WO2016121488A1

WO2016121488A1 - Adhesive sheet for semiconductor processing

Info

Publication number: WO2016121488A1
Application number: PCT/JP2016/050702
Authority: WO
Inventors: 泰史藤本; 沙也香坂東; 康彦垣内; 雄一朗小升
Original assignee: リンテック株式会社
Priority date: 2015-01-30
Filing date: 2016-01-12
Publication date: 2016-08-04
Also published as: CN107207920A; JPWO2016121488A1; KR20170108014A; SG11201706108UA; KR102510144B1; JP6566365B2; CN107207920B; TW201700666A; TWI753851B

Abstract

An adhesive sheet for use in semiconductor processing, having an intermediate layer and an adhesive layer on a substrate in this order, and satisfying the conditions that (a) the loss tangent of the intermediate layer when measured at a frequency of 1Hz at 50°C is 1.0 or higher, and (b) the ratio (A/I) of the storage elastic modulus A of the adhesive layer to the storage elastic modulus I of the intermediate layer when measured at a frequency of 1Hz at 50°C is 1.8 or less.

Description

Adhesive sheet for semiconductor processing

The present invention relates to a semiconductor processing pressure-sensitive adhesive sheet, and more particularly to a semiconductor processing pressure-sensitive adhesive sheet suitable for use in protecting the surface of a bumped semiconductor wafer.

As information terminal devices are rapidly becoming thinner, smaller, and multifunctional, semiconductor devices mounted on them are also required to be thinner and denser. In order to reduce the thickness of an apparatus, it is desired to reduce the thickness of a semiconductor wafer on which semiconductors are integrated. In order to meet the demand, the back surface of the semiconductor wafer is ground to reduce the thickness.

In recent years, bumps (electrodes) made of solder or the like having a height of about 30 μm to 100 μm are sometimes formed on the surface of a semiconductor wafer. When such a semiconductor wafer with bumps is subjected to back grinding, a back grind sheet (hereinafter also referred to as “BG sheet”) is attached to protect the surface having the bump portions.
However, a generally used BG sheet has a difference in height between a portion where bumps are present and a portion where bumps are not present on the surface after application, and is difficult to be flat. The pressure difference due to the height difference directly affects the back surface of the wafer, and when grinding the back surface of the wafer, dimples (chips, dents) and cracks (cracks) may occur, which may damage the semiconductor wafer obtained after grinding. .

For such a problem, for example, Patent Document 1 discloses a semiconductor wafer surface protection sheet including a resin layer (A) prepared so that the storage elastic modulus at 25 ° C. and 60 ° C. falls within a specific range. Has been. The semiconductor wafer surface protecting sheet is provided with a resin layer (A) having a drop in storage elastic modulus at room temperature (25 ° C.) and storage elastic modulus at high temperature (60 ° C.). By adopting such a configuration, the resin layer (A) is softened by sticking to a wafer surface having an uneven portion at a high temperature to absorb the uneven portion on the wafer surface, thereby reducing the height difference of the wafer surface. Yes.
Patent Document 2 discloses a pressure-sensitive adhesive tape for protecting a semiconductor wafer surface having a specific pressure-sensitive adhesive layer on a base film. The adhesive tape for surface protection of a semiconductor wafer is a pressure-sensitive adhesive whose adhesive layer does not contain an isocyanate-based or epoxy-based crosslinking agent, the thickness of the adhesive, the contact angle with diiodomethane, and 23 with respect to the SUS280 polished surface. Pressure-sensitive adhesive having a specific value with an adhesive strength at 50 ° C., and an adhesive strength with respect to a SUS280 polished surface at 50 ° C. during heat-release at 50 ° C. or less compared to the adhesive strength at release at 23 ° C. It is as a layer. By adopting such a configuration, an attempt is made to realize a semiconductor wafer surface protecting adhesive tape that prevents dust and water from entering during wafer polishing and can be easily peeled without damaging the wafer.

Japanese Patent No. 4603578 Japanese Patent No. 5138102

However, as in Patent Document 1, merely reducing the storage elastic modulus of the resin layer at a high temperature does not provide sufficient absorbability of the bump portion. In particular, since the effect of suppressing the gap generated between the bump portion and the BG sheet is insufficient, there is a concern that water used during grinding may enter the wafer surface during grinding of the wafer. Further, the relationship between the resin layer (A) and other resin layers is not described.
In Patent Document 2, evaluation is performed using a wafer in which a scribe line made of a polyimide film is formed on the wafer surface, but evaluation using a wafer with bumps is not described. Moreover, the adhesive wafer layer protects the semiconductor wafer surface with a level | step difference, Comprising: The relationship with layers other than an adhesive layer is not described.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an adhesive sheet for semiconductor processing that is excellent in the absorbability of bumps of a semiconductor wafer.

As a result of intensive studies, the present inventors have found that the semiconductor processing pressure-sensitive adhesive sheet has an intermediate layer having a loss tangent at 50 ° C. measured at a frequency of 1 Hz on the substrate, and a pressure-sensitive adhesive layer in this order. The ratio [A / I] of the storage elastic modulus A of the pressure-sensitive adhesive layer and the storage elastic modulus I of the intermediate layer at 50 ° C. measured at 1 Hz is within a specific range, so that the above problem can be solved. The headline and the present invention were completed.
That is, the present invention provides the following [1] to [10].
[1] A pressure-sensitive adhesive sheet for semiconductor processing, having an intermediate layer and a pressure-sensitive adhesive layer in this order on a substrate and satisfying the following (a) and (b).
(A) The loss tangent of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz is 1.0 or more. (B) The storage elastic modulus A of the pressure-sensitive adhesive layer and the storage elastic modulus of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz. Ratio [A / I] with I is 1.8 or less. [2] Ratio [A / I] of the storage elastic modulus A of the pressure-sensitive adhesive layer and the storage elastic modulus I of the intermediate layer at 50 ° C. measured at the frequency of 1 Hz. The adhesive sheet for semiconductor processing according to (1), wherein is 1.0 or less.
[3] The adhesive sheet for semiconductor processing according to the above [1] or [2], wherein the intermediate layer is formed from a resin composition containing urethane (meth) acrylate and a thiol group-containing compound.
[4] The adhesive sheet for semiconductor processing according to any one of [1] to [3], wherein the storage elastic modulus I of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz is 1.0 × 10 ⁶ Pa or less. .
[5] The adhesive sheet for semiconductor processing according to any one of [1] to [4], wherein the intermediate layer has a thickness of 50 to 400 μm.
[6] The adhesive sheet for semiconductor processing according to any one of [1] to [5], wherein the adhesive layer is formed from an acrylic adhesive, a rubber adhesive, or a urethane adhesive.
[7] The pressure-sensitive adhesive sheet for semiconductor processing according to [6], wherein the acrylic pressure-sensitive adhesive, rubber pressure-sensitive adhesive, or urethane pressure-sensitive adhesive is an energy ray curable pressure-sensitive adhesive.
[8] The acrylic copolymer containing 50 to 98% by mass of an alkyl (meth) acrylate having 4 or more carbon atoms in the alkyl group as a copolymer component based on the total amount of the copolymer component. The pressure-sensitive adhesive sheet for semiconductor processing according to [6] or [7], comprising a polymer.
[9] The above [6] or [7], wherein the acrylic pressure-sensitive adhesive contains a resin having a weight average molecular weight of 800,000 or more obtained by introducing an energy ray polymerizable functional group into an acrylic copolymer. Adhesive sheet for semiconductor processing.
[10] A method for attaching and protecting the adhesive sheet for semiconductor processing according to any one of [1] to [9] on the surface of a semiconductor wafer.

According to the present invention, it is possible to provide an adhesive sheet for semiconductor processing that is excellent in the absorbability of bumps of a semiconductor wafer.

It is sectional drawing which shows an example of a structure of the adhesive sheet for semiconductor processing of this invention.

In the description herein, “weight average molecular weight (Mw)”, “number average molecular weight (Mn)” and “molecular weight distribution (Mw / Mn)” are measured by gel permeation chromatography (GPC). It is a value in terms of standard polystyrene, specifically a value measured based on the method described in the examples.
In the description of the present specification, for example, “(meth) acrylate” is a term meaning both “acrylate” and “methacrylate”, and the same applies to other similar terms.
Further, in the description in the present specification, for example, “energy beam” is a term that means a known energy beam such as γ-ray, electron beam, ultraviolet ray, and visible light.
Moreover, the thickness of the base material which comprises the adhesive sheet for semiconductor processing mentioned later, an intermediate | middle layer, an adhesive layer, and the peeling material provided arbitrarily is the value measured with the constant-pressure thickness measuring device.

[Semiconductor processing adhesive sheet]
The pressure-sensitive adhesive sheet for semiconductor processing of the present invention is applied to protect a semiconductor wafer, in particular, to protect a surface having a bump portion of a semiconductor wafer with bumps (hereinafter, also simply referred to as “the surface of a wafer with bumps”). It is used to protect. As shown in FIG. 1, the pressure-sensitive adhesive sheet 10 for semiconductor processing of the present invention has an intermediate layer 2 and a pressure-sensitive adhesive layer 1 in this order on a base material 3, and the following requirements (a) and (b): It is an adhesive sheet for semiconductor processing that satisfies.
(A) The loss tangent of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz is 1.0 or more. (B) The storage elastic modulus A of the pressure-sensitive adhesive layer and the storage elastic modulus of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz. Ratio [A / I] with I is 1.8 or less

The pressure-sensitive adhesive sheet for semiconductor processing of the present invention has an intermediate layer having a loss tangent (tan δ) (hereinafter also simply referred to as “loss tangent of intermediate layer”) at 50 ° C. measured at a frequency of 1 Hz of 1.0 or more. When the loss tangent of the intermediate layer is less than 1.0, the intermediate layer is not sufficiently deformed and cannot follow the bump when the semiconductor processing pressure-sensitive adhesive sheet of the present invention is applied to the surface of the bumped wafer. From the standpoint that the intermediate layer sufficiently absorbs the bumps and obtains a good sticking state on the surface of the wafer with bumps, the loss tangent of the intermediate layer is preferably 1.5 or more, more preferably 1.8 or more, and still more preferably. Is 2.0 or more, more preferably 3.0 or more.
Further, from the viewpoint of adjusting the fluidity during heating of the intermediate layer to an appropriate range, the loss tangent of the intermediate layer is preferably 5.0 or less, more preferably 4.0 or less.
The above-mentioned loss tangent of the intermediate layer is more specifically a value measured based on the method described in Examples described later.

