TWI889891B - Adhesive sheet for semiconductor processing and method for manufacturing semiconductor device - Google Patents

Abstract

The present invention relates to an adhesive sheet for semiconductor processing and a method for manufacturing a semiconductor device using the adhesive sheet. The adhesive sheet comprises a substrate and an adhesive layer disposed on one surface of the substrate. The adhesive constituting the adhesive layer has a fracture energy of 7 MJ/ ^m³ or greater as measured by a tensile test (Method 1). The adhesive sheet also has an adhesive strength variation rate of -10% to +10% before and after ultraviolet irradiation (Method 2) as measured by a peel test (Method 2).

Description

Adhesive sheet for semiconductor processing and method for manufacturing semiconductor device

The present invention relates to an adhesive sheet for semiconductor processing and a method for manufacturing a semiconductor device.

With the rapid advancement of thinning, miniaturization, and multifunctionality in information terminal devices, the semiconductor devices used in these devices are also being required to be thinner and more densely packed. One method for reducing the thickness of semiconductor devices is grinding the backside of the semiconductor wafers used to make them. Backside grinding of semiconductor wafers is performed by attaching an adhesive sheet for backside grinding (hereinafter referred to as a "backside grinding sheet") to the surface of the semiconductor wafer, protecting the semiconductor wafer surface. After backside grinding, the backside grinding sheet is peeled off and removed from the semiconductor wafer surface.

Adhesive sheets used to protect the surface of workpieces (hereinafter referred to as "workpieces"), such as back grinding sheets, require high adhesion to prevent accidental peeling from the workpiece during machining in order to effectively protect the workpiece surface. Furthermore, they must also exhibit releasability to prevent contamination of the workpiece during peeling, requiring no adhesive residue to remain on the workpiece.

To achieve both strong adhesion and releasability in adhesive sheets, one method involves imparting energy-beam curability to the adhesive layer. This method allows the workpiece surface to be effectively protected during machining thanks to the high adhesion of the adhesive layer before energy-beam curing. Furthermore, during peeling from the workpiece, the adhesive layer is hardened by energy-beam irradiation, allowing for peeling after the adhesive strength is reduced, thus minimizing the occurrence of residual adhesive.

However, the use of energy-beam-curable adhesive sheets is economically disadvantageous due to the investment required for energy-beam irradiation equipment. Furthermore, the energy beams used to harden the adhesive layer on the workpiece can damage the workpiece's circuitry. Therefore, from the perspectives of cost-effectiveness and productivity, there is a desire for an adhesive sheet for semiconductor processing that can be peeled off without leaving any residue without energy-beam irradiation.

Patent Document 1 discloses a re-peelable adhesive sheet for back grinding of semiconductor wafers, comprising a substrate and an adhesive layer laminated on the substrate. The elastic modulus and thermal shrinkage rate of the re-peelable adhesive sheet, as well as the thickness of the adhesive layer, are within specific ranges. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2011-91220

[Problem to be solved by the invention]

The technology of Patent Document 1 provides a releasable adhesive sheet that can be easily peeled off by minimizing wafer warping, cracking, edge loss, increased adhesion due to temperature fluctuations, and/or reduced contamination of the adherend during repeeling. For this reason, sometimes bumps or other protrusions are provided on the surface of a workpiece, such as a semiconductor wafer. During processing of the back surface of the surface with these protrusions, an adhesive sheet is attached to the surface with these protrusions. This method of use requires sufficient protrusion embedding properties in the adhesive layer of the adhesive sheet to ensure good workpiece retention. On the other hand, since the contact area between the workpiece and the adhesive layer increases due to the embedding of the protrusions, not only does the adhesive layer deform more during peeling, but sufficient embedding of the protrusions requires the adhesive layer to be flexible. Consequently, compared to attaching to a smooth surface, residual sticking is more likely to occur during peeling. While the technology in Patent Document 1 examines the releasability of the adhesive when attached to a smooth surface, it does not fully address the need to suppress residual sticking caused by protrusions such as bumps.

The present invention was developed in light of the above-mentioned circumstances. Its purpose is to provide an adhesive sheet for semiconductor processing that has sufficient protrusion embedding properties and suppresses residual slurry when peeled from a workpiece without irradiation with energy rays, and a method for manufacturing a semiconductor device using the adhesive sheet for semiconductor processing. [Means for Solving the Problem]

As a result of intensive research, the inventors discovered that the aforementioned issues can be resolved by adjusting the fracture energy of the adhesive forming the adhesive layer and the rate of change in the adhesive force of the adhesive sheet before and after ultraviolet irradiation within specific ranges, thereby completing the present invention.

That is, the present invention relates to the following [1] to [11]. [1] An adhesive sheet for semiconductor processing, comprising a substrate and an adhesive layer disposed on one surface of the substrate; the adhesive constituting the adhesive layer has a fracture energy of 7 MJ/ ^m3 or more as measured by a tensile test according to the following method 1; the adhesive sheet has an adhesive force variation rate of -10 to +10% before and after ultraviolet irradiation as measured by a peeling test according to the following method 2; (Method 1) A test piece having a thickness of 0.20 mm, a width of 15 mm, and a length of 140 mm was prepared from the adhesive constituting the above-mentioned adhesive layer. The test piece was subjected to a tensile test under the conditions of 23°C, 50% relative humidity, a tensile speed of 200 mm/min, and a distance between points of 100 mm to measure the fracture energy. (Method 2) A 25 mm wide adhesive sheet was prepared so that the adhesive layer became the adhesive surface. Based on JIS Z0237:2000, the adhesive sheet was attached to the mirror surface of the silicon mirror wafer using a 2kg rubber roller, and then stored in an environment of 23°C and 50% relative humidity for 20 minutes as test piece A. For this test piece A, the adhesive sheet was irradiated from the side at an illumination of 220mW/ ^cm2 and a light intensity of 560mJ/cm ² , and then stored at 23°C and 50% relative humidity for 5 minutes as test piece B; using test pieces A and B, the peeling test of the adhesive sheet was carried out under the conditions of 23°C, 50% relative humidity, 180° peeling angle, and 300 mm/min peeling speed; the adhesive force F1 of the adhesive sheet of test piece A and the adhesive force F2 of the adhesive sheet of test piece B were respectively calculated, and the adhesive force change rate before and after ultraviolet irradiation was calculated by the following formula (1); Adhesion force change rate before and after ultraviolet irradiation (%) = [(F2-F1)/F1]× 100…(1). [2] The adhesive sheet for semiconductor processing as described in [1] above, wherein the thickness of the adhesive layer is 40 μm or greater. [3] The adhesive sheet for semiconductor processing as described in [1] or [2] above, wherein the adhesive force F1 of the adhesive sheet of the test piece A measured by the peeling test of the method 2 is 500 to 5,000 mN/25 mm. [4] The adhesive sheet for semiconductor processing as described in any one of [1] to [3] above, wherein the adhesive layer is formed by an adhesive composition, wherein the adhesive composition comprises: a polymer (A) having a reactive functional group (A1), a polymer (B) having a reactive functional group (B1) different from the reactive functional group (A1) and having a weight average molecular weight lower than that of the polymer (A), a crosslinking agent (C) reactive with the reactive functional group (A1), and a crosslinking agent (D) reactive with the reactive functional group (B1) and different from the crosslinking agent (C). [5] The adhesive sheet for semiconductor processing as described in [4] above, wherein both the polymer (A) and the polymer (B) are non-energy ray curable polymers. [6] The adhesive sheet for semiconductor processing as described in [4] or [5] above, wherein the weight average molecular weight of the polymer (A) is 400,000 to 1,000,000, and the weight average molecular weight of the polymer (B) is 120,000 to 350,000. [7] The adhesive sheet for semiconductor processing as described in any one of [4] to [6] above, wherein the amount of the polymer (B) is 10 to 80 parts by mass relative to 100 parts by mass of the polymer (A). [8] The adhesive sheet for semiconductor processing as described in any one of [4] to [7] above, wherein the functional group equivalent weight of the reactive functional group (B1) in the polymer (B) is 500 to 5,000 g/mol. [9] The adhesive sheet for semiconductor processing according to any one of the above [4] to [8], wherein the reactive functional group (A1) is a carboxyl group, the reactive functional group (B1) is a hydroxyl group, the crosslinking agent (C) is an epoxy crosslinking agent, and the crosslinking agent (D) is an isocyanate crosslinking agent; or the reactive functional group (A1) is a hydroxyl group, the reactive functional group (B1) is a carboxyl group, the crosslinking agent (C) is an isocyanate crosslinking agent, and the crosslinking agent (D) is an epoxy crosslinking agent. [10] The adhesive sheet for semiconductor processing as described in any one of the above [1] to [9] is used as follows: a semiconductor device having a surface with one or more protrusions having a height of 10 μm or more is used as an adherend, and the semiconductor device is processed in a state where the adhesive layer is attached to the surface of the semiconductor device having one or more protrusions. [11] A method for manufacturing a semiconductor device, comprising the steps of processing a semiconductor device having a surface with one or more protrusions having a height of 10 μm or more; and processing the semiconductor device in a state where the adhesive layer of the adhesive sheet for semiconductor processing as described in any one of the above [1] to [10] is attached to the surface of the semiconductor device having one or more protrusions. [Effect of the invention]

