WO2020196758A1

WO2020196758A1 - Pressure-sensitive adhesive sheet, method for producing pressure-sensitive adhesive sheet, and method for producing semiconductor device

Info

Publication number: WO2020196758A1
Application number: PCT/JP2020/013674
Authority: WO
Inventors: 高志阿久津
Original assignee: リンテック株式会社
Priority date: 2019-03-28
Filing date: 2020-03-26
Publication date: 2020-10-01
Also published as: TW202100687A

Abstract

The present invention pertains to a pressure-sensitive adhesive sheet comprising: a substrate (Y); and a pressure-sensitive adhesive layer (X1) containing a polymer of energy ray-polymerizable components and thermally expandable particles, wherein the polymer is obtained by irradiating, with energy rays, a polymerizable composition which contains, as the energy ray-polymerizable components, a monomer (a1) having an energy ray-polymerizable functional group and a prepolymer (a2) having an energy ray-polymerizable functional group.

Description

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

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

Adhesive sheets are not only used for fixing members semi-permanently, but also for members that are subject to processing and inspection when processing or inspecting building materials, interior materials, electronic components, etc. (hereinafter, "adhesive body"). It may be used as a temporary fixing sheet for temporarily fixing). For example, in the manufacturing process of a semiconductor device, a temporary fixing sheet is used when processing a semiconductor wafer.

In the manufacturing process of a semiconductor device, a semiconductor wafer is processed into a semiconductor chip through a grinding process of reducing the thickness by grinding, an individualizing process of cutting and separating and individualizing. At this time, the semiconductor wafer is subjected to a predetermined process in a state of being temporarily fixed to the temporary fixing sheet. The semiconductor chips obtained by performing the predetermined processing are separated from the temporary fixing sheet, and then, if necessary, an expanding step of widening the distance between the semiconductor chips and a re-arrangement of a plurality of semiconductor chips having the widened distances. After appropriately performing an arranging process, an inverting process of inverting the front and back of the semiconductor chip, etc., the semiconductor chip is mounted on the substrate. Also in each of the above steps, a temporary fixing sheet suitable for each application can be used.

Patent Document 1 discloses a heat-release type pressure-sensitive adhesive sheet for temporary fixing at the time of cutting an electronic component, in which a heat-expandable pressure-sensitive adhesive layer containing heat-expandable microspheres is provided on at least one surface of a base material. .. According to the document, the heat-removable adhesive sheet can secure a contact area of a predetermined size with respect to the adherend when cutting an electronic component, and thus exhibits adhesiveness capable of preventing adhesive defects such as chip skipping. On the other hand, there is a description that if the heat-expandable microspheres are expanded by heating after use, the contact area with the adherend can be reduced and the microspheres can be easily peeled off.

Japanese Patent No. 3594853

By the way, when mounting a semiconductor chip on a substrate, a step of attaching the semiconductor chip to the substrate via a thermosetting film-like adhesive called a die attach film (hereinafter, also referred to as "DAF") is performed. It has been adopted.
The DAF is attached to one surface of the semiconductor wafer or a plurality of fragmented semiconductor chips, and is divided into the same shape as the semiconductor chip at the same time as the semiconductor wafer is fragmented or after being attached to the semiconductor chip. The semiconductor chip with DAF obtained by individualizing is attached (diatached) to the substrate from the DAF side, and then the semiconductor chip and the substrate are fixed by thermosetting the DAF. At this time, the DAF needs to retain the property of adhering by pressure sensitivity or heating until it is attached to the substrate.

The heat-release type pressure-sensitive adhesive sheet disclosed in Patent Document 1 is formed by expanding a heat-expandable microsphere to form irregularities on the pressure-sensitive adhesive surface and peeling off from an adherend. Since the pressure-sensitive adhesive sheet can reduce the contact area between the pressure-sensitive adhesive layer and the semiconductor chip by forming irregularities, the pressure-sensitive adhesive sheet is more than a temporary fixing sheet that cures the pressure-sensitive adhesive layer by irradiation with energy rays to reduce the adhesive strength. It has the advantage that it can be peeled off from the adherend with a small force.
However, when the semiconductor chip with DAF is used as the adherend of the heat-release type adhesive sheet, the DAF is cured before the die attachment due to the heating when the heat-expandable microspheres are expanded, and the DAF on the substrate is cured. Adhesive strength may decrease. It is desirable to suppress the decrease in the adhesive strength of the DAF because it causes a decrease in the bonding reliability between the semiconductor chip and the substrate.
On the other hand, in order to suppress the progress of curing of DAF before die attachment, if a heat-expandable microsphere having a low expansion start temperature is used as a heat-expandable microsphere so that it can be heat-peeled at a low temperature, an adhesive sheet can be manufactured. In the process, problems such as unintentional expansion of thermally expandable microspheres may occur. As a result, the performance as a temporary fixing sheet may be impaired, such as a decrease in adhesive strength and an tendency for air to be squeezed (air enters between the adherend and the adhesive sheet) at the time of sticking. ..

In order to suppress unintended expansion in the pressure-sensitive adhesive sheet manufacturing process, it is effective to omit the heating step in the pressure-sensitive adhesive sheet manufacturing process as much as possible. As one of the methods, a method of forming a coating film using the energy ray-polymerizable component and then irradiating the energy ray to polymerize the energy ray-polymerizable component to form a pressure-sensitive adhesive layer can be considered.
Since the energy ray-polymerizable component before polymerization has a low molecular weight and the viscosity can be easily adjusted, it is not necessary to use a diluent or the like when applying the component, and the heating and drying step when forming the pressure-sensitive adhesive layer can be omitted. it can. However, when an energy ray-polymerizable component is used to form the pressure-sensitive adhesive layer, the composition of the energy ray-polymerizable component simultaneously affects both the formability and the performance of the pressure-sensitive adhesive layer. It was difficult to do.

The present invention has been made in view of the above problems, and even when the pressure-sensitive adhesive layer is formed by an energy ray-polymerizable component, good formability of the pressure-sensitive adhesive layer can be obtained, and sufficient for temporary fixing. It is an object of the present invention to provide an adhesive sheet having excellent adhesive strength and excellent peelability at the time of heat peeling, a method for producing the adhesive sheet, and a method for producing a semiconductor device using the adhesive sheet.

The present inventors have a substrate, a polymer of an energy ray-polymerizable component, and a pressure-sensitive adhesive layer containing heat-expandable particles, and the polymer is a monomer having an energy ray-polymerizable functional group and a monomer. It has been found that the above-mentioned problems can be solved by an adhesive sheet which is a polymer obtained by irradiating an energy ray-polymerizable component containing a prepolymer having an energy ray-polymerizable functional group with energy rays.
That is, the present invention relates to the following [1] to [15].
[1] A pressure-sensitive adhesive sheet comprising a base material (Y) and a pressure-sensitive adhesive layer (X1) containing a polymer of an energy ray-polymerizable component and heat-expandable particles.
An energy ray is added to a polymerizable composition in which the polymer contains a monomer (a1) having an energy ray-polymerizable functional group and a prepolymer (a2) having an energy ray-polymerizable functional group as the energy ray-polymerizable component. An adhesive sheet that is a polymer formed by irradiation.
[2] The pressure-sensitive adhesive sheet according to the above [1], wherein the component (a2) contains a prepolymer having two energy ray-polymerizable functional groups and having the energy ray-polymerizable functional groups at both ends.
[3] The pressure-sensitive adhesive sheet according to the above [1] or [2], wherein the mass average molecular weight (Mw) of the component (a2) is 10,000 to 350,000.
[4] The content ratio [(a2) / (a1)] of the component (a2) and the component (a1) in the polymerizable composition is 10/90 to 70/30 on a mass basis. , The adhesive sheet according to any one of the above [1] to [3].
[5] The pressure-sensitive adhesive sheet according to any one of [1] to [4] above, wherein the polymerizable composition contains a monomer having three or more energy ray-polymerizable functional groups as the component (a1).
[6] The pressure-sensitive adhesive sheet according to any one of [1] to [5] above, wherein the polymerizable composition contains a monomer having an energy ray-polymerizable functional group and a hydroxy group as the component (a1). ..
[7] The above-mentioned [1] to [6], wherein the polymerizable composition contains a monomer having an energy ray-polymerizable functional group and an alicyclic hydrocarbon group as the component (a1). The described adhesive sheet.
[8] The pressure-sensitive adhesive sheet according to any one of the above [1] to [7], wherein the pressure-sensitive adhesive layer (X1) has a thickness of 5 to 150 μm at 23 ° C.
[9] The pressure-sensitive adhesive sheet according to any one of [1] to [8] above, wherein the expansion start temperature (t) of the thermally expandable particles is 50 to 110 ° C.
[10] The base material (Y), the pressure-sensitive adhesive layer (X1) provided on one surface side of the base material (Y), and the pressure-sensitive adhesive layer provided on the other surface side of the base material (Y) ( The adhesive sheet according to any one of the above [1] to [9], which has X2) and.
[11] The method for producing the adhesive sheet according to any one of the above [1] to [10].
The method of forming the pressure-sensitive adhesive layer (X1) is to irradiate 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. A method for producing an adhesive sheet, which comprises a step of
[12] The object to be processed is attached to the adhesive sheet according to any one of [1] to [10] above, and the object to be processed is attached.
The object to be processed is subjected to one or more treatments selected from grinding treatment and individualization treatment.
A method for manufacturing a semiconductor device, which comprises a step of heating the pressure-sensitive adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) to expand the pressure-sensitive adhesive layer (X1) after the treatment.
[13] A method for manufacturing a semiconductor device including the following steps 1A to 5A.
Step 1A: A step of attaching the object to be processed to the adhesive layer (X2) of the adhesive sheet according to the above [10], and attaching a support to the adhesive layer (X1) of the adhesive sheet. Step 2A: The above. Step of applying one or more treatments selected from grinding treatment and individualization treatment to the work object Step 3A: The work object to be processed is on the opposite side of the pressure-sensitive adhesive layer (X2). Step of attaching a thermosetting film having thermosetting property to the surface Step 4A: The adhesive sheet is heated to 120 ° C. or higher at the expansion start temperature (t) or higher, and the adhesive layer (X1) and the support are provided. Step 5A: Step of separating the pressure-sensitive adhesive layer (X2) from the object to be processed [14] The pressure-sensitive adhesive layer (X2) is hardened by irradiating with energy rays to reduce the adhesive strength. Adhesive layer,
The step 5A is a step of curing the pressure-sensitive adhesive layer (X2) by irradiating the pressure-sensitive adhesive layer (X2) with energy rays to separate the pressure-sensitive adhesive layer (X2) from the object to be processed. The method for manufacturing a semiconductor device according to [13].
[15] A method for manufacturing a semiconductor device including the following steps 1B to 4B.
Step 1B: A step of attaching the object to be processed to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet according to the above [10], and attaching a support to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet Step 2B: Step of applying one or more treatments selected from grinding treatment and individualization treatment to the processing target Step 3B: The processing target on the opposite side to the pressure-sensitive adhesive layer (X1) of the processed object. Step of attaching a heat-curable film having heat-curing property to a surface Step 4B: The pressure-sensitive adhesive sheet is heated to 120 ° C. or higher at the expansion start temperature (t) or higher to form an adhesive layer (X1) and the processing target. The process of separating things

According to the present invention, even when the pressure-sensitive adhesive layer is formed by an energy ray-polymerizable component, good bondability of the pressure-sensitive adhesive layer can be obtained, and while having sufficient adhesive strength at the time of temporary fixing, at the time of heat peeling. It is possible to provide a pressure-sensitive adhesive sheet having excellent peelability, a method for manufacturing the pressure-sensitive adhesive sheet, and a method for manufacturing a semiconductor device using the pressure-sensitive adhesive sheet.

It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet of this invention. It is sectional drawing which shows an example of the structure of the pressure-sensitive adhesive sheet of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention. It is sectional drawing explaining an example of the process of the manufacturing method of the semiconductor device of this invention.

In the present specification, the "active ingredient" refers to an ingredient contained in the target composition excluding the diluting solvent.
Further, in the present specification, the mass average molecular weight (Mw) is a value in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method, and is specifically measured based on the method described in Examples. It is the value that was set.

In the present specification, for example, "(meth) acrylic acid" means both "acrylic acid" and "methacrylic acid", and other similar terms are also used.
Further, in the present specification, the lower limit value and the upper limit value described stepwise with respect to a preferable numerical range (for example, a range such as content) can be independently combined. For example, from the description of "preferably 10 to 90, more preferably 30 to 60", the "favorable lower limit value (10)" and the "more preferable upper limit value (60)" are combined to obtain "10 to 60". You can also do it.

In the present specification, the "energy beam" means an electromagnetic wave or a charged particle beam having an energy quantum, and examples thereof include ultraviolet rays, radiation, and electron beams. Ultraviolet rays can be irradiated by using, for example, an electrodeless lamp, a high-pressure mercury lamp, a metal halide lamp, a UV-LED, or the like as an ultraviolet source. The electron beam can be irradiated with an electron beam generated by an electron beam accelerator or the like.
As used herein, the term "energy ray polymerizable" means the property of polymerizing by irradiating with energy rays.

In the present specification, whether the "layer" is a "non-thermally expanding layer" or a "thermally expanding layer" is determined as follows.
When the layer to be judged contains the heat-expandable particles, the layer is heat-treated at the expansion start temperature (t) of the heat-expandable particles for 3 minutes. If the volume change rate calculated from the following formula is less than 5%, the layer is judged to be a "non-thermally expandable layer", and if it is 5% or more, the layer is a "thermally expandable layer". Judge that there is.
Volume change rate (%) = {(volume of the layer after heat treatment-volume of the layer before heat treatment) / volume of the layer before heat treatment} × 100
The layer containing no thermally expandable particles is referred to as a "non-thermally expandable layer".

In the present specification, the "front surface" of the semiconductor wafer and the semiconductor chip refers to the surface on which the circuit is formed (hereinafter, also referred to as the "circuit surface"), and the "back surface" of the semiconductor wafer and the semiconductor chip is the circuit formed. Refers to the surface that is not.

[Adhesive sheet]
The pressure-sensitive adhesive sheet according to one aspect of the present invention is a pressure-sensitive adhesive sheet having a base material (Y) and a pressure-sensitive adhesive layer (X1) containing a polymer of an energy ray-polymerizable component and heat-expandable particles. The coalescence irradiates a polymerizable composition containing a monomer (a1) having an energy ray-polymerizable functional group and a prepolymer (a2) having an energy ray-polymerizable functional group as the energy ray-polymerizable component with energy rays. It is an adhesive sheet, which is a polymer made of steel.