The pressure-sensitive adhesive sheet for semiconductor processing of the present invention has a storage elastic modulus A of the pressure-sensitive adhesive layer at 50 ° C. measured at a frequency of 1 Hz described later, and a storage elastic modulus I of an intermediate layer at 50 ° C. measured at a frequency of 1 Hz described later. The pressure-sensitive adhesive layer and the intermediate layer have a ratio [A / I] (hereinafter, also simply referred to as “storage elastic modulus ratio [A / I]”) of 1.8 or less.
If the storage elastic modulus ratio [A / I] exceeds 1.8, the pressure-sensitive adhesive layer is not deformed to the extent that it can follow the bumps, and the bump absorbability of the semiconductor processing pressure-sensitive adhesive sheet is poor. That is, even when the adhesive sheet for semiconductor processing has only a flexible intermediate layer, if the outermost adhesive layer is more rigid than the intermediate layer, the adhesive sheet for semiconductor processing has sufficient bumps. Unable to follow. The storage elastic modulus ratio [A / I] is preferably 1.5 or less from the viewpoint that the bumps can be sufficiently absorbed and pasted and the surface of the adhesive sheet for semiconductor processing after pasting can be smoothed. Preferably it is 1.0 or less, More preferably, it is 0.5 or less. In particular, when the storage elastic modulus ratio [A / I] is 1.0 or less, the surface of the adhesive sheet for semiconductor processing after being attached to the surface of the wafer with bumps can be kept smoother.
Further, from the viewpoint of facilitating maintaining the flexibility of the intermediate layer to a higher degree or maintaining the cohesiveness of the pressure-sensitive adhesive layer, the ratio of the storage elastic modulus [A / I] is preferably 0.05 or more, more preferably 0.1 or more, and further preferably 0.15 or more.
The storage elastic modulus A of the pressure-sensitive adhesive layer at 50 ° C. measured at a frequency of 1 Hz and the storage elastic modulus I of the intermediate layer measured at 50 ° C. at a frequency of 1 Hz are more specifically described in the examples described later. It is the value measured based on the described method.
Hereinafter, each member of the adhesive sheet for semiconductor processing will be described.

<Base material>
Although the base material used in the present invention is not particularly limited, it is a resin film from the viewpoint that it is suitable for a processed member of electronic parts because it generates less dust compared to paper and non-woven fabric, and is easily available. Is preferred. By providing the base material on the adhesive sheet for semiconductor processing, the shape stability of the adhesive sheet for semiconductor processing can be improved, or the stiffness can be given to the adhesive sheet for semiconductor processing. Further, when the semiconductor processing adhesive sheet is attached to the adherend surface on which the bumps are present, the surface opposite to the application surface of the semiconductor processing adhesive sheet is likely to be kept smooth.
The substrate used in the present invention may be a substrate made of a single layer film made of one resin film, or may be a substrate made of a multilayer film in which a plurality of resin films are laminated.
The thickness of the base material is preferably 5 to 250 μm, more preferably 10 to 10 μm, from the viewpoint of giving an appropriate elasticity to the semiconductor processing pressure-sensitive adhesive sheet and from the viewpoint of handling at the time of winding the semiconductor processing pressure-sensitive adhesive sheet. It is 200 μm, more preferably 25 to 150 μm.

Examples of the resin film used as the substrate of the present invention include a polyolefin film, a vinyl halide polymer film, an acrylic resin film, a rubber film, a cellulose film, a polyester film, a polycarbonate film, and a polystyrene film. , A polyphenylene sulfide film, a cycloolefin polymer film, a film made of a cured product of an energy ray curable composition containing a urethane resin, and the like.
Among these, from the viewpoint that the workpiece can be stably held even when grinding a workpiece such as a wafer to an extremely thin thickness, a film having a high thickness accuracy is preferable. Specifically, a polyester film or a polycarbonate film. A polystyrene film, a polyphenylene sulfide film, a cycloolefin polymer film, a film made of a cured product of an energy ray curable composition containing a urethane resin, and the like are preferable, and a polyester film is more preferable.

As polyester which comprises a polyester-type film, the polyester obtained by polycondensing from an aromatic dibasic acid or its ester derivative, and diol or its ester derivative is mentioned, for example.
Specific examples of the polyester film include films made of polyester such as polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalenedicarboxylate.
The polyester film used in the present invention may be a film made of a polyester copolymer or a resin mixed film made of a mixture of the polyester and a relatively small amount of another resin.
Among these polyester-based films, a polyethylene terephthalate film is preferred from the viewpoint of easy availability and high thickness accuracy.

In addition, you may use the base material which laminated | stacked the primer layer or the adhesive layer further on the surface of the resin film from a viewpoint of improving the adhesiveness of a base material and an intermediate | middle layer.
Furthermore, the base material used in the present invention may contain a filler, a colorant, an antistatic agent, an antioxidant, an organic lubricant, a catalyst and the like as long as the effects of the present invention are not impaired.
Further, the substrate may be transparent or opaque, and may be colored or vapor-deposited as desired.
When the semiconductor processing pressure-sensitive adhesive sheet has a pressure-sensitive adhesive layer to be described later, and the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is an energy ray-curable pressure-sensitive adhesive, the base material has a sufficient degree to cure the pressure-sensitive adhesive. Those that transmit energy rays are preferred.

<Intermediate layer>
The intermediate layer used in the present invention is not particularly limited as long as it satisfies the above requirements (a) and (b). However, from the viewpoint of easily satisfying the requirements and obtaining better bump absorbability, urethane (meta It is preferably formed from a resin composition containing an acrylate and a thiol group-containing compound.
The intermediate layer has a storage elastic modulus I of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz, preferably 1.0 × 10 ⁶ Pa or less, from the viewpoint of obtaining a better sticking state on the wafer with bumps. Preferably it is 5.0 * 10 < ⁵ > Pa or less, More preferably, it is 2.0 * 10 < ⁵ > Pa or less.
Further, from the viewpoint of providing appropriate bump absorbability, the storage elastic modulus I of the intermediate layer is preferably 1.0 × 10 ⁴ Pa or more, more preferably 5.0 × 10 ⁴ Pa or more, and further preferably 7. 0 × 10 ⁴ Pa or more.
In addition, the thickness of the intermediate layer can be appropriately adjusted according to the bump height on the surface of the semiconductor to be protected, but it is preferable from the viewpoint that a relatively high bump can be absorbed. Is 50 to 400 μm, more preferably 70 to 300 μm, still more preferably 80 to 250 μm.
Hereinafter, details of each component contained in the resin composition (hereinafter, also simply referred to as “interlayer resin composition”) will be described.

(Urethane (meth) acrylate)
Urethane (meth) acrylate is a compound having at least a (meth) acryloyl group and a urethane bond, and has a property of being polymerized by irradiation with energy rays.
The number of (meth) acryloyl groups in the urethane (meth) acrylate may be monofunctional, bifunctional, or trifunctional or higher, but from the viewpoint of forming an intermediate layer satisfying the above requirement (a), the monofunctional urethane (meth) acrylate It is preferable to contain.
When a monofunctional urethane (meth) acrylate is included in the film-forming composition, the monofunctional urethane (meth) acrylate does not participate in the formation of the three-dimensional network structure in the polymerized structure, so that the three-dimensional network structure is hardly formed. In particular, it is easy to form an intermediate layer that satisfies the requirement (a).
Examples of the urethane (meth) acrylate used in the resin composition for an intermediate layer include, for example, a (meth) acrylate having a hydroxyl group in a terminal isocyanate urethane prepolymer obtained by reacting a polyol compound and a polyvalent isocyanate compound. Can be obtained by reacting.
Urethane (meth) acrylate may be used alone or in combination of two or more.

[Polyol compound]
The polyol compound is not particularly limited as long as it is a compound having two or more hydroxy groups.
Specific examples of the polyol compound include alkylene diol, polyether type polyol, polyester type polyol, and polycarbonate type polyol.
Among these, polyether type polyols are preferable.
The polyol compound may be a bifunctional diol, a trifunctional triol, or a tetrafunctional or higher polyol, but from the viewpoint of availability, versatility, reactivity, etc., a bifunctional diol Are preferred, and polyether type diols are more preferred.

The polyether type diol is preferably a compound represented by the following formula (1).

In the above formula (1), R is a divalent hydrocarbon group, preferably an alkylene group, more preferably an alkylene group having 1 to 6 carbon atoms. Among the alkylene groups having 1 to 6 carbon atoms, an ethylene group, a propylene group, and a tetramethylene group are preferable, and a propylene group and a tetramethylene group are more preferable.
N is the number of repeating units of alkylene oxide, preferably 10 to 250, more preferably 25 to 205, and still more preferably 40 to 185. If n is the said range, it will become easy to prepare an intermediate | middle layer so that the urethane bond density | concentration of the urethane (meth) acrylate obtained may be moderated and the said requirements (a) may be satisfy | filled.
Among the compounds represented by the formula (1), polyethylene glycol, polypropylene glycol, and polytetramethylene glycol are preferable, and polypropylene glycol and polytetramethylene glycol are more preferable.
A terminal isocyanate urethane prepolymer having an ether bond [-(-RO-) n-] introduced therein is produced by a reaction between a polyether-type diol and a polyvalent isocyanate compound. By using such a polyether type diol, the urethane (meth) acrylate contains a structural unit derived from the polyether type diol.

As the polybasic acid component used for the production of the polyester type polyol, a compound generally known as a polybasic acid component of polyester can be used.
Specific examples of the polybasic acid component include dibasic acids such as adipic acid, maleic acid, succinic acid, oxalic acid, fumaric acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid, and suberic acid; Dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, aromatic polybasic acids such as polybasic acids such as trimellitic acid and pyromellitic acid, anhydrides corresponding to these, The derivative | guide_body, dimer acid, hydrogenated dimer acid, etc. are mentioned.
Among these, an aromatic polybasic acid is preferable from the viewpoint of forming a coating film having an appropriate hardness.
Various known catalysts may be used in the esterification reaction for producing the polyester-type polyol, if necessary.
Examples of the catalyst include tin compounds such as dibutyltin oxide and stannous octylate, and alkoxytitanium such as tetrabutyl titanate and tetrapropyl titanate.
The polycarbonate type polyol is not particularly limited, and examples thereof include a reaction product of the above-described glycols and alkylene carbonate.

The number average molecular weight calculated from the hydroxyl value of the polyol compound is preferably 1,000 to 10,000, more preferably 2,000 to 9,000, and still more preferably 3,000 to 7,000. If the number average molecular weight is 1,000 or more, it is preferable because a situation in which it becomes difficult to control the viscoelastic properties of the intermediate layer due to the generation of an excessive amount of urethane bonds is avoided. On the other hand, if the number average molecular weight is 10,000 or less, it is preferable because the obtained intermediate layer can be prevented from being excessively softened.
The number average molecular weight calculated from the hydroxyl value of the polyol compound is a value calculated from [number of polyol functional groups] × 56.11 × 1,000 / [hydroxyl value (unit: mgKOH / g)].