According to the present invention, there are provided an adhesive sheet for semiconductor processing that has sufficient convex embedding properties and suppresses residual paste when peeling from a workpiece without irradiation with energy rays, and a method for manufacturing a semiconductor device using the adhesive sheet for semiconductor processing.

In this manual, regarding the preferred numerical range, the lower limit and upper limit values described in the phased description can be combined independently. For example, based on the description of "preferably 10 to 90, more preferably 30 to 60", the "preferable lower limit value (10)" and "preferably upper limit value (60)" can also be combined to become "10 to 60".

In this specification, for example, "(meth)acrylic acid" refers to both "acrylic acid" and "methacrylic acid", and other similar terms are the same.

In this specification, "energy beams" refer to electromagnetic waves or charged particle beams containing energy quanta. Examples include ultraviolet rays, radiation, and electron beams. Ultraviolet rays can be irradiated using, for example, electrodeless lamps, high-pressure mercury lamps, metal halogen lamps, and UV-LEDs. Electron beams can be irradiated using electron beams generated by electron beam accelerators. In this specification, "energy beam polymerizable" refers to the property of polymerizing upon exposure to energy beams. "Energy beam curable" refers to the property of curing upon exposure to energy beams, and "non-energy beam curable" refers to the property of not being energy beam curable.

In this specification, the "front surface" of a semiconductor wafer refers to the side where circuits are formed, and the "back surface" refers to the side where no circuits are formed.

In this manual, solids refer to all ingredients other than organic solvents, including those that are liquid at standard conditions (23°C).

The mechanism of action described in this specification is speculation and does not limit the mechanism by which the adhesive sheet for semiconductor processing of the present invention is effective.

[Adhesive Sheet for Semiconductor Processing] The adhesive sheet for semiconductor processing of this embodiment (hereinafter referred to as "adhesive sheet") comprises a substrate and an adhesive layer disposed on one surface of the substrate. The adhesive sheet of this embodiment may or may not have layers other than the substrate and adhesive layer. Examples of layers other than the substrate and adhesive layer include an intermediate layer disposed between the substrate and the adhesive layer, and a release material disposed on the surface of the adhesive layer opposite the substrate.

<Adhesive Fracture Energy> The adhesive layer of the adhesive sheet of this embodiment is composed of an adhesive having a fracture energy of 7 MJ/ ^m³ or greater, as measured by the tensile test described in Method 1 below. (Method 1) A test piece having a thickness of 0.20 mm, a width of 15 mm, and a length of 140 mm was prepared from the adhesive constituting the adhesive layer. This test piece was subjected to a tensile test under the conditions of 23°C, a relative humidity of 50%, a tensile speed of 200 mm/min, and a distance between points of 100 mm to measure the fracture energy. The tensile test described in Method 1 above is conducted in accordance with JIS K7127:1999. A more specific example is described in the Examples below. The fracture energy is the integral of stress and strain up to the fracture point in the stress-strain curve obtained from the tensile test in Method 1 above.

An adhesive fracture energy of 7 MJ/m³ or ^higher reduces cohesive failure within the adhesive layer, and even when adhered to a surface with protrusions, residual adhesive residue during peeling is suppressed. Based on the same perspective, the adhesive fracture energy is preferably 8 MJ/ ^m³ or higher, more preferably 9 MJ/ ^m³ or higher, and even more preferably 10 MJ/m³ or higher. While the upper limit of the adhesive fracture energy is not particularly limited, it is preferably 30 MJ/ ^m³ or lower, more preferably 25 MJ/ ^m³ or ^lower , and even more preferably 20 MJ/ ^m³ or lower, based on the need for maintaining a good balance with other properties. The adhesive fracture energy can be adjusted by adjusting the polymer composition and monomer composition used to form the adhesive layer.

<Adhesion Variation Rate> The adhesive sheet of this embodiment can be peeled off from the workpiece without irradiation with energy beams. Therefore, the adhesion variation rate before and after ultraviolet irradiation is measured by the peeling test of the following method 2, which is -10 to +10%. (Method 2) A 25mm wide adhesive sheet is made so that the adhesive layer becomes the adhesive surface. Based on JIS Z0237:2000, the adhesive sheet is attached to the mirror surface of a silicon mirror wafer using a 2kg rubber roller. The sheet is then stored in an environment of 23°C and a relative humidity of 50% for 20 minutes. This is referred to as test piece A. For this test piece A, an irradiation of 220mW/ ^cm2 and a light intensity of 560mJ/cm2 is applied from the side of the adhesive sheet. ² , and then stored at 23°C and 50% relative humidity for 5 minutes as test piece B; using test piece A and test piece B, a peeling test of the adhesive sheet was carried out under the conditions of 23°C, 50% relative humidity, a peeling angle of 180°, and a peeling speed of 300 mm/min; the adhesive force F1 of the adhesive sheet of test piece A and the adhesive force F2 of the adhesive sheet of test piece B were respectively calculated, and the adhesive force change rate before and after ultraviolet irradiation was calculated by the following formula (1). Adhesion force change rate before and after ultraviolet irradiation (%) = [(F2-F1)/F1]×100…(1). In addition, a more specific example of the above method 2 is the method described in the embodiment described later.

