymer having an active energy ray-curable group introduced into a side chain (active energy ray-curable polymer (A)).

[0057] (1) Active energy ray-curable polymer (A)

[0058] 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 of (a1).

[0059] 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 them, a monomer containing a hydroxyl group as a functional group (hydroxyl group-containing monomer) is preferably used.

[0060] Examples of the hydroxyl-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, at least one of 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate is preferably used. These hydroxyl-containing monomers may be used alone or in combination of two or more.

[0061] 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.

[0062] 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.

[0063] The (meth)acrylate polymer (a1) preferably contains 5% by mass or more of structural units derived from the above-mentioned functional group-containing monomers, and particularly preferably contains 10% by mass or more of structural units derived from the above-mentioned functional group-containing monomers. Furthermore, the (meth)acrylate polymer (a1) preferably contains 40% by mass or less of structural units derived from the above-mentioned functional group-containing monomers, and particularly preferably contains 35% by mass or less of structural units derived from the above-mentioned functional group-containing monomers. By containing the functional group-containing monomers in the (meth)acrylate polymer (a1) within the above-mentioned range, the desired active energy ray-curable polymer (A) can be easily formed.

[0064] From the perspective of easily forming 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 one having an alkyl group with 1 to 18 carbon atoms, and particularly preferably one having 1 to 8 carbon atoms.

[0065] Specific examples of the alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, lauryl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearic (meth)acrylate. These alkyl (meth)acrylates may be used alone or in combination of two or more. Among the alkyl (meth)acrylates, 2-ethylhexyl (meth)acrylate is preferred, and 2-ethylhexyl acrylate is particularly preferred.

[0066] The (meth)acrylate polymer (a1) preferably contains 20% by mass or more of structural units derived from the aforementioned alkyl (meth)acrylate, and particularly preferably contains 40% by mass or more of structural units derived from the aforementioned alkyl (meth)acrylate. Furthermore, the (meth)acrylate polymer (a1) preferably contains 95% by mass or less of structural units derived from the aforementioned alkyl (meth)acrylate, and particularly preferably contains 85% by mass or less of structural units derived from the aforementioned alkyl (meth)acrylate. By containing the alkyl (meth)acrylate in the (meth)acrylate polymer (a1) within the above-mentioned range, the workpiece processing sheet 1 readily exhibits the desired adhesive strength.

[0067] The (meth)acrylate polymer (a1) preferably further comprises a nitrogen-containing monomer as a monomer unit constituting the (meth)acrylate polymer (a1). This allows the workpiece to be more effectively held on the workpiece processing sheet during processing, and also facilitates suppressing excessive increases in adhesion to the workpiece when the workpiece processing sheet is heated. Examples of nitrogen-containing monomers include monomers having an amino group, monomers having an amide group, and monomers having a nitrogen-containing heterocyclic ring. Among these, monomers having a nitrogen-containing heterocyclic ring are preferred.

[0068] Examples of monomers having a nitrogen-containing heterocyclic ring include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl(meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, and N-vinylphthalimide. Among these, N-(meth)acryloylmorpholine is preferred, and N-acryloylmorpholine is particularly preferred.

[0069] The (meth)acrylate polymer (a1) preferably contains 3% by mass or more, particularly preferably 5% by mass or more, and further preferably 8% by mass or more of structural units derived from the above-mentioned nitrogen-containing monomers. Furthermore, the (meth)acrylate polymer (a1) preferably contains 12% by mass or less, particularly preferably 11% by mass or less, and further preferably 10% by mass or less of structural units derived from the above-mentioned nitrogen-containing monomers. By ensuring that the (meth)acrylate polymer (a1) contains the nitrogen-containing monomer within the above-mentioned range, the workpiece can be more effectively held on the workpiece processing sheet during processing, and when the workpiece processing sheet is heated, an excessive increase in adhesion to the workpiece can be easily suppressed.

[0070] 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, (meth)acrylate alkyl ester, and nitrogen atom-containing monomer.

[0071] Examples of the other monomers include: (meth)acrylates containing an alkoxyalkyl group, such as methoxymethyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxymethyl (meth)acrylate, and ethoxyethyl (meth)acrylate; (meth)acrylates having an aliphatic ring, such as cyclohexyl (meth)acrylate; (meth)acrylates having an aromatic ring, such as phenyl (meth)acrylate; non-crosslinking acrylamides, such as (meth)acrylamide and N,N-dimethyl(meth)acrylamide; non-crosslinking (meth)acrylates having a tertiary amino group, such as N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate; vinyl acetate; styrene, and the like.

[0072] The polymerization form of the (meth)acrylate polymer (a1) may be a random copolymer or a block copolymer. The polymerization method is not particularly limited, and the polymerization can be carried out by a common polymerization method, for example, a solution polymerization method.

[0073] The active energy ray-curable polymer (A) can be obtained by reacting the (meth)acrylate polymer (a1) having a functional group-containing monomer unit with the unsaturated group-containing compound (a2) having a functional group bonded to the functional group of (a1).

[0074] The functional group of the unsaturated group-containing compound (a2) can be appropriately selected depending on the type of functional group of the functional group-containing monomer unit of the (meth)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. 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.

