TWI870458B - Semiconductor device manufacturing method - Google Patents

Abstract

The present invention relates to a method for manufacturing a semiconductor device, which is a method for manufacturing a semiconductor device using an adhesive sheet, wherein the adhesive sheet sequentially comprises an adhesive layer (X1) containing thermal expansion particles, a substrate (Y), and an adhesive layer (X2) whose adhesive force is reduced by curing by irradiating energy rays, and comprises specific steps 1 to 5.

Description

Semiconductor device manufacturing method

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

In recent years, electronic devices have been miniaturized, lightweighted, and highly functionalized. Along with this, semiconductor devices installed in electronic devices have also been miniaturized, thinned, and highly densed. In the manufacturing process of semiconductor devices, semiconductor wafers are processed into semiconductor chips through grinding steps to reduce the thickness by grinding, cutting and separating, and individualizing. At this time, the semiconductor wafer is temporarily fixed to a temporary fixing sheet and subjected to the specified processing. The semiconductor chip obtained by the specified processing is separated from the temporary fixing sheet and, if necessary, appropriately subjected to an expansion step of expanding the interval between the semiconductor chips, a rearrangement step of arranging a plurality of semiconductor chips with the expanded intervals, a reversal step of reversing the front and back of the semiconductor chip, etc., and then mounted on the substrate.

When mounting a semiconductor chip on a substrate, a step is adopted in which the semiconductor chip is attached to the substrate through a thermosetting film-like adhesive called a chip bonding film (hereinafter also referred to as "DAF"). DAF is attached to one side of a semiconductor wafer or a plurality of individual semiconductor chips, and is divided into the same shape as the semiconductor chip at the same time as the individualization of the semiconductor wafer or after being attached to the semiconductor chip. The individualized semiconductor chip with DAF is attached to the substrate from the DAF side (chip bonding), and then the semiconductor chip and the substrate are fixed by thermally curing the DAF. Therefore, the DAF must maintain the property of being bonded by pressure or heat until it is attached to the substrate, and a process is necessary to make this possible.

In order to improve the processing accuracy and processing speed when grinding or dicing a processing object such as a semiconductor wafer, a fixing means such as a temporary fixing sheet must be used to suppress vibration and positional deviation of the processing object during processing. On the other hand, after the processing is completed, from the perspective of improving productivity, the processing object is required to be quickly separated from the fixing means. Patent document 1 discloses a method of using a heat-peelable adhesive sheet for temporary fixing in cutting electronic components, wherein the heat-peelable adhesive sheet for temporary fixing has a heat-expandable adhesive layer containing heat-expandable microspheres on at least one side of a substrate. The same document states the following: This heat-peelable adhesive sheet can ensure a contact area of a specified size with the adherend when electronic components are cut, thereby preventing poor adhesion such as chip flying out. After use, if the heat-expandable microspheres are heated to expand, the contact area with the adherend is reduced, making it easy to peel off. [Prior technical document] [Patent document]

[Patent Document 1] Japanese Patent No. 3594853

[The problem that the invention wants to solve]

However, in the method disclosed in Patent Document 1, when the object to be processed is fixed to the heat-expandable adhesive layer and then cut, residues from the heat-expandable particles after peeling off by heating may adhere to the surface of the object to be processed, or the adhesive layer may deform or deteriorate due to the expansion of the heat-expandable particles, and a part of the adhesive layer may adhere to the surface of the object to be processed (so-called "residual adhesive"), thereby causing the possibility of contaminating the surface of the object to be processed.

The present invention is made in view of the above-mentioned problems, and its purpose is to provide a method for manufacturing a semiconductor device, which is free from the concern of contamination of the processing object caused by thermally expandable particles and expanded adhesive layer, and has excellent processability and productivity. [Means for solving the problem]

The inventors have found that the above-mentioned problem can be solved by a method for manufacturing a semiconductor device, which uses an adhesive sheet having an adhesive layer containing thermally expandable particles, a substrate, and an adhesive layer whose adhesive force is reduced by curing by irradiating energy rays, and includes 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, which is a method for manufacturing a semiconductor device using an adhesive sheet, wherein the adhesive sheet sequentially comprises an adhesive layer (X1) containing thermally expandable particles, a substrate (Y), and an adhesive layer (X2) whose adhesive force is reduced by curing by irradiating energy rays, and the manufacturing method comprises the following steps 1 to 5: Step 1: attaching a processing object to the adhesive layer (X2) of the adhesive sheet, and attaching a support body to the adhesive layer (X1) of the adhesive sheet; Step 2: performing one or more processing selected from grinding processing and individual chip processing on the processing object; Step 3: a step of attaching a thermosetting film to the surface of the object to be processed on the opposite side of the adhesive layer (X2); 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 as described in [1] above, wherein the processing is individualization processing by invisible dicing, grinding processing and individualization processing by blade pre-dicing, or grinding processing and individualization processing by invisible pre-dicing. [3] The method for manufacturing a semiconductor device as described in [1] or [2] above, wherein the processing is grinding and individualizing by invisible pre-cutting method. [4] The method for manufacturing a semiconductor device as described in any one of [1] to [3] above, wherein the expansion starting temperature (t) of the thermally expandable particles is 50 to 110°C. [5] The method for manufacturing a semiconductor device as described in [4] above, wherein the step 4 is a step of heating the adhesive sheet to a temperature above the expansion starting temperature (t) of the thermally expandable particles and below 120°C to separate the adhesive layer (X1) from the support body. [6] The method for producing a semiconductor device as described in any one of [1] to [5] above, wherein the content of the thermally expandable particles is 1 to 30 mass% relative to the total mass (100 mass%) of the adhesive layer (X1). [7] The method for producing a semiconductor device as described in any one of [1] to [6] above, wherein the average particle size (D ₅₀ ) of the thermally expandable particles at 23°C is 1 to 30 μm. [8] The method for producing a semiconductor device as described in any one of [1] to [7] above, wherein the storage modulus E'(23) of the substrate (Y) at 23°C is 5.0×10 ⁷ to 5.0×10 ⁹ Pa. [9] A method for manufacturing a semiconductor device as described in any one of [1] to [8] above, wherein the object to be processed is a semiconductor wafer. [10] A method for manufacturing a semiconductor device as described in any one of [1] to [9] above, wherein the energy beam is ultraviolet light. [Effect of the invention]

According to the present invention, a method for manufacturing a semiconductor device can be provided, which is free from the concern of contamination of a processing object by thermally expandable particles and an expanded adhesive layer, and has excellent processability and productivity.

In this specification, the so-called "active ingredient" refers to the components contained in the composition of interest, excluding the diluent solvent. In addition, in this specification, the mass average molecular weight (Mw) is a value converted to standard polystyrene measured by gel permeation chromatography (GPC), specifically, a value measured based on the method described in the embodiments.

In this specification, for example, "(meth)acrylic acid" means both "acrylic acid" and "methacrylic acid", and other similar terms are the same. In addition, in this specification, the lower limit and upper limit values described in stages for the preferred numerical range (for example, the range of content, etc.) can be combined independently. For example, from the description of "preferably 10~90, more preferably 30~60", "preferably the lower limit value (10)" and "preferably the upper limit value (60)" can also be combined to become "10~60".

In this specification, the term "energy beam" means an electromagnetic wave or charged particle beam that has energy quanta, and examples thereof include ultraviolet rays, radiation, electron beams, etc. Ultraviolet rays, for example, can be irradiated by using an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, etc. as an ultraviolet source. Electron beams can be irradiated by electron beam accelerators, etc. In this specification, the term "energy beam polymerization" means the property of polymerization by irradiation with energy beams.

In this manual, whether a "layer" is a "non-thermal expansion layer" or a "thermal expansion layer" is determined by the following method. When the layer to be determined contains thermal expansion particles, the layer is heated for 3 minutes at the expansion start temperature (t) of the thermal expansion particles. When the volume change rate calculated by the following formula is less than 5%, the layer is determined to be a "non-thermal expansion layer", and when it is 5% or more, the layer is determined to be a "thermal expansion layer". ・Volume change rate (%) = {(volume of the layer before heat treatment - volume of the layer before heat treatment) / volume of the layer before heat treatment} × 100 In addition, a layer that does not contain thermally expandable particles is defined as a "non-thermally expandable layer".

In this specification, the "front surface" of a semiconductor wafer and a semiconductor chip refers to the side 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 side on which no circuit is formed.

[Manufacturing method of semiconductor device] A manufacturing method of a semiconductor device according to one aspect of the present invention is a manufacturing method of a semiconductor device using an adhesive sheet, wherein the adhesive sheet sequentially comprises an adhesive layer (X1) containing thermally expandable particles, a substrate (Y), and an adhesive layer (X2) whose adhesive force is reduced by hardening by irradiating energy beams. The manufacturing method comprises the following steps 1 to 5: Step 1: Attaching a processing object to the adhesive layer (X2) of the adhesive sheet, and attaching a support body to the adhesive layer of the adhesive sheet (X1); Step 2: performing one or more processing selected from grinding and slicing on the aforementioned processing object; Step 3: attaching a thermosetting film to the surface of the processing object on the opposite side of the adhesive layer (X2) after performing the aforementioned processing; Step 4: heating the aforementioned adhesive sheet to separate the adhesive layer (X1) from the aforementioned support; Step 5: irradiating the adhesive layer (X2) with energy rays to separate the adhesive layer (X2) from the aforementioned processing object.

Here, in this specification, the so-called "semiconductor device" refers to all devices that can function by utilizing semiconductor characteristics. Examples include wafers with integrated circuits, thinned wafers with integrated circuits, chips with integrated circuits, thinned chips with integrated circuits, electronic components containing these chips, and electronic machines with the electronic components. In addition, as a "processing object" to be processed in the manufacturing method of a semiconductor device as one aspect of the present invention, although representative semiconductor wafers and semiconductor chips can be cited, there is no particular limitation as long as the manufacturing method of the present invention is applicable.

According to a method for manufacturing a semiconductor device of 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 has been hardened by irradiation with energy rays and has reduced adhesive strength. According to this method, after processing, the object to be processed can be separated from the adhesive sheet by irradiating the adhesive layer (X2) with energy rays, and the object to be processed is not contaminated by thermally expandable particles and expanded adhesive.

Furthermore, when a processing object is processed according to a method for manufacturing a semiconductor device according to one aspect of the present invention, the support body is attached to an adhesive layer (X1) containing thermally expandable particles. The adhesive layer (X1) is heated to a temperature above the expansion start temperature (t) of the thermally expandable particles, and irregularities are formed on the surface of the adhesive layer (X1) due to the expanded thermally expandable particles, and the contact area with the adherend is reduced. Due to the reduction in the contact area, the adhesion between the adhesive layer (X1) and the adherend is significantly reduced, and the adhesive sheet and the support body can be quickly separated without applying a peeling force, but by the weight of the adhesive sheet side itself or the weight of the adherend itself. For example, during heat peeling, by orienting the adhesive sheet with the object to be processed downward, the adhesive sheet with the object to be processed can be separated by falling from the support due to gravity. In this way, since the adhesive layer (X1) significantly reduces the adhesion to the support by heating, the adhesion before heat peeling can be designed to be very high. Therefore, if a manufacturing method of a semiconductor device according to one aspect of the present invention is used, vibration and positional deviation of the object to be processed caused by insufficient adhesion between the adhesive sheet and the support can be suppressed, and excellent processing accuracy and processing speed can be obtained. In addition, in this specification, the state in which the adhesive sheet is peeled off from the adherend without applying a pulling and peeling force, or the state in which the adhesive sheet is peeled off, is referred to as "self-peeling". In addition, such a property is referred to as "self-peeling property".

Hereinafter, an adhesive sheet used in a method for manufacturing a semiconductor device according to one aspect of the present invention will be described first, 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.

[Adhesive sheet] The adhesive sheet used in one embodiment of the present invention is an adhesive sheet having, in order, an adhesive layer (X1) containing thermally expandable particles, a base material (Y), and an adhesive layer (X2) whose adhesive force is reduced by curing by irradiation with energy rays. The adhesive sheet used in one embodiment of the present invention may have a release material on the adhesive surface of one of the adhesive layers (X1) and the adhesive layer (X2) or on the adhesive surfaces of both.

Next, the structure of the adhesive sheet used in one embodiment of the present invention will be described in more detail with reference to the drawings.

As an adhesive sheet used in one embodiment of the present invention, for example, a double-sided adhesive sheet 1a as shown in FIG. 1(a) can be exemplified, which has a structure in which a base material (Y) is sandwiched by an adhesive layer (X1) and an adhesive layer (X2). In addition, a double-sided adhesive sheet 1b as shown in FIG. 1(b) can be made into a structure 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).

In addition, in the double-sided adhesive sheet 1b shown in FIG1(b), when the peeling force when peeling the release material 10a from the adhesive layer (X1) and the peeling force when peeling the release material 10b from the adhesive layer (X2) are the same, if the release materials on both sides are pulled apart to peel, the adhesive layer is broken along with the two release materials, resulting in the phenomenon of being pulled apart and peeled. From the viewpoint of suppressing such a phenomenon, it is better to use two kinds of release materials designed to have different peeling forces from the adhesive layers attached to each other as the two release materials 10a and 10b.

As another embodiment of the adhesive sheet, it may be a double-sided adhesive sheet 1a as shown in FIG. 1( a) , in which the adhesive surface of one of the adhesive layer (X1) and the adhesive layer (X2) is laminated with a release material having both sides subjected to a release treatment and rolled into a roll.

