Method of manufacturing a semiconductor device

Abstract

The present invention relates to a method of manufacturing a semiconductor device using an adhesive sheet having, in the following order, an adhesive layer (X1) containing heat-expandable particles, a base material (Y), and an adhesive layer (X2) that is hardened by being irradiated with energy rays and thus has decreased adhesive force, the method comprising specific steps 1 to 5.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a semiconductor device.

Background Art

[0002] In recent years, electronic devices have been miniaturized, lightweighted, and highly functionalized. Along with this, semiconductor devices mounted on electronic devices are also required to be miniaturized, thinned, and highly densified. In the manufacturing process of a semiconductor device, a semiconductor wafer is processed into semiconductor chips through a grinding process of thinning the thickness by grinding, a singulation process of cutting and separating into individual pieces, etc. At this time, the semiconductor wafer is subjected to predetermined processing in a state of being temporarily fixed to a temporary fixing sheet. After the semiconductor chips obtained by the predetermined processing are separated from the temporary fixing sheet, if necessary, an expand process of widening the interval between the semiconductor chips, a rearrangement process of arranging a plurality of semiconductor chips with widened intervals, an inversion process of inverting the front and back of the semiconductor chips, etc. are appropriately performed, and then they are mounted on a substrate.

[0003] When mounting a semiconductor chip on a substrate, a process of attaching the semiconductor chip to the substrate via a film-like adhesive having thermosetting properties, called a die attach film (hereinafter also referred to as "DAF"), is adopted. The DAF is attached to one surface of a semiconductor wafer or a plurality of singulated semiconductor chips, and is divided into the same shape as the semiconductor chips simultaneously with the singulation of the semiconductor wafer or after being attached to the semiconductor chips. The semiconductor chip with DAF obtained by singulation is attached (die attach) to the substrate from the DAF side, and then the semiconductor chip and the substrate are fixed by thermosetting the DAF. Therefore, until the DAF is attached to the substrate, it is necessary to maintain the property of adhering by pressure or heating, and a process that enables this is required.

[0004] In order to improve the processing accuracy and processing speed when grinding or singulating an object to be processed such as a semiconductor wafer, it is necessary to suppress vibrations, positional deviations, etc. of the object to be processed during processing by using fixing means such as a temporary fixing sheet. On the other hand, after the processing is completed, from the viewpoint of enhancing productivity, the object to be processed is required to be quickly separated from the fixing means. Patent Document 1 discloses a method of using a heat-expandable pressure-sensitive adhesive sheet provided with a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres on at least one side of a base material for cutting electronic components. The document states that the heat-expandable pressure-sensitive adhesive sheet can exhibit an adhesiveness capable of preventing adhesion failures such as chip jumping because it can secure a contact area of a predetermined size with the adherend during the cutting of electronic components. On the other hand, after use, it is described that by heating to expand the heat-expandable microspheres, the contact area with the adherend can be reduced and it can be easily peeled off.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when fixing and cutting an object to be processed to a heat-expandable pressure-sensitive adhesive layer as in the method disclosed in Patent Document 1, there is a concern that residues derived from the heat-expandable particles may adhere to the surface of the object to be processed after peeling by heating, or the pressure-sensitive adhesive layer may be deformed or deteriorated due to the expansion of the heat-expandable particles, and a part of the pressure-sensitive adhesive layer may adhere to the surface of the object to be processed (so-called "adhesive residue"), contaminating the surface of the object to be processed.

[0007] The present invention has been made in view of the above problems, and an object thereof is to provide a method for manufacturing a semiconductor device that has no concern about contamination of an object to be processed by heat-expandable particles and an expanded pressure-sensitive adhesive layer, and is excellent in processability and productivity.

Means for Solving the Problems

[0008] The inventors of the present invention have found that the above problems can be solved by a method for manufacturing a semiconductor device using an adhesive sheet having, in this order, an adhesive layer containing thermally expandable particles, a base material, and an adhesive layer that is cured by irradiation with energy rays and has a reduced adhesive force, and including specific steps 1 to 5. That is, the present invention relates to the following [1] to

[10] . [1] A method for manufacturing a semiconductor device using an adhesive sheet having, in this order, an adhesive layer (X1) containing thermally expandable particles, a base material (Y), and an adhesive layer (X2) that is cured by irradiation with energy rays and has a reduced adhesive force, the method for manufacturing a semiconductor device including the following steps 1 to 5. Step 1: A step of attaching an object to be processed to the adhesive layer (X2) of the adhesive sheet and attaching a support to the adhesive layer (X1) of the adhesive sheet. Step 2: A step of performing one or more processing operations selected from grinding processing and singulation processing on the object to be processed. Step 3: A step of attaching a thermosetting film to the surface of the processed object opposite to the adhesive layer (X2) after the processing operation. Step 4: A step of heating the adhesive sheet to separate the adhesive layer (X1) from the support. Step 5: A step of irradiating the adhesive layer (X2) with energy rays to separate the adhesive layer (X2) from the object to be processed. [2] The method for manufacturing a semiconductor device according to the above [1], wherein the processing operation is a singulation processing by a stealth dicing method, a grinding processing and a singulation processing by a blade tip dicing method, or a grinding processing and a singulation processing by a stealth tip dicing method. [3] The method for manufacturing a semiconductor device according to the above [1] or [2], wherein the processing operation is a grinding processing and a singulation processing by a stealth tip dicing method. [4] The method for manufacturing a semiconductor device according to any one of the above [1] to [3], wherein the expansion start temperature (t) of the thermally expandable particles is 50 to 110°C. [5] The method for manufacturing a semiconductor device according to [4] above, wherein the step 4 is a step of heating the pressure-sensitive adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) of the thermally expandable particles and equal to or lower than 120 °C to separate the pressure-sensitive adhesive layer (X1) from the support. [6] The method for manufacturing a semiconductor device according to any one of [1] to [5] above, wherein the content of the thermally expandable particles is 1 to 30% by mass based on the total mass (100% by mass) of the pressure-sensitive adhesive layer (X1). [7] The average particle diameter (D 50 ) of the thermally expandable particles at 23 °C is 1 to 30 μm, and the method for manufacturing a semiconductor device according to any one of [1] to [6] above. [8] The storage elastic modulus E'(23) of the base material (Y) at 23 °C is 5.0×10 7 ~5.0×10 9 Pa, and the method for manufacturing a semiconductor device according to any one of [1] to [7] above. [9] The method for manufacturing a semiconductor device according to any one of [1] to [8] above, wherein the object to be processed is a semiconductor wafer.

[10] The method for manufacturing a semiconductor device according to any one of [1] to [9] above, wherein the energy ray is ultraviolet light. [Advantages of the Invention]

[0009] According to the present invention, it is possible to provide a method for manufacturing a semiconductor device that has no concern about contamination of the object to be processed by the thermally expandable particles and the expanded pressure-sensitive adhesive layer, and is excellent in processability and productivity. [Brief Description of the Drawings]

[0010]

Figure 1

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Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0011] In this specification, the “active ingredient” refers to the component excluding the diluent solvent among the components contained in the target composition. Also, in this specification, the mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by gel permeation chromatography (GPC) method, specifically, a value measured based on the method described in the examples.

[0012] In this specification, for example, “(meth)acrylic acid” means both “acrylic acid” and “methacrylic acid”, and the same applies to other similar terms. Also, in this specification, for preferable numerical ranges (for example, ranges such as content), the lower limit value and the upper limit value described stepwise can be combined independently. For example, from the description “preferably 10 to 90, more preferably 30 to 60”, it is also possible to combine the “preferable lower limit value (10)” and the “more preferable upper limit value (60)” to obtain “10 to 60”.

[0013] In this specification, the “energy ray” means those having energy quanta among electromagnetic waves or charged particle beams, and examples thereof include ultraviolet rays, radiation, electron beams, etc. Ultraviolet rays can be irradiated, for example, by using an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, etc. as an ultraviolet ray source. Electron beams can be irradiated with those generated by an electron beam accelerator or the like. In this specification, "energy ray polymerizability" means the property of polymerizing by irradiating with energy rays.

[0014] In this specification, whether a "layer" is a "non-thermally expandable layer" or a "thermally expandable layer" is determined as follows. When the layer to be judged contains thermally expandable particles, the layer is heat-treated at the expansion start temperature (t) of the thermally expandable particles for 3 minutes. When the volume change rate calculated from the following formula is less than 5%, the layer is judged to be a "non-thermally expandable layer", and when it is 5% or more, the layer is judged to be a "thermally expandable layer". · Volume change rate (%) = {(volume of the layer after heat treatment - volume of the layer before heat treatment) / volume of the layer before heat treatment} × 100 Note that a layer that does not contain thermally expandable particles is regarded as a "non-thermally expandable layer".

[0015] In this specification, the "surface" of a semiconductor wafer and a semiconductor chip refers to the surface on which a circuit is formed (hereinafter also referred to as the "circuit surface"), and the "back surface" of a semiconductor wafer and a semiconductor chip refers to the surface on which no circuit is formed.

[0016] [Method for manufacturing a semiconductor device] A method for manufacturing a semiconductor device according to one aspect of the present invention is a method for manufacturing a semiconductor device using an adhesive sheet having, in this order, an adhesive layer (X1) containing thermally expandable particles, a base material (Y), and an adhesive layer (X2) that cures by irradiating with energy rays and has a reduced adhesive force, and includes the following steps 1 to 5. Step 1: A step of attaching an object to be processed to the adhesive layer (X2) of the adhesive sheet and attaching a support to the adhesive layer (X1) of the adhesive sheet. Step 2: A step of performing one or more processing steps selected from grinding processing and singulation processing on the object to be processed. Step 3: A step of attaching a thermosetting film to the surface of the object to be processed on the side opposite to the adhesive layer (X2) after the processing step. Step 4: A step of heating the adhesive sheet to separate the adhesive layer (X1) and the support. Step 5: irradiating the adhesive layer (X2) with energy rays to separate the adhesive layer (X2) from the object to be processed

[0017] Here, in this specification, the "semiconductor device" refers to all devices that can function by utilizing semiconductor characteristics. For example, a wafer with an integrated circuit, a thinned wafer with an integrated circuit, a chip with an integrated circuit, a thinned chip with an integrated circuit, electronic components including these chips, and electronic devices including such electronic components, etc. can be mentioned. In addition, as the "object to be processed" on which processing is performed in the method for manufacturing a semiconductor device according to one aspect of the present invention, typically a semiconductor wafer and a semiconductor chip can be mentioned, but it is not particularly limited as long as it can apply the manufacturing method of the present invention.

[0018] According to the method for manufacturing a semiconductor device according to one aspect of the present invention, the object to be processed is processed in a state where it is attached to an adhesive layer (X2) that is cured by irradiating with energy rays and has a reduced adhesive force. According to this method, after the processing, the object to be processed can be separated from the adhesive sheet by irradiating the adhesive layer (X2) with energy rays, so the object to be processed is not contaminated by the thermally expandable particles and the expanded adhesive layer.

[0019] In addition, according to the method for manufacturing a semiconductor device according to one aspect of the present invention, when performing a processing operation on the object to be processed, a support is attached to the adhesive layer (X1) containing thermally expandable particles. When the adhesive layer (X1) is heated to a temperature equal to or higher than the expansion start temperature (t) of the thermally expandable particles, unevenness due to the expanded thermally expandable particles is formed on the surface, and the contact area with the adherend decreases. Due to the decrease in the contact area, the adhesion between the adhesive layer (X1) and the adherend is significantly reduced, and without applying a peeling force, the adhesive sheet and the support can be quickly separated by the self-weight on the adhesive sheet side or the self-weight of the adherend. For example, when peeling by heating, by turning the adhesive sheet to which the object to be processed is attached downward, the adhesive sheet to which the object to be processed is attached can be dropped from the support by gravity and separated. Thus, since the adhesive layer (X1) can significantly reduce its adhesion to the support by heating, the adhesion before heat peeling can be designed to be high. Therefore, according to the method for manufacturing a semiconductor device according to one aspect of the present invention, vibrations, positional deviations, etc. of the object to be processed due to insufficient adhesion between the adhesive sheet and the support can be suppressed, and excellent processing accuracy and processing speed can be obtained. In this specification, "self - peeling" is defined as a state in which the adhesive sheet peels off or detaches from the adherend without applying a force to peel the adhesive sheet. Further, such a property is referred to as "self - peeling property".

[0020] First, the adhesive sheet used in the method for manufacturing a semiconductor device according to one aspect of the present invention will be described, and then each step included in the method for manufacturing a semiconductor device according to one aspect of the present invention will be described in detail.

[0021] [Adhesive Sheet] The adhesive sheet used in one aspect of the present invention is an adhesive sheet having, in this order, an adhesive layer (X1) containing thermally expandable particles, a base material (Y), and an adhesive layer (X2) that cures by irradiating energy rays and has a reduced adhesive force. The adhesive sheet used in one aspect of the present invention may have a release material on one or both adhesive surfaces of the adhesive layer (X1) and the adhesive layer (X2).

[0022] Next, with reference to the drawings, the configuration of the adhesive sheet used in one aspect of the present invention will be described more specifically.

[0023] Examples of the adhesive sheet used in one aspect of the present invention include a double - sided adhesive sheet 1a having a configuration in which a base material (Y) is sandwiched between an adhesive layer (X1) and an adhesive layer (X2), as shown in FIG. 1(a). Also, like the double - sided adhesive sheet 1b shown in FIG. 1(b), it may have a configuration in which a release material 10a is further provided on the adhesive surface of the adhesive layer (X1) and a release material 10b is further provided on the adhesive surface of the adhesive layer (X2).

[0024] In the double-sided adhesive sheet 1b shown in FIG. 1(b), when the release force when peeling the release material 10a from the adhesive layer (X1) is approximately the same as the release force when peeling the release material 10b from the adhesive layer (X2), if both release materials are pulled outward to peel them, there may occur a phenomenon in which the adhesive layer is separated and peeled off along with the two release materials. From the viewpoint of suppressing such a phenomenon, it is preferable to use two types of release materials designed such that the release forces from the adhesive layers to which the two release materials are attached to each other are different.

[0025] As another aspect of the adhesive sheet, in the double-sided adhesive sheet 1a shown in FIG. 1(a), a double-sided release-treated release material may be laminated on one adhesive surface of the adhesive layer (X1) and the adhesive layer (X2), and it may be a double-sided adhesive sheet having a configuration wound in a roll shape.

[0026] The adhesive sheet used in one aspect of the present invention may or may not have another layer between the base material (Y) and the adhesive layer (X1). Also, the adhesive sheet used in one aspect of the present invention may or may not have another layer between the base material (Y) and the adhesive layer (X2). However, it is preferable that a layer capable of suppressing expansion on the surface is directly laminated on the surface opposite to the adhesive surface of the adhesive layer (X1), and it is more preferable that the base material (Y) is directly laminated.

[0027] <Base material (Y)> Examples of the material for forming the base material (Y) include resins, metals, paper materials, etc., and can be appropriately selected according to the use of the adhesive sheet used in one aspect of the present invention.