[0075] In addition, the unsaturated group-containing compound (a2) contains at least one active energy ray-polymerizable carbon-carbon double bond in one molecule, preferably contains 1 to 6 active energy ray-polymerizable carbon-carbon double bonds, and more preferably contains 1 to 4 active energy ray-polymerizable carbon-carbon double bonds. Specific examples of such unsaturated group-containing compounds (a2) include: 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-(2-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.

[0076] 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). Furthermore, 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).

[0077] In the reaction between the (meth)acrylate polymer (a1) and the unsaturated group-containing compound (a2), the reaction temperature, pressure, solvent, reaction time, presence or absence of a catalyst, and catalyst type can be appropriately selected based on 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 in the (meth)acrylate polymer (a1) react with the functional groups in the unsaturated group-containing compound (a2), introducing unsaturated groups into the side chains of the (meth)acrylate polymer (a1), thereby producing the active energy ray-curable polymer (A).

[0078] The weight average molecular weight (Mw) of the active energy ray-curable polymer (A) obtained in this manner is preferably 10,000 or more, particularly preferably 150,000 or more, and further preferably 200,000 or more. Furthermore, the weight average molecular weight (Mw) is preferably 1.5 million or less, particularly preferably 1,000,000 or less.

[0079] (2) Hindered amine stabilizers

[0080] The adhesive composition of this embodiment also preferably contains the aforementioned hindered amine stabilizer. In this specification, a hindered amine stabilizer refers to a stabilizer having one or more amine backbones in its molecule. The hindered amine stabilizer of this embodiment is not particularly limited as long as it has such a structure.

[0081] Hindered amine stabilizers generally include the following: N-alkyl hindered amine stabilizers, which are compounds having a structure in which one or two or more alkyl groups are bonded to nitrogen atoms in a 2,2,6,6-tetramethylpiperidine skeleton; and NH-type hindered amine stabilizers, which are compounds having a structure in which one or two or more hydrogen atoms are bonded to nitrogen atoms in a 2,2,6,6-tetramethylpiperidine skeleton. In the workpiece processing sheet of this embodiment, good effects can be achieved using either of the above compounds. However, N-alkyl hindered amine stabilizers are preferred because they facilitate a good reduction in adhesion to the workpiece after heating and after irradiation with active energy rays.

[0082] Examples of the alkyl group in the N-alkyl hindered amine stabilizer include methyl, ethyl, n-propyl, isopropyl, n-butyl, n-pentyl, n-hexyl, and n-octyl. Among them, the methyl group is preferred from the viewpoint of easily reducing the adhesion to the workpiece after heating and after irradiation with active energy rays.

[0083] Specific examples of hindered amine stabilizers include p,p'-dioctyldiphenylamine, phenyl-α-naphthylamine, poly(2,2,4-trimethyl-1,2-dihydroquinoline), 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, N,N'-diphenyl-p-phenylenediamine, N,N'-di-β-naphthyl-p-phenylenediamine, N-phenyl-N'-isopropyl-p-phenylenediamine, N,N'-diallyl-p-phenylenediamine, 4,4'-(α,α-dimethylbenzyl)diphenylamine, 4-methyl-N-[4-(anilino)phenyl]benzenesulfonamide, N-phenyl-N'-(3-methacryloyloxy-2-hydroxypropyl)-p-phenylenediamine, N-(1-methylheptyl)-N'-phenyl-p-phenylenediamine, Phenylenediamine, N,N'-di-sec-butyl-p-phenylenediamine, N-phenyl-N'-1,3-dimethylbutyl-p-phenylenediamine, alkylated diphenylamine, polycondensation product of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, poly[[6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imino]-1,6-hexanediyl-[(2,2,6,6-tetramethyl-4-piperidinyl)imino]], N,N'-bis(3-aminopropyl)ethylenediamine and 2,4-bis[N-butyl-N-(1,2,2,6,6-pentamethyl-4-piperidinyl) [Amino]-6-chloro-1,3,5-triazine condensation product, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) 2-(3,5-di-tert-butyl-4-hydroxybenzyl)-2-n-butylmalonate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, tetra(1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, tetra(2,2,6,6-tetramethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, 1,2,3,4- Mixed esters of butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and 1-tridecanol, mixed esters of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 1-tridecanol, mixed esters of 1,2,3,4-butanetetracarboxylic acid with 1,2,2,6,6-pentamethyl-4-piperidinol and 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, mixed esters of 1,2,3,4-butanetetracarboxylic acid with 2,2,6,6-tetramethyl-4-piperidinol and 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane5] Undecane mixed esters, (2,2,6,6-tetramethylene-4-piperidinyl)-2-propenecarboxylate, (1,2,2,6,6-pentamethyl-4-piperidinyl)-2-propenecarboxylate, etc.