[Polyisocyanate compound]
Examples of the polyvalent isocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; isophorone diisocyanate, norbornane diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, dicyclohexylmethane-2 , 4'-diisocyanate, ω, ω'-diisocyanate dimethylcyclohexane, etc .; 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, tolidine diisocyanate, tetramethylene xylylene diisocyanate, naphthalene- And aromatic diisocyanates such as 1,5-diisocyanate.
Among these, isophorone diisocyanate, hexamethylene diisocyanate, and xylylene diisocyanate are preferable from the viewpoint of handleability.

{(Meth) acrylate having a hydroxy group}
The (meth) acrylate having a hydroxy group is not particularly limited as long as it is a compound having a hydroxy group and a (meth) acryloyl group in at least one molecule.
Specific examples of the (meth) acrylate having a hydroxy group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and 4-hydroxycyclohexyl (meth). Acrylate, 5-hydroxycyclooctyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, pentaerythritol tri (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate, etc. Hydroxy-alkyl (meth) acrylates; hydroxy-group-containing (meth) acrylamides such as N-methylol (meth) acrylamide; vinyl alcohol, vinyl phenol, bisphenol The reaction product obtained by the diglycidyl ester of Nord A (meth) acrylic acid is reacted, and the like.
Among these, hydroxyalkyl (meth) acrylate is preferable, and 2-hydroxyethyl (meth) acrylate is more preferable.
The conditions for reacting the terminal isocyanate urethane prepolymer and the (meth) acrylate having a hydroxy group are preferably conditions of reacting at 60 to 100 ° C. for 1 to 4 hours in the presence of a solvent and a catalyst added as necessary. .

The urethane (meth) acrylate for the intermediate layer resin composition thus obtained may be an oligomer, a high molecular weight product, or a mixture thereof, but a urethane (meth) acrylate oligomer is preferred.
The weight average molecular weight of the urethane (meth) acrylate is preferably 1,000 to 100,000, more preferably 3,000 to 80,000, still more preferably 5,000 to 65,000. If the weight average molecular weight is 1,000 or more, in the polymer of urethane (meth) acrylate and a polymerizable monomer described later, due to the intermolecular force between the structures derived from urethane (meth) acrylate, This is preferable because moderate hardness is imparted to the intermediate layer.
The blending amount of the urethane (meth) acrylate in the intermediate layer resin composition is preferably 20 to 70% by mass, more preferably 25 to 60% by mass, still more preferably 30 to 50% by mass, and still more preferably 33 to 47% by mass. If the blending amount of urethane (meth) acrylate is in such a range, the intermediate layer satisfying the above requirement (a) is formed, and the storage elastic modulus I of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz is described above. It is easier to adjust to the range.

(Thiol group-containing compound)
The thiol group-containing compound is not particularly limited as long as it is a compound having at least one thiol group in the molecule, but it contains a polyfunctional thiol group from the viewpoint of easily forming an intermediate layer satisfying the above requirement (a). Compounds are preferred, and tetrafunctional thiol group-containing compounds are more preferred.
Specific examples of the thiol group-containing compound include nonyl mercaptan, 1-dodecanethiol, 1,2-ethanedithiol, 1,3-propanedithiol, triazinethiol, triazinedithiol, triazinetrithiol, 1,2,3- Propane trithiol, tetraethylene glycol-bis (3-mercaptopropionate), trimethylolpropane tris (3-mercaptopropionate), pentaerythritol tetrakis (3-mercaptopropionate), pentaerythritol tetrakisthioglucorate, Dipentaerythritol hexakis (3-mercaptopropionate), tris [(3-mercaptopropionyloxy) -ethyl] -isocyanurate, 1,4-bis (3-mercaptobutyryloxy) buta Pentaerythritol tetrakis (3-mercaptobutyrate), 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6- (1H, 3H, 5H)- A trion etc. are mentioned.
In addition, you may use these thiol group containing compounds 1 type or in combination of 2 or more types.

The molecular weight of the thiol group-containing compound is preferably 200 to 3,000, more preferably 300 to 2,000. If the said molecular weight is the said range, compatibility with urethane (meth) acrylate will become favorable and film forming property can be made favorable.
The amount of the thiol group-containing compound is preferably 1.0 to 4.9 parts by mass, more preferably 1.5 to 100 parts by mass with respect to 100 parts by mass in total of the urethane (meth) acrylate and the polymerizable monomer described later. 4.8 parts by mass.
If the said compounding quantity is 1.0 mass part or more, it will become easy to form the intermediate | middle layer which satisfy | fills the said requirements (a), and a pump absorptivity can be improved. On the other hand, if the said compounding quantity is 4.9 mass parts or less, the seepage of the intermediate | middle layer at the time of winding up in roll shape can be suppressed.

(Polymerizable monomer)
It is preferable that the resin composition for intermediate layers used in the present invention further contains a polymerizable monomer from the viewpoint of improving the film forming property.
The polymerizable monomer is a polymerizable compound other than the above urethane (meth) acrylate, and is a compound that can be polymerized with other components by irradiation with energy rays, excluding the resin component, and at least A compound having one (meth) acryloyl group is preferred.
In the present specification, the “resin component” refers to an oligomer or high molecular weight body having a repeating structure in the structure, and refers to a compound having a weight average molecular weight of 1,000 or more.

Examples of the polymerizable monomer include (meth) acrylate having an alkyl group having 1 to 30 carbon atoms, (meth) acrylate having a functional group such as a hydroxyl group, an amide group, an amino group, and an epoxy group, and an alicyclic structure. (Meth) acrylate having an aromatic structure, (meth) acrylate having a heterocyclic structure, styrene, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, N-vinylformamide, N-vinylpyrrolidone, N- Examples thereof include vinyl compounds such as vinyl caprolactam.

Examples of the (meth) acrylate having an alkyl group having 1 to 30 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) ) Acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, nonyl (Meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, hexadecyl (meth) acrylate, octadecyl ( Data) acrylate, eicosyl (meth) acrylate.

Examples of the (meth) acrylate having a functional group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3 Hydroxyl group-containing (meth) acrylates such as hydroxybutyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N- Amide group-containing compounds such as methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide; primary amino group-containing (meth) acrylate Amino group-containing (meth) acrylates such as secondary amino group-containing (meth) acrylate and tertiary amino group-containing (meth) acrylate; glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether, etc. Epoxy group-containing (meth) acrylate and the like.

Examples of the (meth) acrylate having an alicyclic structure include isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyloxy (meth) acrylate, and cyclohexyl (meth) ) Acrylate, adamantane (meth) acrylate and the like.
Examples of the (meth) acrylate having an aromatic structure include phenylhydroxypropyl (meth) acrylate, benzyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, and the like.
Examples of the (meth) acrylate having a heterocyclic structure include tetrahydrofurfuryl (meth) acrylate and morpholine (meth) acrylate.

Among these, those having a relatively bulky group are preferable from the viewpoint of compatibility with the urethane (meth) acrylate, and more specifically, (meth) acrylate having an alicyclic structure, aromatic structure. (Meth) acrylate having a heterocyclic structure and (meth) acrylate having a heterocyclic structure are preferable, and (meth) acrylate having an alicyclic structure is more preferable. In addition, from the viewpoint of obtaining a resin composition for an intermediate layer that easily forms an intermediate layer satisfying the requirement (a), the polymerizable monomer has a (meth) acrylate having a functional group and an alicyclic structure (meth). It is preferable that acrylate is included, and it is more preferable that hydroxypropyl (meth) acrylate and isobornyl (meth) acrylate are included.

From the above viewpoint, the amount of the (meth) acrylate having an alicyclic structure in the intermediate layer resin composition is preferably 32 to 53% by mass, more preferably 35 to 51% by mass, and still more preferably 37 to 48%. % By mass, still more preferably 40 to 47% by mass.
In addition, the blending amount of the (meth) acrylate having an alicyclic structure with respect to the total amount of the polymerizable monomer contained in the intermediate layer resin composition is preferably 52 to 87% by mass, more preferably from the above viewpoint. Is 55 to 85% by mass, more preferably 60 to 80% by mass, and still more preferably 65 to 77% by mass. When the blending amount of the (meth) acrylate having an alicyclic structure is in such a range, it is easier to adjust the storage elastic modulus I of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz to the above-described range. Become.

The blending amount of the polymerizable monomer in the intermediate layer resin composition is preferably 30 to 80% by mass, more preferably 40 to 75% by mass, still more preferably 50 to 70% by mass, and still more preferably. 53 to 67% by mass. If the blending amount of the polymerizable monomer is within such a range, the intermediate layer tends to be flexible because the mobility of the portion formed by polymerization of the polymerizable monomer in the intermediate layer is high, It becomes easier to form an intermediate layer satisfying the above requirement (a) and to adjust the storage elastic modulus I of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz to the above-described range.
From the same viewpoint, the mass ratio [urethane (meth) acrylate / polymerizable monomer] of urethane (meth) acrylate and polymerizable monomer in the resin composition for intermediate layer is preferably 20/80. -60/40, more preferably 30 / 70-50 / 50, still more preferably 35 / 65-45 / 55.

(Energy beam polymerization initiator)
When ultraviolet rays are used as energy rays to cure the coating film made of the intermediate layer resin composition and form the intermediate layer, the intermediate layer resin composition may further contain an energy ray polymerization initiator. preferable. Since the energy ray polymerization initiator is generally also referred to as a “photopolymerization initiator”, in the present specification, it is also simply referred to as a “photopolymerization initiator”.
Examples of the photopolymerization initiator include photopolymerization initiators such as benzoin compounds, acetophenone compounds, acylphosphinoxide compounds, titanocene compounds, thioxanthone compounds, and peroxide compounds, and photosensitizers such as amines and quinones. More specifically, for example, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, 2 , 2-dimethoxy-1,2-diphenylethane-1-one and the like.
These photopolymerization initiators may be used alone or in combination of two or more.
The blending amount of the photopolymerization initiator is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass in total of the urethane (meth) acrylate and the polymerizable monomer. More preferably, it is 0.3 to 5 parts by mass.

(Other additives)
The intermediate layer resin composition may contain other additives as long as the effects of the present invention are not impaired.
Examples of other additives include cross-linking agents, antioxidants, softeners (plasticizers), fillers, rust inhibitors, pigments, and dyes.
When these additives are blended, the blending amount of the other additives is preferably 0.01 to 6 parts by mass, more preferably 0 with respect to 100 parts by mass in total of the component (A) and the component (B). 1 to 3 parts by mass.
In addition, in the range which does not impair the effect of this invention, although the resin component for intermediate | middle layers may contain resin components other than urethane (meth) acrylate, it contains only urethane (meth) acrylate as a resin component. It is preferable.
The content of the resin component other than the urethane (meth) acrylate contained in the intermediate layer resin composition is preferably 5% by mass or less, more preferably 1% by mass or less, and still more preferably 0.1% by mass or less. More preferably 0% by mass

Moreover, as long as the intermediate layer satisfies the above requirements (a) and (b), in addition to the intermediate layer resin composition, the intermediate layer is polymerized with a non-reactive urethane polymer or oligomer. It may be formed using a cured product of a curable composition containing a curable monomer or an ethylene-α-olefin copolymer. As the non-reactive urethane polymer or oligomer, a known one may be used, and as the polymerizable monomer, the same one as described above can be used. Such a curable composition may contain the energy beam polymerization initiator mentioned above.