[0028] Examples of the resin include polyolefin resins such as polyethylene and polypropylene; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; urethane resins such as polyurethane and acrylic-modified polyurethane; polymethylpentene; polysulfone; polyetheretherketone; polyethersulfone; polyphenylene sulfide; polyimide resins such as polyetherimide and polyimide; polyamide resins; acrylic resins; and fluorine-based resins. Examples of the metal include aluminum, tin, chromium, and titanium. Examples of the paper material include tissue paper, medium-quality paper, high-quality paper, impregnated paper, coated paper, art paper, sulfuric acid paper, and glassine paper. Among these, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferred.

[0029] These forming materials may be composed of one type or used in combination of two or more types. Examples of the base material (Y) obtained by using a combination of two or more forming materials include those obtained by laminating a paper material with a thermoplastic resin such as polyethylene, and those obtained by forming a metal layer on the surface of a resin film or sheet containing a resin. Examples of the method for forming the metal layer include a method of depositing a metal by a PVD method such as vacuum evaporation, sputtering, and ion plating, and a method of attaching a metal foil using a general adhesive.

[0030] From the viewpoint of improving the interlayer adhesion between the base material (Y) and another layer to be laminated, the surface of the base material (Y) may be subjected to surface treatment such as an oxidation method and an unevenness method, an easy adhesion treatment, a primer treatment, etc. Examples of the acidification method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone irradiation treatment, ultraviolet irradiation treatment, and the like. Examples of the roughening method include sandblasting method, solvent treatment method, and the like.

[0031] The base material (Y) may contain, as an additive for the base material, for example, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an antiblocking agent, a colorant, etc. together with the above resin. These additives for the base material may be used alone or in combination of two or more. When the base material (Y) contains an additive for the base material together with the above resin, the content of each additive for the base material is preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass, based on 100 parts by mass of the above resin.

[0032] The base material (Y) is preferably a non-thermally expandable layer. When the base material (Y) is a non-thermally expandable layer, the volume change rate (%) of the base material (Y) calculated from the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, still more preferably less than 0.1%, and even more preferably less than 0.01%.

[0033] The base material (Y) may contain thermally expandable particles within a range not contrary to the object of the present invention, but preferably does not contain thermally expandable particles. When the base material (Y) contains thermally expandable particles, the lower the content, the more preferable. Based on the total mass (100% by mass) of the base material (Y), it is preferably less than 3% by mass, more preferably less than 1% by mass, still more preferably less than 0.1% by mass, even more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass.

[0034] 〔Physical properties of the base material (Y), etc.〕 (Storage elastic modulus E'(23) of the base material (Y) at 23°C) The storage elastic modulus E'(23) of the base material (Y) at 23°C is preferably 5.0×10 7 ~5.0×10 9Pa, more preferably 5.0×10 8 ~4.5×10 9 Pa, still more preferably 1.0×10 9 ~4.0×10 9 Pa. If the storage elastic modulus E’(23) of the base material (Y) is 5.0×10 7 Pa or more, the expansion of the surface on the base material (Y) side of the adhesive layer (X1) can be effectively suppressed, and the deformation resistance of the adhesive sheet can be improved. On the other hand, if the storage elastic modulus E’(23) of the base material (Y) is 5.0×10 9 Pa or less, the handleability of the adhesive sheet can be improved. In this specification, the storage elastic modulus E’(23) of the base material (Y) means the value measured by the method described in the examples.

[0035] (Storage elastic modulus E’(t) of the base material (Y) at the expansion start temperature (t)) The storage elastic modulus E’(t) of the base material (Y) at the expansion start temperature (t) of the thermally expandable particles is preferably 5.0×10 6 ~4.0×10 9 Pa, more preferably 2.0×10 8 ~3.0×10 9 Pa, still more preferably 5.0×10 8 ~2.5×10 9 Pa. If the storage elastic modulus E’(t) of the base material (Y) is 5.0×10 6 Pa or more, the expansion of the surface on the base material (Y) side of the adhesive layer (X1) can be efficiently suppressed, and the deformation resistance of the adhesive sheet can be improved. On the other hand, if the storage elastic modulus E’(t) of the base material (Y) is 4.0×10 9 Pa or less, the handleability of the adhesive sheet can be improved. In this specification, the storage elastic modulus E’(t) of the base material (Y) means the value measured by the method described in the examples.

[0036] (Thickness of the base material (Y)) The thickness of the base material (Y) is preferably 5 to 500 μm, more preferably 15 to 300 μm, still more preferably 20 to 200 μm. If the thickness of the base material (Y) is 5 μm or more, the deformation resistance of the pressure-sensitive adhesive sheet can be improved. On the other hand, if the thickness of the base material (Y) is 500 μm or less, the handleability of the pressure-sensitive adhesive sheet can be improved. In addition, in this specification, the thickness of the base material (Y) means the value measured by the method described in the examples.

[0037] <Adhesive layer (X1)> The adhesive layer (X1) is an adhesive layer containing thermally expandable particles. The adhesive layer (X1) is a layer that, when heated to a temperature equal to or higher than the expansion start temperature (t) of the thermally expandable particles, forms irregularities on the surface due to the expanded thermally expandable particles, and can reduce the adhesion to the adherend. Hereinafter, each component contained in the adhesive layer (X1) will be described.

[0038] 〔Thermally expandable particles〕 The expansion start temperature (t) of the thermally expandable particles contained in the adhesive layer (X1) is not particularly limited and may be appropriately adjusted according to the use of the pressure-sensitive adhesive sheet. For example, from the viewpoint of suppressing the expansion of the thermally expandable particles due to the temperature rise when grinding the object to be processed, etc., it is preferably 50 °C or higher, more preferably 55 °C or higher, still more preferably 60 °C or higher, and even more preferably 70 °C or higher. On the other hand, from the viewpoint of suppressing the curing of the thermosetting film attached to the object to be processed during heat peeling, it is preferably 110 °C or lower, more preferably 105 °C or lower, still more preferably 100 °C or lower, and even more preferably 95 °C or lower. In addition, in this specification, the expansion start temperature (t) of the thermally expandable particles means the value measured based on the following method. [Measurement method of the expansion start temperature (t) of thermally expandable particles] Prepare a sample by adding 0.5 mg of the thermally expandable particles to be measured into an aluminum cup with a diameter of 6.0 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, and placing an aluminum lid (diameter 5.6 mm, thickness 0.1 mm) on it. Using a dynamic viscoelasticity measuring device, the height of the sample is measured while applying a force of 0.01 N to the sample from above the aluminum lid using a pressure head. Then, while applying a force of 0.01 N with the pressure head, it is heated at a temperature increase rate of 10 °C / min from 20 °C to 300 °C, and the displacement amount in the vertical direction of the pressure head is measured. The temperature at which displacement starts in the positive direction is defined as the expansion start temperature (t).

[0039] The thermally expandable particles are preferably a microencapsulated blowing agent composed of an outer shell made of a thermoplastic resin and an encapsulated component encapsulated in the outer shell and vaporizing when heated to a predetermined temperature. The thermoplastic resin constituting the outer shell of the microencapsulated blowing agent is not particularly limited, and materials and compositions that can cause state changes such as melting, dissolution, and rupture at the expansion start temperature (t) of the thermally expandable particles may be appropriately selected. Examples of the thermoplastic resin include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, etc. These thermoplastic resins may be used alone or in combination of two or more.

[0040] As the encapsulated component, which is the component encapsulated in the outer shell of the microencapsulated blowing agent, any component that expands at the expansion start temperature (t) of the thermally expandable particles may be used. Examples include propane, propylene, n-butane, butene, n-pentane, n-hexane, n-heptane, n-octane, n-nonane, n-decane, isobutane, isopentane, isohexane, isoheptane, isooctane, isononane, isodecane, cyclopropane, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, neopentane, dodecane, isododecane, cyclotridecane, hexylcyclohexane, tridecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, isotridecane, 4-methyldodecane, isotetradecane, isopentadecane, isohexadecane, 2,2,4,4,6,8,8-heptamethylnonane, isoheptadecane, isooctadecane, isononadecane, 2,6,10,14-tetramethylpentadecane, cyclotridecane, heptylcyclohexane, n-octylcyclohexane, cyclopentadecane, nonylcyclohexane, decylcyclohexane, pentadecylcyclohexane, hexadecylcyclohexane, heptadecylcyclohexane, octadecylcyclohexane, petroleum ether, and the like. Among these, from the viewpoint of lowering the expansion start temperature (t) and suppressing the curing of the thermosetting film attached to the object to be processed when peeling the adhesive layer (X1) by heating, low-boiling liquids such as propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, n-heptane, n-octane, cyclopropane, cyclobutane, and petroleum ether are preferable. These encapsulated components may be used alone or in combination of two or more. The expansion start temperature (t) of the thermally expandable particles can be adjusted by appropriately selecting the type of the encapsulated component.

[0041] The average particle diameter (D 50 ) of the thermally expandable particles before thermal expansion at 23°C is preferably 1 to 30 μm, more preferably 4 to 25 μm, still more preferably 6 to 20 μm, and even more preferably 10 to 15 μm. The average particle diameter (D 50 ) of the thermally expandable particles is the volume median particle diameter (D 50 ). In the particle size distribution of the thermally expandable particles before expansion measured using a laser diffraction particle size distribution analyzer (for example, manufactured by Malvern, product name "Master Sizer 3000"), it means the particle diameter corresponding to a cumulative volume frequency of 50% calculated from the smaller particle diameters.

[0042] The 90% particle diameter (D 90 ) of the thermally expandable particles at 23°C before thermal expansion is preferably 2 to 60 μm, more preferably 8 to 50 μm, still more preferably 12 to 40 μm, and even more preferably 20 to 30 μm. The 90% particle diameter (D 90 ) of the thermally expandable particles means the particle diameter corresponding to a cumulative volume frequency of 90% calculated from the smaller particle diameters in the particle size distribution of the thermally expandable particles before expansion measured using the above laser diffraction particle size distribution analyzer.

[0043] The maximum volume expansion ratio when the thermally expandable particles are heated to a temperature equal to or higher than the expansion start temperature (t) is preferably 1.5 to 200 times, more preferably 2 to 150 times, still more preferably 2.5 to 120 times, and even more preferably 3 to 100 times.

[0044] The content of the thermally expandable particles is preferably 1 to 30% by mass, more preferably 2 to 25% by mass, and still more preferably 3 to 20% by mass with respect to the total mass (100% by mass) of the pressure-sensitive adhesive layer (X1). When the content of the thermally expandable particles is 1% by mass or more, the peelability at the time of heat peeling tends to improve. Further, when the content of the thermally expandable particles is 30% by mass or less, the adhesive strength of the pressure-sensitive adhesive layer (X1) is improved, and curling of the adhesive sheet at the time of heat peeling is suppressed, and the handleability tends to be improved.

[0045] 〔Pressure-sensitive adhesive resin〕 The pressure-sensitive adhesive resin contained in the pressure-sensitive adhesive layer (X1) can be selected according to the method for forming the pressure-sensitive adhesive layer (X1). In the present invention, the term "adhesive resin" broadly includes resins that do not have adhesiveness in a composition substantially composed only of an adhesive resin but exhibit adhesiveness by adding a plasticizing component or the like.

[0046] As a method for forming the adhesive layer (X1), there are a method of irradiating a polymerizable composition containing an energy ray-polymerizable component and thermally expandable particles (hereinafter also referred to as "polymerizable composition (x-1A)") with an energy ray to form an adhesive layer (X1) containing a polymer of the energy ray-polymerizable component and thermally expandable particles, a method of applying an adhesive composition containing an adhesive resin and thermally expandable particles (hereinafter also referred to as "adhesive composition (x-1B)") to form the adhesive layer (X1), and the like. Next, suitable embodiments of the adhesive resin in the method using the polymerizable composition (x-1A) and the method using the adhesive composition (x-1B) will be described respectively.

[0047] - Method using the polymerizable composition (x-1A)- The method using the polymerizable composition (x-1A) is a method of irradiating a polymerizable composition (x-1A) containing an energy ray-polymerizable component and thermally expandable particles with an energy ray to form an adhesive layer (X1) containing a polymer of the energy ray-polymerizable component and thermally expandable particles. Therefore, according to this method, the adhesive resin contained in the adhesive layer (X1) is a polymer obtained by polymerizing the energy ray-polymerizable component contained in the polymerizable composition (x-1A) with an energy ray. Since the coincidence composition (x-1A) is to increase the molecular weight of the energy ray-polymerizable component by subsequent energy ray polymerization, when forming a layer, it may contain a low molecular weight energy ray-polymerizable component. Therefore, the polymerizable composition (x-1A) can be adjusted to a viscosity suitable for coating without using a solvent such as a diluent. As a result, when forming the pressure-sensitive adhesive layer (X1) using the polymerizable composition (x-1A), heating and drying for removing the solvent can be omitted, and unintentional expansion of the thermally expandable particles during heating and drying can be suppressed. Further, since it is not necessary to adjust the expansion start temperature (t) of the thermally expandable particles to be equal to or higher than the heating and drying temperature, the expansion start temperature (t) of the thermally expandable particles can be lowered, and even when a heat-sensitive object such as a semiconductor chip with DAF is used as an adherend, thermal change of the adherend due to heating during heat peeling can be suppressed.

[0048] The energy ray-polymerizable component contained in the polymerizable composition (x-1A) is a component that polymerizes by irradiation with energy rays and has an energy ray-polymerizable functional group. Examples of the energy ray-polymerizable functional group include those having a carbon-carbon double bond such as a (meth)acryloyl group, a vinyl group, and an allyl group. In this specification, functional groups containing a vinyl group or a substituted vinyl group in part, such as a (meth)acryloyl group and an allyl group, and the vinyl group or the substituted vinyl group itself may be collectively referred to as a "vinyl group-containing group".

[0049] The polymerizable composition (x-1A) preferably contains, as the energy ray-polymerizable component, a monomer (a1) having an energy ray-polymerizable functional group (hereinafter also referred to as the "(a1) component") and a prepolymer (a2) having an energy ray-polymerizable functional group (hereinafter also referred to as the "(a2) component"). In this specification, a prepolymer means a compound formed by polymerization of monomers and capable of constituting a polymer by further polymerization.

[0050] (Monomer (a1) having an energy ray-polymerizable functional group) As the monomer (a1) having an energy ray-polymerizable functional group, any monomer having an energy ray-polymerizable functional group may be used. In addition to the energy ray-polymerizable functional group, it may also have a hydrocarbon group, a functional group other than the energy ray-polymerizable functional group, and the like.

[0051] Examples of the hydrocarbon group contained in the component (a1) include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and a group combining these. The aliphatic hydrocarbon group may be a linear or branched aliphatic hydrocarbon group or an alicyclic hydrocarbon group. Examples of the linear or branched aliphatic hydrocarbon group include aliphatic hydrocarbon groups having 1 to 20 carbon atoms such as methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, sec-butyl group, n-pentyl group, n-hexyl group, 2-ethylhexyl group, n-octyl group, isooctyl group, n-decyl group, n-dodecyl group, n-myristyl group, n-palmityl group, and n-stearyl group. Examples of the alicyclic hydrocarbon group include alicyclic hydrocarbon groups having 3 to 20 carbon atoms such as cyclopentyl group, cyclohexyl group, and isobornyl group. Examples of the aromatic hydrocarbon group include phenyl group. Examples of the group combining an aliphatic hydrocarbon group and an aromatic hydrocarbon group include phenoxyethyl group and benzyl group. Among these, from the viewpoint of further improving the adhesive strength of the adhesive layer (X1), the component (a1) preferably contains a monomer (a1-1) having an energy ray-polymerizable functional group and a linear or branched aliphatic hydrocarbon group (hereinafter also referred to as “component (a1-1)”), a monomer (a1-2) having an energy ray-polymerizable functional group and an alicyclic hydrocarbon group (hereinafter also referred to as “component (a1-2)”), and the like.

