JP6799186B1 - Curable Adhesive Composition, Adhesive Tape, Semiconductor Wafer Processing Method, and Semiconductor Device Manufacturing Method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable pressure-sensitive adhesive composition which is difficult to peel off during processing of an adherend and can be easily peeled off thereafter. SOLUTION: A curable pressure-sensitive adhesive composition containing a (meth) acrylic copolymer having a unit represented by the following general formula (1), a hydroxyl group-containing monomer unit, and a polymerization initiator. In the general formula (1), R1 represents a hydrocarbon group or the like, R2 represents a group containing two or more groups containing a radically polymerizable unsaturated bond, and R5 represents a hydrogen or methyl group. [Selection diagram] None

Description

The present invention relates to a curable pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer that is difficult to peel off even at high temperatures during the processing process of the adherend and can be easily peeled off after the process is completed. The present invention also relates to an adhesive tape having an adhesive layer containing the curable pressure-sensitive adhesive composition, a method for processing a semiconductor wafer using the adhesive tape, and a method for manufacturing a semiconductor device.

In the semiconductor chip manufacturing process, an adhesive tape is used to facilitate handling of wafers and semiconductor chips during processing and to prevent damage. For example, when a thick film wafer cut out from a high-purity silicon single crystal or the like is ground to a predetermined thickness to obtain a thin film wafer, grinding is performed after attaching an adhesive tape to the thick film wafer. Further, an adherend such as a wafer or a semiconductor chip is fixed to a support plate via an adhesive tape, and the adherend fixed to the support plate is treated.

Such an adhesive tape has high adhesiveness that can firmly fix an adherend such as a wafer or a semiconductor chip during a processing process, and does not damage the adherend such as a wafer or a semiconductor chip after the process is completed. It is required to be easily peeled off (also referred to as "high adhesive easy peeling").

As a re-peelable adhesive polymer or pressure-sensitive adhesive that realizes high adhesive and easy peeling, for example, in Patent Document 1, the side chain or main chain of the polymer is a polyfunctional monomer or oligomer having a radiopolymerizable functional group. Removable adhesive polymers that are bonded are described. A pressure-sensitive adhesive containing a removable adhesive polymer as described in Patent Document 1 can firmly fix an adherend during a processing process, and is cured by irradiating light such as ultraviolet rays to have adhesive strength. Can be easily peeled off after the process is completed.
Further, Patent Document 2 discloses a removable pressure-sensitive adhesive in which a non-silicone-based pressure-sensitive adhesive contains a silicone-based graft copolymer having a functional group capable of cross-linking with the base polymer of the pressure-sensitive adhesive. There is. Patent Document 2 describes that the removability is improved by using a silicone-based graft copolymer having an excellent effect of suppressing an increase in adhesive strength.

Japanese Unexamined Patent Publication No. 5-32946 Japanese Unexamined Patent Publication No. 2-123182

However, in recent years, there has been an increase in the number of treatments involving heating at a higher temperature than before, specifically, for example, 250 ° C. or higher, in a state where the adhesive tape is attached to an adherend such as a wafer or a semiconductor chip. At such a high temperature, the adhesive tape peels off in a short time after the start of the treatment, which causes a problem that the application temperature is limited.

An object of the present invention is to provide a curable pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer which is difficult to peel off even at a high temperature during a processing process of an adherend and can be easily peeled off after the process is completed. Another object of the present invention is to provide an adhesive tape having an adhesive layer containing the curable pressure-sensitive adhesive composition, a method for processing a semiconductor wafer using the adhesive tape, and a method for manufacturing a semiconductor device. To do.

The present invention is a curable pressure-sensitive adhesive composition containing a (meth) acrylic copolymer and a polymerization initiator, and the (meth) acrylic copolymer is represented by the following general formula (1). It is a curable pressure-sensitive adhesive composition having a structural unit and a structural unit derived from a hydroxyl group-containing monomer.

In the general formula (1), R ¹ represents a hydrocarbon group, an ether bond-containing group or an ester bond-containing group, R ² represents a group containing two or more groups containing a radically polymerizable unsaturated bond, and R ⁵ Represents a hydrogen or methyl group.
The present invention will be described in detail below.

The present inventors have used the (meth) acrylic copolymer as a (meth) acrylic copolymer in a curable pressure-sensitive adhesive composition containing a (meth) acrylic copolymer and cured by a stimulus such as heat or light in the presence of a polymerization initiator. It was examined to use a specific structural unit, particularly a copolymer having a structural unit having two or more groups containing a radically polymerizable unsaturated bond and a urethane bond. The pressure-sensitive adhesive layer formed by using such a curable pressure-sensitive adhesive composition has high flexibility when bonded to an adherend, and can be bonded with high adhesion. Furthermore, the present inventors cure the pressure-sensitive adhesive layer formed by using such a curable pressure-sensitive adhesive composition by a stimulus such as heat or light in the presence of a polymerization initiator, and the elastic modulus increases. It has been found that while the adhesive strength is reduced, the thermal decomposition is suppressed, so that the peeling at a high temperature is remarkably suppressed, and after the process is completed, the peeling can be easily performed and the adhesive residue is also remarkably suppressed. This has led to the completion of the present invention.

The curable pressure-sensitive adhesive composition of the present invention contains a (meth) acrylic copolymer and a polymerization initiator.
The (meth) acrylic copolymer has a structural unit represented by the following general formula (1).

In the general formula (1), R ¹ represents a hydrocarbon group, an ether bond-containing group or an ester bond-containing group, R ² represents a group containing two or more groups containing a radically polymerizable unsaturated bond, and R ⁵ Represents a hydrogen or methyl group.

The structural unit represented by the general formula (1) has a group containing two or more groups containing a radically polymerizable unsaturated bond represented by R ² and a urethane bond (-NH-COO-). It is a structural unit.
Since the (meth) acrylic copolymer has a structural unit represented by the general formula (1), the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition of the present invention can be applied to an adherend. At the time of bonding, it has high flexibility and can be bonded with high adhesion, but in the presence of a polymerization initiator, it is cured by a stimulus such as heat or light to increase the elastic modulus and decrease the adhesive strength. At this time, since two or more groups containing a radically polymerizable unsaturated bond are present, cross-linking during curing of the pressure-sensitive adhesive layer is compared with the case where only one group containing a radically polymerizable unsaturated bond is present. Since the density is greatly increased, the pressure-sensitive adhesive layer is less likely to be thermally decomposed even at a high temperature, and is less likely to be peeled off even at a high temperature. Further, since the urethane bond contained in the structural unit represented by the general formula (1) is relatively stable even at a high temperature, the presence of the urethane bond also makes it difficult for the adhesive layer to peel off even at a high temperature. ..
Further, the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition of the present invention is cured by a stimulus such as heat or light in the presence of a polymerization initiator to increase the elastic modulus and decrease the adhesive strength. Therefore, it can be easily peeled off after the process is completed, and the adhesive residue can be suppressed.

In the general formula (1), the hydrocarbon group represented by R ¹ and the ether bond-containing group or the ester bond-containing group are not particularly limited. For example, the hydrocarbon group is linear or branched. Examples thereof include chain hydrocarbon groups, alicyclic hydrocarbon groups, substituted or unsubstituted aromatic hydrocarbon groups and the like. Examples of the ether bond-containing group or ester bond-containing group include a group having an ether bond or an ester bond in the hydrocarbon group as described above. Of these, linear or branched chain hydrocarbon groups are preferable.
The linear or branched chain hydrocarbon group is not particularly limited, and an alkylene group having 1 to 20 carbon atoms is preferable. Specifically, for example, a methylene group, an ethylene group, an n-propylene group, or an isopropylene group. , N-butylene group, isobutylene group and the like.
In the above (meth) acrylic copolymer, R ¹ in the constituent units represented by a plurality of different general formulas (1) may be the same or different.

In the general formula (1), a group containing a group containing two or more radically polymerizable unsaturated bond represented by R ² is not particularly limited, examples of the group containing a radical-polymerizable unsaturated bond, For example, a vinyl group, a (meth) acryloyl group and the like can be mentioned. Of these, the (meth) acryloyl group is preferable. The groups containing two or more radically polymerizable unsaturated bonds in R ² may be the same or different. The R ² may have two or more groups containing the radically polymerizable unsaturated bond, and may have three or more groups containing the radically polymerizable unsaturated bond.
Specific examples of the group containing two or more groups containing a radically polymerizable unsaturated bond represented by R ² include 1,1- (bis (meth) acryloyloxymethyl) ethyl group and the like. ..
In the above (meth) acrylic copolymer, R ² in the constituent units represented by a plurality of different general formulas (1) may be the same or different.

In the general formula (1), said R ⁵ represents hydrogen or a methyl group.

More specifically, the structural unit represented by the general formula (1) is preferably the structural unit represented by the following general formula (1-A) because thermal decomposition can be further suppressed.

In the general formula (1-A), R ¹ represents a hydrocarbon group, an ether bond-containing group or an ester bond-containing group, and R ⁵ represents a hydrogen or methyl group.
^{R 1} and ^{R 5} in the formula (1-A) is the same as ^{R 1} and ^{R 5} in the general formula (1).

The method for introducing the structural unit represented by the general formula (1) into the (meth) acrylic copolymer is not particularly limited, and for example, as the acrylic monomer constituting the (meth) acrylic copolymer, the above Examples thereof include a method using an acrylic monomer as a constituent unit represented by the general formula (1).
Further, as the acrylic monomer, an acrylic monomer containing a hydroxyl group and a hydrocarbon group represented by R ¹ is used, and an isocyanate group that reacts with the hydroxyl group existing in the obtained polymer. And a method of reacting a compound having two or more groups containing a radically polymerizable unsaturated bond represented by R ² is also mentioned. By the reaction of such a hydroxyl group and an isocyanate group, a urethane bond as included in the structural unit represented by the general formula (1) is formed. Hereinafter, a compound having an isocyanate group and a group containing two or more groups containing a radically polymerizable unsaturated bond represented by R ² is also referred to as an "unsaturated bond-containing isocyanate compound".

Examples of the acrylic monomer containing the hydroxyl group and the hydrocarbon group represented by R ¹ include 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxyethyl ( Meta) acrylate and the like can be mentioned.
Examples of the unsaturated bond-containing isocyanate compound include 1,1- (bis (meth) acryloyloxymethyl) ethyl isocyanate.

The content of the structural unit represented by the general formula (1) in the (meth) acrylic copolymer is not particularly limited, but the preferable lower limit is 2 mol% and the preferable upper limit is 25 mol%. When the content of the structural unit is 2 mol% or more, the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition is more difficult to peel off even at a high temperature, and can be peeled off more easily after the process is completed. At the same time, the adhesive residue can be further suppressed. When the content of the structural unit is 25 mol% or less, it is possible to suppress adverse effects on the cohesive force, adhesive force and the like of the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition. The more preferable lower limit of the content of the structural unit is 4 mol%, the more preferable upper limit is 22 mol%, the further preferable lower limit is 6 mol%, and the further preferable upper limit is 20 mol%.
The content of the structural unit represented by the general formula (1) is determined by mass spectrometry of the (meth) acrylic copolymer and ¹ H-NMR measurement, and radical polymerization obtained by ¹ H-NMR measurement. It can be calculated from the integrated intensity of the peak of hydrogen derived from the sex unsaturated bond.