The ethylene-α-olefin copolymer is obtained by polymerizing ethylene and an α-olefin monomer. Examples of α-olefin monomers include propylene, 1-butene, 2-methyl-1-butene, 2-methyl-1-pentene, 1-hexene, 2,2-dimethyl-1-butene, and 2-methyl-1-hexene. 4-methyl-1-pentene, 1-heptene, 3-methyl-1-hexene, 2,2-dimethyl-1-pentene, 3,3-dimethyl-1-pentene, 2,3-dimethyl-1-pentene , 3-ethyl-1-pentene, 2,2,3-trimethyl-1-butene, 1-octene, 2,2,4-trimethyl-1-octene, and the like. These α-olefin monomers can be used alone or in combination of two or more.
In addition to the above monomers, other polymerizable monomers can also be used for the ethylene-α-olefin copolymer. Examples of other polymerizable monomers include vinyl compounds such as vinyl acetate, styrene, acrylonitrile, methacrylonitrile, and vinyl ketone; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; methyl acrylate, ethyl acrylate, acrylic Examples thereof include unsaturated carboxylic acid esters such as acid-n-propyl, methyl methacrylate, ethyl methacrylate, and methacrylic acid-n-propyl; unsaturated carboxylic acid amides such as acrylamide and methacrylamide. These polymerizable monomers can be used alone or in combination of two or more.

<Adhesive layer>
The pressure-sensitive adhesive sheet for semiconductor processing of the present invention further has a pressure-sensitive adhesive layer on the intermediate layer, so that the pressure-sensitive adhesive sheet can be reliably fixed and protected on the surface of the semiconductor wafer, particularly the surface of the wafer with bumps.
If the pressure-sensitive adhesive layer used in the present invention is a pressure-sensitive adhesive layer satisfying the above requirement (b), the type of pressure-sensitive adhesive (hereinafter also simply referred to as “pressure-sensitive adhesive composition”) constituting the pressure-sensitive adhesive layer is not limited. .
Examples of such adhesives include acrylic adhesives, rubber adhesives, urethane adhesives, silicone adhesives, polyvinyl ether adhesives, and olefin adhesives.
These pressure-sensitive adhesives may be used alone or in combination of two or more.
The pressure-sensitive adhesive layer has a storage elastic modulus A at 50 ° C. measured at the frequency of 1 Hz of 1.8 × 10 ⁶ Pa or less from the viewpoint of obtaining a pressure-sensitive adhesive layer satisfying the requirement (b). Preferably, it is 1.0 × 10 ⁶ Pa or less, more preferably 1.0 × 10 ⁵ Pa or less, and even more preferably 9.0 × 10 ⁴ Pa or less.
Further, from the viewpoint of stabilizing the thickness of the pressure-sensitive adhesive layer and preventing the pressure-sensitive adhesive layer from protruding from the end surface of the semiconductor processing sheet, the storage elastic modulus A of the pressure-sensitive adhesive layer is preferably 1. It is 0 × 10 ⁴ Pa or more, more preferably 2.5 × 10 ⁴ Pa or more.
The thickness of the pressure-sensitive adhesive layer can be appropriately adjusted according to the bump height of the semiconductor surface to be protected, but is preferably 5 to 200 μm, more preferably 7 to 150 μm, and still more preferably 10 to 100 μm.

(Acrylic adhesive)
The acrylic pressure-sensitive adhesive that can be used in the pressure-sensitive adhesive layer of the present invention is generally an acrylic pressure-sensitive adhesive including an acrylic copolymer, and the acrylic copolymer is hereinafter also referred to as “main polymer”. . The acrylic pressure-sensitive adhesive is a preferable pressure-sensitive adhesive from the viewpoint that it is easy to design a pressure-sensitive adhesive suitable for use by selecting various copolymer components of the acrylic copolymer.
The acrylic copolymer is obtained by copolymerizing a monomer component containing alkyl (meth) acrylate as a main monomer (hereinafter also referred to as “copolymer component”). Examples of the alkyl (meth) acrylate include those having 1 to 18 carbon atoms in the alkyl group, such as methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, and butyl. (Meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate Etc.
The acrylic copolymer preferably contains 50% by mass or more, more preferably 50 to 99% by mass of alkyl (meth) acrylate as a copolymer component with respect to the total amount of the copolymer component.

From the viewpoint of adjusting the storage elastic modulus A of the pressure-sensitive adhesive layer to a desired value, the acrylic copolymer is an alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms as the copolymer component. The (meth) acrylate is preferably contained in an amount of 50 to 98% by mass based on the total amount of the copolymer components. By making content of the alkyl (meth) acrylate whose carbon number of an alkyl group is 4 or more into such a range, it becomes easy to provide suitable adhesive performance and peeling performance to a surface protection film. From such a viewpoint, the content of the alkyl (meth) acrylate having 4 or more carbon atoms in the alkyl group is more preferably 70 to 97% by mass, and still more preferably 80 to 96% by mass.
The alkyl (meth) acrylate having 4 or more carbon atoms in the alkyl group is preferably an alkyl (meth) acrylate in which the alkyl group has 4 to 8 carbon atoms, and the alkyl group has 6 to 8 carbon atoms. Alkyl (meth) acrylates are more preferred, and alkyl acrylates having an alkyl group with 6 to 8 carbon atoms are even more preferred. Specifically, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate and the like are preferable.

The acrylic copolymer preferably contains a polymerizable monomer other than alkyl (meth) acrylate as the copolymer component, and specifically contains a functional group-containing monomer. The functional group-containing monomer provides a functional group necessary for the reaction with a compound having both a reactive group capable of binding to the functional group described later and an energy ray polymerizable functional group and / or a crosslinking agent described later. To do. The functional group-containing monomer is a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, and an epoxy group in the molecule.
The acrylic copolymer is preferably a copolymer component obtained by copolymerizing a copolymer component containing 0.1 to 40% by mass of a functional group-containing monomer with respect to the total amount of the copolymer component. When the content of the functional group-containing monomer is within the above range, the acrylic copolymer can be appropriately crosslinked with a crosslinking agent described later.
The content of the functional group-containing monomer is more preferably 0.2 to 30% by mass. When the functional group-containing monomer is 0.2 to 30% by mass, it is possible to appropriately crosslink the acrylic copolymer with a cross-linking agent to be described later while ensuring appropriate adhesive performance.

Here, examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, and itaconic acid.
Specific examples of the hydroxyl group-containing (meth) acrylate include hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2 -Hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and the like.
Moreover, as a monomer which has an epoxy group in a molecule | numerator, glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, allyl glycidyl ether etc. are mentioned, for example.
The above functional group-containing monomers may be used alone or in combination of two or more.

In addition to the above monomers, the acrylic copolymer is a copolymer of (meth) acrylic acid esters, dialkyl (meth) acrylamides, vinyl formate, vinyl acetate, and styrene other than alkyl (meth) acrylate and functional group-containing monomers. It may be included as a coalescence component. As (meth) acrylic acid esters other than (meth) acrylic acid alkyl esters and functional group-containing monomers, (meth) acrylic acid alkoxyalkyl esters, (meth) acrylic acid alkyleneoxyalkyl esters, (meth) acrylic acid nonylphenoxy polyethylene Glycol, tetrahydrofuran furfuryl acrylate, diacrylates which are esters of polyether and acrylic acid, and the like may also be used.
As the dialkyl (meth) acrylamide, dimethyl (meth) acrylamide, diethyl (meth) acrylamide and the like are used.
The weight average molecular weight of the acrylic copolymer is usually 100,000 or more, preferably from the viewpoint of suppressing the adhesive residue on the surface of the bumped wafer when peeling off the adhesive sheet for semiconductor processing after use. 800,000 or more, more preferably 850,000 or more. Moreover, from a viewpoint of applicability | paintability, Preferably it is 1,500,000 or less. When the weight average molecular weight of the acrylic copolymer is in such a range, the abundance of the low molecular weight substance in the acrylic copolymer is kept low, and the cohesiveness of the pressure-sensitive adhesive layer is improved. As a result, it becomes easy to prevent the adhesive around the bumps from being peeled off by the force applied when the adhesive sheet for semiconductor processing is peeled off, resulting in generation of adhesive residue. On the other hand, when the weight average molecular weight of the acrylic copolymer is so large, the storage elastic modulus A of the pressure-sensitive adhesive layer tends to be high, and the storage elastic modulus I of the intermediate layer is low. Therefore, there is a concern that it is difficult for the pressure-sensitive adhesive sheet for semiconductor processing to satisfy the requirement (b). However, it becomes easy to adjust the storage elastic modulus A of the pressure-sensitive adhesive layer to a desired value by selecting the type and amount of the alkyl (meth) acrylate as the copolymer component as described above.
The acrylic pressure-sensitive adhesive can be used as an energy ray-curable pressure-sensitive adhesive that is cured by irradiation with energy rays and becomes removable.
In addition, the above-mentioned weight average molecular weight is a value measured based on the method described in the Example mentioned later more specifically.
When used as an energy ray-curable pressure-sensitive adhesive, the weight average molecular weight of a resin having an energy ray-polymerizable functional group introduced into an acrylic copolymer described later is the value after introducing the energy ray-polymerizable functional group. This is a value measured for an acrylic copolymer, and its preferred range is the same as the weight average molecular weight of the acrylic copolymer described above.

[Energy ray curable adhesive]
The energy ray curable pressure-sensitive adhesive refers to a pressure-sensitive adhesive that is cured by irradiation with energy rays.
The pressure-sensitive adhesive composition used for the energy ray-curable pressure-sensitive adhesive is a pressure-sensitive adhesive composition (X) containing an energy ray-curable compound together with the acrylic copolymer, or energy ray-polymerizable to the acrylic copolymer. And a pressure-sensitive adhesive composition (Y) containing a resin having a functional group introduced therein. In addition, when using the adhesive composition (Y) containing the resin which introduce | transduced the energy ray polymerizable functional group into the acrylic copolymer, the energy ray polymerizable functional group was introduced into the acrylic copolymer. A non-energy ray-polymerizable acrylic copolymer or an energy ray-curable compound may be used together with the resin. Among these, when the pressure-sensitive adhesive composition (Y) is used, sufficient energy beam curability can be exhibited even if the energy beam curable compound is not used or only a small amount is used. It is preferable because generation of adhesive residue on the adherend due to the energy beam curable compound can be suppressed.

