TWI868118B - Adhesive sheet, method for manufacturing adhesive sheet, and method for manufacturing semiconductor device - Google Patents

Abstract

The present invention relates to an adhesive sheet, which is an adhesive sheet having a substrate (Y), and an adhesive layer (X1) containing a polymer of an energy ray polymerizable component and thermally expandable particles having an expansion starting temperature (t) of 50 to 110°C. The adhesive layer (X1) is a layer formed by irradiating a polymerizable composition containing the aforementioned energy ray polymerizable component and the aforementioned thermally expandable particles with energy rays to form a polymer of the aforementioned energy ray polymerizable component.

Description

Adhesive sheet, method for manufacturing adhesive sheet, and method for manufacturing semiconductor device

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

Adhesive sheets are not only used for semi-permanently fixing components, but also used as temporary fixing sheets to temporarily fix components (hereinafter also referred to as "attachment objects") that are the objects of processing or inspection when processing or inspecting building materials, interior materials, electronic parts, etc. For example, in the manufacturing process of semiconductor devices, temporary fixing sheets are used when processing semiconductor wafers.

In the manufacturing process of semiconductor devices, semiconductor wafers are processed into semiconductor chips through a grinding step of thinning the thickness by grinding, a singulation step of singulation by cutting and separation, etc. At this time, the semiconductor wafer is subjected to a specified process in a temporarily fixed state with respect to a temporary fixing sheet. The semiconductor chip obtained by the specified process is separated from the temporary fixing sheet, and if necessary, after appropriately performing an expansion step of expanding the interval between semiconductor chips, a re-arrangement step of arranging a plurality of semiconductor chips with expanded intervals, a reversal step of reversing the front and back sides of the semiconductor chip, etc., it is mounted on a substrate. In each of the above steps, a temporary fixing sheet suitable for individual purposes can be used.

Patent document 1 discloses a heat-peelable adhesive sheet for temporarily fixing electronic components when they are cut, wherein a heat-expandable adhesive layer containing heat-expandable microspheres is provided on at least one side of a substrate. In the same document, it is described that the heat-peelable adhesive sheet can prevent chip flying and other bonding failures by ensuring a contact area of a specified size with the adherend when the electronic components are cut. After use, the heat-expandable microspheres are expanded by heating, thereby reducing the contact area with the adherend and making it easy to peel off. [Prior technical document] [Patent document]

[Patent Document 1] Japanese Patent No. 3594853

[Problems to be solved by the invention]

However, when mounting a semiconductor chip on a substrate, the semiconductor chip is attached to the substrate through a thermosetting film adhesive called die attach film (hereinafter also referred to as "DAF"). DAF is attached to one side of a semiconductor wafer or a plurality of singulated semiconductor chips, and is divided into the same shape as the semiconductor chip at the same time as the singulation of the semiconductor wafer or after being attached to the semiconductor chip. The semiconductor chip with DAF obtained by singulation is attached (die-bonded) to the substrate from the DAF side, and then the DAF is thermally cured to fix the semiconductor chip and the substrate. At this time, it is necessary to maintain the properties of pressure-sensitive or heat-bonding until the DAF is attached to the substrate.

The heat-peelable adhesive sheet disclosed in Patent Document 1 is peeled off from the adhered body by expanding heat-expandable microspheres to form bumps and depressions on the adhesive surface. The adhesive sheet can reduce the contact area between the adhesive layer and the semiconductor chip by forming bumps and depressions. Therefore, compared with a temporary fixing sheet that hardens the adhesive layer by energy ray irradiation to reduce the adhesive force, it has the advantage of being peeled off from the adhered body with less force. However, when a semiconductor chip with DAF is used as the object to be attached to a heat-peel adhesive sheet, the heat applied to expand the heat-expandable microspheres causes the DAF to harden before die bonding, which reduces the adhesion of the DAF to the substrate. The reduction in the adhesion of the DAF leads to a reduction in the bonding reliability between the semiconductor chip and the substrate, so it is desired to suppress this. On the other hand, in order to suppress the hardening of the DAF before die bonding, when heat-expandable microspheres with a low expansion starting temperature are used as heat-expandable microspheres for the heat-peel adhesive sheet in a manner that allows heat peeling at a low temperature, problems such as the heat-expandable microspheres being inadvertently expanded may occur during the manufacturing process of the adhesive sheet. As a result, there are cases where the adhesive force is easily reduced, and spaces are formed during attachment (air exists between the adhered object and the adhesive sheet), thereby impairing the performance of the sheet as a temporary fixing sheet.

The present invention is made in view of the above-mentioned problems, and aims to provide an adhesive sheet that has sufficient adhesive force when temporarily fixed and can be thermally peeled even at low temperatures, a method for manufacturing the adhesive sheet, and a method for manufacturing a semiconductor device using the adhesive sheet. [Means for solving the problem]

The inventors of the present invention have found that the above-mentioned problem can be solved by an adhesive layer having a substrate, a polymer containing an energy ray polymerizable component, and heat-expandable particles having an expansion starting temperature within a specific range, wherein the adhesive layer is an adhesive sheet formed by irradiating a polymerizable composition containing the energy ray polymerizable component and the heat-expandable particles with energy rays to form a polymer of the energy ray polymerizable component. That is, the present invention relates to the following [1] to [15]. [1] An adhesive sheet comprising a substrate (Y), and an adhesive layer (X1) containing a polymer of an energy ray polymerizable component and heat-expandable particles having an expansion starting temperature (t) of 50 to 110°C, wherein the adhesive layer (X1) is a layer formed by irradiating a polymerizable composition containing the energy ray polymerizable component and the heat-expandable particles with energy ray to form a polymer of the energy ray polymerizable component. [2] The adhesive sheet as described in [1] above, wherein the content of the heat-expandable particles is 1 to 30% by mass relative to the total mass (100% by mass) of the adhesive layer (X1). [3] The adhesive sheet as described in [1] or [2] above, wherein the thickness of the adhesive layer (X1) at 23°C is 5 to 150 μm. [4] The adhesive sheet as described in any one of [1] to [3] above, wherein the adhesive force of the adhesive layer (X1) at 23°C is 0.1 to 12.0 N/25 mm. [5] The adhesive sheet as described in any one of [1] to [4] above, wherein the average particle size of the thermally expandable particles at 23°C is 1 to 30 μm. [6] The adhesive sheet as described in any one of [1] to [5] above, comprising a substrate (Y), an adhesive layer (X1) disposed on a surface of one side of the substrate (Y), and an adhesive layer (X2) disposed on a surface of the other side of the substrate (Y). [7] An adhesive sheet as described in [6] above, wherein the adhesive layer (X2) is an adhesive layer whose adhesive force is reduced by curing by irradiation with energy rays. [8] A method for manufacturing an adhesive sheet, which is a method for manufacturing an adhesive sheet as described in any one of [1] to [7] above, characterized in that a method for forming the adhesive layer (X1) comprises irradiating a polymerizable composition containing the aforementioned energy ray polymerizable component and the aforementioned thermally expandable particles with energy rays to form a polymer of the aforementioned energy ray polymerizable component. [9] The method for producing an adhesive sheet as described in [8] above, wherein the method for forming the adhesive layer (X1) comprises the following steps I and II: Step I: forming a polymerizable composition layer comprising the polymerizable composition on one side of the substrate (Y); Step II: forming a polymer of the energy ray polymerizable component by irradiating the polymerizable composition layer with energy rays, and forming an adhesive layer (X1) containing the polymer and the thermally expandable particles. [10] The method for producing an adhesive sheet as described in [8] or [9] above, wherein the polymerizable composition does not contain a solvent. [11] A method for manufacturing an adhesive sheet as described in any one of the above [8] to [10], which does not include a step of heating the aforementioned polymerizable composition. [12] A method for manufacturing a semiconductor device, which includes: attaching a processing object to the adhesive sheet as described in any one of the above [1] to [7], subjecting the aforementioned processing object to one or more treatments selected from a grinding treatment and a singulation treatment, and, after the aforementioned treatments are performed, heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C, thereby causing the adhesive layer (X1) to expand. [13] A method for manufacturing a semiconductor device, comprising the following steps 1A to 5A, Step 1A: attaching a processing object to the adhesive layer (X2) of the adhesive sheet as described in [6] above, and attaching a support to the adhesive layer (X1) of the adhesive sheet Step 2A: performing one or more of a grinding process and a singulation process on the processing object Step 3A: A step of attaching a thermosetting film having thermosetting properties to the surface of the aforementioned adhesive layer (X2) on the opposite side of the processing object to be processed as described above Step 4A: A step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C, and separating the adhesive layer (X1) from the aforementioned support Step 5A: A step of separating the adhesive layer (X2) from the aforementioned processing object. [14] A method for manufacturing a semiconductor device as described in [13] above, wherein the adhesive layer (X2) is hardened by irradiating energy rays to reduce the adhesive force, and the aforementioned step 5A is a step of separating the adhesive layer (X2) from the aforementioned processing object by irradiating the adhesive layer (X2) with energy rays to harden the adhesive layer (X2). [15] A method for manufacturing a semiconductor device, comprising the following steps 1B to 4B, Step 1B: attaching a processing object to the adhesive layer (X1) of the adhesive sheet as described in [6] above, and attaching a support to the adhesive layer (X2) of the aforementioned adhesive sheet Step 2B: performing a self-milling process and a singulation process on the aforementioned processing object Step 3B: A step of attaching a thermosetting film having thermosetting properties to the surface of the aforementioned adhesive layer (X1) of the object to be processed to which the aforementioned treatment is applied Step 4B: A step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C, and separating the adhesive layer (X1) from the aforementioned object to be processed. [Effect of the invention]

The present invention can provide an adhesive sheet which has sufficient adhesive force when temporarily fixed and can be thermally peeled even at low temperatures, a method for manufacturing the adhesive sheet, and a method for manufacturing a semiconductor device using the adhesive sheet.

In this specification, the so-called "active ingredient" refers to the component contained in the target composition, 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 according to the method described in the embodiment.

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, for the preferred numerical range (such as the range of content, etc.), the lower limit value and the upper limit value recorded in stages can be combined independently. For example, from the so-called "preferably 10 to 90, more preferably 30 to 60", it is also possible to combine "preferably the lower limit value (10)" and "preferably the upper limit value (60)" to set it to "10 to 60".

In this specification, the so-called "energy line" means an electromagnetic wave or charged particle line with energy quanta, and examples thereof include ultraviolet rays, radiation, electron beams, etc. Ultraviolet rays 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 so-called "energy line polymerization" means the property of polymerization by irradiation with energy lines.

In this specification, whether a "layer" is a "non-thermal expansion layer" or a "thermal expansion layer" is determined as follows. When the layer to be determined contains thermal expansion particles, the layer is heated for 3 minutes at the expansion starting 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, the layer that does not contain thermal expansion particles is defined as a "non-thermal expansion layer".

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

[Adhesive sheet] An adhesive sheet according to one embodiment of the present invention is an adhesive sheet having a substrate (Y), and an adhesive layer (X1) containing a polymer of an energy ray polymerizable component and heat-expandable particles having an expansion starting temperature (t) of 50 to 110°C. The adhesive layer (X1) is a layer formed by irradiating a polymerizable composition containing the energy ray polymerizable component and the heat-expandable particles with energy ray to form a polymer of the energy ray polymerizable component.