The (meth) acrylic copolymer has a structural unit derived from a hydroxyl group-containing monomer.
Since the (meth) acrylic copolymer has a structural unit derived from the hydroxyl group-containing monomer, the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition of the present invention has a high cohesive force and even at a high temperature. It becomes more difficult to peel off. Further, when the curable pressure-sensitive adhesive composition of the present invention contains a silicone compound and a cross-linking agent, the (meth) acrylic copolymer has a structural unit derived from the hydroxyl group-containing monomer, whereby the (meth) acrylic copolymer has the above (meth). ) The hydroxyl group of the acrylic copolymer can be sufficiently bonded to the silicone compound via the cross-linking agent. Therefore, it is possible to reduce the contamination of the adherend due to the bleed-out of the silicone compound.

The hydroxyl group-containing monomer is not particularly limited, and examples thereof include (meth) acrylic acid esters having a hydroxyl group.
More specifically, the structural unit derived from the hydroxyl group-containing monomer is preferably a structural unit represented by the following general formula (2) from the viewpoint of peeling resistance at high temperature and cohesive force.

In the general formula (2), R ⁴ represents a hydrocarbon group, an ether bond-containing group or an ester bond-containing group, and R ⁵ represents a hydrogen or methyl group.

In the general formula (2), the hydrocarbon group, ether bond-containing group or ester bond-containing group represented by R ⁴ is not particularly limited, and the hydrocarbon group, ether bond-containing group or ester bond-containing group represented by R ¹ is not particularly limited. Examples thereof include groups similar to the ester bond-containing group.
The structural unit represented by the general formula (2) may be a structural unit for introducing the structural unit represented by the general formula (1) into the (meth) acrylic copolymer. That is, by reacting the unsaturated bond-containing isocyanate compound with the hydroxyl group of the structural unit represented by the general formula (2), the (meth) acrylic copolymer is represented by the general formula (1). It is possible to introduce the structural unit to be used. Therefore, the hydrocarbon group, ether bond-containing group or ester bond-containing group represented by R ¹ is the same as the hydrocarbon group, ether bond-containing group or ester bond-containing group represented by R ^4. There may be.
However, if all the hydroxyl groups of the structural unit represented by the general formula (2) react with the unsaturated bond-containing isocyanate compound, the (meth) acrylic copolymer becomes the general formula (2). ) Can no longer have a structural unit. Therefore, it is necessary to adjust the reactivity by appropriately adjusting the type, reaction conditions, reaction ratio, etc. of the unsaturated bond-containing isocyanate compound.

The method for introducing the structural unit represented by the general formula (2) into the (meth) acrylic copolymer is not particularly limited, and examples thereof include the following methods. That is, the acrylic monomer constituting the (meth) acrylic copolymer, a structural unit represented by the above general formula (2), a hydroxyl group, a hydrocarbon group represented by R ^4, an ether bond-containing Examples thereof include a method using an acrylic monomer containing a group or an ester bond-containing group.
And the hydroxyl group, the hydrocarbon group represented by R ^4, the acrylic monomer containing an ether bond-containing group or an ester bond-containing group is, for example, 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl ( Examples thereof include meta) acrylate and 2-hydroxyethyl (meth) acrylate.

The content of the structural unit derived from the hydroxyl group-containing monomer is not particularly limited, but the preferable lower limit is 0.1 mol% and the preferable upper limit is 20 mol%. When the content of the structural unit is 0.1 mol% or more, the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition has a sufficiently high cohesive force and is more difficult to peel off even at a high temperature. When the content of the structural unit is 0.1 mol% or more, the curable pressure-sensitive adhesive composition of the present invention contains a silicone compound and a cross-linking agent, the (meth) acrylic copolymer is used. Since it can be more sufficiently bonded to the silicone compound via the cross-linking agent, contamination of the adherend can be reduced. When the content of the structural unit is 20 mol% or less, it is possible to prevent the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition from becoming too hard. The more preferable lower limit of the content of the structural unit is 2 mol%, and the more preferable upper limit is 17 mol%.
The content of the structural unit derived from the hydroxyl group-containing monomer can be calculated from the mass spectrometry of the (meth) acrylic copolymer and ¹ H-NMR measurement.

The (meth) acrylic copolymer further preferably has a structural unit derived from a carboxyl group-containing monomer.
Since the (meth) acrylic copolymer has a structural unit derived from the carboxyl group-containing monomer, the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition has a high cohesive force and is more peeled off even at a high temperature. It becomes difficult to do. Further, when the curable pressure-sensitive adhesive composition of the present invention contains a silicone compound and a cross-linking agent, the (meth) acrylic copolymer has a structural unit derived from the carboxyl group-containing monomer. The carboxyl group of the meta) acrylic copolymer can be sufficiently bonded to the silicone compound via a cross-linking agent. Therefore, it is possible to reduce the contamination of the adherend due to the bleed-out of the silicone compound.

Examples of the carboxyl group-containing monomer include (meth) acrylic acid.
More specifically, the structural unit derived from the carboxyl group-containing monomer is preferably a structural unit represented by the following general formula (3).

In the general formula (3), R ⁵ represents a hydrogen or methyl group.

The method for introducing the structural unit represented by the general formula (3) into the (meth) acrylic copolymer is not particularly limited, and for example, as the acrylic monomer constituting the (meth) acrylic copolymer, the above An example is a method using (meth) acrylic acid, which is a structural unit represented by the general formula (3).

The content of the structural unit derived from the carboxyl group-containing monomer in the (meth) acrylic copolymer is not particularly limited, but the preferable lower limit is 0.1 mol% and the preferable upper limit is 5 mol%. When the content of the structural unit is 0.1 mol% or more, the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition has a sufficiently high cohesive force and is more difficult to peel off even at a high temperature. When the content of the structural unit is 0.1 mol% or more, the curable pressure-sensitive adhesive composition of the present invention contains a silicone compound and a cross-linking agent, the (meth) acrylic copolymer is used. Since it can be more sufficiently bonded to the silicone compound via the cross-linking agent, contamination of the adherend can be reduced. When the content is 5 mol% or less, it is possible to prevent the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition from becoming too hard. The more preferable lower limit of the content of the structural unit is 1 mol%, and the more preferable upper limit is 3 mol%.
The content of the structural unit derived from the carboxyl group-containing monomer can be calculated from the mass spectrometry of the (meth) acrylic copolymer and the ¹ H-NMR measurement.

In addition to the structural unit represented by the general formula (1), the structural unit derived from the hydroxyl group-containing monomer, and the structural unit derived from the carboxyl group-containing monomer, the (meth) acrylic copolymer contains other radicals. It may have a structural unit derived from a polymerizable monomer.

The other radically polymerizable monomers are not particularly limited, and examples thereof include (meth) acrylic acid esters, monomers having polar functional groups such as amide groups and nitrile groups, and vinyl compounds. Among them, (meth) acrylic acid ester is preferable from the viewpoint of cohesive force, adhesive force and the like.
More specifically, the structural unit derived from the other radically polymerizable monomer is preferably a structural unit represented by the following general formula (4).

In the general formula (4), R ³ represents a hydrocarbon group, an ether bond-containing group or an ester bond-containing group, and R ⁵ represents a hydrogen or methyl group.

In the general formula (4), the hydrocarbon group represented by R ^3, an ether bond-containing group or an ester bond-containing group is not particularly limited, for example, as the hydrocarbon group, linear or branched Examples thereof include chain hydrocarbon groups, alicyclic hydrocarbon groups, substituted or unsubstituted aromatic hydrocarbon groups and the like. Examples of the ether bond-containing group or ester bond-containing group include a group having an ether bond or an ester bond in the hydrocarbon group as described above.
The linear or branched chain hydrocarbon group is not particularly limited, and an alkyl group having 1 to 20 carbon atoms is preferable, and specifically, for example, a methyl group, an ethyl group, a propyl group, an n-butyl group, and the like. Examples thereof include a tert-butyl group, a 2-ethylhexyl group, an n-octyl group, an isooctyl group, an isomyristyl group and a stearyl group.
The alicyclic hydrocarbon group is not particularly limited, and examples thereof include a cyclohexyl group and an isobornyl group.
The substituted or unsubstituted aromatic hydrocarbon group is not particularly limited, and examples thereof include a benzyl group and the like.
The ether bond-containing group is not particularly limited, and examples thereof include a 2-butoxyethyl group, a 2-phenoxyethyl group, a glycidyl group, a tetrahydrofurfuryl group, and a polypropylene glycol group.
In the above (meth) acrylic copolymer, R ³ in the constituent units represented by a plurality of different general formulas (4) may be the same or different.

In the general formula (4), said R ⁵ represents hydrogen or a methyl group.

The method for introducing the structural unit represented by the general formula (4) into the (meth) acrylic copolymer is not particularly limited, and examples thereof include the following methods. That is, the acrylic monomer constituting the (meth) acrylic copolymer, a structural unit represented by the above general formula (4), the hydrocarbon group represented by R ^3, an ether bond-containing group or an ester Examples thereof include a method using an acrylic monomer containing a bond-containing group.

The content of the structural unit represented by the general formula (4) in the (meth) acrylic copolymer is not particularly limited, but the structural unit represented by the general formula (4) is the same as the (meth) acrylic. It is preferably a structural unit that is the main component of the polymer. The preferable lower limit of the content of the structural unit represented by the general formula (4) is 50 mol%, and the preferable upper limit is 95 mol%. When the content of the structural unit is within the above range, the cohesive force, the adhesive force, and the like of the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition are sufficiently exhibited. The more preferable lower limit of the content of the structural unit is 60 mol%, and the more preferable upper limit is 90 mol%.
The content of the structural unit represented by the general formula (4) can be calculated from the mass spectrometry of the (meth) acrylic copolymer and the ¹ H-NMR measurement.

Among the other radically polymerizable monomers, examples of the monomer having an amide group include hydroxyethyl acrylamide, isopropyl acrylamide, dimethyl aminopropyl acrylamide and the like. Examples of the monomer having a nitrile group include acrylonitrile.

The weight average molecular weight of the (meth) acrylic copolymer is not particularly limited, but the preferable lower limit is 300,000 and the preferable upper limit is 2 million. When the weight average molecular weight is within the above range, the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition has high flexibility and can be bonded with high adhesion when bonded to an adherend. Therefore, it becomes more difficult to peel off even at high temperatures. The more preferable lower limit of the weight average molecular weight is 400,000, and the more preferable upper limit is 1.6 million.

The molecular weight distribution (Mw / Mn) of the (meth) acrylic copolymer is not particularly limited, but the preferable lower limit is 1.5 and the preferable upper limit is 7.0. When the molecular weight distribution (Mw / Mn) is within the above range, the cohesive force, adhesive force, and the like of the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition are sufficiently exhibited. The more preferable lower limit of the molecular weight distribution (Mw / Mn) is 2.0, and the more preferable upper limit is 6.0.

In order to adjust the weight average molecular weight and the molecular weight distribution (Mw / Mn) within the above ranges, for example, the composition, polymerization method, polymerization conditions, etc. of the (meth) acrylic copolymer may be adjusted.
The weight average molecular weight and the molecular weight distribution (Mw / Mn) can be measured by the following methods.
The solution of the (meth) acrylic copolymer is filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The obtained filtrate was supplied to a gel permeation chromatograph (for example, 2690 Separations Model manufactured by Waters), GPC measurement was performed under the conditions of a sample flow rate of 1 mL / min and a column temperature of 40 ° C., and the polystyrene-equivalent molecular weight of the copolymer was measured. Is measured to obtain the weight average molecular weight and the molecular weight distribution (Mw / Mn). For example, GPC KF-806L (manufactured by Showa Denko KK) is used as the column, and a differential refractometer is used as the detector.