In the pressure-sensitive adhesive sheet of one aspect of the present invention, the heat-expandable particles contained in the pressure-sensitive adhesive layer (X1) are heated to a temperature equal to or higher than the expansion start temperature (t) to expand, thereby expanding the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X1). It is peeled off from the adherend by forming irregularities on the surface. In the pressure-sensitive adhesive sheet of one aspect of the present invention, the contact area between the pressure-sensitive adhesive layer (X1) and the adherend can be reduced by forming the unevenness, so that the adhesion between the pressure-sensitive adhesive sheet and the adherend is remarkably improved. Can be lowered. Thereby, the pressure-sensitive adhesive sheet according to one aspect of the present invention can be peeled off from the adherend by the weight of the pressure-sensitive adhesive sheet or the weight of the adherend without applying a peeling force at the time of heat peeling. Specifically, for example, when the pressure-sensitive adhesive sheet according to one aspect of the present invention is heat-peeled from the adherend, the pressure-sensitive adhesive sheet is peeled off by dropping the pressure-sensitive adhesive sheet from the adherend by gravity with the pressure-sensitive adhesive sheet side facing downward. be able to.
In addition, in this specification, a state in which an adhesive sheet is peeled off from an adherend or peeled off without applying a force for peeling off the adhesive sheet is referred to as "self-peeling". In addition, such a property is referred to as "self-peeling property".
As described above, since the pressure-sensitive adhesive sheet of one aspect of the present invention reduces the contact area between the pressure-sensitive adhesive layer (X1) and the adherend at the time of heat peeling, the pressure-sensitive adhesive layer is cured by energy ray irradiation. It is superior in self-peeling property to the temporary fixing sheet that reduces the adhesive strength.

Further, the polymer of the energy ray-polymerizable component contained in the pressure-sensitive adhesive layer (X1) contained in the pressure-sensitive adhesive sheet of one aspect of the present invention is a monomer (a1) having an energy ray-polymerizable functional group and an energy ray-polymerizable functional group. It is a polymer obtained by irradiating a polymerizable composition containing a prepolymer (a2) having the above with energy rays. Since the energy ray-polymerizable component can be polymerized after the coating film is formed, it is not necessary to use a high molecular weight adhesive resin and a solvent as a diluent thereof when forming the coating film. As a result, when the pressure-sensitive adhesive layer (X1) is formed by using the polymerizable composition, heat-drying for removing the solvent can be omitted, and unintended expansion of the heat-expandable particles during heat-drying can be performed. It can be suppressed.
Further, in the pressure-sensitive adhesive sheet of one aspect of the present invention, at least two kinds of compounds, a monomer (a1) having an energy ray-polymerizable functional group and a prepolymer (a2) having an energy ray-polymerizable functional group, are formed into a pressure-sensitive adhesive layer. When used in, an excellent adhesive layer formability can be obtained, and sufficient adhesive strength and excellent self-peeling property can be obtained. This is because the polymerizable composition having the above composition has a viscosity suitable for forming a coating film, and the polymer formed by energy ray irradiation has an appropriate cohesive force, and has adhesive strength and self-peeling property. It is considered that this is due to the improvement of the balance with.

The structure of the pressure-sensitive adhesive sheet according to one aspect of the present invention may be any one having a base material (Y) and a pressure-sensitive adhesive layer (X1), but depending on the application, the base material (Y) and the pressure-sensitive adhesive layer (X1) ) May be provided.
For example, when the pressure-sensitive adhesive sheet according to one aspect of the present invention is used for processing an adherend, it is applied to one surface side of the base material (Y) and the base material (Y) from the viewpoint of improving the processability of the adherend. It is preferable to have a structure (that is, a structure of a double-sided pressure-sensitive adhesive sheet) having the provided pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) provided on the other surface side of the base material (Y). .. By having this structure, the adherend is attached to one of the adhesive layers (X1) and the adhesive layer (X2), and the support is attached to the other adhesive layer. Can be done. By fixing the adherend to the support via the adhesive sheet, vibration of the adherend, misalignment, damage to fragile objects to be processed, etc. are suppressed when the adherend is processed. However, the processing accuracy and processing speed can be improved.
In the following description, unless otherwise specified, the "double-sided adhesive sheet" refers to the base material (Y), the pressure-sensitive adhesive layer (X1) provided on one surface side of the base material (Y), and the base. It shall mean an adhesive sheet having an adhesive layer (X2) provided on the other surface side of the material (Y).

The pressure-sensitive adhesive sheet according to one aspect of the present invention may have a release material on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X1). Further, when the pressure-sensitive adhesive sheet of one aspect of the present invention has the structure of a double-sided pressure-sensitive adhesive sheet, it has a release material on the pressure-sensitive adhesive surface of at least one of the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2). May be good.

Next, the configuration of the pressure-sensitive adhesive sheet according to one aspect of the present invention will be described more specifically with reference to the drawings.

[Composition of adhesive sheet]
Examples of the pressure-sensitive adhesive sheet according to one aspect of the present invention include a pressure-sensitive adhesive sheet 1a having a pressure-sensitive adhesive layer (X1) on a base material (Y) as shown in FIG. 1 (a).
The pressure-sensitive adhesive sheet according to one aspect of the present invention may have a structure in which the release material 10 is further provided on the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer (X1), as in the pressure-sensitive adhesive sheet 1b shown in FIG. 1 (b).

As another aspect of the pressure-sensitive adhesive sheet of the present invention, those having the structure of the double-sided pressure-sensitive adhesive sheet can be mentioned.
As the pressure-sensitive adhesive sheet having such a structure, for example, as shown in FIG. 2A, both sides have a structure in which the base material (Y) is sandwiched between the pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2). Adhesive sheet 2a can be mentioned.
Further, as in the double-sided adhesive sheet 2b shown in FIG. 2B, the release material 10a is further provided on the adhesive surface of the adhesive layer (X1), and the release material is further provided on the adhesive surface of the adhesive layer (X2). It may be configured to have 10b.

In the double-sided pressure-sensitive adhesive sheet 2b shown in FIG. 2B, the peeling force when the release material 10a is peeled from the pressure-sensitive adhesive layer (X1) and the peeling force when the release material 10b is peeled off from the pressure-sensitive adhesive layer (X2). When both release materials are pulled outward and attempted to be peeled off, a phenomenon may occur in which the pressure-sensitive adhesive layer is divided and peeled off along with the two release materials. From the viewpoint of suppressing such a phenomenon, it is preferable to use two types of release materials designed so that the two

release materials

10a and 10b have different release forces from the pressure-sensitive adhesive layers attached to each other.

As an adhesive sheet of another aspect, in the double-sided adhesive sheet 2a shown in FIG. 2A, one of the adhesive surfaces of the adhesive layer (X1) and the adhesive layer (X2) is peeled off on both sides. A double-sided adhesive sheet having a structure in which the release material is laminated in a roll shape may be used.

The pressure-sensitive adhesive sheet according to one aspect of the present invention may or may not have another layer between the base material (Y) and the pressure-sensitive adhesive layer (X1). Further, when the pressure-sensitive adhesive sheet of one aspect of the present invention is the double-sided pressure-sensitive adhesive sheet, in addition to the above, even if another layer is provided between the base material (Y) and the pressure-sensitive adhesive layer (X2). Well, it does not have to have other layers.
However, it is preferable that a layer capable of suppressing expansion on the adhesive layer (X1) is directly laminated on the surface opposite to the adhesive surface, and the base material (Y) is directly laminated. Is more preferable.

<Base material (Y)>
Examples of the material for forming the base material (Y) include resins, metals, and paper materials, which can be appropriately selected depending on the use of the pressure-sensitive adhesive sheet according to 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; polyethylene terephthalate and poly. Polyimide-based resins such as butylene terephthalate and polyethylene naphthalate; polystyrene; acrylonitrile-butadiene-styrene copolymer; cellulose triacetate; polycarbonate; urethane resins such as polyurethane and acrylic-modified polyurethane; polymethylpentene; polysulfone; polyether ether ketone; Polyether sulfone; polyphenylene sulfide; polyimide resin such as polyetherimide and polyimide; polyamide resin; acrylic resin; fluorine resin and the like can be mentioned.
Examples of the metal include aluminum, tin, chromium, titanium and the like.
Examples of the paper material include thin leaf paper, medium-quality paper, high-quality paper, impregnated paper, coated paper, art paper, parchment paper, and glassin paper.
Among these, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate are preferable.

These forming materials may be composed of one kind, or two or more kinds may be used in combination.
Examples of the base material (Y) in which two or more kinds of forming materials are used in combination include a paper material laminated with a thermoplastic resin such as polyethylene, a resin film containing the resin, or a sheet having a metal layer formed on the surface of the sheet. Can be mentioned.
Examples of the method for forming the metal layer include a method of vapor-depositing a metal by a PVD method such as vacuum deposition, sputtering, and ion plating, a method of attaching a metal foil using a general adhesive, and the like.

From the viewpoint of improving the interlayer adhesion between the base material (Y) and other layers to be laminated, the surface of the base material (Y) is surface-treated by an oxidation method, an unevenness method, etc., easy-adhesion treatment, and primer treatment. Etc. may be applied.
Examples of the oxidation method include corona discharge treatment, plasma discharge treatment, chromic acid treatment (wet), hot air treatment, ozone irradiation treatment, ultraviolet irradiation treatment and the like. In addition, examples of the unevenness method include a sandblasting method and a solvent treatment method.

The base material (Y) contains, for example, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a slip agent, an anti-blocking agent, a colorant, and the like as additives for the base material together with the above resin. You may. These base material additives may be used alone or in combination of two or more.
When the base material (Y) contains the base material additive together with the resin, the content of each base material additive is preferably 0.0001 to 20 parts by mass with respect to 100 parts by mass of the resin. More preferably, it is 0.001 to 10 parts by mass.

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

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

(Storage modulus of substrate (Y) at 23 ° C. E'(23))
The storage elastic modulus E'(23) of the base material (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 ×. It is 10 ⁹ Pa, more preferably 1.0 × 10 ⁹ to 4.0 × 10 ⁹ Pa.
If the substrate (Y) storage modulus E 'of (23) is 5.0 × ¹⁰ 7 Pa or more, can be effectively suppressed swelling of the surface of the substrate (Y) side of the pressure-sensitive adhesive layer (X1) At the same time, the deformation resistance of the adhesive sheet can be improved. On the other hand, the base material (Y) the storage elastic modulus E 'of (23) is equal to or less than 5.0 × ¹⁰ 9 Pa, it is possible to improve the handleability of the adhesive sheet.
In the present specification, the storage elastic modulus E'(23) of the base material (Y) means a value measured by the method described in Examples.

(Storage modulus E'(t) at the expansion start temperature (t) of the base material (Y))
The storage elastic modulus E'(t) of the heat-expandable particles of the base material (Y) at the expansion start temperature (t) is preferably 5.0 × 10 ⁶ to 4.0 × 10 ⁹ Pa, more preferably 2. It is 0 × 10 ⁸ to 3.0 × 10 ⁹ Pa, more preferably 5.0 × 10 ⁸ to 2.5 × 10 ⁹ Pa.
When the storage elastic modulus E'(t) of the base material (Y) is 5.0 × 10 ⁶ Pa or more, the expansion of the surface of the pressure-sensitive adhesive layer (X1) on the base material (Y) side can be efficiently suppressed. At the same time, the deformation resistance of the adhesive sheet can be improved. On the other hand, the base material (Y) the storage elastic modulus E of the '(t) is equal to or smaller than 4.0 × 10 9 ^Pa, it is possible to improve the handleability of the adhesive sheet.
In the present specification, the storage elastic modulus E'(t) of the base material (Y) means a value measured by the method described in Examples.

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

<Adhesive layer (X1)>
The pressure-sensitive adhesive layer (X1) contains a polymer of energy ray-polymerizable components and thermally expandable particles.
The polymer is 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 as the energy ray-polymerizable component. ) (Hereinafter, also referred to as “component (a2)”), which is a polymer obtained by irradiating a polymerizable composition (hereinafter, also referred to as “polymerizable composition (x-1)”) with energy rays.
In addition, in this specification, a prepolymer means a compound formed by polymerizing a monomer, and a compound capable of forming 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 polymerizes by irradiation with energy rays and has an energy ray-polymerizable functional group.
Examples of the energy ray-polymerizable functional group include those having a carbon-carbon double bond such as a (meth) acryloyl group, a vinyl group, and an allyl group. In the present specification, a functional group containing a vinyl group or a substituted vinyl group as a part thereof, such as a (meth) acryloyl group and an allyl group, and a vinyl group or a substituted vinyl group itself are referred to as a "vinyl group-containing group". May be collectively referred to as.
Hereinafter, each component contained in the polymerizable composition (x-1) will be described.

[Monomer having an energy ray-polymerizable functional group (a1)]
The monomer (a1) having an energy ray-polymerizable functional group may be any monomer having an energy ray-polymerizable functional group, and in addition to the energy ray-polymerizable functional group, a hydrocarbon group and an energy ray-polymerizable functional group It may have a functional group other than the above.

Examples of the hydrocarbon group contained in the component (a1) include an aliphatic hydrocarbon group, an aromatic hydrocarbon group, and a group combining these groups.
The aliphatic hydrocarbon group may be a linear or branched aliphatic hydrocarbon group, or may be an alicyclic hydrocarbon group.
Examples of the linear or branched aliphatic hydrocarbon group include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, tert-butyl group, sec-butyl group and n-pentyl. Group, n-hexyl group, 2-ethylhexyl group, n-octyl group, isooctyl group, n-decyl group, n-dodecyl group, n-myristyl group, n-palmityl group, n-stearyl group, etc. There are 20 aliphatic hydrocarbon groups.
Examples of the alicyclic hydrocarbon group include an alicyclic hydrocarbon group having 3 to 20 carbon atoms such as a cyclopentyl group, a cyclohexyl group and an isobornyl group.
Examples of the aromatic hydrocarbon group include a phenyl group.
Examples of the group in which the aliphatic hydrocarbon group and the aromatic hydrocarbon group are combined include a phenoxyethyl group and a benzyl group.
Among these, the component (a1) has an energy ray-polymerizable functional group and a linear or branched aliphatic hydrocarbon group from the viewpoint of further improving the adhesive strength of the pressure-sensitive adhesive layer (X1). Monomer (a1-1) (hereinafter, also referred to as "(a1-1) component"), monomer (a1-2) having an energy ray-polymerizable functional group and an alicyclic hydrocarbon group (hereinafter, "(a1-a1-)" 2) It is preferable to contain "components") and the like.

When the component (a1) contains the component (a1-1), the content thereof is preferably 20 to 80% by mass, more preferably 40 to 40% by mass, based on the total amount (100% by mass) of the components (a1). It is 70% by mass, more preferably 50 to 60% by mass.
When the component (a1) contains the component (a1-2), the content thereof is preferably 5 to 60% by mass, more preferably 10 to 10 to the total amount (100% by mass) of the components (a1). It is 40% by mass, more preferably 20 to 30% by mass.