The adhesive sheet used in one embodiment of the present invention may or may not have other layers between the substrate (Y) and the adhesive layer (X1). Furthermore, the adhesive sheet used in one embodiment of the present invention may or may not have other layers between the substrate (Y) and the adhesive layer (X2). However, it is preferred to directly laminate a layer that can suppress the expansion of the surface on the opposite side of the adhesive surface of the adhesive layer (X1), and it is more preferred to directly laminate the substrate (Y).

<Base material (Y)> The base material (Y) may be, for example, resin, metal, paper, etc., and may be appropriately selected depending on the purpose of the adhesive sheet used in one embodiment of the present invention.

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; fluorine resins, etc. Examples of metals include aluminum, tin, chromium, and titanium. Examples of paper materials include thin paper, medium-quality paper, high-quality paper, impregnated paper, coated paper, art paper, sulphate paper, and translucent paper (glassine paper). Among these, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferred.

These forming materials may be composed of one kind or two or more kinds may be used in combination. As a base material (Y) formed by using two or more forming materials in combination, there can be cited a method in which a paper material is laminated with a thermoplastic resin such as polyethylene, and a metal layer is formed on the surface of a resin film or sheet containing a resin. As a method for forming a metal layer, there can be cited a method in which a metal is evaporated by a PVD method such as vacuum evaporation, sputtering, ion plating, etc., and a method in which a metal foil is attached using a general adhesive.

From the perspective of improving the interlayer adhesion between the substrate (Y) and other laminated layers, the surface of the substrate (Y) may be subjected to surface treatments such as oxidation and embossing, easy-to-weld treatment, primer treatment, etc. As oxidation methods, examples include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone irradiation treatment, and ultraviolet irradiation treatment. In addition, as embossing methods, examples include sandblasting and solvent treatment.

The substrate (Y) may also contain, together with the above-mentioned resin, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a lubricant, an anti-adhesion agent, a coloring agent, etc. as a substrate additive. These substrate additives may be used alone or in combination of two or more. When the substrate (Y) contains a substrate additive together with the above-mentioned resin, the content of each substrate additive is preferably 0.0001 to 20 parts by mass, and more preferably 0.001 to 10 parts by mass, relative to 100 parts by mass of the above-mentioned resin.

The substrate (Y) is preferably a non-thermally expansive layer. When the substrate (Y) is a non-thermally expansive layer, the volume change rate (%) of the substrate (Y) calculated by the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, further preferably less than 0.1%, and even more preferably less than 0.01%.

The substrate (Y) may contain heat-expandable particles within the scope of the present invention, but preferably does not contain heat-expandable particles. When the substrate (Y) contains heat-expandable particles, the content is as small as possible, preferably less than 3% by mass, more preferably less than 1% by mass, more preferably less than 0.1% by mass, more preferably less than 0.01% by mass, and even more preferably less than 0.001% by mass relative to the total mass of the substrate (Y) (100% by mass).

[Physical properties of substrate (Y)] (Storage modulus E'(23) of substrate (Y) at 23°C) The storage modulus E'(23) of substrate (Y) at 23°C is preferably 5.0×10 ⁷ to 5.0×10 ⁹ Pa, more preferably 5.0×10 ⁸ to 4.5×10 ⁹ Pa, and further preferably 1.0×10 ⁹ to 4.0×10 ⁹ Pa. If the storage modulus E'(23) of substrate (Y) is 5.0×10 ⁷ Pa or more, it is possible to effectively suppress the expansion of the surface of the adhesive layer (X1) on the substrate (Y) side and improve the deformation resistance of the adhesive sheet. On the other hand, if the storage modulus E'(23) of the substrate (Y) is 5.0×10 ⁹ Pa or less, the handling properties of the adhesive sheet can be improved. In addition, in this specification, the storage modulus E'(23) of the substrate (Y) refers to a value measured by the method described in the embodiment.

(Storage modulus E'(t) at expansion starting temperature (t) of substrate (Y)) The storage modulus E'(t) at expansion starting temperature (t) of the thermally expandable particles of substrate (Y) is preferably 5.0×10 ⁶ ~4.0×10 ⁹ Pa, more preferably 2.0×10 ⁸ ~3.0×10 ⁹ Pa, and further preferably 5.0×10 ⁸ ~2.5×10 ⁹ Pa. If the storage modulus E'(t) of substrate (Y) is 5.0×10 ⁶ Pa or more, the expansion of the surface of the adhesive layer (X1) on the substrate (Y) side can be effectively suppressed, and the deformation resistance of the adhesive sheet can be improved. On the other hand, if the storage modulus E'(t) of the substrate (Y) is 4.0×10 ⁹ Pa or less, the handling properties of the adhesive sheet can be improved. In addition, in this specification, the storage modulus E'(t) of the substrate (Y) refers to the value measured by the method described in the embodiment.

(Thickness of substrate (Y)) The thickness of substrate (Y) is preferably 5~500μm, more preferably 15~300μm, and further preferably 20~200μm. If the thickness of substrate (Y) is 5μm or more, the deformation resistance of the adhesive sheet can be improved. On the other hand, if the thickness of substrate (Y) is 500μm or less, the operability of the adhesive sheet can be improved. In addition, in this specification, the thickness of substrate (Y) refers to the value measured by the method described in the embodiment.

<Adhesive layer (X1)> The adhesive layer (X1) is an adhesive layer containing heat-expandable particles. The adhesive layer (X1) is a layer that forms irregularities on the surface due to the expanded heat-expandable particles by heating to a temperature higher than the expansion start temperature (t) of the heat-expandable particles, thereby reducing the adhesion to the adherend. The following describes the components contained in the adhesive layer (X1).

[Thermal expansion particles] The expansion start temperature (t) of the thermal expansion particles contained in the adhesive layer (X1) is not particularly limited and can be appropriately adjusted depending on the purpose of the adhesive sheet. For example, from the perspective of suppressing the expansion of the thermal expansion particles due to the temperature rise during grinding of the object to be processed, it is preferably 50°C or more, more preferably 55°C or more, further preferably 60°C or more, and further preferably 70°C or more. On the other hand, from the perspective of suppressing the hardening of the thermosetting film attached to the object to be processed during heat peeling, it is preferably 110°C or less, more preferably 105°C or less, further preferably 100°C or less, and further preferably 95°C or less. In addition, in this manual, the expansion start temperature (t) of thermal expansion particles refers to the value measured based on the following method. [Method for measuring the expansion start temperature (t) of thermal expansion particles] In an aluminum cup with a diameter of 6.0 mm (inner diameter of 5.65 mm) and a depth of 4.8 mm, 0.5 mg of thermal expansion particles to be measured is added, and an aluminum cover (diameter of 5.6 mm, thickness of 0.1 mm) is placed from the top. The height of the sample is measured using a dynamic viscoelasticity measuring device while a force of 0.01 N is applied to the sample from the top of the aluminum cover by a pressurizer. Then, the pressure was applied with a force of 0.01N through the pressurizer, and the temperature was raised from 20°C to 300°C at a rate of 10°C/min. The displacement in the vertical direction of the pressurizer was measured, and the temperature at which the displacement in the positive direction started was defined as the expansion start temperature (t).

As the heat-expandable particles, a microencapsulated foaming agent composed of the following components is preferred: an outer shell composed of a thermoplastic resin, and an inner component encapsulated in the outer shell and vaporized by heating to a specified temperature. The thermoplastic resin constituting the outer shell of the microencapsulated foaming agent is not particularly limited, and a material and composition that can undergo state changes such as melting, dissolving, and rupture at the expansion start temperature (t) of the heat-expandable particles are appropriately selected. As the above-mentioned thermoplastic resin, for example, vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethyl methacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone, etc. can be cited. These thermoplastic resins may be used alone or in combination of two or more.

The component encapsulated in the outer shell of the microcapsule foaming agent, i.e., the inner component, may be any component that expands at the expansion start temperature (t) of the heat-expandable particles, and examples thereof include propane, propylene glycol, 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, and the like. cyclohexane, heptylcyclohexane, n-octylcyclohexane, cyclopentadecane, nonylcyclohexane, decylcyclohexane, 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, heptadecane, octadecylcyclohexane, petroleum ether, etc. Among these, from the viewpoint of lowering the expansion start temperature (t) and inhibiting the hardening of the thermosetting film attached to the object to be processed when the adhesive layer (X1) is peeled off by heating, low boiling point liquids such as propane, propylene, butene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, n-heptane, n-octane, cyclopropane, cyclobutane, petroleum ether, etc. are preferred. These inner 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 inner component.

The average particle size (D ₅₀ ) of the heat-expandable particles at 23° C. before heat expansion is preferably 1 to 30 μm, more preferably 4 to 25 μm, further preferably 6 to 20 μm, and further preferably 10 to 15 μm. In addition, the so-called average particle size (D ₅₀ ) of the heat-expandable particles is the volume median particle size (D ₅₀ ), which refers to the particle size at which the cumulative volume frequency is 50% calculated from the smallest particle size in the particle distribution of the heat-expandable particles before expansion measured using a laser diffraction particle size distribution measuring device (e.g., Mastersizer 3000 manufactured by Malvern Corporation).

The 90% particle size (D ₉₀ ) of the thermally expansive particles at 23° C. before thermal expansion is preferably 2 to 60 μm, more preferably 8 to 50 μm, further preferably 12 to 40 μm, and further preferably 20 to 30 μm. In addition, the so-called 90% particle size (D ₉₀ ) of the thermally expansive particles refers to a particle size corresponding to 90% of the cumulative volume frequency calculated from the smaller particle size in the particle distribution of the thermally expansive particles before expansion measured using the above-mentioned laser diffraction particle size distribution measuring device.

The maximum volume expansion rate when the heat-expandable particles are heated to a temperature above the expansion start temperature (t) is preferably 1.5 to 200 times, more preferably 2 to 150 times, further preferably 2.5 to 120 times, and further preferably 3 to 100 times.

The content of the heat-expandable particles is preferably 1 to 30 mass%, more preferably 2 to 25 mass%, and further preferably 3 to 20 mass%, relative to the total mass (100 mass%) of the adhesive layer (X1). If the content of the heat-expandable particles is 1 mass% or more, the peeling property during heat peeling tends to be improved. If the content of the heat-expandable particles is 30 mass% or less, the adhesive force of the adhesive layer (X1) becomes good, and the curling of the adhesive sheet during heat peeling tends to be suppressed, thereby improving the operability.

[Adhesive resin] The adhesive resin contained in the adhesive layer (X1) can be selected depending on the method of forming the adhesive layer (X1). In addition, the term "adhesive resin" in the present invention also broadly includes resins that exhibit adhesive properties by adding plasticizing components, although the composition consisting of only adhesive resins does not have adhesive properties.

As a method for forming the adhesive layer (X1), there can be exemplified 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 energy rays to form an adhesive layer (X1) containing a polymer of the energy ray polymerizable component and thermally expandable particles, a method of coating an adhesive composition containing an adhesive resin and thermally expandable particles (hereinafter, also referred to as "adhesive composition (x-1B)") to form an adhesive layer (X1), etc. Next, the preferred embodiment 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.

-Method using polymerizable composition (x-1A)- The method using 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 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) becomes a polymer formed by energy ray polymerization of the energy ray polymerizable component contained in the polymerizable composition (x-1A). Since the polymerizable composition (x-1A) is one in which the energy ray polymerizable component is high molecular weighted by subsequent energy ray polymerization, it can contain a low molecular weight energy ray polymerizable component when forming the layer. Therefore, the polymerizable composition (x-1A) can be adjusted to a viscosity suitable for coating even without using a solvent such as a diluent. As a result, when the polymerizable composition (x-1A) is used to form the adhesive layer (X1), the heat drying for removing the solvent can be omitted, and the unexpected expansion of the thermally expansive particles during the heat drying can be suppressed. Furthermore, since it is not necessary to adjust the expansion start temperature (t) of the thermally expansive particles to above the heat drying temperature, it becomes possible to reduce the expansion start temperature (t) of the thermally expansive particles. Even in the case of using a semiconductor chip with DAF that is easily thermally changed as the adherend, the thermal change of the adherend caused by heating during thermal peeling can be suppressed.

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. As energy-ray polymerizable functional groups, there can be cited those having a carbon-carbon double bond such as (meth)acryl, vinyl, allyl, etc. In addition, in this specification, functional groups such as (meth)acryl, allyl, etc., a part of which contains vinyl or substituted vinyl, and vinyl or substituted vinyl itself are collectively referred to as "vinyl-containing groups".

The polymerizable composition (x-1A) preferably contains, as energy ray polymerizable components, a monomer (a1) having an energy ray polymerizable functional group (hereinafter, also referred to as "(a1) component") and a prepolymer (a2) having an energy ray polymerizable functional group (hereinafter, also referred to as "(a2) component"). In addition, in this specification, the so-called prepolymer refers to a compound formed by polymerization of monomers, and a compound that can constitute a polymer by further polymerization.

(Monomer (a1) having energy-ray polymerizable functional groups) The monomer (a1) having energy-ray polymerizable functional groups may be any monomer having energy-ray polymerizable functional groups, and may have a alkyl group, a functional group other than energy-ray polymerizable functional groups, etc. in addition to the energy-ray polymerizable functional groups.