As the energy ray-curable compound to be blended in the pressure-sensitive adhesive composition (X), a monomer or oligomer having an unsaturated group in the molecule and capable of being polymerized and cured by irradiation with energy rays is preferable. Examples of such energy ray curable compounds include trimethylolpropane tri (meth) acrylate, pentaerythritol (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,4- Polyvalent (meth) acrylate monomers such as butylene glycol di (meth) acrylate, 1,6-hexanediol (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate, epoxy ( And meth) acrylates and oligomers thereof.
The molecular weight of the energy ray-curable compound (weight average molecular weight in the case of an oligomer) is preferably 100 to 12,000, more preferably 200 to 10,000, still more preferably 400 to 8,000, still more preferably 600 to 6,000.
The content of the energy ray curable compound in the pressure-sensitive adhesive composition (X) is 100 parts by mass of the total amount of the resin into which the non-energy ray curable acrylic copolymer and the energy ray polymerizable functional group are introduced. On the other hand, it is preferably 30 to 150 parts by mass, more preferably 40 to 90 parts by mass.

The resin having an energy ray polymerizable functional group introduced into the acrylic copolymer contained in the pressure-sensitive adhesive composition (Y) is a resin having a structure derived from the acrylic copolymer as a main chain, Is a resin in which an energy ray-polymerizable functional group is introduced into the side chain of the acrylic copolymer.
Examples of the energy ray polymerizable functional group include a (meth) acryloyl group, a vinyl group, and an aryl group, and a (meth) acryloyl group is preferable.
The method for producing a resin in which an energy ray-polymerizable functional group is introduced into the acrylic copolymer is selected as a copolymer having a functional group by copolymerizing a functional group-containing monomer as the acrylic copolymer. Then, a compound having both a reactive group capable of binding to the functional group and an energy ray polymerizable functional group (hereinafter, also simply referred to as “energy ray polymerizable functional group-introducing compound”) is added to the copolymer. And a method obtained by bonding the functional group of the above and the reactive group.

Moreover, as a reactive group couple | bonded with the said functional group, an isocyanate group, a glycidyl group, etc. are mentioned. Therefore, examples of the energy beam polymerizable functional group-introducing compound include 2-isocyanatoethyl (meth) acrylate and glycidyl (meth) acrylate.
The energy ray polymerizable functional group-introducing compound may be added at 10 to 60 mol% with respect to 100 mol% of the functional group-containing monomer in the acrylic copolymer. preferable. The energy ray-polymerizable functional group-introducing compound is added in an amount of 10 to 60 mol% with respect to the functional group-containing monomer in the acrylic copolymer, thereby securing an appropriate adhesive performance of the adhesive layer, which will be described later. By appropriately crosslinking the acrylic copolymer with a crosslinking agent, it becomes easy to obtain a desired storage elastic modulus. From such a viewpoint, the addition rate of the energy beam polymerizable functional group-introducing compound to 100 mol% of the functional group-containing monomer in the acrylic copolymer is more preferably 30 to 55 mol%, and still more preferably. 35 to 50 mol%.
In addition, you may use this acrylic adhesive for 1 type or in combination of 2 or more types.

(Rubber adhesive)
The rubber-based pressure-sensitive adhesive that can be used in the pressure-sensitive adhesive layer of the present invention is not particularly limited as long as it includes a rubber-based compound and satisfies the above requirement (b). The rubber-based pressure-sensitive adhesive is preferable from the point that adhesive residue hardly occurs when the semiconductor processing pressure-sensitive adhesive sheet is peeled off.
Examples of the rubber compound include natural rubber, modified natural rubber obtained by graft polymerization of one or more monomers selected from (meth) acrylic acid alkyl ester, styrene, and (meth) acrylonitrile on natural rubber, Diene homopolymers such as polybutadiene, polyisoprene, polychloroprene, diene copolymers such as polystyrene-polybutadiene, polystyrene-polyisoprene, styrene-butadiene rubber, acrylonitrile-butadiene rubber, methyl methacrylate-butadiene rubber, urethane rubber, polyisobutylene Resin, polybutene resin and the like. These rubber compounds may be used alone or in combination of two or more.

In addition, as a material containing these rubber compounds, a polyisoprene material can be preferably used. As a commercial item of the polyisoprene material, for example, “Kuraprene” (registered trademark, manufactured by Kuraray Co., Ltd.) can be mentioned. The number average molecular weight (Mn) of the polyisoprene compound contained in the polyisoprene material is preferably 40,000 or less, more preferably 37,000 or less.
In addition, it preferably has a reactive group such as a carboxy group and can be crosslinked with an epoxy compound, an isocyanate compound, an amino compound, or the like, or polymerized by irradiation with energy rays such as a (meth) acryloyl group, particularly ultraviolet rays. It is preferable to use those having a reactive group that can be cross-linked by energy rays. When a material having a reactive group that is polymerized by irradiation with energy rays is used, the rubber-based pressure-sensitive adhesive can be used as an energy ray-curable pressure-sensitive adhesive that is removably cured by irradiation with energy rays. In this case, generation | occurrence | production of the adhesive residue at the time of peeling of the adhesive sheet for semiconductor processing can be suppressed further efficiently. Examples of such a polyisoprene compound include “Claprene LIR-403”, “Claprene LIR-410” (both product names, manufactured by Kuraray Co., Ltd.) having a carboxyl group, and a methacryloyl group and a carboxyl group. “Kuraprene UC-203”, “Kuraprene UC-102” (both are product names, manufactured by Kuraray Co., Ltd.) and the like.
In addition, you may use this rubber adhesive for 1 type or in combination of 2 or more types.
In addition, when using a rubber-type adhesive, you may add a tackifier etc. further.

(Urethane adhesive)
The urethane-based pressure-sensitive adhesive that can be used in the pressure-sensitive adhesive layer of the present invention is a pressure-sensitive adhesive including a urethane-based polymer having at least one of a urethane bond and a urea bond in the main chain and / or side chain, There is no particular limitation as long as it satisfies the requirement (b). A urethane-based pressure-sensitive adhesive is preferable from the point that adhesive residue hardly occurs when the semiconductor processing pressure-sensitive adhesive sheet is peeled off. Examples of commercially available products include urethane adhesives such as “SH-101”, “SH-101M”, “SH-109”, and “SP-205” (product names, manufactured by Toyochem).
The urethane-based pressure-sensitive adhesive can be used as an energy-ray-curable pressure-sensitive adhesive that is cured by irradiation with energy rays and becomes removable. In this case, generation | occurrence | production of the adhesive residue at the time of peeling of the adhesive sheet for semiconductor processing can be suppressed further efficiently. Examples of the pressure-sensitive adhesive composition used for the energy ray-curable pressure-sensitive adhesive include those obtained by blending the energy ray-curable compound blended with the above-described pressure-sensitive adhesive composition (X). When blended with a urethane polymer, energy ray-curable urethane (meth) acrylate or urethane (meth) acrylate oligomer is preferred.
In addition, you may mix | blend the energy-beam curable compound mentioned above with the urethane type adhesives mentioned as an example of said commercial item, and may obtain an energy-beam curable adhesive.
In addition, you may use this urethane type adhesive in combination of 1 type, or 2 or more types.

(Other adhesives)
Furthermore, examples of the pressure-sensitive adhesive that can be used in the pressure-sensitive adhesive layer of the present invention include energy ray-curable pressure-sensitive adhesives other than the above-described energy ray-curable pressure-sensitive adhesive, heat-foaming type, and water-swelling type pressure-sensitive adhesives. It is done.

(Crosslinking agent)
The pressure-sensitive adhesive layer may have a cross-linked structure in which the above acrylic copolymer or polyisoprene material is cross-linked. Examples of the crosslinking agent contained in the pressure-sensitive adhesive composition for crosslinking include an organic polyvalent isocyanate compound, an organic polyvalent epoxy compound, and an organic polyvalent imine compound.
Examples of organic polyvalent isocyanate compounds include aromatic polyvalent isocyanate compounds, aliphatic polyvalent isocyanate compounds, alicyclic polyvalent isocyanate compounds, trimers of these organic polyvalent isocyanate compounds, and these organic polyvalent isocyanate compounds. Examples thereof include terminal isocyanate urethane prepolymers obtained by reacting with a polyol compound.
Further specific examples of the organic polyvalent isocyanate compound include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylene diisocyanate, diphenylmethane-4, 4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3-methyldiphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, tolylene diisocyanate And adducts of trimethylolpropane and the like.

Specific examples of the organic polyvalent epoxy compound include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, Examples thereof include ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.
Specific examples of the organic polyvalent imine compound include N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane-tri-β-aziridinylpropionate, tetra Examples include methylolmethane-tri-β-aziridinylpropionate and N, N′-toluene-2,4-bis (1-aziridinecarboxamide) triethylenemelamine.
The content of the crosslinking agent is preferably 0.01 to 20 parts by weight, more preferably 0.1 to 15 parts by weight, and more preferably 100 parts by weight of a polymer component such as an acrylic copolymer or a polyisoprene material. The ratio is preferably 0.5 to 8 parts by mass. When the content of the cross-linking agent is not more than the above upper limit, the pressure-sensitive adhesive layer is prevented from being excessively cross-linked, and appropriate adhesive force is easily obtained.

(Energy beam polymerization initiator)
Moreover, when using the adhesive composition (X) or adhesive composition (Y) which is an energy ray hardening type as an adhesive composition mentioned above, an energy-beam polymerization initiator (in this specification, " It is preferable to include a photopolymerization initiator ”.
As an energy beam polymerization initiator, the energy beam polymerization initiator mentioned by description of the resin composition for intermediate | middle layers mentioned above is mentioned, for example, You may use 1 type or in combination of 2 or more types.
The amount of the energy beam polymerization initiator is preferably 0.05 to 15 parts by mass, more preferably 0.1 to 10 parts by mass, and still more preferably 0.3 to 100 parts by mass of the total pressure-sensitive adhesive composition. Is 5 parts by mass.

(Other additives)
The above-mentioned pressure-sensitive adhesive composition includes the above-described components such as an antioxidant, a softener (plasticizer), a deterioration inhibitor, an antistatic agent, a flame retardant, a rust inhibitor, a filler, a silicone compound, and a chain transfer agent. Components other than those may be appropriately contained.