If the adhesive sheet's adhesion variation rate is between -10% and +10%, even if the sheet is accidentally or intentionally exposed to energy beams during storage, transportation, or use, fluctuations in adhesion are suppressed, resulting in excellent quality stability. Based on the same perspective, the adhesion variation rate is preferably between -7% and +7%, more preferably between -5% and +5%, and even more preferably between -3% and +3%. The adhesion variation rate of an adhesive sheet can be adjusted by adjusting the polymer and monomer compositions used to form the adhesive layer. Specifically, for example, by using a non-energy beam-hardening polymer as the resin constituting the adhesive layer, the adhesion variation rate can be adjusted within the aforementioned range.

Next, the various components constituting the adhesive sheet of this embodiment will be described in more detail.

<Substrate> Resin films are preferred as substrates due to their ease of production and reduced dust generation. Examples of resin films include polyolefin films, halogenated vinyl polymer films, acrylic films, rubber films, cellulose films, polyester films, polycarbonate films, polystyrene films, polyphenylene sulfide films, and cycloolefin polymer films. Among these, polyester films are preferred due to their ease of production, excellent thickness accuracy, and ability to securely hold the workpiece. Polyethylene terephthalate (hereinafter referred to as "PET") films are even more preferred.

When using a resin film as the substrate, the substrate can be a single-layer film consisting of a single resin film or a multilayer film comprising two or more layers. To improve adhesion with other layers, the substrate surface may also be coated. The substrate thickness is not particularly limited, but is preferably 10-200 μm, more preferably 20-100 μm, and even more preferably 30-70 μm. The substrate thickness can be measured using the method described in the Examples.

<Adhesive Layer> The adhesive layer is applied to one surface of the substrate and is bonded to the workpiece. Examples of adhesives used to form the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, polyamide adhesives, urethane adhesives, fluorine adhesives, and styrene-diene block copolymer adhesives. Among these, acrylic adhesives are preferred.

The adhesive layer can be formed from an adhesive composition containing an adhesive-constituting polymer. The adhesive composition preferably includes a polymer (A) having a reactive functional group (A1), a polymer (B) having a reactive functional group (B1) different from the reactive functional group (A1) and having a weight-average molecular weight lower than that of the polymer (A), a crosslinker (C) reactive with the reactive functional group (A1), and a crosslinker (D) reactive with the reactive functional group (B1) and different from the crosslinker (C). The adhesive composition containing the polymer (A), polymer (B), crosslinker (C), and crosslinker (D) is hereinafter referred to as the "adhesive composition (P)."

The polymer (A) contained in the adhesive composition (P) has a reactive functional group (A1), and the polymer (B) has a reactive functional group (B1) different from the reactive functional group (A1). Therefore, polymer (A) is crosslinked by the crosslinking agent (C), and polymer (B) is crosslinked by the crosslinking agent (D). As a result, the adhesive layer formed from the adhesive composition (P) forms a so-called double network, consisting of a three-dimensional network structure formed by polymer (A) and crosslinking agent (C) (hereinafter referred to as the "first network"), and a three-dimensional network structure formed by polymer (B) and crosslinking agent (D) (hereinafter referred to as the "second network"). This double network, consisting of molecules forming the first and second meshes, maintains flexibility while enhancing cohesion. Consequently, adhesives with this double network have excellent conformability to the contours of workpiece ridges, high fracture energy, and a tendency to effectively suppress residual smearing.

The following is a detailed description of the components of the adhesive composition (P).

(Polymer (A) and Polymer (B)) Polymer (A) and polymer (B) react with the crosslinking agent to form the adhesive. Polymer (A) and polymer (B) may be used alone or in combination of two or more.

[Weight Average Molecular Weight] Polymer (A) has a greater weight average molecular weight than polymer (B). This allows for a difference in the density of the crosslinked structures of the first and second meshes, facilitating the formation of a double network that combines the advantages of both crosslinked structures. Based on the same perspective, the difference in weight average molecular weights between polymers (A) and (B) is preferably 100,000 or greater, more preferably 200,000 or greater, and even more preferably 300,000 or greater. Furthermore, to facilitate adjustment of the weight average molecular weights of polymers (A) and (B) within appropriate ranges, the difference in weight average molecular weights between polymers (A) and (B) is preferably 800,000 or less, more preferably 700,000 or less, and even more preferably 500,000 or less. In this specification, the weight average molecular weight is the value calculated based on standard polystyrene measured by gel permeation chromatography (GPC), specifically the value measured based on the method described in the Examples.

The weight-average molecular weight of polymer (A) is not particularly limited, but is preferably 400,000 to 1,000,000, more preferably 450,000 to 800,000, and even more preferably 500,000 to 700,000. When the weight-average molecular weight of polymer (A) is above the lower limit, the first mesh tends to have a structure with excellent flexibility and stretchability, which tends to improve its ability to conform to the contours of workpiece projections. Furthermore, when the weight-average molecular weight of polymer (A) is below the upper limit, the adhesive composition tends to have better coatability.

The weight-average molecular weight of polymer (B) is not particularly limited, but is preferably 120,000 to 350,000, more preferably 150,000 to 300,000, and even more preferably 170,000 to 250,000. If the weight-average molecular weight of polymer (B) is below the upper limit, the second mesh tends to have a densely cross-linked structure, tending to further enhance the cohesive force of the adhesive. Furthermore, if the weight-average molecular weight of polymer (B) is above the lower limit, it tends to interlock with the first mesh, tending to more effectively suppress residual slurry.

[Reactive Functional Group (A1) and Reactive Functional Group (B1)] Examples of the reactive functional group (A1) and the reactive functional group (B1) include a hydroxyl group, a carboxyl group, an amino group, and an epoxy group. Preferably, one of the reactive functional group (A1) and the reactive functional group (B1) is a carboxyl group and the other is a hydroxyl group. More preferably, the reactive functional group (A1) is a carboxyl group and the reactive functional group (B1) is a hydroxyl group.

The functional group equivalent weight of the reactive functional group (A1) of polymer (A) is not particularly limited, but is preferably 500-5,000 g/mol, more preferably 750-3,500 g/mol, and even more preferably 1,000-2,000 g/mol. The functional group equivalent weight of the reactive functional group (B1) of polymer (B) is not particularly limited, but is preferably 500-5,000 g/mol, more preferably 750-3,500 g/mol, and even more preferably 1,000-2,000 g/mol. When the functional group equivalent weights of the reactive functional group (A1) and the reactive functional group (B1) are above the above lower limits, both exhibit good reactivity with the crosslinking agent and tend to form a suitable double network. Furthermore, if the functional group equivalent weight of the reactive functional group (A1) and the reactive functional group (B1) is below the aforementioned upper limit, the number of unreacted reactive functional groups in the adhesive can be reduced, tending to improve quality stability.