Examples of the alkyl group possessed by the component (a1) include aliphatic alkyl groups, aromatic alkyl groups, and groups formed by combining these groups. The aliphatic alkyl group may be a linear or branched aliphatic alkyl group, or an alicyclic alkyl group. Examples of the linear or branched aliphatic alkyl group include aliphatic alkyl groups having 1 to 20 carbon atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, tertiary butyl, sec-butyl, n-pentyl, n-hexyl, 2-ethylhexyl, n-octyl, isooctyl, n-decyl, n-dodecyl, n-myristyl, n-palmityl, and n-stearyl. Examples of the alicyclic alkyl group include alicyclic alkyl groups having 3 to 20 carbon atoms such as cyclopentyl, cyclohexyl, and isoborneol. Examples of the aromatic alkyl group include phenyl. Examples of the group formed by combining an aliphatic alkyl group and an aromatic alkyl group include phenoxyethyl and benzyl. Among these, the component (a1) is preferably 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)"), or a monomer (a1-2) having an energy ray polymerizable functional group and an alicyclic hydrocarbon group (hereinafter, also referred to as "component (a1-2)").

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 even more preferably 50 to 60% by mass relative to the total (100% by mass) of the component (a1). When the component (a1) contains the component (a1-2), its content is preferably 5 to 60% by mass, more preferably 10 to 40% by mass, and even more preferably 20 to 30% by mass relative to the total (100% by mass) of the component (a1).

As monomers having energy-ray polymerizable functional groups and functional groups other than energy-ray polymerizable functional groups, monomers having functional groups other than energy-ray polymerizable functional groups, such as hydroxyl groups, carboxyl groups, thiol groups, primary or secondary amine groups, etc., can be cited. Among these, component (a1) preferably contains a monomer (a1-3) having energy-ray polymerizable functional groups and hydroxyl groups (hereinafter, also referred to as "component (a1-3)") from the viewpoint of further improving the formability of the adhesive layer (X1). In the case where component (a1) contains component (a1-3), its content is preferably 1 to 60 mass%, more preferably 5 to 30 mass%, and further preferably 10 to 20 mass% relative to the total (100 mass%) of component (a1).

The number of energy-ray polymerizable functional groups possessed by the component (a1) may be 1 or 2 or more. In addition, from the viewpoint of further improving the self-peeling property of the adhesive layer (X1), the component (a1) preferably contains a monomer (a1-4) having 3 or more energy-ray polymerizable functional groups (hereinafter also referred to as "component (a1-4)"). In the case where the component (a1) contains the component (a1-4), its content is preferably 1 to 20% by mass, more preferably 2 to 15% by mass, and further preferably 3 to 10% by mass relative to the total (100% by mass) of the component (a1).

As a monomer having one energy ray polymerizable functional group, a monomer having one vinyl group (hereinafter also referred to as a "polymerizable vinyl monomer") is preferred. As a monomer having two or more energy ray polymerizable functional groups, a monomer having two or more (meth)acryloyl groups (hereinafter also referred to as a "multifunctional (meth)acrylate monomer") is preferred. By containing the above-mentioned compounds in the component (a1), the cohesive force of the adhesive obtained by polymerizing these can be improved, forming an adhesive layer (X1) with less contamination of the adherend after peeling.

《Polymerizable vinyl monomer》 As the polymerizable vinyl monomer, there is no particular limitation as long as it has a vinyl group, and conventionally known monomers can be appropriately used. The polymerizable vinyl monomer can be used alone or in combination of two or more.

Examples of the polymerizable vinyl monomer include compounds corresponding to the above-mentioned 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, and stearyl (meth)acrylate; compounds corresponding to the above-mentioned component (a1-2), such as cyclohexyl (meth)acrylate and isoborneol (meth)acrylate; and (meth)acrylates having no functional group other than a vinyl group in the molecule, such as phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, and polyoxyalkylene-modified (meth)acrylate. Among these, 2-ethylhexyl acrylate and isoborneol acrylate are preferred.

The polymerizable vinyl monomer may further have a functional group other than the vinyl group in the molecule. Examples of the functional group include a hydroxyl group, a carboxyl group, a thiol group, a primary or secondary amine group, etc. Among these, the polymerizable vinyl monomer having a hydroxyl group corresponding to the above-mentioned component (a1-3) is preferred. Examples of polymerizable vinyl monomers having a hydroxyl group include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and hydroxyl group-containing acrylamides such as N-hydroxymethylacrylamide and N-hydroxymethylmethacrylamide. Examples of polymerizable vinyl monomers having a carboxyl group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citric acid. Among these, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferred.

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

《Multifunctional (meth)acrylate monomer》 The multifunctional (meth)acrylate monomer is not particularly limited as long as it has two or more (meth)acrylic groups in one molecule, and conventionally known monomers can be used appropriately. The multifunctional (meth)acrylate monomer can be used alone or in combination of two or more.

Examples of the multifunctional (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, hydroxytrimethylacetic acid neopentyl glycol di(meth)acrylate, dicyclopentyl di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloyloxyethyl) isocyanurate, allyl cyclohexyl di(meth)acrylate, and isocyanurate ethylene oxide-modified diacrylate; trihydroxymethylpropane tri(meth)acrylate, diquaternary Pentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, propylene oxide-modified trihydroxymethylpropane tri(meth)acrylate, tris(acryloyloxyethyl)isocyanurate, bis(acryloyloxyethyl)hydroxyethylisocyanurate, isocyanuric acid ethylene oxide-modified triacrylate, ε-caprolactone-modified tris(acryloyloxyethyl)isocyanurate, diglycerol tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, propionic acid-modified dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate and the like, which are polyfunctional (meth)acrylate monomers corresponding to the above-mentioned component (a1-4).

《Content of component (a1)》 The total content of polymerizable vinyl monomers in the polymerizable composition (x-1A) is preferably 10-80% by mass, more preferably 30-75% by mass, and even more preferably 50-70% by mass, relative to the total amount (100% by mass) of the effective components of the polymerizable composition (x-1A). The total content of polyfunctional (meth)acrylate monomers in the polymerizable composition (x-1A) is preferably 0.5-15% by mass, more preferably 1-10% by mass, and even more preferably 2-5% by mass, relative to the total amount (100% by mass) of the effective components of the polymerizable composition (x-1A). The total content of the component (a1) in the polymerizable composition (x-1A) is preferably 15 to 90 mass %, more preferably 35 to 80 mass %, and even more preferably 55 to 75 mass %, relative to the total amount (100 mass %) of the effective ingredients in the polymerizable composition (x-1A).

(Prepolymer (a2) having energy-ray polymerizable functional groups) As the prepolymer (a2) having energy-ray polymerizable functional groups, there can be exemplified prepolymers having one energy-ray polymerizable functional group, prepolymers having two or more energy-ray polymerizable functional groups, etc. Among these, component (a2) preferably contains a prepolymer having two or more energy-ray polymerizable functional groups, more preferably a prepolymer having two energy-ray polymerizable functional groups, and still more preferably a prepolymer having two energy-ray polymerizable functional groups and having the energy-ray polymerizable functional groups at both ends, from the viewpoint of having excellent self-peeling properties and forming an adhesive layer with less contamination of the adherend after peeling.

As component (a2), a prepolymer containing two or more (meth)acrylic groups as energy-ray polymerizable functional groups (hereinafter, also referred to as "multifunctional (meth)acrylate prepolymer") is preferred. By containing the above-mentioned compound in component (a2), the cohesive force of the adhesive obtained by polymerizing the above-mentioned compound can be enhanced, and an adhesive layer (X1) having excellent self-peeling properties and less contamination of the adherend after peeling can be formed.

《Multifunctional (meth)acrylate prepolymer》 As a multifunctional (meth)acrylate prepolymer, there is no particular limitation as long as it is a prepolymer having two or more (meth)acryl groups in one molecule, and conventionally known ones can be appropriately used. The multifunctional (meth)acrylate prepolymer can be used alone or in combination of two or more.

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, and polyacrylic acrylate prepolymers.

Urethane acrylate prepolymers can be obtained, for example, by esterifying a polyurethane prepolymer with (meth)acrylic acid or a (meth)acrylic acid derivative. The polyurethane prepolymer is obtained by reacting a compound such as polyalkylene polyol, polyether polyol, polyester polyol, hydrogenated isoprene with a hydroxyl terminal, hydrogenated butadiene with a hydroxyl terminal, and polyisocyanate.

As the polyalkylene glycol used in the production of the urethane acrylate prepolymer, for example, polypropylene glycol, polyethylene glycol, polybutylene glycol, polyethylene glycol, etc., among which polypropylene glycol is preferred. In addition, when the functional group number of the obtained urethane acrylate prepolymer is set to 3 or more, for example, glycerin, trihydroxymethylpropane, triethanolamine, pentaerythritol, ethylenediamine, diethylenetriamine, sorbitol, sucrose, etc. can be appropriately combined.

Examples of polyisocyanates used in the production of urethane acrylate prepolymers include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylene diisocyanate; aromatic diisocyanates such as toluene diisocyanate, stilbene diisocyanate, and diphenyl diisocyanate; alicyclic diisocyanates such as dicyclohexylmethane diisocyanate and isophorone diisocyanate, etc. Among these, aliphatic diisocyanates are preferred, and hexamethylene diisocyanate is more preferred. In addition, the polyisocyanate is not limited to difunctional, and trifunctional or higher functional ones can also be used.

Examples of (meth)acrylic acid derivatives used in the preparation of urethane acrylate prepolymers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate; 2-isocyanate ethyl acrylate, 2-isocyanate ethyl methacrylate, 1,1-bis(acryloyloxymethyl)ethyl isocyanate, etc. Among these, 2-isocyanate ethyl acrylate is preferred.

As another method for producing the urethane acrylate prepolymer, there can be cited a method of reacting a hydroxyl group of a compound such as polyalkylene polyol, polyether polyol, polyester polyol, hydrogenated isoprene having a hydroxyl terminal, hydrogenated butadiene having a hydroxyl terminal, with a -N=C=O part of an isocyanate alkyl (meth) acrylate. In this case, as the isocyanate alkyl (meth) acrylate, for example, the above-mentioned 2-isocyanate ethyl acrylate, 2-isocyanate ethyl methacrylate, 1,1-bis (acryloyloxymethyl) ethyl isocyanate, etc. can be used.

The polyester acrylate prepolymer can be obtained, for example, by esterifying the hydroxyl group of a polyester prepolymer having hydroxyl groups at both ends obtained by condensation of a polycarboxylic acid and a polyol with (meth)acrylic acid. Alternatively, the polyester acrylate prepolymer can be obtained by esterifying the terminal hydroxyl group of a prepolymer obtained by adding an alkylene oxide to a polycarboxylic acid with (meth)acrylic acid.

Epoxyacrylate prepolymers can be obtained, for example, by esterifying (meth)acrylic acid with ethylene oxide rings of relatively low molecular weight bisphenol epoxy resins, novolac epoxy resins, etc. Alternatively, carboxyl-modified epoxyacrylate prepolymers obtained by partially modifying epoxyacrylate prepolymers with dibasic carboxylic anhydride can be used.

The polyether acrylate prepolymer can be obtained, for example, by esterifying the hydroxyl group of polyether polyol with (meth)acrylic acid.

The polyacrylic acid ester prepolymer may have an acryl group in the side chain, or may have an acryl group at both ends or at one end. The polyacrylic acid ester prepolymer having an acryl group in the side chain may be obtained, for example, by adding epoxypropyl methacrylate to the carboxyl group of polyacrylic acid. Furthermore, the polyacrylic acid ester prepolymer having an acryl group at both ends may be obtained, for example, by introducing an acryl group at both ends by utilizing the polymerization growth terminal structure of a polyacrylate prepolymer synthesized by the ATRP (Atom Transfer Radical Polymerization) method.

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

《Content of component (a2)》 The total content of the multifunctional (meth)acrylate prepolymer in the polymerizable composition (x-1A) is preferably 10-60% by mass, more preferably 15-55% by mass, and even more preferably 20-30% by mass, relative to the total amount (100% by mass) of the effective components of the polymerizable composition (x-1A). The total content of the component (a2) in the polymerizable composition (x-1A) is preferably 10-60% by mass, more preferably 15-55% by mass, and even more preferably 20-30% by mass, relative to the total amount (100% by mass) of the effective components of the polymerizable composition (x-1A).

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

Among the above-mentioned energy ray polymerizable components, the polymerizable composition (x-1A) preferably contains a polymerizable vinyl monomer, a multifunctional (meth)acrylate monomer, and a multifunctional (meth)acrylate prepolymer. The total content of the polymerizable vinyl monomer, the multifunctional (meth)acrylate monomer, and the multifunctional (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, further preferably 95% by mass or more, further preferably 99% by mass or more, and may also be 100% by mass, relative to the total amount of the energy ray polymerizable components (100% by mass).

The total content of the energy ray polymerizable components is preferably 70-98% by mass, more preferably 75-97% by mass, and further preferably 80-96% by mass, and further preferably 82-95% by mass, relative to the total amount of the active ingredients of the adhesive composition (x-1A) (100% by mass) or relative to the total amount of the adhesive layer (X1) (100% by mass). The total content of the energy ray polymerizable components can be interpreted as the content of the polymer formed by energy ray polymerization of the energy ray polymerizable components contained in the adhesive layer (X1).

(Thermal expansion particles) The suitable form of the thermal expansion particles contained in the polymerizable composition (x-1A) is the same as the suitable form of the thermal expansion particles described as the component contained in the above-mentioned adhesive layer (X1). The content of the thermal expansion particles relative to the total mass (100 mass%) of the above-mentioned adhesive layer (X1) can be interpreted as the content of the thermal expansion particles relative to the total mass (100 mass%) of the effective components of the polymerizable composition (x-1A).