[0052] When the component (a1) contains the component (a1-1), its content is preferably 20 to 80% by mass, more preferably 40 to 70% by mass, and still more preferably 50 to 60% by mass with respect to the total of the component (a1) (100% by mass). When the (a1) component contains the (a1-2) component, its content is preferably 5 to 60% by mass, more preferably 10 to 40% by mass, still more preferably 20 to 30% by mass, based on the total (100% by mass) of the (a1) component.

[0053] Examples of the monomer having an energy ray-polymerizable functional group and a functional group other than the energy ray-polymerizable functional group include monomers having a functional group other than the energy ray-polymerizable functional group, such as a hydroxy group, a carboxy group, a thiol group, a primary or secondary amino group, etc. Among these, from the viewpoint of further improving the formability of the pressure-sensitive adhesive layer (X1), the (a1) component preferably contains a monomer (a1-3) having an energy ray-polymerizable functional group and a hydroxy group (hereinafter also referred to as the "(a1-3) component"). When the (a1) component contains the (a1-3) component, its content is preferably 1 to 60% by mass, more preferably 5 to 30% by mass, still more preferably 10 to 20% by mass, based on the total (100% by mass) of the (a1) component.

[0054] The number of the energy ray-polymerizable functional groups possessed by the (a1) component may be 1 or 2 or more. Also, from the viewpoint of further improving the self-peeling property of the pressure-sensitive adhesive layer (X1), the (a1) component preferably contains a monomer (a1-4) having 3 or more energy ray-polymerizable functional groups (hereinafter also referred to as the "(a1-4) component"). When the (a1) component contains the (a1-4) component, its content is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, still more preferably 3 to 10% by mass, based on the total (100% by mass) of the (a1) component.

[0055] As the monomer having one energy ray-polymerizable functional group, a monomer having one vinyl group-containing group (hereinafter also referred to as a "polymerizable vinyl monomer") is preferable. As the monomer having two or more energy ray-polymerizable functional groups, a monomer having two or more (meth)acryloyl groups (hereinafter also referred to as "polyfunctional (meth)acrylate monomer") is preferable. By containing the above compound in the component (a1), the cohesive force of the pressure-sensitive adhesive obtained by polymerizing these can be improved, and a pressure-sensitive adhesive layer (X1) with less adherend contamination after peeling can be formed.

[0056] 《Polymerizable Vinyl Monomer》 The polymerizable vinyl monomer is not particularly limited as long as it has a vinyl group-containing group, and conventionally known ones can be appropriately used. The polymerizable vinyl monomer may be used alone or in combination of two or more.

[0057] Examples of the polymerizable vinyl monomer include compounds corresponding to the above component (a1-1) such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate; compounds corresponding to the above component (a1-2) such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate; (meth)acrylates having no functional group other than the vinyl group-containing group in the molecule such as phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, polyoxyalkylene-modified (meth)acrylate. Among these, 2-ethylhexyl acrylate and isobornyl acrylate are preferable.

[0058] The polymerizable vinyl monomer may further have a functional group other than the vinyl group-containing group in the molecule. Examples of the functional group include a hydroxy group, a carboxy group, a thiol group, a primary or secondary amino group, etc. Among these, the polymerizable vinyl monomer having a hydroxy group corresponding to the above component (a1-3) is preferable. Examples of the polymerizable vinyl monomer having a hydroxy 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; hydroxy group-containing acrylamides such as N-methylolacrylamide and N-methylolmethacrylamide. Examples of the polymerizable vinyl monomer having a carboxy group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Among these, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferred.

[0059] Examples of other polymerizable vinyl monomers include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene-based monomers such as styrene and α-methylstyrene; diene-based monomers such as butadiene, isoprene, and chloroprene; nitrile-based monomers such as acrylonitrile and methacrylonitrile; amide-based monomers such as acrylamide, methacrylamide, N-methylacrylamide, N-methylmethacrylamide, N,N-dimethyl (meth) acrylamide, N,N-diethyl (meth) acrylamide, and N-vinylpyrrolidone; tertiary amino group-containing monomers such as N,N-diethylaminoethyl (meth) acrylate and N-(meth) acryloylmorpholine.

[0060] 《Polyfunctional (meth) acrylate monomer》 The polyfunctional (meth) acrylate monomer is not particularly limited as long as it has two or more (meth) acryloyl groups in one molecule, and conventionally known ones can be appropriately used. The polyfunctional (meth) acrylate monomer may be used alone or in combination of two or more.

[0061] Examples of the polyfunctional (meth)acrylate monomer include bifunctional (meth)acrylate monomers such as 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, neopentyl glycol adipate di(meth)acrylate, neopentyl glycol hydroxypivalate di(meth)acrylate, dicyclopentanyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified diphosphate di(meth)acrylate, di(acryloxyethyl) isocyanurate, allylated cyclohexyl di(meth)acrylate, and ethylene oxide-modified diacrylate of isocyanuric acid; polyfunctional (meth)acrylate monomers corresponding to the above (a1-4) components such as trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl) isocyanurate, bis(acryloxyethyl) hydroxyethyl isocyanurate, ethylene oxide-modified triacrylate of isocyanuric acid, ε-caprolactone-modified tris(acryloxyethyl) isocyanurate, diglycerin tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.

[0062] 《Content of Component (a1)》 In the polymerizable composition (x-1A), the total content of the polymerizable vinyl monomer is preferably 10 to 80% by mass, more preferably 30 to 75% by mass, and still more preferably 50 to 70% by mass with respect to the total amount (100% by mass) of the active ingredients of the polymerizable composition (x-1A). The total content of the polyfunctional (meth)acrylate monomer in the coincidence composition (x-1A) is preferably 0.5 to 15% by mass, more preferably 1 to 10% by mass, and still more preferably 2 to 5% by mass with respect to the total amount (100% by mass) of the active ingredients of the polymerizable composition (x-1A). The total content of the component (a1) in the polymerizable composition (x-1A) is preferably 15 to 90% by mass, more preferably 35 to 80% by mass, and still more preferably 55 to 75% by mass with respect to the total amount (100% by mass) of the active ingredients of the polymerizable composition (x-1A).

[0063] (Prepolymer (a2) having an energy ray-polymerizable functional group) Examples of the prepolymer (a2) having an energy ray-polymerizable functional group include a prepolymer having one energy ray-polymerizable functional group and a prepolymer having two or more energy ray-polymerizable functional groups. Among these, from the viewpoint of forming a pressure-sensitive adhesive layer having excellent self-peeling property and little contamination of the adherend after peeling, the component (a2) preferably contains a prepolymer having two or more energy ray-polymerizable functional groups, more preferably contains a prepolymer having two energy ray-polymerizable functional groups, and still more preferably contains a prepolymer having two energy ray-polymerizable functional groups and having the energy ray-polymerizable functional groups at both ends.

[0064] As the component (a2), it is preferable to contain a prepolymer having two or more (meth)acryloyl groups as an energy ray-polymerizable functional group (hereinafter also referred to as "polyfunctional (meth)acrylate prepolymer"). By the component (a2) containing the above compound, the cohesive force of the pressure-sensitive adhesive obtained by polymerizing these can be improved, and a pressure-sensitive adhesive layer (X1) having excellent self-peeling property and little contamination of the adherend after peeling can be formed.

[0065] 《Polyfunctional (meth)acrylate prepolymer》 The polyfunctional (meth)acrylate prepolymer is not particularly limited as long as it is a prepolymer having two or more (meth)acryloyl groups in one molecule, and conventionally known ones can be appropriately used. The polyfunctional (meth)acrylate prepolymer may be used alone or in combination of two or more thereof.

[0066] Examples of the polyfunctional (meth)acrylate prepolymer include urethane acrylate prepolymers, polyester acrylate prepolymers, epoxy acrylate prepolymers, polyether acrylate prepolymers, polybutadiene acrylate prepolymers, silicone acrylate prepolymers, polyacrylic acrylate prepolymers, and the like.

[0067] The urethane acrylate prepolymer can be obtained, for example, by esterifying a polyurethane prepolymer obtained by the reaction of a compound such as a polyalkylene polyol, a polyether polyol, a polyester polyol, a hydrogenated isoprene having a hydroxy group at the terminal, or a hydrogenated butadiene having a hydroxy group at the terminal with a polyisocyanate with (meth)acrylic acid or a (meth)acrylic acid derivative.

[0068] Examples of the polyalkylene polyol used in the production of the urethane acrylate prepolymer include polypropylene glycol, polyethylene glycol, polybutylene glycol, polyhexylene glycol, etc. Among these, polypropylene glycol is preferred. When the number of functional groups of the obtained urethane acrylate prepolymer is 3 or more, for example, glycerin, trimethylolpropane, triethanolamine, pentaerythritol, ethylenediamine, diethylenetriamine, sorbitol, sucrose, etc. may be appropriately combined.

[0069] Examples of the polyisocyanate used in the production of the urethane acrylate prepolymer include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylene diisocyanate; aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, and diphenyl diisocyanate; alicyclic diisocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate. Among these, aliphatic diisocyanates are preferred, and hexamethylene diisocyanate is more preferred. Note that the polyisocyanate is not limited to bifunctional ones, and those with trifunctional or more can also be used.

[0070] Examples of the (meth)acrylic acid derivative used in the production of the urethane acrylate prepolymer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate; 2-isocyanate ethyl acrylate, 2-isocyanate ethyl methacrylate, 1,1-bis(acryloxymethyl)ethyl isocyanate, etc. Among these, 2-isocyanate ethyl acrylate is preferred.

[0071] Another production method of the urethane acrylate prepolymer includes a method of reacting the hydroxy group of compounds such as polyalkylene polyol, polyether polyol, polyester polyol, hydrogenated isoprene having a hydroxy group at the terminal, and hydrogenated butadiene having a hydroxy group at the terminal with the -N=C=O moiety of isocyanate alkyl (meth)acrylate. In this case, examples of the isocyanate alkyl (meth)acrylate include the above-mentioned 2-isocyanate ethyl acrylate, 2-isocyanate ethyl methacrylate, 1,1-bis(acryloxymethyl)ethyl isocyanate, etc. which can be used.

[0072] A polyester acrylate prepolymer can be obtained, for example, by esterifying the hydroxy groups of a polyester prepolymer having hydroxy groups at both ends, which is obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol, with (meth)acrylic acid. It can also be obtained by esterifying the terminal hydroxy groups of a prepolymer obtained by adding an alkylene oxide to a polyvalent carboxylic acid with (meth)acrylic acid.

[0073] An epoxy acrylate prepolymer can be obtained, for example, by reacting (meth)acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin, novolac type epoxy resin, etc. to carry out esterification. Also, a carboxy-modified epoxy acrylate prepolymer obtained by partially modifying an epoxy acrylate prepolymer with a dibasic carboxylic acid anhydride can also be used.

[0074] A polyether acrylate prepolymer can be obtained, for example, by esterifying the hydroxy groups of a polyether polyol with (meth)acrylic acid.

[0075] A polyacrylic acrylate prepolymer may have an acryloyl group in the side chain, or may have an acryloyl group at both ends or one end. A polyacrylic acrylate prepolymer having an acryloyl group in the side chain can be obtained, for example, by adding glycidyl methacrylate to the carboxy groups of polyacrylic acid. Also, a polyacrylic acrylate prepolymer having acryloyl groups at both ends can be obtained, for example, by introducing acryloyl groups at both ends by utilizing the polymerization growth terminal structure of a polyacrylate prepolymer synthesized by the ATRP (Atom Transfer Radical Polymerization) method.

[0076] The mass average molecular weight (Mw) of the component (a2) is preferably from 10,000 to 350,000, more preferably from 15,000 to 200,000, and still more preferably from 20,000 to 50,000.

[0077] Content of component (a2) The total content of the polyfunctional (meth)acrylate prepolymer in the polymerizable composition (x-1A) is preferably 10 to 60% by mass, more preferably 15 to 55% by mass, still more preferably 20 to 30% by mass, based on the total amount (100% by mass) of the active ingredients of the polymerizable composition (x-1A). The total content of component (a2) in the polymerizable composition (x-1A) is preferably 10 to 60% by mass, more preferably 15 to 55% by mass, still more preferably 20 to 30% by mass, based on the total amount (100% by mass) of the active ingredients of the polymerizable composition (x-1A).

[0078] The content ratio [(a2) / (a1)] of component (a2) and component (a1) in the polymerizable composition (x-1A) is preferably 10 / 90 to 70 / 30, more preferably 20 / 80 to 50 / 50, still more preferably 25 / 75 to 40 / 60, on a mass basis.

[0079] Among the above energy ray-polymerizable components, the polymerizable composition (x-1A) preferably contains a polymerizable vinyl monomer, a polyfunctional (meth)acrylate monomer, and a polyfunctional (meth)acrylate prepolymer. The total content of the polymerizable vinyl monomer, the polyfunctional (meth)acrylate monomer, and the polyfunctional (meth)acrylate prepolymer in the energy ray-polymerizable components contained in the polymerizable composition (x-1A) is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, even more preferably 99% by mass or more, and may be 100% by mass, based on the total amount (100% by mass) of the energy ray-polymerizable components.

[0080] The total content of the energy ray-polymerizable components is preferably 70 to 98% by mass, more preferably 75 to 97% by mass, still more preferably 80 to 96% by mass, even more preferably 82 to 95% by mass, based on the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition (x-1A) or the total mass (100% by mass) of the pressure-sensitive adhesive layer (X1). The total content of the above energy ray-polymerizable component can be read as the content of the polymer obtained by subjecting the energy ray-polymerizable component contained in the pressure-sensitive adhesive layer (X1) to energy ray polymerization.

[0081] (Thermally expandable particles) Regarding the preferred embodiments of the thermally expandable particles contained in the polymerizable composition (x-1A), they are the same as the preferred embodiments of the thermally expandable particles described as the components contained in the above pressure-sensitive adhesive layer (X1). The content of the thermally expandable particles with respect to the total mass (100% by mass) of the above pressure-sensitive adhesive layer (X1) can be read as the content of the thermally expandable particles with respect to the total amount (100% by mass) of the active ingredients of the polymerizable composition (x-1A).