An adhesive sheet according to one aspect of the present invention is formed by heating the heat-expandable particles contained in the adhesive layer (X1) to a temperature above the expansion starting temperature (t) and causing them to expand, thereby forming bumps and depressions on the adhesive surface of the adhesive layer (X1) and allowing the adhesive sheet to be peeled off from a target object. The adhesive sheet according to one aspect of the present invention can reduce the contact area between the adhesive layer (X1) and the target object by forming the bumps and depressions, thereby significantly reducing the adhesion between the adhesive sheet and the target object. As a result, when the adhesive sheet according to one aspect of the present invention is peeled off by heat, it is not necessary to apply a peeling force, and the adhesive sheet can be peeled off from a target object by the self-weight of the adhesive sheet or the self-weight of the target object. Specifically, for example, when the adhesive sheet of one aspect of the present invention is peeled off from the adhered object by heating, the adhesive sheet side is turned downward, and the adhesive sheet is dropped from the adhered object by gravity to be peeled off. In this specification, the state of the adhesive sheet being peeled off from the adhered object or peeling off is called "self-peeling" instead of applying a peeling force to the adhesive sheet. In addition, such a property is defined as "self-peeling property". As described above, since the adhesive sheet of one aspect of the present invention reduces the contact area between the adhesive layer (X1) and the adherend during heat peeling, it has excellent self-peeling properties compared to a temporary fixing sheet that hardens the adhesive layer by energy ray irradiation to reduce the adhesive force.

In addition, since the expansion starting temperature (t) of the heat-expandable particles contained in the adhesive layer (X1) is below 110°C, which is a low temperature, the adhesive sheet of one aspect of the present invention can be peeled off by heating at a low temperature. Therefore, when a semiconductor chip with DAF is used as a heat-sensitive object, the thermal change caused by heating during thermal peeling can be suppressed. On the other hand, by setting the expansion starting temperature (t) of the heat-expandable particles to above 50°C, the expansion of the heat-expandable particles can be suppressed by raising the temperature of the object when grinding it. In addition, the adhesive layer (X1) possessed by the adhesive sheet of one embodiment of the present invention is a layer formed by irradiating a polymerizable composition containing energy ray polymerizable components and thermally expandable particles with energy ray to form a polymer of the aforementioned energy ray polymerizable components. Since the polymerizable composition is polymerized to a high molecular weight by subsequent energy ray polymerization, it can contain low molecular weight energy ray polymerizable components when forming the layer. Therefore, the polymerizable composition can be adjusted to a viscosity suitable for coating even without using a solvent such as a diluent. As a result, when using the polymerizable composition to form the adhesive layer (X1), the heat drying for removing the solvent can be omitted, and the unexpected expansion of the thermally expandable particles during heat drying can be suppressed.

The adhesive sheet of one aspect of the present invention may have a substrate (Y) and an adhesive layer (X1), but may have layers other than the substrate (Y) and the adhesive layer (X1) depending on the application. For example, when the adhesive sheet of one aspect of the present invention is used for processing of an adherend, from the viewpoint of improving the processability of the adherend, it is preferably configured as follows (i.e., a double-sided adhesive sheet), the configuration comprising a substrate (Y), an adhesive layer (X1) disposed on one side of the substrate (Y), and an adhesive layer (X2) disposed on the other side of the substrate (Y). By having this structure, a to-be-attached body can be attached to the adhesive layer on either side of the adhesive layer (X1) or the adhesive layer (X2), and a support can be attached to the other adhesive layer of either. The to-be-attached body is fixed to the support through the adhesive sheet, and when the to-be-attached body is processed, vibration, positional displacement, damage to fragile processing objects, etc. of the to-be-attached body can be suppressed, and processing accuracy and processing speed can be improved. In the following description, unless otherwise specified, the so-called "double-sided adhesive sheet" means an adhesive sheet having a substrate (Y), an adhesive layer (X1) disposed on one side of the substrate (Y), and an adhesive layer (X2) disposed on the other side of the substrate (Y).

The adhesive sheet of one aspect of the present invention may have a release material on the adhesive surface of the adhesive layer (X1). In addition, when the adhesive sheet of one aspect of the present invention has a double-sided adhesive sheet, the release material may be on the adhesive surface of at least one of the adhesive layer (X1) and the adhesive layer (X2).

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

[Structure of adhesive sheet] As one aspect of the adhesive sheet of the present invention, there can be cited an adhesive sheet 1a having an adhesive layer (X1) on a substrate (Y) as shown in FIG. 1(a). In addition, an adhesive sheet of one aspect of the present invention, such as an adhesive sheet 1b as shown in FIG. 1(b), can be further configured to have a release material 10 on the adhesive surface of the adhesive layer (X1).

As another aspect of the adhesive sheet of the present invention, the above-mentioned double-sided adhesive sheet can be cited. As an adhesive sheet having such a structure, for example, a double-sided adhesive sheet 2a having a structure in which a substrate (Y) is clamped by an adhesive layer (X1) and an adhesive layer (X2) as shown in FIG. 2(a) can be cited. In addition, a double-sided adhesive sheet 2b as shown in FIG. 2(b) can be 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 the double-sided adhesive sheet 2b shown in FIG. 2(b), when the peeling force when peeling the peeling material 10a from the adhesive layer (X1) and the peeling force when peeling the peeling material 10b from the adhesive layer (X2) are the same, when the peeling materials on both sides are pulled outward for peeling, the adhesive layer is separated along with the two peeling materials, resulting in peeling phenomenon. From the viewpoint of suppressing such a phenomenon, it is preferable to use two kinds of peeling materials designed so that the peeling forces from the adhesive layers of the two peeling materials 10a and 10b attached to each other are different.

As another form of adhesive sheet, it can be a double-sided adhesive sheet, which is a double-sided adhesive sheet 2a shown in Figure 2(a), in which the adhesive surface of one side of the adhesive layer (X1) and the adhesive layer (X2) has a peeling material layered on both sides and subjected to peeling treatment and is rolled into a roll.

The adhesive sheet of one aspect of the present invention may or may not have other layers between the substrate (Y) and the adhesive layer (X1). Furthermore, when the adhesive sheet of one aspect of the present invention is the above-mentioned two-sided adhesive sheet, in addition to the above, it 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 expansion on the surface opposite to the adhesive surface of the adhesive layer (X1), and it is more preferred to directly laminate the substrate (Y).

<Substrate (Y)> The material for forming the substrate (Y) may include resin, metal, paper, etc., and may be appropriately selected according to the purpose of the adhesive sheet of one aspect 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 transparent paper. Among these, preferred are polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate.

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

From the viewpoint 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, and primer treatment. As oxidation methods, for example, there are 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, for example, there are sandblasting and solvent treatment methods.

The substrate (Y) and the above-mentioned resin together serve as a substrate additive, and may contain, for example, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, slip agents, anti-blocking agents, coloring agents, etc. These substrate additives may be used separately or in combination of two or more. When the substrate (Y) and the above-mentioned resin contain a substrate additive together, 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%, still more preferably less than 0.1%, and still more preferably less than 0.01%.

Although the substrate (Y) may contain heat-expandable particles within the scope not violating the purpose of the present invention, it is preferred that the substrate (Y) does not contain heat-expandable particles. When the substrate (Y) contains heat-expandable particles, the content thereof is preferably as small as possible, and is 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 more preferably less than 0.001% by mass relative to the total mass of the substrate (Y) (100% by mass).

(Storage elasticity E'(23) of substrate (Y) at 23°C) The storage elasticity E'(23) of the 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 even more preferably 1.0×10 ⁹ to 4.0×10 ⁹ Pa. If the storage elasticity E'(23) of the substrate (Y) is 5.0×10 ⁷ Pa or more, expansion of the surface of the adhesive layer (X1) on the substrate (Y) side can be effectively suppressed, and deformation resistance of the adhesive sheet can be improved. On the other hand, if the storage elasticity 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 this specification, the storage elasticity E'(23) of the substrate (Y) refers to a value measured by the method described in the examples.

(Storage elastic modulus E'(t) of substrate (Y) at expansion starting temperature (t)) The storage elastic modulus E'(t) of the thermally expandable particles of the substrate (Y) at the expansion starting temperature (t) is preferably 5.0×10 ⁶ to 4.0×10 ⁹ Pa, more preferably 2.0×10 ⁸ to 3.0×10 ⁹ Pa, and even more preferably 5.0×10 ⁸ to 2.5×10 ⁹ Pa. If the storage elastic modulus E'(t) of the 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 elasticity E'(t) of the substrate (Y) is 4.0×10 ⁹ Pa or less, the handling property of the adhesive sheet can be improved. In this specification, the storage elasticity E'(t) of the substrate (Y) refers to the value measured by the method described in the examples.

(Thickness of substrate (Y)) The thickness of substrate (Y) is preferably 5 to 500 μm, more preferably 15 to 300 μm, and even more preferably 20 to 200 μm. If the thickness of substrate (Y) is 5 μm or more, the deformation resistance of the adhesive sheet can be improved. On the other hand, if the thickness of substrate (Y) is 500 μm or less, the operability of the adhesive sheet can be improved. 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 a polymer containing an energy ray polymerizable component and thermally expandable particles. The polymer as the energy ray polymerizable component is a polymer obtained by irradiating a polymerizable composition (hereinafter also referred to as "polymerizable composition (x-1)") containing 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") with energy ray. In this specification, the so-called prepolymer means a compound formed by polymerizing a monomer, and a compound that can constitute a polymer by further polymerization.

(Polymerizable composition (x-1)) The energy-ray polymerizable component contained in the polymerizable composition (x-1) is a component that is polymerized by irradiation with energy rays and has an energy-ray polymerizable functional group. As energy-ray polymerizable functional groups, for example, (meth)acryl, vinyl, allyl, etc. having a carbon-carbon double bond can be listed. In addition, in this specification, such as (meth)acryl, allyl, etc., some of which include a vinyl or a substituted vinyl functional group, and the vinyl or the substituted vinyl itself are collectively referred to as "vinyl-containing groups". Below, each component contained in the polymerizable composition (x-1) is explained.

[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 hydrocarbon group, a functional group other than energy-ray polymerizable functional groups, etc. in addition to energy-ray polymerizable functional groups.

Examples of the alkyl group possessed by the component (a1) include aliphatic alkyl groups, aromatic alkyl groups, and groups combining these groups. The aliphatic alkyl group may be a linear or branched aliphatic alkyl group, or may be 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, tert-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 alicyclic alkyl groups include alicyclic alkyl groups having 3 to 20 carbon atoms such as cyclopentyl, cyclohexyl, and isoborneol. Examples of aromatic alkyl groups include phenyl. Examples of groups combining aliphatic alkyl groups and aromatic alkyl groups include phenoxyethyl and benzyl. Among these, from the viewpoint of further enhancing the adhesive force of the adhesive layer (X1), the component (a1) is preferably a monomer (a1-1) containing an energy ray-polymerizable functional group and a linear or branched chain aliphatic hydrocarbon group (hereinafter also referred to as "component (a1-1)"), a monomer (a1-2) containing an energy ray-polymerizable functional group and an alicyclic hydrocarbon group (hereinafter also referred to as "component (a1-2)"), etc.