The (meth) acrylic copolymer is obtained by copolymerizing a monomer mixture. In order to copolymerize the monomer mixture to obtain the (meth) acrylic copolymer, the monomer mixture may be radically polymerized in the presence of a polymerization initiator. A conventionally known method is used as a method for radically polymerizing the above-mentioned monomer mixture, that is, a polymerization method, and examples thereof include solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, and bulk polymerization. Examples of the reaction method for radical polymerization of the monomer mixture include living radical polymerization and free radical polymerization.

The (meth) acrylic copolymer is preferably a (meth) acrylic copolymer obtained by living radical polymerization. According to the living radical polymerization, a copolymer having a more uniform molecular weight and composition as compared with the free radical polymerization can be obtained, and the production of low molecular weight components can be suppressed. Therefore, the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition has a high cohesive force and is more difficult to peel off even at a high temperature.

In the above-mentioned living radical polymerization, various polymerization methods may be adopted. For example, the ATRP method using an iron, ruthenium or copper catalyst and a halogen-based initiator may be used, the NMP method using TEMPO or the like may be used, or an organic tellurium polymerization initiator may be used.

A dispersion stabilizer may be used when radically polymerizing the monomer mixture. Examples of the dispersion stabilizer include polyvinylpyrrolidone, polyvinyl alcohol, methyl cellulose, ethyl cellulose, poly (meth) acrylic acid, poly (meth) acrylic acid ester, polyethylene glycol and the like.
When a polymerization solvent is used for radical polymerization of the monomer mixture, the polymerization solvent is not particularly limited. Examples of the polymerization solvent include non-protic solvents such as hexane, cyclohexane, octane, toluene and xylene, water, methanol, ethanol, propanol, butanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dioxane, N, N-dimethyl. Highly polar solvents such as formamide can be used. These polymerization solvents may be used alone or in combination of two or more.
The polymerization temperature is preferably 0 to 110 ° C. from the viewpoint of the polymerization rate.

The curable pressure-sensitive adhesive composition of the present invention contains a polymerization initiator.
The above-mentioned polymerization initiator is not particularly limited, and examples thereof include a photopolymerization initiator and a thermal polymerization initiator. Among them, a step of separately curing the pressure-sensitive adhesive layer because the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition of the present invention can be cured by the heat when the adherend is subjected to a treatment involving heating. A thermal polymerization initiator is preferable because it does not require the above and can be cured even when it is used for an adherend that does not transmit light.

The photopolymerization initiator is not particularly limited, and examples thereof include those that are activated by irradiating light having a wavelength of 250 to 800 nm. Examples of such photopolymerization initiators include acetophenone derivative compounds, benzoin ether compounds, ketal derivative compounds, phosphine oxide derivative compounds, bis (η5-cyclopentadienyl) titanosen derivative compounds, benzophenone, Michler ketone, chlorothioxanthone, and the like. Examples thereof include dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, α-hydroxycyclohexylphenylketone, 2-hydroxymethylphenylpropane and the like.
Examples of the acetophenone derivative compound include methoxyacetophenone and the like. Examples of the benzoin ether-based compound include benzoin propyl ether and benzoin isobutyl ether. Examples of the ketal derivative compound include benzyldimethyl ketal, acetophenone diethyl ketal and the like.
These photopolymerization initiators may be used alone or in combination of two or more.

The above-mentioned thermal polymerization initiator is not particularly limited, and examples thereof include those that are decomposed by heat to generate active radicals that initiate a polymerization reaction. Specifically, for example, dicumyl peroxide, di-t-butyl peroxide, t-butylperoxybenzoale, t-butylhydroperoxide, benzoyl peroxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, para. Mentan hydroperoxide, di-t-butyl peroxide and the like can be mentioned. These thermal polymerization initiators may be used alone or in combination of two or more.

The content of the polymerization initiator is not particularly limited and is appropriately determined depending on the type of the (meth) acrylic copolymer and the polymerization initiator, but is preferable with respect to 100 parts by weight of the (meth) acrylic copolymer. The lower limit is 0.1 parts by weight, the preferred upper limit is 10 parts by weight, the more preferable lower limit is 1 part by weight, and the more preferable upper limit is 8 parts by weight.

The curable pressure-sensitive adhesive composition of the present invention preferably further contains a silicone compound.
By containing the silicone compound, in the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition, the silicone compound moves molecules and gathers on the surface of the pressure-sensitive adhesive layer, and the surface of the pressure-sensitive adhesive layer is hydrophobic. It becomes. As a result, the pressure-sensitive adhesive layer and the adherend are less likely to interact with each other, so that the adhesion of the pressure-sensitive adhesive layer can be reduced even at high temperatures, and the pressure-sensitive adhesive layer can be more easily peeled off and glue is used after the process is completed. The rest can be suppressed more.

The silicone compound preferably has a crosslinkable functional group.
When the silicone compound has the crosslinkable functional group, the silicone compound can be bonded to the (meth) acrylic copolymer via a crosslinking agent. As a result, contamination of the adherend due to bleeding out of the silicone compound can be reduced.
The crosslinkable functional group is not particularly limited as long as it is a functional group capable of crosslinking with the (meth) acrylic copolymer, and is appropriately determined according to the functional group present in the (meth) acrylic copolymer. For example, a carboxyl group, a hydroxyl group, a glycidyl group, an amide group, a nitrile group and the like can be mentioned. Of these, carboxyl groups and hydroxyl groups are preferable, and carboxyl groups are more preferable.

The silicone compound is not particularly limited as long as it is a compound having a siloxane bond, and specific examples thereof include silicone oil, modified silicone oil, silicone-based graft copolymer, and silicone-based block copolymer. Of these, a silicone-based graft copolymer is preferable because it easily collects on the surface of the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition and can further reduce the adhesion enhancement of the pressure-sensitive adhesive layer even at a high temperature.
The modified silicone oil is not particularly limited, and examples thereof include epoxy-modified silicone oil and carbinol-modified silicone oil.

The silicone-based graft copolymer is a copolymer having a graft chain containing a siloxane bond in the side chain.
The silicone-based graft copolymer is not particularly limited, but preferably has a structural unit derived from a silicone macromonomer.
The silicone macromonomer is not particularly limited as long as it is a monomer having a siloxane bond-containing group, and examples thereof include acrylic silicone macromonomers and styrene silicone macromonomers. Among them, an acrylic silicone macromonomer is preferable because it is excellent in heat resistance and weather resistance, and an acrylic silicone macromonomer having a structure represented by the following general formula (5) or (6) is more preferable.

Here, R represents a (meth) acryloyl group-containing functional group, and X and Y each independently represent an integer of 0 or 1 or more.
Examples of R include (meth) acryloyl groups. The upper limit of X and Y is not particularly limited, but X and Y are usually 5000 or less, preferably 500 or less, and more preferably 200 or less.

The weight average molecular weight of the silicone macromonomer is not particularly limited, but the preferred lower limit is 500 and the preferred upper limit is 50,000. When the weight average molecular weight is within the above range, the hydrophobic surface layer formed by the silicone-based graft copolymer becomes thick, so that the adhesion enhancement of the pressure-sensitive adhesive layer can be reduced even at a high temperature, and the step After the completion, the pressure-sensitive adhesive layer can be peeled off more easily and the adhesive residue can be further suppressed. The more preferable lower limit of the weight average molecular weight is 1000, and the more preferable upper limit is 20,000.

The content of the structural unit derived from the silicone macromonomer is not particularly limited, but the preferable lower limit in the silicone-based graft copolymer is 1% by weight, and the preferable upper limit is 90% by weight. When the content is within the above range, the adhesion of the pressure-sensitive adhesive layer can be reduced even at a high temperature, the pressure-sensitive adhesive layer can be more easily peeled off after the process is completed, and the adhesive residue can be further suppressed. A more preferable lower limit of the content is 5% by weight, a more preferable upper limit is 80% by weight, a further preferable lower limit is 10% by weight, and a further preferable upper limit is 60% by weight.

When the silicone-based graft copolymer has the crosslinkable functional group, the crosslinkable functional group may be present in the graft chain of the silicone-based graft copolymer or in the main chain. It may be present in the graft chain and the main chain.

In order to have the crosslinkable functional group, the silicone-based graft copolymer preferably has a structural unit derived from the monomer having the crosslinkable functional group.
The monomer having the crosslinkable functional group is not particularly limited, and when the crosslinkable functional group is a carboxyl group, examples of the monomer having a carboxyl group include (meth) acrylic acid and the like. When the crosslinkable functional group is a hydroxyl group, examples of the monomer having a hydroxyl group include hydroxyl groups such as 4-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 2-hydroxyethyl (meth) acrylate. Examples thereof include (meth) acrylic acid esters having. When the crosslinkable functional group is a glycidyl group, examples of the monomer having a glycidyl group include glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether. When the crosslinkable functional group is an amide group, examples of the monomer having an amide group include hydroxyethyl acrylamide, isopropyl acrylamide, dimethyl aminopropyl acrylamide and the like. When the crosslinkable functional group is a nitrile group, examples of the monomer having a nitrile group include acrylonitrile. These monomers may be used alone or in combination of two or more.

The content of the structural unit derived from the monomer having a crosslinkable functional group is not particularly limited, but the preferable lower limit in the silicone-based graft copolymer is 1% by weight, and the preferable upper limit is 20% by weight. When the content is within the above range, the silicone-based graft copolymer is sufficiently bonded to the (meth) acrylic copolymer, and the (meth) acrylic copolymers have a sufficient crosslinked structure. Since it can be constructed, the pressure-sensitive adhesive layer is more difficult to peel off even at a high temperature, and after the process is completed, the pressure-sensitive adhesive layer can be peeled off more easily and the adhesive residue can be further suppressed. The more preferable lower limit of the content is 3% by weight, and the more preferable upper limit is 15% by weight.

Further, the crosslinkable functional group may be a radically polymerizable unsaturated bond. In this case, in order for the silicone-based graft copolymer to have the radically polymerizable unsaturated bond, a functional group that reacts with the functional group existing in the silicone-based graft copolymer is used. It is preferable to react a compound having a radically polymerizable unsaturated bond.
Such a compound is not particularly limited, and can be appropriately selected depending on the functional group present in the silicone-based graft copolymer. When the functional group present in the silicone-based graft copolymer is a carboxyl group, a compound having an epoxy group and a radically polymerizable unsaturated bond, a compound having an isocyanate group and a radically polymerizable unsaturated bond, or the like may be used. Used. When the functional group present in the silicone-based graft copolymer is a hydroxyl group, a compound having an isocyanate group and a radically polymerizable unsaturated bond is used. When the functional group present in the silicone-based graft copolymer is an epoxy group, a compound having a carboxyl group and a radically polymerizable unsaturated bond, a compound having an amide group and a radically polymerizable unsaturated bond, or the like may be used. Used. When the functional group present in the silicone-based graft copolymer is an amino group, a compound having an epoxy group and a radically polymerizable unsaturated bond is used.

