Protective sheet for semiconductor processing, and method for manufacturing semiconductor device

Abstract

This protective sheet for semiconductor processing comprises a base material, and an intermediate layer and a photocurable adhesive layer on one main surface of the base material, in the stated order, wherein: the intermediate layer has a storage elastic modulus (G') at 20°C of 5.0×104 to 1.0×107 Pa and a storage elastic modulus (G') at 200°C of 5.0×103 to 1.0×106 Pa; the photocurable adhesive layer has a storage elastic modulus (G') at 20°C before photocuring of 1.0×104 to 1.0×107 Pa and a storage elastic modulus (G') at 200°C before photocuring of 5.0×103 to 5.0×106 Pa; the photocurable adhesive layer is a heat-cured product of an adhesive composition containing an ethylenically-unsaturated-group-containing (meth)acrylic resin (A2), a crosslinking agent (B2), and a photopolymerization initiator (C); and the ethylenically-unsaturated-group-containing (meth)acrylic resin (A2) is an adduct of at least an epoxy-group-containing ethylenically unsaturated compound (a2-3) to a copolymer having a carboxy-group-containing ethylenically unsaturated compound (a2-2) as a raw-material monomer.

Description

Protective sheet for semiconductor processing and method for manufacturing semiconductor device

[0001] The present disclosure relates to a protective sheet for semiconductor processing and a method for manufacturing a semiconductor device.

[0002] Various protective sheets are used in semiconductor manufacturing processes. Specific examples include protective sheets (backgrinding tape) for protecting semiconductor wafers during the backgrinding (backgrinding) process, and fixing sheets (dicing tape) used during the dicing process for cutting and dividing semiconductor wafers into small element pieces. These protective sheets are removable protective sheets that are attached to the semiconductor wafer as an adherend and are peeled off from the adherend after the specified processing steps are completed.

[0003] In recent years, with the miniaturization and increasing density of electronic devices, flip-chip mounting has become mainstream as a method for mounting semiconductor elements in the smallest possible area. In flip-chip mounting, semiconductor chips (e.g., through-silicon-via (TSV) chips) with protruding electrodes (bumps) made of solder are used to bond chips together. These bumped semiconductor chips are electrically bonded to other semiconductor chips or substrates through a reflow process, in which the chips are heated to a temperature above the melting point of the solder, typically 200°C or higher, for mounting. However, when mounting semiconductor chips in communication electronic devices, electromagnetic waves generated inside the chip can cause communication problems. To prevent this, a sputtering process is sometimes performed to deposit a metal film around the periphery of the semiconductor chip as an electromagnetic wave shield. The sputtering process is typically performed at 150°C or higher. A removable protective sheet is used to protect the bump surface during the reflow and sputtering processes.

[0004] For example, Patent Document 1 describes a method for manufacturing an electronic device using an electronic component having a circuit formation surface and an adhesive laminated film having, in this order, a base layer, an irregularity-absorbing resin layer, and an adhesive resin layer.

[0005] Japanese Patent Application Laid-Open No. 2021-163785

[0006] Since bumped semiconductor chips and bumped printed wiring boards (PCBs) have large irregularities on their surfaces, protective sheets are required to accurately conform to the irregularities and adhere closely to them while performing their surface protection function, such as during processing. In addition, protective sheets are required to have high heat resistance. If the heat resistance is insufficient, problems such as outgassing from the protective sheet during high-temperature treatments such as reflow and sputtering processes, causing the sheet to float from the adherend, or leaving adhesive residue on the adherend when peeled off, can occur.

[0007] However, conventional protective sheets have not satisfied all of the above requirements. For example, in Patent Document 1, due to insufficient heat resistance, the resin in the irregularity-absorbing resin layer may leach out during the heating process, or adhesive residue may remain on the semiconductor chip when the protective sheet is peeled off.

[0008] The present disclosure provides a semiconductor processing protective sheet that can accurately conform to the surface irregularities of semiconductor devices, such as bumped semiconductor chips and bumped PCBs, through various processing steps, adheres tightly to the surface irregularities, produces little resin sagging when heated, and can be peeled off without leaving any adhesive residue after irradiation with active energy rays. In particular, the present disclosure provides a semiconductor processing protective sheet that can accurately conform to the surface irregularities and adheres tightly to the surface irregularities, produces little resin sagging when heated, and can be peeled off without leaving any adhesive residue after irradiation with active energy rays, even when the unevenness of the adherend surface has large steps (bump heights) or has undergone a high-temperature treatment process such as at 200°C. Furthermore, the present disclosure provides a method for manufacturing semiconductor devices using the semiconductor processing protective sheet.

[0009] The present disclosure includes the following aspects: [1] A protective sheet for semiconductor processing having a substrate, and an intermediate layer and a photocurable pressure-sensitive adhesive layer on one main surface of the substrate in this order, wherein the storage modulus (G') of the intermediate layer at 20°C is 5.0 × 10 ４ ~1.0 x 10 ７ Pa, and the storage modulus (G') at 200°C is 5.0 × 10 ３ ~1.0 x 10 ６ Pa, and the storage modulus (G') of the photocurable pressure-sensitive adhesive layer at 20°C before photocuring is 1.0 x 10 ４~1.0 x 10 ７ Pa, and the storage modulus (G') at 200°C before photocuring is 5.0 x 10 ３ ~5.0 x 10 ６[2] A protective sheet for semiconductor processing according to [1], wherein the photocurable pressure-sensitive adhesive layer is a thermoset product of a pressure-sensitive adhesive composition containing an ethylenically unsaturated group-containing (meth)acrylic resin (A2), a crosslinking agent (B2), and a photopolymerization initiator (C), the ethylenically unsaturated group-containing (meth)acrylic resin (A2) having a plurality of functional groups reactive with functional groups possessed by the crosslinking agent (B2), and the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is an adduct of at least an epoxy group-containing ethylenically unsaturated compound (a2-3) to a copolymer having a carboxy group-containing ethylenically unsaturated compound (a2-2) as a raw material monomer. [3] The protective sheet for semiconductor processing according to [1] or [2], wherein the ethylenically unsaturated group-containing (meth)acrylic resin (A2) has an ethylenically unsaturated group equivalent of 500 to 5,000 g / mol. [4] The protective sheet for semiconductor processing according to any one of [1] to [3], wherein the crosslinking agent (B2) is at least one selected from the group consisting of an epoxy crosslinking agent and an aziridine crosslinking agent. [5] The protective sheet for semiconductor processing according to any one of [1] to [4], wherein the intermediate layer is a thermoset product of a resin composition containing an ethylenically unsaturated group-free (meth)acrylic resin (A1) and a crosslinking agent (B1). [6] The protective sheet for semiconductor processing according to [5], wherein the monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) contains an alkyl (meth)acrylate (a1-1) and at least one selected from a hydroxy group-containing (meth)acrylate (a1-2) and a carboxy group-containing ethylenically unsaturated compound (a1-3).[7] The monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) contains at least one selected from 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate, the total content of 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate relative to the total content of the monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) is 50 mol% or more, and the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) contains at least one selected from 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate, The protective sheet for semiconductor processing according to [5] or [6], wherein the total content of 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate relative to the total content of the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is 50 mol % or more. [8] The protective sheet for semiconductor processing according to any of [1] to [7], wherein the substrate comprises at least one selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether ether ketone (PEEK), polyamide (PA), and polyimide (PI). [9] The protective sheet for semiconductor processing according to any of [1] to [8], wherein the thickness of the substrate is 5 μm to 300 μm.

[10] The protective sheet for semiconductor processing according to any one of [1] to [9], wherein the thickness of the intermediate layer is 30 to 600 μm, the thickness of the photocurable pressure-sensitive adhesive layer is 1 to 100 μm, and the thickness ratio of the intermediate layer to the photocurable pressure-sensitive adhesive layer (intermediate layer / photocurable pressure-sensitive adhesive layer) is 1 to 50.

[11] A method for manufacturing a semiconductor device having bump electrodes, comprising: a protecting step of attaching the photocurable pressure-sensitive adhesive layer surface of the protective sheet for semiconductor processing according to any one of [1] to

[10] to a surface of a semiconductor device having bump electrodes, an active energy ray irradiation step of irradiating the protective sheet for semiconductor processing with active energy rays to photocure the photocurable pressure-sensitive adhesive layer, a heating step of the semiconductor device to which the protective sheet for semiconductor processing has been attached, and a peeling step of peeling the protective sheet for semiconductor processing from the surface of the bump electrodes.

[12] The method for manufacturing a semiconductor device according to

[11] , wherein, when the height of the bump electrode is H [μm] and the total thickness of the intermediate layer and the photocurable pressure-sensitive adhesive layer is d [μm], d / H is 1.00 to 100.

[13] The method for manufacturing a semiconductor device according to

[11] or

[12] , wherein the maximum temperature reached in the heating step is 80 to 260°C.

[0010] According to the present disclosure, it is possible to provide a protective sheet for semiconductor processing that accurately conforms to the unevenness of the surface of an adherend, adheres tightly to the unevenness, produces little resin dripping during heating, and can be peeled off without leaving any adhesive residue after irradiation with active energy rays, even when the unevenness of the surface of the adherend (bump height) is large or when the adherend has undergone a high-temperature treatment process such as 200° C. Furthermore, it is possible to provide a method for manufacturing a semiconductor device using this protective sheet for semiconductor processing.

[0011] According to the present disclosure, the adhesive strength of the photocurable pressure-sensitive adhesive layer of the semiconductor processing protective sheet is reduced by irradiation with active energy rays. Specifically, the photocurable pressure-sensitive adhesive layer exhibits sufficient adhesive strength to the adherend before irradiation with active energy rays, and after irradiation with active energy rays, the unsaturated bonds in the resin form a three-dimensional crosslinked structure and harden, thereby reducing the adhesive strength and exhibiting excellent releasability, while also being able to sufficiently prevent adhesive residue on the adherend after peeling.

[0012] FIG. 1 is a schematic cross-sectional view of a protective sheet for semiconductor processing in one embodiment.

[0013] Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments described below.

[0014] In this specification, when "to" is used to describe a numerical range, the numerical values ​​at both ends are the upper and lower limits, respectively, and are included in the numerical range. When multiple upper or lower limits are listed, numerical ranges can be created using all combinations of the upper and lower limits. Similarly, when multiple numerical ranges are listed, separate numerical ranges can be created by individually selecting and combining the upper and lower limits from those numerical ranges.

[0015] In the present disclosure, (meth)acrylic means "acrylic" or "methacrylic", (meth)acrylate means "acrylate" or "methacrylate", and (meth)acryloyloxy means "acryloyloxy" or "methacryloyloxy".

[0016] In the present disclosure, the "weight average molecular weight (Mw)" refers to a value measured using gel permeation chromatography (GPC) at room temperature (23°C) under the following conditions and determined using a standard polystyrene calibration curve. Apparatus: Shodex™ GPC-101 (Resonac Inc.) Column: Shodex™ LF-804 (Resonac Inc.) Column temperature: 40°C Sample: 0.2% by mass solution of sample in tetrahydrofuran Flow rate: 1 mL / min Eluent: tetrahydrofuran Detector: RI detector

[0017] In the present disclosure, the storage modulus (G') is a value measured using a dynamic viscoelasticity measuring device (for example, Anton Paar MCR102 (Anton Paar)) under the following conditions: the measurement is performed under the conditions of a shear strain of 0.1%, a normal force of 0.3 N, a frequency of 1 Hz, a measurement temperature of 0°C to 200°C, and a heating rate of 5°C / min, and the storage moduli at 20°C and 200°C are determined, respectively.

[0018] In the present disclosure, the glass transition temperature (Tg) of a (meth)acrylic resin refers to a value obtained by converting the glass transition temperature Tga in absolute temperature, which is obtained using the FOX equation (Fox, T. G., Bull. Am. Phys. Soc., 1 (1956), p. 123) of the following formula (1), into Celsius temperature: 1 / Tga=Σi(Wi / Tgi) (1) (In formula (1), Tga is the glass transition temperature (unit: absolute temperature) of the (meth)acrylic resin. Wi is the mass proportion of each monomer i in the (meth)acrylic resin. Tgi is the glass transition temperature (unit: absolute temperature) of a homopolymer formed only from each monomer i.)

[0019] In the present disclosure, the "acid value (mg KOH / g)" is a value measured in accordance with JIS K 0070:1992.

[0020] In the present disclosure, the "hydroxyl value (mg KOH / g)" is a value measured in accordance with JIS K 0070:1992.

[0021] In the present disclosure, the "ethylenically unsaturated group equivalent (g / mol)" is a value calculated from the iodine value measured in accordance with JIS K 0070:1992.

[0022] <Semiconductor Processing Protective Sheet> In one embodiment, the semiconductor processing protective sheet comprises a substrate, an intermediate layer, and a photocurable adhesive layer, in that order, on one main surface of the substrate. Because the semiconductor processing protective sheet comprises an intermediate layer with appropriate hardness and a photocurable adhesive layer with appropriate hardness, it accurately conforms to the surface irregularities and adheres tightly to the adherend, even when the surface has large unevenness (e.g., bump height) or when subjected to a high-temperature treatment at 200°C or higher. This minimizes resin dripping during heating and allows for peeling without adhesive residue after exposure to active energy rays. Figure 1 is a schematic cross-sectional view of one embodiment of the semiconductor processing protective sheet. The semiconductor processing protective sheet 10 comprises a substrate 12, an intermediate layer 14 disposed on one main surface (the upper side in Figure 1) of the substrate 12, and a photocurable adhesive layer 16 disposed on the intermediate layer 14. The protective sheet for semiconductor processing 10 may further include a release sheet (also referred to as a separator) 18 disposed on the photocurable adhesive layer 16, if necessary. The release sheet 18 is attached to the outside of the photocurable adhesive layer for the purpose of protecting the surface of the photocurable adhesive layer (i.e., the surface attached to the adherend) until the protective sheet for semiconductor processing is ready for use. The protective sheet for semiconductor processing can be suitably used, for example, as a backgrinding tape and a dicing tape.

[0023] The protective sheet for semiconductor processing may be used as a protective sheet for semiconductor processing that is shaped according to the shape of the adherend by a punching method, etc. The protective sheet for semiconductor processing may be used as a protective sheet for semiconductor processing that is shaped into a roll by being wound up and cut.

[0024] The thickness of the protective sheet for semiconductor processing depends on the unevenness of the adherend surface (e.g., bump height), but is preferably 60 μm to 1600 μm, more preferably 100 μm to 650 μm, and even more preferably 120 μm to 550 μm. From the viewpoint of more reliably following the unevenness of the adherend surface and ensuring the processing accuracy of the adherend during the processing step, it is preferable that the thickness of the protective sheet for semiconductor processing be about 1.00 to 100 times the unevenness of the adherend surface.

[0025] The peel strength of the semiconductor processing protective sheet depends on the thickness of the semiconductor processing protective sheet, the type of adherend, and the type and order of processing steps. For example, the peel strength before active energy ray irradiation is preferably 2.0 to 25 N / 25 mm, more preferably 3.0 to 20 N / 25 mm, and even more preferably 5.0 to 15 N / 25 mm. If the peel strength before active energy ray irradiation is 2.0 N / 25 mm or more, the adhesion to the adherend before active energy ray irradiation is good. If the peel strength before active energy ray irradiation is 25 N / 25 mm or less, the peel strength during peeling can be sufficiently reduced, and adhesive residue on the adherend can be reduced.

[0026] In one embodiment, the semiconductor processing protective sheet has a reduced peel strength upon irradiation with active energy rays, allowing it to be easily peeled from an adherend without leaving any adhesive residue during the peeling process. The peel strength of the semiconductor processing protective sheet after irradiation with active energy rays varies depending on the thickness of the semiconductor processing protective sheet, the type of adherend, and the type and order of processing steps, but is preferably 0.001 to 1.0 N / 25 mm, more preferably 0.005 to 0.75 N / 25 mm, and even more preferably 0.01 to 0.5 N / 25 mm.