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

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

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 component (a1), the cohesive force of the adhesive obtained by polymerizing these is increased, and an adhesive layer (X1) with less contamination of the adhered object after peeling can be formed.

《Polymerizable vinyl monomer》 As for 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, a polymerizable vinyl monomer having a hydroxyl group equivalent 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.

In addition, examples of other polymerizable vinyl monomers include vinyl esters such as vinyl acetate and vinyl propionate; olefins such as ethylene, propylene, and isobutylene; halogenated olefins such as vinyl chloride and vinylidene chloride; styrene 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.

《Polyfunctional (meth)acrylate monomer》 As a polyfunctional (meth)acrylate monomer, if it is a monomer having two or more (meth)acryl groups in one molecule, it is not particularly limited, and conventionally known monomers can be appropriately used. The polyfunctional (meth)acrylate monomer can be used alone or in combination of two or more.

Examples of the multifunctional (meth)acrylate monomer include 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, hydroxy neopentyl glycol di(meth)acrylate, dicyclopentyl (pentanyl) di(meth)acrylate, caprolactone-modified dicyclopentenyl di(meth)acrylate, ethylene oxide-modified phosphoric acid di(meth)acrylate, di(acryloyloxyethyl) isocyanurate, allylated cyclohexyl di(meth)acrylate, isocyanuric acid ethylene oxide-modified diacrylate, and the like; trihydroxymethylpropane tri(meth)acrylate; ester, dipentaerythritol 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)hydroxyethyl isocyanurate, 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, and a multifunctional (meth)acrylate monomer corresponding to the above-mentioned component (a1-4).

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

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

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

《Multifunctional (meth)acrylate prepolymer》 As a multifunctional (meth)acrylate prepolymer, if it is a prepolymer having two or more (meth)acryl groups in one molecule, it is not particularly limited, 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 polyacryl acrylate prepolymers.

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

Examples of polyalkylene glycols used in the preparation of urethane acrylate prepolymers include polypropylene glycol, polyethylene glycol, polybutylene glycol, polyethylene glycol, etc. Among them, polypropylene glycol is preferred. When the functional group number of the obtained urethane acrylate prepolymer is set to 3 or more, for example, glycerol, 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 tolylene diisocyanate, xylene 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 may 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 them, 2-isocyanate ethyl acrylate is preferred.

As another method for producing the urethane acrylate prepolymer, there can be cited a method of reacting the 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, and the -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 groups 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, it can be obtained by esterifying the terminal hydroxyl groups of a prepolymer obtained by adding an alkyl oxide to a polycarboxylic acid with (meth)acrylic acid.

Epoxy acrylate prepolymers can be obtained by, for example, reacting (meth)acrylic acid with oxirane rings of relatively low molecular weight bisphenol epoxy resins, novolac epoxy resins, etc. to form esters. Alternatively, carboxyl-modified epoxy acrylate prepolymers in which epoxy acrylate prepolymers are partially modified 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 polyacryl acrylate prepolymer may have an acryl group in the side chain, or may have an acryl group at both ends or at one end. The polyacryl acrylate prepolymer having an acryl group in the side chain is obtained, for example, by adding glycidyl methacrylate to the carboxyl group of polyacrylic acid. Furthermore, the polyacryl acrylate prepolymer having an acryl group at both ends can be obtained, for example, by polymerizing a polyacrylate prepolymer synthesized by the ATRP (Atom Transfer Radical Polymerization) method to form an end structure and introducing an acryl group at both ends.

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

The content ratio of the components (a2) and (a1) in the polymerizable composition (x-1) [(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, it is preferred that the polymerizable composition (x-1) 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 component contained in the polymerizable composition (x-1) is preferably 80% by mass or more, more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 99% by mass or more, and may also be 100% by mass, relative to the total amount of the energy ray polymerizable component (100% by mass).

The total content of the energy ray polymerizable components in the polymerizable composition (x-1) is preferably 70 to 98 mass %, more preferably 75 to 97 mass %, further preferably 80 to 96 mass %, and further preferably 82 to 95 mass %, relative to the total amount (100 mass %) of the effective components of the polymerizable composition (x-1).

[Thermal expansion particles] Thermal expansion particles are particles whose expansion starting temperature (t) is adjusted to 50-110°C. The expansion starting temperature (t) of the thermal expansion particles can be appropriately adjusted within the above range according to the use 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 adherend, it is preferably 55°C or more, more preferably 60°C or more, and more preferably 70°C or more. From the perspective of suppressing the thermal change of the adherend during thermal peeling, it is preferably 105°C or less, more preferably 100°C or less, and more preferably 95°C or less. In this specification, the expansion starting temperature (t) of the thermal expansion particles means the value measured according to the following method. [Method for measuring the expansion starting temperature (t) of thermal expansion particles] An aluminum cup with a diameter of 6.0 mm (inner diameter of 5.65 mm) and a depth of 4.8 mm was prepared, and 0.5 mg of thermal expansion particles as the test object was added, and an aluminum cover (diameter of 5.6 mm, thickness of 0.1 mm) was attached to it. The dynamic viscoelasticity measuring device was used to measure the height of the sample by applying a force of 0.01 N from the top of the aluminum cover with a press. Furthermore, the pressure plate was heated from 20°C to 300°C at a heating rate of 10°C/min under a force of 0.01N, and the displacement of the pressure plate in the vertical direction was measured. The displacement starting temperature in the positive direction was defined as the expansion starting temperature (t).

As the heat-expandable particles, microencapsulated foaming agents are preferably used, which are composed of an outer shell composed of a thermoplastic resin and an inner component, and the inner component is encapsulated in the outer shell and vaporized when heated to a specified temperature. The thermoplastic resin constituting the outer shell of the microencapsulated foaming agent is not particularly limited. At the expansion starting temperature (t) of the heat-expandable particles, i.e., 50 to 110°C, the material and composition that can produce state changes such as melting, dissolving, and rupture can be 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 listed. These thermoplastic resins may be used alone or in combination of two or more.

As the component encapsulated in the outer shell of the microcapsule foaming agent, i.e., the inner component, any component that expands at the expansion starting temperature (t) of the thermal expansion particles, i.e., 50 to 110°C, can be used. For example, low-boiling liquids such as propane, propylene, butylene, n-butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, n-heptane, n-octane, cyclopropane, cyclobutane, and petroleum ether can be listed. Such inner components can be used alone or in combination of two or more. The expansion starting temperature (t) of the thermal expansion particles can be adjusted by appropriately selecting the type of inner component.

The average particle size 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. The so-called average particle size (D ₅₀ ) of the heat-expandable particles is the volume median particle size (D ₅₀ ), which means the particle size at which the cumulative volume frequency calculated from the smaller particle size is equivalent to 50% in the particle distribution of the heat-expandable particles before expansion measured using a laser diffraction particle size distribution measuring device (e.g., Master Sizer 3000 manufactured by Malvern Corporation).

The 90% particle size (D ₉₀ ) of the heat-expandable particles at 23° C. before heat 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. The 90% particle size (D ₉₀ ) of the heat-expandable particles refers to the particle size of which the cumulative volume frequency calculated from the smaller particle size in the particle distribution of the heat-expandable particles before expansion measured using the laser diffraction particle size distribution measuring device is equivalent to 90%.

The maximum volume expansion ratio when the heat-expandable particles are heated to a temperature higher than the expansion starting 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 even more preferably 3 to 20 mass%, relative to the total mass (100 mass%) of the effective ingredients of the polymerizable composition (x-1) or 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 workability.

[Other components] The polymerizable composition (x-1) may contain other components other than the energy ray polymerizable component and the thermally expandable particles. As the above-mentioned other components, there can be listed photopolymerization initiators, adhesion-imparting agents, adhesive additives used in general adhesives other than the above-mentioned components, etc. Among these, it is preferred that the polymerizable composition (x-1) contains a photopolymerization initiator.

《Photopolymerization initiator》 By including a photopolymerization initiator in the polymerizable composition (x-1), the polymerization of the energy ray polymerizable component can be carried out more efficiently.

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, and 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-methylthiazone, 2-ethylthiazone, 2-chlorothiazone, 2,4-dimethylthiazone, 2,4-diethylthiazone, 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-1) 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 even more 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, it is possible to eliminate or reduce the photopolymerization initiator that remains directly unreacted, making it easy to adjust the obtained adhesive layer (X1) to the desired physical properties.

《Adhesion-imparting agent》 An adhesion-imparting agent is a component used if necessary to further enhance adhesion. In this specification, the so-called "adhesion-imparting agent" refers to a substance having a mass average molecular weight (Mw) of less than 10,000, which is distinguished from the adhesive resin described later. The mass average molecular weight (Mw) of the adhesion-imparting agent 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 resins, terpene resins, styrene resins, C5 petroleum resins obtained by copolymerizing C5 distillates of pentene, isoprene, piperine, 1,3-pentadiene, etc. generated by thermal decomposition of petroleum naphtha, C9 petroleum resins obtained by copolymerizing C9 distillates of indene, vinyltoluene, etc. generated by thermal decomposition of petroleum naphtha, and hydrogenated resins obtained by hydrogenating these.

The softening point of the adhesive agent is preferably 60 to 170°C, more preferably 65 to 160°C, and even more preferably 70 to 150°C. In this specification, the "softening point" of the adhesive agent means the value measured in accordance with JIS K 2531. An adhesive agent may be used alone, or two or more adhesive agents having different softening points, structures, etc. may be used in combination. When two or more adhesive agents are used, it is preferred that the weighted average of the softening points of the multiple adhesive agents falls within the above range.

When the polymerizable composition (x-1) contains an adhesion-imparting agent, its content is preferably 0.01 to 65 mass %, more preferably 0.1 to 50 mass %, further preferably 1 to 40 mass %, and further preferably 2 to 30 mass % relative to the total amount (100 mass %) of the active ingredients of the polymerizable composition (x-1).

《Additives for Adhesives》 As additives for adhesives, for example, 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 polymerizable composition (x-1) 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, based on 100 parts by mass of the energy ray polymerizable component.

In addition, the polymerizable composition (x-1) may contain a solvent such as a diluent within the scope that does not violate the purpose of the present invention, but it is preferably free of solvent. That is, the polymerizable composition (x-1) is preferably a solvent-free polymerizable composition. Since the polymerizable composition (x-1) is a solvent-free polymerizable composition, when forming the adhesive layer (X1), the heat drying of the solvent can be omitted, so the expansion of the heat-expandable particles during heat drying can be suppressed. In addition, when a solvent is used, the heat-expandable particles are biased to one side of the surface as the volume decreases during drying, and there is a situation where the adhesion to the substrate (Y) or the adhesion of the adhesive surface is reduced. On the other hand, since the solvent-free polymerizable composition directly polymerizes in the energy ray polymerizable component in a state where the thermally expandable particles are uniformly dispersed to form the adhesive layer (X1), it is difficult to cause the above-mentioned problems. When the polymerizable composition (x-1) 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-1).