[0082] (Photoinitiator) The polymerizable composition (x-1A) preferably contains a photoinitiator from the viewpoint of more efficiently promoting the polymerization of the energy ray-polymerizable component. Examples of the photoinitiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin - n - butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2 - dimethoxy - 2 - phenylacetophenone, 2,2 - diethoxy - 2 - phenylacetophenone, 2 - hydroxy - 2 - methyl - 1 - phenylpropan - 1 - one, 1 - hydroxycyclohexyl phenyl ketone, 2 - methyl - 1 - [4 - (methylthio)phenyl] - 2 - morpholino - propan - 1 - one, 4 - (2 - hydroxyethoxy)phenyl - 2 - (hydroxy - 2 - propyl) ketone, benzophenone, p - phenylbenzophenone, 4,4’ - diethylaminobenzophenone, dichlorobenzophenone, 2 - methylanthraquinone, 2 - ethylanthraquinone, 2 - tert - butylanthraquinone, 2 - aminoanthraquinone, 2 - methylthioxanthone, 2 - ethylthioxanthone, 2 - chlorothioxanthone, 2,4 - dimethylthioxanthone, 2,4 - diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p - dimethylaminobenzoic acid ester, oligo[2 - hydroxy - 2 - methyl - 1[4 - (1 - methylvinyl)phenyl]propanone], 2,4,6 - trimethylbenzoyl - diphenyl - phosphine oxide, and the like. The photoinitiator may be used alone or in combination of two or more.

[0083] When the polymerizable composition (x - 1A) contains a photoinitiator, its content is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, and still more preferably 0.3 to 1 part by mass with respect to 100 parts by mass of the energy ray - polymerizable component. If the content of the photoinitiator is 0.1 part by mass or more, the polymerization of the energy ray - polymerizable component can proceed more efficiently. On the other hand, if the content is 10 parts by mass or less, it becomes possible to eliminate or reduce the unreacted remaining photoinitiator, and it becomes easier to adjust the obtained pressure - sensitive adhesive layer (X1) to desired physical properties.

[0084] (Solvent) Incidentally, the polymerizable composition (x-1A) may contain a solvent such as a diluent within a range not contrary to the object of the present invention, but it is preferably solvent-free. That is, the polymerizable composition (x-1A) is preferably a solvent-free polymerizable composition. Since the polymerizable composition (x-1A) is a solvent-free polymerizable composition, when forming the pressure-sensitive adhesive layer (X1), heating and drying of the solvent can be omitted, so that expansion of the thermally expandable particles during heating and drying can be suppressed. Further, when a solvent is used, the thermally expandable particles may be unevenly distributed on one surface side due to volume reduction during drying, and the adhesion to the base material (Y) or the adhesive strength of the adhesive surface may be lowered. On the other hand, in the case of a solvent-free polymerizable composition, polymerization proceeds while the thermally expandable particles are uniformly dispersed in the energy ray-polymerizable component, and the pressure-sensitive adhesive layer (X1) is formed, so that the above problems are less likely to occur. When the polymerizable composition (x-1A) contains a solvent, the smaller the content, the more preferable. With respect to the total amount (100% by mass) of the active ingredients of the polymerizable composition (x-1A), it is preferably 10% by mass or less, more preferably 1% by mass or less, still more preferably 0.1% by mass or less, and even more preferably 0.01% by mass or less.

[0085] The polymerizable composition (x-1A) may contain other components other than the above components. Examples of other components include an adhesion promoter and an additive for pressure-sensitive adhesives described later.

[0086] (Method for producing the polymerizable composition (x-1A)) The polymerizable composition (x-1A) can be produced by mixing an energy ray-polymerizable component, thermally expandable particles, and other components that are contained as necessary. Since the resulting polymerizable composition (x-1A) polymerizes the energy ray-polymerizable component into a high molecular weight by subsequent energy ray polymerization, when forming a layer, the viscosity can be adjusted to an appropriate level by the low molecular weight energy ray-polymerizable component. Therefore, the polymerizable composition (x-1A) can be used as it is as a coating solution for forming the pressure-sensitive adhesive layer (X1) without adding a solvent such as a diluent. In the pressure-sensitive adhesive layer (X1) formed by irradiating the polymerizable composition (x-1A) with energy rays, there are various polymers formed by polymerization of energy ray-polymerizable components and thermally expandable particles dispersed in the polymers. However, there are circumstances where it is impossible or not practically feasible to directly identify these by structure and physical properties.

[0087] -Method using the pressure-sensitive adhesive composition (x-1B)- The method using the pressure-sensitive adhesive composition (x-1B) is a method of forming the pressure-sensitive adhesive layer (X1) by applying the pressure-sensitive adhesive composition (x-1B) containing a pressure-sensitive adhesive resin and thermally expandable particles. According to this method, the pressure-sensitive adhesive resin contained in the pressure-sensitive adhesive layer (X1) is the pressure-sensitive adhesive resin itself contained in the pressure-sensitive adhesive composition (x-1B).

[0088] The pressure-sensitive adhesive composition (x-1B) contains a pressure-sensitive adhesive resin and thermally expandable particles. Hereinafter, each component contained in the pressure-sensitive adhesive composition (x-1B) will be described.

[0089] Regarding the preferred embodiments of the thermally expandable particles contained in the pressure-sensitive adhesive composition (x-1B), they are the same as the preferred embodiments of the thermally expandable particles described as the components contained in the above-described pressure-sensitive adhesive layer (X1). The content of the thermally expandable particles with respect to the total mass (100% by mass) of the above-described pressure-sensitive adhesive layer (X1) can be read as the content of the thermally expandable particles with respect to the total amount (100% by mass) of the active ingredients of the pressure-sensitive adhesive composition (x-1B).

[0090] As the pressure-sensitive adhesive resin contained in the pressure-sensitive adhesive composition (x-1B), a polymer having adhesiveness by itself and a mass average molecular weight (Mw) of 10,000 or more may be used. Regarding the mass average molecular weight (Mw) of the pressure-sensitive adhesive resin, from the viewpoint of improving the adhesive strength, it is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and still more preferably 30,000 to 1,000,000. Specific adhesive resins include, for example, acrylic resins, urethane resins, rubber-based resins such as polyisobutylene resins, polyester resins, olefin resins, silicone resins, polyvinyl ether resins, and the like. Among these, from the viewpoint of exhibiting excellent adhesive strength and from the viewpoint of easily forming irregularities on the surface of the formed adhesive layer due to the expansion of the thermally expandable particles by heat treatment, it is preferable that the adhesive resin contains an acrylic resin. These adhesive resins may be used alone or in combination of two or more. Further, when these adhesive resins are copolymers having two or more structural units, the form of the copolymer is not particularly limited, and any of a block copolymer, a random copolymer, and a graft copolymer may be used.

[0091] The content of the adhesive resin is preferably 30 to 99.99% by mass, more preferably 40 to 99.95% by mass, still more preferably 50 to 99.90% by mass, even more preferably 55 to 99.80% by mass, and still more preferably 60 to 99.50% by mass, based on the total amount of the active ingredients (100% by mass) of the adhesive composition (x-1B) or the total mass (100% by mass) of the adhesive layer (X1).

[0092] The adhesive composition (x-1B) may contain other components other than the above components. Examples of other components include solvents, adhesion promoters described later, additives for adhesives, and the like.

[0093] The adhesive composition (x-1B) can be produced by mixing the adhesive resin and other components used as necessary.

[0094] 〔Other Components〕 The adhesive layer (X1) may contain other components other than the adhesive resin and the thermally expandable particles. Examples of the above other components include adhesion promoters and additives for adhesives used in general adhesives other than the above components.

[0095] (Adhesion Promoter) The tackifier is a component that is used as needed for the purpose of further improving the adhesive strength. In this specification, the "tackifier" refers to those with a mass average molecular weight (Mw) of less than 10,000, and is distinguished from the pressure-sensitive adhesive resin. The mass average molecular weight (Mw) of the tackifier is less than 10,000, preferably 400 to 9,000, more preferably 500 to 8,000, and still more preferably 800 to 5,000.

[0096] Examples of the tackifier include rosin-based resins, terpene-based resins, styrene-based resins, C5 fractions such as pentene, isoprene, piperine, and 1,3-pentadiene produced by thermal decomposition of petroleum naphtha, C5-based petroleum resins obtained by copolymerizing these, C9 fractions such as indene and vinyltoluene produced by thermal decomposition of petroleum naphtha, C9-based petroleum resins obtained by copolymerizing these, and hydrogenated resins obtained by hydrogenating these.

[0097] The softening point of the tackifier is preferably 60 to 170 °C, more preferably 65 to 160 °C, and still more preferably 70 to 150 °C. In this specification, the "softening point" of the tackifier means the value measured in accordance with JIS K 2531. The tackifier may be used alone, or two or more kinds with different softening points, structures, etc. may be used in combination. When using two or more kinds of tackifiers, it is preferable that the weighted average of the softening points of these plural tackifiers belongs to the above range.

[0098] When the pressure-sensitive adhesive layer (X1) contains a tackifier, its content is preferably 0.01 to 65% by mass, more preferably 0.1 to 50% by mass, still more preferably 1 to 40% by mass, and even more preferably 2 to 30% by mass with respect to the total mass (100% by mass) of the pressure-sensitive adhesive layer (X1).

[0099] (Additives for pressure-sensitive adhesives) Examples of additives for adhesives include silane coupling agents, antioxidants, softeners (plasticizers), rust preventives, pigments, dyes, retarders, reaction accelerators (catalysts), ultraviolet absorbers, and the like. These additives for adhesives may be used alone or in combination of two or more thereof.

[0100] When the adhesive layer (X1) contains an additive for an adhesive, the content of each additive for an adhesive is preferably 0.0001 to 20 parts by mass, more preferably 0.001 to 10 parts by mass, based on the total mass (100% by mass) of the adhesive layer (X1).

[0101] 〔Physical properties, etc. of the adhesive layer (X1)〕 (Adhesive force at 23°C before thermal expansion of the adhesive layer (X1)) The adhesive force of the adhesive layer (X1) at 23°C before thermal expansion is preferably 0.1 to 12.0 N / 25 mm, more preferably 0.5 to 9.0 N / 25 mm, still more preferably 1.0 to 8.0 N / 25 mm, and even more preferably 1.2 to 7.5 N / 25 mm. If the adhesive force of the adhesive layer (X1) at 23°C before thermal expansion is 0.1 N / 25 mm or more, unintentional peeling from the adherend and displacement of the adherend during temporary fixing can be more effectively suppressed. On the other hand, if the adhesive force is 12.0 N / 25 mm or less, the peelability during heat peeling can be further improved. In this specification, the adhesive force of the adhesive layer means the adhesive force to the mirror surface of the silicon mirror wafer. Also, in this specification, the adhesive force of the adhesive layer (X1) at 23°C before thermal expansion specifically means the value measured by the method described in the examples.

[0102] (Adhesive force at 23°C after thermal expansion of the adhesive layer (X1)) The adhesive force of the adhesive layer (X1) at 23°C after thermal expansion is preferably 1.5 N / 25 mm or less, more preferably 0.05 N / 25 mm or less, still more preferably 0.01 N / 25 mm or less, and even more preferably 0 N / 25 mm. Note that an adhesive force of 0 N / 25 mm means an adhesive force below the measurement limit in the method for measuring the adhesive force at 23°C after thermal expansion described below, and includes cases where the adhesive force is too small and the adhesive sheet peels off unintentionally when fixing the adhesive sheet for measurement. In this specification, the adhesive force of the adhesive layer (X1) at 23°C after thermal expansion specifically means the value measured by the method described in the examples.

[0103] (Shear storage modulus G'(23) of the adhesive layer (X1) at 23°C) The shear storage modulus G'(23) of the adhesive layer (X1) at 23°C is preferably 1.0×10 4 ~5.0×10 7 Pa, more preferably 5.0×10 4 ~1.0×10 7 Pa, still more preferably 1.0×10 5 ~5.0×10 6 Pa. If the shear storage modulus G'(23) of the adhesive layer (X1) is 1.0×10 4 Pa or more, displacement of the adherend during temporary fixing and excessive sinking of the adherend into the adhesive layer (X1) can be suppressed. On the other hand, if the shear storage modulus G'(23) is 5.0×10 7 Pa or less, unevenness is likely to be formed on the surface of the adhesive layer (X1) due to the expansion of the thermally expandable particles, and the peelability during heat peeling tends to improve. Note that in this specification, the shear storage modulus G'(23) of the adhesive layer (X1) at 23°C means the value measured by the method described in the examples.

[0104] The adhesive layer (X1) is a layer containing thermally expandable particles, and the shear storage modulus G' of the adhesive layer (X1) can be affected by the thermally expandable particles. From the perspective of measuring the shear storage modulus G' excluding the influence of the thermally expandable particles, an adhesive layer having the same composition as the adhesive layer (X1) except for not containing thermally expandable particles (hereinafter, also referred to as "non-expandable adhesive layer (X1')") may be prepared, and the shear storage modulus G' of the adhesive layer may be measured.

[0105] (Shear storage modulus G'(23) of the non-expandable adhesive layer (X1') at 23°C) The shear storage modulus G'(23) of the non-expandable adhesive layer (X1') at 23°C is preferably 1.0×10 4 ~5.0×10 7 Pa, more preferably 5.0×10 4 ~1.0×10 7 Pa, still more preferably 1.0×10 5 ~5.0×10 6 Pa. If the shear storage modulus G'(23) of the non-expandable adhesive layer (X1') is 1.0×10 4 Pa or more, displacement of the adherend during temporary fixing, excessive sinking of the adherend into the adhesive layer (X1), etc. can be suppressed. On the other hand, if the shear storage modulus G'(23) is 5.0×10 7 Pa or less, unevenness is likely to be formed on the surface of the adhesive layer (X1) due to the expansion of the thermally expandable particles, and the peelability at the time of heat peeling tends to be improved.

[0106] (Shear storage modulus G'(t) of the non-expandable adhesive layer (X1') at the expansion start temperature (t)) The shear storage modulus G'(t) of the non-expandable adhesive layer (X1') at the expansion start temperature (t) of the thermally expandable particles is preferably 5.0×10 3 ~1.0×10 7 Pa, more preferably 1.0×10 4 ~5.0×10 6 Pa, still more preferably 5.0×10 4 ~1.0×10 6 Pa. If the shear storage modulus G’(t) of the non-expandable adhesive layer (X1’) is 5.0×10 3 Pa or more, displacement of the adherend during temporary fixing and excessive sinking of the adherend into the adhesive layer (X1) can be suppressed, and curling of the adhesive sheet during heat peeling can be suppressed, tending to improve the handleability. On the other hand, if the shear storage modulus G’(t) is 1.0×10 7 Pa or less, unevenness is likely to be formed on the surface of the adhesive layer (X1) due to the expansion of the thermally expandable particles, and the peelability during heat peeling tends to improve. In the present specification, the shear storage modulus G’ of the non-expandable adhesive layer (X1’) at a predetermined temperature means the value measured by the method described in the examples.

[0107] (Thickness of the adhesive layer (X1) at 23°C) The thickness of the adhesive layer (X1) at 23°C is preferably 5 to 150 μm, more preferably 10 to 100 μm, and still more preferably 20 to 80 μm. If the thickness of the adhesive layer (X1) at 23°C is 5 μm or more, sufficient adhesive force is likely to be obtained, and unintended peeling from the adherend and displacement of the adherend during temporary fixing can be suppressed. On the other hand, if the thickness of the adhesive layer (X1) at 23°C is 150 μm or less, the peelability during heat peeling is improved, and curling of the adhesive sheet during heat peeling can be suppressed, tending to improve the handleability. In the present specification, the thickness of the adhesive layer means the value measured by the method described in the examples. Also, the thickness of the adhesive layer (X1) is the value before the expansion of the thermally expandable particles.