[0027] In the present disclosure, the peel strength refers to the value measured by a tensile test in a 180° direction at a peel rate of 300 mm / min in an environment of 23°C and 50% humidity in accordance with JIS Z 0237:2009, to measure the peel strength (N / 25 mm) of the semiconductor processing protective sheet against an adherend.

[0028] [Substrate] As the substrate, any known sheet-shaped material can be appropriately selected and used. As the substrate, a resin sheet manufactured using a transparent resin material is preferably used.

[0029] Examples of resin materials include polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); polyether ether ketone (PEEK); polyamide (PA); polyimide (PI); polyphenylene sulfide (PPS); and polytetrafluoroethylene (PTFE). Among these resin materials, at least one selected from the group consisting of PET, PEN, PEEK, PA, and PI is preferably used as the resin material, as this provides a sheet with appropriate flexibility and heat resistance. The resin materials may be used alone or in combination of two or more.

[0030] When a resin sheet is used as the substrate, the resin sheet may be a single layer or may have a multi-layer structure of two or more layers (for example, a three-layer structure). In a resin sheet having a multi-layer structure, the resin material constituting each layer may be one type or two or more types.

[0031] The thickness of the substrate can be appropriately selected depending on the type of semiconductor processing, the material of the substrate, etc., but may be, for example, 5 μm or more, 10 μm or more, or 20 μm or more, and 300 μm or less, 100 μm or less, or 60 μm or less. When the protective sheet for semiconductor processing protects a bumped semiconductor chip or bumped flexible printed circuit board (FPC) during a reflow process or sputtering process and the substrate is a resin sheet, the thickness of the substrate is preferably 5 to 300 μm, more preferably 10 to 300 μm. When the substrate thickness is 5 μm or more, the rigidity of the protective sheet for semiconductor processing is high (strong stiffness). Therefore, when the protective sheet for semiconductor processing is attached to an adherend such as a semiconductor chip or peeled from the adherend, the protective sheet for semiconductor processing tends to be less likely to wrinkle or lift. In addition, when the thickness of the substrate is 5 μm or more, the protective sheet for semiconductor processing attached to the adherend can be easily peeled from the adherend, resulting in good workability (handling). When the thickness of the substrate is 300 μm or less, the rigidity of the protective sheet for semiconductor processing is appropriate, and workability is good.

[0032] When a resin sheet is used as the substrate, the substrate can be manufactured using the above-mentioned resin material by appropriately employing a conventionally known general sheet molding method (e.g., extrusion molding, T-die molding, inflation molding, uniaxial or biaxial stretching molding, etc.).

[0033] The surface of the substrate that comes into contact with the intermediate layer may be subjected to a surface treatment to improve adhesion between the substrate and the intermediate layer, such as a corona discharge treatment, an acid treatment, an ultraviolet irradiation treatment, a plasma treatment, or application of a primer.

[0034] [Intermediate layer] The protective sheet for semiconductor processing has an intermediate layer on one main surface of the substrate. By having the intermediate layer, the protective sheet for semiconductor processing has good conformability to the step, even when the step (e.g., bump height) on the surface of the adherend is large. The storage modulus (G') of the intermediate layer at 20°C is 5.0 x 10 ４ ~1.0 x 10 ７Pa, and the storage modulus (G') at 200°C is 5.0 × 10 ３ ~1.0 x 10 ６ It is Pa.

[0035] The storage modulus (G') of the intermediate layer at 20°C is 5.0 x 10 ４ Pa or more, and ４ Pa or more is preferable, and 1.0 × 10 ５ Pa or more is more preferable, and 2.0 × 10 ５ The storage modulus (G') of the intermediate layer at 20°C is preferably 1.0 x 10 Pa or more. ７ Pa or less, and ６ Pa or less, and 6.0 × 10 ６ Pa or less is more preferable, and 1.0 × 10 ６ The storage modulus of the intermediate layer at 20° C. is preferably 5.0×10 Pa or less. Any combination of these lower and upper limits may be used. ４ When the storage modulus of the intermediate layer at 20° C. is 1.0×10 or more, stickiness of the side surfaces of the protective sheet for semiconductor processing can be suppressed. ７ When the viscosity is 100 Pa or less, the adhesion between the substrate and the photocurable pressure-sensitive adhesive layer is good.

[0036] The storage modulus (G') of the intermediate layer at 200°C is 5.0 x 10 ３ Pa or more, and ３ Pa or more is preferable, and 1.0 × 10 ４ The storage modulus (G') of the intermediate layer at 200°C is preferably 1.0 x 10 Pa or more. ６ Pa or less, and ５ Pa or less, and 2.0 × 10 ５ The storage modulus of the intermediate layer at 200°C is preferably 5.0 × 10 Pa or less. Any combination of these lower and upper limits may be used. ３ When the storage modulus of the intermediate layer at 200°C is 1.0 × 10 Pa or more, sagging of the resin during the heating step can be suppressed. ６ When the elastic modulus is 0.1 Pa or less, good conformability to the step is obtained even when the step (for example, bump height) on the surface of the adherend is large.

[0037] The thickness of the intermediate layer is preferably 30 μm or more, more preferably 50 μm or more, and even more preferably 80 μm or more. The thickness of the intermediate layer is preferably 600 μm or less, more preferably 300 μm or less, and even more preferably 200 μm or less. Any combination of these lower limit values ​​and upper limit values ​​may be used. When the thickness of the intermediate layer is 30 μm or more, the semiconductor processing protective sheet has good conformability to steps on the adherend surface. When the thickness of the intermediate layer is 600 μm or less, the processing accuracy in the processing step of the adherend is good.

[0038] The resin used in the intermediate layer is not particularly limited. The resin used in the intermediate layer preferably has a stress relaxation function during heating. Examples of resins used in the intermediate layer include (meth)acrylic resins, polyurethane resins, polyester resins, silicone resins, and rubber-based resins. Among them, it is preferable to use a (meth)acrylic resin from the viewpoints of heat resistance, versatility in molecular design, and productivity, and it is more preferable to use an ethylenically unsaturated group-free (meth)acrylic resin (A1) described below. The resin used in the intermediate layer may be used alone or in a mixture of two or more types.

[0039] The intermediate layer may be a thermoset product of a resin composition for an intermediate layer, the resin composition containing a resin having a functional group and a crosslinking agent having two or more functional groups reactive with the functional group. The resin composition for an intermediate layer is preferably a resin composition containing an ethylenically unsaturated group-free (meth)acrylic resin (A1) and a crosslinking agent (B1).

[0040] (Other Components) The resin composition for the intermediate layer may contain other components, as necessary, in addition to the resin having a functional group and the crosslinking agent having two or more functional groups capable of reacting with the functional group. Examples of other components include a tackifier, a solvent, and various additives.

[0041] <<Tackifier>> Conventionally known tackifiers can be used without any particular limitation. Examples of tackifiers include terpene-based tackifier resins, phenol-based tackifier resins, rosin-based tackifier resins, aliphatic petroleum resins, aromatic petroleum resins, copolymer-based petroleum resins, alicyclic petroleum resins, xylene resins, epoxy-based tackifier resins, polyamide-based tackifier resins, ketone-based tackifier resins, and elastomer-based tackifier resins. The tackifiers may be used alone or in combination of two or more.

[0042] When the resin composition for the intermediate layer contains a tackifier, the content thereof is preferably 30 parts by mass or less, and more preferably 5 to 20 parts by mass, per 100 parts by mass of the resin having a functional group.

[0043] <<Solvent>> A solvent can be used to dilute the resin composition for the intermediate layer in order to adjust the viscosity of the resin composition for the intermediate layer. For example, when the resin composition for the intermediate layer is to be coated, the viscosity of the resin composition for the intermediate layer can be adjusted to an appropriate viscosity using a solvent. The solvent is removed when the intermediate layer is formed.

[0044] Examples of the solvent that can be used include organic solvents such as methyl ethyl ketone, methyl isobutyl ketone, acetone, ethyl acetate, propyl acetate, tetrahydrofuran, dioxane, cyclohexanone, hexane, toluene, xylene, n-propanol, isopropyl alcohol, etc. The solvents may be used alone or in combination of two or more.

[0045] <Additives> Examples of additives include plasticizers, surface lubricants, leveling agents, softeners, antioxidants, antiaging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, benzotriazole-based light stabilizers and the like, phosphate ester-based and other flame retardants, surfactants, and antistatic agents.

[0046] [Method for Producing Resin Composition for Intermediate Layer] The resin composition for the intermediate layer can be produced by a conventionally known method, for example, by mixing and stirring a resin having a functional group, a crosslinking agent having two or more functional groups capable of reacting with the functional group, and other components, such as a tackifier, a solvent, and various additives, which are contained as needed, using a conventionally known method.

[0047] The method for mixing and stirring the components contained in the intermediate layer resin composition is not particularly limited, and the mixing and stirring can be performed using, for example, a stirring device equipped with stirring blades such as a homodisper or paddle blade.

[0048] <Resin Composition Containing (Meth)acrylic Resin (A1) and Crosslinking Agent (B1)> In one embodiment, the intermediate layer is a thermoset product of a resin composition containing an ethylenically unsaturated group-free (meth)acrylic resin (A1) and a crosslinking agent (B1). The thermoset product is a reaction product (crosslinked product) of a functional group contained in the ethylenically unsaturated group-free (meth)acrylic resin (A1) that is reactive with a functional group contained in the crosslinking agent (B1), and a functional group contained in the crosslinking agent (B1).

[0049] (Ethylenically unsaturated group-free (meth)acrylic resin (A1)) The ethylenically unsaturated group-free (meth)acrylic resin (A1) is not particularly limited as long as it has an ethylenically unsaturated group equivalent of more than 5000 g / mol, does not have an ethylenically unsaturated group, and has a plurality of functional groups reactive with the functional group possessed by the crosslinking agent (B1). In one embodiment, the ethylenically unsaturated group-free (meth)acrylic resin (A1) does not contain an ethylenically unsaturated group. Examples of functional groups reactive with the functional group possessed by the crosslinking agent (B1) include a hydroxy group, a carboxy group, an isocyanato group, a glycidyl group, an amino group, and an amide group. The ethylenically unsaturated group-free (meth)acrylic resin (A1) may be used alone or in combination of two or more. By forming the intermediate layer using the ethylenically unsaturated group-free (meth)acrylic resin (A1), the protective sheet for semiconductor processing has high heat resistance and high conformability to the irregularities of the adherend even when exposed to high temperature conditions from the step of attaching to the adherend to the processing step and the peeling step. In addition, even when the step (e.g., bump height) on the surface of the adherend becomes large, the protective sheet has good conformability to the irregularities.

[0050] Specific examples of monomers constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) include alkyl (meth)acrylates (a1-1), hydroxy group-containing (meth)acrylates (a1-2), carboxy group-containing ethylenically unsaturated compounds (a1-3), and other monomers (a1-4) described below. Preferably, the monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) contains an alkyl (meth)acrylate (a1-1) and at least one selected from the hydroxy group-containing (meth)acrylates (a1-2) and the carboxy group-containing ethylenically unsaturated compounds (a1-3). More preferably, the monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) contains at least one selected from 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate. The total content of 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate relative to the total monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) is preferably 50 mol% or more, more preferably 60 mol% or more. The upper limit of the total content of 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate relative to the total monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) is not particularly limited, but may be, for example, 99 mol%, 98 mol%, or 97 mol%. The storage modulus of the intermediate layer can be adjusted by adjusting the content of the alkyl (meth)acrylate (a1-1). Specifically, the storage modulus of the intermediate layer can be decreased by increasing the content of the alkyl (meth)acrylate (a1-1), or increased by decreasing the content of the alkyl (meth)acrylate (a1-1).

[0051] The glass transition temperature (Tg) of the ethylenically unsaturated group-free (meth)acrylic resin (A1) is preferably −80° C. to 0° C., more preferably −70° C. to −10° C., and even more preferably −60° C. to −20° C. If the glass transition temperature is −80° C. or higher, an intermediate layer with high cohesive strength can be obtained, thereby preventing resin elution during sheet molding. If the glass transition temperature is 0° C. or lower, the adhesion between the intermediate layer and the photocurable pressure-sensitive adhesive layer can be further improved.

[0052] The weight-average molecular weight of the ethylenically unsaturated group-free (meth)acrylic resin (A1) is preferably 100,000 to 2,000,000, more preferably 150,000 to 1,500,000, and even more preferably 200,000 to 1,000,000. When the weight-average molecular weight is 100,000 or more, an intermediate layer with high cohesive strength can be obtained, and resin elution during sheet formation can be prevented. When the weight-average molecular weight is 2,000,000 or less, molding and processing are easy.

[0053] As will be described later, examples of the crosslinking agent (B1) that can be used include an isocyanate crosslinking agent and an epoxy crosslinking agent.

[0054] In an embodiment in which the crosslinking agent (B1) is an isocyanate crosslinking agent, the monomer group (M1-1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) preferably contains an alkyl (meth)acrylate (a1-1) and a hydroxy group-containing (meth)acrylate (a1-2). The monomer group (M1-1) may further contain, as necessary, at least one selected from the group consisting of a carboxy group-containing ethylenically unsaturated compound (a1-3) and other monomers (a1-4).

[0055] In this embodiment, the hydroxyl value of the ethylenically unsaturated group-free (meth)acrylic resin (A1) is preferably 0.5 to 100 mgKOH / g, more preferably 1 to 50 mgKOH / g, and even more preferably 5 to 30 mgKOH / g. A hydroxyl value of 0.5 mgKOH / g or higher allows for sufficient reaction with the isocyanate crosslinking agent, resulting in an intermediate layer with high cohesive strength. A hydroxyl value of 100 mgKOH / g or lower allows the resulting resin to dissolve in commonly used organic solvents such as ethyl acetate and toluene, resulting in easy handling. By setting the hydroxyl value within the above range, the amount of crosslinking with the crosslinking agent (B1) can be adjusted to adjust the storage modulus of the intermediate layer to a desired range. Specifically, it is possible to increase the amount of crosslinking to increase the storage modulus of the intermediate layer, or decrease the amount of crosslinking to decrease the storage modulus of the intermediate layer.

[0056] In this embodiment, the content of alkyl (meth)acrylate (a1-1) in the monomer group (M1-1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) is preferably 50 to 99.5 mol%, more preferably 60 to 99 mol%, and even more preferably 70 to 98 mol%. When the content of alkyl (meth)acrylate (a1-1) is 50 mol% or more, the intermediate layer has good adhesion to the substrate and the photocurable pressure-sensitive adhesive layer. When the content of alkyl (meth)acrylate (a1-1) is 99.5 mol% or less, the content of hydroxy group-containing (meth)acrylate (a1-2) can be sufficiently ensured, thereby ensuring a sufficient amount of crosslinking with the crosslinking agent (B1), and improving the cohesive strength of the intermediate layer.

[0057] In this embodiment, the content of the hydroxy group-containing (meth)acrylate (a1-2) in the monomer group (M1-1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) is preferably 0.5 to 30 mol%, more preferably 1 to 20 mol%, and even more preferably 1.5 to 10 mol%. When the content of the hydroxy group-containing (meth)acrylate (a1-2) is 0.5 mol% or more, the amount of crosslinking with the crosslinking agent (B1) is sufficiently ensured, improving the cohesive strength of the intermediate layer. In addition, the storage modulus of the intermediate layer can be improved, thereby suppressing side stickiness of the semiconductor processing protective sheet and resin sagging during heating. When the content of the hydroxy group-containing (meth)acrylate (a1-2) is 30 mol% or less, the resulting resin is soluble in commonly used organic solvents such as ethyl acetate and toluene, making it easy to handle.