<Release material>
The pressure-sensitive adhesive sheet for semiconductor processing of the present invention may further have a release material on the pressure-sensitive adhesive layer.
As the release material, a release sheet that has been subjected to a double-sided release process, a release sheet that has been subjected to a single-sided release process, or the like is used.
Examples of the release material substrate include polyester film such as polyethylene terephthalate resin, polybutylene terephthalate resin, polyethylene naphthalate resin, and plastic film such as polyolefin resin film such as polypropylene resin and polyethylene resin.
Examples of the release agent include rubber elastomers such as silicone resins, olefin resins, isoprene resins, and butadiene resins, long chain alkyl resins, alkyd resins, and fluorine resins.
The thickness of the release material is preferably 5 to 200 μm, more preferably 10 to 120 μm, and still more preferably 15 to 80 μm.

<Method for producing pressure-sensitive adhesive sheet for semiconductor processing>
The method for producing the pressure-sensitive adhesive sheet for semiconductor processing of the present invention is not particularly limited, and can be produced by a known method. Hereinafter, the method for forming the intermediate layer or the pressure-sensitive adhesive layer by coating the intermediate layer resin composition or the pressure-sensitive adhesive composition will be described as an example. Regarding the formation of the intermediate layer, the following method is suitable for obtaining the intermediate layer by casting and curing the curable composition. Moreover, about the formation of an adhesive layer, the method shown below is a method generally used.
As a manufacturing method of the adhesive sheet for semiconductor processing as shown in FIG. 1, for example, a method of forming the intermediate layer 2 on the substrate 3 and then forming the adhesive layer 1 can be mentioned. As a method of forming the intermediate layer 2 on the base material 3, the intermediate layer resin composition solution is directly applied on one surface of the base material 3 to form a coating film, and then a curing treatment is performed. After forming the coating film by directly applying the solution of the resin composition for the intermediate layer to the method of forming the layer 2 or the release treatment surface of the release material, the semi-cured layer is formed on the release material. For example, a method of forming the intermediate layer 2 by completely curing the semi-cured layer before or after removing the release material after the semi-cured layer and the substrate 3 are bonded to each other.
Next, on the intermediate layer 2 produced by the above-described method, the solution of the pressure-sensitive adhesive composition is directly applied and dried to form the pressure-sensitive adhesive layer 1, or the release treatment surface of the release material, A solution of the pressure-sensitive adhesive composition is directly applied and dried to form a pressure-sensitive adhesive layer 1 on the release material. The pressure-sensitive adhesive layer 1 and the intermediate layer 2 created by the above-described method are bonded together, and once for semiconductor processing Examples include a method of manufacturing the pressure-sensitive adhesive sheet 10 and then removing the release material.

When the intermediate layer 2 or the pressure-sensitive adhesive layer 1 is formed, an organic solvent is further added to the resin composition for the intermediate layer or the pressure-sensitive adhesive composition, and the solution of the resin composition for the intermediate layer or the pressure-sensitive adhesive composition It is good also as a form.
Examples of the organic solvent to be used include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, xylene, n-propanol, isopropanol and the like.
In addition, these organic solvents may use the organic solvent used at the time of manufacture of each component contained in the resin composition or adhesive composition for intermediate | middle layers as it is, or 1 or more types of other organic solvents other than that. May be added.
The solid content concentration of the resin composition for the intermediate layer or the pressure-sensitive adhesive composition is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, and still more preferably 15 to 45% by mass.

The intermediate layer resin composition or the pressure-sensitive adhesive composition solution can be applied onto a substrate or a release material by a known application method to form a coating film.
Examples of the coating method include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, die coating, and gravure coating.
In addition, when the solution of the resin composition for the intermediate layer or the pressure-sensitive adhesive composition contains an organic solvent, after applying this, it may be dried by heating at a temperature of 80 to 150 ° C. for 30 seconds to 5 minutes. preferable.

As a curing treatment after applying the intermediate layer resin composition and forming the coating film, a method of irradiating the formed coating film with an energy ray such as ultraviolet rays to polymerize and curing the film is preferable. Moreover, a hardening process may be hardened | cured completely at once, and may be hardened in several steps.
Examples of energy rays include ultraviolet rays and electron beams, and ultraviolet rays are preferable.
Moreover, the irradiation amount of an energy ray is suitably changed according to the kind of energy ray. For example, when ultraviolet rays are used, the illuminance of the irradiated ultraviolet rays is preferably 50 to 500 mW / cm ² , more preferably 100 to 340 mW / cm ² , and the irradiation amount of ultraviolet rays is preferably 100 to 2,500 mJ / cm 2. ² and more preferably 150 to 2,000 mJ / cm ² .
Moreover, you may form the intermediate | middle layer 2 and the adhesive layer 1 by extrusion molding, Such a method is suitable when the intermediate | middle layer 2 and the adhesive layer 1 make an olefin type material the main material. You may obtain the laminated body of the state by which the intermediate | middle layer 2 and the adhesive layer 1 were laminated | stacked by the coextrusion method.

[How to use adhesive sheet for semiconductor processing]
When the adhesive sheet for semiconductor processing of the present invention has a release film, after peeling the release film, the adhesive layer surface of the adhesive sheet for semiconductor processing is stuck on the surface of a semiconductor wafer, particularly the surface of a wafer with bumps. It is used to protect the surface.
Specifically, the bumped wafer to which the semiconductor processing adhesive sheet is attached is polished, but the semiconductor processing adhesive sheet protects the bumped wafer surface in the polishing step, and the bump is crushed. And the occurrence of dimples and cracks on the polished surface can be suppressed. Moreover, the adhesive sheet for semiconductor processing is peeled off from the wafer with bumps when the processing including the polishing step is finished and the surface protection is no longer necessary.
In addition, when affixing the adhesive sheet for semiconductor processing to the wafer with bumps, it is affixed using a laminator or the like, but by using the adhesive sheet for semiconductor processing of the present invention, under pressure and temperature at the time of application By appropriately deforming the intermediate layer and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet for semiconductor processing and following the bumps, a good laminate state can be obtained.
The pressure at the time of sticking the adhesive sheet for semiconductor processing is not particularly limited, but is preferably 0.05 to 1.0 MPa, more preferably 0.1 to 0.5 MPa. The temperature at the time of sticking the adhesive sheet for semiconductor processing is not particularly limited, but is preferably 30 to 100 ° C., more preferably 40 to 80 ° C.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

The measurement method and evaluation method in the present invention are as follows.
[Measuring method]
<Weight average molecular weight (Mw), number average molecular weight (Mn), molecular weight distribution (Mw / Mn)>
The weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw / Mn) of the raw materials used in the following Examples and Comparative Examples are as follows using a gel permeation chromatograph apparatus. The value measured by standard polystyrene conversion was used.
(measuring equipment)
Measuring device: Product name “HLC-8220GPC”, Tosoh column: Two product names “TSKgel GMHXL-L” are connected in series, and one “TSKgel G2000HXL” is connected in this order from the inlet side of the measurement sample. And used. Both detectors manufactured by Tosoh Corporation: differential refractometer (measurement conditions)
Developing solvent: Tetrahydrofuran Column temperature: 40 ° C
Flow rate: 1.0 mL / min

<Loss Tangent (tan δ) and Storage Modulus I of Intermediate Layer>
The UV curable resin composition for forming an intermediate layer used in each of the following Examples and Comparative Examples is a polyethylene terephthalate (PET) film-based release film (product name “SP-PET 381031”, thickness 38 μm, manufactured by Lintec Corporation). A fountain die method was applied to form a coating film. And the ultraviolet-ray was irradiated from the coating-film side, and the semi-hardened layer was formed.
For ultraviolet irradiation, a belt conveyor type ultraviolet irradiation device (product name “ECS-4011GX”, manufactured by Eye Graphics Co., Ltd.) is used as the ultraviolet irradiation device, and a high-pressure mercury lamp (type “H04-L41”, eye (Graphics Co., Ltd.) is used, and the irradiation conditions are as follows: illuminance of 112 mW / cm ^{2 with} a light wavelength of 365 nm, light amount of 177 mJ / cm ² (measured with an ultraviolet light meter “UVPF-A1” manufactured by Eye Graphics) It was.
A polyethylene terephthalate (PET) film release film (product name “SP-PET381031”, thickness 38 μm, manufactured by Lintec Corporation) is laminated on the formed semi-cured layer, and further irradiated with ultraviolet rays (the above-described ultraviolet irradiation device, ultraviolet source). And irradiance of 271 mW / cm ² , light amount of 1,200 mJ / cm ² ) was used and cured completely to form a 200 μm thick intermediate layer with a release film attached to both sides.
Five intermediate layers formed in this way were prepared, and an intermediate layer laminate (thickness: 1,000 μm) was prepared by peeling the PET-based release film and aligning the release surfaces and sequentially laminating them.
Next, the obtained intermediate layer laminate was punched into a circle with a diameter of 10 mm to obtain a sample for measuring viscoelasticity.
Using a viscoelasticity measuring device (product name “ARES”, manufactured by T.A. Instruments Co., Ltd.), the above sample was strained at a frequency of 1 Hz and stored at −50 to 150 ° C. at a temperature rising rate of 4 ° C./min. The elastic modulus (G ′) was measured, and the value of the loss tangent (tan δ) at 50 ° C. and the storage elastic modulus at 50 ° C. were obtained as the storage elastic modulus I.

<Storage elastic modulus A of adhesive layer>
Polyethylene terephthalate (PET) film-based release film (product name “SP-PET 381031”, thickness 38 μm, manufactured by Lintec Corporation) on both sides with a knife coater using the adhesive composition used in each of the following Examples and Comparative Examples A pressure-sensitive adhesive layer having a thickness of 50 μm was formed.
A plurality of pressure-sensitive adhesive layers formed as described above were prepared, and the pressure-sensitive adhesive layer laminate (thickness: 1,000 μm) was prepared by peeling the PET release film and aligning the peeled surfaces together.
Next, the obtained pressure-sensitive adhesive layer laminate was punched into a circle having a diameter of 10 mm to obtain a sample for measuring viscoelasticity.
Using a viscoelasticity measuring device (product name “ARES”, manufactured by T.A. Instruments Co., Ltd.), the above sample was strained at a frequency of 1 Hz and stored at −50 to 150 ° C. at a temperature rising rate of 4 ° C./min. The elastic modulus was measured, and the value of the storage elastic modulus at 50 ° C. was obtained as the storage elastic modulus A.

[Evaluation methods]
<Bump absorbency evaluation>
Adhesive for semiconductor processing produced in the following examples and comparative examples on a wafer with spherical bumps (8-inch wafer, manufactured by Waltz) made of Sn-3Ag-0.5Cu alloy with bump height of 80μm, pitch of 200μm and diameter of 100μm The sheet was attached using a laminator (product name “RAD-3510F / 12”, manufactured by Lintec Corporation). When pasting, the temperature of the laminating table and laminating roll of the apparatus was set to 50 ° C.
After the lamination, the diameter of the circular void generated around the bump from the substrate side was measured using a digital optical microscope (product name “VHX-1000”, manufactured by KEYENCE).
The smaller the gap diameter, the higher the bump absorbability of the semiconductor processing adhesive sheet. Based on the following criteria, the superiority or inferiority of the bump absorbability was determined.
A: The diameter of the void is less than 120 μm.
B: The diameter of the void is 120 μm or more and less than 130 μm.
C: The void diameter is 130 μm or more.