[Polymer Type] Preferably, both polymer (A) and polymer (B) are non-energy ray-curable polymers. If polymers (A) and (B) are non-energy ray-curable polymers, it is easier to adjust the adhesive sheet's adhesive force variation rate within the above-mentioned range. Based on the same considerations as above, polymers (A) and (B) preferably do not contain energy ray-polymerizable functional groups. Examples of energy ray-polymerizable functional groups include functional groups containing ethylenically unsaturated bonds, such as (meth)acryloyl, vinyl, and allyl groups.

Examples of polymer (A) and polymer (B) include acrylic polymers, urethane polymers, rubber-based polymers, and polyolefins. Of these, acrylic polymers and urethane polymers are preferred, with acrylic polymers being more preferred. Based on compatibility and other considerations, polymer (A) and polymer (B) are preferably the same type of polymer. Specifically, when polymer (A) is an acrylic polymer, polymer (B) is also preferably an acrylic polymer. Furthermore, when polymer (A) is a urethane polymer, polymer (B) is also preferably a urethane polymer.

Acrylic polymers used as polymers (A) and (B) The acrylic polymers used as polymers (A) and (B) contain units derived from (meth)acrylate esters. The acrylic polymer of polymer (A) (hereinafter also referred to as "acrylic polymer (Aa)") contains units derived from a functional monomer (a1) having a reactive functional group (A1), and is preferably a copolymer containing units derived from an alkyl (meth)acrylate ester. This copolymer may be obtained by copolymerizing monomers other than those listed above, or may be obtained by copolymerizing only the functional monomer (a1) and an alkyl (meth)acrylate ester. The acrylic polymer of polymer (B) (hereinafter also referred to as "acrylic polymer (Ba)") contains units derived from a functional monomer (b1) having a reactive functional group (B1), and is more preferably a copolymer containing units derived from an alkyl (meth)acrylate ester. This copolymer may be obtained by copolymerizing monomers other than those listed above, or by copolymerizing only the functional group monomer (b1) and the (meth)acrylate alkyl ester. The acrylic polymer (Aa) and the acrylic polymer (Ba) may be random copolymers or block copolymers.

Examples of the functional group monomer (a1) and the functional group monomer (b1) include monomers having a hydroxyl group, a carboxyl group, an amino group, an epoxy group, and the like. For each of the functional group monomers (a1) and (b1), one type may be used alone, or two or more types may be used in combination. Among these, it is preferred that one of the functional group monomers (a1) and (b1) is a monomer having a carboxyl group, and the other is a monomer having a hydroxyl group. It is preferred that the functional group monomer (a1) is a monomer having a carboxyl group, and the functional group monomer (b1) is a monomer having a hydroxyl group.

Examples of monomers having a carboxyl group include carboxylic acids having an ethylenically unsaturated bond, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and limonaconic acid. Of these, acrylic acid and methacrylic acid are preferred, with acrylic acid being more preferred. Examples of monomers having a hydroxyl group include hydroxyalkyl (meth)acrylates, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate. Among these, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, with 4-hydroxybutyl (meth)acrylate being more preferred, based on reactivity and copolymerizability with other monomers. In particular, when an acrylic polymer containing units derived from a hydroxyalkyl (meth)acrylate is crosslinked with an isocyanate-based crosslinking agent, 4-hydroxybutyl (meth)acrylate is a preferred monomer having a hydroxy group, as it reacts preferentially with the isocyanate-based crosslinking agent. Based on copolymerizability with other monomers and reactivity with the aforementioned isocyanate-based crosslinking agent, the number of carbon atoms in the hydroxyalkyl group of the hydroxyalkyl (meth)acrylate is preferably 1-10, more preferably 2-8, and even more preferably 3-6.

Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, and stearyl (meth)acrylate. Among these, 2-ethylhexyl (meth)acrylate and n-butyl (meth)acrylate are preferred, and n-butyl (meth)acrylate is more preferred. Alkyl (meth)acrylates may be used alone or in combination of two or more. The number of carbon atoms in the alkyl group of the (meth)acrylate is preferably 1 to 20, more preferably 2 to 10, and even more preferably 4 to 8, from the perspective of achieving better adhesion.

Examples of other monomers include (meth)acrylates having a cyclic skeleton, such as cycloalkyl (meth)acrylates with a cycloalkyl group having 3 to 20 carbon atoms, benzyl (meth)acrylate, and isobornyl (meth)acrylate; vinyl ester compounds such as vinyl acetate and vinyl propionate; alkenes such as ethylene, propylene, and isobutylene; halogenated alkenes such as vinyl chloride and vinylidene chloride; styrene monomers such as styrene and α-methylstyrene; diene monomers such as butadiene, isoprene, and chloroprene; and nitrile monomers such as acrylonitrile and methacrylonitrile. These other monomers may be used alone or in combination.

The content of the constituent units derived from the functional monomer (a1) in the acrylic polymer (Aa) is not particularly limited, but is preferably 0.5-15% by mass, more preferably 1-10% by mass, and even more preferably 3-7% by mass relative to the total weight of the acrylic polymer (Aa). When the content of the constituent units derived from the functional monomer (a1) is at least the lower limit, the reactivity between the acrylic polymer (Aa) and the crosslinking agent (C) is good, and a suitable first mesh tends to be easily formed. Furthermore, when the content of the constituent units derived from the functional monomer (a1) is at most the upper limit, the amount of unreacted reactive functional groups in the adhesive can be reduced, tending to improve quality stability. The content of units derived from alkyl (meth)acrylates in the acrylic polymer (Aa) is not particularly limited, but is preferably 85-99.5% by mass, more preferably 90-99% by mass, and even more preferably 93-97% by mass, relative to the total weight of the acrylic polymer (Aa). A content of units derived from alkyl (meth)acrylates within this range tends to result in better adhesion. The content of units derived from other monomers in the acrylic polymer (Aa) is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, relative to the total weight of the acrylic polymer (Aa).

The content of the constituent units derived from the functional monomer (b1) in the acrylic polymer (Ba) is not particularly limited, but is preferably 0.5-30% by mass, more preferably 1-20% by mass, and even more preferably 5-15% by mass, relative to the total amount of the acrylic polymer (Ba). When the content of the constituent units derived from the functional monomer (b1) is above the lower limit, the reactivity between the acrylic polymer (Ba) and the crosslinking agent (D) is good, and a suitable second mesh tends to be easily formed. Furthermore, when the content of the constituent units derived from the functional monomer (b1) is below the upper limit, unreacted reactive functional groups in the adhesive can be reduced, tending to improve quality stability. The content of units derived from alkyl (meth)acrylates in the acrylic polymer (Ba) is not particularly limited, but is preferably 70-99.5% by mass, more preferably 75-99% by mass, and even more preferably 80-95% by mass, relative to the total weight of the acrylic polymer (Ba). When the content of units derived from alkyl (meth)acrylates is within this range, better adhesion tends to be achieved. The content of units derived from other monomers in the acrylic polymer (Ba) is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 1% by mass or less, relative to the total weight of the acrylic polymer (Ba).