[0058] In this embodiment, when the monomer group (M1-1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) contains a carboxy group-containing ethylenically unsaturated compound (a1-3), the content thereof is preferably 0.01 to 10 mol%, more preferably 0.05 to 5 mol%, and even more preferably 0.1 to 3 mol%. When the content of the carboxy group-containing ethylenically unsaturated compound (a1-3) is 0.01 mol% or more, the cohesive strength of the intermediate layer is good. In addition, the storage modulus of the intermediate layer can be improved, thereby suppressing side stickiness of the semiconductor processing protective sheet and resin sagging during heating. When the content of the carboxy group-containing ethylenically unsaturated compound (a1-3) is 10 mol% or less, the cohesive strength of the resulting resin is not too high, resulting in good handling. Furthermore, the storage modulus of the intermediate layer is not too high, resulting in good step-following ability.

[0059] In this embodiment, when the monomer group (M1-1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) contains the other monomer (a1-4), the content thereof is preferably 0.5 to 30 mol %, more preferably 1 to 25 mol %, and even more preferably 5 to 20 mol %.

[0060] The alkyl(meth)acrylate (a1-1) is not particularly limited as long as it is a compound that does not have a functional group such as a hydroxy group or a carboxy group and has an alkyl group and a (meth)acryloyloxy group. Specific examples include linear or branched alkyl(meth)acrylates such as methyl(meth)acrylate, ethyl(meth)acrylate, n-propyl(meth)acrylate, n-butyl(meth)acrylate, tert-butyl(meth)acrylate, isobutyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, isodecyl(meth)acrylate, n-hexyl(meth)acrylate, isooctyl(meth)acrylate, and lauryl(meth)acrylate; and cyclic alkyl group-containing (meth)acrylates such as cyclohexyl(meth)acrylate, isobornyl(meth)acrylate, dicyclopentanyl(meth)acrylate, and dicyclopentanyloxyethyl(meth)acrylate. Among these, at least one selected from methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isooctyl (meth)acrylate is preferred, and at least one selected from n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate is more preferred. From the viewpoint of controlling the storage modulus of the intermediate layer and obtaining good conformability to unevenness, it is preferred to use a linear or branched alkyl (meth)acrylate in which the alkyl group has 4 to 20 carbon atoms, more preferred to use a linear or branched alkyl (meth)acrylate in which the alkyl group has 4 to 12 carbon atoms, and even more preferred to use at least one selected from n-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and lauryl (meth)acrylate. The alkyl (meth)acrylate (a1-1) may be used alone or in combination of two or more kinds.

[0061] The hydroxy group-containing (meth)acrylate (a1-2) is not particularly limited as long as it is a compound having a hydroxy group and a (meth)acryloyloxy group. Specific examples include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1,3-butanediol (meth)acrylate, 1,4-butanediol (meth)acrylate, 1,6-hexanediol (meth)acrylate, and 3-methylpentanediol (meth)acrylate. From the viewpoint of controlling the storage modulus of the intermediate layer and obtaining good unevenness conformability, a hydroxyalkyl (meth)acrylate having a hydroxy group at the end of a linear alkyl group is preferred, and at least one selected from 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate is more preferred. The hydroxy group-containing (meth)acrylate (a1-2) may be used alone or in combination of two or more kinds.

[0062] The carboxy group-containing ethylenically unsaturated compound (a1-3) is not particularly limited as long as it does not have a hydroxy group but has a carboxy group and a (meth)acryloyloxy group. By including the carboxy group-containing ethylenically unsaturated compound (a1-3) in the monomer group (M1-1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1), the carboxy group derived from the carboxy group-containing ethylenically unsaturated compound (a1-3) crosslinks with the hydroxy group derived from the hydroxy group-containing (meth)acrylate (a1-2) during intermediate layer formation, thereby improving the cohesive strength and improving the storage modulus of the intermediate layer. Additionally, since the photocurable pressure-sensitive adhesive layer also contains a carboxy group, the interlayer adhesion between the photocurable pressure-sensitive adhesive layer and the intermediate layer is also improved. Furthermore, if the crosslinking agent (B2) of the photocurable pressure-sensitive adhesive layer is an epoxy crosslinking agent, crosslinking of the carboxy groups derived from the carboxy group-containing ethylenically unsaturated compound (a1-3) by the epoxy crosslinking agent of the photocurable pressure-sensitive adhesive layer proceeds at the interface between the photocurable pressure-sensitive adhesive layer and the intermediate layer, thereby obtaining stronger interlayer adhesion, which is preferable.

[0063] Specific examples of the carboxyl group-containing ethylenically unsaturated compound (a1-3) include (meth)acrylic acid, carboxymethyl (meth)acrylate, and β-carboxyethyl (meth)acrylate. From the viewpoint of ease of polymerization, (meth)acrylic acid is preferred. The carboxyl group-containing ethylenically unsaturated compound (a1-3) may be used alone or in combination of two or more.

[0064] The other monomer (a1-4) is not particularly limited as long as it is a compound other than (a1-1) to (a1-3) and has an ethylenically unsaturated group copolymerizable therewith. Examples include alkoxyalkyl(meth)acrylates, alkoxy(poly)alkylene glycol (meth)acrylates, aromatic group-containing (meth)acrylates, fluorinated alkyl(meth)acrylates, dialkylaminoalkyl(meth)acrylates, and (meth)acrylamide compounds. The other monomer (a1-4) may be used alone or in combination of two or more.

[0065] Examples of alkoxyalkyl (meth)acrylates include ethoxyethyl (meth)acrylate, methoxyethyl (meth)acrylate, and butoxyethyl (meth)acrylate.

[0066] Examples of the alkoxy(poly)alkylene glycol (meth)acrylate include methoxydiethylene glycol (meth)acrylate, ethoxydiethylene glycol (meth)acrylate, 2-methoxyethoxyethyl (meth)acrylate, and methoxydipropylene glycol (meth)acrylate.

[0067] Examples of aromatic group-containing (meth)acrylates include benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, 3-phenoxyphenyl acrylate, 4-phenoxyphenyl acrylate, 2-biphenyl acrylate, 4-biphenyl acrylate, phenoxypolyethylene glycol (meth)acrylate, phenoxypropyl (meth)acrylate, and phenoxypolypropylene glycol (meth)acrylate.

[0068] An example of the fluorinated alkyl(meth)acrylate is octafluoropentyl(meth)acrylate.

[0069] Examples of dialkylaminoalkyl(meth)acrylates include N,N-dimethylaminoethyl(meth)acrylate and N,N-diethylaminoethyl(meth)acrylate.

[0070] Examples of the (meth)acrylamide compound include (meth)acrylamide; N-alkyl(meth)acrylamides such as N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-isopropylacrylamide, and N-hexyl(meth)acrylamide; N,N-dialkyl(meth)acrylamides such as N,N-dimethyl(meth)acrylamide and N,N-diethyl(meth)acrylamide; (meth)acryloylmorpholine; and diacetone acrylamide.

[0071] Other specific examples of the other monomer (a1-4) include acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, alkyl vinyl ethers, vinyl toluene, N-vinylpyridine, N-vinylpyrrolidone, itaconic acid dialkyl esters, fumaric acid dialkyl esters, allyl alcohol, hydroxybutyl vinyl ether, hydroxyethyl vinyl ether, 4-hydroxymethylcyclohexylmethyl vinyl ether, triethylene glycol monovinyl ether, diethylene glycol monovinyl ether, methyl vinyl ketone, allyltrimethylammonium chloride, and dimethylallyl vinyl ketone.

[0072] Among these, from the viewpoint of improving adhesion to the adherend, (meth)acrylamide compounds are preferred, N,N-dialkyl(meth)acrylamides are more preferred, and N,N-dimethyl(meth)acrylamide is even more preferred.

[0073] In an embodiment in which the crosslinking agent (B1) is an epoxy crosslinking agent, the monomer group (M1-2) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) preferably contains an alkyl (meth)acrylate (a1-1) and a carboxy group-containing ethylenically unsaturated compound (a1-3). The monomer group (M1-2) may further contain, as necessary, at least one monomer selected from the group consisting of a hydroxy group-containing (meth)acrylate (a1-2) and other monomers (a1-4).

[0074] In this embodiment, (a1-1) to (a1-4) can be the same as those described above.

[0075] In this embodiment, the content of alkyl (meth)acrylate (a1-1) in the monomer group (M1-2) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) is preferably 50 to 99.5 mol%, more preferably 60 to 99.0 mol%, and even more preferably 70 to 98.0 mol%. When the content of alkyl (meth)acrylate (a1-1) is 50 mol% or more, the intermediate layer has good adhesion to the substrate and the photocurable pressure-sensitive adhesive layer. When the content of alkyl (meth)acrylate (a1-1) is 99.5 mol% or less, the content of carboxyl group-containing ethylenically unsaturated compound (a1-3) can be sufficiently ensured, thereby ensuring a sufficient amount of crosslinking with the crosslinking agent (B1), and improving the cohesive strength of the intermediate layer.

[0076] In this embodiment, the content of the carboxy group-containing ethylenically unsaturated compound (a1-3) in the monomer group (M1-2) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) is preferably 0.01 to 30 mol%, more preferably 0.1 to 20 mol%, and even more preferably 1 to 10 mol%. When the content of the carboxy group-containing ethylenically unsaturated compound (a1-3) is 0.01 mol% or more, the cohesive strength of the intermediate layer is good. In addition, the storage modulus of the intermediate layer can be improved, thereby suppressing side stickiness of the semiconductor processing protective sheet and resin sagging during heating. When the content of the carboxy group-containing ethylenically unsaturated compound (a1-3) is 30 mol% or less, the cohesive strength of the resulting resin is not too high, resulting in good handling. Furthermore, the storage modulus of the intermediate layer is not too high, resulting in good step-following ability.

[0077] In this embodiment, the acid value of the ethylenically unsaturated group-containing (meth)acrylic resin (A1) is preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, and even more preferably 5 mgKOH / g or more. The acid value of the ethylenically unsaturated group-containing (meth)acrylic resin (A1) is preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less, and even more preferably 10 mgKOH / g or less. Any combination of these lower and upper limits may be used. When the acid value is 1 mgKOH / g or more, the intermediate layer can react sufficiently with the crosslinking agent (B1), resulting in a high cohesive strength. In addition, the crosslink density of the intermediate layer can be sufficiently ensured, and the storage modulus can be improved, thereby suppressing side stickiness of the semiconductor processing protective sheet and resin sagging during heating. When the acid value is 30 mgKOH / g or less, the cohesive strength of the resulting intermediate layer is not too high, making it easy to handle. Furthermore, the storage modulus of the intermediate layer is not too high, resulting in good step-following ability.

[0078] In this embodiment, when the monomer group (M1-2) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) includes a hydroxy group-containing (meth)acrylate (a1-2), the content thereof is preferably 0.01 to 30 mol%, more preferably 0.1 to 20 mol%, and even more preferably 0.1 to 10 mol%. When the content of the hydroxy group-containing (meth)acrylate (a1-2) is 0.01 mol% or more, a sufficient amount of crosslinking with the crosslinking agent (B1) can be ensured. In addition, the storage modulus of the intermediate layer can be improved. When the content of the hydroxy group-containing (meth)acrylate (a1-2) is 30 mol% or less, the resulting resin is soluble in commonly used organic solvents such as ethyl acetate and toluene, and therefore is easy to handle.

[0079] In this embodiment, the content of the other monomer (a1-4) in the monomer group (M1-2) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) is preferably 0.1 to 45 mol %, more preferably 0.1 to 35 mol %, and even more preferably 0.1 to 25 mol %.

[0080] (Crosslinking Agent (B1)) The crosslinking agent (B1) is not particularly limited as long as it is a compound having a plurality of functional groups capable of reacting with any of the functional groups possessed by the ethylenically unsaturated group-free (meth)acrylic resin (A1), and can be selected in accordance with the functional groups possessed by the ethylenically unsaturated group-free (meth)acrylic resin (A1). For example, when the ethylenically unsaturated group-free (meth)acrylic resin (A1) has a hydroxy group, it is preferable to use at least one selected from the group consisting of an isocyanate crosslinking agent and an epoxy crosslinking agent as the crosslinking agent (B1), and it is more preferable to use an isocyanate crosslinking agent. When the ethylenically unsaturated group-free (meth)acrylic resin (A1) has a carboxy group, it is preferable to use at least one selected from the group consisting of an isocyanate crosslinking agent, an epoxy crosslinking agent, and an aziridine crosslinking agent as the crosslinking agent (B1), and it is more preferable to use an epoxy crosslinking agent. By containing the crosslinking agent (B1) in the intermediate layer, the cohesive strength of the intermediate layer is improved, and adhesive residue can be reduced when the semiconductor processing protection sheet is peeled off from the adherend. The crosslinking agent (B1) may be used alone or in combination of two or more.

[0081] Preferred combinations of the ethylenically unsaturated group-free (meth)acrylic resin (A1) and the crosslinking agent (B1) include a combination of the ethylenically unsaturated group-free (meth)acrylic resin (A1) having a hydroxy group and an isocyanate crosslinking agent, a combination of the ethylenically unsaturated group-free (meth)acrylic resin (A1) having a carboxy group and an epoxy crosslinking agent, and a combination of the ethylenically unsaturated group-free (meth)acrylic resin (A1) having a carboxy group and an aziridine crosslinking agent, and more preferred is a combination of the ethylenically unsaturated group-free (meth)acrylic resin (A1) having a hydroxy group and an isocyanate crosslinking agent.

[0082] The isocyanate crosslinking agent is a compound having two or more isocyanate groups. Examples thereof include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hydrogenated tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, isophorone diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, an isocyanurate of hexamethylene diisocyanate, tetramethylxylylene diisocyanate, 1,5-naphthalene diisocyanate, a tolylene diisocyanate adduct of trimethylolpropane, a xylylene diisocyanate adduct of trimethylolpropane, triphenylmethane triisocyanate, and methylenebis(4-phenylmethane)triisocyanate. Among these, an isocyanurate of hexamethylene diisocyanate and an adduct of trimethylolpropane with tolylene diisocyanate are preferred. The isocyanate crosslinking agents may be used alone or in combination of two or more.

[0083] The epoxy crosslinking agent is a compound having two or more epoxy groups. Examples include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, bisphenol A-epichlorohydrin epoxy resin, N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine], ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether, and polydimethylsiloxanes modified with epoxy at both ends. The epoxy crosslinking agents may be used alone or in combination of two or more.

[0084] The aziridine crosslinking agent is a compound having two or more aziridinyl groups. Examples thereof include ethylene glycol-bis-[3-(2-aziridinyl)propionate], trimethylolpropane-tris[3-(2-aziridinyl)propionate], trimethylolpropane-tris[3-(1-aziridinyl)propionate], trimethylolpropane-tris[3-(2-methyl-1-aziridinyl)propionate], tetramethylolmethane-tris[3-(2-aziridinyl)propionate], pentaerythritol-tris[3-(1-aziridinyl)propionate], 2-methyl-1-aziridinylpropionate ... , 2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate], N,N'-diphenylmethane-4,4'-bis(1-aziridinecarboxamide), N,N'-hexamethylene-1,6-bis(1-aziridinecarboxamide), tris-2,4,6-(1-aziridinyl)-1,3,5-triazine, tris(1-aziridinyl)phosphine oxide, 2,2-bis(hydroxymethyl)butanol-tris[3-(1-aziridinyl)propionate], etc. The aziridine crosslinking agent may be used alone or in combination of two or more thereof.