[0084] Among the above specific examples, it is preferred to use at least one of tetrakis(1,2,2,6,6-pentamethyl-4-piperidinyl)-1,2,3,4-butanetetracarboxylate as an N-alkyl hindered amine stabilizer, a mixed ester of 1,2,3,4-butanetetracarboxylic acid, 1,2,2,6,6-pentamethyl-4-piperidinol, and 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane as an N-alkyl hindered amine stabilizer, and tetrakis(2,2,6,6-tetramethyl-4-piperidinyl)-1,2,3,4-butanetetracarboxylate as an NH-type hindered amine stabilizer.

[0085] The molar mass of the hindered amine stabilizer is preferably 200 g / mol or greater, particularly preferably 600 g / mol or greater, and even more preferably 1000 g / mol or greater. Furthermore, the molar mass is preferably 10,000 g / mol or less, particularly preferably 5,000 g / mol or less, and even more preferably 3,000 g / mol or less. By setting the molar mass of the hindered amine stabilizer within the above range, it is easy to effectively reduce the adhesion to the workpiece after heating and after irradiation with active energy rays.

[0086] The content of the hindered amine stabilizer in the adhesive composition is preferably 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, and further preferably 1.0 parts by mass or more, relative to 100 parts by mass of an acrylic polymer having an active energy ray-curable group introduced into its side chain (active energy ray-curable polymer (A)). In addition, the content is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less, and further preferably 15 parts by mass or less. By setting the content of the hindered amine stabilizer within the above range, it is easy to effectively reduce the adhesion to the workpiece after heating and after irradiation with active energy rays.

[0087] (3) Cross-linking agent

[0088] The above-mentioned adhesive composition also preferably contains a cross-linking agent. By making the adhesive composition contain a cross-linking agent, in the adhesive layer, the active energy ray curable polymer (A) is cross-linked to form a good three-dimensional network structure. Thus, the cohesive force of the obtained adhesive is further increased, and it is possible to effectively suppress the generation of residual glue on the workpiece separated from the workpiece processing sheet after irradiation with active energy rays. In addition, when the adhesive composition contains a cross-linking agent, the active energy ray curable polymer (A) preferably contains the above-mentioned functional group-containing monomer as the monomer unit constituting the polymer, and particularly preferably contains a functional group-containing monomer having a high reactivity with the cross-linking agent used as the monomer unit constituting the polymer.

[0089] Examples of the cross-linking agent include isocyanate cross-linking agents, epoxy cross-linking agents, amine cross-linking agents, melamine cross-linking agents, aziridine cross-linking agents, hydrazine cross-linking agents, aldehyde cross-linking agents, oxazoline cross-linking agents, metal alkoxide cross-linking agents, metal chelate cross-linking agents, metal salt cross-linking agents, and ammonium salt cross-linking agents. These cross-linking agents can be selected based on the functional groups derived from the functional group-containing monomers in the acrylic copolymer. These cross-linking agents can be used alone or in combination of two or more.

[0090] Isocyanate crosslinking agents contain at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; biuret and isocyanurate forms thereof; and adducts thereof as reaction products with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, the isocyanurate form of hexamethylene diisocyanate is preferred, and the isocyanurate trimer of 1,6-hexamethylene diisocyanate is particularly preferred.

[0091] When the above-mentioned adhesive composition contains a cross-linking agent, relative to 100 parts by mass of active energy ray-curable polymer (A), the content of the cross-linking agent in the adhesive composition is preferably more than 0.1 parts by mass, particularly preferably more than 0.5 parts by mass, and further preferably more than 3 parts by mass. In addition, the content is preferably less than 20 parts by mass, particularly preferably less than 5 parts by mass. By making the content of the cross-linking agent more than 0.1 parts by mass, it is easy to improve the cohesion of the adhesive layer after irradiation with active energy rays, thus, it is possible to effectively suppress residual glue. In addition, by making the content of the cross-linking agent less than 20 parts by mass, the degree of cross-linking becomes appropriate, and the adhesive layer easily exerts the required adhesion.

[0092] (4) Photopolymerization initiator

[0093] The adhesive composition of this embodiment also preferably contains a photopolymerization initiator. By including a photopolymerization initiator in the adhesive composition, the polymerization curing time and the amount of light irradiation when curing the adhesive layer by irradiating active energy rays can be reduced.

[0094] Examples of photopolymerization initiators include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, benzoin dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, benzil, dibenzil, diacetyl, β-chloroanthraquinone, (2,4,6-trimethylbenzyldiphenyl)phosphine oxide, 2-benzothiazolyl N,N-diethyldithiocarbamate, oligo{2-hydroxy-2-methyl-1-[4-(1-propenyl)phenyl]propanone}, and 2,2-dimethoxy-1,2-diphenylethane-1-one. Among these, 1-hydroxycyclohexyl phenyl ketone is preferably used. The above-mentioned photopolymerization initiators may be used alone or in combination of two or more.

[0095] When the above-mentioned adhesive composition contains a photopolymerization initiator, relative to 100 parts by mass of active energy ray-curable polymer (A), the content of the photopolymerization initiator in the adhesive composition is preferably more than 0.1 parts by mass, particularly preferably more than 1 part by mass. In addition, the content is preferably less than 10 parts by mass, particularly preferably less than 5 parts by mass. By making the content of the photopolymerization initiator be the above-mentioned range, it is possible to cure the adhesive layer efficiently by irradiating active energy rays, thereby easily making the workpiece processing sheet decline well in terms of the adhesion to the adherend.