(Photopolymerization initiator) The polymerizable composition (x-1A) preferably contains a photopolymerization initiator from the viewpoint of more efficiently polymerizing the energy ray polymerizable component. Examples of the photopolymerization initiator 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-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-oxolinyl-propane-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-dimethylaminobenzoate, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 2,4,6-trimethylbenzyl-diphenyl-phosphine oxide, etc. The photopolymerization initiator may be used alone or in combination of two or more.

When the polymerizable composition (x-1A) contains a photopolymerization initiator, its content is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass, and further preferably 0.3 to 1 part by mass relative to 100 parts by mass of the energy ray polymerizable component. If the content of the photopolymerization initiator is 0.1 parts by mass or more, the polymerization of the energy ray polymerizable component can be carried out more efficiently. On the other hand, if the content is 10 parts by mass or less, the photopolymerization initiator that remains unreacted can be eliminated or reduced, making it easier to adjust the obtained adhesive layer (X1) to the desired properties.

(Solvent) In addition, the polymerizable composition (x-1A) may contain a solvent such as a diluent within the scope that does not violate the purpose of the present invention, but it is better to contain no solvent. That is, the polymerizable composition (x-1A) is preferably a solvent-free polymerizable composition. When the polymerizable composition (x-1A) is a solvent-free polymerizable composition, when the adhesive layer (X1) is formed, the heat drying of the solvent can be omitted, so the expansion of the heat-expandable particles during the heat drying can be suppressed. In addition, when a solvent is used, as the volume decreases during drying, the heat-expandable particles tend to exist on one side, and the adhesion to the substrate (Y) or the adhesion of the adhesive surface becomes lower. On the other hand, the solvent-free polymerizable composition is unlikely to cause the above-mentioned problem because the thermally expandable particles are directly polymerized to form the adhesive layer (X1) in a state where they are uniformly dispersed in the energy-ray polymerizable component. When the polymerizable composition (x-1A) contains a solvent, the content thereof is preferably as small as possible, and is preferably 10% by mass or less, more preferably 1% by mass or less, further preferably 0.1% by mass or less, and further preferably 0.01% by mass or less relative to the total amount (100% by mass) of the effective components of the polymerizable composition (x-1A).

The polymerizable composition (x-1A) may contain other components in addition to the above components. Examples of other components include thickeners and adhesive additives described below.

(Manufacturing method of polymerizable composition (x-1A)) The polymerizable composition (x-1A) can be manufactured by mixing energy ray polymerizable components, thermally expandable particles, and other components as required. The obtained polymerizable composition (x-1A) is obtained by converting the energy ray polymerizable components into high molecular weight by subsequent energy ray polymerization. Therefore, when forming a layer, it can be adjusted to an appropriate viscosity compared with low molecular weight energy ray polymerizable components. Therefore, the polymerizable composition (x-1A) can be used directly as a coating solution for forming an adhesive layer (X1) without adding a solvent such as a diluent. Furthermore, although the adhesive layer (X1) formed by irradiating the polymerizable composition (x-1A) with energy rays contains a variety of polymers polymerized by energy ray polymerizable components and thermally expandable particles dispersed in the polymers, it is impossible or impractical to define these directly by structure and physical properties.

-Method of using adhesive composition (x-1B)- The method of using adhesive composition (x-1B) is a method of forming an adhesive layer (X1) by applying an adhesive composition (x-1B) containing an adhesive resin and thermally expandable particles. If this method is used, the adhesive resin contained in the adhesive layer (X1) becomes the adhesive resin itself contained in the adhesive composition (x-1B).

The adhesive composition (x-1B) contains an adhesive resin and thermally expandable particles. The following describes the components contained in the adhesive composition (x-1B).

The suitable embodiment of the heat-expandable particles contained in the adhesive composition (x-1B) is the same as the suitable embodiment of the heat-expandable particles described as the component contained in the above-mentioned adhesive layer (X1). The content of the heat-expandable particles relative to the total mass (100 mass%) of the above-mentioned adhesive layer (X1) can be interpreted as the content of the heat-expandable particles relative to the total mass (100 mass%) of the effective components of the adhesive composition (x-1B).

As the adhesive resin contained in the adhesive composition (x-1B), any polymer having a mass average molecular weight (Mw) of 10,000 or more is sufficient as long as the resin alone has adhesiveness. From the viewpoint of improving the adhesive force, the mass average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,500,000, and further preferably 30,000 to 1,000,000. As specific adhesive resins, for example, rubber resins such as acrylic resins, urethane resins, polyisobutylene resins, polyester resins, olefin resins, silicone resins, polyvinyl ether resins, etc. can be cited. Among these, the adhesive resin preferably contains an acrylic resin from the viewpoint of exhibiting excellent adhesive force and from the viewpoint that the expansion of the heat-expandable particles caused by the heat treatment easily forms unevenness on the surface of the formed adhesive layer. These adhesive resins can be used alone or in combination of two or more. In addition, when these adhesive resins are copolymers having two or more structural units, the morphology of the copolymer is not particularly limited, and it can be any of a block copolymer, a random copolymer, and a graft copolymer.

The content of the adhesive resin is preferably 30 to 99.99 mass %, more preferably 40 to 99.95 mass %, further preferably 50 to 99.90 mass %, further preferably 55 to 99.80 mass %, and even more preferably 60 to 99.50 mass %, relative to the total mass (100 mass %) of the active ingredients of the adhesive composition (X-1B) or the total mass (100 mass %) of the adhesive layer (X1).

The adhesive composition (x-1B) may contain other components in addition to the above components. Examples of other components include solvents, thickeners described below, and adhesive additives.

The adhesive composition (x-1B) can be produced by mixing an adhesive resin and other components as needed.

[Other components] The adhesive layer (X1) may contain other components other than the adhesive resin and the thermally expandable particles. As the above-mentioned other components, there can be cited thickeners, adhesive additives used in general adhesives other than the above-mentioned components, etc.

(Thickener) Thickener is a component used as needed to further enhance adhesion. In this manual, the so-called "thickener" refers to a substance with a mass average molecular weight (Mw) of less than 10,000, which is different from the adhesive resin. The mass average molecular weight (Mw) of the thickener is less than 10,000, preferably 400 to 9,000, more preferably 500 to 8,000, and even more preferably 800 to 5,000.

Examples of the tackifier include rosin-based resins, terpene-based resins, styrene-based resins, C5-based petroleum resins obtained by copolymerizing C5 distillates such as pentene, isoprene, piperine, and 1,3-pentadiene generated by thermal decomposition of petroleum naphtha, C9-based petroleum resins obtained by copolymerizing C9 distillates such as indene and vinyl toluene generated by thermal decomposition of petroleum naphtha, and hydrogenated resins obtained by hydrogenating these resins.

The softening point of the thickener is preferably 60-170°C, more preferably 65-160°C, and further preferably 70-150°C. In addition, in this specification, the "softening point" of the thickener means the value measured in accordance with JIS K 2531. A single thickener may be used, or two or more thickeners with different softening points, structures, etc. may be used in combination. When two or more thickeners are used, it is preferred that the weighted average softening point of the multiple thickeners is within the above range.

When the adhesive layer (X1) contains a tackifier, its content is preferably 0.01 to 65 mass %, more preferably 0.1 to 50 mass %, further preferably 1 to 40 mass %, and even more preferably 2 to 30 mass %, relative to the total mass (100 mass %) of the adhesive layer (X1).

(Additives for adhesives) As additives for adhesives, there are silane coupling agents, antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, delay agents, reaction accelerators (catalysts), ultraviolet absorbers, etc. These additives for adhesives can be used individually or in combination of two or more.

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

[Physical properties of adhesive layer (X1)] (Adhesion at 23°C before thermal expansion of adhesive layer (X1)) The adhesion at 23°C before thermal expansion of adhesive layer (X1) is preferably 0.1~12.0N/25mm, more preferably 0.5~9.0N/25mm, further preferably 1.0~8.0N/25mm, and further preferably 1.2~7.5N/25mm. If the adhesion at 23°C before thermal expansion of adhesive layer (X1) is 0.1N/25mm or more, it is more effective to suppress undesired peeling from the adherend during temporary fixing and positional displacement of the adherend. On the other hand, if the adhesive force is 12.0N/25mm or less, the peeling property during heat peeling can be further improved. In addition, in this specification, the adhesive force of the adhesive layer means the adhesive force to the mirror surface of the silicon mirror wafer. In addition, 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 embodiment.

(Adhesion at 23°C after thermal expansion of adhesive layer (X1)) The adhesion at 23°C after thermal expansion of the adhesive layer (X1) is preferably 1.5N/25mm or less, more preferably 0.05N/25mm or less, further preferably 0.01N/25mm or less, and further preferably 0N/25mm. In addition, the so-called adhesion of 0N/25mm means the adhesion below the measurement limit in the method for measuring adhesion at 23°C after thermal expansion described later, and also includes the situation where the adhesion is too small when the adhesive sheet is fixed for measurement and undesired peeling occurs. In this specification, the adhesive force at 23° C. after thermal expansion of the adhesive layer (X1) specifically means a value measured by the method described in the examples.

(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 to 5.0×10 ⁷ Pa, more preferably 5.0×10 ⁴ to 1.0×10 ⁷ Pa, and further preferably 1.0×10 ⁵ to 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, positional deviation 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, the expansion of the thermally expandable particles will easily form irregularities on the surface of the adhesive layer (X1), thereby tending to improve the peeling property during heat peeling. In addition, in this specification, the shear storage modulus G'(23) of the adhesive layer (X1) at 23°C refers to a value measured by the method described in the examples.

The adhesive layer (X1) is a layer containing thermally expandable particles, and the shear storage modulus G' of the adhesive layer (X1) may 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) (hereinafter, also referred to as "non-expandable adhesive layer (X1')") may be prepared without containing thermally expandable particles, and the shear storage modulus G' of the adhesive layer may be measured.

(Shear storage modulus G'(23) of the non-swelling adhesive layer (X1') at 23°C) The shear storage modulus G'(23) of the non-swelling adhesive layer (X1') at 23°C is preferably 1.0×10 ⁴ to 5.0×10 ⁷ Pa, more preferably 5.0×10 ⁴ to 1.0×10 ⁷ Pa, and further preferably 1.0×10 ⁵ to 5.0×10 ⁶ Pa. When the shear storage modulus G'(23) of the non-swelling adhesive layer (X1') is 1.0×10 ⁴ Pa or more, positional deviation 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, the surface of the adhesive layer (X1) tends to be more rugged due to the expansion of the thermally expandable particles, thereby improving the peeling property during heat peeling.

(Shear storage modulus G'(t) at the expansion starting temperature (t) of the non-expandable adhesive layer (X1')) The shear storage modulus G'(t) at the expansion starting temperature (t) of the aforementioned thermally expandable particles in the non-expandable adhesive layer (X1') is preferably 5.0×10 ³ ~1.0×10 ⁷ Pa, more preferably 1.0×10 ⁴ ~5.0×10 ⁶ Pa, further preferably 5.0×10 ⁴ ~1.0×10 ⁶ Pa. When the shear storage modulus G'(t) of the non-expandable adhesive layer (X1') is 5.0×10 ³ Pa or more, the positional deviation of the adherend during temporary fixing and the excessive sinking of the adherend into the adhesive layer (X1) can be suppressed, and at the same time, the curling of the adhesive sheet during heat peeling can be suppressed, and the workability tends to be improved. On the other hand, when the shear storage modulus G'(t) is 1.0×10 ⁷ Pa or less, it tends to be easy to form asperities on the surface of the adhesive layer (X1) due to the expansion of the thermally expandable particles, and the peeling property during heat peeling tends to be improved. In addition, in this specification, the shear storage modulus G' of the non-expandable adhesive layer (X1') at a specified temperature refers to a value measured by the method described in the embodiment.

(Thickness of 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 further preferably 20 to 80 μm. If the thickness of the adhesive layer (X1) at 23°C is 5 μm or more, it is easy to obtain sufficient adhesive force, and it tends to suppress undesired peeling from the adherend during temporary fixing and positional displacement of the adherend. On the other hand, if the thickness of the adhesive layer (X1) at 23°C is 150 μm or less, it tends to improve the peeling property during heat peeling, suppress the curling of the adhesive sheet during heat peeling, and improve the operability. In this specification, the thickness of the adhesive layer refers to the value measured by the method described in the embodiment. Also, the thickness of the adhesive layer (X1) refers to the value before the thermally expandable particles expand.

<Adhesive layer (X2)> The adhesive layer (X2) is an adhesive layer whose adhesive force is reduced by curing by irradiation with energy rays. The adhesive sheet used in one embodiment of the present invention is an adhesive layer to be attached to an object to be processed. By making the adhesive layer (X2) whose adhesive force is reduced by curing by irradiation with energy rays, when the object to be processed is peeled off from the adhesive sheet, the surface of the object to be processed is not contaminated by the thermally expandable particles and the expanded adhesive layer. Furthermore, by making the adhesive layer (X1) and the adhesive layer (X2) have different mechanisms for reducing the adhesive force of the adhesive layer, it is possible to prevent the adhesive force of the other adhesive layer from being undesirably reduced when the adhesive force of one adhesive layer is treated to reduce the adhesive force.