[0085] The content of the crosslinking agent (B1) is preferably 0.05 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.1 to 10 parts by mass, relative to 100 parts by mass of the ethylenically unsaturated group-free (meth)acrylic resin (A1). When the content of the crosslinking agent (B1) is 0.05 parts by mass or more, a three-dimensional crosslinked structure is sufficiently formed in the intermediate layer, resulting in an intermediate layer with high heat resistance. In addition, the storage modulus of the intermediate layer can be improved, thereby suppressing side stickiness of the semiconductor processing protective sheet and resin sagging during heating. When the content of the crosslinking agent (B1) is 30 parts by mass or less, an appropriate gelation time can be ensured during sheet molding. In addition, the storage modulus of the intermediate layer is not too high, resulting in good adhesion to the substrate and the photocurable pressure-sensitive adhesive layer, and good step-following ability can be obtained even when the step (e.g., bump height) on the adherend surface is large.

[0086] [Method for producing ethylenically unsaturated group-free (meth)acrylic resin (A1)] The method for producing the ethylenically unsaturated group-free (meth)acrylic resin (A1) is not particularly limited. For example, the ethylenically unsaturated group-free (meth)acrylic resin (A1) can be obtained by copolymerizing raw material monomers using a known polymerization method. Specifically, the polymerization method can be a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, an alternating copolymerization method, or the like. Among these polymerization methods, it is preferable to use a solution polymerization method in terms of ease of reaction.

[0087] When the (meth)acrylic resin (A1) containing no ethylenically unsaturated groups is produced by solution polymerization, a radical polymerization initiator is used as needed.

[0088] The radical polymerization initiator is not particularly limited, and can be appropriately selected from known initiators. Examples of the radical polymerization initiator include azo-based polymerization initiators such as 2,2'-azobis(isobutyronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4,4-trimethylpentane), and dimethyl-2,2'-azobis(2-methylpropionate); and oil-soluble polymerization initiators such as peroxide-based polymerization initiators such as benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxybenzoate, dicumyl peroxide, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, and 1,1-bis(t-butylperoxy)cyclododecane.

[0089] The radical polymerization initiators may be used alone or in combination of two or more.

[0090] The amount of radical polymerization initiator used is preferably 0.01 to 5 parts by mass, more preferably 0.02 to 4 parts by mass, and even more preferably 0.03 to 3 parts by mass, per 100 parts by mass of raw material monomer.

[0091] The solvent used in producing the ethylenically unsaturated group-free (meth)acrylic resin (A1) by solution polymerization can be a common solvent. Examples of the solvent include esters such as ethyl acetate, propyl acetate, and butyl acetate; aromatic hydrocarbons such as toluene, xylene, and benzene; aliphatic hydrocarbons such as hexane and heptane; alicyclic hydrocarbons such as cyclohexane and methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone; glycols such as ethylene glycol, propylene glycol, and dipropylene glycol; glycol ethers such as methyl cellosolve, propylene glycol monomethyl ether, and dipropylene glycol monomethyl ether; and glycol esters such as ethylene glycol diacetate and propylene glycol monomethyl ether acetate.

[0092] The solvents may be used alone or in combination of two or more.

[0093] [Method for Producing Intermediate Layer] The method for producing an intermediate layer will be described below, taking as an example a case where an intermediate layer is produced using a resin composition containing a resin having a functional group and a crosslinking agent having two or more functional groups reactive with the functional group. When using the above resin composition, the intermediate layer can be produced, for example, by the following method. First, the resin composition is applied to a substrate, and if a solvent is contained, the composition is heated and dried to remove the solvent, thereby forming a pre-cured intermediate layer. Thereafter, a release sheet is attached to the pre-cured intermediate layer, if necessary, until immediately before laminating the photocurable pressure-sensitive adhesive layer or the pre-thermocurable photocurable pressure-sensitive adhesive layer. The pre-cured intermediate layer may be cured by heating and curing the resulting sheet in an oven or the like for a certain period of time, thereby causing a curing reaction and forming a crosslinked structure. The curing reaction may be carried out after laminating the pre-cured intermediate layer and the pre-thermocurable photocurable pressure-sensitive adhesive layer.

[0094] When using the above resin composition, the intermediate layer can also be produced by the method shown below. The resin composition is applied to a release sheet, and if a solvent is contained, the composition is heated and dried to remove the solvent, thereby forming a pre-cured intermediate layer. The release sheet having the pre-cured intermediate layer is then placed on a substrate with the surface of the pre-cured intermediate layer facing the substrate, and the intermediate layer is transferred (adhered) onto the substrate. The obtained sheet may be subjected to the above-described process to form a crosslinked structure.

[0095] The resin composition can be applied to a substrate or a release sheet by any known method, including, for example, a method using a conventional coater such as a gravure roll coater, a reverse roll coater, a kiss roll coater, a dip roll coater, a bar coater, a knife coater, a spray coater, a comma coater, or a direct coater.

[0096] The conditions for heat-drying the applied resin composition are not particularly limited, but are typically 25 to 180°C, preferably 60 to 150°C, for 1 to 20 minutes, preferably 1 to 10 minutes. Heat-drying under these conditions allows for the removal of the solvent contained in the resin composition. The reaction conditions for curing (crosslinking) the uncured intermediate layer after heat-drying are not particularly limited and can be appropriately determined depending on the type and amount of resin and crosslinking agent used. When using a resin composition containing an ethylenically unsaturated group-free (meth)acrylic resin (A1) and a crosslinking agent (B1), the curing reaction is typically performed at 25 to 100°C, preferably 30 to 80°C, for 1 to 14 days, preferably 1 to 7 days. By carrying out the curing reaction under these conditions, the ethylenically unsaturated group-free (meth)acrylic resin (A1) and the crosslinking agent (B1) are crosslinked, allowing the storage modulus of the intermediate layer to be adjusted within the desired range.

[0097] (Release Sheet (Separator)) As the release sheet, any known sheet-shaped material can be appropriately selected and used. As the release sheet, the same material as the above-mentioned resin sheet used as the substrate can be used.

[0098] The thickness of the release sheet can be appropriately selected depending on the material of the release sheet, etc. When a resin sheet is used as the release sheet, the thickness of the release sheet is preferably 5 to 300 μm, more preferably 10 to 200 μm, and even more preferably 25 to 100 μm.

[0099] The release surface of the release sheet, i.e., the surface that is placed in contact with the intermediate layer, may be subjected to a release treatment using a conventionally known release agent such as a silicone-based, long-chain alkyl-based, or fluorine-based release agent, if necessary.

[0100] [Photocurable Pressure-Sensitive Adhesive Layer] The photocurable pressure-sensitive adhesive layer is a layer composed of a thermosetting product of a pressure-sensitive adhesive composition containing an ethylenically unsaturated group-containing (meth)acrylic resin (A2), a crosslinking agent (B2), and a photopolymerization initiator (C). The thermosetting product is a reaction product (crosslinked product) of a functional group contained in the ethylenically unsaturated group-containing (meth)acrylic resin (A2), which is reactive with a functional group contained in the crosslinking agent (B2), and a functional group contained in the crosslinking agent (B2). It is not a photocured product formed by the photopolymerization initiator (C). In the photocurable pressure-sensitive adhesive layer, irradiation with active energy rays such as ultraviolet rays decomposes the photopolymerization initiator (C), causing the ethylenically unsaturated groups contained in the ethylenically unsaturated group-containing (meth)acrylic resin (A2) to initiate radical polymerization, thereby forming a further crosslinked structure (photocuring). By having a photocurable adhesive layer, the semiconductor processing protection sheet has good adhesion to the adherend without lifting even when it is subjected to various processing steps while attached to the adherend. Furthermore, after the processing steps are completed, the peel strength of the photocurable adhesive layer can be reduced by irradiation with active energy rays, allowing the adhesive layer to be peeled from the adherend without leaving any adhesive residue.

[0101] The storage modulus (G') of the photocurable pressure-sensitive adhesive layer at 20°C before photocuring is 1.0 x 10 ４ Pa or more, and ４ Pa or more is preferable, and 1.0 × 10 ５ The storage modulus (G') of the photocurable pressure-sensitive adhesive layer at 20°C before photocuring is preferably 1.0 x 10 Pa or more. ７ Pa or less, and ６ Pa or less, and 5.0 × 10６ The elastic modulus of the photocurable pressure-sensitive adhesive layer at 20°C before photocuring is preferably 1.0 x 10 Pa or less. ４ When the modulus of elasticity of the photocurable pressure-sensitive adhesive layer at 20°C before photocuring is 1.0 x 10 Pa or more, stickiness of the side surfaces of the protective sheet for semiconductor processing can be suppressed. ７ When the viscosity is 100 Pa or less, a protective sheet for semiconductor processing having good conformability to unevenness can be obtained.

[0102] The storage modulus of the photocurable pressure-sensitive adhesive layer at 200°C before photocuring was 5.0 x 10 ３ Pa or more, and ３ Pa or more is preferable, and 1.0 × 10 ４ The storage modulus of the photocurable pressure-sensitive adhesive layer at 200°C before photocuring is preferably 5.0 × 10 Pa or more. ６ Pa or less, and ６ Pa or less, and 1.0 × 10 ６ The storage modulus of the photocurable pressure-sensitive adhesive layer at 200°C before photocuring is preferably 5.0 x 10 Pa or less. ３ When the storage modulus at 200°C before photocuring of the photocurable pressure-sensitive adhesive layer is 5.0 × 10 Pa or more, resin dripping during the heating step can be prevented. ６ When the elastic modulus is 0.1 Pa or less, good conformability to the step is obtained even when the step (for example, bump height) on the surface of the adherend is large.

[0103] The thickness of the photocurable pressure-sensitive adhesive layer is preferably 1 μm or more, more preferably 5 μm or more, and even more preferably 10 μm or more. The thickness of the photocurable pressure-sensitive adhesive layer is preferably 100 μm or less, more preferably 50 μm or less, and even more preferably 30 μm or less. Any combination of these lower limit values ​​and upper limit values ​​may be used. When the thickness of the photocurable pressure-sensitive adhesive layer is 1 μm or more, the adhesion to the adherend is good. When the thickness of the photocurable pressure-sensitive adhesive layer is 100 μm or less, the occurrence of adhesive residue can be suppressed.

[0104] The thickness ratio of the intermediate layer to the photocurable pressure-sensitive adhesive layer (intermediate layer / photocurable pressure-sensitive adhesive layer) is preferably 1 to 50, more preferably 1 to 40, and even more preferably 1 to 30. When the thickness ratio is within the above range, both the ability to conform to irregularities and heat resistance can be achieved. The thickness ratio of the intermediate layer to the photocurable pressure-sensitive adhesive layer (intermediate layer / photocurable pressure-sensitive adhesive layer) may be 3 to 20, or may be 5 to 15.

[0105] (Ethylenically Unsaturated Group-Containing (Meth)acrylic Resin (A2)) The ethylenically unsaturated group-containing (meth)acrylic resin (A2) is not particularly limited, as long as it is an adduct of an epoxy group-containing ethylenically unsaturated compound (a2-3) to a copolymer containing at least a carboxy group-containing ethylenically unsaturated compound (a2-2) as a raw material monomer. The present inventors have found that when an ethylenically unsaturated group is introduced into the side chain of the (meth)acrylic resin using a compound having an isocyanato group in a pressure-sensitive adhesive layer, adhesive residue on the adherend is likely to occur. In addition, compounds separated from the (meth)acrylic resin due to cleavage of the urethane bond formed during the reaction between the compound having an isocyanato group and the (meth)acrylic resin during the heating step are also thought to be a contributing factor to adhesive residue. On the other hand, by forming a photocurable adhesive layer using an ethylenically unsaturated group-containing (meth)acrylic resin (A2), which is an adduct of an epoxy group-containing ethylenically unsaturated compound (a2-3) to a carboxyl group-containing (meth)acrylic copolymer, the semiconductor processing protective sheet has high heat resistance and maintains high conformability to the unevenness of the adherend even when exposed to high temperature conditions from the step of attaching to the adherend, to the processing step, and the peeling step. In addition, when peeling the semiconductor processing protective sheet from the adherend after the processing step, good peelability can be obtained by irradiating with active energy rays.

[0106] Preferably, the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) contains an alkyl(meth)acrylate (a2-1) and a carboxy group-containing ethylenically unsaturated compound (a2-2). More preferably, the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) contains at least one monomer selected from 2-ethylhexyl(meth)acrylate and n-butyl(meth)acrylate. The total content of 2-ethylhexyl(meth)acrylate and n-butyl(meth)acrylate relative to the total content of the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is preferably 50 mol % or more, more preferably 60 mol % or more. The upper limit of the total content of 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate relative to the total content of the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is not particularly limited, and may be, for example, 99 mol %, 90 mol %, or 80 mol %.

[0107] The ethylenically unsaturated group-containing (meth)acrylic resin (A2) may be used alone or in combination of two or more kinds.

[0108] The glass transition temperature (Tg) of the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is preferably −80° C. to 0° C., more preferably −70° C. to −10° C., and even more preferably −60° C. to −20° C. When the glass transition temperature is −80° C. or higher, a photocurable pressure-sensitive adhesive layer with high cohesive strength is obtained, thereby preventing resin elution during sheet molding. When the glass transition temperature is 0° C. or lower, the adhesion between the intermediate layer and the photocurable pressure-sensitive adhesive layer is further improved.

[0109] The weight-average molecular weight of the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is preferably 100,000 to 2,000,000, more preferably 150,000 to 1,500,000, and even more preferably 200,000 to 1,000,000. When the weight-average molecular weight is 100,000 or more, a photocurable pressure-sensitive adhesive layer with high cohesive strength can be obtained, and resin elution during sheet formation can be prevented. When the weight-average molecular weight is 2,000,000 or less, forming and processing are easy.

[0110] The ethylenically unsaturated group equivalent of the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is preferably 500 g / mol or more, more preferably 550 g / mol or more, and even more preferably 600 g / mol or more. The ethylenically unsaturated group equivalent of the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is preferably 5000 g / mol or less, more preferably 4000 g / mol or less, and even more preferably 2000 g / mol or less. The ethylenically unsaturated group equivalent of the ethylenically unsaturated group-containing (meth)acrylic resin (A2) may be 1500 g / mol or less, or may be 1000 g / mol or less. Any combination of these lower limit values ​​and upper limit values ​​may be used. When the ethylenically unsaturated group equivalent is within the above range, sufficient curability can be imparted.

[0111] The acid value of the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is preferably 1 mgKOH / g or more, more preferably 5 mgKOH / g or more, and even more preferably 10 mgKOH / g or more. The acid value of the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is preferably 100 mgKOH / g or less, more preferably 50 mgKOH / g or less, and even more preferably 35 mgKOH / g or less. Any combination of these lower and upper limits may be used. When the acid value is 1 mgKOH / g or more, the resin can sufficiently react with a crosslinking agent having a functional group reactive with an acid group, resulting in a photocurable pressure-sensitive adhesive layer with high cohesive strength. When the acid value is 100 mgKOH / g or less, the cohesive strength of the resulting resin is not too high, making it easy to handle. By setting the acid value within the above range, the amount of crosslinking with the crosslinking agent (B2) can be adjusted, and the storage modulus of the photocurable pressure-sensitive adhesive layer can be adjusted to a desired range. Specifically, it is possible to increase the storage modulus of the photocurable pressure-sensitive adhesive layer by increasing the amount of crosslinking, or to decrease the storage modulus of the photocurable pressure-sensitive adhesive layer by decreasing the amount of crosslinking.