The polymerizable composition (x-1) can be produced by mixing energy ray polymerizable components, thermally expandable particles, and other components if necessary. Since the obtained polymerizable composition (x-1) is a high molecular weight one through subsequent energy ray polymerization, when forming a layer, it can be adjusted to an appropriate viscosity by low molecular weight energy ray polymerizable components. Therefore, the polymerizable composition does not need to add a solvent such as a diluent, but can be directly used as a coating solution and can be used in the formation of an adhesive layer (X1). Furthermore, although the adhesive layer (X1) formed by irradiating the polymerizable composition (x-1) with energy rays contains a variety of polymers formed by polymerizing energy ray polymerizable components and thermally expandable particles dispersed in the polymers, it is impossible or almost impractical to directly specify these by structure and physical properties.

(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 to 12.0 N/25mm, more preferably 0.5 to 9.0 N/25mm, still more preferably 1.0 to 8.0 N/25mm, and still more preferably 1.2 to 7.5 N/25mm. If the adhesion at 23°C before thermal expansion of adhesive layer (X1) is 0.1 N/25mm or more, unintentional peeling of the adherend during temporary fixation, positional displacement of the adherend, etc. can be more effectively suppressed. 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 this specification, the adhesive force of the adhesive layer refers to the adhesive force to the mirror surface of the silicon mirror wafer. In this specification, the adhesive force of the adhesive layer (X1) at 23°C before thermal expansion specifically refers to the value measured by the method described in the embodiment.

(Adhesion of the adhesive layer (X1) at 23°C after thermal expansion) The adhesion of the adhesive layer (X1) at 23°C after thermal expansion is preferably 1.5N/25mm or less, more preferably 0.05N/25mm or less, still more preferably 0.01N/25mm or less, and still more preferably 0N/25mm. The so-called adhesion of 0N/25mm in the method for measuring the adhesion at 23°C after thermal expansion described below means the adhesion below the measurement limit. For the purpose of measurement, when fixing the adhesive sheet, it also includes the case where the adhesion is too small and it is accidentally peeled off. In this specification, the adhesive force of the adhesive layer (X1) at 23° C. after thermal expansion specifically refers to 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 even more 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 adhesive layer (X1) to the adherend 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 makes it easier to form irregularities on the surface of the adhesive layer (X1), which tends to improve the peeling property during thermal peeling. 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 viewpoint of measuring the shear storage modulus G' excluding the influence of the thermally expandable particles, an adhesive layer having the same structure as the adhesive layer (X1) except that the adhesive layer does not contain thermally expandable particles (hereinafter also referred to as "non-expandable adhesive layer (X1')") may be prepared to measure the shear storage modulus G' of the adhesive layer.

(Shear storage modulus G'(23) of 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 even more preferably 1.0×10 ⁵ to 5.0×10 ⁶ Pa. If the shear storage modulus G'(23) of the non-expandable adhesive layer (X1') is 1.0×10 ⁴ Pa or more, it is possible to suppress the positional displacement of the adherend during temporary fixing and the excessive sinking of the adhesive layer (X1) relative to the adherend. On the other hand, if the shear storage modulus G'(23) is 5.0×10 ⁷ Pa or less, it becomes easier to form irregularities on the surface of the adhesive layer (X1) due to the expansion of the thermally expandable particles, and there is a tendency to improve the peeling property during thermal peeling.

(Shear storage modulus G'(t) of the non-expanding adhesive layer (X1') at the expansion starting temperature (t)) The shear storage modulus G'(t) of the non-expanding adhesive layer (X1') at the expansion starting temperature (t) of the aforementioned thermally expandable particles 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 even more preferably 5.0×10 ⁴ to 1.0×10 ⁶ Pa. If the shear storage modulus G'(t) of the non-expandable adhesive layer (X1') is 5.0×10 ³ Pa or more, the positional deviation of the adherend during temporary fixing and the excessive sinking of the adhesive layer (X1) to the adherend can be suppressed, and the curling of the adhesive sheet during heat peeling can be suppressed, which tends to improve the workability. On the other hand, if the shear storage modulus G'(t) is 1.0×10 ⁷ Pa or less, the expansion of the thermally expandable particles makes it easier to form irregularities on the surface of the adhesive layer (X1), which tends to improve the peeling property during heat peeling. 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 even more preferably 20 to 80 μm. If the thickness of the adhesive layer (X1) at 23°C is 5 μm or more, sufficient adhesion is easily obtained, and there is a tendency to suppress unintentional peeling from the adherend during temporary fixing, positional displacement of the adherend, etc. On the other hand, if the thickness of the adhesive layer (X1) at 23°C is 150 μm or less, the peeling property during heat peeling is improved, and the curling of the adhesive sheet during heat peeling is suppressed, and there is a tendency to improve the workability. 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 a layer arbitrarily provided on the surface of the other side of the substrate (Y). The adhesive layer (X2) may be a thermal expansion layer or a non-thermal expansion layer, but is preferably a non-thermal expansion layer. By making the mechanism for reducing the adhesive force of the adhesive layer different in the adhesive layer (X1) and the adhesive layer (X2), when the adhesive force of one adhesive layer is reduced, it is possible to prevent the adhesive force of the other adhesive layer from being accidentally reduced.

When the adhesive layer (X2) is a non-thermally expandable layer, 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%, still more preferably less than 0.1%, and still more preferably less than 0.01%. Although the adhesive layer (X2) preferably 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 preferably as small as possible, and is preferably less than 3 mass%, more preferably less than 1 mass%, still more preferably less than 0.1 mass%, still more preferably less than 0.01 mass%, and still more preferably less than 0.001 mass%, relative to the total mass of the adhesive layer (X2) (100 mass%).

The adhesive layer (X2) is preferably formed of an adhesive composition (x-2) containing an adhesive resin. The following describes the components contained in the adhesive composition (x-2).

(Adhesive composition (x-2)) The adhesive composition (x-2) contains an adhesive resin and, if necessary, may also contain a crosslinking agent, an adhesive imparting agent, a polymerizable compound, a polymerization initiator, and adhesive additives generally used in adhesives other than the above components.

[Adhesive resin] As the adhesive resin, any polymer having adhesive properties alone and a mass average molecular weight (Mw) of 10,000 or more may be used. From the viewpoint of further improving the adhesive force of the adhesive layer (X2), 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 even more preferably 30,000 to 1,000,000.

As adhesive resins, for example, there can be mentioned rubber resins such as acrylic resins, urethane resins, polyisobutylene resins, polyester resins, olefin resins, silicone resins, polyvinyl ether resins, etc. 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 constituent units, the copolymer may be in the form of a block copolymer, a random copolymer, or a graft copolymer.

The adhesive composition (x-2) containing an adhesive resin is preferably an adhesive composition that is hardened by irradiation with energy rays from the viewpoint of making the mechanism of action of reducing the adhesive force different from that of the adhesive layer (X1), and more preferably, the adhesive resin is a resin having an energy ray polymerizable functional group in the side chain of the above-mentioned adhesive resin. By forming the adhesive composition, the adhesive layer (X2) can be hardened by irradiation with energy rays to become an adhesive layer with reduced adhesive force. As energy ray polymerizable functional groups, for example, (meth)acrylic acid, vinyl, allyl and the like having carbon-carbon double bonds can be listed. As energy rays, ultraviolet rays, which are easy to handle, are preferred among the above. Furthermore, the adhesive composition (x-2) may contain a monomer or prepolymer having an energy ray polymerizable functional group together with the adhesive resin having an energy ray polymerizable functional group, or in place of the adhesive resin having an energy ray polymerizable functional group. As the monomer or prepolymer having an energy ray polymerizable functional group, the same energy ray polymerizable components as those contained in the above-mentioned polymerizable composition (x-1) can be cited.

When the adhesive composition (x-2) is made into an adhesive composition that hardens by irradiation with energy rays, it is preferred that the adhesive composition further contains a photopolymerization initiator. By containing a photopolymerization initiator, the polymerization of the energy ray polymerizable component can be carried out more efficiently. As the photopolymerization initiator, the same photopolymerization initiator as that of the polymerizable composition (x-1) can be listed. The content of the photopolymerization initiator 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 total amount of the adhesive resin having an energy ray polymerizable functional group, the monomer and the prepolymer.

From the viewpoint of exhibiting excellent adhesive force, the adhesive resin preferably contains an acrylic resin. The content of the acrylic resin in the adhesive composition (x-2) is preferably 30 to 100 mass %, more preferably 50 to 100 mass %, further preferably 70 to 100 mass %, and further preferably 85 to 100 mass %, relative to the total amount (100 mass %) of the adhesive resin contained in the adhesive composition (x-2).

The content of the adhesive resin in the adhesive composition (x-2) is preferably 35 to 100 mass %, more preferably 50 to 100 mass %, further preferably 60 to 98 mass %, and further preferably 70 to 95 mass %, relative to the total amount (100 mass %) of the active ingredients in the adhesive composition (x-2).

[Crosslinking agent] In one embodiment of the present invention, when the adhesive composition (x-2) contains an adhesive resin having a functional group, it is preferred that the adhesive composition (x-2) further contains a crosslinking agent. The crosslinking agent reacts with the adhesive resin having a functional group, uses the functional group as a crosslinking starting point, and crosslinks the adhesive resins with each other.

As crosslinking agents, for example, isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents, etc. can be listed. The crosslinking agent can be used alone or in combination of two or more. Among these crosslinking agents, isocyanate crosslinking agents are preferred from the perspective of improving cohesion and adhesion and from the perspective of easy availability.

The content of the crosslinking agent is appropriately adjusted according to the number of functional groups in the adhesive resin, but 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 5 parts by mass, relative to 100 parts by mass of the adhesive resin having the functional groups.

[Adhesion-imparting agent] In one aspect of the present invention, the adhesive composition (x-2) may further contain a adhesion-imparting agent from the viewpoint of further improving the adhesion. As the adhesion-imparting agent that may be contained in the adhesive composition (x-2), the same adhesion-imparting agent as that that may be contained in the polymerizable composition (x-1) may be used.

[Adhesive additive] As the adhesive additive, the same ones as those that can be contained in the polymerizable composition (x-1) can be cited. In addition, when the adhesive composition (x-2) does not contain heat-expandable particles, since it is not necessary to avoid heat drying above the expansion starting temperature (t) of the heat-expandable particles, the adhesive composition (x-2) may contain a solvent if necessary.

The adhesive composition (x-2) can be produced by mixing an adhesive resin, a crosslinking agent if necessary, an adhesive imparting agent, an adhesive additive, and the like.

[Adhesion of adhesive layer (X2)] The adhesion of the adhesive layer (X2) on the adhesive surface is preferably 0.1 to 10.0 N/25mm, more preferably 0.2 to 8.0 N/25mm, still more preferably 0.4 to 6.0 N/25mm, and still more preferably 0.5 to 4.0 N/25mm. If the adhesion of the adhesive layer (X2) on the adhesive surface is 0.1 N/25mm or more, unintentional peeling from the adhered object during temporary fixation, positional displacement of the adhered object, etc. can be more effectively suppressed. On the other hand, if the adhesion is 10.0 N/25mm or less, the adhered object will not be damaged, and peeling becomes easy.