Acrylic polymers (Aa) and (Ba) can be produced, for example, by free radical polymerization of the above-mentioned monomers. Free radical polymerization can be carried out by conventional methods, for example, by solution polymerization using a polymerization initiator as needed. Examples of polymerization initiators include azo compounds and organic peroxides.

Urethane polymers used as polymers (A) and (B) Urethane polymers used as polymers (A) and (B) are polymers containing at least one of urethane and urea bonds. The urethane polymer used as polymer (A) has the aforementioned reactive functional group (A1), such as a polyurethane having a carboxyl group. The urethane polymer used as polymer (B) has the aforementioned reactive functional group (B1), such as a polyurethane having a hydroxyl group.

[Polymer (A) and Polymer (B) Content] The content of polymer (A) in the adhesive composition (P) is not particularly limited, but is preferably 40-95% by weight, more preferably 50-90% by weight, and even more preferably 60-80% by weight, based on the total solids content of the adhesive composition (P). When the polymer (A) content is within this range, excellent flexibility, stretchability, and adhesion derived from the first mesh can be achieved, while also effectively suppressing residual smearing by increasing the frequency of crosstalk with the second mesh.

The content of polymer (B) in the adhesive composition (P) is not particularly limited, but is preferably 5-50% by mass, more preferably 10-40% by mass, and even more preferably 20-30% by mass, based on the total solids content of the adhesive composition (P). Also, the content of polymer (B) in the adhesive composition (P) is not particularly limited, but is preferably 10-80 parts by mass, more preferably 20-60 parts by mass, and even more preferably 30-50 parts by mass, relative to 100 parts by mass of polymer (A). When the content of polymer (B) is within this range, excellent cohesive force is achieved from the second mesh, while the frequency of crosstalk with the first mesh is increased, effectively suppressing residual smearing.

The combined content of polymer (A) and polymer (B) in the adhesive composition (P) is not particularly limited, but is preferably 50-99.5% by mass, more preferably 80-99% by mass, and even more preferably 90-98% by mass, based on the total solids content of the adhesive composition (P). When the combined content of polymer (A) and polymer (B) is within the above range, the effect of enhancing the fracture characteristics of the dual network can be fully demonstrated.

(Crosslinking Agent (C) and Crosslinking Agent (D)) Crosslinking agent (C) is a crosslinking agent for polymer (A) and reacts with reactive functional group (A1). Crosslinking agent (D) is a crosslinking agent for polymer (B) and reacts with reactive functional group (B1). Crosslinking agent (C) and crosslinking agent (D) may be used alone or in combination of two or more.

Crosslinking agent (C) and crosslinking agent (D) are of different types. Crosslinking agent (C) is appropriately selected based on the type of reactive functional group (A1), while crosslinking agent (D) is appropriately selected based on the type of reactive functional group (B1). Furthermore, since crosslinking agent (C) is a crosslinking agent for polymer (A), it is a compound that reacts preferentially with reactive functional group (A1) over reactive functional group (B1). Furthermore, since crosslinking agent (D) is a crosslinking agent for polymer (B), it is a compound that reacts preferentially with reactive functional group (B1) over reactive functional group (A1).

Examples of crosslinking agents (C) and (D) include isocyanate crosslinking agents, epoxy crosslinking agents, amine crosslinking agents, melamine crosslinking agents, azetidine crosslinking agents, hydrazine crosslinking agents, aldehyde crosslinking agents, oxazoline crosslinking agents, metal alkoxide crosslinking agents, metal chelate crosslinking agents, metal salt crosslinking agents, and ammonium salt crosslinking agents. Among these, when the reactive functional group (A1) is a carboxyl group, the crosslinking agent (C) is preferably an epoxy crosslinking agent or a metal chelate crosslinking agent, and more preferably an epoxy crosslinking agent. Furthermore, when the reactive functional group (B1) is a hydroxyl group, the crosslinking agent (D) is preferably an isocyanate crosslinking agent. On the other hand, when the reactive functional group (A1) is a hydroxyl group, the crosslinking agent (C) is preferably an isocyanate crosslinking agent. Furthermore, when the reactive functional group (B1) is a carboxyl group, the crosslinking agent (D) is preferably an epoxy crosslinking agent or a metal chelate crosslinking agent, and more preferably an epoxy crosslinking agent.

Examples of epoxy crosslinking agents include 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane, N,N,N',N'-tetraglycidyl-m-xylenediamine, ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trihydroxymethylpropane diglycidyl ether, diglycidylaniline, and diglycidylamine. Among these, 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane is preferred.

Examples of metal chelate crosslinking agents include compounds such as acetylacetone, ethyl acetylacetate, and tris(2,4-pentanedioate) coordinated to polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium.

Examples of isocyanate crosslinking agents include polyisocyanate compounds. Examples of polyisocyanate compounds include aromatic polyisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate, and xylene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate; and urea compounds, isocyanurate compounds, and adducts thereof. Among these, adducts of polyisocyanate compounds are preferred. Examples of polyisocyanate compound adducts include reaction products of the aforementioned polyisocyanate compounds with low-molecular-weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trihydroxymethylpropane, and castor oil. Among these, polyol adducts of aromatic polyisocyanates such as toluene diisocyanate are preferred, and trihydroxymethylpropane adducts of toluene diisocyanate are more preferred.

(Contents of Crosslinking Agent (C) and Crosslinking Agent (D)) The content of the crosslinking agent (C) in the adhesive composition (P) is not particularly limited, but is preferably 0.005-0.5 parts by mass, more preferably 0.01-0.1 parts by mass, and even more preferably 0.015-0.05 parts by mass per 100 parts by mass of the polymer (A). When the content of the crosslinking agent (C) is above the lower limit, a moderately crosslinked first mesh is formed, which tends to more effectively suppress residual slurry. Furthermore, when the content of the crosslinking agent (C) is below the upper limit, the flexibility and stretchability of the first mesh are enhanced, and the mesh tends to better follow the shape of the workpiece's protrusions and improve the change in adhesion.

The content of the crosslinking agent (D) in the adhesive composition (P) is not particularly limited, but is preferably 1-20 parts by mass, more preferably 2-15 parts by mass, and even more preferably 3-10 parts by mass per 100 parts by mass of the polymer (B). When the crosslinking agent (D) content is above the lower limit, a densely crosslinked second mesh is formed, which tends to more effectively suppress residual slurry. Furthermore, when the crosslinking agent (D) content is below the upper limit, the second mesh exhibits moderate flexibility, tends to follow the contours of the workpiece's protrusions, and tends to exhibit improved changes in adhesion.

Crosslinking of the crosslinking agent (C) and the crosslinking agent (D) is typically performed by heating the adhesive composition (P). Specifically, as described later, the adhesive composition (P) is heated in a thin film state such as by coating, thereby forming an adhesive layer in which the polymer (A) and the polymer (B) are crosslinked by the crosslinking agent (C) and the crosslinking agent (D).