[0108] <Adhesive layer (X2)> The adhesive layer (X2) is an adhesive layer that cures by irradiation with energy rays and has a reduced adhesive force. The pressure-sensitive adhesive sheet used in one aspect of the present invention has a pressure-sensitive adhesive layer for attaching an object to be processed. By making the pressure-sensitive adhesive layer (X2) that cures upon irradiation with energy rays and has a reduced adhesive force, when peeling the object to be processed from the pressure-sensitive adhesive sheet, the surface of the object to be processed is not contaminated by the thermally expandable particles and the expanded pressure-sensitive adhesive layer. Further, by making the action mechanisms for reducing the adhesive force of the pressure-sensitive adhesive layer different between the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2), when performing a process for reducing the adhesive force of either one of the pressure-sensitive adhesive layers, it is possible to suppress unintentionally reducing the adhesive force of the other pressure-sensitive adhesive layer as well.

[0109] The pressure-sensitive adhesive layer (X2) is preferably a non-thermally expandable layer, and the volume change rate (%) of the pressure-sensitive adhesive layer (X2) calculated from the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, still more preferably less than 0.1%, and even more preferably less than 0.01%. The pressure-sensitive adhesive layer (X2) preferably does not contain thermally expandable particles, but may contain thermally expandable particles within a range not contrary to the object of the present invention. When the pressure-sensitive adhesive layer (X2) contains thermally expandable particles, the lower the content, the more preferable it is. With respect to the total mass (100% by mass) of the pressure-sensitive adhesive layer (X2), it is preferably less than 3% by mass, more preferably less than 1% by mass, still more preferably less than 0.1% by mass, even more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass.

[0110] The pressure-sensitive adhesive layer (X2) is preferably formed from an energy ray-curable pressure-sensitive adhesive composition (x-2) (hereinafter, also simply referred to as "pressure-sensitive adhesive composition (x-2)"). By forming from the pressure-sensitive adhesive composition (x-2), the pressure-sensitive adhesive layer (X2) can be made into a pressure-sensitive adhesive layer that cures upon irradiation with energy rays and has a reduced adhesive force. Hereinafter, each component contained in the pressure-sensitive adhesive composition (x-2) will be described.

[0111] Examples of the energy ray curable pressure-sensitive adhesive composition (x-2) include a pressure-sensitive adhesive composition (x-2A) containing an energy ray curable low molecular compound together with a non-energy ray curable pressure-sensitive adhesive resin (I) (hereinafter also referred to as "pressure-sensitive adhesive resin (I)"), or a pressure-sensitive adhesive composition (x-2B) containing an energy ray curable pressure-sensitive adhesive resin (II) (hereinafter also referred to as "pressure-sensitive adhesive resin (II)") in which an unsaturated group is introduced into the side chain of a non-energy ray curable pressure-sensitive adhesive resin, etc.

[0112] [Non-energy ray curable pressure-sensitive adhesive resin (I)] The mass average molecular weight (Mw) of the non-energy ray curable pressure-sensitive adhesive resin (I) is preferably 250,000 to 1,500,000, more preferably 350,000 to 1,300,000, still more preferably 450,000 to 1,100,000, and even more preferably 650,000 to 1,050,000.

[0113] Examples of the non-energy ray curable pressure-sensitive adhesive resin (I) include acrylic resins, rubber resins, silicone resins, etc. Among these, acrylic resins are preferred. Hereinafter, acrylic resins will be described in detail.

[0114] (Acrylic resin) The acrylic resin is preferably a resin containing a structural unit (p1) derived from an alkyl (meth)acrylate monomer having an alkyl group with 4 or more carbon atoms (hereinafter also referred to as "monomer (p1)"). The acrylic resin may be a homopolymer consisting only of the structural unit (p1) derived from the above monomer (p1), but is preferably a copolymer containing the structural unit (p1) and further a structural unit (p2) derived from an alkyl (meth)acrylate monomer having an alkyl group with 1 to 3 carbon atoms (hereinafter also referred to as "monomer (p2)") and / or a structural unit (p3) derived from a functional group-containing monomer (p3) (hereinafter also referred to as "monomer (p3)").

[0115] The number of carbon atoms of the alkyl group of the monomer (p1) is preferably 4 to 20, more preferably 4 to 12, and still more preferably 4 to 6, from the viewpoint of improving the adhesive strength of the adhesive layer (X2). Further, the alkyl group of the monomer (p1) may be either linear or branched.

[0116] Examples of the monomer (p1) include butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, and the like. These monomers (p1) may be used alone or in combination of two or more. Among these, butyl (meth)acrylate is preferable from the viewpoint of improving the adhesive strength of the adhesive layer (X2).

[0117] When the acrylic resin is a copolymer, the content of the structural unit (p1) relative to all the structural units of the acrylic resin is preferably 40 to 98% by mass, more preferably 45 to 95% by mass, and still more preferably 50 to 90% by mass.

[0118] Examples of the monomer (p2) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, and the like. These monomers (p2) may be used alone or in combination of two or more. Among these, methyl (meth)acrylate is preferable.

[0119] When the acrylic resin is a copolymer, the content of the structural unit (p2) relative to all the structural units of the acrylic resin is preferably 1 to 30% by mass, more preferably 3 to 26% by mass, and still more preferably 6 to 22% by mass.

[0120] The monomer (p3) means a monomer having a functional group that can react with a crosslinking agent described later and serve as a crosslinking starting point or a functional group having a crosslinking promoting effect. Examples of the functional groups of the monomer (p3) include a hydroxyl group, a carboxy group, an amino group, an epoxy group, etc. Among these, from the viewpoint of reactivity with a crosslinking agent, a carboxy group or a hydroxyl group is preferable.

[0121] Examples of the monomer (p3) include a hydroxyl group-containing monomer, a carboxy group-containing monomer, an amino group-containing monomer, an epoxy group-containing monomer, etc. These monomers (p3) may be used alone or in combination of two or more. Among these, a hydroxyl group-containing monomer and a carboxy group-containing monomer are preferable, and a hydroxyl group-containing monomer is more preferable.

[0122] Examples of the hydroxyl group-containing monomer 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, 4-hydroxybutyl (meth) acrylate; unsaturated alcohols such as vinyl alcohol and allyl alcohol.

[0123] Examples of the carboxy group-containing monomer include ethylenically unsaturated monocarboxylic acids such as (meth) acrylic acid and crotonic acid; ethylenically unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, maleic acid, citraconic acid and their anhydrides, and 2-carboxyethyl methacrylate.

[0124] When the acrylic resin is a copolymer, the content of the structural unit (p3) relative to all the structural units of the acrylic resin is preferably 1 to 35% by mass, more preferably 3 to 32% by mass, still more preferably 6 to 30% by mass.

[0125] Further, the acrylic resin may contain a structural unit derived from a monomer copolymerizable with an acrylic monomer other than the above structural units (p1) to (p3). Examples of the monomer include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, acrylamide, and the like.

[0126] [Energy ray curable pressure sensitive adhesive resin (II)] The pressure sensitive adhesive resin (II) is an energy ray curable pressure sensitive adhesive resin obtained by introducing an unsaturated group into the side chain of the above-described non-energy ray curable pressure sensitive adhesive resin (I). The mass average molecular weight (Mw) of the energy ray curable pressure sensitive adhesive resin (II) having an unsaturated group introduced into the side chain is preferably 300,000 to 1,600,000, more preferably 400,000 to 1,400,000, still more preferably 500,000 to 1,200,000, and even more preferably 700,000 to 1,100,000. As the main chain of the pressure sensitive adhesive resin (II), the above-described pressure sensitive adhesive resin (I) can be used, but an acrylic resin is preferred, and an acrylic copolymer having structural units (p1), (p2), and (p3) is more preferred. Examples of the unsaturated group in the side chain of the pressure sensitive adhesive resin (II) include (meth)acryloyl group, vinyl group, allyl group, etc., and (meth)acryloyl group is preferred.

[0127] Examples of the synthesis method of the pressure sensitive adhesive resin (II) include a method in which a functional group-containing monomer is copolymerized with the pressure sensitive adhesive resin (I) to provide a functional group, a compound having both a substituent and an unsaturated group capable of bonding to the functional group is added, and the functional group of the copolymer and the substituent are bonded to each other. Examples of the functional group-containing monomer copolymerized with the pressure sensitive adhesive resin (I) include the compounds listed as the above monomer (p3). Examples of the substituent that binds to the functional group include an isocyanate group, a glycidyl group, etc. Therefore, examples of the compound having both a substituent and an unsaturated group capable of bonding to the functional group include (meth)acryloyloxyethyl isocyanate, (meth)acryloyl isocyanate, glycidyl (meth)acrylate, and the like.

[0128] [Crosslinking agent] The pressure-sensitive adhesive compositions (x-2A) and (x-2B) preferably further contain a crosslinking agent. The main purpose of adding the crosslinking agent is to react with functional groups on the side chains of the non-energy-ray-curable pressure-sensitive adhesive resin (I) or the energy-ray-curable pressure-sensitive adhesive resin (II), such as functional groups derived from the monomer (p3) of the above acrylic resin, to crosslink the pressure-sensitive adhesive resins with each other.

[0129] Examples of the crosslinking agent include isocyanate-based crosslinking agents such as tolylene diisocyanate, hexamethylene diisocyanate, and their adducts; epoxy-based crosslinking agents such as ethylene glycol glycidyl ether; aziridine-based crosslinking agents such as hexa[1-(2-methyl)-aziridinyl]phosphatriazine; chelate-based crosslinking agents such as aluminum chelate; and the like. These crosslinking agents may be used alone or in combination of two or more. Among these, isocyanate-based crosslinking agents are preferred from the viewpoints of enhancing cohesion and improving adhesive strength and ease of availability.

[0130] The blending amount of the crosslinking agent may be appropriately adjusted according to the number of functional groups in the structures of the pressure-sensitive adhesive resins (I) and (II). From the viewpoint of promoting the crosslinking reaction, it is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and still more preferably 0.05 to 4 parts by mass with respect to 100 parts by mass of the pressure-sensitive adhesive resins (I) and (II).

[0131] [Photoinitiator] Also, the pressure-sensitive adhesive compositions (x-2A) and (x-2B) preferably further contain a photoinitiator. By containing the photoinitiator, the curing reaction can proceed sufficiently even with relatively low-energy energy rays such as ultraviolet rays. Examples of the photoinitiator include 1-hydroxy-cyclohexyl-phenyl-ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyl phenyl sulfide, tetramethylthiuram monosulfide, azobisisobutyronitrile, dibenzyl, diacetyl, 8-chloroanthraquinone, and the like. These photoinitiators may be used alone or in combination of two or more. The compounding amount of the photoinitiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and still more preferably 0.05 to 2 parts by mass with respect to 100 parts by mass of the pressure-sensitive resins (I) and (II).

[0132] 〔Other Additives〕 The pressure-sensitive adhesive compositions (x-2A) and (x-2B) may contain other additives as long as the effects of the present invention are not impaired. Examples of the other additives include the same tackifiers and additives for pressure-sensitive adhesives that the pressure-sensitive adhesive layer (X1) may contain, and the preferred embodiments and contents are the same.

[0133] Further, from the viewpoint of improving the coatability to a substrate, a release sheet, etc., the pressure-sensitive adhesive compositions (x-2A) and (x-2B) may be diluted with a solvent to be in the form of a solution. Examples of the solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol, and the like. In addition, as these solvents, the solvents used in the production of the pressure-sensitive resins (I) and (II) may be used as they are, or one or more solvents other than the solvents used in the preparation may be added so that the solution of the pressure-sensitive adhesive composition can be uniformly applied.

[0134] When diluting the pressure-sensitive adhesive compositions (x-2A) and (x-2B) with a solvent, it is preferable to blend the solvent so that the solid content concentration becomes preferably 5 to 60% by mass, more preferably 10 to 45% by mass, and still more preferably 15 to 30% by mass.

[0135] The pressure-sensitive adhesive composition (x-2) can be produced by mixing a pressure-sensitive adhesive resin, a crosslinking agent, a photopolymerization initiator, other additives, etc. used as required.

[0136] 〔Physical properties, etc. of the pressure-sensitive adhesive layer (X2)〕 (Adhesion of the pressure-sensitive adhesive layer (X2)) The adhesion before energy ray irradiation on the adhesive surface of the pressure-sensitive adhesive layer (X2) is preferably 4.0 to 30.0 N / 25 mm, more preferably 6.0 to 27.0 N / 25 mm, still more preferably 8.0 to 24.0 N / 25 mm, and even more preferably 10.0 to 20.0 N / 25 mm. If the adhesion before energy ray irradiation on the adhesive surface of the pressure-sensitive adhesive layer (X2) is 4.0 N / 25 mm or more, unintended peeling from the adherend and displacement of the adherend during temporary fixing can be more effectively suppressed. On the other hand, if the adhesion is 30.0 N / 25 mm or less, the adhesion after energy ray irradiation can be suppressed to a low level. The adhesion after energy ray irradiation on the adhesive surface of the pressure-sensitive adhesive layer (X2) is preferably 0.01 to 2.0 N / 25 mm, more preferably 0.02 to 1.0 N / 25 mm, still more preferably 0.03 to 0.50 N / 25 mm, and even more preferably 0.05 to 0.30 N / 25 mm. If the adhesion after energy ray irradiation on the adhesive surface of the pressure-sensitive adhesive layer (X2) is 0.01 N / 25 mm or more, the unintended dropping of the object to be processed during the process can be effectively suppressed. On the other hand, if the adhesion is 2.0 N / 25 mm or less, it becomes easy to peel off without damaging the adherend.

[0137] (Shear storage modulus G'(23) of the pressure-sensitive adhesive layer (X2) at 23°C) The shear storage modulus G'(23) of the pressure-sensitive adhesive layer (X2) at 23°C is preferably 5.0×10 3 ~1.0×10 7 Pa, more preferably 1.0×10 4 ~5.0×10 6 Pa, still more preferably 5.0×10 4~1.0×10 6 Pa. When the shear storage modulus G’(23) of the pressure-sensitive adhesive layer (X2) is 5.0×10 3 Pa or more, it tends to suppress displacement of the adherend during temporary fixing, excessive sinking of the adherend into the pressure-sensitive adhesive layer (X2), etc. On the other hand, when the shear storage modulus G’(23) is 1.0×10 7 Pa or less, the adhesion to the adherend tends to improve. In addition, in this specification, the shear storage modulus G’(23) of the pressure-sensitive adhesive layer (X2) at 23°C can be measured by the same method as the shear storage modulus G’ of the pressure-sensitive adhesive layer (X1) at 23°C.

[0138] (Thickness of the pressure-sensitive adhesive layer (X2) at 23°C) The thickness of the pressure-sensitive adhesive layer (X2) at 23°C is preferably 5 to 150 μm, more preferably 8 to 100 μm, still more preferably 12 to 70 μm, and even more preferably 15 to 50 μm. When the thickness of the pressure-sensitive adhesive layer (X2) at 23°C is 5 μm or more, sufficient adhesive force is likely to be obtained, and it tends to suppress unintentional peeling from the adherend and displacement of the adherend during temporary fixing. On the other hand, when the thickness of the pressure-sensitive adhesive layer (X2) at 23°C is 150 μm or less, the handling of the adhesive sheet tends to be easy.