[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 even more 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 adhesive layer (X2) relative to the adherend. 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) of the adhesive layer (X2) at 23°C can be measured by the same method as the shear storage modulus G' of the adhesive layer (X1) at 23°C.

[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, sufficient adhesion is easily obtained, and there is a tendency to suppress unintentional peeling from the adherend during temporary fixing, positional displacement of the adherend, etc. On the other hand, if the thickness of the adhesive layer (X2) at 23°C is 150 μm or less, there is a tendency to facilitate the handling of the adhesive sheet.

<Release material> As the release material, there can be mentioned a release sheet treated with double-sided release, a release sheet treated with single-sided release, etc., and a release agent coated on a base material for the release material. As the base material for the release material, there can be mentioned plastic film, paper, etc. As the plastic film, there can be mentioned polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin, and polyethylene naphthalate resin; olefin resin films such as polypropylene resin and polyethylene resin; as the paper, there can be mentioned high-quality paper, transparent paper, kraft paper, etc.

Examples of the stripping agent include silicone-based resins, olefin-based resins, isoprene-based resins, butadiene-based resins, and other rubber-based elastomers; long-chain alkyl-based resins, alkyd-based resins, fluorine-based 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 to 200 μm, more preferably 20 to 150 μm, and even more preferably 35 to 80 μm.

[Method for producing adhesive sheet] The method for producing an adhesive sheet according to one aspect of the present invention is a method for producing an adhesive sheet, which is a method for forming an adhesive layer (X1), comprising irradiating a polymerizable composition (x-1) containing the aforementioned energy ray polymerizable component and the aforementioned thermally expandable particles with energy ray to form a polymer of the aforementioned energy ray polymerizable component. The method for forming the adhesive layer (X1) preferably comprises the following steps I and II. Step I: forming a polymerizable composition layer including a polymerizable composition (x-1) on one side of the substrate (Y) Step II: forming a polymer of the energy ray polymerizable component by irradiating the polymerizable composition layer with energy rays, and forming an adhesive layer (X1) containing the polymer and the thermally expandable particles

<Step I> If step I is a step of forming a polymerizable composition layer on the surface of one side of the substrate (Y), although it is not particularly limited, it is preferably included in the following steps I-1 to I-3. Step I-1: A step of coating a polymerizable composition (x-1) on the peeling treatment surface of the peeling material to form a polymerizable composition layer Step I-2: A step of irradiating the polymerizable composition layer with a first energy ray to prepare the energy ray polymerizable components in the polymerizable composition layer Step I-3: A step of attaching the polymerizable composition layer after the first energy ray irradiation to the substrate (Y)

(Step I-1) Step I-1 is a step of coating a polymerizable composition (x-1) on the peeling-treated surface of the peeling material to form a polymerizable composition layer. In step I-1, as a method for coating the polymerizable composition (x-1) on the peeling material, for example, spin coating, spray coating, rod coating, knife coating, roller coating, scraper coating, die coating, gravure coating, etc. can be listed.

The polymerizable composition (x-1) is preferably a solvent-free polymerizable composition as described above. When the polymerizable composition (x-1) is a solvent-free polymerizable composition, the step of heating and drying the solvent in this step does not need to be performed. On the other hand, when the polymerizable composition (x-1) contains a solvent within the range that does not violate the purpose of the present invention, after applying the polymerizable composition (x-1), heating and drying can be performed, but the heating temperature in this case becomes less than the expansion starting temperature (t) of the thermally expandable particles.

(Step I-2) Step I-2 is a step of performing a first energy ray irradiation on the polymerizable composition layer formed in step I-1 to pre-polymerize the energy ray polymerizable components in the polymerizable composition layer. The first energy ray irradiation is performed to increase the viscosity of the polymerizable composition by pre-polymerizing the energy ray polymerizable components, so as to improve the shape retention of the polymerizable composition layer. In the first energy ray irradiation, the energy ray polymerizable components are not completely polymerized and are kept in the pre-polymerization state. Thereby, the adhesion between the polymerizable composition layer and the substrate (Y) in step I-3 can be improved.

As the energy ray used for the first energy ray irradiation of step I-2, among the above, ultraviolet rays which are easy to handle are preferably used. 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 even more preferably 130 to 170 mW/cm ² . Furthermore, the light amount of the 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 even more 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 I-3) Step I-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 for example, a method of laminating the substrate (Y) on the exposed surface of the polymerizable composition layer can be cited. Although lamination can be performed while heating or without heating, it is preferably performed without heating from the perspective of suppressing the expansion of thermally expandable particles. At this time, the polymerizable composition layer that has been pre-polymerized by the first energy ray irradiation has good adhesion to the substrate (Y) even without heating.

<Step II> Step II is a step of irradiating the polymerizable composition layer formed in step I with energy rays to form a polymer of the energy ray polymerizable component, and forming an adhesive layer (X1) containing the polymer and thermally expandable particles.

Here, when the first energy ray irradiation is performed in step I, the energy ray irradiation in step II becomes the second energy ray irradiation performed on the polymerizable composition layer after pre-polymerization. The energy ray irradiation in step II is preferably different from the first energy ray irradiation, and even if the energy ray is irradiated, it is substantially performed to the extent that the polymerization of the energy ray polymerizable component cannot be performed. By the energy ray irradiation in step II, 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 II, among the above, ultraviolet rays are preferably used because they are easy to handle. The illuminance of the ultraviolet rays in the energy ray irradiation of step II is preferably 100 to 350 mW/cm ² , more preferably 150 to 300 mW/cm ² , and even more preferably 180 to 250 mW/cm ² . The amount of ultraviolet rays in the energy ray irradiation of step II is preferably 500 to 4,000 mJ/cm ² , more preferably 1,000 to 3,000 mJ/cm ² , and even more preferably 1,500 to 2,500 mJ/cm ² . The energy ray irradiation of step II 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.

Furthermore, when step I includes the above steps I-1 to I-3, the polymerizable composition layer is obtained as an intermediate layer of a laminated body in which a release material, a polymerizable composition layer, and a substrate (Y) are laminated in this order. At this time, the second energy ray irradiation may be performed on the laminated body having such a structure. In this case, from the viewpoint that it is 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 release material and the substrate (Y) is selected to be energy ray-transmissive.

In any of the steps I and II above, from the viewpoint of suppressing the expansion of the heat-expandable particles, it is preferred that the step of heating the polymerizable composition is not included. In addition, the so-called "heating" here means, for example, intentional heating during drying and lamination, and does not include the temperature rise caused by heat given to the polymerizable composition by energy ray irradiation, polymerization heat generated by polymerization of the polymerizable composition by energy ray, etc. When it is necessary to include a step of heating the polymerizable composition, the heating temperature is preferably "a temperature lower than the expansion starting temperature (t)", more preferably "expansion starting temperature (t) - 5°C" or lower, further preferably "expansion starting temperature (t) - 10°C" or lower, and further preferably "expansion starting temperature (t) - 15°C" or lower. Furthermore, when the temperature of the polymerizable composition is accidentally increased, it is preferred that the polymerizable composition be cooled so that the temperature becomes within the above temperature range.

When the adhesive sheet of one aspect of the present invention has the structure of the double-sided adhesive sheet, the manufacturing method of the adhesive sheet of one aspect of the present invention preferably further includes the following step III.

<Step III> Step III: Forming an adhesive layer (X2) on the other side of the substrate (Y)

The method for forming the adhesive layer (X2) can be appropriately determined according to the type of composition constituting the adhesive layer (X2). For example, when the adhesive layer (X2) is formed using the adhesive composition (x-2), step III preferably includes the following steps III-1 and III-2. Step III-1: Applying the adhesive composition (x-2) on one side of the peeling material to form the adhesive layer (X2) Step III-2: Attaching the adhesive layer (X2) formed in step III-1 to the other side of the substrate (Y)

As a method for applying the adhesive composition (x-2) in step III-1, the same method as the method for applying the polymerizable composition (x-1) in step I-1 can be listed. In addition, when the adhesive layer (X2) contains a solvent, it can include a step of drying the coating film after applying the adhesive composition (x-2). As mentioned above, the peeling material used in step III-1 and the peeling material used in step I-1 are preferably designed in a manner with different peeling forces from the viewpoint of suppressing the phenomenon that the adhesive layer is peeled off due to the separation of the two peeling materials.

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

[Application and use of adhesive sheet] An adhesive sheet of one aspect of the present invention has sufficient adhesive force when temporarily fixed, but can also be peeled off by heating at low temperature, so it can be applied to various applications. Specifically, it is suitable for use as a dicing sheet used when cutting a target object such as a semiconductor wafer, a back grinding sheet used in the step of grinding a target object, an expansion tape used to expand the distance between targets of semiconductor chips singulated by dicing, a transfer tape used to reverse the front and back sides of a target object such as a semiconductor chip, a temporary fixing sheet used to temporarily fix the inspection object, etc.

Although not particularly limited, the adherend of the adhesive sheet of one aspect of the present invention may include semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, sapphire substrates, display panels, and substrates for panels. Since the adhesive sheet of one aspect of the present invention can be peeled off by heating at low temperatures, it is suitable for temporarily fixing an adherend that is easily changed by heat, such as a semiconductor chip with a DAF.

The heating temperature when the adhesive sheet of one aspect of the present invention is heated and peeled off from the adhered body is above the expansion starting temperature (t) of the heat-expandable particles, preferably "a temperature higher than the expansion starting temperature (t)", more preferably "expansion starting temperature (t) + 2°C" or above, more preferably "expansion starting temperature (t) + 4°C" or above, and even more preferably "expansion starting temperature (t) + 5°C" or above. In addition, from the perspective of energy saving and suppressing the thermal changes of the adhered body during heat peeling, it is preferably "expansion starting temperature (t) + 50°C" or below, more preferably "expansion starting temperature (t) + 40°C" or below, and even more preferably "expansion starting temperature (t) + 20°C" or below. Furthermore, from the viewpoint of suppressing thermal changes in the adhered body, the heating temperature during heat peeling is preferably 120°C or less, more preferably 115°C or less, further preferably 110°C or less, and further preferably 105°C or less, within the range above the expansion starting temperature (t).

The heating method is not particularly limited as long as it can heat to a temperature above the expansion temperature of the thermally expandable particles. For example, electric heaters, dielectric heating, magnetic heating, infrared heating such as near infrared, mid infrared, and far infrared, etc., heating by electromagnetic waves, etc. can be appropriately used. In addition, the heating method can be any of a contact heating method such as a heating roller and a heating press, and a non-contact heating method such as an environmental heating device and infrared irradiation.

[Manufacturing method of semiconductor device] The present invention also provides a manufacturing method of a semiconductor device using an adhesive sheet of one embodiment of the present invention. As one embodiment of the manufacturing method of a semiconductor device of the present invention, there can be cited an embodiment in which the adhesive sheet of one embodiment of the present invention is used as a temporary fixing sheet for processing an adherend (hereinafter also referred to as "the manufacturing method of a semiconductor device of the first embodiment").