The adhesive layer (X2) is preferably a non-thermally expandable layer, and the volume change rate (%) of the adhesive layer (X2) calculated by the above formula is less than 5%, preferably less than 2%, more preferably less than 1%, further preferably less than 0.1%, and even more preferably less than 0.01%. Although it is preferred that the adhesive layer (X2) does not contain thermally expandable particles, it may contain thermally expandable particles within the scope that does not violate the purpose of the present invention. When the adhesive layer (X2) contains thermally expandable particles, the content thereof is as low as possible, and is preferably less than 3 mass%, more preferably less than 1 mass%, further preferably less than 0.1 mass%, further preferably less than 0.01 mass%, and further preferably less than 0.001 mass%, relative to the total mass (100 mass%) of the adhesive layer (X2).

The adhesive layer (X2) is preferably formed of an energy-ray-curable adhesive composition (x-2) (hereinafter, also simply referred to as "adhesive composition (x-2)"). By forming the adhesive layer (X2) from the adhesive composition (x-2), the adhesive layer (X2) can be made into an adhesive layer whose adhesive force is reduced by curing by energy-ray irradiation. The following describes the components contained in the adhesive composition (x-2).

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

[Non-energy ray-curable adhesive resin (I)] The mass average molecular weight (Mw) of the non-energy ray-curable adhesive resin (I) is preferably 250,000 to 1.5 million, more preferably 350,000 to 1.3 million, further preferably 450,000 to 1.1 million, and even more preferably 650,000 to 1.05 million.

Examples of non-energy ray-curable adhesive resins (I) include acrylic resins, rubber resins, silicone resins, etc. Among these, acrylic resins are preferred. The following describes acrylic resins in detail.

(Acrylic resin) As the acrylic resin, 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)") is preferred. The acrylic resin may be a homopolymer composed only of the structural unit (p1) derived from the above-mentioned monomer (p1), but a copolymer containing 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 monomer containing a functional group (hereinafter, also referred to as "monomer (p3)") together with the structural unit (p1) is preferred.

From the viewpoint of improving the adhesion of the adhesive layer (X2), the carbon number of the alkyl group of the monomer (p1) is preferably 4 to 20, more preferably 4 to 12, and even more preferably 4 to 6. The alkyl group of the monomer (p1) may be a linear chain or a branched chain.

Examples of the monomer (p1) include butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate. In addition, these monomers (p1) may be used alone or in combination of two or more. Among these, butyl (meth)acrylate is preferred from the viewpoint of improving the adhesion of the adhesive layer (X2).

The content of the structural unit (p1) relative to the total structural units of the acrylic resin when the acrylic resin is a copolymer is preferably 40 to 98 mass %, more preferably 45 to 95 mass %, and even more preferably 50 to 90 mass %.

Examples of the monomer (p2) include methyl (meth)acrylate, ethyl (meth)acrylate, and propyl (meth)acrylate. In addition, one of these monomers (p2) may be used alone, or two or more may be used in combination. Among these, methyl (meth)acrylate is preferred.

The content of the structural unit (p2) relative to the total structural units of the acrylic resin when the acrylic resin is a copolymer is preferably 1 to 30 mass %, more preferably 3 to 26 mass %, and even more preferably 6 to 22 mass %.

Monomer (p3) refers to a monomer that reacts with a crosslinking agent described below and has a functional group that can serve as a crosslinking starting point or a functional group that has a crosslinking promoting effect. Examples of the functional group possessed by monomer (p3) include hydroxyl, carboxyl, amino, and epoxy groups. Among these, carboxyl or hydroxyl groups are preferred from the perspective of reactivity with a crosslinking agent.

Examples of the monomer (p3) include hydroxyl-containing monomers, carboxyl-containing monomers, amino-containing monomers, and epoxy-containing monomers. These monomers (p3) may be used alone or in combination of two or more. Among these, hydroxyl-containing monomers and carboxyl-containing monomers are preferred, and hydroxyl-containing monomers are more preferred.

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, and the like; and unsaturated alcohols such as vinyl alcohol and allyl alcohol.

Examples of the carboxyl 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, citric acid and their anhydrides; and 2-carboxyethyl methacrylate.

The content of the structural unit (p3) relative to the total structural units of the acrylic resin when the acrylic resin is a copolymer is preferably 1 to 35 mass %, more preferably 3 to 32 mass %, and even more preferably 6 to 30 mass %.

In addition, the acrylic resin may also contain structural units derived from monomers copolymerizable with the acrylic monomers in addition to the above structural units (p1) to (p3). Examples of such monomers include styrene, α-methylstyrene, vinyltoluene, vinyl formate, vinyl acetate, acrylonitrile, and acrylamide.

[Energy ray-curable adhesive resin (II)] The adhesive resin (II) is an energy ray-curable adhesive resin having an unsaturated group introduced into the side chain of the above-mentioned non-energy ray-curable adhesive resin (I). The mass average molecular weight (Mw) of the energy ray-curable adhesive resin (II) having an unsaturated group introduced into the side chain is preferably 300,000 to 1.6 million, more preferably 400,000 to 1.4 million, further preferably 500,000 to 1.2 million, and even more preferably 700,000 to 1.1 million. As the main chain of the adhesive resin (II), although the above-mentioned adhesive resin (I) can be used, an acrylic resin is preferred, and an acrylic copolymer having structural units (p1), (p2) and (p3) is more preferred. As the unsaturated group in the side chain of the adhesive resin (II), examples include (meth)acryl, vinyl, allyl, etc., but (meth)acryl is preferred.

The synthesis method of the adhesive resin (II) includes, for example, a method in which a functional group-containing monomer is copolymerized to the adhesive resin (I) to provide a functional group, and a compound having both a substituent group and an unsaturated group that can bond to the functional group is added to allow the functional group of the copolymer to bond to the substituent group. As the functional group-containing monomer copolymerized to the adhesive resin (I), the compounds listed as the above-mentioned monomer (p3) can be cited. As the substituent group that bonds to the functional group, an isocyanate group, a glycidyl group, etc. can be cited. Therefore, examples of the compound having both a substituent capable of bonding to the functional group and an unsaturated group include (meth)acryloxyethyl isocyanate, (meth)acryl isocyanate, and glyoxypropyl (meth)acrylate.

[Crosslinking agent] The adhesive composition (x-2A) and (x-2B) preferably contain a crosslinking agent. The main purpose of adding the crosslinking agent is to react with the functional group of the non-energy ray-curable adhesive resin (I) or the energy ray-curable adhesive resin (II) in the side chain derived from the functional group of the monomer (p3) possessed by the above-mentioned acrylic resin, so as to crosslink the adhesive resins with each other.

Examples of the crosslinking agent include isocyanate crosslinking agents such as toluene diisocyanate, hexamethylene diisocyanate, and adducts thereof; epoxy crosslinking agents such as ethylene glycol epoxypropyl ether; hexa[1-(2-methyl)-aziridinyl]triphosphocyanate; Aziridine crosslinking agents such as aziridine; chelate crosslinking agents such as aluminum chelate; etc. These crosslinking agents can be used alone or in combination of two or more. Among these, isocyanate crosslinking agents are preferred from the perspective of increasing cohesion and adhesion, and from the perspective of ease of handling.

The amount of the crosslinking agent blended may be appropriately adjusted depending on the number of functional groups in the structures of the adhesive resins (I) and (II). However, from the viewpoint of promoting the crosslinking reaction, the amount is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 7 parts by mass, and even more preferably 0.05 to 4 parts by mass, relative to 100 parts by mass of the adhesive resins (I) and (II).

[Photopolymerization initiator] In addition, the adhesive composition (x-2A) and (x-2B) preferably contain a photopolymerization initiator. By containing a photopolymerization initiator, the curing reaction can be fully carried out even with relatively low energy rays such as ultraviolet rays. As the photopolymerization initiator, for example, 1-hydroxy-cyclohexyl-phenyl-ketone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzyl phenyl sulfide, tetramethylsulfonyl monosulfide, azobisisobutyronitrile, bibenzyl, diacetyl, 8-chloroanthraquinone, etc. can be cited. These photopolymerization initiators can be used alone or in combination of two or more. The amount of the photopolymerization initiator blended is preferably 0.01 to 10 parts by mass, more preferably 0.03 to 5 parts by mass, and even more preferably 0.05 to 2 parts by mass, relative to 100 parts by mass of the adhesive resins (I) and (II).

[Other additives] The adhesive compositions (x-2A) and (x-2B) may contain other additives within the range that does not impair the effects of the present invention. Other additives include the same thickeners and adhesive additives that may be contained in the adhesive layer (X1), and the appropriate configuration and content are also the same.

In addition, the adhesive compositions (x-2A) and (x-2B) can also be diluted with a solvent to form a solution from the viewpoint of improving the coating properties on the substrate, the release sheet, etc. Examples of the solvent include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dihydrofuran, In addition, these solvents can be directly used as solvents used in the production of adhesive resins (I) and (II), and in order to make the solution of the adhesive composition evenly spread, one or more solvents other than the solvents used in the preparation can be added.

When the adhesive compositions (x-2A) and (x-2B) are diluted with a solvent, the solid content concentration is preferably 5 to 60% by mass, more preferably 10 to 45% by mass, and further preferably 15 to 30% by mass.

The adhesive composition (x-2) can be produced by mixing an adhesive resin, a crosslinking agent, a photopolymerization initiator, and other additives as required.

[Physical properties of adhesive layer (X2)] (Adhesion of adhesive layer (X2)) The adhesion of the adhesive surface of the adhesive layer (X2) before energy ray irradiation is preferably 4.0~30.0N/25mm, more preferably 6.0~27.0N/25mm, further preferably 8.0~24.0N/25mm, and further preferably 10.0~20.0N/25mm. If the adhesion of the adhesive surface of the adhesive layer (X2) before energy ray irradiation is 4.0N/25mm or more, it is more effective to suppress undesired peeling from the adherend during temporary fixing, positional deviation of the adherend, etc. On the other hand, if the adhesive force is less than 30.0N/25mm, the adhesive force after energy ray irradiation can be suppressed. The adhesive force after energy ray irradiation in the adhesive surface of the adhesive layer (X2) is preferably 0.01~2.0N/25mm, more preferably 0.02~1.0N/25mm, further preferably 0.03~0.50N/25mm, and further preferably 0.05~0.30N/25mm. If the adhesive force after energy ray irradiation in the adhesive surface of the adhesive layer (X2) is 0.01N/25mm or more, it can effectively suppress the undesired falling off of the processing object in the step. On the other hand, if the adhesive force is 2.0 N/25 mm or less, it becomes easy to peel off without causing damage to the adherend.

(Shear storage modulus G'(23) of the adhesive layer (X2) at 23°C) The shear storage modulus G'(23) of the adhesive layer (X2) at 23°C is preferably 5.0×10 ³ to 1.0×10 ⁷ Pa, more preferably 1.0×10 ⁴ to 5.0×10 ⁶ Pa, and further preferably 5.0×10 ⁴ to 1.0×10 ⁶ Pa. When the shear storage modulus G'(23) of the adhesive layer (X2) is 5.0×10 ³ Pa or more, there is a tendency to suppress positional deviation of the adherend during temporary fixing and excessive sinking of the adherend into the adhesive layer (X2). On the other hand, if the shear storage modulus G'(23) is 1.0×10 ⁷ Pa or less, the adhesion to the adherend tends to be improved. In the present specification, the shear storage modulus G'(23) at 23°C of the adhesive layer (X2) can be measured by the same method as the shear storage modulus G' at 23°C of the adhesive layer (X1).

(Thickness of adhesive layer (X2) at 23°C) The thickness of the adhesive layer (X2) at 23°C is preferably 5 to 150 μm, more preferably 8 to 100 μm, further preferably 12 to 70 μm, and further preferably 15 to 50 μm. If the thickness of the adhesive layer (X2) at 23°C is 5 μm or more, it is easy to obtain sufficient adhesion, and it tends to suppress undesired peeling from the adherend during temporary fixing, positional deviation of the adherend, etc. On the other hand, if the thickness of the adhesive layer (X2) at 23°C is 150 μm or less, it tends to be easy to handle the adhesive sheet.

<Peeling material> As peeling materials, peeling sheets with double-sided peeling treatment, peeling sheets with single-sided peeling treatment, etc. are used. For example, peeling materials obtained by coating a peeling agent on a base material for peeling materials. As base materials for peeling materials, for example, plastic films, papers, etc. are exemplified. As plastic films, polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, etc.; olefin resin films such as polypropylene resin, polyethylene resin, etc. are exemplified. As paper, for example, high-quality paper, translucent paper (glassine paper), kraft paper, etc. are exemplified.

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

The thickness of the peeling material is preferably 10-200 μm, more preferably 20-150 μm, and further preferably 35-80 μm.

<Method for producing adhesive sheet> The method for producing the adhesive sheet used in one embodiment of the present invention is preferably a method that appropriately selects the type of material suitable for use. Although the following describes a method for producing an adhesive sheet in which the adhesive layer (X1) is formed using the above-mentioned polymerizable composition (x-1A) or adhesive composition (x-1B), the method for producing the adhesive sheet used in one embodiment of the present invention is not limited to such methods.