In addition to the structural unit derived from the silicone macromonomer and the structural unit derived from the monomer having a crosslinkable functional group, the silicone-based graft copolymer further comprises a (meth) acrylic acid ester, a vinyl compound, and other components. It may have a structural unit derived from a monomer having a polar functional group or the like.

The (meth) acrylic acid ester is not particularly limited, and examples thereof include (meth) acrylic acid alkyl ester.
Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, tert-butyl (meth) acrylate, and 2-ethylhexyl ( Examples thereof include meta) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isomyristyl (meth) acrylate, and stearyl (meth) acrylate.
Examples of the (meth) acrylic acid ester include cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, 2-butoxyethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, and glycidyl (meth). Examples thereof include meta) acrylate, tetrahydrofurfuryl (meth) acrylate, and polypropylene glycol mono (meth) acrylate.
These (meth) acrylic acid esters may be used alone or in combination of two or more. Of these, 2-ethylhexyl acrylate is preferable because it can impart an appropriate adhesive strength.

The vinyl compound is not particularly limited, and examples thereof include styrene and vinyl acetate. These vinyl compounds may be used alone or in combination of two or more.

The weight average molecular weight of the silicone-based graft copolymer is not particularly limited, but the preferable upper limit is 400,000. When the weight average molecular weight is 400,000 or less, the silicone-based graft copolymer easily moves in the pressure-sensitive adhesive layer and easily collects on the surface of the pressure-sensitive adhesive layer. Therefore, the adhesion of the pressure-sensitive adhesive layer is enhanced even at a high temperature. It can be reduced, and after the process is completed, the adhesive layer can be more easily peeled off and the adhesive residue can be further suppressed. The more preferable upper limit of the weight average molecular weight is 300,000, the more preferable upper limit is 250,000, and the particularly preferable upper limit is 200,000, which is usually 10,000 or more.

The method for producing the silicone-based graft copolymer is not particularly limited, and it can be obtained by copolymerizing a monomer mixture. The method for obtaining a silicone-based graft copolymer by copolymerizing the above-mentioned monomer mixture is not particularly limited, and the same method as in the case of the above-mentioned (meth) acrylic copolymer can be used.

The content of the silicone compound is not particularly limited, but the preferable lower limit with respect to 100 parts by weight of the (meth) acrylic copolymer is 1 part by weight, and the preferable upper limit is 20 parts by weight. When the content is 1 part by weight or more, the adhesion of the pressure-sensitive adhesive layer can be reduced even at a high temperature, the pressure-sensitive adhesive layer can be more easily peeled off after the process is completed, and the adhesive residue can be further suppressed. When the content is 20 parts by weight or less, the initial adhesive strength of the pressure-sensitive adhesive layer is high, and the white turbidity of the pressure-sensitive adhesive layer can be suppressed. A more preferable lower limit of the content is 2 parts by weight, a more preferable upper limit is 15 parts by weight, a further preferable lower limit is 3 parts by weight, and a further preferable upper limit is 10 parts by weight.
When the silicone compound is the silicone-based graft copolymer, the silicone-based graft copolymer tends to collect on the surface of the pressure-sensitive adhesive layer, and therefore, it should be used in a relatively small amount among the silicone compounds. Can be done. Regarding the content of the silicone-based graft copolymer, the preferable lower limit is 0.1 parts by weight, the preferable upper limit is 10 parts by weight, and the more preferable lower limit is 0.5 parts by weight with respect to 100 parts by weight of the (meth) acrylic copolymer. The more preferable upper limit is 5 parts by weight, and the more preferable lower limit is 1 part by weight.

The curable pressure-sensitive adhesive composition of the present invention preferably further contains a cross-linking agent.
Since the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition of the present invention contains the above-mentioned cross-linking agent, it is easy to adjust the cohesive force of the pressure-sensitive adhesive layer by cross-linking the above-mentioned (meth) acrylic copolymer. Become. As a result, the initial adhesive strength of the pressure-sensitive adhesive layer is increased, the pressure-sensitive adhesive layer is more difficult to peel off even at a high temperature, and the pressure-sensitive adhesive layer can be peeled off more easily after the process is completed, and adhesive residue can be further suppressed. ..
The above-mentioned cross-linking agent is not particularly limited, and examples thereof include isocyanate-based cross-linking agents, epoxy-based cross-linking agents, aziridine-based cross-linking agents, and metal chelate-based cross-linking agents. Of these, an isocyanate-based cross-linking agent is preferable because the cohesive force of the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition is increased.

The cross-linking agent preferably has a functional group capable of cross-linking with the (meth) acrylic copolymer and the silicone compound.
When the cross-linking agent has a functional group capable of cross-linking with the (meth) acrylic copolymer and the silicone compound, the silicone compound can be bonded to the (meth) acrylic copolymer via the cross-linking agent. it can. As a result, contamination of the adherend due to bleeding out of the silicone compound can be reduced.
Such a crosslinkable functional group is not particularly limited, and is appropriately determined according to the functional groups present in the (meth) acrylic copolymer and the silicone compound.

The content of the cross-linking agent is not particularly limited, but from the viewpoint of obtaining a more appropriate cohesive force and from the viewpoint of sufficiently binding the (meth) acrylic copolymer and the silicone compound, the (meth) acrylic copolymer The preferable lower limit with respect to 100 parts by weight is 0.01 parts by weight, and the preferable upper limit is 1 part by weight. The more preferable lower limit of the content of the cross-linking agent is 0.1 parts by weight, and the more preferable upper limit is 0.5 parts by weight.

The curable pressure-sensitive adhesive composition of the present invention may further contain a gas generating agent.
By containing the above gas generating agent, a gas is released at the interface between the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition and the adherend by a stimulus such as heat or light, and the released gas Since at least a part of the pressure-sensitive adhesive layer is peeled off by the pressure, the pressure-sensitive adhesive layer can be peeled off more easily after the process is completed.

The gas generator is not particularly limited, but a gas generator that generates a gas by light irradiation is preferable. Among them, when the curable pressure-sensitive adhesive composition of the present invention is photocurable, a gas generator having an absorption wavelength different from the absorption wavelength of the photopolymerization initiator is more preferable, and light having a wavelength of 300 nm or less is irradiated. Therefore, a gas generator that generates gas is more preferable. For example, when a photopolymerization initiator having an absorption wavelength near 365 nm or 405 nm and a gas generator that absorbs a wavelength near 254 nm are contained, a gas is unintentionally exposed to light when the curable pressure-sensitive adhesive composition is cured. It is possible to prevent gas from being generated from the generator and causing peeling.

From the viewpoint of heat resistance, the gas generator preferably contains a carboxylic acid compound, a tetrazole compound, or a salt thereof, and more preferably contains a tetrazole compound or a salt thereof.
More specifically, the gas generating agent contains a carboxylic acid compound represented by the following general formula (7), a tetrazole compound represented by the following general formulas (10) to (12), or a salt thereof. Is preferable. While these gas generators generate gas (carbon dioxide or nitrogen gas) by irradiating with light such as ultraviolet rays, they have high heat resistance that does not decompose even at a high temperature of about 200 ° C.

In the general formula (7), R ^{1 to} R ⁷ represent hydrogen or an organic group, respectively. R ^{1 to} R ⁷ may be the same or different. Two of R ^{1 to} R ⁷ may be bonded to each other to form a cyclic structure.

In the general formulas (10) to (12), R ²¹ and R ²² represent hydrogen, an alkyl group having 1 to 7 carbon atoms, an alkylene group, a phenyl group, a mercapto group, a hydroxyl group or an amino group, respectively.

The organic group represented by R ^{1 to} R ⁷ in the above general formula (7) is, for example, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group or an isobutyl group, or an alkoxy group such as a methoxy group or an ethoxy group. The group etc. can be mentioned. Further, a carboxyl group, a hydroxyl group, a nitro group and the like can be mentioned. Further, examples thereof include aromatic groups such as phenyl groups, polycyclic hydrocarbon groups such as naphthyl groups, fluorenyl groups and pyrenyl groups, ring-assembled hydrocarbon groups such as biphenyl groups, and heterocyclic groups such as xanthenyl groups. Among them, one of R ^{3 to} R ^{7 in} the above general formula (7) is an organic group represented by the following general formula (8), or R ³ in the above general formula (7). It is preferable that two adjacent two of ~ R ⁷ are bonded to each other to form an annular structure represented by the following general formula (9).

In the general formula (8), R ^{8 to} R ¹² represent hydrogen or an organic group, respectively. R ^{8 to} R ¹² may be the same or different. Two of R ^{8 to} R ¹² may be bonded to each other to form a cyclic structure.
In the general formula (9), R ^{13 to} R ¹⁶ represent hydrogen or an organic group, respectively. R ^{13 to} R ¹⁶ may be the same or different. Two of R ^{13 to} R ¹⁶ may be bonded to each other to form a cyclic structure.
Further, R ¹ in the general formula (7) is preferably a methyl group.

Specific examples of the carboxylic acid compound represented by the general formula (7) include phenylacetic acid, diphenylacetic acid, triphenylacetic acid, 2-phenylpropionic acid, 2,2-diphenylpropionic acid, 2,2,2. -Triphenylpropionic acid, 2-phenylbutylic acid, α-methoxyphenylacetic acid, mandelic acid, atrolactonic acid, benzicic acid, tropic acid, phenylmalonic acid, phenylsuccinic acid, 3-methyl-2-phenylbutyric acid, orthotoluyl Acetic acid, metatoluyl acetic acid, 4-isobutyl-α-methylphenyl acetic acid, paratoluyl acetic acid, 1,2-phenylenedic acetic acid, 1,3-phenylenedic acid, 1,4-phenylenedic acetic acid, 2-methoxyphenyl acetic acid, 2- Hydroxyphenyl acetic acid, 2-nitrophenyl acetic acid, 3-nitrophenyl acetic acid, 4-nitrophenyl acetic acid, 2- (4-nitrophenyl) propionic acid, 3- (4-nitrophenyl) propionic acid, 4- (4-nitro) Phenyl) propionic acid, 3,4-dimethoxyphenyl acetic acid, 3,4- (methylenedioxy) phenyl acetic acid, 2,5-dimethoxyphenyl acetic acid, 3,5-dimethoxyphenyl acetic acid, 3,4,5-trimethoxyphenyl Acetic acid, 2,4-dinitrophenyl acetic acid, 4-biphenyl acetic acid, 1-naphthyl acetic acid, 2-naphthyl acetic acid, 6-methoxy-α-methyl-2-naphthyl acetic acid, 1-pyrene acetic acid, 9-fluorene carboxylic acid or 9H -Xantene-9-carboxylic acid and the like can be mentioned.

Among them, the carboxylic acid compound represented by the general formula (7) is preferably ketoprofen or 2-xanthone acetic acid.

The salt of the carboxylic acid compound represented by the general formula (7) goes through a complicated synthetic route only by mixing the carboxylic acid compound represented by the general formula (7) and the basic compound in a container. It can be easily prepared without any need.
The basic compound is not particularly limited, and examples thereof include amines, hydrazine compounds, quaternary ammonium hydroxide salts, and phosphine compounds. The amine is not particularly limited, and any of a primary amine, a secondary amine and a tertiary amine can be used. Among them, monoalkylamine or dialkylamine is preferable as the basic compound. When a monoalkylamine or a dialkylamine is used, the polarity of the obtained salt of the carboxylic acid compound represented by the general formula (7) can be lowered, and the salt can be dissolved with the (meth) acrylic copolymer or the like. Can enhance sex. The basic compound is more preferably a monoalkylamine or a dialkylamine having 6 to 12 carbon atoms.