[0139] <Release material> As the release material, a release sheet subjected to double-sided release treatment, a release sheet subjected to single-sided release treatment, etc. are used, and those obtained by applying a release agent on a base material for the release material can be mentioned. Examples of the base material for the release material include plastic films, papers, etc. Examples of the plastic film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; olefin resin films such as polypropylene resin and polyethylene resin, etc. Examples of the papers include high-quality paper, glassine paper, kraft paper, etc.

[0140] Examples of the release agent include rubber-based elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins; long-chain alkyl resins, alkyd resins, fluorine resins, and the like. The release agent may be used alone or in combination of two or more.

[0141] The thickness of the release material is preferably 10 to 200 μm, more preferably 20 to 150 μm, and even more preferably 35 to 80 μm.

[0142] <Method for manufacturing an adhesive sheet> For the method for manufacturing the adhesive sheet used in one aspect of the present invention, it is preferable to appropriately select a method suitable for the type of materials used and the like. Hereinafter, a method for manufacturing an adhesive sheet in which the adhesive layer (X1) is formed using the above polymerizable composition (x-1A) or adhesive composition (x-1B) will be described. However, the method for manufacturing the adhesive sheet used in one aspect of the present invention is not limited to these methods.

[0143] - Method using the polymerizable composition (x-1A)- When the polymerizable composition (x-1A) is used to form the adhesive layer (X1), the adhesive sheet used in one aspect of the present invention is preferably manufactured by a method including a step of irradiating the polymerizable composition (x-1A) with an energy ray to form a polymer of the energy ray-polymerizable component. More specifically, it preferably includes the following steps IA to IIIA. Step IA: A step of forming a polymerizable composition layer made of the polymerizable composition (x-1A) on one surface side of the base material (Y). Step IIA: A step of irradiating the polymerizable composition layer with an energy ray to form a polymer of the energy ray-polymerizable component and forming an adhesive layer (X1) containing the polymer and the thermally expandable particles. Step IIIA: A step of forming an adhesive layer (X2) on the other surface side of the base material (Y). Hereinafter, steps IA to IIIA will be described.

[0144] 〔Step IA〕 The engineering IA is not particularly limited as long as it is a process of forming a polymerizable composition layer on one surface side of the base material (Y), but it preferably includes the following processes IA-1 to IA-3. Process IA-1: A process of forming a polymerizable composition layer by applying a polymerizable composition (x-1A) on the release-treated surface of a release material Process IA-2: A process of performing first energy ray irradiation on the polymerizable composition layer to preliminarily polymerize the energy ray polymerizable component in the polymerizable composition layer Process IA-3: A process of attaching the base material (Y) to the polymerizable composition layer after the first energy ray irradiation

[0145] (Process IA-1) Process IA-1 is a process of forming a polymerizable composition layer by applying a polymerizable composition (x-1A) on the release-treated surface of a release material. In Process IA-1, examples of the method of applying the polymerizable composition (x-1A) to the release material include a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, etc.

[0146] As described above, the polymerizable composition (x-1A) is preferably a solventless polymerizable composition. When the polymerizable composition (x-1A) is a solventless polymerizable composition, it is not necessary to perform a solvent heating and drying process in this step. On the other hand, when the polymerizable composition (x-1A) contains a solvent within a range not contrary to the object of the present invention, heating and drying may be performed after applying the polymerizable composition (x-1A), but the heating temperature in that case should be less than the expansion start temperature (t) of the thermally expandable particles.

[0147] (Process IA-2) Process IA-2 is a process of performing first energy ray irradiation on the polymerizable composition layer formed in Process IA-1 to preliminarily polymerize the energy ray polymerizable component in the polymerizable composition layer. The first energy ray irradiation is carried out for the purpose of increasing the viscosity of the polymerizable composition by preliminarily polymerizing the energy ray polymerizable component and improving the shape maintainability of the polymerizable composition layer. In the first energy ray irradiation, the energy ray polymerizable component is not completely polymerized but only pre-polymerized. This can improve the adhesion between the polymerizable composition layer and the substrate (Y) in step IA-3.

[0148] As the energy ray used for the first energy ray irradiation in step IA-2, among those described above, ultraviolet rays that are easy to handle are preferable. The illuminance of the ultraviolet ray in the first energy ray irradiation is preferably 70 to 250 mW / cm 2 , more preferably 100 to 200 mW / cm 2 , still more preferably 130 to 170 mW / cm 2 . Also, the light quantity of the ultraviolet ray in the first energy ray irradiation is preferably 40 to 200 mJ / cm 2 , more preferably 60 to 150 mJ / cm 2 , still more preferably 80 to 120 mJ / cm 2 . The first energy ray irradiation may be performed once or divided into a plurality of times. Also, in order to suppress the temperature rise of the polymerizable composition layer due to polymerization heat or the like, it may be performed while cooling the polymerizable composition layer.

[0149] (Step IA-3) Step IA-3 is a step of attaching the substrate (Y) to the polymerizable composition layer after the first energy ray irradiation. The method of attaching the substrate (Y) to the polymerizable composition layer is not particularly limited, and examples thereof include a method of laminating the substrate (Y) on the exposed surface of the polymerizable composition layer. The lamination may be performed while heating or without heating, but from the viewpoint of suppressing the expansion of the thermally expandable particles, it is preferably performed without heating. At this time, the polymerizable composition layer pre-polymerized by the first energy ray irradiation has good adhesion to the substrate (Y) even without heating.

[0150] [Step IIA] Step IIA is a step of forming a polymer of an energy ray-polymerizable component by irradiating the polymerizable composition layer formed in Step IA with an energy ray, and forming an adhesive layer (X1) containing the polymer and thermally expandable particles.

[0151] Here, when the first energy ray irradiation is performed in Step IA, the energy ray irradiation in Step IIA is the second energy ray irradiation performed on the polymerizable composition layer after preliminary polymerization. Unlike the first energy ray irradiation, the energy ray irradiation in Step IIA is preferably performed to such an extent that even if further irradiated with an energy ray, the polymerization of the energy ray-polymerizable component hardly proceeds. By the energy ray irradiation in Step IIA, the polymerization of the energy ray-polymerizable component proceeds, and a polymer of the energy ray-polymerizable component constituting the adhesive layer (X1) is formed.

[0152] Among the above-mentioned energy rays, ultraviolet rays that are easy to handle are preferable as the energy rays used for the energy ray irradiation in Step IIA. The illuminance of the ultraviolet ray in the energy ray irradiation in Step IIA is preferably 100 to 350 mW / cm 2 、more preferably 150 to 300 mW / cm 2 、even more preferably 180 to 250 mW / cm 2 is. The light quantity of the ultraviolet ray in the energy ray irradiation in Step IIA is preferably 500 to 4,000 mJ / cm 2 、more preferably 1,000 to 3,000 mJ / cm 2 、even more preferably 1,500 to 2,500 mJ / cm 2 is. The energy ray irradiation in Step IIA may be performed once or divided into a plurality of times. Further, in order to suppress the temperature rise of the polymerizable composition layer due to polymerization heat or the like, it may be performed while cooling the polymerizable composition layer.

[0153] In addition, when Step IA includes the above-described Steps IA-1 to IA-3, the polymerizable composition layer is obtained as an intermediate layer of a laminate in which a release material, the polymerizable composition layer, and a substrate (Y) are laminated in this order. At this time, the second energy ray irradiation may be performed on the laminate having such a configuration. In that case, from the viewpoint of enabling sufficient irradiation of the energy rays to the polymerizable composition layer present as the intermediate layer of the laminate, it is preferable that one or more selected from the release material and the substrate (Y) have energy ray transmissivity.

[0154] In any of the steps included in the above-described Steps IA and IIA, from the viewpoint of suppressing the expansion of the thermally expandable particles, it is preferable not to include a step of heating the polymerizable composition. Here, the "heating" means, for example, intentionally heating during drying, lamination, etc., and does not include a temperature rise due to heat applied to the polymerizable composition by energy ray irradiation, polymerization heat generated by polymerization of the energy ray-polymerizable composition, etc. When including a step of heating the polymerizable composition as necessary, the heating temperature is preferably "a temperature lower than the expansion start temperature (t)", more preferably "the expansion start temperature (t) - 5°C" or lower, still more preferably "the expansion start temperature (t) - 10°C" or lower, and even more preferably "the expansion start temperature (t) - 15°C" or lower. Further, when the temperature of the polymerizable composition rises unintentionally, it is preferable to cool the temperature of the polymerizable composition so as to be within the above temperature range.

[0155] 〔Step IIIA〕 Step IIIA is a step of forming an adhesive layer (X2) on the other surface side of the substrate (Y). The adhesive layer (X2) preferably includes the following Steps IIIA-1 and IIIA-2. Step IIIA-1: A step of applying an adhesive composition (x-2) to one surface of a release material to form an adhesive layer (X2) Step IIIA-2: A step of attaching the adhesive layer (X2) formed in Step IIIA-1 to the other surface side of the substrate (Y)

[0156] In Step IIIA-1, as a method for applying the pressure-sensitive adhesive composition (x-2), the same methods as those described as methods for applying the polymerizable composition (x-1A) in Step IA-1 can be mentioned. Further, when the pressure-sensitive adhesive layer (X2) contains a solvent, it may include a step of drying the coating film after applying the pressure-sensitive adhesive composition (x-2). As described above, from the viewpoint of suppressing the phenomenon in which the pressure-sensitive adhesive layer is divided and peeled off along with the two release materials, it is preferable that the release material used in Step IIIA-1 and the release material used in Step IA-1 are designed to have different release forces.

[0157] In Step IIIA-2, as a method for attaching the pressure-sensitive adhesive layer (X2) to the substrate (Y), the same methods as those for attaching the substrate (Y) to the polymerizable composition layer in Step IA-3 can be mentioned, and the preferred embodiments are also the same.

[0158] - Method using the pressure-sensitive adhesive composition (x-1B)- When using the above-described pressure-sensitive adhesive composition (x-1B) to form the pressure-sensitive adhesive layer (X1), the pressure-sensitive adhesive sheet used in one embodiment of the present invention can be manufactured, for example, by a method including the following Steps IB to IIIB. · Step IB: A step of applying the pressure-sensitive adhesive composition (x-1B) on the release-treated surface of the release material to form a coating film, drying the coating film, and forming the pressure-sensitive adhesive layer (X1). · Step IIB: A step of applying the pressure-sensitive adhesive composition (x-2), which is a forming material of the pressure-sensitive adhesive layer, on the release-treated surface of another release material to form a coating film, drying the coating film, and forming the pressure-sensitive adhesive layer (X2). · Step IIIB: A step of bonding the pressure-sensitive adhesive layer (X1) formed in Step IB to one surface of the substrate, and bonding the pressure-sensitive adhesive layer (X2) formed in Step IIB to the other surface of the substrate. Preferred embodiments of the methods and conditions for applying, drying, and bonding the pressure-sensitive adhesive composition in each step are the same as the preferred embodiments of the methods and conditions described in the method using the above-described polymerizable composition (x-1A).

[0159] [Each Step of the Method for Manufacturing a Semiconductor Device] Next, each step included in the method for manufacturing a semiconductor device according to one aspect of the present invention will be described in order with reference to the drawings. In the following description, an example in the case of using a semiconductor wafer as an object to be processed will be mainly described, but the same applies to other objects to be processed.

[0160] <Step 1> Step 1 is a step of attaching an object to be processed to the adhesive layer (X2) of the adhesive sheet and attaching a support to the adhesive layer (X1). FIG. 2 shows a cross-sectional view for explaining a step of attaching a semiconductor wafer W to the adhesive layer (X2) of the adhesive sheet 1a and attaching a support 2 to the adhesive layer (X1). The semiconductor wafer W is attached so that the surface W1, which is the circuit surface, faces the adhesive layer (X2) side. The semiconductor wafer W may be a silicon wafer, or may be a wafer such as gallium arsenide, silicon carbide, sapphire, lithium tantalate, lithium niobate, gallium nitride, indium phosphide, or a glass wafer. The thickness of the semiconductor wafer W before grinding is usually 500 to 1,000 μm. The circuit on the surface W1 of the semiconductor wafer W can be formed by a conventionally widely used method such as an etching method or a lift-off method.

[0161] The material of the support 2 may be appropriately selected in consideration of required characteristics such as mechanical strength and heat resistance according to the type of the object to be processed, the processing content, etc. Examples of the material of the support 2 include metal materials such as SUS; non-metallic inorganic materials such as glass and silicon wafers; resin materials such as epoxy resins, ABS resins, acrylic resins, engineering plastics, super engineering plastics, polyimide resins, and polyamideimide resins; composite materials such as glass epoxy resins, etc. Among these, SUS, glass, and silicon wafers are preferred. Examples of the above engineering plastics include nylon, polycarbonate (PC), polyethylene terephthalate (PET), etc. Examples of the above-mentioned super engineering plastics include polyphenylene sulfide (PPS), polyethersulfone (PES), polyetheretherketone (PEEK), and the like.

[0162] The support 2 is preferably attached to the entire adhesive surface of the adhesive layer (X1). Therefore, the area of the surface of the support 2 on the side attached to the adhesive surface of the adhesive layer (X1) is preferably equal to or larger than the area of the adhesive surface of the adhesive layer (X1). Also, the surface of the support 2 on the side attached to the adhesive surface of the adhesive layer (X1) is preferably flat. The shape of the support 2 is not particularly limited, but is preferably plate-shaped. The thickness of the support 2 may be appropriately selected in consideration of the required characteristics, but is preferably 20 μm or more and 50 mm or less, more preferably 60 μm or more and 20 mm or less.

[0163] <Process 2> Process 2 is a process of performing one or more processing operations selected from grinding processing and singulation processing on the object to be processed. Examples of one or more processing operations selected from grinding processing and singulation processing include grinding processing using a grinder or the like; singulation processing by a blade dicing method, a laser dicing method, a stealth dicing (registered trademark) method, a blade tip dicing method, a stealth tip dicing method, and the like. Among these, singulation processing by the stealth dicing method, grinding processing and singulation processing by the blade tip dicing method, and grinding processing and singulation processing by the stealth tip dicing method are preferable, and grinding processing and singulation processing by the blade tip dicing method and grinding processing and singulation processing by the stealth tip dicing method are more preferable.

[0164] The stealth dicing method is a method of forming a modified region inside a semiconductor wafer by irradiating with laser light, and then singulating the semiconductor wafer starting from the modified region. The modified region formed in the semiconductor wafer is a portion embrittled by multi-photon absorption. When the semiconductor wafer is expanded and stressed in a direction parallel to the wafer surface and in the direction in which the wafer is expanded, cracks extend from the modified region toward the front and back surfaces of the semiconductor wafer, and the semiconductor wafer is singulated into semiconductor chips. That is, the modified region is formed along the dividing line when singulating. The modified region is formed inside the semiconductor wafer by irradiating laser light focused inside the semiconductor wafer. The incident surface of the laser light may be the front surface or the back surface of the semiconductor wafer. Also, the laser light incident surface may be the surface to which the adhesive sheet is attached. In that case, the laser light is irradiated onto the semiconductor wafer through the adhesive sheet.