The monomer having an energy ray-polymerizable functional group and a functional group other than the energy ray-polymerizable functional group includes, for example, a hydroxy group, a carboxy group, a thiol group, 1 or a functional group other than the energy ray-polymerizable functional group. Examples thereof include a monomer having a secondary amino group and the like. Among these, the component (a1) is a monomer (a1-3) having an energy ray-polymerizable functional group and a hydroxy group from the viewpoint of further improving the formability of the pressure-sensitive adhesive layer (X1) (hereinafter, "(a1)". -3) It is preferable to contain (also referred to as "component").
When the component (a1) contains the component (a1-3), the content thereof is preferably 1 to 60% by mass, more preferably 5 to 5 to the total amount (100% by mass) of the components (a1). It is 30% by mass, more preferably 10 to 20% by mass.

The number of energy ray-polymerizable functional groups contained in the component (a1) may be one or two or more. Further, from the viewpoint of further improving the self-peeling property of the pressure-sensitive adhesive layer (X1), the component (a1) is a monomer (a1-4) having three or more energy ray-polymerizable functional groups (hereinafter, "(a1-4)". ) Ingredients ”) are preferably contained.
When the component (a1) contains the component (a1-4), the content thereof is preferably 1 to 20% by mass, more preferably 2 to 2 to the total amount (100% by mass) of the components (a1). It is 15% by mass, more preferably 3 to 10% by mass.

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

<< Polymerizable vinyl monomer >>
The polymerizable vinyl monomer is not particularly limited as long as it has a vinyl group-containing group, and conventionally known ones can be appropriately used.
As the polymerizable vinyl monomer, one type may be used alone, or two or more types may be used in combination.

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

The polymerizable vinyl monomer may further have a functional group other than the vinyl group-containing group in the molecule. Examples of the functional group include a hydroxy group, a carboxy group, a thiol group, a primary or secondary amino group and the like. Among these, a polymerizable vinyl monomer having a hydroxy group corresponding to the above component (a1-3) is preferable.
Examples of the polymerizable vinyl monomer having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3 Hydroxyalkyl (meth) acrylates such as -hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; and hydroxy group-containing acrylamides such as N-methylol acrylamide and N-methylol methacrylate can be mentioned. Examples of the polymerizable vinyl monomer having a carboxy group include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. Among these, 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate are preferable.

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 and α. -Sterite-based monomers such as methylstyrene; diene-based monomers such as butadiene, isoprene, and chloroprene; nitrile-based monomers such as acrylonitrile and methacrylonitrile; acrylamide, methacrylicamide, N-methylacrylamide, and N-methyl. Amide-based monomers such as methacrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N-vinylpyrrolidone; N, N-diethylaminoethyl (meth) acrylate, N-( Meta) Examples thereof include tertiary amino group-containing monomers such as acrylamide and the like.

<< Polyfunctional (meth) acrylate monomer >>
The polyfunctional (meth) acrylate monomer is not particularly limited as long as it is a monomer having two or more (meth) acryloyl groups in one molecule, and conventionally known ones can be appropriately used.
One type of polyfunctional (meth) acrylate monomer may be used alone, or two or more types may be used in combination.

Examples of the polyfunctional (meth) acrylate monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol di (meth) acrylate. ) Acrylate, neopentyl glycol adipate di (meth) acrylate, neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone-modified dicyclopentenyl di (meth) acrylate, ethylene oxide-modified phosphoric acid Bifunctional (meth) acrylate monomers such as di (meth) acrylate, di (acryloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, isocyanurate ethylene oxide-modified diacrylate; trimethyl propantri (meth) acrylate, Dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide-modified trimethylolpropantri (meth) acrylate, tris (acryloxyethyl) isocyanurate, Bis (acryloxyethyl) hydroxyethyl isocyanurate, isocyanuric acid ethylene oxide-modified triacrylate, ε-caprolactone-modified tris (acryroxyethyl) isocyanurate, diglycerin tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, propionic acid Polyfunctional (meth) acrylate monomers corresponding to the above (a1-4) components such as modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and caprolactone modified dipentaerythritol hexa (meth) acrylate Can be mentioned.

<< Content of component (a1) >>
The total content of the polymerizable vinyl monomer in the polymerizable composition (x-1) is preferably 10 to 80 with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1). It is by mass, more preferably 30 to 75% by mass, and even more preferably 50 to 70% by mass.
The total content of the polyfunctional (meth) acrylate monomer in the polymerizable composition (x-1) is preferably 0 with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1). .5 to 15% by mass, more preferably 1 to 10% by mass, still more preferably 2 to 5% by mass.
The total content of the component (a1) in the polymerizable composition (x-1) is preferably 15 to 90% by mass with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1). %, More preferably 35 to 80% by mass, still more preferably 55 to 75% by mass.

[Prepolymer having an energy ray-polymerizable functional group (a2)]
Examples of the prepolymer (a2) having an energy ray-polymerizable functional group include a prepolymer having one energy ray-polymerizable functional group, a prepolymer having two or more energy ray-polymerizable functional groups, and the like. Among these, the component (a2) contains a prepolymer having two or more energy ray-polymerizable functional groups from the viewpoint of forming a pressure-sensitive adhesive layer having excellent self-peeling properties and less contamination of the adherend after peeling. It is preferable to contain a prepolymer having two energy ray-polymerizable functional groups, and a prepolymer having two energy ray-polymerizable functional groups and having the energy ray-polymerizable functional groups at both ends. Is more preferable to contain.

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

《Multifunctional (meth) acrylate prepolymer》
The polyfunctional (meth) acrylate prepolymer is not particularly limited as long as it is a prepolymer having two or more (meth) acryloyl groups in one molecule, and conventionally known prepolymers can be appropriately used.
One type of polyfunctional (meth) acrylate prepolymer may be used alone, or two or more types may be used in combination.

Examples of the polyfunctional (meth) acrylate prepolymer include urethane acrylate-based prepolymers, polyester acrylate-based prepolymers, epoxy acrylate-based prepolymers, polyether acrylate-based prepolymers, polybutadiene acrylate-based prepolymers, and silicone acrylate-based prepolymers. Examples thereof include polyacrylic acrylate-based prepolymers.

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

Examples of the polyalkylene polyol used for producing the urethane acrylate-based prepolymer include polypropylene glycol, polyethylene glycol, polybutylene glycol, polyhexylene glycol and the like, and among these, polypropylene glycol is preferable. When the number of functional groups of the obtained urethane acrylate-based prepolymer is 3 or more, for example, glycerin, trimethylolpropane, triethanolamine, pentaerythritol, ethylenediamine, diethylenetriamine, sorbitol, sucrose and the like may be appropriately combined.

Examples of the polyisocyanate used for producing the urethane acrylate-based prepolymer include aliphatic diisocyanates such as hexamethylene diisocyanate and trimethylene diisocyanate; aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate and diphenyl diisocyanate; dicyclohexylmethane diisocyanate. , Alicyclic diisocyanate such as isophorone diisocyanate, etc. Among these, aliphatic diisocyanate is preferable, and hexamethylene diisocyanate is more preferable. The polyisocyanate is not limited to bifunctional ones, and trifunctional or higher functional ones can also be used.

Examples of the (meth) acrylic acid derivative used in the production of urethane acrylate-based prepolymers include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl acrylate and 4-hydroxybutyl acrylate; 2-isocyanate ethyl acrylate, 2-. Examples thereof include isocyanate ethyl methacrylate and 1,1-bis (acryloxymethyl) ethyl isocyanate, and among these, 2-isocyanate ethyl acrylate is preferable.

As another method for producing a urethane acrylate-based prepolymer, a hydroxy group contained in a compound such as a polyalkylene polyol, a polyether polyol, a polyester polyol, a hydrogenated isoprene having a hydroxy group terminal, and a hydrogenated butadiene having a hydroxy group terminal, and an isocyanate. Examples thereof include a method of reacting with the −N = C = O moiety of the 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 (acryloxymethyl) ethyl isocyanate and the like can be used.

The polyester acrylate-based prepolymer can be obtained, for example, by esterifying the hydroxy groups of a polyester prepolymer having hydroxy groups at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid. Can be done. It can also be obtained by esterifying the hydroxy group at the end of the prepolymer obtained by adding an alkylene oxide to a polyvalent carboxylic acid with (meth) acrylic acid.

The epoxy acrylate-based prepolymer can be obtained, for example, by reacting an oxylan ring of a relatively low molecular weight bisphenol type epoxy resin, novolak type epoxy resin, or the like with (meth) acrylic acid to esterify it. It is also possible to use a carboxy-modified epoxy acrylate-based prepolymer in which the epoxy acrylate-based prepolymer is partially modified with a dibasic carboxylic acid anhydride.

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

The polyacrylic acrylate-based prepolymer may have an acryloyl group in the side chain, or may have an acryloyl group at both ends or one end. A polyacrylic acrylate-based prepolymer having an acryloyl group in the side chain can be obtained, for example, by adding glycidyl methacrylate to the carboxy group of polyacrylic acid. Further, in the polyacrylic acrylate-based prepolymer having acryloyl groups at both ends, for example, an acryloyl group is introduced at both ends by utilizing the polymerization growth terminal structure of the polyacrylate prepolymer synthesized by the ATRP (Atom Transfer Radical Polymerization) method. Can be obtained by doing.

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 polyfunctional (meth) acrylate prepolymer in the polymerizable composition (x-1) is preferably based on the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1). It is 10 to 60% by mass, more preferably 15 to 55% by mass, and even more preferably 20 to 30% by mass.
The total content of the component (a2) in the polymerizable composition (x-1) is preferably 10 to 60% by mass with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1). %, More preferably 15 to 55% by mass, still more preferably 20 to 30% by mass.

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

Among the above energy ray-polymerizable components, the polymerizable composition (x-1) preferably contains a polymerizable vinyl monomer, a polyfunctional (meth) acrylate monomer, and a polyfunctional (meth) acrylate prepolymer.
The total content of the polymerizable vinyl monomer, the polyfunctional (meth) acrylate monomer and the polyfunctional (meth) acrylate prepolymer in the energy ray-polymerizable component contained in the polymerizable composition (x-1) is the energy ray polymerization. With respect to the total amount (100% by mass) of the sex component, it is preferably 80% by mass or more, more preferably 90% by mass or more, further preferably 95% by mass or more, still more preferably 99% by mass or more, and 100% by mass. It may be.

The total content of the energy ray-polymerizable component in the polymerizable composition (x-1) is preferably 70 to 98 with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1). It is by mass, more preferably 75 to 97% by mass, still more preferably 80 to 96% by mass, and even more preferably 82 to 95% by mass.

The polymerizable composition (x-1) of one aspect of the present invention preferably contains thermally expandable particles in addition to the energy ray-polymerizable component. That is, the pressure-sensitive adhesive layer (X1) forms a polymer of the energy ray-polymerizable component by irradiating the polymerizable composition (x-1) containing the energy ray-polymerizable component and the heat-expandable particles with energy rays. It is preferably formed by a method including the steps of

[Thermal expandable particles]
The thermally expandable particles may be particles that expand by heating.
The expansion start temperature (t) of the heat-expandable particles may be appropriately adjusted within the above range according to the use of the pressure-sensitive adhesive sheet. For example, the thermal expandability due to a temperature rise when grinding an adherend is performed. From the viewpoint of suppressing the expansion of the particles, the temperature is preferably 50 ° C. or higher, more preferably 55 ° C. or higher, still more preferably 60 ° C. or higher, still more preferably 70 ° C. or higher, and the heat of the adherend at the time of heat peeling. From the viewpoint of suppressing the change, it is preferably 110 ° C. or lower, more preferably 105 ° C. or lower, still more preferably 100 ° C. or lower, still more preferably 95 ° C. or lower.
In addition, in this specification, the expansion start temperature (t) of a heat-expandable particle means a value measured based on the following method.
[Measurement method of expansion start temperature (t) of thermally expandable particles]
To an aluminum cup with a diameter of 6.0 mm (inner diameter 5.65 mm) and a depth of 4.8 mm, 0.5 mg of the heat-expandable particles to be measured were added, and an aluminum lid (diameter 5.6 mm, thickness 0. A sample on which 1 mm) is placed is prepared.
Using a dynamic viscoelasticity measuring device, the height of the sample is measured with a force of 0.01 N applied by a pressurizer from the upper part of the aluminum lid to the sample. Then, with a force of 0.01 N applied by the pressurizer, it is heated from 20 ° C. to 300 ° C. at a heating rate of 10 ° C./min, the amount of displacement of the pressurizer in the vertical direction is measured, and the displacement in the positive direction is measured. Let the displacement start temperature be the expansion start temperature (t).

The heat-expandable particles are microencapsulated foaming agents composed of an outer shell made of a thermoplastic resin and an inner shell contained in the outer shell and vaporized when heated to a predetermined temperature. It is preferable to have.
The thermoplastic resin constituting the outer shell of the microencapsulating foaming agent is not particularly limited, and a material and composition capable of causing a state change such as melting, dissolution, and rupture at the expansion start temperature (t) of the thermally expandable particles are appropriately used. You can select it.
Examples of the thermoplastic resin include vinylidene chloride-acrylonitrile copolymer, polyvinyl alcohol, polyvinyl butyral, polymethylmethacrylate, polyacrylonitrile, polyvinylidene chloride, polysulfone and the like. One type of these thermoplastic resins may be used alone, or two or more types may be used in combination.

The contained component, which is a component contained in the outer shell of the microencapsulating foaming agent, may be any one that expands at the expansion start temperature (t) of the heat-expandable particles, for example, propane, propylene, butene, n-. Examples thereof include low boiling point liquids such as butane, isobutane, isopentane, neopentane, n-pentane, n-hexane, isohexane, n-heptane, n-octane, cyclopropane, cyclobutane, and petroleum ether.
One of these inclusion components may be used alone, or two or more thereof may be used in combination.
The expansion start temperature (t) of the thermally expandable particles can be adjusted by appropriately selecting the type of the inclusion component.

The average particle size of the heat-expandable particles at 23 ° C. before thermal expansion is preferably 1 to 30 μm, more preferably 4 to 25 μm, still more preferably 6 to 20 μm, still more preferably 10 to 15 μm.
The average particle size (D ₅₀ ) of the heat-expandable particles is a volume medium particle size (D ₅₀ ), and is a laser diffraction type particle size distribution measuring device (for example, manufactured by Malvern, product name “Mastersizer 3000”. ), The cumulative volume frequency calculated from the smaller particle size in the particle distribution of the thermally expandable particles before expansion means the particle size corresponding to 50%.

The 90% particle diameter (D ₉₀ ) of the thermally expandable particles at 23 ° C. before thermal expansion is preferably 2 to 60 μm, more preferably 8 to 50 μm, still more preferably 12 to 40 μm, still more preferably 20 to 30 μm. is there.
The 90% particle size (D ₉₀ ) of the heat-expandable particles is calculated from the smaller particle size in the particle distribution of the heat-expandable particles before expansion measured by using the laser diffraction type particle size distribution measuring device. It means the particle size in which the cumulative volume frequency corresponds to 90%.