Since the salts of the tetrazole compounds represented by the general formulas (10) to (12) also have a skeleton derived from the tetrazole compounds represented by the general formulas (10) to (12), they are irradiated with light. And nitrogen gas can be generated.
The salt of the tetrazole compound represented by the general formulas (10) to (12) is not particularly limited, and examples thereof include sodium salt, potassium salt, and ammonium salt.

The salt of the tetrazole compound represented by the general formulas (10) to (12) can be prepared by simply mixing the tetrazole compound represented by the general formulas (10) to (12) and the basic compound in a container. It can be easily prepared without going through a complicated synthetic pathway.
The basic compound is not particularly limited, and examples thereof include amines, hydrazine compounds, quaternary ammonium hydroxide salts, and phosphine compounds. The amine is not particularly limited, and any of a primary amine, a secondary amine and a tertiary amine can be used. Among them, monoalkylamine or dialkylamine is preferable as the basic compound. When a monoalkylamine or a dialkylamine is used, the polarity of the obtained salt of the tetrazole compound represented by the general formulas (10) to (12) can be lowered, and the above (meth) acrylic copolymer or the like can be used. Solubility with can be increased. The basic compound is more preferably a monoalkylamine or a dialkylamine having 6 to 12 carbon atoms.

The tetrazole compound represented by the general formula (10) or a salt thereof is not particularly limited, but specifically, for example, 1H-tetrazole, 5-phenyl-1H-tetrazole, 5,5-azobis-1H-tetrazole, 5 -Amino-1H-tetrazole, 5-methyl-1H-tetrazole, 1-methyl-5-mercapto-1H-tetrazole, 1-methyl-5-ethyl-1H-tetrazole, 1- (dimethylaminoethyl) -5-mercapto -1H-tetrazole and the like can be mentioned.

The tetrazole compound represented by the general formula (11) or a salt thereof is not particularly limited, and specific examples thereof include a 5,5'-bistetrazole diammonate salt and a 5,5'-bistetrazole sodium salt. Be done.

The tetrazole compound represented by the general formula (12) or a salt thereof is not particularly limited, and specific examples thereof include 5,5'-bistetrazoleamine monoammonium salt and the like.

Regarding the content of the gas generating agent, the preferable lower limit is 5 parts by weight and the preferable upper limit is 50 parts by weight with respect to 100 parts by weight of the (meth) acrylic copolymer. When the content of the gas generating agent is 5 parts by weight or more, the gas is sufficiently generated by light irradiation or the like, and the pressure-sensitive adhesive layer can be more easily peeled off after the process is completed. When the content of the gas generator is 50 parts by weight or less, the solubility of the gas generator and the (meth) acrylic copolymer or the like can be enhanced. The more preferable lower limit of the content of the gas generating agent is 10 parts by weight, and the more preferable upper limit is 35 parts by weight.

Further, the curable pressure-sensitive adhesive composition of the present invention includes inorganic fillers such as fumed silica, photosensitizers, plasticizers, resins, surfactants, waxes, fine particle fillers, antioxidants, ultraviolet absorbers and the like. It may contain a known additive.

In the curable pressure-sensitive adhesive composition of the present invention, the preferable upper limit of the weight loss rate after heating at 280 ° C. for 1 hour is 15% by weight. When the weight loss rate after heating is 15% by weight or less, the amount of outgas generated from the (meth) acrylic copolymer is reduced, and the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition has a high temperature. But it becomes more difficult to peel off. The more preferable upper limit of the weight loss rate after heating is 12% by weight, and the more preferable upper limit is 10% by weight. The lower limit of the weight loss rate after heating is not particularly limited, and the closer it is to 0% by weight, the more difficult it is for the adhesive layer to peel off even at high temperatures, which is preferable.
The method for adjusting the weight loss rate after heating within the above range is not particularly limited, and the type, composition, physical properties, content, etc. of the (meth) acrylic copolymer, the silicone compound, and the like may be adjusted.
The weight loss rate after heating can be measured by the following method.
After obtaining a measurement sample consisting only of the curable pressure-sensitive adhesive composition or the pressure-sensitive adhesive layer, the weight is measured. In a nitrogen atmosphere (nitrogen flow, flow rate 50 mL / min), a measurement sample is measured at a heating rate of 10 ° C./min using a differential thermogravimetric simultaneous measuring device (for example, TG-DTA; STA7200 manufactured by Hitachi High-Tech Science Co., Ltd.). Heat from 25 ° C to 280 ° C, reach 280 ° C, maintain 280 ° C and heat for 1 hour. After allowing to cool, the weight loss is measured, and the weight loss rate is calculated from the obtained weight loss and the weight before heating.

The tin component content of the curable pressure-sensitive adhesive composition of the present invention is not particularly limited, but the preferable upper limit in terms of tin is 0.05% by weight. The tin component contained in the curable pressure-sensitive adhesive composition of the present invention is mainly a catalyst used in producing the (meth) acrylic copolymer and / or the side of the (meth) acrylic copolymer. It is derived from the catalyst used when introducing a radically polymerizable unsaturated bond into the chain. If the tin component content is 0.05% by weight or less, the tin component acts as a catalyst at high temperature and the above ( Since the alkyl ester portion of the meta) acrylic copolymer can be suppressed from being decomposed to outgas, the pressure-sensitive adhesive layer formed by using the curable pressure-sensitive adhesive composition becomes more difficult to peel off even at a high temperature. A more preferable upper limit of the tin component content is 0.03% by weight. The lower limit of the tin component content is not particularly limited, and the closer to 0% by weight, the more difficult the pressure-sensitive adhesive layer is to peel off even at a high temperature, which is preferable.
The method for adjusting the tin component content within the above range is not particularly limited, and a method for adjusting the addition amount of the catalyst used in producing the (meth) acrylic copolymer, the above (meth) acrylic copolymer. Examples include a method of purifying the acrylic by reprecipitation or the like.
The tin component content can be measured by an ICP emission spectrophotometer (5110 ICP-OES or an equivalent product manufactured by Agilent).

An adhesive tape having an adhesive layer containing the curable pressure-sensitive adhesive composition of the present invention is also one of the present inventions.
The adhesive tape of the present invention may have another layer as long as it has the above-mentioned adhesive layer. Further, the adhesive tape of the present invention may be a support type having a base material or a non-support type having no base material. When the pressure-sensitive adhesive tape of the present invention has a base material, the pressure-sensitive adhesive layer may be provided on at least one surface of the base material, and it may be a single-sided pressure-sensitive adhesive tape or a double-sided pressure-sensitive adhesive tape. When the adhesive tape of the present invention is a double-sided adhesive tape having a base material, the pressure-sensitive adhesive layer is also provided on the other surface of the base material as long as the pressure-sensitive adhesive layer is provided on at least one surface of the base material. It may have the same pressure-sensitive adhesive layer as above, or it may have a pressure-sensitive adhesive layer having a composition and physical properties different from that of the pressure-sensitive adhesive layer on the other surface of the base material.

The pressure-sensitive adhesive layer preferably has a storage elastic modulus G'before curing at 23 ° C. of 5.0 × 10 ³ Pa or more and 2.0 × 10 ⁸ Pa or less. When the storage elastic modulus is in the above range, the pressure-sensitive adhesive layer can suppress adhesive residue while exhibiting appropriate adhesive strength, and is sufficient even when used for an adherend having large irregularities. Can follow. The more preferable lower limit of the storage elastic modulus is 0.1 × 10 ⁵ Pa, the more preferable lower limit is 0.2 × 10 ⁵ Pa, the more preferable upper limit is 200 × 10 ⁵ Pa, and the further preferable upper limit is 20 × 10 ⁵ Pa. ..

The pressure-sensitive adhesive layer preferably has a storage elastic modulus G'after curing at 23 ° C. of 2.0 × 10 ⁵ Pa or more and 2.0 × 10 ⁸ Pa or less. When the storage elastic modulus is in the above range, the pressure-sensitive adhesive layer can suppress adhesive residue while exhibiting appropriate adhesive strength, and is sufficient even when used for an adherend having large irregularities. Can follow. The more preferable lower limit of the storage elastic modulus is 1.0 × 10 ⁶ Pa, the more preferable upper limit is 1.0 × 10 ⁸ Pa, and the more preferable upper limit is 5.0 × 10 ⁷ Pa.
When the pressure-sensitive adhesive layer is thermosetting, the state after heating at 120 ° C. for 1 hour and then at 175 ° C. for 1 hour is defined as after curing, and when the pressure-sensitive adhesive layer is photocurable, The state after irradiating the pressure-sensitive adhesive layer with ultraviolet rays of 405 nm using an ultra-high pressure mercury ultraviolet irradiation device so that the integrated intensity becomes 2500 mJ / cm ² is defined as after curing. The storage elastic modulus of the pressure-sensitive adhesive layer before and after curing at 23 ° C. was determined by a method in accordance with JIS K 7244, using a dynamic viscoelasticity measuring device (for example, DVA-200, manufactured by IT Measurement Control Co., Ltd.). It can be measured under the conditions of tensile compression mode and angular frequency of 1 Hz.

The thickness of the pressure-sensitive adhesive layer is not particularly limited, but the preferable lower limit is 5 μm and the preferable upper limit is 200 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, the pressure-sensitive adhesive tape can be attached to the adherend with sufficient adhesive strength, and adhesive residue can be suppressed after the process is completed. The more preferable lower limit of the thickness of the pressure-sensitive adhesive layer is 10 μm, and the more preferable upper limit is 150 μm.

When the adhesive tape of the present invention is a non-support type, its layer structure is not particularly limited and may be composed of a single layer composed of the pressure-sensitive adhesive layer, or may be composed of a plurality of layers including the pressure-sensitive adhesive layer. May be good.
The non-support type adhesive tape composed of a plurality of layers including the pressure-sensitive adhesive layer includes, for example, a structure in which the pressure-sensitive adhesive layer and another pressure-sensitive adhesive layer are laminated, and the pressure-sensitive adhesive containing no gas generating agent. Examples thereof include a configuration in which the agent layer and the pressure-sensitive adhesive layer containing a gas generating agent are laminated.

When the adhesive tape of the present invention is a support type, its layer structure is not particularly limited, and it may be a single-sided adhesive tape composed of a base material and the pressure-sensitive adhesive layer, and the base material and the base material may be used. It may be a double-sided adhesive tape having the above-mentioned pressure-sensitive adhesive layer laminated on at least one surface.
As a structure of the support type double-sided adhesive tape having the base material and the pressure-sensitive adhesive layer laminated on at least one surface of the base material, for example, the pressure-sensitive adhesive layer is provided on one surface of the base material. Examples thereof include a configuration having another pressure-sensitive adhesive layer on the other surface, a configuration having the above-mentioned pressure-sensitive adhesive layer on both surfaces of the base material, and the like. Above all, from the viewpoint of heat resistance and easy peeling after the process is completed, a structure having the above-mentioned pressure-sensitive adhesive layer on both surfaces of the base material is preferable. That is, the adhesive tape of the present invention preferably has a base material and the pressure-sensitive adhesive layer laminated on both surfaces of the base material.