<Method for manufacturing semiconductor device of the first aspect> As a more specific aspect of the method for manufacturing semiconductor device of the first aspect, a method for manufacturing semiconductor device can be cited, which includes attaching an adhesive sheet of one aspect of the present invention to a processing object, and performing one or more treatments selected from grinding treatment and singulation treatment (hereinafter also referred to as "processing treatment") on the processing object, and after performing the treatment, heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C to expand the adhesive layer (X1). In this specification, the so-called "semiconductor device" refers to a general device that can perform functions by utilizing semiconductor characteristics. For example, there may be listed a wafer having an integrated circuit, a thinned wafer having an integrated circuit, a chip having an integrated circuit, a thinned chip having an integrated circuit, an electronic component including such a chip, and an electronic device having such an electronic component.

In the first embodiment of the method for manufacturing a semiconductor device, the adhesive layer of the adhesive sheet to which the processing object is attached can be an adhesive layer (X1), and when the adhesive sheet is a double-sided adhesive sheet, it can be an adhesive layer (X2). When the adhesive sheet is a double-sided adhesive sheet, it is preferred to attach the processing object to the adhesive layer on one side and to attach the support body to the adhesive layer on the other side. By fixing the processing object to the support body through the adhesive sheet, vibration, positional deviation, and damage to the fragile processing object can be suppressed during processing, and processing accuracy and processing speed can be improved. At this time, the support may be attached to the adhesive layer (X1) and the object to be processed may be attached to the adhesive layer (X2), or the object to be processed may be attached to the adhesive layer (X1) and the support may be attached to the adhesive layer (X2). In the case where the support is attached to the adhesive layer (X1) and the object to be processed is attached to the adhesive layer (X2), since the support is attached to the adhesive layer (X1) having excellent releasability after heat treatment, even if the support is made of a hard material, heat peeling can be performed without bending the adhesive sheet and the support. Furthermore, the adhesive layer (X2) can be appropriately composed according to the type of the object to be processed. For example, when the adhesive layer (X2) is irradiated with energy rays to reduce the adhesive force, the object to be processed can be peeled off without contaminating the object by using the residues derived from the thermally expandable particles. On the other hand, when the object to be processed is attached to the adhesive layer (X1) and the support is attached to the adhesive layer (X2), the object to be processed is attached to the adhesive layer (X1) having excellent releasability after heat treatment. When heat peeling is performed after processing, the object to be processed can be peeled off from the adhesive sheet by self-peeling, thereby reducing damage to the object to be processed.

When a double-sided adhesive sheet is used as one embodiment of the present invention, the manufacturing method of the semiconductor device of the first embodiment is preferably a manufacturing method including the following steps 1A to 5A (hereinafter also referred to as "manufacturing method A"). Step 1A: a step of attaching a processing object to the adhesive layer (X2) of the adhesive sheet and attaching a support body to the adhesive layer (X1) Step 2A: a step of performing one or more treatments selected from grinding treatment and singulation treatment on the aforementioned processing object Step 3A: a step of attaching a thermosetting film to the surface opposite to the adhesive layer (X2) of the processing object to which the aforementioned treatment is applied Step 4A: a step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C, and separating the adhesive layer (X1) from the aforementioned support body Step 5A: a step of separating the adhesive layer (X2) from the aforementioned processing object

Hereinafter, a method for manufacturing a semiconductor device including steps 1A to 5A will be described with reference to the drawings. In the following description, although the example of using a semiconductor wafer as a processing object is mainly described, the same is true for other processing objects.

(Step 1A) Step 1A is a step of attaching an object to be processed to the adhesive layer (X2) of the adhesive sheet, and attaching a support to the adhesive layer (X1). Figure 3 is a cross-sectional view showing the step of attaching a semiconductor wafer W to the adhesive layer (X2) of the adhesive sheet 2a, and attaching a support 3 to the adhesive layer (X1). The semiconductor wafer W is attached in such a way that the surface W1, which is the surface of the electrical path, becomes the side of the adhesive layer (X2). The semiconductor wafer W may be a silicon wafer, or may be a wafer of gallium arsenide, silicon carbide, sapphire, lithium tantalum, lithium niobate, gallium nitride, indium phosphide, etc., or a glass wafer. The thickness of the semiconductor wafer W before grinding is usually 500 to 1000 μm. The circuit on the surface W1 of the semiconductor wafer W can be formed by conventional methods such as etching and lift-off.

The material of the support 3 can be appropriately selected according to the type of the object to be processed, the processing content, etc., taking into account the required characteristics such as mechanical strength and heat resistance. As the material of the support 3, for example, 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; composite materials such as glass epoxy resin, etc., among which SUS, glass, and silicon wafers are preferred. As the above-mentioned engineering plastics, for example, nylon, polycarbonate (PC), polyethylene terephthalate (PET), etc. can be listed. Examples of the super engineering plastics include polyphenylene sulfide (PPS), polyether sulfide (PES), and polyether ether ketone (PEEK).

The support 3 is preferably attached to the entire adhesive surface of the adhesive layer (X1). Therefore, the surface area of the support 3 attached to the adhesive surface side 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 3 attached to the adhesive surface side of the adhesive layer (X1) is preferably flat. The shape of the support 3 is not particularly limited, but is preferably plate-shaped. The thickness of the support 3 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 2A) Step 2A is a step of performing one or more processes selected from grinding and singulation on the aforementioned processing object. As one or more processes selected from grinding and singulation, for example, grinding using a grinder, etc., singulation by blade dicing, laser dicing, invisible dicing (registered trademark) method, knife tip dicing, invisible tip dicing, etc. can be listed. Among these, singulation by invisible dicing, grinding and singulation by knife tip dicing, grinding and singulation by invisible tip dicing are suitable, and grinding and singulation by knife tip dicing, grinding and singulation by invisible tip dicing are more suitable.

The invisible dicing method is a method of singulating semiconductor wafers by forming a modified region inside the semiconductor wafer through irradiation with laser light, and using the modified region as the starting point for division. The modified region formed in the semiconductor wafer is a portion that has become brittle due to multi-photon absorption, and is singulated into semiconductor chips by applying stress to the semiconductor wafer in a direction parallel to the wafer surface and in which the wafer expands, using the modified region as the starting point, and extending toward the surface and back of the semiconductor wafer. That is, the modified region is formed along the dividing line during singulation. The modified region is formed inside the semiconductor wafer by irradiation with laser light with a matching focus. 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 tip dicing method is also called the DBG method (Dicing Before Grinding). The blade tip dicing method is a method of thinning and singulating the semiconductor wafer by forming grooves in advance along the predetermined dividing line at a depth shallower than its thickness, and then grinding the back of the semiconductor wafer until the grooves at least reach the grinding surface. The grooves reaching the grinding surface become incisions that pass through the semiconductor wafer, and the semiconductor wafer is divided and singulated into semiconductor chips by the incisions. The pre-formed grooves are usually provided on the surface (conductor surface) of the semiconductor wafer, and can be formed by cutting using, for example, a wafer cutting device equipped with a conventionally known cutting blade.

Stealth Dicing Before Grinding (SDBG) is also called Stealth Dicing Before Grinding (SDBG). Stealth Dicing Before Grinding is the same as Stealth Dicing. Although it is a method of singulating semiconductor wafers by forming a modified region inside the semiconductor wafer through irradiation of laser light, the modified region is used as the starting point for division, but the point of performing grinding to thin the semiconductor wafer and singulate the semiconductor wafer into semiconductor chips is different from the Stealth Dicing. Specifically, the semiconductor wafer with the modified region is ground on the back and thinned. At this time, by applying pressure to the semiconductor wafer, the modified region is used as the starting point, and the cracks are extended toward the bonding surface of the adhesive layer of the semiconductor wafer, so that the semiconductor wafer is singulated into semiconductor chips. Although the grinding thickness after forming the modified area can be the thickness reaching the modified area, even if it is not possible to grind strictly to reach the modified area, it can be ground to a position close to the modified area and cut off by the processing pressure of the grinding stone.

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

FIG4 is a cross-sectional view showing the step of forming a plurality of modified regions 5 using a laser light irradiation device 4 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 5 at approximately equal intervals inside the semiconductor wafer W.

FIG5 is a cross-sectional view showing the steps of grinding the back side W2 of the semiconductor wafer W forming the modified region 5 by a grinder 6, thinning the semiconductor wafer W by cutting with the modified region 5 as a starting point, and singulating into a plurality of semiconductor chips CP. The semiconductor wafer W forming the modified region 5 is ground with the support 3 supporting the semiconductor wafer W fixed on a fixed table such as a chuck seat.

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 singulation are performed by stealth tip dicing, it is easy to set the thickness of the semiconductor chip CP obtained by grinding to 50 μm or less, more preferably 10 to 45 μm. The size of the semiconductor chip CP after grinding in a plan view is preferably less than 600 mm ² , more preferably less than 400 mm ² , and even more preferably less than 300 mm ^2. Here, the so-called plan view refers to observation along the thickness direction. The shape of the semiconductor chip CP after singulation in a plan view may be square or may be an elongated shape such as a rectangle.

(Step 3A) Step 3A is 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) of the object to be processed as described above. FIG. 6 is a cross-sectional view showing a step of attaching a thermosetting film 7 having a support sheet 8 to the surface of the plurality of semiconductor chips CP obtained by the above-mentioned processing on the opposite side of the adhesive layer (X2).

The thermosetting film 7 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 7 may contain a curing agent for the above-mentioned thermosetting resin, a thermoplastic resin, an inorganic filler, a curing accelerator, etc., if necessary. As the thermosetting film 7, for example, a thermosetting film generally used as a die bonding film, a die bonding film, etc. can be used. Although the thickness of the thermosetting film 7 is not particularly limited, it is usually 1 to 200 μm, preferably 3 to 100 μm, and more preferably 5 to 50 μm. The supporting sheet 8 can be any material that can support the thermosetting film 7, for example, the resin, metal, paper material, etc. listed as the base material (Y) of the adhesive sheet of one embodiment of the present invention.

As a method of attaching the thermosetting film 7 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. From the viewpoint of suppressing the expansion of the thermally expansive particles and suppressing the thermal changes of the adherend, the heating temperature when performing the lamination while heating is preferably "a temperature lower than the expansion start temperature (t)", more preferably "the expansion start temperature (t) - 5°C" or less, more preferably "the expansion start temperature (t) - 10°C" or less, and even more preferably "the expansion start temperature (t) - 15°C" or less.

(Step 4A) Step 4A is a step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C to separate the adhesive layer (X1) from the aforementioned support. FIG. 7 is a cross-sectional view illustrating the step of heating the adhesive sheet 2a to separate the adhesive layer (X1) from the support 3.

The heating temperature in step 4A is above the expansion starting temperature (t) of the heat-expandable particles and is within the range of 120°C or below, preferably "a temperature higher than the expansion starting temperature (t)", more preferably "the expansion starting temperature (t) + 2°C" or above, even more preferably "the expansion starting temperature (t) + 4°C" or above, and even more preferably "the expansion starting temperature (t) + 5°C" or above. Furthermore, from the perspective of energy saving and suppressing the thermal change of the adhered body during heat peeling, the heating temperature in step 4A is preferably below "expansion starting temperature (t) + 50°C" in the range below 120°C, more preferably below "expansion starting temperature (t) + 40°C", and even more preferably below "expansion starting temperature (t) + 20°C". From the perspective of suppressing the thermal change of the adhered body, the heating temperature in step 4A is preferably below 115°C, more preferably below 110°C, and even more preferably below 105°C in the range above the expansion starting temperature (t).