[0096] (5) Other ingredients

[0097] The adhesive composition may contain desired additives such as silane coupling agents, antistatic agents, tackifiers, antioxidants, softeners, fillers, and refractive index adjusters, as long as the effects of the workpiece processing sheet of this embodiment are not impaired.

[0098] (6) Preparation method of adhesive composition

[0099] The adhesive composition of this embodiment can be prepared by preparing an active energy ray-curable polymer (A), and mixing the obtained active energy ray-curable polymer (A) with a desired hindered amine stabilizer, a crosslinking agent, a photopolymerization initiator, and desired additives. A diluent solvent may be added as needed to obtain a coating solution of the adhesive composition.

[0100] As the above-mentioned diluting solvent, for example, aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as dichloromethane and ethylene chloride; alcohols such as methanol, ethanol, propanol, butanol, and 1-methoxy-2-propanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone; esters such as ethyl acetate and butyl acetate; cellosolve-type solvents such as ethyl cellosolve, etc. can be used.

[0101] As the concentration viscosity of the coating liquid prepared in this way, as long as it is within the scope of application, there is no particular limitation and it can be appropriately selected according to the circumstances. For example, dilution is performed in a manner such that the concentration of the adhesive composition is 10% by mass or more and 60% by mass or less. In addition, it is not necessary to add a diluting solvent when obtaining the coating liquid. If the adhesive composition is a viscosity that can be applied, a diluting solvent may not be added. At this point, the adhesive composition is a coating liquid in which the polymerization solvent of the acrylic copolymer (a1) is directly used as a diluting solvent.

[0102] (7) Thickness of adhesive layer

[0103] The thickness of the adhesive layer of this embodiment is preferably 1 μm or more, particularly preferably 3 μm or more, and more preferably 5 μm or more. By making the thickness of the adhesive layer 1 μm or more, the workpiece processing sheet is easy to exert good adhesion and easily suppress chip flying. In addition, the thickness is preferably 50 μm or less, particularly preferably 30 μm or less, and more preferably 20 μm or less. By making the thickness of the adhesive layer 50 μm or less, the workpiece is easily separated.

[0104] 3. Other components

[0105] In the workpiece processing sheet of this embodiment, before attaching the surface of the adhesive layer opposite to the substrate (adhesive surface) to the workpiece, a release sheet may be laminated on the surface for the purpose of protecting the surface.

[0106] The release sheet can be constructed in any manner, but examples thereof include plastic films treated with a release agent. Specific examples of such plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and polyolefin films such as polypropylene and polyethylene. Silicone-based, fluorine-based, long-chain alkyl, and rubber-based release agents can be used. Silicone-based release agents are preferred due to their low cost and stable performance.

[0107] The thickness of the release sheet is not particularly limited, and may be, for example, 16 μm or more and 250 μm or less.

[0108] In addition, in the workpiece processing sheet of the present embodiment, an adhesive layer can be stacked on the surface of the adhesive layer on the opposite side to the base material. At this time, the workpiece processing sheet of the present embodiment can be used as a cutting and solidifying chip. By attaching a workpiece to the surface of the adhesive layer in the sheet on the opposite side to the adhesive layer, and cutting the workpiece together with the adhesive layer, a chip stacked with a singulated adhesive layer can be obtained. The chip can be simply fixed to the object to be loaded with the chip through the singulated adhesive layer. As the material constituting the above-mentioned adhesive layer, it is preferred to use a material containing a thermoplastic resin and a low-molecular-weight thermosetting adhesive component or a material containing a B-stage (semi-cured) thermosetting adhesive component.

[0109] Furthermore, in the workpiece processing sheet of the present embodiment, a protective film forming layer can be laminated on the adhesive surface of the adhesive layer. In this case, the workpiece processing sheet of the present embodiment can be used as a protective film forming and cutting sheet. By attaching a workpiece to the surface of the protective film forming layer in such a sheet that is opposite to the adhesive layer, and cutting the workpiece together with the protective film forming layer, a chip laminated with a singulated protective film forming layer can be obtained. As the workpiece, it is preferred to use a workpiece with a circuit formed on one side. In this case, the protective film forming layer is usually laminated on the surface opposite to the surface on which the circuit is formed. By curing the singulated protective film forming layer at a specified time, a protective film with sufficient durability can be formed on the chip. Preferably, the protective film forming layer is formed of an uncured curable adhesive.

[0110] 4. Physical properties of workpiece processing sheets

[0111] As described above, in the workpiece processing sheet of this embodiment, a stacked body in which a silicon chip having a size of 10 mm × 10 mm and a thickness of 350 μm is placed on the surface of the substrate opposite to the adhesive layer is heated at 160°C for 1 hour, and then, in an environment of 23°C, a force is applied to the side of the silicon chip at a position 100 μm away from the surface of the substrate in a direction parallel to the surface, thereby making the shear force required for the silicon chip to move at a speed of 200 μm / s on the substrate less than 0.4 N / (10 mm × 10 mm).