[0112] The content of the carboxyl group-containing ethylenically unsaturated compound (a2-2) in the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is preferably 1 to 60 mol%, more preferably 5 to 50 mol%, and even more preferably 10 to 40 mol%. When the content of the carboxyl group-containing ethylenically unsaturated compound (a2-2) is 1 mol% or more, the amount of crosslinking with the crosslinking agent (B2) is sufficiently ensured, thereby improving the cohesive strength of the photocurable pressure-sensitive adhesive layer. In addition, the storage modulus of the photocurable pressure-sensitive adhesive layer can be improved, thereby suppressing side stickiness of the semiconductor processing protective sheet, resin sagging during heating, and adhesive residue after UV irradiation. Furthermore, the introduction of a sufficient amount of ethylenically unsaturated groups can be ensured, thereby sufficiently reducing the peel strength of the semiconductor processing protective sheet when irradiated with active energy rays. When the content of the carboxyl group-containing ethylenically unsaturated compound (a2-2) is 60 mol% or less, the storage modulus of the photocurable pressure-sensitive adhesive layer is not too high, resulting in good step-conformability.

[0113] The amount of the epoxy group-containing ethylenically unsaturated compound (a2-3) is preferably 0.5 to 55 mol, more preferably 1 to 45 mol, and even more preferably 3 to 35 mol, per 100 mol of the monomer group (M2). The addition rate of the epoxy group-containing ethylenically unsaturated compound (a2-3) relative to the carboxy groups derived from the carboxy group-containing ethylenically unsaturated compound (a2-2) is preferably 10 to 99%, more preferably 15 to 95%, and even more preferably 20 to 85%. By setting the amount within the above range, it is possible to ensure a sufficient amount of ethylenically unsaturated groups introduced while ensuring the amount of crosslinking with the crosslinking agent (B2).

[0114] The monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) may, if necessary, contain at least one selected from the group consisting of alkyl (meth)acrylates (a2-1) and other monomers (a2-4).

[0115] The content of alkyl (meth)acrylate (a2-1) in the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is preferably 40 to 99 mol%, more preferably 50 to 90 mol%, and even more preferably 60 to 85 mol%. When the content of alkyl (meth)acrylate (a2-1) is 40 mol% or more, adhesion to the intermediate layer is good. When the content of alkyl (meth)acrylate (a2-1) is 99 mol% or less, the content of carboxy group-containing ethylenically unsaturated compound (a2-2) can be sufficiently ensured, thereby ensuring a sufficient amount of crosslinking with the crosslinking agent (B2) and improving the cohesive strength of the photocurable pressure-sensitive adhesive layer. In addition, since the introduction amount of ethylenically unsaturated groups can be sufficiently ensured, the peel strength of the semiconductor processing protection sheet can be sufficiently reduced when irradiated with active energy rays. Note that the storage modulus of the photocurable pressure-sensitive adhesive layer can be adjusted by adjusting the content of alkyl (meth)acrylate (a2-1). Specifically, the storage modulus of the photocurable pressure-sensitive adhesive layer can be decreased by increasing the content of alkyl (meth)acrylate (a2-1), or the storage modulus of the photocurable pressure-sensitive adhesive layer can be increased by decreasing the content of alkyl (meth)acrylate (a2-1).

[0116] When the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) contains the other monomer (a2-4), the content thereof is preferably 0.1 to 30 mol %, more preferably 0.1 to 20 mol %, and even more preferably 0.1 to 10 mol %.

[0117] Specific examples and suitable examples of the alkyl (meth)acrylate (a2-1) are the same as those of the alkyl (meth)acrylate (a1-1). The alkyl (meth)acrylate (a2-1) may be used alone or in combination of two or more. Specific examples and suitable examples of the carboxy group-containing ethylenically unsaturated compound (a2-2) are the same as those of the carboxy group-containing ethylenically unsaturated compound (a1-3). The carboxy group-containing ethylenically unsaturated compound (a2-2) may be used alone or in combination of two or more.

[0118] The epoxy group-containing ethylenically unsaturated compound (a2-3) is not particularly limited as long as it does not have a carboxy group and has an epoxy group and an ethylenically unsaturated group. In the present disclosure, the term "epoxy group-containing ethylenically unsaturated compound" also encompasses ethylenically unsaturated compounds containing an oxetane ring instead of an epoxy group. Specific examples include glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexane-1-allyl carboxylate, 3,4-epoxytricyclo[5.2.1.0]propanol ... ２，６ ]decaneoxyethyl acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, etc. Among these, glycidyl (meth)acrylate is preferred from the viewpoint of ease of synthesis, and 3,4-epoxycyclohexylmethyl (meth)acrylate is preferred from the viewpoint of heat resistance. The epoxy group-containing ethylenically unsaturated compound (a2-3) may be used alone or in combination of two or more types.

[0119] As the other monomer (a2-4) other than (a2-1) and (a2-2), the same compounds as the hydroxy group-containing (meth)acrylate (a1-2) and the other monomer (a1-4) can be used. The other monomer (a2-4) may be used alone or in combination of two or more.

[0120] (Crosslinking Agent (B2)) The crosslinking agent (B2) is not particularly limited as long as it is a compound having multiple functional groups capable of reacting with any of the multiple functional groups possessed by the ethylenically unsaturated group-containing (meth)acrylic resin (A2). Since the ethylenically unsaturated group-containing (meth)acrylic resin (A2) has a carboxy group, examples of crosslinking agents (B2) that can be used include epoxy crosslinking agents and aziridine crosslinking agents. By including the crosslinking agent (B2) in the photocurable pressure-sensitive adhesive layer, the cohesive strength of the photocurable pressure-sensitive adhesive layer is improved, and adhesive residue can be reduced when the semiconductor processing protection sheet is peeled from the adherend. The crosslinking agent (B2) may be used alone or in combination of two or more types.

[0121] The epoxy crosslinking agent and aziridine crosslinking agent may be the same as those used as the crosslinking agent (B1). The epoxy crosslinking agent may be used alone or in combination of two or more. The aziridine crosslinking agent may be used alone or in combination of two or more.

[0122] The content of the crosslinking agent (B2) is preferably 0.05 to 30 parts by mass, more preferably 0.1 to 20 parts by mass, and even more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the ethylenically unsaturated group-containing (meth)acrylic resin (A2). When the content of the crosslinking agent (B2) is 0.05 parts by mass or more, a three-dimensional crosslinked structure is sufficiently formed in the photocurable pressure-sensitive adhesive layer, resulting in a photocurable pressure-sensitive adhesive layer with sufficiently high cohesive strength. In addition, the storage modulus of the photocurable pressure-sensitive adhesive layer can be improved, thereby suppressing side stickiness of the semiconductor processing protective sheet, resin sagging during heating, and adhesive residue on the adherend after UV irradiation. When the content of the crosslinking agent (B2) is 30 parts by mass or less, an appropriate gelation time can be ensured during sheet molding. Furthermore, the storage modulus of the photocurable pressure-sensitive adhesive layer is not too high, resulting in good adhesion to the adherend and intermediate layer, as well as good conformability to uneven surfaces.

[0123] (Photopolymerization initiator (C)) Examples of the photopolymerization initiator (C) include benzophenone, benzil, benzoin, ω-bromoacetophenone, chloroacetone, acetophenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bisdiethylaminobenzophenone, Michler's ketone, benzoin methyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyl methyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, Examples of the photopolymerization initiator include carbonyl-based photopolymerization initiators such as methyl benzoyl formate, 4'-dimethylaminoacetophenone, and 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one; sulfide-based photopolymerization initiators such as diphenyl disulfide, dibenzyl disulfide, tetraethyl thiuram disulfide, and tetramethylammonium monosulfide; acyl phosphine oxide-based photopolymerization initiators such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 2,4,6-trimethylbenzoylphenylethoxyphosphine oxide; quinone-based photopolymerization initiators such as benzoquinone and anthraquinone; sulfochloride-based photopolymerization initiators; and thioxanthone-based photopolymerization initiators such as thioxanthone, 2-chlorothioxanthone, and 2-methylthioxanthone.

[0124] Among these, it is preferable to use a carbonyl-based photopolymerization initiator or an acylphosphine oxide-based photopolymerization initiator from the viewpoint of high sensitivity to ultraviolet light and heat resistance.

[0125] The photopolymerization initiator (C) may be used alone or in combination of two or more kinds.

[0126] The content of the photopolymerization initiator (C) is preferably 0.1 to 10.0 parts by mass, more preferably 0.5 to 5.0 parts by mass, per 100 parts by mass of the ethylenically unsaturated group-containing (meth)acrylic resin (A2). When the content of the photopolymerization initiator (C) is 0.1 parts by mass or more, the photocurable pressure-sensitive adhesive layer can be cured at a sufficiently fast curing rate by irradiation with active energy rays, thereby sufficiently reducing the peel strength of the pressure-sensitive adhesive layer after irradiation with active energy rays. When the content of the photopolymerization initiator (C) is 10.0 parts by mass or less, the pressure-sensitive adhesive layer is less likely to remain on the adherend when the semiconductor processing protective sheet is peeled from the adherend. Even if the content of the photopolymerization initiator (C) exceeds 10.0 parts by mass, the effect commensurate with the content of the photopolymerization initiator (C) is not observed, so by setting the content to 10.0 parts by mass or less, the pressure-sensitive adhesive composition can be produced economically.

[0127] (Other Components) The pressure-sensitive adhesive composition used in the photocurable pressure-sensitive adhesive layer may contain other components in addition to the above-mentioned ethylenically unsaturated group-containing (meth)acrylic resin (A2), crosslinking agent (B2), and photopolymerization initiator (C), as necessary. Examples of other components include a tackifier, a solvent, and various additives. As the tackifier, solvent, and various additives, the same ones as those described for the resin composition for the intermediate layer can be used.

[0128] [Method for producing ethylenically unsaturated group-containing (meth)acrylic resin (A2)] The method for producing the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is not particularly limited. The ethylenically unsaturated group-containing (meth)acrylic resin (A2) can be obtained, for example, by copolymerizing raw material monomers by a known polymerization method, and then adding an epoxy group-containing ethylenically unsaturated compound (a2-3) to some of the carboxy groups in the copolymer.

[0129] The copolymer used for producing the ethylenically unsaturated group-containing (meth)acrylic resin (A2) can be obtained by the same method as the method for producing the ethylenically unsaturated group-free (meth)acrylic resin (A1). Among these, solution polymerization is preferred, and the type and amount of radical polymerization initiator and solvent used are also the same as those described for the method for producing the ethylenically unsaturated group-free (meth)acrylic resin (A1).

[0130] When a carboxy group-containing copolymer is produced as the copolymer used in producing the ethylenically unsaturated group-containing (meth)acrylic resin (A2) and the epoxy group-containing ethylenically unsaturated compound (a2-3) is added to a portion of the carboxy groups of the copolymer, the temperature of the addition reaction is preferably 80 to 150°C, and particularly preferably 90 to 130°C. When the temperature of the addition reaction is 80°C or higher, a sufficient reaction rate can be obtained. When the temperature of the addition reaction is 150°C or lower, crosslinking of the double bonds due to thermal radical polymerization can be prevented, preventing the formation of a gelled product.

[0131] In the addition reaction, a known catalyst can be used as necessary. Examples of the catalyst include primary amines such as n-butylamine, n-hexylamine, benzylamine, diethylenetriamine, triethylenetetramine, and diethylaminopropylamine; tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, 1,8-diazabicyclo[5.4.0]undec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, and 1,4-diazabicyclo[2.2.2]octane; aromatic amines such as aniline, toluidine, phenylenediamine, diaminodiphenylmethane, and 1,8-diaminonaphthalene; pyridine compounds such as pyridine, 2,6-lutidine, and 4-dimethylaminopyridine; imidazole compounds such as imidazole, 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4-methylimidazole; and tetramethylamine. ammonium salts such as tetrabutylammonium chloride, tetramethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium iodide, and tetrabutylammonium hydroxide; alkyl ureas such as tetramethylurea; alkyl guanidines such as tetramethylguanidine; and phosphine compounds such as triphenylphosphine, dimethylphenylphosphine, tricyclohexylphosphine, tributylphosphine, tris(4-methylphenyl)phosphine, tris(4-methoxyphenyl)phosphine, tris(2,6-dimethylphenyl)phosphine, tris(2,6-dimethoxyphenyl)phosphine, tris(2,4,6-trimethylphenyl)phosphine, and tris(2,4,6-trimethoxyphenyl)phosphine;and phosphonium salts such as tetraphenylphosphonium chloride, tetraphenylphosphonium bromide, tetraphenylphosphonium iodide, tetraphenylphosphonium tetraphenylborate, tetraphenylphosphonium tetrakispentafluorophenylborate, 4-hydroxyphenyl-2-(triphenylphosphonium)phenolate, 4-hydroxyphenyl-2-{tris-(4-methylphenyl)phosphonium}phenolate, benzyltriphenylphosphonium chloride, methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, butyltriphenylphosphonium bromide, and tetraphenylphosphonium bromide. Among these, from the viewpoint of reactivity, it is preferable to use a pyridine compound, an imidazole compound, an ammonium salt, a phosphine compound, or a phosphonium salt.

[0132] The amount of the catalyst used in the addition reaction is preferably 0.01 to 20 parts by mass, more preferably 0.05 to 10 parts by mass, and even more preferably 0.1 to 5 parts by mass, per 100 parts by mass of the copolymer and the epoxy group-containing ethylenically unsaturated compound (a2-3) in total.

[0133] Furthermore, during the addition reaction, a gas having a polymerization-inhibiting effect may be introduced into the reaction system, or a polymerization inhibitor may be added. By introducing a gas having a polymerization-inhibiting effect into the reaction system, or by adding a polymerization inhibitor, gelation during the addition reaction can be prevented.

[0134] Examples of gases that have a polymerization-inhibiting effect include gases that contain oxygen to an extent that does not fall within the explosive range of the substances in the system, such as air.

[0135] The polymerization inhibitor may be any known one and is not particularly limited, but examples thereof include 4-methoxyphenol, hydroquinone, methoquinone, 2,6-di-t-butylphenol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), and phenothiazine. The polymerization inhibitor may be used alone or in combination of two or more.

[0136] The amount of the polymerization inhibitor used is preferably 0.005 to 5 parts by mass, more preferably 0.03 to 3 parts by mass, and even more preferably 0.05 to 1.5 parts by mass, relative to 100 parts by mass of the total of the copolymer and the epoxy group-containing ethylenically unsaturated compound (a2-3). If the amount of the polymerization inhibitor used is 0.005 parts by mass or more, gelation during the addition reaction can be prevented. On the other hand, if the amount of the polymerization inhibitor used is 5 parts by mass or less, sufficient exposure sensitivity of the photocurable pressure-sensitive adhesive layer can be obtained when irradiated with active energy rays.

[0137] It is more preferable to use a gas having a polymerization inhibitor effect in combination with a polymerization inhibitor, since this allows the amount of polymerization inhibitor used to be reduced and the polymerization inhibitor effect to be enhanced.

[0138] [Method for producing pressure-sensitive adhesive composition] The pressure-sensitive adhesive composition can be produced by a conventionally known method, for example, by mixing and stirring the ethylenically unsaturated group-containing (meth)acrylic resin (A2), the crosslinking agent (B2), the photopolymerization initiator (C), and other components, such as a tackifier, a solvent, and various additives, which may be contained as needed, by a conventionally known method.

[0139] The method for mixing and stirring the components contained in the PSA composition is not particularly limited. Mixing and stirring can be performed using, for example, a stirring device equipped with stirring blades such as a homodisper or paddle blade.

[0140] [Method for producing photocurable pressure-sensitive adhesive layer] The photocurable pressure-sensitive adhesive layer can be produced, for example, by the method shown below. First, a pressure-sensitive adhesive composition is applied onto a release sheet, and if a solvent is contained, the composition is heated and dried to remove the solvent, thereby forming a pre-thermally cured photocurable pressure-sensitive adhesive layer. Thereafter, if necessary, a release sheet may be attached to the surface of the pre-thermally cured photocurable pressure-sensitive adhesive layer that is to be attached to the intermediate layer or the pre-cured intermediate layer until immediately before lamination onto the intermediate layer or the pre-cured intermediate layer. The pre-thermally cured photocurable pressure-sensitive adhesive layer may undergo a curing reaction by heat curing the obtained sheet in an oven or the like for a certain period of time, thereby forming a crosslinked structure. The curing reaction may be carried out after laminating the intermediate layer or the pre-cured intermediate layer and the pre-thermally cured photocurable pressure-sensitive adhesive layer.