(Other Ingredients) The adhesive composition may contain, as ingredients other than those listed above, adhesion promoters, dyes, pigments, degradation inhibitors, antistatic agents, flame retardants, silane coupling agents, chain transfer agents, plasticizers, fillers, and resin components other than the aforementioned polymers, as long as the effects of the present invention are not impaired. However, the adhesive layer may be free of these ingredients depending on the desired performance. In particular, from the perspective of reducing residual smearing, it is preferred that silane coupling agents be absent. When a silane coupling agent is present, its content is preferably 0.1% by mass or less, more preferably 0.01% by mass or less, and even more preferably 0.001% by mass or less, based on the total solid content of the adhesive composition (P).

The adhesive composition may also contain an organic solvent to facilitate coating during the production of the adhesive sheet. Examples of organic solvents include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, and isopropanol. The organic solvents may be used alone or in combination of two or more.

(Adhesive Layer Thickness) The thickness of the adhesive layer can be adjusted appropriately based on the surface conditions of the workpiece, such as the height of the protrusions on the workpiece, to which the adhesive sheet is attached. To more effectively demonstrate the functionality of the adhesive sheet of this embodiment, the thickness is preferably 10 μm or greater, more preferably 30 μm or greater, and even more preferably 40 μm or greater. Furthermore, for practicality, the thickness of the adhesive layer is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. The thickness of the adhesive layer can be measured using the method described in the Examples.

(Adhesion of Adhesive Sheet) The adhesion force F1 of the adhesive sheet of Test Sheet A of this embodiment, as measured by the peeling test in Method 2 above, is not particularly limited, but is preferably 500-5,000 mN/25 mm, more preferably 1,000-4,800 mN/25 mm, and even more preferably 1,500-4,600 mN/25 mm. Adhesion force F1 above the lower limit tends to improve the protective performance of the adhesive sheet on the workpiece. Furthermore, adhesion force F1 below the upper limit tends to more effectively suppress residual sticking, even when attached to a workpiece having raised portions such as bumps. The adhesive strength of the adhesive layer can be adjusted by adjusting the type and amount of resin that makes up the adhesive layer. For example, increasing the crosslinker content in the adhesive composition (P) tends to reduce the adhesive strength, while decreasing the crosslinker content tends to increase the adhesive strength.

<Release Material> Preferred examples of release materials include release films coated with a release agent on a release material substrate. The release film may be treated on one or both sides. Preferred examples of release material substrates include plastic films. Examples of plastic films include films made of polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; and films made of polyolefin resins such as polypropylene and polyethylene. Examples of stripping agents include rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins; long-chain alkyl resins, alkyd resins, and fluororesins. The thickness of the stripping material is preferably 5 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 50 μm.

<Adhesive Sheet Manufacturing Method> The adhesive sheet of this embodiment can be manufactured by any known method without particular limitation. For example, the adhesive sheet can be manufactured by directly applying an adhesive composition to form an adhesive layer to a substrate and then heating the adhesive layer as needed. Alternatively, the adhesive sheet can be manufactured by applying the adhesive composition to the release-treated surface of a release material to form an adhesive layer, and then attaching the adhesive layer to a substrate. As a method for applying the adhesive composition, known methods can be used, such as spin coating, spray coating, rod coating, knife coating, roller coating, doctor blade coating, die nozzle coating, gravure coating, etc.

When using the adhesive composition (P) as the adhesive composition, it is preferably heated after application. The heating temperature is preferably 80-110°C, more preferably 90-100°C. The heating time is preferably 1-5 minutes, more preferably 2-3 minutes. However, these heating conditions are preferably determined by the types of the components and are not limited to the above ranges.

<Applications of Adhesive Sheets> The adhesive sheet of this embodiment is attached to the surface of a semiconductor device on a workpiece to protect the surface while performing specific processing on the semiconductor device. After the specific processing is completed, the adhesive sheet of this embodiment is peeled off and removed from the semiconductor device. In this specification, the term "semiconductor device" refers to any device that functions by utilizing semiconductor properties, such as semiconductor wafers, semiconductor chips, electronic components containing such semiconductor chips, and electronic devices incorporating such electronic components. Among these, the adhesive sheet of this embodiment is suitable for processing semiconductor wafers.

Examples of processes performed with the adhesive sheet of this embodiment attached include back grinding, where the adhesive sheet is attached to one side of a semiconductor device while the other side is ground; dicing, where the adhesive sheet is attached to one side of a semiconductor device; transporting semiconductor devices; and picking up semiconductor wafers. Among these processes, the adhesive sheet of this embodiment is suitable for back grinding, and is particularly suitable for back grinding, where the adhesive sheet of this embodiment is attached to the circuit-formed side of a semiconductor wafer and the back side of the semiconductor wafer is ground.

The adhesive sheet of this embodiment is preferably used for processing a semiconductor device having a surface with one or more protrusions as an adherend, with an adhesive layer attached to the surface of the semiconductor device having one or more protrusions. As mentioned above, adherends having protrusions are prone to producing residual adhesive because the protrusions are embedded in the adhesive layer of the adhesive sheet. On the other hand, the adhesive sheet of this embodiment exhibits excellent embedding properties and significantly reduces residual adhesive. Therefore, when used on surfaces with one or more protrusions, the adhesive sheet of this embodiment can more effectively demonstrate its functionality. The height of the protrusions is not particularly limited. To more effectively demonstrate the function of the adhesive sheet of this embodiment, it is preferably 10 μm or greater, more preferably 12 μm or greater, and even more preferably 14 μm or greater. The height of the protrusions is not particularly limited and, for example, can be 150 μm or less, 100 μm or less, or even 50 μm or less. The pitch between the protrusions is not particularly limited. To more effectively demonstrate the function of the adhesive sheet of this embodiment, it is preferably 5 to 100 μm, more preferably 10 to 50 μm, and even more preferably 15 to 25 μm. Here, "pitch" refers to the shortest distance between the centers of adjacent protrusions when viewed from above. The top-view shape of the protrusion is not particularly limited, and examples include spheres, cylinders, elliptical cylinders, rotated ellipses, cones, elliptical cones, cubes, rectangular parallelepipeds, trapezoids, and the like. An example of a semiconductor device having a surface with one or more protrusions is a semiconductor wafer having bumps as the protrusions.

[Semiconductor Device Manufacturing Method] The semiconductor device manufacturing method of this embodiment includes the step of processing a semiconductor device having a surface with one or more protrusions having a height of 10 μm or greater. The method involves processing the semiconductor device while affixing the aforementioned adhesive layer of the semiconductor processing adhesive sheet of this embodiment to the surface of the semiconductor device having the one or more protrusions.

The description of a semiconductor device having a surface with one or more protrusions and the description of the semiconductor device and its processing are as described above. Among these, the processing in the semiconductor device manufacturing method of this embodiment is preferably back grinding, in which an adhesive sheet is attached to one surface of the semiconductor device and the other surface is ground. Conventional methods can be used for back grinding. Herein, since the adhesive sheet for semiconductor processing of this embodiment can be peeled from the workpiece without irradiation with energy beams, it is preferably peeled off after processing without irradiation with energy beams. However, "irradiation" here means intentional irradiation with energy beams. [Examples]

The present invention is described in more detail below based on examples, but the present invention is not limited to these examples. The measurement and evaluation methods of various physical properties are as follows.