[0112] Here, from the perspective of facilitating the workpiece processing sheet of this embodiment to exhibit superior heat resistance, the shear force is preferably 0.35 N / (10 mm × 10 mm) or less, and particularly preferably 0.32 N / (10 mm × 10 mm) or less. On the other hand, the lower limit of the shear force is preferably 0.01 N / (10 mm × 10 mm) or more. Details of the shear force measurement method are described in the test examples below.

[0113] Furthermore, as described above, in the workpiece processing sheet of this embodiment, in one embodiment, the elongation at break measured when the substrate heated at 160°C for 1 hour is subjected to a tensile test at 23°C and a tensile speed of 200 mm / min is 400% or more.

[0114] Here, from the perspective of the workpiece processing sheet of the present embodiment being easy to play more excellent heat resistance, above-mentioned elongation at break is preferably more than 500%, particularly preferably more than 800%, more preferably more than 1000%.On the other hand, the upper limit value of above-mentioned elongation at break is preferably below 1200%.In addition, in this manual, unless otherwise specified, " elongation at break " refers to the elongation at break measured in the extrusion direction (MD direction) during the molding of base material.In addition, the details of the assay method of above-mentioned elongation at break are as described in the test example described later.

[0115] Furthermore, as described above, in another embodiment of the workpiece processing sheet of this embodiment, the tensile modulus of the substrate heated at 160°C for 1 hour and measured in a tensile test at 23°C and a tensile speed of 200 mm / min is 350 MPa or less.

[0116] Here, from the workpiece processing sheet of the present embodiment, be easy to bring into play the angle of more excellent heat resistance, above-mentioned tensile modulus is preferably below 310MPa, particularly preferably below 200MPa, more preferably below 145MPa.On the other hand, the lower limit of above-mentioned tensile modulus is preferably more than 80MPa.In addition, in this manual, unless otherwise specified, otherwise " tensile modulus " refers to the tensile modulus of the extrusion direction (MD direction) measured during the molding of base material.In addition, the details of the assay method of above-mentioned tensile modulus are as described in the test example described later.

[0117] In addition, in the workpiece processing sheet of the present embodiment, for the above-mentioned base material after being heated at 160 ° C for 1 hour, the tensile stress when the tensile elongation measured when the tensile test is carried out under an environment of 23 ° C and with a tensile speed of 200 mm / min is 250% is preferably 120 MPa or less, particularly preferably 70 MPa or less, and more preferably 30 MPa or less. Thus, the workpiece processing sheet of the present embodiment is easy to exert more excellent heat resistance. On the other hand, the lower limit of the above-mentioned tensile stress is not particularly limited, for example, it can be more than 10 MPa. In addition, in this specification, unless otherwise specified, " tensile stress " refers to the tensile stress measured in the extrusion direction (MD direction) during the molding of the base material. In addition, the details of the determination method of the above-mentioned tensile stress are as described in the test example described later.

[0118] In the workpiece processing sheet of this embodiment, even when the above-mentioned heating temperature is changed from 160°C to 180°C, it is preferred to satisfy the above-mentioned conditions of shear force, elongation at break, tensile modulus and tensile stress. Furthermore, even when the above-mentioned heating temperature is changed from 160°C to 200°C, it is preferred to satisfy the above-mentioned conditions respectively.

[0119] 5. Method for manufacturing workpiece processing sheet

[0120] The method for producing the workpiece processing sheet of the present embodiment is not particularly limited, but it is preferably produced by laminating an adhesive layer on one side of a substrate.

[0121] It is possible to utilize known methods to stack an adhesive layer on the single-sided side of the substrate. For example, the adhesive layer formed on the release sheet is preferably transferred to the single-sided side of the substrate. At this time, preparation contains the adhesive composition constituting the adhesive layer and further contains a solvent or a dispersion medium as required. Coating fluid is applied to the peeling-processed surface (hereinafter, sometimes referred to as "peeling surface") of the release sheet using a die coater, a curtain coater, a spray coater, a slit coater, a blade coater, a roller coater, an applicator, etc., to form a coating film, which is dried to form an adhesive layer. As long as coating can be performed, the properties of the coating fluid are not particularly limited. There is a situation in which the composition for forming the adhesive layer is contained in the form of a solute, and there is also a situation in which the composition for forming the adhesive layer is contained in the form of a dispersion (dispersoid). The release sheet in the laminate can be peeled off as a process material, or it can be used to protect the adhesive surface of the adhesive layer before the workpiece processing sheet is attached to the adherend.

[0122] When the coating solution for forming the adhesive layer contains a crosslinking agent, the active energy ray-curable polymer (A) in the coating film can be crosslinked with the crosslinking agent by changing the drying conditions (temperature, time, etc.) or by providing a separate heat treatment, thereby forming a crosslinked structure in the adhesive layer at the desired density. To fully promote this crosslinking reaction, after laminating the adhesive layer on the substrate using the above-mentioned method, the workpiece processing sheet can be aged as follows: for example, the sheet can be left to stand for several days at 23°C and a relative humidity of 50%.