[0141] The photocurable pressure-sensitive adhesive layer can also be produced by the following method. A pressure-sensitive adhesive composition is applied directly onto the intermediate layer of a sheet having an intermediate layer on one main surface of a substrate. If a solvent is contained, the composition is heated and dried to remove the solvent, thereby forming a pre-thermally cured photocurable pressure-sensitive adhesive layer. Thereafter, if necessary, a release sheet is laminated onto the pre-thermally cured photocurable pressure-sensitive adhesive layer. The resulting sheet is then processed as described above to form a crosslinked structure. When a thermosetting intermediate layer is used, a pressure-sensitive adhesive composition may be applied directly onto the pre-cured intermediate layer of a sheet having a pre-cured intermediate layer on one main surface of a substrate. If a solvent is contained, the composition is heated and dried to remove the solvent, thereby forming a pre-thermally cured photocurable pressure-sensitive adhesive layer. Thereafter, if necessary, a release sheet is laminated onto the pre-thermally cured photocurable pressure-sensitive adhesive layer. Then, the pre-cured intermediate layer and the pre-thermally cured photocurable pressure-sensitive adhesive layer are simultaneously cured. These methods can omit the step of laminating an intermediate layer and a photocurable pressure-sensitive adhesive layer to obtain a protective sheet for semiconductor processing.

[0142] The method for applying the pressure-sensitive adhesive composition onto a release sheet (or onto an intermediate layer or a pre-cured intermediate layer), the conditions and preferred ranges for heating and drying the applied pressure-sensitive adhesive composition, and the conditions and preferred ranges for curing the pre-thermosetting photocurable pressure-sensitive adhesive layer after heating and drying in an oven for a certain period of time are the same as those described for the method for producing the intermediate layer.

[0143] (Release Sheet (Separator)) As the release sheet, any known sheet-shaped material can be appropriately selected and used. As the release sheet, the same material as the above-mentioned resin sheet used as the substrate can be used.

[0144] The thickness of the release sheet can be appropriately selected depending on the application of the protective sheet for semiconductor processing, the material of the release sheet, etc. When a resin sheet is used as the release sheet, the thickness of the release sheet is preferably 5 to 300 μm, more preferably 10 to 200 μm, and even more preferably 25 to 100 μm.

[0145] The release surface of the release sheet, i.e., the surface that is placed in contact with the photocurable pressure-sensitive adhesive layer, may be subjected to a release treatment using a conventionally known release agent such as a silicone-based, long-chain alkyl-based, or fluorine-based release agent, if necessary.

[0146] [Method for manufacturing the protective sheet for semiconductor processing] The protective sheet for semiconductor processing can be manufactured, for example, by laminating an intermediate layer and a photocurable pressure-sensitive adhesive layer. When a thermosetting intermediate layer is used, the protective sheet for semiconductor processing may be manufactured by first curing either the pre-curing intermediate layer or the pre-thermosetting photocurable pressure-sensitive adhesive layer, and then laminating the other pre-curing layer and curing the pre-curing layer, or by laminating the pre-curing intermediate layer and the pre-thermosetting photocurable pressure-sensitive adhesive layer and curing both layers simultaneously.

[0147] A specific example of a method for producing a protective sheet for semiconductor processing using a thermosetting intermediate layer is shown below. A sheet having a pre-cured intermediate layer on one main surface of a substrate and a sheet having a pre-thermosetting light-curable adhesive layer on a release sheet are prepared. If a release sheet is laminated on the bonding surfaces of the two sheets, it is peeled off, and the sheets are bonded together with the bonding surface of the pre-cured intermediate layer (i.e., the surface opposite the substrate) facing the bonding surface of the pre-thermosetting light-curable adhesive layer (i.e., the surface opposite the release sheet).

[0148] The pre-cured intermediate layer and the pre-thermosetting photocurable pressure-sensitive adhesive layer are then heated in an oven for a certain period of time (curing step) while the pre-cured intermediate layer and the pre-thermosetting photocurable pressure-sensitive adhesive layer are thermally cured to obtain a cured product of both layers. The conditions for the curing step are not particularly limited, but curing is typically performed at 30 to 100°C, preferably 40 to 80°C, for 1 to 14 days, preferably 1 to 7 days. Curing under these conditions can adjust the storage modulus of each layer to a desired range. Depending on the combination of components, crosslinking at the interface between the intermediate layer and the photocurable pressure-sensitive adhesive layer, i.e., crosslinking between the resin in the intermediate layer and the crosslinking agent (B2) in the photocurable pressure-sensitive adhesive layer, and crosslinking between the ethylenically unsaturated group-containing (meth)acrylic resin (A2) in the photocurable pressure-sensitive adhesive layer and the crosslinking agent in the intermediate layer, can also be expected. Therefore, the curing step is expected to improve the interlayer adhesion between the intermediate layer and the photocurable pressure-sensitive adhesive layer.

[0149] [Method for manufacturing a semiconductor device having bump electrodes] In one embodiment, a method for manufacturing a semiconductor device having bump electrodes includes a protection step of attaching the photocurable adhesive layer surface of a protective sheet for semiconductor processing to the surface of the semiconductor device with bump electrodes, an active energy ray irradiation step of irradiating the protective sheet for semiconductor processing with active energy rays to photocure the photocurable adhesive layer, a heating step of the semiconductor device with the protective sheet for semiconductor processing attached, and a peeling step of peeling the protective sheet for semiconductor processing from the surface with bump electrodes. Note that a processing step may be performed between the protection step and the peeling step, and the order of the other steps may be reversed as long as the protection step is performed first and the peeling step is performed last.

[0150] (Protection Process) In the protection process, the photocurable adhesive layer surface of the semiconductor processing protective sheet is attached to the bump electrode-bearing surface of a semiconductor device having bump electrodes. This protects the bump electrode-bearing surface of the semiconductor device. Specific examples of semiconductor devices include semiconductor devices with uneven surfaces, such as bumped semiconductor chips, bumped printed wiring boards (PCBs), and bumped flexible printed circuit boards (FPCs). These semiconductor devices are subjected to various processing steps in the manufacturing process up to the mounting step in which the bump electrodes are connected to other electronic devices. Protecting the bump electrode-bearing surface during the processing steps can prevent scratches, damage, contamination, etc. on the bump electrode-bearing surface. The semiconductor processing protective sheet can also serve as a temporary fixation function for the semiconductor device for subsequent processing steps.

[0151] When the height of the bump electrode is H [μm] and the total thickness of the intermediate layer and the photocurable adhesive layer is d [μm], d / H is preferably 1.00 or more, more preferably 1.05 or more, and even more preferably 1.10 or more. d / H is preferably 100 or less, more preferably 20 or less, and even more preferably 10 or less. Any combination of these lower and upper limits may be used.

[0152] When a release sheet is provided on the photocurable pressure-sensitive adhesive layer, the release sheet can protect the photocurable pressure-sensitive adhesive layer until use. When a release sheet is provided on the photocurable pressure-sensitive adhesive layer, the release sheet can be peeled off to expose the photocurable pressure-sensitive adhesive layer, and the photocurable pressure-sensitive adhesive layer (adhesion surface) can be efficiently pressure-bonded to the bump electrode-bearing surface of a semiconductor device.

[0153] When a semiconductor device has a plurality of surfaces with bump electrodes, a protective sheet for semiconductor processing is attached to some or all of the surfaces with bump electrodes in the protection step. For example, when stacking semiconductor chips as disclosed in JP 2014-225546 A, a protective sheet for semiconductor processing can be attached to the non-mounting surfaces excluding the mounting surfaces of the surfaces with bump electrodes.

[0154] (Processing Step) The method for manufacturing a semiconductor device may include a processing step between the protection step and the peeling step described below.

[0155] As the processing step, any processing step used in the manufacture of conventionally known semiconductor devices can be applied without any particular restrictions. For example, when the protective sheet for semiconductor processing used in the protection step is used as a dicing tape for a wafer, the protective sheet for semiconductor processing is attached to a wafer on which a plurality of components are formed in the protection step, and then the wafer is cut and separated (diced) into individual components in the processing step, a dicing step is carried out to obtain element pieces (chips). When a semiconductor chip stacking step is carried out as the processing step, only the non-mounting surface of the surface with bump electrodes is protected in the protection step, and the mounting surfaces on which the protective sheet for semiconductor processing is not attached are brought into contact with each other and electrically connected while being stacked.

[0156] (Heating step) The method for manufacturing a semiconductor device includes a heating step between the protection step and the peeling step described below. When the method for manufacturing a semiconductor device includes a processing step after the protection step, the order of the processing step and the heating step is not limited. From the viewpoint of maximizing the protective function and temporary fixing function of the semiconductor processing protective sheet, i.e., the adhesion performance, it is preferable that the processing step and the heating step are performed simultaneously, or that the processing step is performed before the heating step.

[0157] The heating step can be any heating step known in the art and used in the manufacture of semiconductor devices, including, for example, an after-cure step for a PCB with bumps, a sputtering step for a semiconductor chip, and a reflow step for connecting a semiconductor chip.

[0158] The conditions for the heating step are not particularly limited. By performing the protection step before the heating step, the surface with the bump electrodes can be well protected even when high-temperature treatment is performed, for example, at 150°C or higher, 180°C or higher, or 200°C or higher. The maximum temperature reached in the heating step is not particularly limited, but may be, for example, 80°C or higher or 100°C or higher, and 260°C or lower, or 230°C or lower. Any combination of these lower and upper limits may be used. The maximum temperature reached in the heating step is not particularly limited, but is preferably 300°C, more preferably 270°C, from the viewpoint of the heat resistance of the semiconductor processing protection sheet. The heating time is not particularly limited, but is, for example, 1 minute to 180 minutes, preferably 1 minute to 120 minutes, and more preferably 1 minute to 60 minutes.

[0159] (Active energy ray irradiation step) In the active energy ray irradiation step, active energy rays are usually irradiated from the substrate side of the semiconductor processing protective sheet. When the adherend has light transparency, active energy rays may be irradiated from the adherend side toward the semiconductor processing protective sheet. The active energy ray irradiation can crosslink and harden the photocurable pressure-sensitive adhesive layer, thereby increasing the heat resistance of the semiconductor processing protective sheet or improving the peelability of the semiconductor processing protective sheet. The active energy ray irradiation step may be performed between the protection step and the peeling step described below, and the order of the processing step and the heating step is not limited.

[0160] The active energy ray irradiation step may be carried out twice.For example, the active energy ray irradiation step is carried out between the protection step and the processing step, and a part of the ethylenically unsaturated groups contained in the photocurable pressure-sensitive adhesive layer is crosslinked and cured, thereby improving the heat resistance of the semiconductor processing protection sheet.Furthermore, the second active energy ray irradiation step is carried out immediately before the peeling step described below, and the remaining ethylenically unsaturated groups are crosslinked, thereby reducing the peel strength of the semiconductor processing protection sheet and improving its peelability from the adherend.

[0161] Examples of active energy rays include gamma rays, ultraviolet rays (UV), visible light, infrared rays (heat rays), radio waves, alpha rays, beta rays, electron beams, plasma flow, ionizing rays, and particle beams, with ultraviolet rays (UV) being preferred. Examples of light sources used to irradiate the semiconductor processing protection sheet attached to the adherend with UV before peeling include LED lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, xenon lamps, metal halide lamps, chemical lamps, and black lights. For active energy ray irradiation, it is preferable to use an LED lamp, high-pressure mercury lamp, or metal halide lamp.

[0162] The active energy ray irradiation dose applied to the semiconductor processing protection sheet is 50 to 3000 mJ / cm ２ is preferably 100 to 1500 mJ / cm ２ It is more preferable that the active energy ray irradiation dose applied to the protective sheet for semiconductor processing is 50 mJ / cm. ２ When the amount of active energy rays irradiated to the protective sheet for semiconductor processing is 3000 mJ / cm or more, the photocurable pressure-sensitive adhesive layer can be cured at a sufficiently high curing rate by irradiating the active energy rays, and therefore the adhesive strength of the photocurable pressure-sensitive adhesive layer after irradiating the active energy rays can be sufficiently reduced. ２ Even if the amount exceeds 3000 mJ / cm, no corresponding effect can be obtained. Therefore, the amount of active energy ray irradiation to the protective sheet for semiconductor processing is set to 3000 mJ / cm ２ By setting the following, it is possible to economically crosslink the ethylenically unsaturated groups contained in the photocurable pressure-sensitive adhesive layer while reducing the influence of active energy ray irradiation on the adherend.

[0163] (Peeling Process) In the peeling process, the protective sheet for semiconductor processing is peeled and removed from the surface with the bump electrodes. The peeling process is performed after irradiating with active energy rays to cure the photocurable adhesive layer. By irradiating with active energy rays, the ethylenically unsaturated bonds contained in the photocurable adhesive layer form a three-dimensional crosslinked structure and cure. As a result, the peel strength of the photocurable adhesive layer decreases. Then, the protective sheet for semiconductor processing is peeled from the semiconductor device.

[0164] According to one embodiment of the method for manufacturing a semiconductor device having bump electrodes, even when a heating step is performed, a semiconductor device can be obtained without outgassing and without adhesive residue on the surface of the bumped substrate, and the subsequent mounting step can be performed on the obtained semiconductor device without any problems.

[0165] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0166] The raw materials used are as follows. Alkyl (meth)acrylate (a1-1) or (a2-1): Methyl methacrylate, Nippon Shokubai Co., Ltd., Methyl acrylate, Osaka Organic Chemical Industry Ltd., n-Butyl acrylate, Osaka Organic Chemical Industry Ltd., 2-Ethylhexyl acrylate, Osaka Organic Chemical Industry Ltd., Hydroxy group-containing (meth)acrylate (a1-2) or other monomer (a2-4): 2-Hydroxyethyl acrylate, Nippon Shokubai Co., Ltd. Carboxy group-containing ethylenically unsaturated compound (a1-3) or (a2-2): Acrylic acid, Nippon Shokubai Co., Ltd., Other monomer (a1-4): N,N-Dimethylacrylamide Radical polymerization initiator: 2,2'-Azobis(isobutyronitrile), Fujifilm Wako Pure Chemical Industries, Ltd. Epoxy group-containing ethylenically unsaturated compound (a2-3): 3,4-Epoxycyclohexylmethyl methacrylate, Daicel Corporation, Glycidyl methacrylate, NOF Corporation, FA-512AG (3,4-epoxytricyclo[5.2.1.0 ２，６]decaneoxyethyl acrylate), Hitachi Chemical Co., Ltd., 4HBAGE (4-hydroxybutyl acrylate glycidyl ether), Mitsubishi Chemical Corporation. Isocyanato group-containing ethylenically unsaturated compound: Karenz (trademark) MOI (2-isocyanatoethyl methacrylate), Resonaq Co., Ltd., Crosslinking agent (B1): L-45E (tolylene diisocyanate adduct of trimethylolpropane), Tosoh Corporation, trade name: Coronate L-45E, Tetrad X (N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine]), Mitsubishi Gas Chemical Company, Inc., trade name: TETRAD-X. Crosslinking agent (B2): L-45E (tolylene diisocyanate adduct of trimethylolpropane), Tosoh Corporation, trade name: Coronate L-45E, Tetrad X (N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine]), manufactured by Mitsubishi Gas Chemical Company, Inc., trade name: TETRAD-X PZ-33 (2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate]), manufactured by Nippon Shokubai Co., Ltd., trade name: Chemitite PZ-33 Photopolymerization initiator (C): TPO (2,4,6-trimethylbenzoyldiphenylphosphine oxide), manufactured by BASF Corporation, trade name: L-TPO

[0167] Synthesis Example 1: Production of ethylenically unsaturated group-free (meth)acrylic resin (A1-1) A mixed solution containing 50.0 parts by mass of ethyl acetate, a monomer group (M1) consisting of 98.0 parts by mass of 2-ethylhexyl acrylate and 2.0 parts by mass of 2-hydroxyethyl acrylate, and 2,2′-azobis(isobutyronitrile) (0.05 part by mass relative to 100 parts by mass of the monomer group (M1)) as a polymerization initiator was prepared.