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

The content of the heat-expandable particles is preferably 1 with respect to the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1) or the total mass (100% by mass) of the pressure-sensitive adhesive layer (X1). It is ~ 30% by mass, more preferably 2 to 25% by mass, still more preferably 3 to 20% by mass.
When the content of the heat-expandable particles is 1% by mass or more, the peelability at the time of heat peeling tends to be improved. Further, when the content of the heat-expandable particles is 30% by mass or less, the adhesive strength of the pressure-sensitive adhesive layer (X1) is improved, and curling of the pressure-sensitive adhesive sheet is suppressed during heat peeling to improve handleability. There is a tendency to be able to do it.

[Other ingredients]
The polymerizable composition (x-1) may contain other components other than the energy ray-polymerizable component and the heat-expandable particles.
Examples of the other components include a photopolymerization initiator, a tackifier, and an additive for a pressure-sensitive adhesive used in a general pressure-sensitive adhesive other than the above-mentioned components. Among these, the polymerizable composition (x-1) preferably contains a photopolymerization initiator.

《Photopolymerization initiator》
When the polymerizable composition (x-1) contains a photopolymerization initiator, the polymerization of the energy ray-polymerizable component can proceed 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, and the like. 2,2-Diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1- [4- (methylthio) phenyl]- 2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl-2- (hydroxy-2-propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4'-diethylaminobenzophenone, dichlorobenzophenone, 2 -Methylanthraquinone, 2-ethylanthraquinone, 2-tershary-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, Benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2,4,6-trimethylbenzoyl- Examples thereof include diphenyl-phosphine oxide. As the photopolymerization initiator, one type may be used alone, or two or more types may be used in combination.

When the polymerizable composition (x-1) contains a photopolymerization initiator, the content thereof is preferably 0.1 to 10 parts by mass, more preferably 0, with respect to 100 parts by mass of the energy ray-polymerizable component. .2 to 5 parts by mass, more preferably 0.3 to 1 part by mass.
When the content of the photopolymerization initiator is 0.1 parts by mass or more, the polymerization of the energy ray-polymerizable component can proceed more efficiently. On the other hand, when the content is 10 parts by mass or less, it is possible to eliminate or reduce the photopolymerization initiator remaining unreacted, and it is easy to adjust the obtained pressure-sensitive adhesive layer (X1) to desired physical properties. Become.

<< Adhesive agent >>
The tackifier is a component used as needed for the purpose of further improving the adhesive strength.
In the present specification, the “tacking agent” refers to a resin having a mass average molecular weight (Mw) of less than 10,000, and is distinguished from the adhesive resin described later.
The mass average molecular weight (Mw) of the tackifier is less than 10,000, preferably 400 to 9,000, more preferably 500 to 8,000, still more preferably 800 to 5,000.

As the tackifier, for example, it is obtained by copolymerizing a C5 distillate such as rosin resin, terpene resin, styrene resin, penten, isoprene, piperin, 1,3-pentadiene produced by thermal decomposition of petroleum naphtha. Examples thereof include C5-based petroleum resins, C9-based petroleum resins obtained by copolymerizing C9 fractions such as inden and vinyl toluene produced by thermal decomposition of petroleum naphtha, and hydrides obtained by hydrogenating these.

The softening point of the tackifier is preferably 60 to 170 ° C, more preferably 65 to 160 ° C, and even more preferably 70 to 150 ° C.
In the present specification, the "softening point" of the tackifier means a value measured in accordance with JIS K 2531.
As the tackifier, one type may be used alone, or two or more types having different softening points, structures, etc. may be used in combination. When two or more kinds of tackifiers are used, it is preferable that the weighted average of the softening points of the plurality of tackifiers belongs to the above range.

When the polymerizable composition (x-1) contains a tackifier, the content thereof is preferably 0, based on the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1). It is 01 to 65% by mass, more preferably 0.1 to 50% by mass, still more preferably 1 to 40% by mass, and even more preferably 2 to 30% by mass.

<< Additives for adhesives >>
Examples of additives for adhesives include silane coupling agents, antioxidants, softeners (plasticizers), rust inhibitors, pigments, dyes, retarders, reaction accelerators (catalysts), ultraviolet absorbers and the like. Be done. These adhesive additives may be used alone or in combination of two or more.

When the polymerizable composition (x-1) contains an additive for a pressure-sensitive adhesive, the content of each additive for the pressure-sensitive adhesive is preferably 0.0001 to 0.0001 with respect to 100 parts by mass of the energy ray-polymerizable component. It is 20 parts by mass, more preferably 0.001 to 10 parts by mass.

The polymerizable composition (x-1) may contain a solvent such as a diluent within a range not contrary to the object of the present invention, but preferably does not contain a 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, it is possible to omit heating and drying the solvent when forming the pressure-sensitive adhesive layer (X1). The expansion of the heat-expandable particles can be suppressed. In addition, when a solvent is used, the heat-expandable particles may be unevenly distributed on one surface side as the volume decreases during drying, and the adhesion to the base material (Y) or the adhesive strength of the adhesive surface may decrease. It was. On the other hand, in the solvent-free polymerizable composition, the polymerization proceeds in a state where the heat-expandable particles are uniformly dispersed in the energy ray-polymerizable component, and the pressure-sensitive adhesive layer (X1) is formed. Problems are unlikely to occur.
When the polymerizable composition (x-1) contains a solvent, the smaller the content is, the more preferable it is, and preferably 10 based on the total amount (100% by mass) of the active ingredient of the polymerizable composition (x-1). It is mass% or less, more preferably 1% by mass or less, still more preferably 0.1% by mass or less, still more preferably 0.01% by mass or less.

The polymerizable composition (x-1) can be produced by mixing an energy ray-polymerizable component, thermally expandable particles, and other components contained as necessary. Since the obtained polymerizable composition (x-1) has a high molecular weight by subsequent energy ray polymerization, the viscosity is adjusted to an appropriate level by a low molecular weight energy ray polymerizable component when forming a layer. It is possible. Therefore, the polymerizable composition can be used as it is as a coating solution for forming the pressure-sensitive adhesive layer (X1) without adding a solvent such as a diluent.
The pressure-sensitive adhesive layer (X1) formed by irradiating the polymerizable composition (x-1) with energy rays contains a wide variety of polymers obtained by polymerizing energy ray-polymerizable components, and the polymers. Although there are thermally expandable particles dispersed therein, there are circumstances in which it is impossible or approximately impractical to directly identify them by structure and physical properties.

(Adhesive strength of the adhesive layer (X1) at 23 ° C. before thermal expansion)
The adhesive strength of the pressure-sensitive adhesive layer (X1) at 23 ° C. before thermal expansion is preferably 0.1 to 12.0 N / 25 mm, more preferably 0.5 to 9.0 N / 25 mm, and further preferably 1.0 to 1.0. It is 8.0 N / 25 mm, more preferably 1.2 to 7.5 N / 25 mm.
If the adhesive force of the pressure-sensitive adhesive layer (X1) at 23 ° C. before thermal expansion is 0.1 N / 25 mm or more, unintentional peeling from the adherend during temporary fixing, misalignment of the adherend, etc. are more effective. Can be suppressed. On the other hand, when the adhesive strength is 12.0 N / 25 mm or less, the peelability at the time of heat peeling can be further improved.
In the present specification, the adhesive force of the pressure-sensitive adhesive layer means the adhesive force of the silicon mirror wafer with respect to the mirror surface.
Further, in the present specification, the adhesive force of the pressure-sensitive adhesive layer (X1) at 23 ° C. before thermal expansion specifically means a value measured by the method described in Examples.

(Adhesive strength at 23 ° C. after thermal expansion of the adhesive layer (X1))
The adhesive strength of the pressure-sensitive adhesive layer (X1) at 23 ° C. after thermal expansion is preferably 1.5 N / 25 mm or less, more preferably 0.05 N / 25 mm or less, still more preferably 0.01 N / 25 mm or less, still more preferably. Is 0N / 25mm. The adhesive strength of 0 N / 25 mm means the adhesive strength below the measurement limit in the method for measuring the adhesive strength at 23 ° C. after thermal expansion, which will be described later, when the adhesive sheet is fixed for measurement. It also includes cases where the adhesive strength is too small to unintentionally peel off.
In the present specification, the adhesive force of the pressure-sensitive adhesive layer (X1) at 23 ° C. after thermal expansion specifically means a value measured by the method described in Examples.

(Shear storage elastic modulus G'(23) of the pressure-sensitive adhesive layer (X1) at 23 ° C.)
The shear storage elastic modulus G'(23) of the pressure-sensitive 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. It is 0 × 10 ⁷ Pa, more preferably 1.0 × 10 ⁵ to 5.0 × 10 ⁶ Pa.
If the shear storage elastic modulus G'(23) of the pressure-sensitive adhesive layer (X1) is 1.0 × 10 ⁴ Pa or more, the position of the adherend at the time of temporary fixing is displaced, and the pressure-sensitive adhesive layer (X1) of the adherend is Excessive subduction to the water 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, easily irregularities are formed on the surface of the pressure-sensitive adhesive layer (X1), the heating The peelability at the time of peeling tends to be improved.
In the present specification, the shear storage elastic modulus G'(23) of the pressure-sensitive adhesive layer (X1) at 23 ° C. means a value measured by the method described in Examples.

The pressure-sensitive adhesive layer (X1) is a layer containing heat-expandable particles, and the shear storage elastic modulus G'of the pressure-sensitive adhesive layer (X1) can be affected by the heat-expandable particles. From the viewpoint of measuring the shear storage elastic modulus G'excluding the influence of the heat-expandable particles, the pressure-sensitive adhesive layer having the same structure as the pressure-sensitive adhesive layer (X1) except that it does not contain the heat-expandable particles (hereinafter, A "non-expandable pressure-sensitive adhesive layer (X1')") may be prepared, and the shear storage elastic modulus G'of the pressure-sensitive adhesive layer may be measured.

(Shear storage elastic modulus G'(23) of non-expandable pressure-sensitive adhesive layer (X1') at 23 ° C.)
The shear storage elastic modulus G'(23) of the non-expandable pressure-sensitive adhesive layer (X1') at 23 ° C. is preferably 1.0 × 10 ⁴ to 5.0 × 10 ⁷ Pa, more preferably 5.0 × 10. ^{It is 4} to 1.0 × 10 ⁷ Pa, more preferably 1.0 × 10 ⁵ to 5.0 × 10 ⁶ Pa.
If the shear storage elastic modulus G'(23) of the non-expandable pressure-sensitive adhesive layer (X1') is 1.0 × 10 ⁴ Pa or more, the position of the adherend at the time of temporary fixing is displaced, and the adhesive of the adherend. Excessive subduction into the layer (X1) can be suppressed. On the other hand, if the shear storage modulus G '(23) is 5.0 × 10 7 ^Pa or less, the expansion of the thermally expandable particles, easily irregularities are formed on the surface of the pressure-sensitive adhesive layer (X1), the heating The peelability at the time of peeling tends to be improved.

(Shear storage elastic modulus G'(t) at the expansion start temperature (t) of the non-expandable pressure-sensitive adhesive layer (X1'))
The shear storage elastic modulus G'(t) of the non-expandable pressure-sensitive adhesive layer (X1') at the expansion start temperature (t) of the heat-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, still more preferably 5.0 × 10 ⁴ to 1.0 × 10 ⁶ Pa.
If the shear storage elastic modulus G'(t) of the non-expandable pressure-sensitive adhesive layer (X1') is 5.0 × 10 ³ Pa or more, the position of the adherend at the time of temporary fixing is displaced, and the adhesive on the adherend. Excessive subduction into the layer (X1) can be suppressed, curling of the adhesive sheet during heat peeling can be suppressed, and handleability tends to be improved. 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, easily irregularities are formed on the surface of the pressure-sensitive adhesive layer (X1), the heating The peelability at the time of peeling tends to be improved.
In the present specification, the shear storage elastic modulus G'of the non-expandable pressure-sensitive adhesive layer (X1') at a predetermined temperature means a value measured by the method described in Examples.

(Thickness of the adhesive layer (X1) at 23 ° C.)
The thickness of the pressure-sensitive 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 pressure-sensitive adhesive layer (X1) at 23 ° C. is 5 μm or more, sufficient adhesive strength can be easily obtained, and unintentional peeling from the adherend during temporary fixing, misalignment of the adherend, etc. It tends to be suppressed. On the other hand, when the thickness of the pressure-sensitive adhesive layer (X1) at 23 ° C. is 150 μm or less, the peelability at the time of heat peeling can be improved, the curl of the pressure-sensitive adhesive sheet at the time of heat peeling can be suppressed, and the handleability can be improved. There is a tendency.
In addition, in this specification, the thickness of the pressure-sensitive adhesive layer means the value measured by the method described in Example. The thickness of the pressure-sensitive adhesive layer (X1) is a value before expansion of the heat-expandable particles.

<Adhesive layer (X2)>
The pressure-sensitive adhesive layer (X2) is a layer arbitrarily provided on the other surface side of the base material (Y).
The pressure-sensitive adhesive layer (X2) may be a heat-expandable layer or a non-heat-expandable layer, but is preferably a non-heat-expandable layer. The pressure-sensitive adhesive layer (X1) and the pressure-sensitive adhesive layer (X2) have different action mechanisms for reducing the adhesive strength of the pressure-sensitive adhesive layer, thereby reducing the adhesive strength of one of the pressure-sensitive adhesive layers. When doing so, it is possible to prevent the adhesive strength of the other adhesive layer from being unintentionally reduced.

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

The pressure-sensitive adhesive layer (X2) is preferably formed from the pressure-sensitive adhesive composition (x-2) containing a pressure-sensitive adhesive resin. Hereinafter, each component contained in the pressure-sensitive adhesive composition (x-2) will be described.

(Adhesive composition (x-2))
The pressure-sensitive adhesive composition (x-2) contains a pressure-sensitive resin, and if necessary, a cross-linking agent, a pressure-sensitive adhesive, a polymerizable compound, a polymerization initiator, and general pressure-sensitive adhesive other than the above-mentioned components. It may contain an additive for a pressure-sensitive adhesive used in the agent.

[Adhesive resin]
The adhesive resin may be a polymer having adhesiveness by itself and having a mass average molecular weight (Mw) of 10,000 or more.
The mass average molecular weight (Mw) of the adhesive resin is preferably 10,000 to 2 million, more preferably 20,000 to 1.5 million, and further preferably 30,000 from the viewpoint of further improving the adhesive strength of the pressure-sensitive adhesive layer (X2). ~ 1 million.

Examples of the adhesive resin include rubber-based resins such as acrylic resins, urethane-based resins, and polyisobutylene-based resins, polyester-based resins, olefin-based resins, silicone-based resins, and polyvinyl ether-based resins.
One type of these adhesive resins may be used alone, or two or more types may be used in combination.
When these adhesive resins are copolymers having two or more kinds of structural units, the form of the copolymer may be any of a block copolymer, a random copolymer, and a graft copolymer. There may be.