<Evaluation of adhesive residue on bumps>
Adhesive for semiconductor processing produced in the following examples and comparative examples on a wafer with spherical bumps (8-inch wafer, manufactured by Waltz) made of Sn-3Ag-0.5Cu alloy with bump height of 80μm, pitch of 200μm and diameter of 100μm The sheet was attached using a laminator (product name “RAD-3510F / 12”, manufactured by Lintec Corporation). When pasting, the temperature of the laminating table and laminating roll of the apparatus was set to 50 ° C.
After the lamination, UV was irradiated from the pressure-sensitive adhesive sheet for semiconductor processing at an irradiation speed of 15 mm / sec with a UV irradiation apparatus (product name “RAD-2000m / 12”, manufactured by Lintec Corporation). Next, the semiconductor processing pressure-sensitive adhesive sheet was peeled from the evaluation wafer using a wafer mounter (product name “RAD-2700F / 12”, manufactured by Lintec Corporation) under the conditions of a peeling speed of 4 mm / second and a temperature of 40 ° C. Using an electron microscope (product name “VE-9800”, manufactured by KEYENCE Corp.), the portion where the bumps on the adhesive layer surface of the adhesive sheet for semiconductor processing after peeling were embedded was observed from an observation angle of 45 °. Whether the layer was broken or not was confirmed.
The superiority or inferiority of the adhesive residue was determined from the following criteria.
A: No breakage (no adhesive residue).
B: There is a broken part (there is adhesive residue).

[Production Example 1]
<Preparation of substrate A with intermediate layer>
40 parts by mass of monofunctional urethane acrylate, 45 parts by mass of isobornyl acrylate (IBXA) and 15 parts by mass of hydroxypropyl acrylate (HPA), pentaerythritol tetrakis (3-mercaptobutyrate) (product name “Karenz MT PE1” , Secondary tetrafunctional thiol-containing compound (manufactured by Showa Denko KK) 3.5 parts by mass, crosslinking agent 1.8 parts by mass, and 2-hydroxy-2-methyl-1-phenyl as a photopolymerization initiator A UV curable resin composition 1 which was a resin composition for an intermediate layer prepared by blending 1.0 part by mass of -propan-1-one (product name “Darocur 1173”, manufactured by BASF) was obtained.
The UV curable resin composition 1 was applied on a polyethylene terephthalate (PET) release film (product name “SP-PET 381031”, thickness 38 μm, manufactured by Lintec Corporation) by a fountain die method to obtain a coating film.
And the semi-hardened layer which consists of the said UV curable resin composition 1 was formed by irradiating an ultraviolet-ray from the coating-film side.
For ultraviolet irradiation, a belt conveyor type ultraviolet irradiation device (product name “ECS-4011GX”, manufactured by Eye Graphics Co., Ltd.) is used as the ultraviolet irradiation device, and a high-pressure mercury lamp (type “H04-L41”, eye (Graphics Co., Ltd.) is used, and the irradiation conditions are as follows: illuminance of 112 mW / cm ^{2 with} a light wavelength of 365 nm, light amount of 177 mJ / cm ² (measured with an ultraviolet light meter “UVPF-A1” manufactured by Eye Graphics) It was.
On the formed semi-cured layer, a polyethylene terephthalate (PET) film (product name “Cosmo Shine A4100”, thickness 50 μm, manufactured by Toyobo Co., Ltd.) is laminated, and further irradiated with ultraviolet rays from the PET film side (the above ultraviolet irradiation device, Using an ultraviolet light source, the irradiation conditions are irradiance 271 mW / cm ² , light quantity 1,200 mJ / cm ² ), and completely cured to form a substrate A with an intermediate layer having a thickness of 200 μm on the PET film of the substrate. Formed.

[Production Example 2]
<Preparation of base material B with intermediate layer>
40 parts by mass of monofunctional urethane acrylate, 45 parts by mass of isobornyl acrylate (IBXA) and 15 parts by mass of hydroxypropyl acrylate (HPA), pentaerythritol tetrakis (3-mercaptobutyrate) (product name “Karenz MT PE1” 1.5 parts by mass of a secondary tetrafunctional thiol-containing compound (manufactured by Showa Denko KK), and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (product name) as a photopolymerization initiator A UV curable resin composition 2 which was a resin composition for an intermediate layer prepared by blending 1.0 part by mass of “Darocur 1173” (manufactured by BASF) was obtained.
A substrate B with an intermediate layer having a thickness of 200 μm was formed on a PET film as a substrate using the same method as in Production Example 1 except that the UV curable resin composition 2 was used.

[Production Example 3]
<Preparation of substrate C with intermediate layer>
25 parts by mass of a urethane oligomer (Mw: 50,000) composed of polypropylene glycol (PPG, Mw: 4,000) and hexamethylene diisocyanate (HDI), 35 parts by mass of isobornyl acrylate (IBXA), 2- 40 parts by mass of hydroxyphenoxypropyl acrylate (HPPA) and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (product name “Darocur 1173”, manufactured by BASF) as a photopolymerization initiator A UV curable resin composition 3 which was a resin composition for an intermediate layer prepared by blending 0 parts by mass was obtained.
A substrate C with an intermediate layer having a thickness of 200 μm was formed on a PET film as a substrate using the same method as in Production Example 1 except that the UV curable resin composition 3 was used.

[Example 1]
<Preparation of pressure-sensitive adhesive sheet 1 for semiconductor processing>
2-isocyanatoethyl methacrylate (product name “Karenz MOI” (registered trademark)) with respect to an acrylic copolymer comprising 94 parts by mass of 2-ethylhexyl acrylate (2EHA) and 6 parts by mass of 2-hydroxyethyl acrylate (2HEA) , Manufactured by Showa Denko KK) was prepared as a resin solution (adhesive main component, solid content: 35.0% by mass) with an addition rate of 50 mol% to 100 mol% of 2HEA. The weight average molecular weight (Mw) of the obtained resin was 900,000, and Mw / Mn was 9.07.
1.0 part by mass of 1-hydroxylcyclohexyl phenyl ketone (product name “Irgacure 184”, “Irgacure” is a registered trademark, manufactured by BASF)) is added as a photopolymerization initiator to 100 parts by mass of the main component of the adhesive. 0.75 parts by mass of a polyisocyanate compound (product name “BHS-8515”, manufactured by Toyochem Co., Ltd., solid content: 37.5% by mass) was added as an agent, and the mixture was stirred for 30 minutes to prepare an adhesive composition 1. .
Next, the prepared adhesive composition 1 solution was applied to a polyethylene terephthalate (PET) release film (product name “SP-PET 381031”, thickness 38 μm, manufactured by Lintec Corporation) and dried to form an adhesive layer having a thickness of 10 μm. Formed on a release film.
After removing the release film on the substrate A with intermediate layer prepared in advance and pasting the surface of the intermediate layer of the substrate A with intermediate layer and the pressure-sensitive adhesive layer, unnecessary portions at the end in the width direction Was cut and removed to prepare an adhesive sheet 1 for semiconductor processing.

[Example 2]
<Preparation of pressure-sensitive adhesive sheet 2 for semiconductor processing>
A pressure-sensitive adhesive sheet 2 for semiconductor processing was produced using the same method as in Example 1 except that the substrate B with intermediate layer was used.

[Example 3]
<Preparation of pressure-sensitive adhesive sheet 3 for semiconductor processing>
2-isocyanatoethyl methacrylate (product name “Karenz MOI” (registered trademark)) with respect to an acrylic copolymer comprising 90 parts by mass of 2-ethylhexyl acrylate (2EHA) and 10 parts by mass of 4-hydroxybutyl acrylate (4HBA) , Manufactured by Showa Denko KK) was prepared as a resin solution (adhesive main component, solid content: 25% by mass) with an addition rate of 37 mol% with respect to 100 mol% of 4HBA. The weight average molecular weight (Mw) of the obtained resin was 1,000,000, and Mw / Mn was 5.84.
0.75 parts by mass of 1-hydroxylcyclohexyl phenyl ketone (product name “Irgacure 184”, “Irgacure” is a registered trademark, manufactured by BASF)) as a photopolymerization initiator is added to 100 parts by mass of this adhesive main agent, and crosslinked. 0.75 parts by mass of a polyvalent isocyanate compound (product name “BHS-8515”, manufactured by Toyochem Co., Ltd.) was added as an agent, and the mixture was stirred for 30 minutes to prepare an adhesive composition 2.
Subsequently, the adhesive sheet 3 for semiconductor processing was produced using the method similar to Example 1 except using the said adhesive composition 2. FIG.

[Example 4]
<Preparation of pressure-sensitive adhesive sheet 4 for semiconductor processing>
50 parts by mass of toluene was added to 50 parts by mass of a liquid polyisoprene material (product names “Kuraprene UC-203”, “Kuraprene” is a registered trademark, manufactured by Kuraray Co., Ltd.) to prepare Material A having a solid content of 50% by mass.
Further, 50 parts by mass of toluene was added to 50 parts by mass of a liquid polyisoprene material (product names “Kuraprene LIR-410” and “Kuraprene” are registered trademarks, manufactured by Kuraray Co., Ltd.) to prepare a material B having a solid content of 50% by mass. .
100 parts by weight of material A and 50 parts by weight of material B are blended, and 2,2-dimethoxy-1,2-diphenylethane-1-one (product names “Irgacure 651” and “Irgacure” are registered as photopolymerization initiators) (Trademark, manufactured by BASF) is added in an amount of 4.0 parts by mass, and an epoxy compound (product name “TETRAD-C”, “TETRAD” is a registered trademark, manufactured by Mitsubishi Gas Chemical Co., Ltd., 100% solid content) is used as a crosslinking agent. 75 parts by mass was added, and the mixture was stirred for 30 minutes to prepare an adhesive composition 3.
A semiconductor processing pressure-sensitive adhesive sheet 4 was produced in the same manner as in Example 2 except that the pressure-sensitive adhesive composition 3 was used.

[Example 5]
<Preparation of adhesive sheet 5 for semiconductor processing>
100 parts by weight of material A, 100 parts by weight of material B, and 1.25 parts by weight of an epoxy compound (product names “TETRAD-C” and “TETRAD” are registered trademarks, manufactured by Mitsubishi Gas Chemical Company) as a crosslinking agent) Prepared an adhesive composition 4 using the same method as in Example 4.
A semiconductor processing pressure-sensitive adhesive sheet 5 was prepared in the same manner as in Example 4 except that the pressure-sensitive adhesive composition 4 was used.