[0168] A four-neck flask equipped with a stirrer, a dropping funnel, a condenser, and a nitrogen inlet tube was charged with 100 parts by mass of ethyl acetate as a solvent, and the temperature was raised to 80°C under a nitrogen gas atmosphere. While maintaining the reaction temperature at 80°C ± 2°C, the mixed solution was uniformly added dropwise to the four-neck flask over 4 hours, and after completion of the addition, stirring was continued for an additional 6 hours at a temperature of 80°C ± 2°C to carry out polymerization, thereby obtaining a reaction solution containing an ethylenically unsaturated group-free (meth)acrylic resin (A1-1) (concentration: 40% by mass, weight average molecular weight (Mw): 700,000, glass transition temperature (Tg): -69°C, hydroxyl value: 9.66 mgKOH / g).

[0169] Synthesis Examples 2 to 5: Production of Ethylenically Unsaturated Group-Free (Meth)acrylic Resins (A1-2) to (A1-5)] Reaction solutions containing ethylenically unsaturated group-free (meth)acrylic resins (A1-2) to (A1-5) were obtained in the same manner as in Synthesis Example 1, except that the raw materials and their blending amounts were as shown in Table 1 and the amount of ethyl acetate was adjusted so that the resin concentration was 40% by mass.

[0170] Synthesis Example 6: Production of ethylenically unsaturated group-containing (meth)acrylic resin (A2-1) A first mixed solution was prepared containing a monomer group (M2) consisting of 82.5 parts by mass of 2-ethylhexyl acrylate and 17.5 parts by mass of acrylic acid, and 2,2′-azobis(isobutyronitrile) (0.10 parts by mass relative to 100 parts by mass of the monomer group (M2)) as a radical polymerization initiator.

[0171] Next, a second mixed solution was prepared containing 31.0 parts by mass of glycidyl methacrylate and 100 parts by mass in total of the monomer group (M2) and glycidyl methacrylate used in the first mixed solution, 1.5 parts by mass of tris(4-methylphenyl)phosphine (TPTP) as a catalyst, and 98.8 parts by mass of butyl acetate as a solvent.

[0172] A four-neck flask equipped with a stirrer, dropping funnel, condenser, and nitrogen inlet tube was charged with 100 parts by mass of butyl acetate as a solvent, and the temperature was raised to 80°C under a nitrogen gas atmosphere. While maintaining the reaction temperature at 80°C ± 2°C, the first mixed solution was uniformly added dropwise to the four-neck flask over a period of 4 hours. After completion of the addition, the mixture was stirred at 80°C ± 2°C for an additional 6 hours to carry out polymerization, yielding a carboxy group-containing copolymer. Thereafter, 4-methoxyphenol (0.15 parts by mass relative to a total of 100 parts by mass of the monomer group (M2) and glycidyl methacrylate) was added to the reaction system as a polymerization inhibitor.

[0173] The reaction system to which 4-methoxyphenol had been added was heated to 100°C, and the second mixed solution was added dropwise over 0.5 hours. After that, stirring was continued at a temperature of 100°C for 8 hours, and the mixture was cooled to room temperature (23°C) to obtain a reaction solution containing an ethylenically unsaturated group-containing (meth)acrylic resin (A2-1) (concentration: 40% by mass, weight average molecular weight (Mw): 500,000, glass transition temperature (Tg): −32°C, acid value: 10.59 mgKOH / g, hydroxyl value: 93.25 mgKOH / g, ethylenically unsaturated group equivalent: 602 g / mol).

[0174] Synthesis Examples 7 to 10: Production of ethylenically unsaturated group-containing (meth)acrylic resins (A2-2) to (A2-5)] Reaction solutions containing ethylenically unsaturated group-containing (meth)acrylic resins (A2-2) to (A2-5) were obtained in the same manner as in Synthesis Example 6, except that the raw materials and their blending amounts were as shown in Table 2 and the amount of butyl acetate was adjusted so that the resin concentration was 40 mass%.

[0175] Comparative Synthesis Example 1: Production of ethylenically unsaturated group-containing (meth)acrylic resin (cA2-1) A mixed solution containing monomer group (M2) consisting of 50 parts by mass of ethyl acetate, 86.5 parts by mass of 2-ethylhexyl acrylate, 13.4 parts by mass of 2-hydroxyethyl acrylate, and 0.1 part by mass of acrylic acid, and 2,2′-azobis(isobutyronitrile) (0.08 part by mass relative to 100 parts by mass of monomer group (M2)) as a radical polymerization initiator was prepared.

[0176] A four-neck flask equipped with a stirrer, a dropping funnel, a condenser, and a nitrogen inlet tube was charged with 50.0 parts by mass of ethyl acetate as a solvent, and the temperature was raised to 80°C under a nitrogen gas atmosphere. While maintaining the reaction temperature at 80°C ± 2°C, the above mixed solution was uniformly added dropwise to the four-neck flask over 4 hours. After completion of the dropwise addition, polymerization was carried out by continuing stirring at a temperature of 80°C ± 2°C for an additional 6 hours. Next, the temperature of the reactant was lowered to 60°C, and a mixed solution of 16.0 parts by mass of 2-isocyanatoethyl methacrylate, 0.05 parts by mass of dibutyltin dilaurate as a urethanization catalyst, and 74 parts by mass of ethyl acetate was added dropwise through the dropping funnel. After completion of the dropwise addition, the reaction system was maintained at 70°C for 4 hours to eliminate the isocyanato groups, thereby obtaining a reaction solution containing an ethylenically unsaturated group-containing (meth)acrylic resin (cA2-1) (concentration: 40% by mass, weight average molecular weight (Mw): 500,000, glass transition temperature (Tg): -42°C, acid value: 0.78 mgKOH / g, hydroxyl value: 5.92 mgKOH / g, ethylenically unsaturated group equivalent: 1125 g / mol).

[0177]

[0178]

[0179] (Production of Intermediate Layer (X1-1) Before Curing) A resin (A1-1) solution containing 30 mass % of resin (A1-1) was obtained by adding ethyl acetate as a dilution solvent to a reaction solution containing the ethylenically unsaturated group-free (meth)acrylic resin (A1-1) (also simply referred to as resin (A1-1)) obtained in Synthesis Example 1. Using the resin (A1-1) solution, a resin composition (X1) for an intermediate layer was obtained by the method shown below.

[0180] In a room shielded from actinic radiation, the resin (A1-1) solution and L-45E as the crosslinking agent (B1) were added to a plastic container in the amounts (parts by mass) shown in Table 3 and stirred to obtain a resin composition (X1) for an intermediate layer. The numerical values ​​for the ethylenically unsaturated group-free (meth)acrylic resin (A1) (also referred to as resin (A1)) solution in Table 3 are the amounts (parts by mass) used of the resin (A1) solution in which the resin (A1) content is 30% by mass. The numerical values ​​for the crosslinking agent (B1) are the amounts (parts by mass) added per 100 parts by mass of the resin (A1) solution.

[0181] The resin composition (X1) was applied directly to a substrate so that the film thickness after heat curing would be 100 μm, and the resulting film was dried by heating at 100°C for 5 minutes to form a pre-cured intermediate layer (X1-1). A release sheet was then attached to the pre-cured intermediate layer (X1-1). A 25 μm thick polyethylene terephthalate (PET) film (E5100, Toyobo Co., Ltd.) was used as the substrate. A 25 μm thick polyethylene terephthalate (PET) film (E7006, Toyobo Co., Ltd.) was used as the release sheet. The film thickness after heat curing was measured on the intermediate layer (X1-1) obtained by curing the pre-cured intermediate layer (X1-1) in an oven at 40°C for 3 days. Samples for measuring the storage modulus (G') at 20°C and 200°C were prepared in the same manner as the samples for film thickness measurement, except that a 75 μm-thick polyethylene terephthalate (PET) film (HY-S10-3, Higashiyama Film Co., Ltd.) was used as the substrate. The storage modulus was measured on a sample obtained by peeling the substrate (HY-S10-3) from the release sheet (E7006).

[0182] (Production of Pre-Cured Intermediate Layer (X2-1)) Resin composition (X2) was obtained in the same manner as for producing resin composition (X1), except that the raw materials and blending amounts shown in Table 3 were used. A pre-cured intermediate layer (X2-1) with a release sheet attached was obtained in the same manner as for producing pre-cured intermediate layer (X1-1), except that resin composition (X2) was used instead of resin composition (X1). Furthermore, the storage modulus (G') at 20°C and 200°C and the film thickness after thermal curing were measured in the same manner as for producing pre-cured intermediate layer (X1-1).

[0183] (Production of Pre-Cure Intermediate Layer (X3-1)) Resin composition (X3) was obtained in the same manner as in the production of resin composition (X1), except that the raw materials and blending amounts listed in Table 3 were used. A pre-cured intermediate layer (X3-1) with a release sheet attached was obtained in the same manner as in the production of pre-cured intermediate layer (X1-1), except that resin composition (X3) was used instead of resin composition (X1), and a 25 μm-thick polyamide (PA) film (EX-25, Unitika Ltd.) was used as the substrate. Furthermore, the storage modulus (G') at 20 ° C. and 200 ° C. and the film thickness after thermal curing were measured in the same manner as in the production of pre-cured intermediate layer (X1-1). The substrate used to prepare the sample for measuring the storage modulus (G') was HY-S10-3.

[0184] (Production of Pre-Cure Intermediate Layer (X4-1)) Resin composition (X4) was obtained in the same manner as in the production of resin composition (X1), except that the raw materials and blending amounts listed in Table 3 were used. A pre-cured intermediate layer (X4-1) with a release sheet attached was obtained in the same manner as in the production of pre-cured intermediate layer (X1-1), except that resin composition (X4) was used instead of resin composition (X1), and a 50 μm-thick polyethylene naphthalate (PEN) film (Q83, Toyobo Co., Ltd.) was used as the substrate. Furthermore, the storage modulus (G') at 20 ° C. and 200 ° C. and the film thickness after thermal curing were measured in the same manner as in the production of pre-cured intermediate layer (X1-1). The substrate used to prepare the sample for measuring the storage modulus (G') was HY-S10-3.

[0185] (Production of Pre-Cured Intermediate Layer (X5-1)) Resin composition (X5) was obtained in the same manner as for producing resin composition (X1), except that the raw materials and blending amounts shown in Table 3 were used. A pre-cured intermediate layer (X5-1) with a release sheet attached was obtained in the same manner as for producing pre-cured intermediate layer (X1-1), except that resin composition (X5) was used instead of resin composition (X1). Furthermore, the storage modulus (G') at 20°C and 200°C and the film thickness after thermal curing were measured in the same manner as for producing pre-cured intermediate layer (X1-1).

[0186] (Production of Pre-Cured Intermediate Layer (X6-1)) Resin composition (X6) was obtained in the same manner as for producing resin composition (X1), except that the raw materials and blending amounts shown in Table 3 were used. A pre-cured intermediate layer (X6-1) with a release sheet attached was obtained in the same manner as for producing pre-cured intermediate layer (X1-1), except that resin composition (X6) was used instead of resin composition (X1). Furthermore, the storage modulus (G') at 20°C and 200°C and the film thickness after thermal curing were measured in the same manner as for producing pre-cured intermediate layer (X1-1).

[0187] (Production of Pre-Cure Intermediate Layer (X2-2)) Resin composition (X2) was obtained in the same manner as resin composition (X1), except that the raw materials and blending amounts listed in Table 3 were used. A pre-cured intermediate layer (X2-2) with a release sheet attached was obtained in the same manner as pre-cured intermediate layer (X1-1), except that resin composition (X2) was used instead of resin composition (X1), and a 25 μm-thick polyamide (PA) film (EX-25, Unitika Ltd.) was used as the substrate. Furthermore, the storage modulus (G') at 20 ° C. and 200 ° C. and the film thickness after thermal curing were measured in the same manner as pre-cured intermediate layer (X1-1). The substrate used to prepare the sample for measuring the storage modulus (G') was HY-S10-3.

[0188] (Production of Pre-Cure Intermediate Layer (X3-2)) Resin composition (X3) was obtained in the same manner as resin composition (X1), except that the raw materials and blending amounts listed in Table 3 were used. A pre-cured intermediate layer (X3-2) with a release sheet attached was obtained in the same manner as pre-cured intermediate layer (X1-1), except that resin composition (X3) was used instead of resin composition (X1), and a 50 μm-thick polyethylene naphthalate (PEN) film (Q83, Toyobo Co., Ltd.) was used as the substrate. Furthermore, the storage modulus (G') at 20°C and 200°C and the film thickness after thermal curing were measured in the same manner as pre-cured intermediate layer (X1-1). The substrate used to prepare the sample for measuring the storage modulus (G') was HY-S10-3.

[0189]

[0190] (Production of Pre-thermally Cured Photocurable Pressure-Sensitive Adhesive Layer (Y1-1)) A resin (A2-1) solution containing 30 mass % of resin (A2-1) was obtained by adding ethyl acetate as a dilution solvent to a reaction solution containing the ethylenically unsaturated group-containing (meth)acrylic resin (A2-1) (also simply referred to as resin (A2-1)) obtained in Synthesis Example 6. A pressure-sensitive adhesive composition (Y1) for a photocurable pressure-sensitive adhesive layer was obtained using the resin (A2-1) solution by the method described below.

[0191] In a room shielded from actinic radiation, the ethylenically unsaturated group-containing (meth)acrylic resin (A2-1), Tetrad X as the crosslinking agent (B2), and TPO as the photopolymerization initiator (C) were added to a plastic container in the blending amounts (parts by mass) shown in Table 4, and the mixture was stirred to obtain a pressure-sensitive adhesive composition (Y1) for a photocurable pressure-sensitive adhesive layer.

[0192] The numerical values ​​for the ethylenically unsaturated group-containing (meth)acrylic resin (A2) (also simply referred to as resin (A2)) solution in Table 4 are the amounts (parts by mass) of the resin (A2) solution used in which the resin (A2) content is 30% by mass. The numerical values ​​for the ethylenically unsaturated group-containing (meth)acrylic resin (cA2) (also simply referred to as resin (cA2)) solution in Table 4 are the amounts (parts by mass) of the resin (cA2) solution used in which the resin (cA2) content is 30% by mass. The numerical values ​​for the crosslinker (B2) and the photopolymerization initiator (C) are the amounts (parts by mass) blended per 100 parts by mass of the resin (A2) solution or the resin (cA2) solution.

[0193] The pressure-sensitive adhesive composition (Y1) was directly coated onto a release sheet (HY-S10-3, a 75 μm-thick polyethylene terephthalate (PET) film, Higashiyama Film Co., Ltd.) so that the film thickness after heat curing would be 10 μm, and the coated layer was dried by heating at 100°C for 2 minutes to form a pre-heat-curing photocurable pressure-sensitive adhesive layer (Y1-1). A release sheet (E7006, a 25 μm-thick polyethylene terephthalate (PET) film, Toyobo Co., Ltd.) was then laminated onto the pre-heat-curing photocurable pressure-sensitive adhesive layer (Y1-1). Measurement of the film thickness after heat curing was performed on the photocurable pressure-sensitive adhesive layer (Y1-1) obtained by curing the pre-heat-curing photocurable pressure-sensitive adhesive layer (Y1-1) in an oven at 40°C for 3 days. Samples for measuring the storage modulus (G') at 20°C and 200°C before photocuring were prepared using the same procedure as the sample for film thickness measurement, except that the film thickness after heat curing was adjusted to 50 μm. The storage modulus was measured for a sample obtained by peeling the release sheet (HY-S10-3) from the release sheet (E7006).