The pressure-sensitive adhesive composition (x-2) containing a pressure-sensitive adhesive resin is a pressure-sensitive adhesive composition that is cured by irradiation with energy rays from the viewpoint of differentiating the action mechanism of reducing the adhesive strength with the pressure-sensitive adhesive layer (X1). It is preferable, and the adhesive resin is more preferably a resin having an energy ray-polymerizable functional group in the side chain of the adhesive resin. By forming from the pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer (X2) can be made into a pressure-sensitive adhesive layer that is cured by energy ray irradiation and whose adhesive strength is reduced.
Examples of the energy ray-polymerizable functional group include those having a carbon-carbon double bond such as a (meth) acryloyl group, a vinyl group, and an allyl group.
Among the above-mentioned energy rays, ultraviolet rays, which are easy to handle, are preferable.
Further, the pressure-sensitive adhesive composition (x-2) has an energy ray-polymerizable functional group together with a pressure-sensitive resin having an energy ray-polymerizable functional group or instead of a pressure-sensitive resin having an energy ray-polymerizable functional group. It may contain a monomer or a prepolymer.
Examples of the monomer or prepolymer having an energy ray-polymerizable functional group include the same energy ray-polymerizable components contained in the above-mentioned polymerizable composition (x-1).

When the pressure-sensitive adhesive composition (x-2) is a pressure-sensitive adhesive composition that is cured by irradiation with energy rays, the pressure-sensitive adhesive composition preferably further contains a photopolymerization initiator.
By containing the photopolymerization initiator, the polymerization of the energy ray-polymerizable component can proceed more efficiently.
Examples of the photopolymerization initiator include the same photopolymerization initiators that may be contained in the polymerizable composition (x-1).
The content of the photopolymerization initiator is preferably 0.01 to 10 parts by mass, more preferably 0.03 with respect to 100 parts by mass of the total amount of the adhesive resin, the monomer and the prepolymer having an energy ray-polymerizable functional group. It is up to 5 parts by mass, more preferably 0.05 to 2 parts by mass.

The adhesive resin preferably contains an acrylic resin from the viewpoint of exhibiting excellent adhesive strength.
The content of the acrylic resin in the pressure-sensitive adhesive composition (x-2) is preferably 30 to 30% with respect to the total amount (100% by mass) of the pressure-sensitive resin contained in the pressure-sensitive adhesive composition (x-2). It is 100% by mass, more preferably 50 to 100% by mass, still more preferably 70 to 100% by mass, and even more preferably 85 to 100% by mass.

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

[Crosslinking agent]
In one aspect of the present invention, when the pressure-sensitive adhesive composition (x-2) contains a pressure-sensitive adhesive resin having a functional group, the pressure-sensitive adhesive composition (x-2) preferably further contains a cross-linking agent.
The cross-linking agent reacts with a tacky resin having a functional group to cross-link the tacky resins with the functional group as a cross-linking starting point.

Examples of the cross-linking agent include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and metal chelate-based cross-linking agents.
As the cross-linking agent, one type may be used alone, or two or more types may be used in combination.
Among these cross-linking agents, isocyanate-based cross-linking agents are preferable from the viewpoint of increasing the cohesive force to improve the adhesive force and the availability.

The content of the cross-linking agent is appropriately adjusted according to the number of functional groups of the adhesive resin, and is preferably 0.01 to 10 parts by mass with respect to 100 parts by mass of the adhesive resin having functional groups. It is more preferably 0.03 to 7 parts by mass, and further preferably 0.05 to 5 parts by mass.

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

[Additives for adhesives]
Examples of the pressure-sensitive adhesive additive include the same pressure-sensitive adhesive additives that the polymerizable composition (x-1) may contain.
When the pressure-sensitive adhesive composition (x-2) does not contain the heat-expandable particles, it is not necessary to avoid heating and drying the heat-expandable particles above the expansion start temperature (t), so that the pressure-sensitive adhesive composition (x) -2) may contain a solvent if necessary.

The pressure-sensitive adhesive composition (x-2) can be produced by mixing a pressure-sensitive resin, a cross-linking agent used as necessary, a pressure-sensitive adhesive, an additive for pressure-sensitive adhesive, and the like.

[Adhesive strength of adhesive layer (X2)]
The adhesive strength of the pressure-sensitive adhesive layer (X2) on the adhesive surface is preferably 0.1 to 10.0 N / 25 mm, more preferably 0.2 to 8.0 N / 25 mm, and further preferably 0.4 to 6.0 N /. It is 25 mm, more preferably 0.5 to 4.0 N / 25 mm.
When the adhesive force on the adhesive surface of the adhesive layer (X2) is 0.1 N / 25 mm or more, unintentional peeling from the adherend during temporary fixing, misalignment of the adherend, etc. are more effectively suppressed. be able to. On the other hand, if the adhesive strength is 10.0 N / 25 mm or less, it is easy to peel off without damaging the adherend.

[Shear storage elastic modulus G'(23) of the pressure-sensitive adhesive layer (X2) at 23 ° C.]
The shear storage elastic modulus G'(23) of the pressure-sensitive 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. It is 0 × 10 ⁶ Pa, more preferably 5.0 × 10 ⁴ to 1.0 × 10 ⁶ Pa.
If the shear storage elastic modulus G'(23) of the pressure-sensitive adhesive layer (X2) is 5.0 × 10 ³ Pa or more, the position of the adherend at the time of temporary fixing is displaced, and the pressure-sensitive adhesive layer (X2) of the adherend is There is a tendency to suppress excessive subduction to the water. On the other hand, the shear storage modulus G '(23) is equal to or less than 1.0 × 10 7 ^Pa, there is a tendency to increase adhesion to the adherend.
In the present specification, the shear storage elastic modulus G'(23) of the pressure-sensitive adhesive layer (X2) at 23 ° C. is measured by the same method as the shear storage elastic modulus G'(23) of the pressure-sensitive adhesive layer (X1) at 23 ° C. be able to.

[Thickness of adhesive layer (X2) at 23 ° C]
The thickness of the pressure-sensitive adhesive layer (X2) at 23 ° C. is preferably 5 to 150 μm, more preferably 8 to 100 μm, still more preferably 12 to 70 μm, and even more preferably 15 to 50 μm.
If the thickness of the pressure-sensitive adhesive layer (X2) at 23 ° C. is 5 μm or more, sufficient adhesive strength can be easily obtained, and unintentional peeling from the adherend during temporary fixing, misalignment of the adherend, etc. can occur. It tends to be suppressed. On the other hand, if the thickness of the pressure-sensitive adhesive layer (X2) at 23 ° C. is 150 μm or less, the pressure-sensitive adhesive sheet tends to be easy to handle.

<Release material>
Examples of the release material include a release sheet that has undergone double-sided release treatment, a release sheet that has undergone single-sided release treatment, and the like, in which a release agent is applied onto a base material for the release material.
Examples of the base material for the release material include plastic films and papers. Examples of the plastic film include polyester resin films such as polyethylene terephthalate resin, polybutylene terephthalate resin and polyethylene naphthalate resin; and olefin resin films such as polypropylene resin and polyethylene resin. Examples of papers include high-quality paper. , Glassin paper, kraft paper, etc.

Examples of the release agent include rubber-based elastomers such as silicone-based resins, olefin-based resins, isoprene-based resins, and butadiene-based resins; long-chain alkyl-based resins, alkyd-based resins, and fluorine-based resins. As the release agent, one type may be used alone, or two or more types may be used in combination.

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

[Manufacturing method of adhesive sheet]
In the method for producing a pressure-sensitive adhesive sheet according to one aspect of the present invention, the method for forming the pressure-sensitive adhesive layer (X1) is a polymerizable composition (x-1) containing the energy ray-polymerizable component and the heat-expandable particles. A method for producing an adhesive sheet, which comprises a step of irradiating energy rays to form a polymer of the energy ray-polymerizable component.
The method for forming the pressure-sensitive adhesive layer (X1) preferably includes the following steps I and II.
Step I: Forming a polymerizable composition layer composed of the polymerizable composition (x-1) on one surface side of the base material (Y) Step II: Irradiating the polymerizable composition layer with energy rays. As a result, a step of forming a polymer of the energy ray-polymerizable component and forming a pressure-sensitive adhesive layer (X1) containing the polymer and the heat-expandable particles.

<Process I>
The step I is not particularly limited as long as it is a step of forming the polymerizable composition layer on one surface side of the base material (Y), but it is preferable to include the following steps I-1 to I-3.
Step I-1: A step of applying the polymerizable composition (x-1) on the peeling surface of the release material to form a polymerizable composition layer. Step I-2: With respect to the above-mentioned polymerizable composition layer. Step I-3: A step of prepolymerizing the energy ray-polymerizable component in the polymerizable composition layer by irradiating the first energy ray. Step I-3: A base material (Y) is applied to the polymerizable composition layer after the first energy ray irradiation. Process of pasting

(Step I-1)
Step I-1 is a step of applying the polymerizable composition (x-1) on the peeling surface of the release material to form the polymerizable composition layer.
In step I-1, the method of applying the polymerizable composition (x-1) to the release material includes, for example, a spin coating method, a spray coating method, a bar coating method, a knife coating method, a roll coating method, and a blade coating method. , Die coat method, gravure coat method and the like.

As described above, the polymerizable composition (x-1) is preferably a solvent-free polymerizable composition. When the polymerizable composition (x-1) is a solvent-free polymerizable composition, it is not necessary to carry out the solvent heating and drying step in this step. On the other hand, when the polymerizable composition (x-1) contains a solvent within a range not contrary to the object of the present invention, the polymerizable composition (x-1) may be applied and then heat-dried. In that case, the heating temperature is lower than the expansion start temperature (t) of the thermally expandable particles.

(Step I-2)
Step I-2 is a step of irradiating the polymerizable composition layer formed in step I-1 with the first energy ray to prepolymerize the energy ray-polymerizable component in the polymerizable composition layer. ..
The first energy ray irradiation is carried out for the purpose of increasing the viscosity of the polymerizable composition by prepolymerizing the energy ray-polymerizable component and improving the shape retention of the polymerizable composition layer.
In the first energy ray irradiation, the energy ray-polymerizable component is not completely polymerized, but only prepolymerized. This makes it possible to improve the adhesion between the polymerizable composition layer and the base material (Y) in step I-3.

Among the above-mentioned energy rays, ultraviolet rays, which are easy to handle, are preferable as the energy rays used for the first energy ray irradiation in step I-2.
Illuminance of ultraviolet in the first energy beam irradiation is preferably 70 ~ 250mW / cm ^2, more preferably 100 ~ 200mW / cm ^2, more preferably 130 ~ 170mW / cm ^2. Further, the amount of ultraviolet in the first energy beam irradiation is preferably 40 ~ 200mJ / cm ^2, more preferably 60 ~ 150mJ / cm ^2, more preferably 80 ~ 120mJ / cm ^2.
The first energy ray irradiation may be performed once or may be divided into a plurality of times. Further, in order to suppress the temperature rise of the polymerizable composition layer due to the heat of polymerization or the like, the polymerizable composition layer may be cooled.

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

<Process II>
In step II, the polymerizable composition layer formed in step I is irradiated with energy rays to form a polymer of energy ray-polymerizable components, and a pressure-sensitive adhesive layer containing the polymer and heat-expandable particles. This is a step of forming (X1).

Here, when the first energy ray irradiation is performed in the step I, the energy ray irradiation in the step II is the second energy ray irradiation performed on the polymerizable composition layer after the prepolymerization.
The energy ray irradiation in step II is different from the first energy ray irradiation, and it is preferable that the energy ray irradiation is performed to such an extent that the polymerization of the energy ray-polymerizable component does not substantially proceed even if the energy rays are further irradiated.
By the energy ray irradiation in step II, the polymerization of the energy ray-polymerizable component proceeds, and the polymer of the energy ray-polymerizable component constituting the pressure-sensitive adhesive layer (X1) is formed.

Among the above-mentioned energy rays, ultraviolet rays, which are easy to handle, are preferable as the energy rays used for the energy ray irradiation in step II.
Illuminance of ultraviolet in the energy beam irradiation step II is preferably 100 ~ 350mW / cm ^2, more preferably 150 ~ 300mW / cm ^2, more preferably 180 ~ 250mW / cm ^2.
Quantity of ultraviolet light in the energy beam irradiation step II is preferably 500 ~ 4,000mJ / cm ^2, more preferably 1,000 ~ 3,000mJ / cm ^2, more preferably 1,500 ~ 2,500mJ / cm ² Is.
The energy ray irradiation in step II may be performed once or may be performed in multiple times. Further, in order to suppress the temperature rise of the polymerizable composition layer due to the heat of polymerization or the like, the polymerizable composition layer may be cooled.

When the step I includes the above steps I-1 to I-3, the polymerizable composition layer is intermediate between the release material, the polymerizable composition layer, and the base material (Y) laminated in this order. Obtained as a layer. At this time, the second energy ray irradiation may be performed on the laminated body having the said structure. In that case, one or more selected from the release material and the base material (Y) are energy from the viewpoint of making it possible to sufficiently irradiate the polymerizable composition layer existing as the intermediate layer of the laminate with energy rays. Those having line transparency are preferable.

In any of the steps included in the above steps I and II, it is preferable not to include a step of heating the polymerizable composition from the viewpoint of suppressing the expansion of the heat-expandable particles.
The term "heating" here means, for example, intentionally heating during drying, laminating, etc., and the heat and energy ray-polymerizable composition imparted to the polymerizable composition by irradiation with energy rays. The temperature rise due to the heat of polymerization generated by polymerization is not included.
When the step of heating the polymerizable composition as required is included, the heating temperature is preferably "a temperature lower than the expansion start temperature (t)", more preferably "expansion start temperature (t) -5 ° C." or less. It is more preferably "expansion start temperature (t) -10 ° C." or less, and even more preferably "expansion start temperature (t) -15 ° C." or less. When the temperature of the polymerizable composition rises unintentionally, it is preferable to cool the polymerizable composition so that the temperature falls within the above temperature range.

When the pressure-sensitive adhesive sheet according to one aspect of the present invention has the structure of the double-sided pressure-sensitive adhesive sheet, the method for producing the pressure-sensitive adhesive sheet according to one aspect of the present invention preferably further includes the following step III.

<Process III>
Step III: A step of forming an adhesive layer (X2) on the other surface side of the base material (Y).

The method for forming the pressure-sensitive adhesive layer (X2) may be appropriately determined according to the type of the composition constituting the pressure-sensitive adhesive layer (X2). For example, when the pressure-sensitive adhesive layer (X2) is formed by using the pressure-sensitive adhesive composition (x-2), step III preferably includes the following steps III-1 and III-2.
Step III-1: A step of applying the pressure-sensitive adhesive composition (x-2) to one surface of the release material to form a pressure-sensitive adhesive layer (X2) Step III-2: The other side of the base material (Y) The step of attaching the adhesive layer (X2) formed in step III-1 to

As a method for applying the pressure-sensitive adhesive composition (x-2) in step III-1, the same method as that mentioned as a method for applying the polymerizable composition (x-1) in step I-1 can be mentioned. Be done. When the pressure-sensitive adhesive layer (X2) contains a solvent, it may include a step of applying the pressure-sensitive adhesive composition (x-2) and then drying the coating film.
As described above, the release material used in step III-1 and the release material used in step I-1 suppress the phenomenon that the pressure-sensitive adhesive layer is separated and peeled off by the two release materials. From the viewpoint, it is preferable that the peeling force is designed to be different.