-Method using polymerizable composition (x-1A)- In the case where the polymerizable composition (x-1A) is used in the formation of the adhesive layer (X1), the adhesive sheet used in one embodiment of the present invention is preferably manufactured by a method comprising the step of irradiating the polymerizable composition (x-1A) with energy rays to form a polymer of the energy ray polymerizable component. More specifically, it is preferred to include the following steps IA to IIIA. Step IA: A step of forming a polymerizable composition layer composed of a polymerizable composition (x-1A) on one side of the substrate (Y) Step IIA: A step of forming a polymer of the energy ray polymerizable component by irradiating the aforementioned polymerizable composition layer with energy rays, and forming an adhesive layer (X1) containing the polymer and the aforementioned thermal expansion particles Step IIIA: A step of forming an adhesive layer (X2) on the other side of the substrate (Y) Steps IA to IIIA are described below.

[Step IA] Step IA is not particularly limited as long as it is a step of forming a polymerizable composition layer on one side of the substrate (Y), but preferably includes the following steps IA-1 to IA-3. Step IA-1: A step of coating a polymerizable composition (x-1A) on the peeling treatment surface of the peeling material to form a polymerizable composition layer Step IA-2: A step of irradiating the above-mentioned polymerizable composition layer with a first energy ray to pre-polymerize the energy ray polymerizable components in the polymerizable composition layer Step IA-3: A step of attaching the polymerizable composition layer after the first energy ray irradiation to the substrate (Y)

(Step IA-1) Step IA-1 is a step of coating a polymerizable composition (x-1A) on the peeling treatment surface of the peeling material to form a polymerizable composition layer. In step IA-1, as a method for coating the polymerizable composition (x-1A) on the peeling material, for example, a rotary coating method, a spray coating method, a rod coating method, a knife coating method, a roller coating method, a doctor blade coating method, a mold coating method, a gravure coating method, etc. can be cited.

As described above, the polymerizable composition (x-1A) is preferably a solvent-free polymerizable composition. When the polymerizable composition (x-1A) is a solvent-free polymerizable composition, the step of heating and drying the solvent in this step may not be performed. On the other hand, when the polymerizable composition (x-1A) contains a solvent within the scope that does not violate the purpose of the present invention, after applying the polymerizable composition (x-1A), heating and drying may also be performed, but the heating temperature in this case is determined to be less than the expansion start temperature (t) of the thermally expandable particles.

(Step IA-2) Step IA-2 is a step of irradiating the polymerizable composition layer formed in step IA-1 with a first energy ray to prepolymerize the energy ray polymerizable components in the polymerizable composition layer. The first energy ray irradiation is performed for the purpose of increasing the viscosity of the polymerizable composition by prepolymerizing the energy ray polymerizable components, thereby improving the shape retention of the polymerizable composition layer. During the first energy ray irradiation, the energy ray polymerizable components are not completely polymerized but remain in the prepolymerization stage. This can improve the adhesion between the polymerizable composition layer in step IA-3 and the substrate (Y).

As the energy ray used for the first energy ray irradiation in step IA-2, ultraviolet rays are preferred because they are easy to handle among the above. The illuminance of the ultraviolet rays in the first energy ray irradiation is preferably 70 to 250 mW/cm ² , more preferably 100 to 200 mW/cm ² , and further preferably 130 to 170 mW/cm ² . Furthermore, the amount of ultraviolet rays in the first energy ray irradiation is preferably 40 to 200 mJ/cm ² , more preferably 60 to 150 mJ/cm ² , and further preferably 80 to 120 mJ/cm ² . The first energy ray irradiation may be performed once or in multiple times. Furthermore, in order to suppress the temperature rise of the polymerizable composition layer due to polymerization heat, etc., it may be performed while cooling the polymerizable composition layer.

(Step IA-3) Step IA-3 is a step of attaching the polymerizable composition layer to the substrate (Y) after the first energy ray irradiation. The method of attaching the substrate (Y) to the polymerizable composition layer is not particularly limited, and an example thereof is a method of laminating the substrate (Y) to the exposed surface of the polymerizable composition layer. Lamination can be performed while heating or without heating, but from the perspective of suppressing the expansion of thermally expandable particles, it is better to perform it 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.

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

Here, when the first energy ray irradiation is performed in step IA, the energy ray irradiation in step IIA becomes the second energy ray irradiation performed on the pre-polymerized polymerizable composition layer. Unlike the first energy ray irradiation, the energy ray irradiation in step IIA is preferably performed to the extent that even if the energy ray is further irradiated, the polymerization of the energy ray polymerizable component does not substantially proceed. By the energy ray irradiation in step IIA, the energy ray polymerizable component is polymerized to form a polymer of the energy ray polymerizable component constituting the adhesive layer (X1).

As the energy ray used in the energy ray irradiation of step IIA, ultraviolet rays are preferred because they are easy to handle among the above. The illuminance of the ultraviolet rays in the energy ray irradiation of step IIA is preferably 100-350 mW/cm ² , more preferably 150-300 mW/cm ² , and further preferably 180-250 mW/cm ² . The amount of ultraviolet rays in the energy ray irradiation of step IIA is preferably 500-4,000 mJ/cm ² , more preferably 1,000-3,000 mJ/cm ² , and further preferably 1,500-2,500 mJ/cm ² . The energy ray irradiation of step IIA may be performed once or in multiple times. Furthermore, in order to suppress the temperature rise of the polymerizable composition layer due to the heat of polymerization, the polymerizable composition layer may be cooled.

In addition, when step IA includes the above steps IA-1 to IA-3, the polymerizable composition layer is obtained as an intermediate layer of a laminated body laminated in the order of a peeling material, a polymerizable composition layer, and a substrate (Y). At this time, the second energy ray irradiation can also be performed on the laminated body having such a structure. In this case, from the perspective of making it possible to irradiate the polymerizable composition layer existing as an intermediate layer of the laminated body with sufficient energy rays, it is preferred that at least one of the peeling material and the substrate (Y) is selected to have energy ray transmittance.

From the viewpoint of suppressing the expansion of the heat-expandable particles in any of the steps IA and IIA, it is preferable not to heat the polymerizable composition. In addition, the "heating" mentioned here means the desired heating during drying, lamination, etc., and does not include the temperature rise caused by the heat given to the polymerizable composition by energy ray irradiation, the polymerization heat generated by the polymerization of the energy ray polymerizable composition, etc. The heating temperature in the step of heating the polymerizable composition as needed is preferably "a temperature lower than the expansion start temperature (t)", more preferably "expansion start temperature (t) - 5°C" or lower, further preferably "expansion start temperature (t) - 10°C" or lower, and further preferably "expansion start temperature (t) - 15°C" or lower. In addition, when the temperature of the polymerizable composition rises undesirably, the temperature of the polymerizable composition is preferably cooled to the above temperature range.

[Step IIIA] Step IIIA is a step of forming an adhesive layer (X2) on the other 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) on one side of the peeling 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 side of the substrate (Y)

In step IIIA-1, as a method for applying the adhesive composition (x-2), the same method as the method cited as a method for applying the polymerizable composition (x-1A) in step IA-1 can be cited. In addition, when the adhesive layer (X2) contains a solvent, it can also include a step of drying the coating film after applying the adhesive composition (x-2). In addition, as mentioned above, the peeling material used in step IIIA-1 and the peeling material used in step IA-1 are preferably designed to have different peeling forces from the viewpoint of suppressing the phenomenon that the adhesive layer is peeled off as the two peeling materials are divided.

In step IIIA-2, as a method for attaching the adhesive layer (X2) to the substrate (Y), the same method as the method for attaching the substrate (Y) to the polymerizable composition layer in step IA-3 can be cited, and the preferred embodiment is also the same.

-Method using adhesive composition (x-1B)- In the case where the above-mentioned adhesive composition (x-1B) is used in the formation of the adhesive layer (X1), the adhesive sheet used in one embodiment of the present invention can be manufactured by a method comprising the following steps IB to IIIB, for example. ・Step IB: On the peeling treatment surface of the peeling material, an adhesive composition (x-1B) is applied to form a coating film, and the coating film is dried to form an adhesive layer (X1) ・Step IIB: On the peeling treatment surface of another peeling material, an adhesive layer forming material, i.e., an adhesive composition (x-2), is applied to form a coating film, and the coating film is dried to form an adhesive layer (X2) ・Step III B: A step of laminating the adhesive layer (X1) formed in step IB on one surface of the substrate, and laminating the adhesive layer (X2) formed in step IIB on the other surface of the substrate. The method and suitable conditions for coating, drying and laminating the adhesive composition in each step are the same as the method and suitable conditions described in the method using the polymerizable composition (x-1A).

[Steps of the method for manufacturing a semiconductor device] Next, the steps of 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 addition, although the following description mainly describes an example of using a semiconductor wafer as a processing object, the same is true for other processing objects.

<Step 1> Step 1 is a step of attaching the object to be processed to the adhesive layer (X2) of the adhesive sheet and attaching the support body to the adhesive layer (X1). FIG. 2 shows a cross-sectional view of the step of attaching the semiconductor wafer W to the adhesive layer (X2) of the adhesive sheet 1a and attaching the support body 2 to the adhesive layer (X1). The semiconductor wafer W is attached with the surface W1, which is the electrical path surface, being the adhesive layer (X2). The semiconductor wafer W may be a silicon wafer, or a wafer of gallium arsenide, silicon carbide, sapphire, lithium tantalum, 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 may be formed by conventional methods such as etching and stripping.

The material of the support body 2 can be appropriately selected according to the type of the object to be processed, the processing content, etc., and the required characteristics such as mechanical strength and heat resistance. As the material of the support body 2, metal materials such as SUS, non-metallic inorganic materials such as glass and silicon wafers, resin materials such as epoxy resin, ABS resin, acrylic resin, engineering plastics, super engineering plastics, polyimide resin, polyamide imide resin, etc., and composite materials such as glass epoxy resin, etc. Among them, SUS, glass, and silicon wafers are preferred. As the above-mentioned engineering plastics, nylon, polycarbonate (PC), polyethylene terephthalate (PET), etc. can be cited. Examples of the super engineering plastics include polyphenylene sulfide (PPS), polyether sulfide (PES), and polyether ether ketone (PEEK).

The support body 2 is preferably attached to the entire adhesive surface of the adhesive layer (X1). Therefore, the surface area of the support body 2 attached to the adhesive surface of the adhesive layer (X1) is preferably greater than the area of the adhesive surface of the adhesive layer (X1). In addition, the surface of the support body 2 attached to the adhesive surface of the adhesive layer (X1) is preferably flat. The shape of the support body 2 is not particularly limited, but it is preferably in the form of a plate. The thickness of the support body 2 can be appropriately selected in consideration of the required characteristics, but is preferably greater than 20μm and less than 50mm, and more preferably greater than 60μm and less than 20mm.

<Step 2> Step 2 is a step of performing one or more processing selected from grinding and individualization on the aforementioned processing object. As one or more processing selected from grinding and individualization, grinding using a grinder, etc., individualization by blade cutting, laser cutting, invisible cutting (registered trademark) method, blade pre-cutting method, invisible pre-cutting method, etc. can be cited. Among these, individualization processing by invisible cutting method, grinding processing and individualization processing by blade pre-cutting method, grinding processing and individualization processing by invisible pre-cutting method are suitable, and grinding processing and individualization processing by blade pre-cutting method, grinding processing and individualization processing by invisible pre-cutting method are more suitable.

Invisible dicing is a method of forming a modified area inside a semiconductor wafer by irradiating laser light, and using the modified area as a starting point for segmentation to separate the semiconductor wafer. The modified area formed in the semiconductor wafer is a portion that has become brittle due to multi-photon absorption. Due to the expansion of the semiconductor wafer, stress is applied in a direction parallel to the wafer surface and in the direction of wafer expansion. The modified area is used as a starting point to crack and extend toward the surface and back of the semiconductor wafer, thereby individualizing into semiconductor chips. That is, the modified area is formed along the segmentation line during segmentation. The modified area is formed inside the semiconductor wafer by irradiating the inside of the semiconductor wafer with laser light focused on it. The incident surface of the laser light can be the surface or the back of the semiconductor wafer. Furthermore, the laser light incident surface may be a surface to which the adhesive sheet is attached. In this case, the laser light is irradiated onto the semiconductor wafer through the adhesive sheet.

The blade pre-cutting method is also called the DBG method (Dicing Before Grinding). The blade pre-cutting method is a method in which a groove is formed in advance with a depth shallower than the thickness of the semiconductor wafer along the predetermined dividing line, and then the back of the semiconductor wafer is ground to thin it until the grinding surface at least reaches the groove and is sliced at the same time. The groove reached by the grinding surface becomes a cut that passes through the semiconductor wafer, and the semiconductor wafer is divided and sliced into semiconductor chips through the cut. The pre-formed groove is usually provided on the surface (conductor surface) of the semiconductor wafer, for example, it can be formed by cutting using a conventionally known wafer cutting device equipped with a cutting blade.

Stealth Dicing Before Grinding (SDBG) is also called Stealth Dicing Before Grinding (SDBG). The stealth pre-cutting method is the same as the stealth cutting method. It forms a modified area inside the semiconductor wafer by irradiating laser light, and uses the modified area as the starting point for segmentation to separate the semiconductor wafer. However, the point that the semiconductor wafer is thinned by grinding and the semiconductor wafer is separated into semiconductor chips is different from the stealth cutting method. Specifically, the back of the semiconductor wafer with the modified area is ground to make it thinner. At the same time, the pressure applied to the semiconductor wafer is used to extend the crack from the modified area as the starting point to the bonding surface of the adhesive layer of the semiconductor wafer, and the semiconductor wafer is separated into semiconductor chips. In addition, the grinding thickness after forming the modified area can be the thickness of the modified area, but even if it is not strictly ground to the modified area, it is also possible to cut it to a position close to the modified area and cut it with a processing pressure such as a grinding stone. In the SDBG process, the semiconductor chips that have been individualized are in contact with each other, which easily causes the so-called chipping phenomenon in which the outer edge is finely damaged due to vibration. Therefore, the manufacturing method of a semiconductor device of one aspect of the present invention that can suppress vibration by firmly fixing the support body is particularly suitable for the SDBG method.