[0165] The blade tip dicing method is also called the DBG method (Dicing Before Grinding). The blade tip dicing method is a method of forming a groove in a semiconductor wafer in advance along a line to be divided at a depth shallower than its thickness, and then singulating the semiconductor wafer while thinning it by back grinding until the grinding surface reaches at least the groove. The groove reached by the grinding surface becomes a cut penetrating the semiconductor wafer, and the semiconductor wafer is divided by the cut and singulated into semiconductor chips. The groove formed in advance is usually provided on the surface (circuit surface) of the semiconductor wafer, and can be formed, for example, by dicing using a conventionally known wafer dicing apparatus equipped with a dicing blade.

[0166] The stealth front dicing method is also called the SDBG method (Stealth Dicing Before Grinding). Similar to the stealth dicing method, the stealth front dicing method is a method of forming a modified region inside a semiconductor wafer by irradiating a laser beam, and using the modified region as a starting point for division to fragment the semiconductor wafer. However, it is different from the stealth dicing method in that the semiconductor wafer is thinned while performing a grinding process and the semiconductor wafer is fragmented into semiconductor chips. Specifically, while back-grinding the semiconductor wafer having the modified region to thin it, cracks are extended toward the bonding surface with the adhesive layer of the semiconductor wafer starting from the modified region by the pressure applied to the semiconductor wafer at that time, and the semiconductor wafer is fragmented into semiconductor chips. Note that the grinding thickness after forming the modified region may be the thickness reaching the modified region, but even if it does not strictly reach the modified region, it may be ground to a position close to the modified region and cut by the processing pressure of a grinding wheel or the like. The semiconductor chips fragmented by the SDBG process are in a state of being in contact with each other, and are likely to cause a so-called chipping phenomenon in which the outer edge is finely chipped by vibration. Therefore, the method for manufacturing a semiconductor device according to one aspect of the present invention, which can suppress vibration by firmly fixing to a support, is particularly suitable for the SDBG method.

[0167] When fragmenting the semiconductor wafer W by the blade front dicing method, it is preferable to previously form grooves on the surface W1 of the semiconductor wafer W attached to the adhesive layer (X2) in step 1. On the other hand, when fragmenting the semiconductor wafer W by the stealth front dicing method, a modified region may be previously formed by irradiating the semiconductor wafer W attached to the adhesive layer (X2) with a laser beam in step 1, or a modified region may be formed by irradiating the semiconductor wafer W attached to the adhesive layer (X2) with a laser beam.

[0168] FIG. 3 shows a cross-sectional view for explaining the step of forming a plurality of modified regions 4 on the semiconductor wafer W attached to the adhesive layer (X2) using the laser beam irradiation device 3. The laser light is irradiated from the back surface W2 side of the semiconductor wafer W, and a plurality of modified regions 4 are formed in the semiconductor wafer W at substantially equal intervals.

[0169] FIG. 4 shows a cross-sectional view for explaining a process of thinning the semiconductor wafer W and singulating it into a plurality of semiconductor chips CP by scribing starting from the modified region 4 while grinding the back surface W2 of the semiconductor wafer W on which the modified region 4 is formed with a grinder 5. The semiconductor wafer W in which the modified region 4 is formed is ground on its back surface W2 in a state where, for example, the support 2 supporting the semiconductor wafer W is fixed on a fixed table such as a chuck table.

[0170] The thickness of the semiconductor chip CP after grinding is preferably 5 to 100 μm, more preferably 10 to 45 μm. Further, when performing the grinding process and the singulation process by the stealth dicing method, it becomes easier to set the thickness of the semiconductor chip CP obtained by grinding to 50 μm or less, more preferably 10 to 45 μm. The size of the semiconductor chip CP after grinding in plan view is preferably less than 600 mm 2 more preferably less than 400 mm 2 even more preferably less than 300 mm 2 and less. Note that the plan view means viewing in the thickness direction. The shape of the semiconductor chip CP after singulation in plan view may be square or may be an elongated shape such as a rectangle.

[0171] <Process 3> Process 3 is a process of attaching a thermosetting film to the surface of the object to be processed that has been subjected to the above processing, on the side opposite to the adhesive layer (X2). FIG. 5 shows a cross-sectional view for explaining a process of attaching a thermosetting film 6 provided with a support sheet 7 to the surface of a plurality of semiconductor chips CP obtained by performing the above processing, on the side opposite to the adhesive layer (X2).

[0172] The thermosetting film 6 is a film having thermosetting properties obtained by forming a resin composition containing at least a thermosetting resin, and is used as an adhesive when mounting a semiconductor chip CP on a substrate. The thermosetting film 6 may contain, if necessary, a curing agent for the thermosetting resin, a thermoplastic resin, an inorganic filler, a curing accelerator, etc. As the thermosetting film 6, for example, a thermosetting film generally used as a die bonding film, a die attach film, etc. can be used. The thickness of the thermosetting film 6 is not particularly limited, but is usually 1 to 200 μm, preferably 3 to 100 μm, more preferably 5 to 50 μm. The support sheet 7 may be any that can support the thermosetting film 6, and examples include resins, metals, paper materials, etc. such as the base material (Y) of the pressure-sensitive adhesive sheet used in one aspect of the present invention.

[0173] As a method of attaching the thermosetting film 6 to a plurality of semiconductor chips CP, for example, a method by lamination can be mentioned. Lamination may be performed while heating or without heating. When performing lamination while heating, the heating temperature is preferably "a temperature lower than the expansion start temperature (t)", more preferably "expansion start temperature (t) - 5°C" or lower, still more preferably "expansion start temperature (t) - 10°C" or lower, and even more preferably "expansion start temperature (t) - 15°C" or lower, from the viewpoints of suppressing the expansion of the thermally expandable particles and suppressing the thermal change of the adherend.

[0174] <Step 4> Step 4 is a step of heating the pressure-sensitive adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) to separate the adhesive layer (X1) from the support. FIG. 6 shows a cross-sectional view for explaining the step of heating the pressure-sensitive adhesive sheet 1a to separate the adhesive layer (X1) from the support 2.

[0175] The heating temperature in Step 4 is equal to or higher than the expansion start temperature (t) of the thermally expandable particles, preferably "a temperature higher than the expansion start temperature (t)", more preferably "the expansion start temperature (t) + 2°C" or higher, still more preferably "the expansion start temperature (t) + 4°C" or higher, and even more preferably "the expansion start temperature (t) + 5°C" or higher. Also, from the viewpoints of energy conservation and suppressing thermal changes in the adherend during heat peeling, the heating temperature in Step 4 is preferably "the expansion start temperature (t) + 50°C" or lower, more preferably "the expansion start temperature (t) + 40°C" or lower, and still more preferably "the expansion start temperature (t) + 20°C" or lower. From the viewpoint of suppressing thermal changes in the adherend, the heating temperature in Step 4 is preferably 120°C or lower, more preferably 115°C or lower, still more preferably 110°C or lower, and even more preferably 105°C or lower within the range equal to or higher than the expansion start temperature (t).

[0176] <Step 5> Step 5 is a step of irradiating the adhesive layer (X2) with energy rays to separate the adhesive layer (X2) from the object to be processed. FIG. 7 shows a cross-sectional view for explaining the step of separating the adhesive layer (X2) from a plurality of semiconductor chips CP. Since the adhesive layer (X2) is cured by irradiation with energy rays and the adhesive force decreases, the object to be processed and the adhesive layer (X2) can be easily separated by irradiation with energy rays. Among the energy rays used for the energy ray irradiation in Step 5, ultraviolet rays, which are easy to handle, are preferable. The illuminance and light quantity of the ultraviolet rays may be those that irradiate an illuminance and light quantity at which the adhesion between the adhesive layer (X2) and the object to be processed becomes sufficiently low. For example, the illuminance of the ultraviolet rays is preferably 100 to 400 mW / cm 2 , more preferably 150 to 350 mW / cm 2 , still more preferably 180 to 300 mW / cm 2 and the light quantity of the ultraviolet rays is preferably 100 to 2,000 mJ / cm 2 , more preferably 200 to 1,000 mJ / cm 2 , still more preferably 300 to 500 mJ / cm 2It is. The energy beam may be irradiated from any direction as long as it can cure the adhesive layer (X2). However, from the viewpoint of efficiently curing, it is preferably irradiated from the side of the adhesive layer (X1). At this time, from the viewpoint of enabling sufficient irradiation of the energy beam to the adhesive layer (X2), the base material (Y) and the adhesive layer (X1) preferably have energy beam transmissibility.

[0177] Through the above steps 1 to 5, a plurality of semiconductor chips CP attached to the thermosetting film 6 are obtained. Next, it is preferable to divide the thermosetting film 6 to which a plurality of semiconductor chips CP are attached into the same shape as the semiconductor chips CP to obtain semiconductor chips CP with the thermosetting film 6. As a method for dividing the thermosetting film 6, for example, methods such as laser dicing using a laser beam, expansion, and fusing can be applied. FIG. 8 shows a semiconductor chip CP with a thermosetting film 6 divided into the same shape as the semiconductor chip CP.

[0178] The semiconductor chip CP with the thermosetting film 6 is further, if necessary, subjected to an expansion process for widening the interval between the semiconductor chips CP, a rearrangement process for arranging the plurality of semiconductor chips CP with widened intervals, an inversion process for inverting the front and back of the plurality of semiconductor chips CP, etc., and then attached (die attach) to the substrate from the side of the thermosetting film 6. Thereafter, the semiconductor chip and the substrate can be fixed by thermally curing the thermosetting film 6.

Example

[0179] The present invention will be specifically described by the following examples, but the present invention is not limited to the following examples. In the following description, the "non-expandable adhesive layer (X1')" means an adhesive layer that does not contain thermally expandable particles, and the adhesive layer that does not contain thermally expandable particles prepared for measuring the shear storage modulus G' corresponds to the non-expandable adhesive layer (X1'). The physical property values in the following examples are values measured by the following methods.

[0180] [Weight-average molecular weight (Mw)] Using a gel permeation chromatograph (manufactured by Tosoh Corporation, product name "HLC-8020"), measurements were taken under the following conditions, and values measured in terms of standard polystyrene were used. (Measurement conditions) · Column: A series of columns "TSK guard column HXL-L", "TSK gel G2500HXL", "TSK gel G2000HXL", and "TSK gel G1000HXL" (all manufactured by Tosoh Corporation) connected in sequence · Column temperature: 40 °C · Developing solvent: Tetrahydrofuran · Flow rate: 1.0 mL / min

[0181] [Thickness of each layer] Measured using a constant-pressure thickness measuring instrument (model number: "PG-02J", manufactured by Techlock Co., Ltd., conforming to JIS K6783, Z1702, and Z1709 standards).

[0182] [Average particle diameter (D 50 ) of the thermally expandable particles, 90% particle diameter (D 90 )] Using a laser diffraction particle size distribution analyzer (e.g., manufactured by Malvern, product name "Mastersizer 3000"), the particle distribution of the thermally expandable particles before expansion at 23 °C was measured. Then, the particle diameters corresponding to a cumulative volume frequency of 50% and 90% calculated from the smaller particle diameters of the particle distribution were defined as the "average particle diameter (D 50 ) of the thermally expandable particles" and the "90% particle diameter (D 90 ) of the thermally expandable particles", respectively.

[0183] [Storage elastic modulus E' of the base material (Y)] Using a base material (Y) cut to 5 mm in length and 30 mm in width as a test sample, the storage modulus E' at a predetermined temperature was measured using a dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name "DMAQ800") under the conditions of a test start temperature of 0 °C, a test end temperature of 200 °C, a heating rate of 3 °C / min, a frequency of 1 Hz, and an amplitude of 20 μm.

[0184] [Shear storage modulus G'(23) of the adhesive layer (X1) at 23 °C] A test sample was prepared by making the adhesive layer (X1) 8 mm in diameter and 3 mm in thickness. Using a viscoelasticity measuring device (manufactured by Anton Paar, device name "MCR300"), the shear storage modulus G'(23) at 23 °C was measured by the torsional shear method under the conditions of a test start temperature of 0 °C, a test end temperature of 300 °C, a heating rate of 3 °C / min, and a frequency of 1 Hz.

[0185] [Shear storage modulus G' of the non-expandable adhesive layer (X1')] In order to measure the shear storage modulus G' excluding the influence of the thermally expandable particles, in each production example, a non-expandable adhesive layer (X1') having the same configuration as the adhesive layer (X1) except for not containing thermally expandable particles was prepared as a test sample for measuring the shear storage modulus corresponding to the adhesive layer (X1) of each production example, and its shear storage modulus G' was measured. A test sample was prepared by making the non-expandable adhesive layer (X1') 8 mm in diameter and 3 mm in thickness. Using a viscoelasticity measuring device (manufactured by Anton Paar, device name "MCR300"), the shear storage modulus G'(23) at 23 °C and the shear storage modulus G'(t) at the expansion start temperature (t) of the thermally expandable particles were measured by the torsional shear method under the conditions of a test start temperature of 0 °C, a test end temperature of 300 °C, a heating rate of 3 °C / min, and a frequency of 1 Hz. Note that the expansion start temperature (t) of the thermally expandable particles of the non-expandable adhesive layer (X1') which is a test sample for measuring the shear storage modulus means the expansion start temperature (t) of the thermally expandable particles contained in the adhesive layer (X1) of the production example corresponding to the test sample for measuring the shear storage modulus. In this production example, it means 88 °C as described later.

[0186] Synthesis Example 1 (Synthesis of Urethane Acrylate-based Prepolymer) 100 parts by mass of polypropylene glycol having a mass average molecular weight (Mw) of 3,000 (in terms of solid content; the same shall apply hereinafter), 4 parts by mass of hexamethylene diisocyanate, and 0.02 parts by mass of dioctyltin dilaurate were mixed and stirred at 80 °C for 6 hours to obtain a reaction product. When the IR spectrum of the obtained reaction product was measured by infrared spectroscopy, it was confirmed that the isocyanate groups had almost disappeared. Thereafter, 1 part by mass of 2-isocyanatoethyl acrylate was mixed with the entire amount of the obtained reaction product and stirred at 80 °C for 3 hours to obtain a urethane acrylate-based prepolymer. When the IR spectrum of the obtained urethane acrylate-based prepolymer was measured by infrared spectroscopy, it was confirmed that the isocyanate groups had almost disappeared. The mass average molecular weight (Mw) of the obtained urethane acrylate-based prepolymer was 25,000.