(Step 5A) Step 5A is a step of separating the adhesive layer (X2) from the aforementioned processing object. FIG. 8 is a cross-sectional view showing the step of separating the adhesive layer (X2) from a plurality of semiconductor chips CP. The method of separating the adhesive layer (X2) from a plurality of semiconductor chips CP can be appropriately selected according to the type of the adhesive layer (X2). For example, when the adhesive layer (X2) is an adhesive layer whose adhesive force is reduced by energy beam irradiation, the adhesive layer (X2) is irradiated with energy beams to reduce the adhesive force and then the separation can be performed.

Through the above steps 1A to 5A, a plurality of semiconductor chips CP attached to the thermosetting film 7 are obtained. Then, it is preferred to divide the thermosetting film 7 to which the plurality of semiconductor chips CP are attached into the same shape as the semiconductor chip CP to obtain a semiconductor chip CP with a thermosetting film 7. As a method for dividing the thermosetting film 7, for example, a method such as laser cutting, expansion, and dissolution by laser light can be applied. FIG. 9 shows a semiconductor chip CP with a thermosetting film 7 divided into the same shape as the semiconductor chip CP.

The semiconductor chip CP with the thermosetting film 7 is attached to the substrate from the thermosetting film 7 side (die bonding) after appropriately performing an expansion step of expanding the interval between the semiconductor chips CP, a rearrangement step of arranging the plurality of semiconductor chips CP with the expanded interval, and a reversal step of reversing the front and back sides of the plurality of semiconductor chips CP, if necessary. Then, the semiconductor chip and the substrate can be fixed by thermally curing the thermosetting film.

The manufacturing method of one aspect of the present invention may be a method A that does not include step 3A. When step 3A is not included, the method may include the following step 4A' instead of step 4A. Step 4A': heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) to separate the adhesive layer (X1) from the aforementioned support

When a double-sided adhesive sheet is used as one aspect of the present invention, the manufacturing method of the semiconductor device of the first aspect may be a manufacturing method including the following steps 1B to 4B (hereinafter also referred to as "manufacturing method B"). Step 1B: a step of attaching a processing object to the adhesive layer (X1) of the adhesive sheet, and attaching a support to the adhesive layer (X2) of the aforementioned adhesive sheet Step 2B: a step of performing one or more treatments selected from grinding treatment and singulation treatment on the aforementioned processing object Step 3B: a step of attaching a thermosetting film having thermosetting properties to the surface opposite to the aforementioned adhesive layer (X1) of the processing object to which the aforementioned treatment is applied Step 4B: a step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C, and separating the adhesive layer (X1) from the aforementioned processing object

Steps 1B to 3B are described by replacing the adhesive layer (X1) described in steps 1A to 3A with the adhesive layer (X2), and by replacing the adhesive layer (X2) with the adhesive layer (X1).

Step 4B is a step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C to separate the adhesive layer (X1) and the aforementioned processing object. The heating conditions such as the heating temperature of the adhesive sheet in step 4B are the same as those described in step 4A. Through step 4B, a plurality of semiconductor chips attached to the thermosetting film are obtained. Then, the thermosetting film is divided in the same manner as in the above-mentioned manufacturing method A to obtain a semiconductor chip with a thermosetting film.

The manufacturing method B may include a step 5B of separating the adhesive layer (X2) from the aforementioned support after step 4B. The method of separating the adhesive layer (X2) from the support may be appropriately selected according to the type of the adhesive layer (X2). For example, when the adhesive layer (X2) is an adhesive layer whose adhesive force is reduced by energy ray irradiation, the adhesive layer (X2) may be irradiated with energy ray to reduce the adhesive force and then separated.

The manufacturing method of one aspect of the present invention may be a manufacturing method B that does not include step 3B. When step 3B is not included, the manufacturing method may include the following step 4B' instead of step 4B. Step 4B': heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) to separate the adhesive layer (X1) from the aforementioned processing object

<Other aspects of the method for manufacturing a semiconductor device> The method for manufacturing a semiconductor device of the present invention is not limited to the method for manufacturing a semiconductor device of the first aspect described above, and may be a method for manufacturing a semiconductor device of other aspects different from the first aspect. As an example of another aspect of the method for manufacturing a semiconductor device, there can be cited a method in which an adhesive sheet of one aspect of the present invention is used as a temporary fixing sheet for inspecting an inspection object as one of the manufacturing steps. As inspections of the inspection object, for example, optical microscopes, defect inspections using lasers (e.g., garbage inspections, surface scratch inspections, wiring pattern inspections, etc.), and surface inspections by visual inspections can be cited. As inspection objects, for example, semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, LED components, sapphire substrates, displays, panel substrates, etc. can be listed. When an adhesive sheet of one aspect of the present invention is used as a temporary fixing sheet for inspecting inspection objects, the inspection can be carried out in a state where a plurality of inspection objects are attached to the adhesive layer (X1) of the adhesive sheet. After the inspection, for example, a portion of the adhesive layer (X1) to which the plurality of inspection objects are attached can be locally heated to selectively heat and peel off a specific inspection object attached to the portion. At this time, since the adhesive sheet of one aspect of the present invention can be thermally peeled at a low temperature, even if the thermal peeling operation is excellent in workability and energy saving, and the inspection object is susceptible to thermal changes, the thermal changes of the inspection object caused by heating during thermal peeling can be suppressed.

As another example of a method for manufacturing a semiconductor device of another aspect, a method for separating a processing object attached to another sheet from the other sheet using an adhesive sheet of one aspect of the present invention can be cited. For example, although a plurality of semiconductor chips spaced apart on an expansion tape are attached to the adhesive surface of the expansion tape, the operation of selecting such chips one by one is complicated. In the method for manufacturing a semiconductor device according to one aspect of the present invention, an adhesive layer (X1) of an adhesive sheet according to one aspect of the present invention is attached to the exposed surface of a plurality of semiconductor chips attached to an expansion tape, and then the expansion tape is peeled off from the plurality of semiconductor chips, so that the plurality of semiconductor chips can be separated from the expansion tape at one time. Through the above steps, a plurality of semiconductor chips attached to an adhesive sheet according to one aspect of the present invention are obtained. The plurality of semiconductor chips can then be easily separated by heating the adhesive layer (X1) to a temperature above the expansion starting temperature (t) of the thermally expandable particles. At this time, since the adhesive sheet of one aspect of the present invention can be thermally peeled at low temperature, the workability and energy saving of the thermal peeling operation are excellent, and the thermal change of the adherend caused by heating during thermal peeling can be suppressed even if the adherend is susceptible to thermal change. The separated multiple semiconductor chips can be transferred to other adhesive sheets, and once separated, they can be used for the re-arrangement step of arranging multiple semiconductor chips. [Example]

Although the following embodiments are described in more detail with respect to the present invention, the present invention is not limited to the following embodiments. In the following description, the so-called "non-expandable adhesive layer (X1')" means an adhesive layer that does not contain thermally expandable particles, and an adhesive layer that does not contain thermally expandable particles in an adhesive sheet prepared in a comparative example described later and an adhesive layer prepared for the measurement of shear storage modulus G' are equivalent to a non-expandable adhesive layer (X1'). The physical property values in the following synthesis examples and embodiments are values measured by the following method.

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

[Thickness of each layer] Measured using a constant pressure thickness tester manufactured by Teclock Co., Ltd. (model: "PG-02J", standard specification: in accordance with 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., Master Sizer 3000 manufactured by Malvern). The particle sizes corresponding to 50% and 90% of the cumulative volume frequencies calculated from the smaller particle size of 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 elasticity E’ of substrate (Y)] A substrate (Y) cut into 5 mm in length and 30 mm in width was used as a test sample. A dynamic viscoelasticity measuring device (manufactured by TA Instruments, product name “DMAQ800”) was used to measure the storage elasticity E’ at a specified temperature under the following conditions: test start temperature 0°C, test end temperature 200°C, heating rate 3°C/min, vibration frequency 1 Hz, amplitude 20μm.

[Shear storage modulus G'(23) of adhesive layer (X1) at 23°C] The adhesive layer (X1) was set to 8mm in diameter × 3mm in thickness 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) was prepared as a sample for measuring the shear storage modulus of the adhesive layer (X1) corresponding to each embodiment, except that the thermally expansive particles were not contained, and the shear storage modulus G’ was measured. In addition, the shear storage modulus G' of the non-expandable adhesive layer (X1') prepared in the comparative example was also measured by this evaluation method. The non-expandable adhesive layer (X1') was set to a diameter of 8 mm × a thickness of 3 mm as a test sample, and a viscoelasticity measuring device (manufactured by Anton Paar, device name "MCR300") was used. Under the conditions of test start temperature 0°C, test end temperature 300°C, temperature rise rate 3°C/min, and vibration frequency 1 Hz, the shear storage modulus G'(23) at 23°C and the shear storage modulus G'(t) at the expansion start temperature (t) of the thermally expandable particles were measured by the torsional shear method. The expansion starting temperature (t) of the heat-expandable particles of the non-expandable adhesive layer (X1'), which is the sample for measuring the shear storage elasticity, refers to the expansion starting temperature (t) of the heat-expandable particles contained in the adhesive layer (X1) of the embodiment corresponding to the sample for measuring the shear storage elasticity, which is 88°C as described later in this embodiment. In addition, since the adhesive sheet prepared in the comparative example does not have an expansion starting temperature (t), the shear storage elasticity G' is measured at 88°C in the same manner as in the embodiment.

Synthesis Example 1 (Synthesis of Urethane Acrylate Prepolymer) A reaction product was obtained by mixing 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, and stirring at 80°C for 6 hours. When the IR spectrum of the obtained reaction product was measured by infrared spectroscopy, it was confirmed that the isocyanate group almost disappeared. Then, 1 part by mass of 2-isocyanate ethyl acrylate was mixed with the entire amount of the obtained reaction product, and stirred at 80°C for 3 hours to obtain a urethane acrylate prepolymer. When the IR spectrum of the obtained urethane acrylate prepolymer was measured by infrared spectroscopy, it was confirmed that the isocyanate group almost disappeared. The mass average molecular weight (Mw) of the obtained urethane acrylate prepolymer was 25,000.

Examples 1 to 22 (Preparation of polymerizable composition) The components listed in Table 1 were mixed in the blending composition listed in Table 1 to obtain a solvent-free polymerizable composition. The details of the components 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: isocyanuric acid ethylene oxide modified triacrylate (component (a1-4)) [Multifunctional (meth)acrylate prepolymer] Urethane acrylate prepolymer: prepared in Synthesis Example 1 (component (a2)) Polyacryl acrylate prepolymer: "KANEKA XMAP (Registered trademark) RC100C" (manufactured by Zhongyuan Chemical Industry Co., Ltd., polyacrylic acid-based prepolymer having acryl groups at both ends, mass average molecular weight (Mw): 21,500) (component (a2)) [Photopolymerization initiator] 1-Hydroxycyclohexyl phenyl ketone [Thermal expansion particles] manufactured by AkzoNobel, product name "Expancel (Registered trademark) 031-40" (DU type), expansion starting temperature (t) = 88°C, average particle size (D ₅₀ ) = 12.6 μm, 90% particle size (D ₉₀ ) = 26.2 μm In addition, "-" in "Composition of adhesive layer (X1) or non-expandable adhesive layer (X1')" in Table 1 means that the component is not mixed.