When the semiconductor wafer W is sliced by the blade pre-cutting method, it is preferable to pre-form a groove on the surface W1 of the semiconductor wafer W attached to the adhesive layer (X2) in step 1. On the other hand, when the semiconductor wafer W is sliced by the invisible pre-cutting method, the semiconductor wafer W attached to the adhesive layer (X2) in step 1 can be irradiated with laser light to pre-form a modified area, and the semiconductor wafer W attached to the adhesive layer (X2) can also be irradiated with laser light to form a modified area.

FIG3 shows a cross-sectional view of the step of forming a plurality of modified regions 4 using a laser light irradiation device 3 on a semiconductor wafer W attached to an adhesive layer (X2). The laser light is irradiated from the back side W2 of the semiconductor wafer W to form a plurality of modified regions 4 at approximately equal intervals inside the semiconductor wafer W.

FIG4 shows a cross-sectional view of a step of grinding the back side W2 of a semiconductor wafer W having a modified region 4 by a grinder 5, and thinning the semiconductor wafer W by cutting starting from the modified region 4 and simultaneously individualizing the semiconductor wafer W into a plurality of semiconductor chips CP. The back side W2 of the semiconductor wafer W having a modified region 4 is ground while the support body 2 supporting the semiconductor wafer W is fixed on a fixed table such as a chuck table.

The thickness of the semiconductor chip CP after grinding is preferably 5 to 100 μm, more preferably 10 to 45 μm. Furthermore, when grinding and individualizing are performed by invisible pre-cutting method, the thickness of the semiconductor chip CP obtained by grinding is easily set to 50 μm or less, and more preferably 10 to 45 μm. The size of the semiconductor chip CP after grinding in a plane view is preferably less than 600 mm ² , more preferably less than 400 mm ² , and further preferably less than 300 mm ^2. In addition, the so-called plane view refers to the thickness direction. The shape of the semiconductor chip CP after individualizing in a plane view can be square or a long and thin shape such as a rectangle.

<Step 3> Step 3 is 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 aforementioned processing. FIG. 5 shows a cross-sectional view of the step of attaching a thermosetting film 6 having a support sheet 7 to the surface of a plurality of semiconductor chips CP that are obtained by the aforementioned processing that is opposite to the adhesive layer (X2).

The thermosetting film 6 is a thermosetting film obtained by forming a resin composition containing at least a thermosetting resin, and is used as an adhesive when mounting the semiconductor chip CP on a substrate. The thermosetting film 6 may also contain a curing agent for the above-mentioned thermosetting resin, a thermoplastic resin, an inorganic filler, a curing accelerator, etc. as needed. As the thermosetting film 6, a thermosetting film generally used as a die bonding film, a chip bonding film, etc. can be used. Although the thickness of the thermosetting film 6 is not particularly limited, it is usually 1~200μm, preferably 3~100μm, and more preferably 5~50μm. The support sheet 7 may be any material as long as it can support the thermosetting film 6, and examples thereof include resins, metals, and paper materials listed as the base material (Y) of the adhesive sheet used in one embodiment of the present invention.

As a method of attaching the thermosetting film 6 to a plurality of semiconductor chips CP, for example, a method by lamination can be cited. Lamination can be performed while heating or without heating. The heating temperature when laminating while heating is preferably "a temperature lower than the expansion start temperature (t)" from the viewpoint of suppressing the expansion of the thermally expansive particles and suppressing the thermal change of the adherend, and is more preferably "the expansion start temperature (t) -5°C" or less, further preferably "the expansion start temperature (t) -10°C" or less, and even more preferably "the expansion start temperature (t) -15°C" or less.

<Step 4> Step 4 is a step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion start temperature (t) to separate the adhesive layer (X1) from the aforementioned support body. FIG. 6 shows a cross-sectional view illustrating the step of heating the adhesive sheet 1a to separate the adhesive layer (X1) from the support body 2.

The heating temperature in step 4 is above the expansion start temperature (t) of the heat-expandable particles, preferably "a temperature higher than the expansion start temperature (t)", more preferably "expansion start temperature (t) + 2°C" or above, further preferably "expansion start temperature (t) + 4°C" or above, and further preferably "expansion start temperature (t) + 5°C" or above. In addition, from the perspective of energy saving and suppressing the thermal changes of the adherend during heat peeling, the heating temperature in step 4 is preferably below "expansion start temperature (t) + 50°C", more preferably below "expansion start temperature (t) + 40°C", and further preferably below "expansion start temperature (t) + 20°C". The heating temperature in step 4 is preferably 120°C or lower, more preferably 115°C or lower, further preferably 110°C or lower, and further preferably 105°C or lower, within the range above the expansion start temperature (t) from the viewpoint of suppressing thermal changes of the adherend.

<Step 5> Step 5 is a step of irradiating the adhesive layer (X2) with energy rays to separate the adhesive layer (X2) from the aforementioned processing object. FIG. 7 shows a cross-sectional view illustrating the step of separating the adhesive layer (X2) from a plurality of semiconductor chips CP. The adhesive layer (X2) is hardened by irradiation with energy rays, and the adhesive force is reduced. By irradiation with energy rays, the processing object and the adhesive layer (X2) can be easily separated. As the energy ray used for the energy ray irradiation in step 5, ultraviolet rays are preferably used because they are easy to handle among the above-mentioned ones. The illuminance and amount of ultraviolet light may be sufficiently low as long as the adhesive layer (X2) and the object to be processed are adhered to each other. For example, the illuminance of ultraviolet light is preferably 100-400 mW/cm ² , more preferably 150-350 mW/cm ² , and further preferably 180-300 mW/cm ^{2 .} The amount of ultraviolet light is preferably 100-2,000 mJ/cm ² , more preferably 200-1,000 mJ/cm ² , and further preferably 300-500 mJ/cm ² . Although the energy rays can be irradiated from any direction as long as the adhesive layer (X2) can be cured, it is preferred to irradiate from the adhesive layer (X1) side from the viewpoint of efficiently curing it. At this time, from the viewpoint of allowing the adhesive layer (X2) to be fully irradiated with the energy rays, the substrate (Y) and the adhesive layer (X1) are preferably those that have energy ray permeability.

After the above steps 1 to 5, a plurality of semiconductor chips CP attached to the thermosetting film 6 can be obtained. Then, the thermosetting film 6 attached to the plurality of semiconductor chips CP is divided into the same shape as the semiconductor chip CP to obtain a semiconductor chip CP attached with the thermosetting film 6. As a method for dividing the thermosetting film 6, for example, laser cutting, expansion, dissolution, etc. using laser light can be applied. FIG. 8 shows a semiconductor chip CP attached with the thermosetting film 6 divided into the same shape as the semiconductor chip CP.

The semiconductor chip CP with the thermosetting film 6 is then attached (chip bonding) to the substrate from the thermosetting film 6 side after appropriately performing an expansion step of expanding the interval between the semiconductor chips CP, a rearrangement step of arranging a plurality of semiconductor chips CP with the expanded interval, a reversal step of reversing the front and back of the plurality of semiconductor chips CP, etc. as needed. Thereafter, the semiconductor chip and the substrate can be fixed by thermally curing the thermosetting film 6. [Example]

Although the present invention is specifically described by the following examples, the present invention is not limited to the following examples. In addition, the "non-expandable adhesive layer (X1')" in the following description means an adhesive layer that does not contain thermally expandable particles. The adhesive layer that does not contain thermally expandable particles produced for the measurement of the shear storage modulus G' belongs to the non-expandable adhesive layer (X1'). The physical property values in the following examples are values measured by the following method.

[Mass average molecular weight (Mw)] Measured using a gel permeation chromatograph (manufactured by Tosoh Co., Ltd., product name "HLC-8020") under the following conditions, and the measured value is converted to standard polystyrene. (Measurement conditions) ・Column: "TSK guard column HXL-L", "TSK gel G2500HXL", "TSK gel G2000HXL", "TSK gel G1000HXL" (all manufactured by Tosoh Co., Ltd.) connected in sequence ・Column temperature: 40℃ ・Developing solvent: tetrahydrofuran ・Flow rate: 1.0mL/min

[Thickness of each layer] Measured using a constant pressure thickness tester manufactured by TECLOCK Co., Ltd. (model: "PG-02J", in accordance with standard specifications: JIS K6783, Z1702, Z1709).

[Average particle size (D ₅₀ ) and 90% particle size (D ₉₀ ) of thermally expansive particles] The particle distribution of thermally expansive particles before expansion at 23°C is measured using a laser diffraction particle size distribution measuring device (e.g., manufactured by Malvern, product name “Mastersizer 3000”). Then, the particle sizes corresponding to the 50% and 90% cumulative volume frequencies calculated from the smaller particle size in the particle distribution are defined as the “average particle size (D ₅₀ ) of thermally expansive particles” and the “90% particle size (D ₉₀ ) of thermally expansive particles”, respectively.

[Storage modulus E’ of substrate (Y)] The substrate (Y) cut into 5mm in length and 30mm in width was used as the test sample. The dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name “DMAQ800”) was used to measure the storage modulus E’ at the specified temperature under the conditions of test start temperature 0℃, test end temperature 200℃, heating rate 3℃/min, vibration frequency 1Hz, and amplitude 20μm.

[Shear storage modulus G'(23) of adhesive layer (X1) at 23°C] The adhesive layer (X1) was made into a sample with a diameter of 8mm and a thickness of 3mm as a test sample. The shear storage modulus G'(23) at 23°C was measured by the torsional shear method using a viscoelasticity measuring device (manufactured by Anton Paar, device name "MCR300") with a test start temperature of 0°C, a test end temperature of 300°C, a heating rate of 3°C/min, and a vibration rate of 1Hz.

[Shear storage modulus G’ of non-expandable adhesive layer (X1’)] In order to measure the shear storage modulus G’ excluding the influence of thermally expansive particles, a non-expandable adhesive layer (X1’) having the same structure as the adhesive layer (X1) in each manufacturing example except that the thermally expansive particles are not contained was prepared as a sample for measuring the shear storage modulus of the adhesive layer (X1) corresponding to each manufacturing example, and its shear storage modulus G’ was measured. The non-expandable adhesive layer (X1') was made into a diameter of 8mm x thickness of 3mm as a test sample. The viscoelasticity measuring device (made by Anton Paar, device name "MCR300") was used to measure the shear storage modulus G'(23) at 23℃ and the shear storage modulus G'(t) at the expansion start temperature (t) of the thermally expansive particles by the torsional shear method under the conditions of test start temperature 0℃, test end temperature 300℃, temperature rise rate 3℃/min, and vibration frequency 1Hz. The expansion start temperature (t) of the heat-expandable particles in the non-expandable adhesive layer (X1') which is the sample for measuring the shear storage modulus means the expansion start temperature (t) of the heat-expandable particles contained in the adhesive layer (X1) of the manufacturing example corresponding to the sample for measuring the shear storage modulus, and in this manufacturing example, it means 88°C as described later.

Synthesis Example 1 (Synthesis of Urethane Acrylate Prepolymer) 100 parts by mass of polypropylene glycol having a mass average molecular weight (Mw) of 3,000 (solid content conversion value; the same below), 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 reactant. The IR spectrum of the obtained reactant was measured by infrared spectroscopy, and it was confirmed that the isocyanate group almost disappeared. Thereafter, 1 part by mass of 2-isocyanate ethyl acrylate was mixed with the total amount of the obtained reactant, and stirred at 80°C for 3 hours to obtain a urethane acrylate prepolymer. The IR spectrum of the obtained urethane acrylate prepolymer was measured by infrared spectroscopy, and it was confirmed that the isocyanate group almost disappeared. The mass average molecular weight (Mw) of the obtained urethane acrylate prepolymer was 25,000.

[Manufacturing of Adhesive Sheet] Manufacturing Examples 1 to 3 (Manufacturing of Polymerizable Composition) Each component listed in Table 1 was mixed in the blending composition listed in Table 1 to obtain a solvent-free polymerizable composition. In addition, the details of each component listed in Table 1 are as follows. [Polymerizable vinyl monomer] 2EHA: 2-ethylhexyl acrylate (component (a1-1)) IBXA: isoborneol acrylate (component (a1-2)) HEA: 2-hydroxyethyl acrylate (component (a1-3)) 4HBA: 4-hydroxybutyl acrylate (component (a1-3)) [Multifunctional (meth)acrylate monomer] Trifunctional monomer: isocyanurate ethylene oxide modified triacrylate (component (a1-4)) [Multifunctional (meth)acrylate prepolymer] Urethane acrylate prepolymer: prepared in Synthesis Example 1 (component (a2)) Polyacrylic acrylate prepolymer: "KANEKA XMAP (Registered trademark) RC100C" (manufactured by Kaneka Co., Ltd., polyacrylic acid prepolymer having acryloyl groups at both ends, mass average molecular weight (Mw): 21,500) ((a2) component) [Photopolymerization initiator] 1-Hydroxycyclohexyl phenyl ketone [Thermal expansion particles] manufactured by AkzoNobel, product name "Expancel (Registered trademark) 031-40" (DU type), expansion start temperature (t) = 88°C, average particle size (D ₅₀ ) = 12.6μm, 90% particle size (D ₉₀ ) = 26.2μm In addition, "-" in "Composition of adhesive layer (X1) or non-expandable adhesive layer (X1')" in Table 1 means that the component is not mixed.