[0187] [Manufacture of Pressure-sensitive Adhesive Sheet] Production Examples 1 to 3 (Manufacture of Polymerizable Composition) Each component described in Table 1 was mixed in the blending composition described in Table 1 to obtain a solvent-free polymerizable composition. The details of each component described in Table 1 are as follows. [Polymerizable Vinyl Monomer] 2EHA: 2-Ethylhexyl Acrylate ((a1-1) Component) IBXA: Isobornyl Acrylate ((a1-2) Component) HEA: 2-Hydroxyethyl Acrylate ((a1-3) Component) 4HBA: 4-Hydroxybutyl Acrylate ((a1-3) Component) [Polyfunctional (Meth)acrylate Monomer] Trifunctional Monomer: Ethylene Oxide-modified Triacrylate of Isocyanuric Acid ((a1-4) Component) [Polyfunctional (Meth)acrylate Prepolymer] Urethane Acrylate-based Prepolymer: Prepared in Synthesis Example 1 ((a2) Component) Polyacrylic acrylate prepolymer: "KANEKA XMAP (registered trademark) RC100C" (manufactured by Kaneka Corporation, a polyacrylic prepolymer having acryloyl groups at both ends, mass average molecular weight (Mw): 21,500) ((a2) component) [Photoinitiator] 1-Hydroxycyclohexyl phenyl ketone [Thermally expandable particles] Manufactured by AkzoNobel, product name "Expancel (registered trademark) 031-40" (DU type), expansion start temperature (t) = 88°C, average particle diameter (D 50 ) = 12.6 μm, 90% particle diameter (D 90 ) = 26.2 μm Note that "-" in the "Composition of the pressure-sensitive adhesive layer (X1) or the non-expandable pressure-sensitive adhesive layer (X1')" in Table 1 means that the component was not blended.

[0188] (Production of the pressure-sensitive adhesive sheet) Using the solventless polymerizable composition produced above, a pressure-sensitive adhesive sheet was produced by the following procedure. The solventless polymerizable composition was applied onto the release-treated surface of a polyethylene terephthalate (PET) release film (manufactured by Lintec Corporation, product name "SP-PET382150", thickness: 38 μm) to form a polymerizable composition layer. The polymerizable composition layer was subjected to preliminary polymerization by irradiating ultraviolet rays under the conditions of an illuminance of 150 mW / cm 2 and a light amount of 100 mJ / cm 2 . Note that the thickness of the polymerizable composition layer was adjusted so that the thickness of the resulting pressure-sensitive adhesive layer (X1) would be the thickness shown in Table 2. Next, a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., Cosmo Shine (registered trademark), product number "A4300", thickness: 50 μm) as the base material (Y) was attached to the exposed surface of the polymerizable composition layer to obtain a laminate in which the release film, the polymerizable composition layer, and the base material (Y) were laminated in this order. Note that the storage elastic modulus E'(23) of the base material (Y) at 23°C was 3.0×10 9 Pa, and the storage elastic modulus E'(t) of the base material (Y) at the expansion start temperature (t) of the thermally expandable particles was 2.4×10 9 Pa. With respect to the laminate obtained above, from the release film side, ultraviolet rays were irradiated under the conditions of an illuminance of 200 mW / cm 2 and a light quantity of 2,000 mJ / cm 2 (irradiated 4 times at 500 mJ / cm 2 ) to form the pressure-sensitive adhesive layer (X1), and a pressure-sensitive adhesive sheet in which the release film, the pressure-sensitive adhesive layer (X1), and the base material (Y) were laminated in this order was obtained. Note that the above illuminance and light quantity during ultraviolet irradiation are values measured using an illuminance and light quantity meter (manufactured by EIT, product name "UV Power Puck II").

[0189] Next, the following evaluations were performed on the pressure-sensitive adhesive sheets produced in each example. The evaluation results are shown in Table 2.

[0190] [Measurement of the adhesive force of the pressure-sensitive adhesive layer (X1) at 23°C before thermal expansion] The release film was removed from the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet cut into 25 mm × 250 mm, and the surface of the exposed pressure-sensitive adhesive layer (X1) was bonded to the mirror surface of a silicon mirror wafer with a 2 kg rubber roller based on JIS Z0237:2000, and then left standing in an environment of 23°C and 50% RH (relative humidity) for 20 minutes immediately after that. After standing under the above conditions, in an environment of 23°C and 50% RH (relative humidity), using a tensile testing machine (manufactured by A&D Company, Ltd., product name "Tensilon (registered trademark)"), based on JIS Z0237:2000, the adhesive force was measured at a pulling speed of 300 mm / min by the 180° peeling method.

[0191] [Measurement of the adhesive force of the pressure-sensitive adhesive layer (X1) at 23°C after thermal expansion] Further, the above test sample was placed on a hot plate so that the silicon mirror wafer was on the side in contact with the hot plate and the pressure-sensitive adhesive sheet side was on the side not in contact with the hot plate, heated at 100°C, which is equal to or higher than the expansion start temperature of the thermally expandable particles, for 1 minute, left standing in a standard environment (23°C, 50% RH (relative humidity)) for 60 minutes, and then, based on JIS Z0237:2000, the adhesive force of the pressure-sensitive adhesive layer (X1) was measured at a pulling speed of 300 mm / min by the 180° peeling method. In addition, when fixing the adhesive sheet for measurement, if the adhesive force is too small and it peels off unintentionally, making it difficult to measure the adhesive force, the adhesive force is assumed to be 0 N / 25 mm.

[0192] [Evaluation of self - peeling property] The release film was removed from the adhesive layer (X1) of the adhesive sheet cut into 50 mm × 50 mm, and the surface of the exposed adhesive layer (X1) was bonded to the mirror surface of a silicon mirror wafer with a 2 kg rubber roller based on JIS Z0237:2000. The sample thus obtained was left standing for 20 minutes in an environment of 23°C and 50% RH (relative humidity) immediately afterwards, and used as a test sample. Next, the test sample was placed on a hot plate such that the silicon mirror wafer was on the side in contact with the hot plate and the adhesive sheet side was not in contact with the hot plate, and heated at 100°C, which is above the expansion start temperature of the thermally expandable particles, for a maximum of 60 seconds. The ratio (%) of the peeled area of the adhesive sheet at the time of heating for 60 seconds (peeled area × 100 / total area of the adhesive sheet) was determined and evaluated based on the following criteria. A: The adhesive sheet peeled off completely within 60 seconds. B: After heating for 60 seconds, the peeled area was 30% or more and less than 100%. C: After heating for 60 seconds, the peeled area was less than 30%. Also, for those evaluated as "A", the time (seconds) required for complete peeling was measured.

[0193]

Table 1

[0194]

Table 2

[0195] From Table 2, it can be seen that all of the pressure-sensitive adhesive sheets of Production Examples 1 to 3 can be heat-peeled at a low temperature (100°C) while having sufficient adhesive strength before heat peeling. Further, it can be seen that the adhesive strength and self-peeling property of these pressure-sensitive adhesive sheets can be adjusted by adjusting the composition of the polymerizable composition and the thickness of the pressure-sensitive adhesive layer (X1), etc.

[0196] [Manufacture of semiconductor device] Example 1 Next, a semiconductor device was manufactured by the manufacturing method of the present embodiment. Note that the double-sided pressure-sensitive adhesive sheet used in the manufacturing method of the semiconductor device was produced by the method shown below.

[0197] [Production of double-sided pressure-sensitive adhesive sheet] (1) Preparation of energy ray-curable pressure-sensitive adhesive composition (x-2) 52 parts by mass of butyl acrylate, 20 parts by mass of methyl methacrylate, and 28 parts by mass of 2-hydroxyethyl acrylate were solution-polymerized in an ethyl acetate solvent to obtain a non-energy ray-curable acrylic copolymer. To the total number of hydroxyl groups of the obtained acrylic copolymer, methacryloyloxyethyl isocyanate in an amount such that the isocyanate group number is 0.9 equivalent was added to the solution containing the acrylic copolymer and reacted to produce an energy ray-curable acrylic copolymer (1) (Mw: 1,000,000) having an energy ray-polymerizable group in the side chain. Then, with respect to 100 parts by mass of the solid content of this acrylic copolymer (1), 0.5 part by mass (solid content ratio) of an isocyanate-based crosslinking agent (product name "Coronate L", manufactured by Tosoh Corporation) as a crosslinking agent and 0.57 part by mass (solid content ratio) of 1-hydroxy-cyclohexyl-phenyl-ketone (product name "Irgacure 184", manufactured by IGM Resins) as a photopolymerization initiator were blended to prepare a solution of an energy ray-curable pressure-sensitive adhesive composition (x-2).

[0198] (2) Manufacture of double-sided pressure-sensitive adhesive sheet The pressure-sensitive adhesive sheet in which the release film, the pressure-sensitive adhesive layer (X1), and the base material (Y) produced in Production Example 1 were laminated in this order was prepared as the pressure-sensitive adhesive sheet (1). On the other hand, the energy ray-curable pressure-sensitive adhesive composition (x-2) prepared above was applied onto the release-treated surface of a polyethylene terephthalate (PET) release film (manufactured by Lintec Corporation, product name "SP-PET381031", thickness: 38 μm), dried at 100°C for 1 minute, and an adhesive layer (X2) (thickness: 20 μm) was formed on the release film. Then, the adhesive layer (X2) and the base material (Y) of the pressure-sensitive adhesive sheet (1) were bonded together to obtain a double-sided pressure-sensitive adhesive sheet in which a release film, an adhesive layer (X1), a base material (Y), an adhesive layer (X2), and a release film were laminated in this order.

[0199] 〔Manufacture of semiconductor device〕 (Process 1) Using a back grinding tape laminator (manufactured by Lintec Corporation, device name "RAD-3510F / 12"), on a table at room temperature (25°C), a wafer having a circuit surface with a diameter of 12 inches, a thickness of 730 μm, and a pattern formed thereon was laminated with the release film removed from the adhesive layer (X2) of the double-sided pressure-sensitive adhesive sheet prepared above so that the adhesive layer (X2) and the circuit surface of the wafer were in contact with each other. On the other hand, a mirror wafer (diameter: 12 inches, thickness: 750 μm), which is a support, was attached to the exposed adhesive layer (X1) after removing the release film from the adhesive layer (X1) of the double-sided pressure-sensitive adhesive sheet to obtain a laminate in which a support, a double-sided pressure-sensitive adhesive sheet, and a wafer were laminated in this order.

[0200] (Process 2) Next, using a stealth laser irradiation device (manufactured by DISCO Corporation, device name "DFL7361"), stealth laser irradiation was performed from the back surface of the wafer opposite to the circuit formation surface to form a modified region inside the wafer. Then, using a grinder / polisher (manufactured by DISCO Corporation, device name "DGP8761"), grinding was performed while exposing the back surface of the wafer to ultrapure water, and at the same time, the wafer was diced into individual chips to obtain chips with a thickness of 20 μm. During these processes, vibrations and displacements of the object to be processed due to insufficient adhesion between the double-sided pressure-sensitive adhesive sheet and the support were sufficiently suppressed.

[0201] (Step 3) Subsequently, on the back side of the diced chip, a die attach film with a support sheet (manufactured by Lintec Corporation, product name "Adwill LD01D-7") was attached using a mounter (manufactured by Lintec Corporation, product name "RAD2700") under the condition of 50 °C so that the back side of the chip and the die attach film were in contact with each other, and a laminate having a support, an adhesive sheet, a chip, a die attach film, and a support sheet in this order was obtained.

[0202] (Step 4) The above laminate was placed on a hot plate such that the support side was on the contact side with the hot plate, and heated at 100 °C, which is equal to or higher than the expansion start temperature of the thermally expandable particles, for 1 minute to separate the adhesive layer (X1) of the adhesive sheet from the support. Note that the adhesion between the adhesive layer (X1) and the support after heating decreased to such an extent that the adhesive sheet with the chip attached dropped by its own weight when the support was on the upper side and the adhesive sheet with the chip attached was on the lower side.

[0203] (Step 5) Next, from the side of the adhesive layer (X1) of the adhesive sheet exposed by separation from the support, ultraviolet rays were irradiated under the conditions of an illuminance of 230 mW / cm 2 and a light quantity of 380 mJ / cm 2 to cure the adhesive layer (X2) to reduce the adhesion, and then the adhesive layer (X2) and the chip were separated. When the surface of the chip separated from the adhesive layer (X2) was visually inspected, no contamination or glue residue was confirmed. After the die attach film was divided into the same shape as the chip, the support sheet was removed to obtain a chip with an individualized die attach film. The chip with the die attach film was attached to a substrate from the die attach film side using a die bonder, and the die attach film was thermally cured to fix the chip and the substrate, obtaining a semiconductor device.

[0204] As described above, the method for manufacturing a semiconductor device according to one aspect of the present invention is excellent in workability and productivity of an object to be processed, and it can be understood that the object to be processed is not contaminated by the thermally expandable particles and the expanded adhesive layer.

Explanation of Signs

[0205] 1a, 1b Adhesive sheet 10a, 10b Release material 2 Support 3 Laser light irradiation device 4 Modified region 5 Grinder 6 Thermosetting film 7 Support sheet W Semiconductor wafer W1 Circuit surface of semiconductor wafer and semiconductor chip W2 Back surface of semiconductor wafer and semiconductor chip CP Semiconductor chip (X1) Adhesive layer (X1) (X2) Adhesive layer (X2) (Y) Base material (Y)

Claims

1. A method for manufacturing a semiconductor device using an adhesive sheet having, in this order, an adhesive layer (X1) containing thermally expandable particles, a base material (Y), and an adhesive layer (X2) that cures upon irradiation with energy rays and has a reduced adhesive force, the method including the following steps 1 to 5, A method for manufacturing a semiconductor device, wherein the expansion start temperature (t) of the thermally expandable particles is 50 to 100°C. Step 1: A step of attaching an object to be processed to the adhesive layer (X2) of the adhesive sheet and attaching a support to the adhesive layer (X1) of the adhesive sheet Step 2: A step of performing a processing treatment on the object to be processed, the processing treatment being a dicing treatment by a stealth dicing method, a grinding treatment and a dicing treatment by a blade tip dicing method, or a grinding treatment and a dicing treatment by a stealth tip dicing method Step 3: A step of attaching a thermosetting film to the surface of the object to be processed that is opposite to the adhesive layer (X2) after the processing treatment Step 4: A step of heating the adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) of the thermally expandable particles and equal to or lower than 110°C to separate the adhesive layer (X1) from the support Step 5: A step of irradiating the adhesive layer (X2) with energy rays to separate the adhesive layer (X2) from the object to be processed

2. The method for manufacturing a semiconductor device according to claim 1, wherein the processing treatment is a grinding treatment and a dicing treatment by a stealth tip dicing method.

3. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein in step 4, the adhesive sheet is heated from the support side.

4. The method for manufacturing a semiconductor device according to any one of claims 1 to 3, wherein in step 4, the support side of the adhesive sheet is heated with a hot plate.

5. The method for manufacturing a semiconductor device according to any one of claims 1 to 4, wherein the content of the thermally expandable particles is 1 to 30% by mass with respect to the total mass (100% by mass) of the adhesive layer (X1).

6. The average particle diameter (D ５０ ) of the thermally expandable particles at 23°C is 1 to 30 µm, and the method for manufacturing a semiconductor device according to any one of claims 1 to 5.

7. The storage elastic modulus E'(23) of the base material (Y) at 23°C is 5.0×10 ７ to 5.0×10 ９ Pa, and the method for manufacturing a semiconductor device according to any one of claims 1 to 6.

8. The method for manufacturing a semiconductor device according to any one of claims 1 to 7, wherein the object to be processed is a semiconductor wafer.

9. The method for manufacturing a semiconductor device according to any one of claims 1 to 8, wherein the energy rays are ultraviolet rays.

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