[0123] Instead of transferring the adhesive layer formed on the release sheet to one side of the substrate as described above, the adhesive layer can be formed directly on the substrate. In this case, the adhesive layer is formed by applying the above-mentioned coating liquid for forming the adhesive layer to one side of the substrate to form a coating film, and then drying the coating film.

[0124] 6. How to use the workpiece processing sheet

[0125] The workpiece processing sheet of this embodiment is suitable for processing workpieces such as semiconductor wafers. In this case, after the adhesive surface of the workpiece processing sheet of this embodiment is attached to the workpiece, the workpiece can be processed on the workpiece processing sheet. Depending on the processing, the workpiece processing sheet of this embodiment can be used as a back grinding sheet, a cutting sheet, an expansion sheet, a pick-up sheet, etc. Here, as examples of workpieces, semiconductor components such as semiconductor wafers and semiconductor packages; and glass components such as glass plates can be listed.

[0126] As described above, the workpiece processing sheet of this embodiment can suppress degradation of the base material even after being subjected to a heat treatment, and can also perform workpiece processing well. Therefore, the workpiece processing sheet of this embodiment is particularly suitable for use in a workpiece processing method, which includes a step of heating the workpiece processing sheet with the workpiece before or after processing stacked on the adhesive surface side.

[0127] For example, the workpiece processing sheet of this embodiment can be suitably used in a method for manufacturing a processed workpiece, which comprises the following steps: a laminating step of laminating the workpiece to the surface of the adhesive layer of the workpiece processing sheet that is opposite to the substrate; a heating step of subjecting the workpiece to a treatment accompanied by heating in a state in which the workpiece is bonded to the workpiece processing sheet; and a processing step of processing the workpiece that has been subjected to the treatment accompanied by heating on the workpiece processing sheet.

[0128] Furthermore, in the above-described method for manufacturing a processed workpiece, the processed workpiece obtained through the processing step can be appropriately separated from the workpiece processing sheet. For example, the above-described method preferably further comprises: a step of irradiating the adhesive layer of the workpiece processing sheet to which the processed workpiece is bonded with active energy rays to cure the adhesive layer; and a step of picking up the processed workpiece from the workpiece processing sheet having the cured adhesive layer.

[0129] The laminating step, processing step, active energy ray irradiation step, and pickup step can be performed by known methods. Furthermore, the heating step is not particularly limited. For example, the workpiece before or after processing can be subjected to treatments such as vapor deposition, sputtering, and baking, or a heating test can be performed to confirm reliability in a high-temperature environment.

[0130] The heating conditions in the above-mentioned heating process can be appropriately set according to the purpose of heating. For example, the temperature of the above-mentioned heating can be 80°C or more, in particular, 100°C or more, and further 110°C or more. In addition, the temperature can be, for example, 300°C or less, in particular, 270°C or less, and further, 200°C or less. The time of the above-mentioned heating can be, for example, 10 minutes or more, in particular, 30 minutes or more, and further, 120 minutes or more. In addition, the time can be, for example, 25 hours or less, in particular, 10 hours or less, and further, 5 hours or less. As a device for heating, a device corresponding to the purpose of heating can be used, for example, an oven, a heatable workbench, etc.

[0131] The embodiments described above are provided to facilitate understanding of the present invention and are not intended to limit the present invention. Therefore, the elements disclosed in the embodiments described above also include all design changes and equivalents within the technical scope of the present invention.

[0132] For example, another layer may be provided between the substrate and the adhesive layer, or another layer may be provided on the surface of the substrate opposite to the adhesive layer.

[0133] Example

[0134] 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.

[0135] [Example 1]

[0136] (1) Preparation of adhesive composition

[0137] 60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of N-acryloylmorpholine, and 30 parts by mass of 2-hydroxyethyl acrylate were polymerized by solution polymerization to obtain a (meth)acrylate polymer. The weight average molecular weight of the (meth)acrylate polymer was measured by the method described below and was 500,000.

[0138] The resulting (meth)acrylate polymer was reacted with methacryloyloxyethyl isocyanate (MOI) to produce an acrylic polymer having active energy ray-curable groups introduced into its side chains (active energy ray-curable polymer). The methacryloyloxyethyl isocyanate (MOI) was present in an amount equivalent to 90 mol% relative to the 2-hydroxyethyl acrylate constituting the (meth)acrylate polymer. The weight average molecular weight (Mw) of the active energy ray-curable polymer, measured by the method described below, was 500,000.

[0139] 100 parts by mass (solid content conversion, the same below) of the obtained active energy ray-curable polymer, 3.0 parts by mass of 1-hydroxycyclohexyl phenyl ketone (manufactured by IGM Resins, product name "Omnirad184") as a photopolymerization initiator, 0.9 parts by mass of an isocyanurate trimer of 1,6-hexamethylene diisocyanate (manufactured by TOSOH CORPORATION, product name "CORONATE HX") as a crosslinking agent, and 1 part by mass of tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)-1,2,3,4-butanetetracarboxylate (manufactured by ADEKA CORPORATION, product name "ADK STAB LA-52", N-methyl type hindered amine stabilizer) were mixed in a solvent to obtain a coating liquid of an adhesive composition (solid content concentration of 30% by mass).