(Preparation of Adhesive Sheet) The solvent-free polymerizable composition prepared above was used to prepare an adhesive sheet in the following procedure. The solvent-free polymerizable composition was applied on the release-treated surface of a polyethylene terephthalate (PET) release film (manufactured by LINTEC Co., Ltd., product name "SP-PET382150", thickness: 38μm) to form a polymerizable composition layer. The polymerizable composition layer was irradiated with ultraviolet light at an illumination of 150 mW/ ^cm2 and a light quantity of 100 mJ/ ^cm2 for pre-polymerization. In addition, the thickness of the polymerizable composition layer was adjusted so that the thickness of the obtained adhesive layer (X1) became the thickness described in Table 2. Next, a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., COSMOSHINE (registered trademark), product number "A4300", thickness: 50 μm) as a substrate (Y) was attached to the exposed surface of the above-mentioned polymerizable composition layer to obtain a laminated body in which a release film, a polymerizable composition layer, and a substrate (Y) were laminated in this order. In addition, the storage modulus E'(23) of the substrate (Y) at 23°C was 3.0×10 ⁹ Pa, and the storage modulus E'(t) of the thermally expandable particles of the substrate (Y) at the expansion starting temperature (t) was 2.4×10 ⁹ Pa. The laminate obtained above was irradiated with ultraviolet light from the release film side at an illumination of 200 mW/cm ² and a light quantity of 2,000 mJ/cm ² (500 mJ/cm ² irradiation 4 times) to form an adhesive layer (X1), and an adhesive sheet was obtained in which the release film, the adhesive layer (X1) and the substrate (Y) were laminated in this order. The illumination and light quantity during ultraviolet irradiation are values measured using an illumination and light quantity meter (manufactured by EIT, product name "UV Power Puck II").

The following evaluations were then performed on the adhesive sheets prepared in each example. The evaluation results are shown in Table 2.

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

[Measurement of Adhesive Strength at 23°C after Thermal Expansion of Adhesive Layer (X1)] The above test sample was placed on a heating plate in such a way that the silicon mirror wafer was in contact with the heating plate and the adhesive sheet was not in contact with the heating plate. It was heated at 100°C, which is above the expansion start temperature of the thermally expandable particles, for 1 minute. After being left in a standard environment (23°C, 50% RH (relative humidity)) for 60 minutes, the adhesive strength of the adhesive layer (X1) was measured at a tensile speed of 300 mm/min by the 180° peeling method based on JIS Z0237:2000. In addition, when the adhesive sheet is fixed for measurement, the adhesive force is too small and it is not expected to be peeled off, making it difficult to measure the adhesive force, and the adhesive force is set to 0N/25mm.

[Evaluation of self-peeling property] The peeling film was removed from the adhesive layer (X1) of the adhesive sheet cut into 50mm×50mm. Based on JIS Z0237:2000, the exposed surface of the adhesive layer (X1) was bonded to the mirror surface of the silicon mirror wafer with a 2kg rubber roller. The test sample was then immediately placed in an environment of 23℃ and 50%RH (relative humidity) for 20 minutes. Next, the test sample was placed on the heating plate in such a way that the silicon mirror wafer was in contact with the heating plate and the adhesive sheet was not in contact with the heating plate, and heated at 100°C, which is 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 heating time of 60 seconds was calculated (peeled area × 100/the area of the entire adhesive sheet), and evaluated based on the following criteria. A: The entire adhesive sheet was peeled within 60 seconds. B: The peeled area was 30% or more and less than 100% after heating for 60 seconds. C: After heating for 60 seconds, the peeled area is less than 30%. In addition, for those rated "A", the time (seconds) required for the entire surface to be peeled was measured.

As shown in Table 2, the adhesive sheets of Manufacturing Examples 1 to 3 all have sufficient adhesive force before heat peeling and can also be heat peeled at a low temperature (100°C). It can also be seen that the adhesive force and self-peeling property of these adhesive sheets can be adjusted by adjusting the composition of the polymerizable composition and the thickness of the adhesive layer (X1).

[Manufacturing of semiconductor device] Example 1 Next, a semiconductor device is manufactured by the manufacturing method of this embodiment. In addition, the double-sided adhesive sheet used in the manufacturing method of the semiconductor device is manufactured by the method shown below.

[Preparation of double-sided adhesive sheet] (1) Preparation of energy-ray-curable adhesive composition (x-2) 52 parts by mass of butyl acrylate, 20 parts by mass of methyl methacrylate, and 28 parts by mass of ethyl 2-hydroxyacrylate were solution polymerized in ethyl acetate solvent to obtain a non-energy-ray-curable acrylic copolymer. Methacryloyloxyethyl isocyanate in an amount of 0.9 equivalents of isocyanate groups relative to the total number of hydroxyl groups of the obtained acrylic copolymer was added to the solution containing the acrylic copolymer and reacted to generate an energy-ray-curable acrylic copolymer (1) (Mw: 1 million) having energy-ray-polymerizable groups in the side chains. Then, with respect to 100 parts by mass of the solid content of this acrylic copolymer (1), 0.5 parts by mass (solid content ratio) of an isocyanate crosslinking agent (manufactured by Tosoh Co., Ltd., product name "Coronate L") as a crosslinking agent and 0.57 parts by mass (solid content ratio) of 1-hydroxy-cyclohexyl-phenyl-ketone (manufactured by IGM Resins, product name "Omnirad 184") as a photopolymerization initiator were mixed to prepare a solution of an energy ray-curable adhesive composition (x-2).

(2) Production of double-sided adhesive sheet An adhesive sheet prepared in Example 1 by laminating the release film, adhesive layer (X1) and substrate (Y) in sequence is prepared as adhesive sheet (1). On the other hand, the energy ray-curable adhesive composition (x-2) prepared above is applied on the release-treated surface of a polyethylene terephthalate (PET) release film (manufactured by LINTEC Co., Ltd., product name "SP-PET381031", thickness: 38μm), dried at 100°C for 1 minute, and an adhesive layer (X2) (thickness: 20μm) is formed on the release film. Then, the adhesive layer (X2) is laminated to the substrate (Y) of the adhesive sheet (1) to obtain a double-sided adhesive sheet in which a release film, an adhesive layer (X1), a substrate (Y), an adhesive layer (X2) and a release film are laminated in sequence.

[Manufacturing of semiconductor devices] (Step 1) Using a back grinding tape laminating machine (manufactured by LINTEC Co., Ltd., device name "RAD-3510F/12"), on a table at room temperature (25°C), the adhesive layer (X2) of the double-sided adhesive sheet prepared above is removed by removing the peeling film, and laminated on the electrical path surface of a wafer having a patterned electrical path surface with the adhesive layer (X2) being in contact with the electrical path surface of the wafer. On the other hand, the support body, i.e., the mirror wafer (diameter 12 inches, thickness 750 μm) is attached to the adhesive layer (X1) exposed by removing the peeling film from the adhesive layer (X1) of the double-sided adhesive sheet, to obtain a laminated body in which the support body, the double-sided adhesive sheet and the wafer are laminated in sequence.

(Step 2) Next, an invisible laser irradiation device (manufactured by DISCO Co., Ltd., device name "DFL7361") is used to perform invisible laser irradiation on the back side of the wafer opposite to the circuit formation surface, forming a modified area inside the wafer. Then, a grinder/polisher (manufactured by DISCO Co., Ltd., device name "DGP8761") is used to grind and separate the wafers from the back side of the wafer while exposing it to ultrapure water, thereby obtaining a wafer with a thickness of 20μm. In addition, during such processing, vibration and positional deviation of the object to be processed due to insufficient adhesion between the double-sided adhesive sheet and the support body are fully suppressed.

(Step 3) Next, a chip adhesive film (manufactured by LINTEC Co., Ltd., product name "Adwill LD01D-7") with a support sheet attached is attached to the back side of the individualized chip using a bonding machine (manufactured by LINTEC Co., Ltd., product name "RAD2700") at 50°C, with the back side of the chip in contact with the chip adhesive film, to obtain a laminate having a support body, an adhesive sheet, a chip, a chip adhesive film, and a support sheet in order.

(Step 4) The above-mentioned laminate is placed on the heating plate in such a manner that the support body side becomes the contact side with the heating plate, and is heated for 1 minute at 100°C, which is above the expansion start temperature of the thermally expandable particles, to separate the adhesive layer (X1) of the adhesive sheet from the support body. In addition, the adhesion between the heated adhesive layer (X1) and the support body is reduced to the extent that if the support body is facing upward and the adhesive sheet with the chip attached is facing downward, the adhesive sheet with the chip attached will fall due to its weight.

(Step 5) Next, the adhesive layer (X1) side of the adhesive sheet separated from the support and exposed is irradiated with ultraviolet light at an illumination of 230 mW/ ^cm2 and a light quantity of 380 mJ/ ^cm2 to harden the adhesive layer (X2), thereby reducing the adhesion and separating the adhesive layer (X2) from the chip. The surface of the chip separated from the adhesive layer (X2) is visually checked to confirm that there is no contamination or residual adhesive. After the chip adhesive film is divided into the same shape as the chip, the support sheet is removed to obtain individual chips with chip adhesive films attached. A die bonding machine is used to attach the die with the die bonding film to the substrate from the die bonding film side, and the die bonding film is thermally cured to fix the die and the substrate to obtain a semiconductor device.

As described above, it can be seen that the method for manufacturing a semiconductor device according to one aspect of the present invention has excellent processability and productivity of the object to be processed, and there is no contamination of the object to be processed by the thermally expandable particles and the expanded adhesive layer.

1a, 1b: Adhesive sheet 10a, 10b: Peeling material 2: Support body 3: Laser irradiation device 4: Modified area 5: Grinding machine 6: Thermosetting film 7: Support sheet W: Semiconductor wafer W1: Surface of semiconductor wafer and semiconductor chip W2: Back of semiconductor wafer and semiconductor chip CP: Semiconductor chip (X1): Adhesive layer (X1) (X2): Adhesive layer (X2) (Y): Substrate (Y)

[FIG. 1] A cross-sectional view showing an example of the structure of the adhesive sheet of the present invention. [FIG. 2] A cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 3] A cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 4] A cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 5] A cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 6] A cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 7] A cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [Fig. 8] A cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention.

1a,1b: Adhesive sheet

10a,10b: Stripping material

(X1): Adhesive layer (X1)

(X2): Adhesive layer (X2)

(Y): Base material (Y)

Claims (10)

A method for manufacturing a semiconductor device is a method for manufacturing a semiconductor device using an adhesive sheet, wherein the adhesive sheet sequentially comprises an adhesive layer (X1) containing thermally expandable particles, a substrate (Y), and an adhesive layer (X2) whose adhesive force is reduced by curing by irradiating energy rays, and the manufacturing method comprises the following steps 1 to 5, wherein the thermally expandable particles have an expansion starting temperature (t) of 50 to 100° C. Step 1: attaching a processing object to the adhesive layer (X2) of the adhesive sheet, and attaching a support to the adhesive layer (X1) of the adhesive sheet; Step 2: performing one or more processing selected from grinding and slicing on the aforementioned processing object; Step 3: attaching a thermosetting film to the surface of the processing object on the opposite side of the adhesive layer (X2) after the aforementioned processing; Step 4: heating the aforementioned adhesive sheet to a temperature above the expansion start temperature (t) of the aforementioned thermally expandable particles and below 110°C, and separating the adhesive layer (X1) from the aforementioned support; Step 5: irradiating the adhesive layer (X2) with energy rays, and separating the adhesive layer (X2) from the aforementioned processing object. A method for manufacturing a semiconductor device as claimed in claim 1, wherein the aforementioned processing is individualization processing by invisible cutting method, grinding processing and individualization processing by blade pre-cutting method, or grinding processing and individualization processing by invisible pre-cutting method. A method for manufacturing a semiconductor device as claimed in claim 1 or 2, wherein the aforementioned processing is grinding processing and individual wafer processing performed by invisible pre-cutting method. A method for manufacturing a semiconductor device as claimed in claim 1 or 2, wherein the content of the aforementioned thermally expandable particles is 1 to 30 mass % relative to the total mass (100 mass %) of the adhesive layer (X1). The method for manufacturing a semiconductor device according to claim 1 or 2, wherein the average particle size (D ₅₀ ) of the thermally expandable particles at 23° C. is 1 to 30 μm. The method for manufacturing a semiconductor device according to claim 1 or 2, wherein the storage modulus E'(23) of the substrate (Y) at 23°C is 5.0×10 ⁷ ~5.0×10 ⁹ Pa. A method for manufacturing a semiconductor device as claimed in claim 1 or 2, wherein the object to be processed is a semiconductor wafer. A method for manufacturing a semiconductor device as claimed in claim 1 or 2, wherein the energy rays are ultraviolet rays. A method for manufacturing a semiconductor device as claimed in claim 1 or 2, wherein in the aforementioned step 4, the aforementioned adhesive sheet is heated from the aforementioned support body side. A method for manufacturing a semiconductor device as claimed in claim 1 or 2, wherein in the aforementioned step 4, a heating plate is used to heat the supporting body side of the aforementioned adhesive sheet.

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