As a method of attaching the pressure-sensitive adhesive layer (X2) to the base material (Y) in step III-2, the same method as the method of attaching the base material (Y) to the polymerizable composition layer in step I-3 can be mentioned. The same applies to the preferred embodiments.

[Use and usage of adhesive sheet]
The pressure-sensitive adhesive sheet according to one aspect of the present invention can be heat-peeled at a low temperature while having sufficient adhesive strength at the time of temporary fixing, and therefore can be applied to various uses. Specifically, for example, a dicing sheet used when dicing an adherend such as a semiconductor wafer, a back grind sheet used in a process of grinding an adherend, a substrate such as a semiconductor chip individualized by dicing. Expanding tape used to increase the distance between wafers, transfer tape used to invert the front and back of adherends such as semiconductor chips, and temporary fixing used to temporarily fix an object to be inspected. Suitable for fixing sheets and the like.

The adherend of the pressure-sensitive adhesive sheet according to one aspect of the present invention is not particularly limited, and examples thereof include semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, sapphire substrates, displays, and panel substrates. Since the pressure-sensitive adhesive sheet of one aspect of the present invention can be peeled off by heating at a low temperature, it is suitable for temporarily fixing an adherend that easily changes heat, such as a semiconductor chip with DAF.

The heating temperature at which the pressure-sensitive adhesive sheet according to one aspect of the present invention is heat-peeled from the adherend is equal to or higher than the expansion start temperature (t) of the heat-expandable particles, and is preferably “a temperature higher than the expansion start temperature (t)”. , More preferably "expansion start temperature (t) + 2 ° C." or higher, further preferably "expansion start temperature (t) + 4 ° C." or higher, and even more preferably "expansion start temperature (t) + 5 ° C." or higher. Further, from the viewpoint of energy saving and suppressing the thermal change of the adherend at the time of heat peeling, it is preferably "expansion start temperature (t) + 50 ° C." or less, more preferably "expansion start temperature (t) + 40 ° C." or less. More preferably, it is "expansion start temperature (t) + 20 ° C." or less.
Further, the heating temperature at the time of heat peeling is preferably 120 ° C. or lower, more preferably 115 ° C. or lower, and further, within the range of the expansion start temperature (t) or higher, from the viewpoint of suppressing the thermal change of the adherend. It is preferably 110 ° C. or lower, and even more preferably 105 ° C. or lower.

The heating method is not particularly limited as long as it can be heated to a temperature higher than the temperature at which the thermally expandable particles expand, and for example, an electric heater; dielectric heating; magnetic heating; near infrared rays, mid infrared rays, far infrared rays, etc. Heating by electromagnetic waves such as infrared rays can be appropriately used. The heating method may be any of a contact type heating method such as a heating roller and a heating press, and a non-contact type heating method such as an atmosphere heating device and infrared irradiation.

[Manufacturing method of semiconductor devices]
The present invention also provides a method for manufacturing a semiconductor device using the pressure-sensitive adhesive sheet according to one aspect of the present invention.
As one aspect of the method for manufacturing a semiconductor device of the present invention, the adhesive sheet of one aspect of the present invention is used as a temporary fixing sheet for processing an adherend (hereinafter, "the semiconductor device of the first aspect"). Also referred to as "manufacturing method").

<Manufacturing method of semiconductor device of the first aspect>
As a more specific aspect of the method for manufacturing a semiconductor device of the first aspect, a work object is attached to the pressure-sensitive adhesive sheet of one aspect of the present invention, and the work object is subjected to a grinding process and an individualization process. One or more selected treatments (hereinafter, also referred to as "processing treatments") are performed, and after the treatments, the pressure-sensitive adhesive sheet is heated to 120 ° C. or higher at the expansion start temperature (t) or higher to obtain a pressure-sensitive adhesive layer. Examples thereof include a method for manufacturing a semiconductor device, which includes a step of expanding (X1).
In addition, in this specification, a "semiconductor device" refers to a device in general that can function by utilizing semiconductor characteristics. For example, wafers with integrated circuits, thinned wafers with integrated circuits, chips with integrated circuits, thinned chips with integrated circuits, electronic components including these chips, and electronic components with the electronic components. Kind and the like.

In the method for manufacturing a semiconductor device of the first aspect, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet to which the object to be processed is attached may be the pressure-sensitive adhesive layer (X1), and when the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, the pressure-sensitive adhesive It may be a layer (X2).
When the pressure-sensitive adhesive sheet is a double-sided pressure-sensitive adhesive sheet, it is preferable that the object to be processed is attached to one pressure-sensitive adhesive layer and the support is attached to the other pressure-sensitive adhesive layer. By fixing the object to be processed to the support via the adhesive sheet, vibration, misalignment, damage to the fragile object to be processed, etc. can be suppressed during the processing, and the processing accuracy and processing can be improved. The speed can be improved. At this time, the support may be attached to the pressure-sensitive adhesive layer (X1) and the object to be processed may be attached to the pressure-sensitive adhesive layer (X2), or the object to be processed may be attached to the pressure-sensitive adhesive layer (X1). The support may be attached to the pressure-sensitive adhesive layer (X2).
When the support is attached to the pressure-sensitive adhesive layer (X1) and the object to be processed is attached to the pressure-sensitive adhesive layer (X2), the support is attached to the pressure-sensitive adhesive layer (X1) having excellent peelability after heat treatment. By being attached, even if the support is made of a hard material, the adhesive sheet and the support can be heat-peeled without bending. Further, the composition of the pressure-sensitive adhesive layer (X2) may be appropriately selected according to the type of the object to be processed, and for example, the pressure-sensitive adhesive layer (X2) is a pressure-sensitive adhesive layer whose adhesive strength is reduced by irradiation with energy rays. , The object to be processed can be peeled off without being contaminated by the residue derived from the thermally expandable particles.
On the other hand, when the object to be processed is attached to the pressure-sensitive adhesive layer (X1) and the support is attached to the pressure-sensitive adhesive layer (X2), the object to be processed is a pressure-sensitive adhesive layer having excellent peelability after heat treatment (X1). By being attached to X1), when the object to be processed is peeled off by heating after processing, the object to be processed can be peeled from the adhesive sheet by self-peeling, so that damage to the object to be processed can be reduced.

When a double-sided pressure-sensitive adhesive sheet is used as the pressure-sensitive adhesive sheet of one aspect of the present invention, the method for manufacturing the semiconductor device of the first aspect is a manufacturing method including the following steps 1A to 5A (hereinafter, also referred to as "manufacturing method A"). Is preferable.
Step 1A: A process of attaching the object to be processed to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet and attaching a support to the pressure-sensitive adhesive layer (X1) Step 2A: Grinding and individual pieces of the object to be processed. Step 3A of applying one or more treatments selected from the chemical treatment: Step 4A of attaching a thermosetting film to the surface of the processed object to be treated, which is opposite to the pressure-sensitive adhesive layer (X2). : A step of heating the pressure-sensitive adhesive sheet to 120 ° C. or higher and the expansion start temperature (t) or more to separate the pressure-sensitive adhesive layer (X1) from the support Step 5A: The pressure-sensitive adhesive layer (X2) and the processing target The process of separating things

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, an example in which a semiconductor wafer is used as a processing object will be mainly described, but the same applies to other processing objects.

(Step 1A)
Step 1A is a step of attaching the object to be processed to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet and attaching the support to the pressure-sensitive adhesive layer (X1).
FIG. 3 is a cross-sectional view illustrating a step of attaching the semiconductor wafer W to the adhesive layer (X2) of the adhesive sheet 2b and attaching the support 3 to the adhesive layer (X1).
The semiconductor wafer W is attached so that the surface W1 which is the circuit surface is on the adhesive layer (X2) side.
The semiconductor wafer W may be a silicon wafer, a wafer such as gallium arsenide, silicon carbide, sapphire, lithium tantalate, lithium niobate, gallium nitride, indium phosphorus, or a glass wafer.
The thickness of the semiconductor wafer W before grinding is usually 500 to 1000 μm.
The circuit included in the surface W1 of the semiconductor wafer W can be formed by, for example, a conventionally used general-purpose method such as an etching method or a lift-off method.

The material of the support 3 may be appropriately selected in consideration of required characteristics such as mechanical strength and heat resistance according to the type of the object to be processed, the content of processing, and the like.
Examples of the material of the support 3 include metal materials such as SUS; non-metallic inorganic materials such as glass and silicon wafers; epoxy resin, ABS resin, acrylic resin, engineering plastic, super engineering plastic, polyimide resin, polyamideimide resin and the like. Resin materials: Composite materials such as glass epoxy resin, and among these, SUS, glass, and silicon wafers are preferable.
Examples of the engineering plastic include nylon, polycarbonate (PC), polyethylene terephthalate (PET), and the like.
Examples of the super engineering plastic include polyphenylene sulfide (PPS), polyethersulfone (PES), and polyetheretherketone (PEEK).

The support 3 is preferably attached to the entire surface of the adhesive surface of the adhesive layer (X1). Therefore, the area of the surface of the support 3 on the side to be attached to the adhesive surface of the adhesive layer (X1) is preferably equal to or larger than the area of the adhesive surface of the adhesive layer (X1). Further, it is preferable that the surface of the support 3 on the side to be attached to the adhesive surface of the adhesive layer (X1) is flat.
The shape of the support 3 is not particularly limited, but is preferably plate-shaped.
The thickness of the support 3 may be appropriately selected in consideration of the required characteristics, but is preferably 20 μm or more and 50 mm or less, and more preferably 60 μm or more and 20 mm or less.

(Step 2A)
Step 2A is a step of performing one or more processes selected from a grinding process and an individualizing process on the object to be processed.
As one or more processes selected from the grinding process and the individualization process, for example, a grinding process using a grinder or the like; a blade dicing method, a laser dicing method, a stealth dicing (registered trademark) method, a blade tip dicing method, a stealth tip Individualization processing by a dicing method or the like can be mentioned.
Among these, individualization treatment by stealth dicing method, grinding treatment and individualization treatment by blade tip dicing method, grinding treatment and individualization treatment by stealth tip dicing method are preferable, and grinding treatment by blade tip dicing method. And individualization treatment, grinding treatment by stealth tip dicing method and individualization treatment are more preferable.

The stealth dicing method is a method in which a modified region is formed inside a semiconductor wafer by irradiation with laser light, and the semiconductor wafer is individualized using the modified region as a division starting point. The modified region formed on the semiconductor wafer is a portion that has been made brittle by multiphoton absorption, and the modified region is applied by applying stress in the direction in which the semiconductor wafer is parallel to the wafer surface and the wafer is expanded due to expansion. The cracks extend toward the front surface and the back surface of the semiconductor wafer starting from the above, and are separated into semiconductor chips. That is, the modified region is formed along the dividing line when it is individualized.
The modified region is formed inside the semiconductor wafer by irradiation with a laser beam focused on the inside of the semiconductor wafer. The incident surface of the laser beam may be the front surface or the back surface of the semiconductor wafer. Further, the laser beam incident surface may be a surface to which the adhesive sheet is attached, in which case the laser beam is applied to the semiconductor wafer via the adhesive sheet.

The blade tip dicing method is also called the DBG method (Dicing Before Grinding). In the blade tip dicing method, a groove is formed in the semiconductor wafer in advance along the line to be divided at a depth shallower than the thickness, and then the semiconductor wafer is back-ground to be thin until the ground surface reaches at least the groove. It is a method of individualizing while making it. The groove reached by the ground surface becomes a notch penetrating the semiconductor wafer, and the semiconductor wafer is divided by the notch and separated into semiconductor chips. The pre-formed groove is usually provided on the surface (circuit surface) of the semiconductor wafer, and can be formed by dicing using, for example, a conventionally known wafer dicing device provided with a dicing blade.

The stealth dicing method is also called the SDBG method (Stealth Dicing Before Grinding). Similar to the stealth dicing method, the stealth dicing method is a kind of method in which a modified region is formed inside the semiconductor wafer by irradiation with laser light, and the semiconductor wafer is individualized using the modified region as a division starting point. However, it differs from the stealth dicing method in that the semiconductor wafer is fragmented into semiconductor chips while thinning the semiconductor wafer by grinding. Specifically, while the semiconductor wafer having the modified region is back-ground to be thinned, the pressure applied to the semiconductor wafer at that time causes the modified region as a starting point to be directed toward the surface to be attached to the pressure-sensitive adhesive layer of the semiconductor wafer. The cracks are extended and the semiconductor wafer is separated into semiconductor chips.
The grinding thickness after forming the reformed region may be the thickness reaching the reformed region, but even if it does not reach the reformed region strictly, it is ground to a position close to the reformed region. Then, it may be split by the processing pressure of a grinding wheel or the like.

When the semiconductor wafer W is individualized by the blade tip dicing method, it is preferable that a groove is formed in advance on the surface W1 of the semiconductor wafer W to be attached to the pressure-sensitive adhesive layer (X2) in step 1A.
On the other hand, when the semiconductor wafer W is individualized by the stealth tip dicing method, the semiconductor wafer W to be attached to the pressure-sensitive adhesive layer (X2) is irradiated with laser light in step 1A to form a modified region in advance. Alternatively, the semiconductor wafer W attached to the pressure-sensitive adhesive layer (X2) may be irradiated with a laser beam to form a modified region.

FIG. 4 shows a cross-sectional view illustrating a step of forming a plurality of reformed regions 5 on the semiconductor wafer W attached to the pressure-sensitive adhesive layer (X2) by using the laser light irradiation device 4.
The laser beam is irradiated from the back surface W2 side of the semiconductor wafer W, and a plurality of modified regions 5 are formed inside the semiconductor wafer W at substantially equal intervals.

In FIG. 5, a plurality of semiconductor chip CPs while thinning the semiconductor wafer W by grinding the back surface W2 of the semiconductor wafer W on which the modified region 5 is formed by a grinder 6 and dividing the semiconductor wafer W starting from the modified region 5 A cross-sectional view illustrating the process of individualizing is shown.
In the semiconductor wafer W on which the modified region 5 is formed, for example, the back surface W2 of the semiconductor wafer W is ground in a state where the support 3 supporting the semiconductor wafer W is fixed on a fixed table such as a chuck table.

The thickness of the semiconductor chip CP after grinding is preferably 5 to 100 μm, more preferably 10 to 45 μm. Further, when the grinding process and the individualization process are performed by the stealth tip dicing method, the thickness of the semiconductor chip CP obtained by grinding can be easily set 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 . In addition, the plan view means to see in the thickness direction.
The shape of the semiconductor chip CP after fragmentation in a plan view may be a rectangular shape or an elongated shape such as a rectangle.