[0140] (2) Formation of adhesive layer

[0141] The adhesive composition obtained in the above step was applied to the release surface of a release sheet (manufactured by LINTEC Corporation, product name "SP-PET381031") having a silicone release layer formed on one side of a polyethylene terephthalate film having a thickness of 38 μm. The coating liquid was then dried by heating to obtain a laminate having a 10 μm thick adhesive layer formed on the release sheet.

[0142] (3) Production of workpiece processing sheets

[0143] One surface of a polyester elastomer film (manufactured by KURABO INDUSTRIES LTD., product name "G855H", thickness: 100 μm, melting point: 208° C.) as a substrate was bonded to the adhesive layer side of the laminate obtained in the above step (2) to obtain a workpiece processing sheet.

[0144] (4) Determination of gel fraction

[0145] The weight average molecular weight (Mw) of the acrylic polymer is a weight average molecular weight in terms of standard polystyrene measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).

[0146] <Measurement conditions>

[0147] ·Measurement device: HLC-8320 manufactured by TOSOH CORPORATION

[0148] ·GPC columns (passed in the following order): manufactured by TOSOH CORPORATION

[0149] TSK gel superH-H

[0150] TSK gel superHM-H

[0151] TSK gel superH2000

[0152] ·Test solvent: tetrahydrofuran

[0153] ·Measurement temperature: 40℃

[0154] [Example 2]

[0155] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a polyester elastomer film (manufactured by KURABO INDUSTRIES LTD., product name "G863", thickness: 100 μm, melting point: 215° C.) was used as the substrate.

[0156] [Comparative Example 1]

[0157] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Corporation, product name “PET100T910E910U”, thickness: 100 μm) was used as the substrate.

[0158] [Comparative Example 2]

[0159] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a polypropylene film (manufactured by DiaPlus Film Inc., product name “PL108C”, thickness: 80 μm) was used as the substrate.

[0160] [Comparative Example 3]

[0161] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a polyethylene film (thickness: 70 μm) was used as the substrate.

[0162] [Comparative Example 4]

[0163] A workpiece processing sheet was obtained in the same manner as in Example 1 except that a polyvinyl chloride film (thickness: 80 μm) was used as the base material.

[0164] [Comparative Example 5]

[0165] A workpiece processing sheet was obtained in the same manner as in Example 1 except that an ethylene-methyl methacrylate film (thickness: 80 μm) was used as the substrate.

[0166] [Test Example 1] (Measurement of shear force)

[0167] The workpiece processing sheets produced in Examples and Comparative Examples were cut into a size of 10 cm×10 cm. The exposed surface of the adhesive layer exposed by peeling off the release sheet was attached to a glass plate of the same size to obtain a laminated body in which the substrate, adhesive layer, and glass plate were laminated in this order.

[0168] Next, a 10 mm x 10 mm, 350 μm thick silicon wafer was placed in the center of the substrate-side surface of the laminate. The silicon wafer and the laminate were then heated in an oven at 160°C, 180°C, and 200°C for one hour each. After heating, the sample was allowed to stand for one day to return to room temperature and serve as a measurement sample.

[0169] The above-mentioned measurement sample is placed on the measurement table of a bond tester (manufactured by Dager, product name "Series 4000"). At this time, it is placed in a manner that the surface of the glass plate side of the measurement sample is in contact with the measurement table. Then, a force is applied to the side of the silicon chip at a height of 100 μm from the substrate in a direction parallel to the surface of the substrate (horizontal direction), and the silicon chip is moved from the substrate at a speed of 200 μm / s. The maximum value of the force required at this time is measured and is used as the shear force (N / (10mm×10mm)). Three measurement samples are measured at each temperature, and the above-mentioned shear force is obtained as its average value. The results are shown in Table 1.

[0170] [Test Example 2] (Tensile test)

[0171] The substrates used in Examples and Comparative Examples were cut into a size of 15 mm x 90 mm, heated in an oven at 160°C, 180°C, and 200°C for 1 hour, and then allowed to stand for 1 day to return to room temperature to prepare test pieces.

[0172] For this test piece, according to JIS K7161:2014, a tensile test was carried out under the conditions of a temperature of 23 ° C and a relative humidity of 50% RH. Specifically, after setting the chuck spacing to 50 mm, the test piece was stretched at a speed of 200 mm / min using a tensile testing machine (manufactured by ORIENTEC CORPORATION, product name "TENSILON RTA-T-2M") to measure the elongation at break (%), the tensile stress (MPa) and the tensile modulus (MPa) when the tensile elongation was 250%. In addition, the extrusion direction (MD direction) during the molding of the substrate was measured. The results are shown in Table 1. In addition, for the substrate melted by the above heating, it is recorded as "unable to measure due to melting".