(Production of Adhesive Sheet) Using the solvent-free polymerizable composition produced above, an adhesive sheet was produced in the following order. 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-PET381031", thickness: 38 μm) to form a polymerizable composition layer. The polymerizable composition layer was irradiated with ultraviolet light under the conditions of an illumination of 150 mW/cm ² and a light quantity of 100 mJ/cm ² to perform preliminary polymerization. In addition, the thickness of the polymerizable composition layer was adjusted so that the thickness of the obtained adhesive layer (X1) would be the thickness described in Table 1. 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, thereby obtaining a laminated body in which a release film, a polymerizable composition layer, and a substrate (Y) were laminated in this order. The storage elastic modulus E'(23) of the substrate (Y) at 23°C was 3.0×10 ⁹ Pa, and the storage elastic 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 under the conditions of illuminance of 200 mW/cm ² and light quantity of 2,000 mJ/cm ² (irradiation 4 times at 500 mJ/cm ² ) to form an adhesive layer (X1), and an adhesive sheet having the release film, adhesive layer (X1) and substrate (Y) laminated in this order was obtained. The illuminance and light quantity during ultraviolet irradiation are values measured using an illuminance and light quantity meter (manufactured by EIT, product name "UV Power Puck II").

Comparative Examples 1 to 5 Except that the composition of the adhesive layer (X1) in Example 1 is changed to the composition described in Table 1, the other steps are the same as Example 1 to obtain an adhesive sheet in which a release film, a non-expandable adhesive layer (X1') and a substrate (Y) are laminated in this order.

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

[Measurement of Adhesive Strength at 23°C Before Thermal Expansion of Adhesive Layer (X1)] The peeling film was removed from the adhesive layer (X1) cut into adhesive sheets of 25 mm × 250 mm, and the exposed surface of the adhesive layer (X1) was bonded to the mirror surface of a silicon mirror wafer using a 2 kg rubber roller in accordance with JIS Z0237:2000, and then left to stand for 20 minutes in an environment of 23°C and 50% RH (relative humidity). After standing under the above conditions, the adhesion was measured at a tension speed of 300 mm/min using a tensile tester (manufactured by A&D Co., Ltd., product name "Tensilon (registered trademark)") in an environment of 23°C and 50% RH (relative humidity) according to JIS Z0237:2000 by a 180° peel method.

[Measurement of Adhesive Strength at 23°C after Thermal Expansion of Adhesive Layer (X1)] The above test sample was placed on a hot plate in such a manner that the silicon mirror wafer was in contact with the hot plate and the adhesive sheet side was not in contact with the hot plate. It was heated at 100°C, which is above the expansion starting 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 according to JIS Z0237:2000. In order to prevent the adhesive force from being accidentally peeled off when the adhesive sheet is fixed and the adhesive force measurement is difficult, 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, and the exposed surface of the adhesive layer (X1) was placed on the mirror surface of the silicon mirror wafer using a 2kg rubber roller according to JIS Z0237:2000. The samples were then placed in an environment of 23℃ and 50%RH (relative humidity) for 20 minutes to serve as test samples. Next, the test sample is placed on the hot plate in such a way that the silicon mirror wafer is in contact with the hot plate and the adhesive sheet is not in contact with the hot plate, and heated at a maximum temperature of 100°C, which is above the expansion starting temperature of the thermally expandable particles, for 60 seconds. The ratio (%) of the peeled area of the adhesive sheet at the time of heating for 60 seconds (peeled area × 100/the total area of the adhesive sheet) is calculated and evaluated according to the following criteria. A: The adhesive sheet is completely peeled within 60 seconds. B: After heating for 60 seconds, the peeled area is 30% or more and less than 100%. C: After heating for 60 seconds, the peeled area is less than 30%. In addition, for those rated "A", the time (seconds) required for complete peeling is measured.

[Method for measuring the adhesion and self-peeling properties of the non-expandable adhesive layer (X1’) at 23°C] The adhesion and self-peeling properties of the non-expandable adhesive layer (X1’) prepared in Comparative Examples 1 to 5 were measured by replacing the adhesive layer (X1) described in the method for measuring the adhesion and self-peeling properties of the adhesive layer (X1) at 23°C with the non-expandable adhesive layer (X1’). However, the so-called “before thermal expansion” and “after thermal expansion” in the “adhesion of the non-expandable adhesive layer (X1’) at 23°C” in Table 2 refer to “before the heat treatment equivalent to the heat expansion treatment of the embodiment” and “after the heat treatment equivalent to the heat expansion treatment of the embodiment” in Comparative Examples 1 to 5, and the so-called “heat treatment equivalent to the heat expansion treatment of the embodiment” refers to the heat treatment recorded in [Measurement of the adhesion of the adhesive layer (X1) at 23°C after thermal expansion].

From Table 2, it is understood that the adhesive sheets of Examples 1 to 22 can be peeled off by heating at a low temperature (100°C) even though they all have sufficient adhesive force before heat peeling. In addition, it is understood 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). On the other hand, the adhesive sheets of Comparative Examples 1 to 5 cannot be peeled off by heating.

1a, 1b, 2a, 2b: Adhesive sheet 10, 10a, 10b: Stripping material 3: Support 4: Laser irradiation device 5: Modified area 6: Grinding machine 7: Thermosetting film 8: Support sheet W: Semiconductor wafer W1: Surface of semiconductor wafer and semiconductor chip W2: Back of semiconductor wafer and semiconductor chip CP: Semiconductor chip

[FIG. 1] is a cross-sectional view showing an example of the structure of the adhesive sheet of the present invention. [FIG. 2] is a cross-sectional view showing an example of the structure of the adhesive sheet of the present invention. [FIG. 3] is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 4] is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 5] is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 6] is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [FIG. 7] is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [Figure 8] is a cross-sectional view illustrating an example of the steps of the method for manufacturing a semiconductor device of the present invention. [Figure 9] is 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

10: Peeling material

(X1): Adhesive layer

(Y): Base material

Claims (15)

A method for manufacturing an adhesive sheet, comprising a substrate (Y), an adhesive layer (X1) containing a polymer having an energy ray polymerizable component and thermally expandable particles having an expansion starting temperature (t) of 50 to 110°C, wherein the method for forming the adhesive layer (X1) comprises the step of irradiating a polymerizable composition containing the energy ray polymerizable component and the thermally expandable particles with energy ray to form the polymer having the energy ray polymerizable component, and wherein the shear storage modulus G'(23) of the adhesive layer (X1) at 23°C is 4.3×10 ⁵ to 5.0×10 ⁷ Pa is used for attaching an adhesive sheet to a processing object, and performing one or more treatments selected from a grinding treatment and a singulation treatment on the processing object. After the treatment, the adhesive sheet is heated to a temperature above the expansion starting temperature (t) and below 120°C to expand the adhesive layer (X1). The method for manufacturing an adhesive sheet as described in claim 1, 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). A method for manufacturing an adhesive sheet as described in claim 1 or 2, wherein the thickness of the adhesive layer (X1) at 23°C is 5 to 150 μm. A method for manufacturing an adhesive sheet as described in claim 1 or 2, wherein the adhesive force of the adhesive layer (X1) at 23°C before thermal expansion is 0.1~12.0N/25mm. A method for manufacturing an adhesive sheet as described in claim 1 or 2, wherein the average particle size of the thermally expandable particles at 23°C is 1 to 30 μm. The method for manufacturing an adhesive sheet as described in claim 1 or 2 comprises a substrate (Y), an adhesive layer (X1) disposed on a surface of one side of the substrate (Y), and an adhesive layer (X2) disposed on a surface of the other side of the substrate (Y). A method for manufacturing an adhesive sheet as described in claim 6, wherein the adhesive layer (X2) is hardened by irradiating energy rays to reduce the adhesive force. The manufacturing method of the adhesive sheet as described in claim 1 or 2 includes a step of heating the aforementioned adhesive sheet to a temperature above the expansion starting temperature (t) and below 120°C to expand the adhesive layer (X1), and the method of heating the adhesive layer (X1) includes a contact heating method or a non-contact heating method using an environmental heating device. The method for manufacturing an adhesive sheet as described in claim 1 or 2, wherein the method for forming the aforementioned adhesive layer (X1) comprises the following steps I and II, step I: forming a polymerizable composition layer comprising the aforementioned polymerizable composition on the surface side of one side of the substrate (Y); step II: forming a polymer of the aforementioned 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. A method for manufacturing an adhesive sheet as described in claim 1 or 2, wherein the aforementioned polymerizable composition does not contain a solvent. The method for manufacturing the adhesive sheet as described in claim 1 or 2 does not include the step of heating the aforementioned polymeric composition. A method for manufacturing a semiconductor device, comprising: attaching an object to be processed to an adhesive sheet manufactured by the method for manufacturing an adhesive sheet as described in claim 1 or 2, subjecting the object to one or more treatments selected from a grinding treatment and a singulation treatment, and after the aforementioned treatments, heating the adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C to expand the adhesive layer (X1). A method for manufacturing a semiconductor device comprises the following steps 1A to 5A: Step 1A: attaching a processing object to an adhesive layer (X2) of an adhesive sheet manufactured by the method for manufacturing an adhesive sheet as described in claim 6, and attaching a support to the adhesive layer (X1) of the adhesive sheet; Step 2A: performing one or more of a grinding process and a singulation process on the processing object; Treatment steps Step 3A: A step of attaching a thermosetting film having thermosetting properties to the surface of the aforementioned adhesive layer (X2) of the object to be processed to be subjected to the aforementioned treatment Step 4A: A step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C, and separating the adhesive layer (X1) from the aforementioned support Step 5A: A step of separating the adhesive layer (X2) from the aforementioned object to be processed. A method for manufacturing a semiconductor device as described in claim 13, wherein the adhesive layer (X2) is hardened by irradiating energy rays to reduce the adhesive force, and the aforementioned step 5A is a step of separating the adhesive layer (X2) from the aforementioned processing object by irradiating the adhesive layer (X2) with energy rays to harden the adhesive layer (X2). A method for manufacturing a semiconductor device comprises the following steps 1B to 4B: step 1B: attaching a processing object to an adhesive layer (X1) of an adhesive sheet manufactured by the method for manufacturing an adhesive sheet as described in claim 6, and attaching a support to an adhesive layer (X2) of the adhesive sheet; step 2B: performing a self-grinding treatment and a One or more processing steps in the singulation process Step 3B: A step of attaching a thermosetting film having thermosetting properties to the surface opposite to the aforementioned adhesive layer (X1) of the processing object to be processed by the aforementioned processing Step 4B: A step of heating the aforementioned adhesive sheet to a temperature above the aforementioned expansion starting temperature (t) and below 120°C, and separating the adhesive layer (X1) from the aforementioned processing object.

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