[Weight Average Molecular Weight (Mw)] The weight average molecular weight (Mw) was measured using a gel permeation chromatography apparatus (manufactured by TOSOH Co., Ltd., product name "HLC-8220") under the following conditions and calculated using standard polystyrene conversion. (Measurement Conditions) • Columns: "TSK Guard Column HXL-H," "TSK Gel GMHXL (×2)," and "TSK Gel G2000HXL" (all manufactured by TOSOH Co., Ltd.) • Column temperature: 40°C • Developing solvent: Tetrahydrofuran • Flow rate: 1.0 mL/min

[Thickness Measurement of Adhesive Sheets, Etc.] The total thickness of the adhesive sheet, the substrate, the adhesive layer, and the test pieces prepared from these were measured using a constant-pressure thickness gauge (manufactured by Teclock Co., Ltd., trade name "PG-02"). Measurements were taken at 10 random points, and the average value was calculated. The total thickness of the adhesive sheet was the thickness of the adhesive sheet with the peel-off film attached, minus the thickness of the peel-off film. The thickness of the adhesive layer was the total thickness of the adhesive sheet minus the thickness of the substrate.

[Method for Determining Fracture Energy] The fracture energy of the adhesive was determined by the following tensile test in accordance with JIS K7127:1999. (1) Preparation of Measurement Samples Five adhesive sheets were prepared by the same method as in Example 1, each having a release film attached to both sides of an adhesive layer having a thickness of 40 μm. The release film on one side was peeled off from two adhesive sheets, and the exposed adhesive layers were stacked on top of each other. By repeating this procedure, five adhesive layers were stacked to prepare an adhesive sheet having a release film attached to both sides of an adhesive layer having a thickness of 0.20 mm. Peel off the films on both sides of the adhesive sheet and cut the adhesive layer into 15mm x 140mm pieces to serve as the tensile test specimens.

(2) Tensile test: Film stretching labels were attached to the 20 mm portion of both ends of the above-mentioned test sample. A tensile test was conducted using a tensile testing machine (manufactured by Shimadzu Corporation, trade name "Autograph AG-IS 1kN") at 23°C, 50% relative humidity, a tensile speed of 200 mm/min, and a chuck distance of 100 mm. A stress-strain curve was plotted from the obtained fracture stress and fracture elongation, and the fracture energy was calculated by calculating the area under the curve. The fracture energy was calculated by averaging the values of three test samples for each level.

[Evaluation of Embedding, Peeling and Residual Properties] (1) Preparation of Evaluation Wafers As the adherend for the peeling test, a wafer with rectangular bumps of 15 μm in height, 20 μm in pitch, and 18 μm in length and 140 μm in width when viewed from above (8-inch wafer manufactured by Well Corporation, bump specification Au = 100% by mass, wafer surface material SiO ₂ ) was prepared. Next, the peeling film was peeled off from the adhesive sheet prepared in each example to prepare an adhesive sheet with the adhesive layer exposed. The adhesive sheet was placed on the wafer with the exposed adhesive layer facing the bump-forming surface of the wafer, and attached at room temperature (23°C) using a lamination machine (manufactured by LINTEC Co., Ltd., product name "RAD-3510F/12") to obtain an evaluation wafer.

(2) Embedment Evaluation The periphery of the bumps on the evaluation wafer was observed using a digital microscope (Keyence Co., Ltd., product name "VHX-1000"), and the embedment of the adhesive sheet was evaluated according to the following evaluation criteria. (Embedment Evaluation Criteria) A: The maximum width of the bumps is less than 10μm. B: The maximum width of the bumps is greater than 10μm.

(3) Peeling test Using a wafer mounter (manufactured by LINTEC Co., Ltd., product name "RAD-2700F/12"), a peeling test of the adhesive sheet on the self-evaluation wafer was conducted at a peeling speed of 4 mm/s. The peeling test was conducted with the stage temperature of the wafer mounter set to room temperature (23°C) and at 40°C.

(4) Evaluation of Releasability Based on the results of the above peeling test, the releasability of the adhesive sheet was evaluated according to the following evaluation criteria. (Evaluation Criteria for Releasability) A: The adhesive sheet was peeled off from the wafer, and no residual adhesive was observed on the wafer. B: Although the adhesive sheet was peeled off from the wafer, residual adhesive was observed on the wafer. C: The adhesive sheet could not be peeled off from the wafer.

(5) Misting evaluation For those with an A or B rating in the above-mentioned peelability evaluation, a mimicking evaluation was performed using the following method. The bump portion of the wafer exposed by peeling the adhesive sheet was observed using a digital microscope (Keyence Co., Ltd., product name "VHX-1000") and a scanning electron microscope (Keyence Co., Ltd., product name "VE-9800"), and the mimicking was evaluated using the following evaluation criteria. The scanning electron microscope can observe finer mimicking than the digital microscope. (Mimicking evaluation criteria) A: No mimicking was observed using either the digital microscope or the scanning electron microscope. B: No blur was observed with a digital microscope, but some blur was observed with a scanning electron microscope. C: Blur was observed with both a digital microscope and a scanning electron microscope.

[Adhesion Force Variation Rate Measurement] The adhesive sheet obtained in each example was evenly cut into 25 mm wide pieces. The peeling film was then removed and temporarily placed on the mirror surface of a silicon mirror wafer, with the adhesive layer forming the mirror side. A 2 kg rubber roller was then applied to the temporarily placed adhesive sheet using a reciprocating motion in accordance with JIS Z0237:2000. The roller's own weight applied a load to the adhesive sheet, thereby attaching the sheet to the silicon mirror wafer. After attachment, the sheet was stored at 23°C and a relative humidity of 50% for 20 minutes. This sample was designated as Test Sheet A. Next, Test Piece A was irradiated with UV light from the adhesive sheet side using a UV irradiation device (manufactured by LINTEC Co., Ltd., trade name "RAD-2000m/12") at an illumination of 220 mW/ ^cm² , a light dose of 560 mJ/ ^cm² , and an irradiation rate of 15 mm/second. The sample was then stored at 23°C and a relative humidity of 50% for 5 minutes, and the resulting sample was designated Test Piece B. The adhesive strength of the adhesive sheet was measured using a tensile testing machine (manufactured by Dongfang Technology Co., Ltd., trade name "Tensilon") at 23°C, a relative humidity of 50%, a peel angle of 180°, and a peel speed of 300 mm/minute. The adhesive force of the adhesive sheet of test piece A is defined as F1, and the adhesive force of the adhesive sheet of test piece B is defined as F2. The change rate of adhesive force before and after UV irradiation is calculated using the following formula (1). Change rate of adhesive force before and after UV irradiation (%) = [(F2-F1)/F1] × 100…(1).