[0173] [Test Example 3] (Evaluation of scalability)

[0174] In Experimental Example 2, the workpiece processing sheets of Examples 1, 2, and Comparative Example 1, whose substrates were not melted, were attached to one side of a 350 μm thick silicon wafer by peeling off the release sheet. A dicing ring frame was then attached to the periphery of the exposed surface of the workpiece processing sheet (a portion not overlapping the silicon wafer). The silicon wafer was then diced using a dicing machine (manufactured by DISCO CORPORATION, product name "DFD6362") under the following conditions.

[0175] Adhesive: Silicon wafer

[0176] Wafer size: 6 inches in diameter, 350 μm in thickness

[0177] Cutting blade: Made by DISCO CORPORATION, product name "27HECC", diamond blade

[0178] Blade speed: 35,000 rpm

[0179] Cutting speed: 50mm / s

[0180] Cutting depth: Cutting to a depth of 20 μm from the surface of the substrate film

[0181] Cutting size: 8mm×8mm

[0182] Next, the diced silicon wafers were stacked on the workpiece processing sheet and heated in an oven at 160° C. for 1 hour.

[0183] Then, after returning to room temperature, the adhesive layer in the workpiece processing sheet was irradiated with ultraviolet light (illuminance: 230 mW / cm 2 , light intensity: 190mJ / cm 2 ) to solidify the adhesive layer.

[0184] The diced chips and the workpiece processing sheet with the ring frame attached were then placed in an expansion device (manufactured by JCM Co., Ltd., product name "ME-300B"), and the ring frame was pulled down at a speed of 1 mm / s until the pull-down amount reached 15 mm.

[0185] Then, the amount of pull-down (mm) at which fracture occurred was recorded. The results were used to evaluate the expandability of the workpiece processing sheet based on the following criteria. In Table 1, the case where no fracture occurred even after being pulled down to 15 mm was recorded as ">15 mm."

[0186] ○: The pull-down amount is 6 mm or more.

[0187] ×: The pull-down amount is less than 6 mm.

[0188] Cutting and expansion were performed in the same manner as above, except that the heating temperature of the oven was changed to 180° C. or 200° C., and the expandability was evaluated in the same manner as above. These results are also shown in Table 1.

[0189] [Table 1]

[0190]

[0191] As apparent from Table 1, the workpiece processing sheets obtained in Examples had a base material that did not melt even after heating and had excellent expandability.

[0192] Industrial Applicability

[0193] The workpiece processing sheet of the present invention can be suitably used for processing a workpiece such as a semiconductor wafer.

Claims

1. A workpiece processing sheet comprising a base material and an adhesive layer laminated on one side of the base material, characterized in that: A laminated body in which a silicon chip having a size of 10 mm × 10 mm and a thickness of 350 μm is placed on the surface of the substrate opposite to the adhesive layer is heated at 160° C. for 1 hour, and then, under an environment of 23° C., a force is applied in a direction parallel to the surface of the substrate at a position 100 μm from the side surface of the silicon chip, thereby causing the shear force required to move the silicon chip on the substrate at a speed of 200 μm / s to be 0.4 N / (10 mm × 10 mm) or less. The elongation at break of the substrate after heating at 160° C. for 1 hour, measured in a tensile test at a tensile speed of 200 mm / min at 23° C., is 400% or more.

2. A workpiece processing sheet comprising a base material and an adhesive layer laminated on one side of the base material, characterized in that: A laminated body in which a silicon chip having a size of 10 mm × 10 mm and a thickness of 350 μm is placed on the surface of the substrate opposite to the adhesive layer is heated at 160° C. for 1 hour, and then, under an environment of 23° C., a force is applied in a direction parallel to the surface of the substrate at a position 100 μm from the side surface of the silicon chip, thereby causing the shear force required to move the silicon chip on the substrate at a speed of 200 μm / s to be 0.4 N / (10 mm × 10 mm) or less. The tensile modulus of the substrate after heating at 160° C. for 1 hour, measured in a tensile test at a tensile speed of 200 mm / min at 23° C., was 350 MPa or less.

3. The workpiece processing sheet according to claim 1 or 2, wherein: The substrate is formed of a material containing a polyester resin.

4. The workpiece processing sheet according to claim 1 or 2, wherein: The adhesive layer is composed of an active energy ray-curable adhesive containing a hindered amine stabilizer.

5. The workpiece processing sheet according to claim 4, wherein: The hindered amine stabilizer is an N-alkyl hindered amine stabilizer.

6. The workpiece processing sheet according to claim 4, wherein: The active energy ray-curable adhesive is formed from an adhesive composition containing an acrylic polymer having an active energy ray-curable group introduced into a side chain and the hindered amine stabilizer.

7. The workpiece processing sheet according to claim 1 or 2, wherein: The workpiece processing sheet is used in a workpiece processing method including the step of heating the workpiece processing sheet in a state where the workpiece before or after processing is stacked on the surface of the adhesive layer opposite to the substrate.

8. A method for manufacturing a processed workpiece, characterized in that: It has: a step of laminating a workpiece to the surface of the adhesive layer of the workpiece processing sheet according to claim 1 or 2 that is opposite to the substrate; subjecting the workpiece in a state of being bonded to the workpiece processing sheet to a heating step involving a heating treatment; and A step of processing the workpiece subjected to the treatment involving heating on the workpiece processing sheet.

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