(Step 3A)
Step 3A is a step of attaching a thermosetting film to the surface of the processed object to be processed, which is opposite to the pressure-sensitive adhesive layer (X2).
FIG. 6 illustrates a step of attaching a thermosetting film 7 provided with a support sheet 8 to a surface of a plurality of semiconductor chip CPs obtained by performing the above treatment on a surface opposite to the pressure-sensitive adhesive layer (X2). A cross-sectional view is shown.

The thermosetting film 7 is a film having thermosetting property obtained by forming a resin composition containing at least a thermosetting resin, and is used as an adhesive when mounting a semiconductor chip CP on a substrate. The thermosetting film 7 may contain a curing agent for the thermosetting resin, a thermoplastic resin, an inorganic filler, a curing accelerator, and the like, if necessary.
As the thermosetting film 7, for example, a thermosetting film generally used as a die bonding film, a die attach film, or the like can be used.
The thickness of the thermosetting film 7 is not particularly limited, but is usually 1 to 200 μm, preferably 3 to 100 μm, and more preferably 5 to 50 μm.
The support sheet 8 may be any as long as it can support the thermosetting film 7, and examples thereof include resins, metals, and paper materials listed as the base material (Y) contained in the pressure-sensitive adhesive sheet according to the present invention. ..

Examples of the method of attaching the thermosetting film 7 to a plurality of semiconductor chip CPs include a method of laminating.
Laminating may be performed while heating or may be performed without heating. When the lamination is performed while heating, the heating temperature is preferably "a temperature lower than the expansion start temperature (t)" from the viewpoint of suppressing the expansion of the thermally expandable particles and suppressing the thermal change of the adherend. It is preferably "expansion start temperature (t) -5 ° C." or less, more preferably "expansion start temperature (t) -10 ° C." or less, and even more preferably "expansion start temperature (t) -15 ° C." or less.

(Step 4A)
Step 4A is a step of heating the pressure-sensitive adhesive sheet to 120 ° C. or higher at the expansion start temperature (t) or higher to separate the pressure-sensitive adhesive layer (X1) from the support.
FIG. 7 shows a cross-sectional view illustrating a step of heating the pressure-sensitive adhesive sheet 2b to separate the pressure-sensitive adhesive layer (X1) and the support 3.

The heating temperature in step 4A is equal to or higher than the expansion start temperature (t) of the thermally expandable particles, and is preferably "a temperature higher than the expansion start temperature (t)", more preferably "expansion start temperature" in the range of 120 ° C. or lower. (T) + 2 ° C. "or higher, more preferably" expansion start temperature (t) + 4 ° C. "or higher, and even more preferably" expansion start temperature (t) + 5 ° C. " Further, the heating temperature in step 4A is preferably "expansion start temperature (t) + 50 ° C." or less in the range of 120 ° C. or lower from the viewpoint of energy saving and suppressing the thermal change of the adherend at the time of heat peeling. It is preferably "expansion start temperature (t) + 40 ° C." or less, and more preferably "expansion start temperature (t) + 20 ° C." or less.
From the viewpoint of suppressing the thermal change of the adherend, the heating temperature in the step 4A is preferably 115 ° C. or lower, more preferably 110 ° C. or lower, still more preferably 105 ° C. within the range of the expansion start temperature (t) or higher. It is as follows.

(Step 5A)
Step 5A is a step of separating the pressure-sensitive adhesive layer (X2) from the object to be processed.
FIG. 8 shows a cross-sectional view illustrating a step of separating the pressure-sensitive adhesive layer (X2) and the plurality of semiconductor chip CPs.
The method for separating the pressure-sensitive adhesive layer (X2) and the plurality of semiconductor chip CPs may be appropriately selected according to the type of the pressure-sensitive adhesive layer (X2). For example, when the pressure-sensitive adhesive layer (X2) is a pressure-sensitive adhesive layer whose adhesive strength is reduced by irradiation with energy rays, the pressure-sensitive adhesive layer (X2) is irradiated with energy rays to reduce the adhesive strength and then separated. do it.

Through the above steps 1A to 5A, a plurality of semiconductor chip CPs attached on the thermosetting film 7 can be obtained.
Next, it is preferable to divide the thermosetting film 7 to which the plurality of semiconductor chip CPs are attached into the same shape as the semiconductor chip CP to obtain the semiconductor chip CP with the thermosetting film 7. As a method for dividing the thermosetting film 7, for example, a method such as laser dicing with laser light, expanding, or fusing 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 further includes an expanding step of widening the distance between the semiconductor chip CPs, a rearrangement step of arranging a plurality of semiconductor chip CPs having a wide distance, and a plurality of semiconductor chip CPs, if necessary. After an appropriate inversion step of inverting the front and back of the above, the thermosetting film 7 is attached (diatached) to the substrate from the side. After that, the semiconductor chip and the substrate can be fixed by thermosetting the thermosetting film.

The production method according to one aspect of the present invention may not include step 3A in the production method A. When the step 3A is not included, the following step 4A'may be included instead of the step 4A.
Step 4A': A step of heating the pressure-sensitive adhesive sheet to the expansion start temperature (t) or higher to separate the pressure-sensitive adhesive layer (X1) from the support.

When a double-sided pressure-sensitive adhesive sheet is used as the pressure-sensitive adhesive sheet of one aspect of the present invention, the method for manufacturing the semiconductor device of the first aspect is a manufacturing method including the following steps 1B to 4B (hereinafter, also referred to as "manufacturing method B"). May be good.
Step 1B: A process of attaching the object to be processed to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet, and attaching a support to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet. Step of performing one or more treatments selected from grinding treatment and individualization treatment Step 3B: Thermocurability is applied to the surface of the processed object to which the treatment has been performed, which is opposite to the pressure-sensitive adhesive layer (X1). Step 4B: A step of heating the pressure-sensitive adhesive sheet to 120 ° C. or higher above the expansion start temperature (t) to separate the pressure-sensitive adhesive layer (X1) from the object to be processed.

Steps 1B to 3B are described by replacing the pressure-sensitive adhesive layer (X1) with the pressure-sensitive adhesive layer (X2) and the pressure-sensitive adhesive layer (X2) with the pressure-sensitive adhesive layer (X1) in the description of steps 1A to 3A. ..

Step 4B is a step of heating the pressure-sensitive adhesive sheet to 120 ° C. or higher at the expansion start temperature (t) or higher to separate the pressure-sensitive adhesive layer (X1) from the object to be processed.
The heating conditions such as the heating temperature of the pressure-sensitive adhesive sheet in step 4B are the same as those described in step 4A.
By step 4B, a plurality of semiconductor chips attached on the thermosetting film are obtained. Then, as in the case of the manufacturing method A described above, the thermosetting film is divided to obtain a semiconductor chip with a thermosetting film.

The manufacturing method B may include a step 5B for separating the pressure-sensitive adhesive layer (X2) and the support after the step 4B.
The method for separating the pressure-sensitive adhesive layer (X2) and the support may be appropriately selected according to the type of the pressure-sensitive adhesive layer (X2). For example, when the pressure-sensitive adhesive layer (X2) is a pressure-sensitive adhesive layer whose adhesive strength is reduced by irradiation with energy rays, the pressure-sensitive adhesive layer (X2) is irradiated with energy rays to reduce the adhesive strength and then separated. do it.

The production method of one aspect of the present invention may not include step 3B in the production method B. When step 3B is not included, the following step 4B'may be included instead of step 4B.
Step 4B': A step of heating the pressure-sensitive adhesive sheet to the expansion start temperature (t) or higher to separate the pressure-sensitive adhesive layer (X1) from the object to be processed.

<Manufacturing method of semiconductor device of another aspect>
The method for manufacturing a semiconductor device of the present invention is not limited to the method for manufacturing a semiconductor device according to the first aspect described above, and may be a method for manufacturing a semiconductor device according to another aspect from the first aspect.
As an example of the method for manufacturing a semiconductor device of another aspect, there is a method of using the pressure-sensitive adhesive sheet of one aspect of the present invention as a temporary fixing sheet for inspecting an inspection object as a part of a manufacturing process. Examples of the inspection performed on the inspection object include a defect inspection using an optical microscope and a laser (for example, dust inspection, surface scratch inspection, wiring pattern inspection, etc.), and a visual surface inspection.
Examples of the inspection target include semiconductor chips, semiconductor wafers, compound semiconductors, semiconductor packages, electronic components, LED elements, sapphire substrates, displays, panel substrates, and the like.
When the adhesive sheet of one aspect of the present invention is used as a temporary fixing sheet for inspecting an inspection object, the inspection is carried out with a plurality of inspection objects attached to the adhesive layer (X1) of the adhesive sheet. Can be carried out. After performing the inspection, for example, a part of the pressure-sensitive adhesive layer (X1) to which the plurality of inspection objects are attached is locally heated to obtain a specific inspection object attached to the portion. It can also be selectively heat-peeled. At this time, since the pressure-sensitive adhesive sheet according to one aspect of the present invention can be heat-peeled at a low temperature, it is excellent in workability and energy saving of the heat-peeling work, and even if the inspection object is easily thermally changed. , It is possible to suppress the thermal change of the inspection object due to heating at the time of heat peeling.

As another example of the method for manufacturing a semiconductor device of another aspect, there is a method of separating an object to be processed attached to another sheet from the other sheet by using the adhesive sheet of one aspect of the present invention. Can be mentioned.
For example, a plurality of semiconductor chips that are spaced apart on the expanding tape are attached to the adhesive surface of the expanding tape, but the work of picking up these chips one by one is complicated. According to the method for manufacturing a semiconductor device according to one aspect of the present invention, the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet according to one aspect of the present invention is attached to the exposed surface of a plurality of semiconductor chips attached on the expanding tape, and then. By peeling the expanding tape from the plurality of semiconductor chips, the plurality of semiconductor chips can be separated from the expanding tape at once.
Through the above steps, a plurality of semiconductor chips attached on the pressure-sensitive adhesive sheet according to one aspect of the present invention can be obtained. The plurality of semiconductor chips can be easily separated by subsequently heating the pressure-sensitive adhesive layer (X1) to a temperature equal to or higher than the expansion start temperature (t) of the heat-expandable particles. At this time, since the pressure-sensitive adhesive sheet according to one aspect of the present invention can be heat-peeled at a low temperature, it is excellent in workability and energy saving of heat-peeling work, and even if the adherend is easily thermally changed. , It is possible to suppress the thermal change of the adherend due to heating at the time of heat peeling.
The plurality of separated semiconductor chips may be transferred to another pressure-sensitive adhesive sheet, or may be subjected to a rearrangement step of aligning the plurality of semiconductor chips after being separated once.

The present invention will be specifically described with reference to the following examples, but the present invention is not limited to the following examples.
In the following description, the "non-expandable pressure-sensitive adhesive layer (X1')" means a pressure-sensitive adhesive layer that does not contain heat-expandable particles, and is the same as the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet produced in the comparative example described later. The pressure-sensitive adhesive layer containing no heat-expandable particles prepared for the measurement of the coefficient of thermal expansion G'corresponds to the non-expandable pressure-sensitive adhesive layer (X1').
The physical property values in the following synthesis examples and examples are values measured by the following methods.

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

[Thickness of each layer]
The measurement was performed using a constant pressure thickness measuring instrument (model number: "PG-02J", standard: JIS K6783, Z1702, Z1709 compliant) manufactured by Teclock Co., Ltd.

[Average particle size of thermally expandable particles (D ₅₀ ), 90% particle size (D ₉₀ )]
The particle distribution of the thermally expandable particles before expansion at 23 ° C. was measured using a laser diffraction type particle size distribution measuring device (for example, manufactured by Malvern, product name “Master Sizar 3000”).
Then, the particle diameters corresponding to the cumulative volume frequencies of 50% and 90% calculated from the smaller particle diameter of the particle distribution are set to "average particle diameter of thermally expandable particles (D ₅₀ )" and "thermally expandable particles", respectively. 90% particle size (D ₉₀ ) ”.

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

[Shear storage elastic modulus G'(23) of the pressure-sensitive adhesive layer (X1) at 23 ° C.]
A test sample having a pressure-sensitive adhesive layer (X1) having a diameter of 8 mm and a thickness of 3 mm was used as a test sample, and a viscoelasticity measuring device (manufactured by Antonio Par Co., Ltd., device name “MCR300”) was used to set a test start temperature of 0 ° C. and a test end temperature. The shear storage elastic modulus G'(23) at 23 ° C. was measured by the torsional shearing method under the conditions of 300 ° C., a heating rate of 3 ° C./min, and a frequency of 1 Hz.

[Shear storage elastic modulus G'of non-expandable pressure-sensitive adhesive layer (X1')]
In order to measure the shear storage elastic modulus G'excluding the influence of the heat-expandable particles, in each example, the non-expansion has the same structure as the pressure-sensitive adhesive layer (X1) except that the heat-expandable particles are not contained. The pressure-sensitive adhesive layer (X1') was prepared as a sample for measuring the shear storage elastic modulus corresponding to the pressure-sensitive adhesive layer (X1) of each example, and the shear storage elastic modulus G'was measured.
The shear storage elastic modulus G'of the non-expandable pressure-sensitive adhesive layer (X1') prepared in Comparative Example was also measured by this evaluation method.
A test sample having a non-expandable pressure-sensitive adhesive layer (X1') having a diameter of 8 mm and a thickness of 3 mm was used as a test sample, and a test start temperature of 0 ° C. was used using a viscoelasticity measuring device (manufactured by Antonio Par, device name "MCR300"). The shear storage elastic modulus G'(23) at 23 ° C. and the expansion start temperature of the thermally expandable particles (23 ° C.) under the conditions of the test end temperature of 300 ° C., the heating rate of 3 ° C./min, and the frequency of 1 Hz by the torsional shear method. The shear storage elastic modulus G'(t) at t) was measured.
The expansion start temperature (t) of the heat-expandable particles of the non-expandable pressure-sensitive adhesive layer (X1'), which is a sample for measuring the shear storage elastic modulus, is the adhesion of the example corresponding to the sample for measuring the shear storage elastic modulus. It means the expansion start temperature (t) of the heat-expandable particles contained in the agent layer (X1), and in this example, it means 88 ° C. as described later.
Moreover, since the pressure-sensitive adhesive sheet produced in Comparative Example did not have the expansion start temperature (t), the shear storage elastic modulus G'at 88 ° C., which was the same as in Example, was measured.

Synthesis example 1
(Synthesis of urethane acrylate-based prepolymer)
100 parts by mass of polypropylene glycol having a mass average molecular weight (Mw) of 3,000 (solid content conversion value; the same applies hereinafter), 4 parts by mass of hexamethylene diisocyanate, and 0.02 parts by mass of dioctyltin dilaurate are mixed and at 80 ° C. The reaction product (hereinafter, also referred to as “unmodified prepolymer”) was obtained by stirring for 6 hours. When the IR spectrum of the obtained reaction product was measured by infrared spectroscopy, it was confirmed that the isocyanate groups had almost disappeared.
Then, 1 part by mass of 2-isocyanate ethyl acrylate was mixed with the total amount of the obtained reaction product, and the mixture was stirred at 80 ° C. for 3 hours to obtain a urethane acrylate-based prepolymer. When the IR spectrum of the obtained urethane acrylate-based prepolymer was measured by infrared spectroscopy, it was confirmed that the isocyanate groups had almost disappeared. The mass average molecular weight (Mw) of the obtained urethane acrylate-based prepolymer was 25,000.