The configuration of the pressure-sensitive adhesive tape having the base material and the pressure-sensitive adhesive layer laminated on both surfaces of the base material is not particularly limited and can be selected depending on the semiconductor processing process used. Among them, it is preferable that at least one of the pressure-sensitive adhesive layers contains a gas generating agent, and more specifically, for example, the pressure-sensitive adhesive layer containing a gas generating agent on one surface of a base material. On the other surface, a photocurable pressure-sensitive adhesive layer that does not contain a gas generating agent is laminated. Further, a configuration in which the pressure-sensitive adhesive layer containing a gas generating agent is laminated on one surface of the base material and the thermosetting pressure-sensitive adhesive layer containing no gas generating agent is laminated on the other surface can be mentioned.
Further, as a structure of the pressure-sensitive adhesive tape having the base material and the pressure-sensitive adhesive layer laminated on both surfaces of the base material, at least one of the pressure-sensitive adhesive layers is thermosetting. The structure is also preferable, and more specifically, for example, a structure in which the thermosetting adhesive layer containing no gas generating agent is laminated on both surfaces of the base material can be mentioned.

When the adhesive tape of the present invention is a support type, the material constituting the base material is not particularly limited, but a material having heat resistance is preferable. Examples of materials having heat resistance include polyethylene terephthalate, polyethylene naphthalate, polyacetal, polyamide, polycarbonate, polyphenylene ether, polybutylene terephthalate, ultrahigh molecular weight polyethylene, syndiotactic polystyrene, polyarylate, polysulfone, polyethersulfon, and the like. Examples thereof include polyphenylene stereide, polyetheretherketone, polyimide, polyetherimide, fluororesin, and liquid crystal polymer. Of these, polyimide is preferable because it has excellent heat resistance.

The thickness of the base material is not particularly limited, but a preferable lower limit is 15 μm and a preferable upper limit is 250 μm. When the thickness of the base material is within the above range, an adhesive tape having excellent handleability can be obtained. A more preferable lower limit of the thickness of the base material is 25 μm, and a more preferable upper limit is 125 μm.

The ultraviolet transmittance of the base material is not particularly limited. When the pressure-sensitive adhesive layer is UV-curable, the UV transmittance of the base material is preferably 50% or more. When the ultraviolet transmittance of the base material is within the above range, the ultraviolet curing of the pressure-sensitive adhesive layer becomes easy. The ultraviolet transmittance of the base material is more preferably 60% or more, and further preferably 75% or more. The upper limit of the ultraviolet transmittance is not particularly limited, and the higher the upper limit, the better, usually 100% or less.

The ultraviolet transmittance of the adhesive tape of the present invention is not particularly limited. When the pressure-sensitive adhesive layer is UV-curable, in particular, the pressure-sensitive adhesive tape of the present invention has a base material and the pressure-sensitive adhesive layer laminated on both surfaces of the base material, and the pressure-sensitive adhesive layer is eventually used. In the case of UV curability, the adhesive tape of the present invention preferably has an ultraviolet transmittance of 30% or more. When the ultraviolet transmittance of the adhesive tape of the present invention is within the above range, the adhesive layer can be easily cured by ultraviolet rays and peeled by ultraviolet irradiation. The ultraviolet transmittance of the adhesive tape of the present invention is more preferably 40% or more, and further preferably 55% or more. The upper limit of the ultraviolet transmittance is not particularly limited, and the higher the upper limit, the better, usually 100% or less.
The ultraviolet transmittance of the base material and the adhesive tape can be measured using a spectrophotometer (U-3900, manufactured by Hitachi, Ltd., or an equivalent product thereof).

The method for producing the adhesive tape of the present invention is not particularly limited, and examples thereof include the following methods.
First, a silicone-based graft copolymer, a cross-linking agent, a polymerization initiator and, if necessary, other additives are added to the solution of the (meth) acrylic copolymer and mixed to obtain a pressure-sensitive adhesive solution. Next, the pressure-sensitive adhesive solution is applied onto the release film and dried to form a pressure-sensitive adhesive layer. The obtained pressure-sensitive adhesive layer is bonded to a base material to produce an pressure-sensitive adhesive tape.

The use of the adhesive tape of the present invention is not particularly limited, but it is preferably used in the semiconductor processing process in the manufacture of semiconductor devices such as semiconductor chips and display devices (OLEDs, liquid crystal display devices, etc.) or electronic components. More specifically, in the manufacture of semiconductor devices or electronic components, an adherend such as a wafer or a semiconductor chip is temporarily fixed on an adhesive tape, or an adherend such as a wafer or a semiconductor chip is supported via the adhesive tape. It is preferably used when the adherend temporarily fixed is treated after being temporarily fixed on the plate.
Since the adhesive tape of the present invention is difficult to peel off even at a high temperature during the processing process of the adherend and can be easily peeled off after the process is completed, the adhesive tape is conventionally attached to the adherend such as a wafer or a semiconductor chip. It can also be suitably used when performing a treatment involving heating at the above high temperature, specifically, for example, 250 ° C. or higher.

A method for processing a semiconductor wafer using the adhesive tape of the present invention, which comprises a temporary fixing step of temporarily fixing the semiconductor wafer on the adhesive tape of the present invention and a treatment involving heating of 250 ° C. or higher on the surface of the semiconductor wafer. A method for processing a semiconductor wafer, which comprises a semiconductor wafer processing step to be applied and an adhesive tape peeling step for peeling the adhesive tape of the present invention from the semiconductor wafer, is also one of the present inventions.

In the above-mentioned treatment involving heating at 250 ° C. or higher, the upper limit of the heating temperature is not particularly limited, and substantially 400 ° C. is the upper limit, and the preferable upper limit is 300 ° C.
The treatment involving heating at 250 ° C. or higher is not particularly limited, and for example, a reflow step, a sputtering step, a vapor deposition step, an etching step, a chemical vapor deposition (CVD) step, a physical vapor deposition (PVD) step, and a resist coating step. , Patterning step, molding step and other heat treatments or treatments involving heat generation.
The method for peeling the adhesive tape of the present invention from the semiconductor wafer is not particularly limited, and examples thereof include peel peeling and laser peeling.
Instead of the adhesive tape peeling step of peeling the adhesive tape of the present invention from the semiconductor wafer, a semiconductor wafer peeling step of peeling the semiconductor wafer from the adhesive tape of the present invention such as peeling by a needle pickup may be used.

When the adhesive tape of the present invention is a double-sided adhesive tape, more specifically, for example, the following method can be mentioned as a method for manufacturing a semiconductor device in which the adhesive tape of the present invention can be preferably used. That is, a temporary fixing step of temporarily fixing the semiconductor wafer on the support via the adhesive tape of the present invention, a semiconductor wafer processing step of applying a treatment of the surface of the semiconductor wafer with heating of 250 ° C. or higher, and the support. Alternatively, a method for manufacturing a semiconductor device having an adhesive tape peeling step of peeling the adhesive tape of the present invention from the semiconductor wafer or both thereof can be mentioned. A method for manufacturing such a semiconductor device is also one of the present inventions.

In the temporary fixing step, the method of temporarily fixing the semiconductor wafer on the support via the adhesive tape of the present invention is not particularly limited, but one of the adhesive layers in the adhesive tape of the present invention and the semiconductor wafer such as a silicon wafer , And then the other pressure-sensitive adhesive layer and a support such as glass are bonded together.
In the temporary fixing step, when the adhesive tape of the present invention has an adhesive layer containing a gas generating agent, it is preferable to bond the adhesive layer containing the gas generating agent and the support.

In the method for producing a semiconductor device of the present invention, a pressure-sensitive adhesive layer curing step for curing the pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape of the present invention may be performed before or after the temporary fixing step. The pressure-sensitive adhesive layer curing step may be performed before or after the temporary fixing step.
Further, from the viewpoint of suppressing the adhesion of the pressure-sensitive adhesive layer, it is preferable that the pressure-sensitive adhesive layer curing step is performed before the semiconductor wafer processing step. Specifically, for example, one pressure-sensitive adhesive layer in the pressure-sensitive adhesive tape of the present invention is bonded to a semiconductor wafer such as a silicon wafer, and then the other pressure-sensitive adhesive layer and a support such as glass are bonded to each other. It is preferable to perform the pressure-sensitive adhesive layer curing step and then the semiconductor wafer processing step.

In the method for manufacturing a semiconductor device of the present invention, the semiconductor wafer processing step may be performed after performing another step after the temporary fixing step.
Examples of the other steps include a step of thinning a semiconductor wafer by back grinding, a wafer level molding step, and the like.

The adhesive tape peeling step is not particularly limited, and the adhesive tape of the present invention can be peeled by a conventionally known method. That is, a needle pickup method in which the semiconductor wafer is pushed up with a needle, a needleless pickup method in which a needle is not used, or the like may be used.

When the adhesive tape of the present invention has an adhesive layer containing a gas generating agent, the adhesive tape of the present invention can be more easily generated by stimulating the adhesive tape in the above-mentioned adhesive tape peeling step to generate gas from the gas generating agent. Can be peeled off.
For example, when a gas generator that generates a gas by irradiating light having a wavelength of 300 nm or less is used as the gas generator, the gas is released from the gas generator by irradiating light having a wavelength of 300 nm or less. It can be generated to more easily peel off the adhesive tape of the present invention. For such a gas generating agent, for example, it is preferable to irradiate light having a wavelength of 254 nm with an illuminance of 5 mW / cm ² or more, more preferably with an illuminance of 10 mW / cm ² or more, and 20 mW / cm. Irradiation with an illuminance of ² or more is more preferable, and irradiation with an illuminance of 50 mW / cm ² or more is particularly preferable. Further, it is preferable to irradiate light having a wavelength 254nm at 1000 mJ / cm ² or more accumulated illuminance, 1000 mJ / cm ² or more, more preferably irradiated with 20 J / cm ² or less of accumulated illuminance. It is more preferable to irradiate light having a wavelength of 254 nm with an integrated illuminance of 1500 mJ / cm ² or more and 15 J / cm ² or less, and particularly preferably to irradiate with an integrated illuminance of 2000 mJ / cm ² or more and 10 J / cm ² or less.

In the adhesive tape peeling step, a laser peeling step of peeling the adhesive tape of the present invention by laser irradiation may be performed. By laser irradiation, the adhesive tape of the present invention can be more easily peeled off even when an adhesive tape or the like in which the thermosetting adhesive layer containing no gas generating agent is laminated is used.
When the adhesive tape of the present invention is peeled by the laser peeling step, the pressure-sensitive adhesive layer peeled by the laser peeling step of the adhesive tape of the present invention preferably has an absorption peak in the wavelength range of 250 to 400 nm. Since the absorption peak is within the above range, peeling by laser irradiation can be performed more reliably. The absorption peak can be adjusted by adding, for example, an ultraviolet absorber or the like.
The absorption peak of the pressure-sensitive adhesive layer can be measured using a spectrophotometer (U-3900, manufactured by Hitachi, Ltd., or an equivalent product thereof).

The support is not particularly limited, and examples thereof include glass, a polyimide film, and a glass epoxy substrate.

According to the present invention, it is possible to provide a curable pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer that is difficult to peel off even at a high temperature during the processing process of an adherend and can be easily peeled off after the process is completed. Further, according to the present invention, it is possible to provide an adhesive tape having an adhesive layer containing the curable pressure-sensitive adhesive composition, a method for processing a semiconductor wafer using the adhesive tape, and a method for manufacturing a semiconductor device. it can.