[Adhesive Sheet Production] Adhesive sheets were produced by the following method. In each example, "X/Y/Z = A/B/C" indicating a copolymer composition indicates that the copolymer is a copolymer of monomers X, Y, and Z, obtained by copolymerizing A parts by weight of monomer X, B parts by weight of monomer Y, and C parts by weight of monomer Z. The abbreviations for each monomer are as follows: BA: n-butyl acrylate AA: acrylic acid 4HBA: 4-hydroxybutyl acrylate HEA: 2-hydroxyethyl acrylate MMA: methyl methacrylate

Example 1 (1) Preparation of substrate A double-sided coated PET film (manufactured by Toyobo Co., Ltd., trade name "COSOMO SHINE A4300", thickness: 50 μm, Young's modulus at 23°C: 2,550 MPa, fracture energy: 55.3 MJ/m ³ ) was prepared as a substrate.

(2) Preparation of adhesive composition 100 parts by weight of an acrylic copolymer (composition: BA/AA = 95/5, Mw: 600,000) as polymer (A), 40 parts by weight of an acrylic copolymer (composition: BA/4HBA = 90/10, Mw: 200,000) as polymer (B), 0.019 parts by weight of 1,3-bis(N,N-diglycerylaminomethyl)cyclohexane (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "TETRAD-C", 5% diluted product) as crosslinking agent (C), and 1.000 parts by weight of an isocyanate crosslinking agent (manufactured by TOSOH Co., Ltd., product name "CORNATE The adhesive composition coating liquid was prepared by adding 4.90 parts by mass of methyl ethyl ketone (L") as an organic solvent to a solids concentration of 27% by mass and stirring for 30 minutes. The above amounts refer to the total solids content.

(3) Preparation of Adhesive Sheet The adhesive composition coating liquid obtained above was applied to the release-treated surface of a PET-based release film (manufactured by LINTEC Co., Ltd., trade name "SP-PET381031", thickness 38 μm) using a knife coater. The film was then heated and dried at 100°C for 2 minutes to form an adhesive layer with a thickness of 40 μm on the release film. The adhesive layer was then bonded to one side of the substrate shown above to prepare an adhesive sheet.

Examples 2-5, Comparative Examples 1-4 Adhesive sheets were prepared in the same manner as in Example 1, except that the adhesive composition was changed to that shown in Table 1.

Table 1 shows the evaluation results of the obtained adhesive sheets.

Table 1 shows that the adhesive sheets of Examples 1-5, which had a fracture energy of 7 MJ/ ^m³ or greater, exhibited sufficient embedding properties, suppressing residual sticking when peeled from the workpiece without irradiation. On the other hand, the adhesive sheets of Comparative Examples 1-4, which had a fracture energy of less than 7 MJ/ ^m³ , could not be peeled under the peeling test conditions, or even if peeled, residual sticking was insufficiently suppressed.

Claims (8)

An adhesive sheet for semiconductor processing comprises a substrate and an adhesive layer disposed on one surface of the substrate; the adhesive constituting the adhesive layer has a fracture energy of 7 MJ/m as measured by a tensile test according to the following method 1. ³ or more; the adhesive layer is formed by an adhesive composition, the adhesive composition comprising: a polymer (A) having a reactive functional group (A1), a polymer (B) having a reactive functional group (B1) different from the reactive functional group (A1) and having a weight average molecular weight lower than that of the polymer (A), a crosslinking agent (C) reactive with the reactive functional group (A1), and a crosslinking agent (D) reactive with the reactive functional group (B1) and different from the crosslinking agent (C); the weight average molecular weight of the polymer (A) is 400,000 to 1,000,000, and the weight average molecular weight of the polymer (B) is 120,0 00 to 350,000; the amount of the polymer (B) is 10 to 80 parts by mass relative to 100 parts by mass of the polymer (A); the adhesive sheet has an adhesive strength change rate before and after ultraviolet irradiation of -10 to +10% as measured by the peeling test of Method 2 below; (Method 1) a test piece having a thickness of 0.20 mm, a width of 15 mm, and a length of 140 mm is prepared from the adhesive constituting the adhesive layer. The test piece is subjected to a tensile test at 23°C, a relative humidity of 50%, a tensile speed of 200 mm/min, and a point spacing of 100 mm to measure the fracture energy; (Method 2) A 25mm wide adhesive sheet was prepared so that the adhesive layer became the adhesive surface. Based on JIS Z0237:2000, the adhesive sheet was attached to the mirror surface of a silicon mirror wafer using a 2kg rubber roller. The sheet was then stored in an environment at 23°C and a relative humidity of 50% for 20 minutes. The sample was designated as Test Piece A. The test piece A was subjected to a 220mW/ ^cm2 illumination and a 560mJ/cm2 light intensity test from the adhesive sheet side. ² , and then stored at 23°C and 50% relative humidity for 5 minutes as test piece B; using test pieces A and B, the peeling test of the adhesive sheet was carried out under the conditions of 23°C, 50% relative humidity, a peeling angle of 180°, and a peeling speed of 300 mm/min; the adhesive force F1 of the adhesive sheet of test piece A and the adhesive force F2 of the adhesive sheet of test piece B were respectively calculated, and the adhesive force change rate before and after ultraviolet irradiation was calculated by the following formula (1); the adhesive force change rate before and after ultraviolet irradiation (%) = [(F2-F1)/F1]×100...(1). The adhesive sheet for semiconductor processing according to claim 1, wherein the thickness of the adhesive layer is greater than 40 μm. The adhesive sheet for semiconductor processing according to claim 1 or 2, wherein the adhesive force F1 of the adhesive sheet of test piece A measured by the peeling test of method 2 is 500-5,000 mN/25 mm. In the adhesive sheet for semiconductor processing according to claim 1 or 2, the polymer (A) and the polymer (B) are both non-energy ray-curable polymers. In the adhesive sheet for semiconductor processing according to claim 1 or 2, the functional group equivalent weight of the reactive functional group (B1) in the polymer (B) is 500 to 5,000 g/mol. The adhesive sheet for semiconductor processing according to claim 1 or 2, wherein the reactive functional group (A1) is a carboxyl group, the reactive functional group (B1) is a hydroxyl group, the crosslinking agent (C) is an epoxy crosslinking agent, and the crosslinking agent (D) is an isocyanate crosslinking agent; or wherein the reactive functional group (A1) is a hydroxyl group, the reactive functional group (B1) is a carboxyl group, the crosslinking agent (C) is an isocyanate crosslinking agent, and the crosslinking agent (D) is an epoxy crosslinking agent. The adhesive sheet for semiconductor processing according to claim 1 or 2 is used as follows: a semiconductor device having a surface with one or more protrusions having a height of 10 μm or greater is used as an adherend, and the adhesive layer is affixed to the surface of the semiconductor device having the one or more protrusions, and the semiconductor device is processed. A method for manufacturing a semiconductor device comprises processing a semiconductor device having a surface with one or more protrusions having a height of 10 μm or greater; the semiconductor device is processed while the adhesive layer of the semiconductor processing adhesive sheet according to any one of claims 1 to 7 is affixed to the surface of the semiconductor device having the one or more protrusions.