[0194] (Production of Pre-thermally Cured Photocurable Pressure-Sensitive Adhesive Layer (Y2-1)) A pressure-sensitive adhesive composition (Y2) was obtained in the same manner as for the production of pressure-sensitive adhesive composition (Y1), except that the raw materials and blending amounts shown in Table 4 were used. A pre-thermally cured photocurable pressure-sensitive adhesive layer (Y2-1) with a release sheet attached was obtained in the same manner as for the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1), except that pressure-sensitive adhesive composition (Y2) was used instead of pressure-sensitive adhesive composition (Y1). Furthermore, the storage moduli (G') at 20°C and 200°C before photocuring and the film thickness after thermal curing were measured in the same manner as for the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1).

[0195] (Production of Pre-thermally Cured Photocurable Pressure-Sensitive Adhesive Layer (Y3-1)) A pressure-sensitive adhesive composition (Y3) was obtained in the same manner as for the production of pressure-sensitive adhesive composition (Y1), except that the raw materials and blending amounts shown in Table 4 were used. A pre-thermally cured photocurable pressure-sensitive adhesive layer (Y3-1) with a release sheet attached was obtained in the same manner as for the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1), except that pressure-sensitive adhesive composition (Y3) was used instead of pressure-sensitive adhesive composition (Y1), and the film thickness after thermal curing was 15 μm. Furthermore, the storage moduli (G') at 20°C and 200°C before photocuring and the film thickness after thermal curing were measured in the same manner as for the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1).

[0196] (Production of Pre-thermally Cured Photocurable Pressure-Sensitive Adhesive Layer (Y4-1)) A pressure-sensitive adhesive composition (Y4) was obtained in the same manner as for the production of pressure-sensitive adhesive composition (Y1), except that the raw materials and blending amounts shown in Table 4 were used. A pre-thermally cured photocurable pressure-sensitive adhesive layer (Y4-1) with a release sheet attached was obtained in the same manner as for the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1), except that pressure-sensitive adhesive composition (Y4) was used instead of pressure-sensitive adhesive composition (Y1). Furthermore, the storage moduli (G') at 20°C and 200°C before photocuring and the film thickness after thermal curing were measured in the same manner as for the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1).

[0197] (Production of Pre-thermally Cured Photocurable Pressure-Sensitive Adhesive Layer (Y5-1)) A pressure-sensitive adhesive composition (Y5) was obtained in the same manner as for the production of pressure-sensitive adhesive composition (Y1), except that the raw materials and blending amounts shown in Table 4 were used. A pre-thermally cured photocurable pressure-sensitive adhesive layer (Y5-1) with a release sheet attached was obtained in the same manner as for the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1), except that pressure-sensitive adhesive composition (Y5) was used instead of pressure-sensitive adhesive composition (Y1), and the film thickness after thermal curing was set to 15 μm. Furthermore, the storage moduli (G') at 20°C and 200°C before photocuring and the film thickness after thermal curing were measured in the same manner as for the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1).

[0198] (Production of Pre-thermally Cured Photocurable Pressure-Sensitive Adhesive Layer (Y6-1)) A pressure-sensitive adhesive composition (Y6) was obtained in the same manner as the production of pressure-sensitive adhesive composition (Y1), except that the raw materials and blending amounts shown in Table 4 were used. A pre-thermally cured photocurable pressure-sensitive adhesive layer (Y6-1) with a release sheet attached was obtained in the same manner as the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1), except that pressure-sensitive adhesive composition (Y6) was used instead of pressure-sensitive adhesive composition (Y1). Furthermore, the storage moduli (G') at 20°C and 200°C before photocuring and the film thickness after thermal curing were measured in the same manner as the production of pre-thermally cured photocurable pressure-sensitive adhesive layer (Y1-1).

[0199]

[0200] [Example 1] (Production of protective sheet for semiconductor processing) The release sheet was peeled from the pre-curing intermediate layer (X1-1) to which the release sheet had been attached, and the release sheet was peeled from one side of the pre-thermosetting light-curable pressure-sensitive adhesive layer (Y1-1) to which the release sheet had been attached, and the exposed surfaces were bonded together. Thereafter, the sheet was cured in an oven at 40°C for 3 days to crosslink and cure the pre-curing intermediate layer (X1-1) and the pre-thermosetting light-curable pressure-sensitive adhesive layer (Y1-1), thereby obtaining a protective sheet for semiconductor processing of Example 1.

[0201] Examples 2 to 4, Comparative Examples 1 to 4 Protective sheets for semiconductor processing were obtained in the same manner as in Example 1, except that the pre-cured intermediate layer and the pre-thermosetting photocurable pressure-sensitive adhesive layer shown in Table 5 were used.

[0202] The obtained protective sheets for semiconductor processing were evaluated for the following items by the methods described below. The results are shown in Table 5.

[0203] [Peel strength before UV irradiation] The protective sheet for semiconductor processing was cut into a size of 25 mm length and 100 mm width, and the release sheet was peeled off to expose the photocurable adhesive layer. Next, the protective sheet for semiconductor processing was attached to a glass plate so that the exposed photocurable adhesive layer (measurement surface) was in contact with the glass plate, and a 2 kg rubber roller (width: about 50 mm) was rolled back and forth once to obtain a sample for measuring the peel strength before UV irradiation.

[0204] The obtained measurement sample was left for 24 hours in an environment of 23°C and 50% humidity. Thereafter, a tensile test was carried out in the 180° direction at a peel rate of 300 mm / min in an environment of 23°C and 50% humidity using a tensile tester (Texture Analyzer, Eiko Seiki Co., Ltd.) in accordance with JIS Z 0237:2009, to measure the peel strength (N / 25 mm) of the pressure-sensitive adhesive sheet to the glass plate.

[0205] [Peel strength after UV irradiation] The same sample as that for measuring peel strength before UV irradiation was prepared, and the UV irradiation dose was 1000 mJ / cm from the surface of the semiconductor processing protection sheet side. ２ The sample was irradiated with ultraviolet (UV) rays under the conditions of (a) to (c) to obtain a sample for measuring peel strength after UV irradiation. For UV irradiation, a conveyor-type ultraviolet irradiation device (Eye Graphics Co., Ltd., 2 kW lamp, 80 W / cm) was used.

[0206] The peel strength (N / 25 mm) of the pressure-sensitive adhesive sheet to the glass plate of the obtained measurement sample was measured in the same manner as in "Peel strength before UV irradiation."

[0207] [Sheet Cuttability] When the sides of a semiconductor processing protection sheet cut into a size of 25 mm in length and 100 mm in width were brought into contact with each other, the sheet cuttability was evaluated as "good" if they did not re-adhere, and "poor" if they re-adhere.

[0208] [Side Stickiness] Five pieces measuring 25 mm in length and 100 mm in width were cut out of the protective sheet for semiconductor processing, and then the adhesive was visually checked to see if it had adhered to the blade of the cutter knife used for cutting. The stickiness of the sides was evaluated as "good" if no adhesive had adhered, and "poor" if adhesive had adhered.

[0209] [Resin Dripping During Heating] When a sample for measuring peel strength before UV irradiation was heated at 200°C for 2 hours, resin dripping during heating was evaluated as "good" if the adhesive did not ooze out from the edge of the tape, and "poor" if the adhesive oozed out.

[0210] [Adhesive Residue] After heating the sample for measuring peel strength before UV irradiation at 200°C for 2 hours, the sample was irradiated with an amount of 1000 mJ / cm from the surface of the semiconductor processing protection sheet side. ２The protective sheet for semiconductor processing was peeled off from the glass plate under the conditions of ultraviolet (UV) light irradiation under the conditions of 1. The adhesive residue was evaluated as "good" if no adhesive residue remained on the glass surface, and as "poor" if any adhesive residue remained.

[0211] [Gap filling ability: mounting process] The release sheet of the semiconductor processing protective sheet was peeled off to expose the photocurable adhesive layer. Next, the exposed photocurable adhesive layer and a bumped PCB (bump diameter φ = 20 μm, bump spacing 30 μm, bump height 50 or 100 μm) were attached using a mounter (Hugle Electronics, HS7800) at 40 ° C. for 5 minutes to obtain a process test sample. This sample was observed under an optical microscope from the semiconductor processing protective sheet side, and the gap filling ability (mounting process) was evaluated as "excellent" when the area containing bubbles was 1% or less of the entire bumped PCB, "good" when it was more than 1% but less than 10%, and "poor" when it was 10% or more.

[0212] [Step filling ability: dicing process] The process test sample obtained in the mounting process was diced with a blade (SDC200 R100NMR, kerf width: 0.3 mm, blade rotation speed: 28000 rpm, cutting speed: 30 mm / sec, cutting depth: 100 μm, Tokyo Seimitsu Co., Ltd.) to obtain small pieces of process test samples. ２ The photocurable adhesive layer was partially cured by irradiating with UV under the conditions of (a) and (b). A conveyor-type ultraviolet irradiation device (Eye Graphics Co., Ltd., 2 kW lamp, 80 W / cm) was used for UV irradiation. The sample after UV irradiation was observed with an optical microscope from the semiconductor processing protective sheet side, and the step filling ability (dicing process) was evaluated as "excellent" when the area where air bubbles were mixed was 1% or less of the entire PCB with bumps, "good" when the area where air bubbles were mixed was greater than 1% and less than 10%, and "poor" when the area where air bubbles were mixed was 10% or more.

[0213] [Step-filling ability: heating process] The small process test samples obtained in the dicing process were subjected to a heat treatment for 2 hours at 200° C. After cooling, the samples were observed under an optical microscope from the side of the protective sheet for semiconductor processing, and the step-filling ability (heating process) was evaluated as "excellent" when the area where air bubbles were mixed in was 1% or less of the entire PCB with bumps, "good" when the area where air bubbles were mixed in was greater than 1% and less than 10%, and "poor" when the area where air bubbles were mixed in was 10% or more.

[0214]

[0215] In Examples 1 to 4, the sheet cuttability, side stickiness, resin dripping during heating, and adhesive residue were all good, and the step-filling ability for bumps of each height was excellent or good. On the other hand, in Comparative Examples 1 and 3, the step-filling ability was poor. In Comparative Example 2, the sheet cuttability, side stickiness, and resin dripping during heating were poor, and in Comparative Example 4, the adhesive residue was poor. This is thought to be due to the 2-isocyanatoethyl methacrylate used in synthesizing the (meth)acrylic resin (cA2-1) used in Comparative Example 4. Another thought to be a contributing factor is a compound that separated from the (meth)acrylic resin due to cleavage of the urethane bond formed during the addition reaction of 2-isocyanatoethyl methacrylate during the heating process. In Comparative Example 4, the step-filling ability during the heating process was also poor.

[0216] According to the present disclosure, it is possible to provide a protective sheet for semiconductor processing that can accurately follow and adhere to the unevenness of the surface even when the unevenness of the surface of the substrate has large steps (e.g., bump height) or when the sheet has undergone a high-temperature treatment process at 200°C or the like.

[0217] 12 Substrate 14 Intermediate layer 16 Photocurable adhesive layer 18 Release sheet 10 Protective sheet for semiconductor processing

Claims

1. A semiconductor processing protection sheet having a substrate, and an intermediate layer and a photocurable adhesive layer on one main surface of the substrate in this order, wherein the storage modulus (G') of the intermediate layer at 20°C is 5.0 x 10 ４ ~1.0 x 10 ７ Pa, and the storage modulus (G') at 200°C is 5.0 x 10 ３ ~1.0 x 10 ６ The storage modulus (G') of the photocurable pressure-sensitive adhesive layer at 20°C before photocuring is 1.0 x 10 ４ ~1.0 x 10 ７ Pa, and the storage modulus (G') at 200°C before photocuring is 5.0 x 10 ３ ~5.0 x 10 ６ the photocurable pressure-sensitive adhesive layer is a heat-cured product of a pressure-sensitive adhesive composition containing an ethylenically unsaturated group-containing (meth)acrylic resin (A2), a crosslinking agent (B2) and a photopolymerization initiator (C), the ethylenically unsaturated group-containing (meth)acrylic resin (A2) has a plurality of functional groups reactive with a functional group contained in the crosslinking agent (B2), and the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is at least an adduct of an epoxy group-containing ethylenically unsaturated compound (a2-3) to a copolymer having a carboxy group-containing ethylenically unsaturated compound (a2-2) as a raw material monomer.

2. The protective sheet for semiconductor processing according to claim 1, wherein the acid value of the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is 1 to 100 mgKOH / g.

3. The protective sheet for semiconductor processing according to claim 1 or 2, wherein the ethylenically unsaturated group equivalent of the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is 500 to 5000 g / mol.

4. The protective sheet for semiconductor processing according to claim 1 or 2, wherein the crosslinking agent (B2) is at least one selected from the group consisting of epoxy crosslinking agents and aziridine crosslinking agents.

5. A protective sheet for semiconductor processing as described in claim 1 or 2, wherein the intermediate layer is a thermoset product of a resin composition containing an ethylenically unsaturated group-free (meth)acrylic resin (A1) and a crosslinking agent (B1).

6. The semiconductor processing protective sheet according to claim 5, wherein the monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) contains at least one selected from an alkyl (meth)acrylate (a1-1) and a hydroxyl group-containing (meth)acrylate (a1-2) and a carboxyl group-containing ethylenically unsaturated compound (a1-3).

7. The monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) contains at least one selected from 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate, the total content of 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate relative to the total content of the monomer group (M1) constituting the ethylenically unsaturated group-free (meth)acrylic resin (A1) is 50 mol% or more, and the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) contains at least one selected from 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate, The total content of 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate relative to the total of the monomer group (M2) constituting the ethylenically unsaturated group-containing (meth)acrylic resin (A2) is 50 mol% or more. The protective sheet for semiconductor processing according to claim 5.

8. The protective sheet for semiconductor processing according to claim 1 or 2, wherein the substrate comprises at least one selected from the group consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether ether ketone (PEEK), polyamide (PA), and polyimide (PI).

9. The protective sheet for semiconductor processing according to claim 1 or 2, wherein the thickness of the substrate is 5 μm to 300 μm.

10. A protective sheet for semiconductor processing according to claim 1 or 2, wherein the intermediate layer has a thickness of 30 to 600 μm, the photocurable adhesive layer has a thickness of 1 to 100 μm, and the thickness ratio of the intermediate layer to the photocurable adhesive layer (intermediate layer / photocurable adhesive layer) is 1 to 50.

11. A method for manufacturing a semiconductor device having a bump electrode, comprising: a protection step of attaching the photocurable adhesive layer surface of the semiconductor processing protective sheet according to claim 1 or 2 to a surface of a semiconductor device having a bump electrode; an active energy ray irradiation step of irradiating the semiconductor processing protective sheet with active energy rays to photocure the photocurable adhesive layer; a heating step of the semiconductor device to which the semiconductor processing protective sheet is attached; and a peeling step of peeling the semiconductor processing protective sheet from the surface having the bump electrode.

12. The method for manufacturing a semiconductor device according to claim 11, wherein, when the height of the bump electrode is H [μm] and the total thickness of the intermediate layer and the photocurable adhesive layer is d [μm], d / H is 1.00 to 100.

13. The method for producing a semiconductor device according to claim 11, wherein the maximum temperature reached in the heating step is 80 to 260°C.

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