Hereinafter, embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Synthesis Example 1)
(Polymerization of (meth) acrylic copolymer)
A reactor equipped with a thermometer, a stirrer, and a cooling tube was prepared, and a total of 100 parts by weight of the monomer mixture shown in Table 1, 60 parts by weight of ethyl acetate, and 60 parts by weight of toluene were added to the reactor. The reactor was heated to 60 ° C. Subsequently, 0.15 parts by weight of V-60 (2,2'-azobisisobutyronitrile) was charged into the reactor as a polymerization initiator, and the polymerization reaction was carried out at 60 ° C. for 8 hours to contain the polymer. A solution was obtained.
To 100 parts by weight of the obtained polymer, 0.2 part by weight of dioctyltin dilaurate and 10 ppm of hydroquinone were added to the reaction vessel and heated to 60 ° C. Subsequently, 8 parts by weight of 1,1- (bisacryloyloxymethyl) ethyl isocyanate (BEI, bifunctional) is added dropwise to the reaction vessel over 1 hour, and the reaction is further carried out at 60 ° C. for 6 hours. To obtain a (meth) acrylic copolymer-containing solution.

¹ H-NMR measurement was carried out on the obtained (meth) acrylic copolymer. From the integrated intensity of the hydrogen peak derived from the obtained radically polymerizable unsaturated bond, the content of the structural unit derived from 1,1- (bisacryloyloxymethyl) ethyl isocyanate (BEI, bifunctional) was determined and shown in the table. Shown in 1. In addition, the content of the structural units derived from each acrylic monomer was calculated from mass spectrometry and ¹ H-NMR measurement, and is shown in Table 1.

The obtained (meth) acrylic copolymer-containing solution was diluted 50-fold with tetrahydrofuran (THF). The obtained diluted solution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm). The obtained filtrate was supplied to a gel permeation chromatograph (2690 Separations Model manufactured by Waters), GPC measurement was performed under the conditions of a sample flow rate of 1 mL / min and a column temperature of 40 ° C., and polystyrene of a (meth) acrylic copolymer was obtained. The converted molecular weight was measured. As a result, the weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) were determined. A GPC KF-806L (manufactured by Showa Denko KK) was used as the column, and a differential refractometer was used as the detector.

(Synthesis Examples 2 to 13)
(Polymerization of (meth) acrylic copolymer)
The composition of the monomer mixture was changed as shown in Table 1, and other unsaturated bond-containing compounds were used instead of the unsaturated bond-containing isocyanate compound as shown in Table 1 in the same manner as in Synthesis Example 1. A meta) acrylic copolymer was obtained.
The (meth) acrylic copolymers obtained in Synthesis Examples 10 and 11 have a structural unit having only one group containing a radically polymerizable unsaturated bond and a urethane bond. is there. The (meth) acrylic copolymer obtained in Synthesis Example 12 has a structural unit having two or more groups containing a radically polymerizable unsaturated bond and a urethane bond, but the structural unit is It is different from the structural unit represented by the general formula (1). The (meth) acrylic copolymer obtained in Synthesis Example 13 does not have a radically polymerizable unsaturated bond.

Details of the materials listed in Table 1 are shown below.
(A) Acrylic monomer 2EHA (2- (ethylhexyl) acrylate)
AAc (acrylic acid)
4HBA (4-hydroxybutyl acrylate)
AOI-BP (blocked isocyanate, 2-[(3,5-dimethylpyrazolyl) carbonylamino] ethyl acrylate)

(B) Unsaturated bond-containing isocyanate compound BEI (bifunctional, 1,1- (bisacryloyloxymethyl) ethyl isocyanate)

(C) Other unsaturated bond-containing compound MOI (monofunctional, 2-methacryloyloxyethyl isocyanate)
AOI (monofunctional, 2-acryloyloxyethyl isocyanate)
PETA (trifunctional, pentaerythritol triacrylate)

(Synthesis Example A)
(Synthesis of silicone-based graft copolymer)
A reactor equipped with a thermometer, a stirrer, and a cooling tube was prepared, and a total of 100 parts by weight of the monomer mixture shown in Table 2 and 80 parts by weight of ethyl acetate were added into the reactor. The reactor was heated to initiate reflux. Subsequently, 0.1 part by weight of 2,2'-azobisisobutyronitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., V-60) was added as a polymerization initiator into the above reactor, and polymerization was carried out under reflux. Was started. Next, 0.1 parts by weight of 2,2'-azobisisobutyronitrile (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., V-60) was added 2 hours after the start of the polymerization to continue the polymerization reaction. It was. Then, 7 hours after the start of the polymerization, an ethyl acetate solution of the silicone-based graft copolymer was obtained.
The weight average molecular weight (Mw) and the molecular weight distribution (Mw / Mn) were determined in the same manner as in Synthesis Example 1.

(Synthesis Examples B to C)
(Synthesis of silicone-based graft copolymer)
A silicone-based graft copolymer was obtained in the same manner as in Synthesis Example A except that the composition of the monomer mixture was changed as shown in Table 2.

(Synthesis Example D)
(Synthesis of silicone-based graft copolymer)
A polymer-containing solution was obtained in the same manner as in Synthesis Example A except that the composition of the monomer mixture (excluding 2-methacryloyloxyethyl isocyanate (MOI)) was changed as shown in Table 2.
To 100 parts by weight of the obtained polymer, 10 ppm of hydroquinone was added to the reaction vessel and heated to 60 ° C. Subsequently, 5 parts by weight of 2-methacryloyloxyethyl isocyanate (MOI) was added dropwise to the reaction vessel over 60 minutes, and the reaction was further carried out at 60 ° C. for 120 minutes to contain a silicone-based graft copolymer. A solution was obtained.

Details of the materials listed in Table 2 are shown below.
2EHA (2- (ethylhexyl) acrylate)
Silicone macromonomer (one-ended methacryloyl-modified polydimethylsiloxane, manufactured by Shin-Etsu Chemical Co., Ltd., weight average molecular weight 4600)
AAc (acrylic acid)
4HBA (4-hydroxybutyl acrylate)
MOI (2-methacryloyloxyethyl isocyanate)

(Example 1)
To 100 parts by weight of the non-volatile content of the (meth) acrylic copolymer-containing solution, ethyl acetate was added and stirred, and as shown in Table 3, a silicone compound, a polymerization initiator and a cross-linking agent were added and stirred. A solution containing a curable pressure-sensitive adhesive composition having a non-volatile content of 30% by weight was obtained. The obtained solution is coated on a 25 μm-thick polyimide (PI) film having a corona treatment on one side with a doctor knife so that the thickness of the dry film is 40 μm, and heated at 110 ° C. for 5 minutes. The coating solution was dried. Then, it was statically cured at 40 ° C. for 3 days to obtain an adhesive tape.

After obtaining a measurement sample consisting of only the pressure-sensitive adhesive layer, the weight was measured. In a nitrogen atmosphere (nitrogen flow, flow rate 50 mL / min), a differential thermogravimetric simultaneous measuring device (TG-DTA; STA7200, manufactured by Hitachi High-Tech Science Co., Ltd.) was used to measure a sample at a temperature rise rate of 10 ° C./min at 25 ° C. After reaching 280 ° C., the temperature was maintained at 280 ° C. and heated for 1 hour. After allowing to cool, the amount of weight loss was measured, and the weight loss rate was calculated from the obtained amount of weight loss and the weight before heating.

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape was supplied to an ICP emission spectrophotometer (5110 ICP-OES manufactured by Agilent) for measurement, and the tin component content of the pressure-sensitive adhesive layer was measured.

(Examples 2 to 15, 17 to 20 and Reference Example 16 )
An adhesive tape was obtained in the same manner as in Example 1 except that the composition of the pressure-sensitive adhesive layer was changed as shown in Table 3.

(Examples 21 and 22)
An adhesive tape was obtained in the same manner as in Example 1 except that the composition of the pressure-sensitive adhesive layer and the type of the base material were changed as shown in Table 4.
As the gas generator, 20 parts by weight of bistetrazole Na salt (manufactured by Masuda Chemical Co., Ltd.) was used with respect to 100 parts by weight of the non-volatile content of the (meth) acrylic copolymer-containing solution. As a base material, a polyethylene naphthalate (PEN) film having a thickness of 25 μm with one side treated with corona was used, and the ultraviolet transmittance was measured using a spectrophotometer (U-3900, manufactured by Hitachi, Ltd.).

(Examples 23 to 25)
An adhesive tape was obtained in the same manner as in Example 1 except that the composition of the pressure-sensitive adhesive layer and the type of the base material were changed as shown in Table 5 and the pressure-sensitive adhesive layers were formed on both sides of the base material.
The method for producing the adhesive tape was as follows. That is, first, the thickness of the dry film of the curable pressure-sensitive adhesive composition-containing solution constituting the pressure-sensitive adhesive layer 1 is 15 μm on the release-treated surface of the polyethylene terephthalate film whose surface has been released-treated. The coating was applied with a doctor knife and heated at 110 ° C. for 5 minutes to dry the coating solution to obtain an adhesive layer 1. On the other hand, the thickness of the dry film of the curable pressure-sensitive adhesive composition-containing solution constituting the pressure-sensitive adhesive layer 2 is 80 μm on the release-treated surface of another polyethylene terephthalate film whose surface has been released-treated. The coating was applied with a doctor knife and heated at 110 ° C. for 5 minutes to dry the coating solution to obtain an adhesive layer 2. As a base material, a 25 μm polyethylene naphthalate (PEN) film having corona treatment on both sides or a 25 μm thick polyimide (PI) film having corona treatment on both sides was prepared, and the adhesive layer 1 was applied to both sides of the base material. The pressure-sensitive adhesive layers 2 were bonded to each other to obtain an pressure-sensitive adhesive tape.
As the gas generator, 20 parts by weight of bistetrazole Na salt (manufactured by Masuda Chemical Co., Ltd.) was used with respect to 100 parts by weight of the non-volatile content of the (meth) acrylic copolymer-containing solution. The ultraviolet transmittance of the base material and the absorption peak of the adhesive layer 2 were measured using a spectrophotometer (U-3900, manufactured by Hitachi, Ltd.).

(Comparative Examples 1 to 4)
An adhesive tape was obtained in the same manner as in Example 1 except that the composition of the pressure-sensitive adhesive layer was changed as shown in Table 6.

<Evaluation>
The adhesive tapes obtained in Examples , Reference Examples and Comparative Examples were evaluated by the following methods. The results are shown in Tables 3 and 4.

(1) High temperature (280 ° C) peeling evaluation (1-1) High temperature (280 ° C) peeling evaluation of single-sided adhesive tape Adhesive obtained in Examples 1 to 15 , 17 to 22 , Reference Example 16 and Comparative Examples 1 to 4. The following evaluations were made on the tape.
The adhesive tape was cut to a width of 25 mm. Glass (Large slide glass white edge polishing No. 2 manufactured by Matsunami Glass Industry Co., Ltd.) using a 2 kg pressure-bonded rubber roller to cut the adhesive tape in an environment with a room temperature of 23 ° C and a relative humidity of 50% at a speed of 10 mm / sec. I pasted it on. In Examples 1 to 15 , 18 to 21, Reference Example 16 and Comparative Examples 1 to 4, in which the pressure-sensitive adhesive layer was a thermosetting type, heat treatment was performed at 150 ° C. for 10 minutes to cure the pressure-sensitive adhesive layer. In Examples 17 and 22, in which the pressure-sensitive adhesive layer was a photocurable type, the pressure-sensitive adhesive layer was cured by irradiating an ultra-high pressure mercury lamp at an intensity of 20 mW / cm ² for 150 seconds and then heat-treating at 150 ° C. for 10 minutes. .. Then, heat treatment at 280 ° C. for 60 minutes was performed once.
The time until the adhesive tape floated during the heat treatment was measured and used as the peeling time. The case where the peeling time was within 5 minutes was shown as x, the case where the peeling time exceeded 5 minutes and was within 60 minutes was shown as ◯, and the case where the peeling time exceeded 60 minutes was shown as ⊚.
The glass after the adhesive tape was peeled off was visually observed to evaluate the residue. The case where the residue was found on the glass was shown as x, the case where the residue was found only on the edge of the glass was shown as ◯, and the case where no residue was found was shown as ⊚.