Examples 1-22
(Production of polymerizable composition)
Each component shown in Table 1 was mixed with the compounding composition shown in Table 1 to obtain a solvent-free polymerizable composition.
The details of each component shown in Table 1 are as follows.
[Polymerizable vinyl monomer]
2EHA: 2-Ethylhexyl acrylate ((a1-1) component)
IBXA: Isobornyl acrylate ((a1-2) component)
HEA: 2-hydroxyethyl acrylate ((a1-3) component)
4HBA: 4-Hydroxybutyl acrylate ((a1-3) component)
[Polyfunctional (meth) acrylate monomer]
Trifunctional monomer: Ethylene oxide-modified triacrylate of isocyanuric acid ((a1-4) component)
[Polyfunctional (meth) acrylate prepolymer]
Urethane acrylate-based prepolymer: prepared in Synthesis Example 1 (component (a2))
Polyacrylic acrylate-based prepolymer: "KANEKA XMAP (registered trademark) RC100C" (manufactured by Kaneka Corporation, polyacrylic prepolymer having acryloyl groups at both ends, mass average molecular weight (Mw): 21,500) ((a2) component)
[Photopolymerization initiator]
1-Hydroxycyclohexylphenyl ketone [heat-expandable particles]
Made by AkzoNobel, product name "Expancel (registered trademark) 031-40" (DU type), expansion start 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 the pressure-sensitive adhesive layer (X1) or the non-expandable pressure-sensitive adhesive layer (X1')" in Table 1 means that the component was not blended.

(Manufacturing of adhesive sheet)
Using the solvent-free polymerizable composition produced above, an adhesive sheet was produced by the following procedure.
The solvent-free polymerizable composition is applied onto the peeling surface of a polyethylene terephthalate (PET) -based release film (manufactured by Lintec Corporation, product name "SP-PET38131", thickness: 38 μm) to be applied to the polymerizable composition layer. Was formed. The polymerizable composition layer was prepolymerized by irradiating the polymerizable composition layer with ultraviolet rays under the conditions of an illuminance of 150 mW / cm ² and a light intensity of 100 mJ / cm ² . The thickness of the polymerizable composition layer was adjusted so that the thickness of the obtained pressure-sensitive adhesive layer (X1) was the thickness shown in Table 1.
Next, a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., Cosmo Shine (registered trademark), product number "A4300", thickness: 50 μm) as a base material (Y) was applied to the exposed surface of the polymerizable composition layer. By sticking, a laminate in which the release film, the polymerizable composition layer, and the base material (Y) were laminated in this order was obtained. The storage elastic modulus E'(23) of the base material (Y) at 23 ° C. is 3.0 × 10 ⁹ Pa, and the storage elastic modulus of the heat-expandable particles of the base material (Y) at the expansion start temperature (t). E'(t) is 2.4 × 10 ⁹ Pa.
The laminated body obtained above, the release film side, illuminance 200 mW / cm ^2, light quantity ^{2,000mJ / cm 2 (500mJ / cm} 2 to 4 times irradiation) adhesive layer was irradiated with ultraviolet rays under the condition of ( X1) was formed, and a pressure-sensitive adhesive sheet in which the release film, the pressure-sensitive adhesive layer (X1) and the base material (Y) were laminated in this order was obtained.
The above-mentioned illuminance and amount of light during ultraviolet irradiation are values measured using an illuminance / light intensity meter (manufactured by EIT, product name "UV Power Pack II").

Comparative Examples 1 to 5
The release film, the non-expandable pressure-sensitive adhesive layer (X1') and the group are the same as in Example 1 except that the composition of the pressure-sensitive adhesive layer (X1) in Example 1 is changed to the composition shown in Table 1. An adhesive sheet in which the material (Y) was laminated in this order was obtained.

Comparative Example 6
A solvent-free polymerizable composition was prepared in the same manner as in Example 5 except that the urethane acrylate-based prepolymer was not blended in the pressure-sensitive adhesive main agent in Example 5.
Next, the solvent-free polymerizable composition was applied onto the peeled surface of a polyethylene terephthalate (PET) -based release film (manufactured by Lintec Corporation, product name "SP-PET38131", thickness: 38 μm). The viscosity was too low to form a coating film of the desired thickness.

Comparative Example 7
In Example 5, the same as in Example 5 except that 2-ethylhexyl acrylate and isobornyl acrylate were not blended in the pressure-sensitive main agent and the trifunctional monomer was not blended in the solvent-free polymerizable composition. To prepare a solvent-free polymerizable composition.
Next, the solvent-free polymerizable composition was applied onto the peeled surface of a polyethylene terephthalate (PET) -based release film (manufactured by Lintec Corporation, product name "SP-PET38131", thickness: 38 μm). The viscosity was too high to form a coating film.

Comparative Example 8
In Example 5, a pressure-sensitive adhesive sheet was produced in the same manner as in Example 5, except that the unmodified prepolymer prepared in Synthesis Example 1 was blended in place of the urethane acrylate-based prepolymer blended in the pressure-sensitive adhesive main agent.
The obtained adhesive sheet had a low cohesive force and did not self-peel in the evaluation of self-peeling property.

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

[Measurement of Adhesive Strength at 23 ° C. Before Thermal Expansion of Adhesive Layer (X1)]
The release film was removed from the adhesive layer (X1) of the adhesive sheet cut to 25 mm × 250 mm, and the surface of the exposed adhesive layer (X1) was 2 kg based on JIS Z0237: 2000 with respect to the mirror surface of the silicon mirror wafer. The film was bonded with a rubber roller of No. 1 and immediately after that, it was allowed to stand for 20 minutes in an environment of 23 ° C. and 50% RH (relative humidity).
After allowing to stand under the above conditions, in an environment of 23 ° C. and 50% RH (relative humidity), using a tensile tester (manufactured by A & D Co., Ltd., product name "Tensilon (registered trademark)"), Based on JIS Z0237: 2000, the adhesive strength was measured at a tensile speed of 300 mm / min by a 180 ° peeling method.

[Measurement of Adhesive Strength at 23 ° C after Thermal Expansion of Adhesive Layer (X1)]
Further, the above test sample is placed on the hot plate so that the silicon mirror wafer is on the side in contact with the hot plate and the adhesive sheet side is on the side not in contact with the hot plate, and the expansion start temperature of the heat-expandable particles is obtained. After heating at 100 ° C. for 1 minute and allowing to stand in a standard environment (23 ° C., 50% RH (relative humidity)) for 60 minutes, the tensile speed is increased by the 180 ° peeling method based on JIS Z0237: 2000. The adhesive strength of the pressure-sensitive adhesive layer (X1) was measured at 300 mm / min.
When the adhesive force was too small to be unintentionally peeled off when fixing the adhesive sheet for measurement, and it was difficult to measure the adhesive force, the adhesive force was assumed to be 0N / 25 mm.

[Evaluation of self-peeling property]
The release film was removed from the adhesive layer (X1) of the adhesive sheet cut to 50 mm × 50 mm, and the surface of the exposed adhesive layer (X1) was 2 kg based on JIS Z0237: 2000 with respect to the mirror surface of the silicon mirror wafer. As a test sample, the film was bonded with a rubber roller of No. 1 and left to stand for 20 minutes in an environment of 23 ° C. and 50% RH (relative humidity) immediately after that. Next, the test sample is placed on the hot plate so that the silicon mirror wafer is on the side in contact with the hot plate and the adhesive sheet side is on the side not in contact with the hot plate, and the temperature is equal to or higher than the expansion start temperature of the thermally expandable particles. It was heated at 100 ° C. for a maximum of 60 seconds. The ratio (%) of the peeled area of the pressure-sensitive adhesive sheet at the time of heating for 60 seconds (peeling area x 100 / the area of the entire pressure-sensitive adhesive sheet) was determined and evaluated based on the following criteria.
A: The adhesive sheet is completely peeled off within 60 seconds.
B: After heating for 60 seconds, the peeled area was 30% or more and less than 100%.
C: After heating for 60 seconds, the peeled area was less than 30%.
For the evaluation "A", the time (seconds) required for the entire surface to be peeled off was measured.

[Method for measuring adhesive strength and self-peeling property of non-expandable pressure-sensitive adhesive layer (X1') at 23 ° C.]
Regarding the adhesive strength and self-peeling property of the non-expandable pressure-sensitive adhesive layer (X1') prepared in Comparative Examples 1 to 5 at 23 ° C., the adhesive strength and self-peeling property of the above-mentioned pressure-sensitive adhesive layer (X1) at 23 ° C. The measurement was performed by a method in which the pressure-sensitive adhesive layer (X1) in the description of the measurement method was replaced with a non-expandable pressure-sensitive adhesive layer (X1').
However, "before thermal expansion" and "after thermal expansion" in "adhesive force of non-expandable pressure-sensitive adhesive layer (X1') at 23 ° C." in Table 2 are referred to as "in Comparative Examples 1 to 5". It shall mean "before heat treatment corresponding to thermal expansion treatment" and "after heat treatment corresponding to thermal expansion treatment of Examples", and "heat treatment corresponding to thermal expansion treatment of Examples" means [adhesive Measurement of adhesive strength at 23 ° C. after thermal expansion of the layer (X1)].

From Table 2, in each of the pressure-sensitive adhesive sheets of Examples 1 to 22, the pressure-sensitive adhesive layer can be satisfactorily formed even when the pressure-sensitive adhesive layer is formed by an energy ray-polymerizable component, which is sufficient before heat peeling. It can be seen that although it has adhesive strength, sufficient self-peeling property is obtained at the time of thermal peeling. Further, it can be seen that the adhesive strength and self-peeling property of these pressure-sensitive adhesive sheets can be adjusted by adjusting the composition of the polymerizable composition, the thickness of the pressure-sensitive adhesive layer (X1), and the like. On the other hand, none of the adhesive sheets of Comparative Examples 1 to 5 could be peeled off by heating.

1a, 1b, 2a,

2b Adhesive sheet

10, 10a, 10b Release material 3 Support 4 Laser light irradiation device 5 Modified area 6 Grinder 7 Thermocurable film 8 Support sheet W Semiconductor wafer W1 Circuit surface of semiconductor wafer and semiconductor chip Back side of W2 semiconductor wafer and semiconductor chip CP semiconductor chip

Claims

A pressure-sensitive adhesive sheet having a base material (Y) and a pressure-sensitive adhesive layer (X1) containing a polymer of an energy ray-polymerizable component and heat-expandable particles.
An energy ray is added to a polymerizable composition in which the polymer contains a monomer (a1) having an energy ray-polymerizable functional group and a prepolymer (a2) having an energy ray-polymerizable functional group as the energy ray-polymerizable component. An adhesive sheet that is a polymer formed by irradiation.
The pressure-sensitive adhesive sheet according to claim 1, wherein the component (a2) contains a prepolymer having two energy ray-polymerizable functional groups and having the energy ray-polymerizable functional groups at both ends.
The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the mass average molecular weight (Mw) of the component (a2) is 10,000 to 350,000.
The claim that the content ratio [(a2) / (a1)] of the component (a2) and the component (a1) in the polymerizable composition is 10/90 to 70/30 on a mass basis. The adhesive sheet according to any one of 1 to 3.
The pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the polymerizable composition contains a monomer having three or more energy ray-polymerizable functional groups as the component (a1).
The pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the polymerizable composition contains a monomer having an energy ray-polymerizable functional group and a hydroxy group as the component (a1).
The pressure-sensitive adhesive sheet according to any one of claims 1 to 6, wherein the polymerizable composition contains a monomer having an energy ray-polymerizable functional group and an alicyclic hydrocarbon group as the component (a1). ..
The pressure-sensitive adhesive sheet according to any one of claims 1 to 7, wherein the pressure-sensitive adhesive layer (X1) has a thickness of 5 to 150 μm at 23 ° C.
The adhesive sheet according to any one of claims 1 to 8, wherein the expansion start temperature (t) of the heat-expandable particles is 50 to 110 ° C.
A base material (Y), an adhesive layer (X1) provided on one surface side of the base material (Y), and an adhesive layer (X2) provided on the other surface side of the base material (Y). The adhesive sheet according to any one of claims 1 to 9, which comprises.
The method for producing an adhesive sheet according to any one of claims 1 to 10.
The method of forming the pressure-sensitive adhesive layer (X1) is to irradiate 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. A method for producing an adhesive sheet, which comprises a step of
The object to be processed is attached to the adhesive sheet according to any one of claims 1 to 10.
The object to be processed is subjected to one or more treatments selected from grinding treatment and individualization treatment.
A method for manufacturing a semiconductor device, which comprises a step of heating the pressure-sensitive adhesive sheet to a temperature equal to or higher than the expansion start temperature (t) to expand the pressure-sensitive adhesive layer (X1) after the treatment.
A method for manufacturing a semiconductor device including the following steps 1A to 5A.
Step 1A: A process of attaching the object to be processed to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet according to claim 10 and attaching a support to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet Step 2A: The processing. Step of applying one or more treatments selected from grinding treatment and individualization treatment to the object Step 3A: The surface of the processed object to which the treatment has been applied, opposite to the pressure-sensitive adhesive layer (X2). Step 4A: The pressure-sensitive adhesive sheet is heated to 120 ° C. or higher at the expansion start temperature (t) or higher, and the pressure-sensitive adhesive layer (X1) and the support are attached to the heat-curable film. Step 5A: Step of separating the pressure-sensitive adhesive layer (X2) from the object to be processed.
The pressure-sensitive adhesive layer (X2) is a pressure-sensitive adhesive layer that is hardened by irradiation with energy rays to reduce the adhesive strength.
The step 5A is a step of curing the pressure-sensitive adhesive layer (X2) by irradiating the pressure-sensitive adhesive layer (X2) with energy rays to separate the pressure-sensitive adhesive layer (X2) from the object to be processed. Item 13. The method for manufacturing a semiconductor device according to item 13.
A method for manufacturing a semiconductor device including the following steps 1B to 4B.
Step 1B: A process of attaching the object to be processed to the pressure-sensitive adhesive layer (X1) of the pressure-sensitive adhesive sheet according to claim 10 and attaching a support to the pressure-sensitive adhesive layer (X2) of the pressure-sensitive adhesive sheet Step 2B: The processing. Step of applying one or more treatments selected from grinding treatment and individualization treatment to the object Step 3B: The surface of the processed object to which the treatment has been applied, which is opposite to the adhesive layer (X1). Step 4B: The pressure-sensitive adhesive sheet is heated to 120 ° C. or higher at the expansion start temperature (t) or higher to heat the pressure-sensitive adhesive layer (X1) and the object to be processed. And the process of separating