[Example 6]
<Preparation of adhesive sheet 6 for semiconductor processing>
As urethane-based adhesive “SH-101” (product name, solid content 60% by mass, manufactured by Toyochem) 100 parts by mass, as polyvalent isocyanate component “T-501B” (product name, solid content 75% by mass, "EXL-810TL" (product name, solid content 61% by mass, Dainichi Seisakusho) as polyfunctional urethane acrylate (containing 1-hydroxy-cyclohexyl-phenyl-ketone as a photopolymerization initiator) 43 parts by mass) were added, and the mixture was stirred for 30 minutes to prepare an adhesive composition 5.
A semiconductor processing pressure-sensitive adhesive sheet 6 was produced using the same method as in Example 1 except that the pressure-sensitive adhesive composition 5 was used.

[Example 7]
<Preparation of pressure-sensitive adhesive sheet 7 for semiconductor processing>
2-isocyanatoethyl methacrylate (product name “Karenz MOI” (registered trademark)) with respect to an acrylic copolymer comprising 94 parts by mass of 2-ethylhexyl acrylate (2EHA) and 6 parts by mass of 2-hydroxyethyl acrylate (2HEA) , Manufactured by Showa Denko KK) was prepared as a resin solution (adhesive main component, solid content 58.5% by mass) with an addition rate of 50 mol% with respect to 100 mol% of 2HEA. The weight average molecular weight (Mw) of the obtained resin was 300,000, and Mw / Mn was 3.86.
1.0 part by mass of 1-hydroxylcyclohexyl phenyl ketone (product name “Irgacure 184”, “Irgacure” is a registered trademark, manufactured by BASF)) is added as a photopolymerization initiator to 100 parts by mass of the main component of the adhesive. 0.75 parts by mass of a polyvalent isocyanate compound (product name “BHS-8515”, manufactured by Toyochem Co., Ltd.) was added as an agent, and the mixture was stirred for 30 minutes to prepare an adhesive composition 6.
A semiconductor processing pressure-sensitive adhesive sheet 7 was produced using the same method as in Example 1 except that the pressure-sensitive adhesive composition 6 was used.

[Comparative Example 1]
<Preparation of adhesive sheet 8 for semiconductor processing>
Polyfunctional polybutadiene isocyanate as a crosslinking agent for 100 parts by mass of liquid polybutadiene material (product name “NISSO-PB GQ-2000”, solid content 45% by mass, “NISSO-PB” is a registered trademark, manufactured by Nippon Soda Co., Ltd.) (Product name “NISSO-PB TP-1001”, solid content 50% by mass, manufactured by Nippon Soda Co., Ltd.) was added in an amount of 8.0 parts by mass, and the mixture was stirred for 30 minutes to prepare an adhesive composition 7.
A semiconductor processing pressure-sensitive adhesive sheet 8 was produced in the same manner as in Example 2 except that the pressure-sensitive adhesive composition 7 was used.

[Comparative Example 2]
<Preparation of adhesive sheet 9 for semiconductor processing>
To 30 parts by weight of styrene / ethylene / butylene block copolymer (product name “Tuftec H-1041”, styrene / ethylene / butylene ratio (weight ratio) = 30/70, “Tuftec” is a registered trademark, manufactured by Asahi Kasei Chemicals) 70 parts by weight of toluene was added to prepare an adhesive composition 8 having a solid content of 30% by mass.
A semiconductor processing pressure-sensitive adhesive sheet 9 was prepared in the same manner as in Example 1 except that the pressure-sensitive adhesive composition 8 was used.

[Comparative Example 3]
<Preparation of pressure-sensitive adhesive sheet 10 for semiconductor processing>
70 parts by weight of toluene was added to 30 parts by weight of styrene / ethylene / butylene block copolymer (product name “Tuftec H-1051”, styrene / ethylene / butylene ratio (weight ratio) = 20/80, manufactured by Asahi Kasei Chemicals). Thus, a pressure-sensitive adhesive composition 9 having a solid content of 30% by mass was prepared.
A semiconductor processing pressure-sensitive adhesive sheet 10 was produced using the same method as in Comparative Example 2 except that the pressure-sensitive adhesive composition 9 was used.

[Comparative Example 4]
<Preparation of adhesive sheet 11 for semiconductor processing>
A solution of an acrylic copolymer comprising 59.5 parts by mass of 2-ethylhexyl acrylate (2EHA), 30 parts by mass of vinyl acetate (VAc), 10 parts by mass of 2-hydroxyethyl acrylate (2HEA), and 0.5 parts by mass of acrylic acid. (Adhesive main component, Mw = 720,000, Mw / Mn = 5.98, solid content 40.0% by mass) was prepared.
To 100 parts by mass of the adhesive main component, 6.0 parts by mass of a polyisocyanate compound (product name “BHS-8515”, manufactured by Toyochem Co., Ltd.) is added as a crosslinking agent, and the mixture is stirred for 30 minutes. Composition 10 was prepared.
A semiconductor processing pressure-sensitive adhesive sheet 11 was produced using the same method as in Comparative Example 1 except that the pressure-sensitive adhesive composition 10 was used.

[Comparative Example 5]
<Preparation of pressure-sensitive adhesive sheet 12 for semiconductor processing>
2-isocyanatoethyl methacrylate (product name) is used for an acrylic copolymer consisting of 74 parts by mass of butyl acrylate (BA), 20 parts by mass of methyl methacrylate (MMA) and 6 parts by mass of 2-hydroxyethyl acrylate (2HEA). A solution of a resin (adhesive main component, solid content 35.0% by mass) in which "Karenz MOI" (registered trademark), manufactured by Showa Denko KK) is added so that the addition rate is 80 mol% with respect to 100 mol% of 2HEA Prepared. The weight average molecular weight (Mw) of the obtained resin was 690,000, and Mw / Mn was 6.32.
0.5 parts by mass of a polyvalent isocyanate compound (product name “BHS-8515”, manufactured by Toyochem Co., Ltd.) as a crosslinking agent is added to 100 parts by mass of the adhesive main component, and the mixture is stirred for 30 minutes to produce an adhesive composition. 11 was prepared.
Next, the prepared adhesive composition 11 solution was applied to a polyethylene terephthalate (PET) release film (product name “SP-PET381031,” thickness 38 μm, manufactured by Lintec Corporation) and dried to form a 10 μm thick adhesive layer. Formed on a release film.
After removing the release film on the substrate C with intermediate layer prepared in advance and pasting the exposed intermediate layer surface of the substrate C with intermediate layer and the pressure-sensitive adhesive layer, unnecessary portions at the end in the width direction Was cut and removed to prepare an adhesive sheet 12 for semiconductor processing.

[Comparative Example 6]
<Preparation of pressure-sensitive adhesive sheet 13 for semiconductor processing>
A pressure-sensitive adhesive sheet 13 for semiconductor processing was produced using the same method as in Comparative Example 4 except that the substrate A with intermediate layer was used.

From Table 1, it can be seen that the semiconductor processing pressure-sensitive adhesive sheets 1 to 7 produced in Examples 1 to 7 are excellent in bump absorbability.
On the other hand, the semiconductor processing pressure-sensitive adhesive sheets 8 to 11 and 13 prepared in Comparative Examples 1 to 4 and 6 have a storage elastic modulus A of the pressure-sensitive adhesive layer and a storage elastic modulus I of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz. Since the value of the ratio [A / I] exceeds 1.8, the pressure-sensitive adhesive layer is not deformed enough to follow the bump, and as a result, the bump absorbability is inferior.
Moreover, since the loss tangent of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz is less than 1.0 in the pressure-sensitive adhesive sheet 12 for semiconductor processing produced in Comparative Example 5, the intermediate layer is sufficient for the stress at the time of lamination to the bump wafer. It could not be deformed, and could not follow the bump, resulting in poor bump absorbability.

Since the pressure-sensitive adhesive sheet for semiconductor processing of the present invention is excellent in the absorbability of bumps, generation of voids between the bump and the pressure-sensitive adhesive sheet for semiconductor processing can be particularly prevented.
For this reason, the pressure-sensitive adhesive sheet for semiconductor processing of the present invention is suitable as a surface protective sheet that is attached to a bump of a semiconductor wafer and protects the bump when, for example, grinding a backside of a semiconductor wafer having bumps.

DESCRIPTION OF SYMBOLS 1 Adhesive layer 2 Intermediate layer 3 Base material 10 Adhesive sheet for semiconductor processing

Claims

The adhesive sheet for semiconductor processing which has an intermediate | middle layer and an adhesive layer in this order on a base material, and satisfy | fills following (a) and (b).
(A) The loss tangent of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz is 1.0 or more. (B) The storage elastic modulus A of the pressure-sensitive adhesive layer and the storage elastic modulus of the intermediate layer at 50 ° C. measured at a frequency of 1 Hz. Ratio [A / I] with I is 1.8 or less
2. The semiconductor processing according to claim 1, wherein a ratio [A / I] of the storage elastic modulus A of the pressure-sensitive adhesive layer and the storage elastic modulus I of the intermediate layer at 50 ° C. measured at the frequency of 1 Hz is 1.0 or less. Adhesive sheet.
The pressure-sensitive adhesive sheet for semiconductor processing according to claim 1 or 2, wherein the intermediate layer is formed from a resin composition containing urethane (meth) acrylate and a thiol group-containing compound.
The pressure-sensitive adhesive sheet for semiconductor processing according to any one of claims 1 to 3, wherein the storage elastic modulus I of the intermediate layer at 50 ° C measured at the frequency of 1 Hz is 1.0 × 10 6 Pa or less.
The semiconductor processing pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the intermediate layer has a thickness of 50 to 400 µm.
The semiconductor processing pressure-sensitive adhesive sheet according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive layer is formed of an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, or a urethane-based pressure-sensitive adhesive.
The pressure-sensitive adhesive sheet for semiconductor processing according to claim 6, wherein the acrylic pressure-sensitive adhesive, rubber-based pressure-sensitive adhesive, or urethane-based pressure-sensitive adhesive is an energy ray curable pressure-sensitive adhesive.
The acrylic pressure-sensitive adhesive comprises an acrylic copolymer containing 50 to 98% by mass of an alkyl (meth) acrylate having an alkyl group having 4 or more carbon atoms as a copolymer component based on the total amount of the copolymer component. The adhesive sheet for semiconductor processing of Claim 6 or 7 containing.
The pressure-sensitive adhesive sheet for semiconductor processing according to claim 6 or 7, wherein the acrylic pressure-sensitive adhesive contains a resin having a weight average molecular weight of 800,000 or more obtained by introducing an energy ray-polymerizable functional group into an acrylic copolymer.
A method for protecting the semiconductor processing adhesive sheet according to any one of claims 1 to 9 by attaching it to the surface of a semiconductor wafer.