(1-2) Evaluation of High Temperature (280 ° C.) Peeling of Double-sided Adhesive Tape For the adhesive tapes obtained in Examples 23 to 25, a laminate having a glass support, an adhesive tape, and a semiconductor wafer in this order was used as follows. Evaluation was performed.
In an environment of room temperature of 23 ° C. and relative humidity of 50%, the surface of the adhesive layer 2 of the adhesive tape was attached to an 8-inch silicon mirror wafer at a speed of 10 mm / sec using a 2 kg pressure-bonding rubber roller. Next, the surface of the pressure-sensitive adhesive layer 1 was attached to glass (large slide glass white edge polishing No. 2 manufactured by Matsunami Glass Industry Co., Ltd.). The adhesive layer was cured on this laminate. In Example 25, in which the pressure-sensitive adhesive layer was thermosetting, the laminate was heat-treated at 150 ° C. for 10 minutes to cure the pressure-sensitive adhesive layer. In Examples 23 and 24 in which the pressure-sensitive adhesive layer is photocurable, an ultra-high pressure mercury lamp is irradiated from the glass support surface of the laminate at an intensity of 20 mW / cm ² for 150 seconds, and heat treatment is performed at 150 ° C. for 10 minutes. The pressure-sensitive adhesive layer was cured. Then, heat treatment at 280 ° C. for 60 minutes was performed once.
During the heat treatment, the time until the adhesive tape floated at the interface of either the glass support or the semiconductor wafer was measured and used as the peeling time. The case where the peeling time was within 5 minutes was shown as x, the case where the peeling time exceeded 5 minutes and was within 60 minutes was shown as ◯, and the case where the peeling time exceeded 60 minutes was shown as ⊚.
The interface after the adhesive tape was peeled off was visually observed to evaluate the residue. The case where the residue was found on the adherend was marked with ×, the case where the residue was found only on the edge portion of the adherend was marked with ◯, and the case where no residue was found was marked with ⊚.

(2) Evaluation of initial adhesive strength The adhesive tape was cut into a width of 25 mm. Glass (Large slide glass white edge polishing No. 2 manufactured by Matsunami Glass Industry Co., Ltd.) using a 2 kg pressure-bonded rubber roller to cut the adhesive tape in an environment with a room temperature of 23 ° C and a relative humidity of 50% at a speed of 10 mm / sec. I pasted it on. After standing for 30 minutes, the adhesive tape was peeled off at a speed of 300 mm / min according to JIS Z0237, and the peeling strength was measured at 180 degrees. In Examples 23 to 25, the initial adhesive strength of the pressure-sensitive adhesive layer 1 was measured using glass (manufactured by Matsunami Glass Industry Co., Ltd., large slide glass white edge polishing No. 2) as an adherend, and the pressure-sensitive adhesive layer 2 was measured. The initial adhesive strength was measured using a silicon mirror wafer as an adherend.

(3) Evaluation of Adhesive Strength after Heating Laminated body in the same manner as (1-1) High temperature (280 ° C) peeling evaluation of single-sided adhesive tape and (1-2) High temperature (280 ° C) peeling evaluation of double-sided adhesive tape. Was prepared, the pressure-sensitive adhesive layer was cured, and then the heat treatment was performed once at 280 ° C. for 60 minutes. After allowing to cool, the adhesive tape was peeled off at a speed of 300 mm / min and the peeling strength was measured at 180 degrees in accordance with JIS Z0237 as in the evaluation of the initial adhesive strength in (2) above.

(4) Post-Gas Adhesive Force For Examples 21 to 25, the post-gas generation adhesive strength of the pressure-sensitive adhesive layer containing the gas generating agent was measured.
A laminate was prepared in the same manner as in the above (1-1) evaluation of high temperature (280 ° C.) peeling of the single-sided adhesive tape and the above (1-2) evaluation of high temperature (280 ° C.) peeling of the double-sided adhesive tape, and the pressure-sensitive adhesive layer was cured. The treatment was performed, and then the heat treatment at 280 ° C. for 60 minutes was performed once. After allowing to cool, ultraviolet rays having a wavelength of 254 nm were irradiated from the base material surface of the adhesive tape or the surface of the adhesive layer 2 so that the integrated intensity was 12000 mJ / cm ^2, and a gas was generated. Then, in accordance with JIS Z0237 as in the above evaluation of the initial adhesive strength (2), the adhesive tape was peeled off at a speed of 300 mm / min, and the peeling strength was measured at 180 degrees.

Details of the materials listed in Tables 3-6 are shown below.
(A) Silicone compound Epoxy-modified silicone oil (X-22-163C, manufactured by Shin-Etsu Chemical Co., Ltd.)
Carbinol-modified silicone oil (KF-6000, manufactured by Shin-Etsu Chemical Co., Ltd.)

(B) Polymerization Initiator Thermal Polymerization Initiator (Perbutyl O, manufactured by NOF CORPORATION)
Photopolymerization Initiator (Omnirad 369, manufactured by IGM Resins)

(C) Crosslinking agent Isocyanate-based crosslinking agent (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.)
Epoxy cross-linking agent (Tetrad C, manufactured by Mitsubishi Gas Chemical Company)

According to the present invention, it is possible to provide a curable pressure-sensitive adhesive composition capable of forming a pressure-sensitive adhesive layer that is difficult to peel off even at a high temperature during the processing process of an adherend and can be easily peeled off after the process is completed. Further, according to the present invention, it is possible to provide an adhesive tape having an adhesive layer containing the curable pressure-sensitive adhesive composition, a method for processing a semiconductor wafer using the adhesive tape, and a method for manufacturing a semiconductor device. it can.

Claims (21)

A curable pressure-sensitive adhesive composition containing a (meth) acrylic copolymer and a polymerization initiator.
In addition, it contains a silicone compound
The (meth) acrylic copolymer is a curable pressure-sensitive adhesive composition having a structural unit represented by the following general formula (1) and a structural unit derived from a hydroxyl group-containing monomer.

In the general formula (1), R ¹ represents a hydrocarbon group, an ether bond-containing group or an ester bond-containing group, R ² represents a group containing two or more groups containing a radically polymerizable unsaturated bond, and R ⁵ Represents a hydrogen or methyl group. The curable pressure-sensitive adhesive composition according to claim 1, wherein the (meth) acrylic copolymer further contains a structural unit derived from a carboxyl group-containing monomer. In the (meth) acrylic copolymer, the structural unit derived from the hydroxyl group-containing monomer is a structural unit represented by the following general formula (2), and the structural unit derived from the carboxyl group-containing monomer is the following general formula ( The curable pressure-sensitive adhesive composition according to claim 2, further comprising a structural unit represented by the following general formula (4), which is a structural unit represented by 3).

In the general formula (2), R ⁴ represents a hydrocarbon group, an ether bond-containing group or an ester bond-containing group, and R ⁵ represents a hydrogen or methyl group.

In the general formula (3), R ⁵ represents a hydrogen or methyl group.

In the general formula (4), R ³ represents a hydrocarbon group, an ether bond-containing group or an ester bond-containing group, and R ⁵ represents a hydrogen or methyl group. The curability according to claim 2 or 3, wherein the (meth) acrylic copolymer has a content of a structural unit derived from the carboxyl group-containing monomer of 0.1 mol% or more and 5 mol% or less. Adhesive composition. Claims 1, 2 , 3 or 4 are characterized in that the content of the structural unit represented by the general formula (1) is 2 mol% or more and 25 mol% or less in the (meth) acrylic copolymer. The curable pressure-sensitive adhesive composition according to the above. Claims 1, 2 , 3 , 4 or the above-mentioned (meth) acrylic copolymer are characterized in that the content of the structural unit derived from the hydroxyl group-containing monomer is 0.1 mol% or more and 20 mol% or less. 5. The curable pressure-sensitive adhesive composition according to 5 . The curable pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5 or 6, wherein the (meth) acrylic copolymer has a weight average molecular weight of 300,000 or more and 2 million or less. The curable pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the weight loss rate after heating at 280 ° C. for 1 hour is 15% by weight or less. The curable pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7 or 8, wherein the tin component content is 0.05% by weight or less in terms of tin. Further, characterized by containing a cross-linking agent, said silicone compound has a crosslinkable functional group, the crosslinking agent having a (meth) acrylic copolymer and the silicone compound and crosslinkable functional groups The curable pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9. The silicone compound is a silicone-based graft copolymer, and the content of the silicone-based graft copolymer is 0.1 to 10 parts by weight with respect to 100 parts by weight of the (meth) acrylic copolymer. 10. The curable pressure-sensitive adhesive composition according to claim 10. The curable pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 or 11, wherein the polymerization initiator is a thermal polymerization initiator. An adhesive tape comprising a pressure-sensitive adhesive layer containing the curable pressure-sensitive adhesive composition according to claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12. 13. The adhesive tape according to claim 13, further comprising a base material and the pressure-sensitive adhesive layer laminated on both surfaces of the base material. The pressure-sensitive adhesive tape according to claim 14, wherein at least one of the pressure-sensitive adhesive layers contains a gas generating agent. The adhesive tape according to claim 15, wherein the gas generating agent contains a tetrazole compound or a salt thereof. The adhesive tape according to claim 14, 15 or 16, wherein at least one of the pressure-sensitive adhesive layers is thermosetting. The adhesive tape according to claim 14, 15 or 16, wherein all of the pressure-sensitive adhesive layers are ultraviolet-curable, and the ultraviolet-transmittance of the adhesive tape is 30% or more. The adhesive tape according to claim 13, 14, 15, 16, 17 or 18, which is used in a semiconductor processing process. A method for processing a semiconductor wafer using the adhesive tape according to claim 13, 14, 15, 16, 17, 18 or 19.
A temporary fixing step of temporarily fixing the semiconductor wafer on the adhesive tape and
A semiconductor wafer processing step in which the surface of the semiconductor wafer is treated with heating of 250 ° C. or higher,
A method for processing a semiconductor wafer, which comprises an adhesive tape peeling step of peeling the adhesive tape from the semiconductor wafer. A method for manufacturing a semiconductor device using the adhesive tape according to claim 14, 15, 16, 17, 18 or 19.
A temporary fixing step of temporarily fixing the semiconductor wafer on the support via the adhesive tape, and
A semiconductor wafer processing step in which the surface of the semiconductor wafer is treated with heating of 250 ° C. or higher,
A method for manufacturing a semiconductor device, which comprises a pressure-sensitive adhesive tape peeling step of peeling the pressure-sensitive adhesive tape from the support, the semiconductor wafer, or both.