TW201629174A - Pressure-sensitive adhesive sheet - Google Patents

Abstract

This pressure-sensitive adhesive sheet 10A is a pressure-sensitive adhesive sheet which comprises, disposed in the following order, a base 11, an interlayer 12, and a pressure-sensitive adhesive layer 13, wherein the interlayer 12 is a layer obtained by curing a composition for interlayer formation that comprises a polyfunctional compound having at least two polymerizable functional groups and one or more monofunctional monomers at least including a crystalline monomer having a linear C14-22 carbon chain, the composition for interlayer formation containing the polyfunctional compound in an amount of 25 mass% or larger relative to the monofunctional monomers.

Description

Adhesive film

The present invention relates to an adhesive sheet for attaching an adherend to a semiconductor wafer or the like to protect an adherend, and more particularly to a back-grinding sheet.

In the semiconductor device equipped with such a thinner, more compact, and more versatile information, the semiconductor device is also required to be thinner and higher in density. In order to reduce the thickness of the device, it is required to reduce the thickness of the semiconductor wafer in which the semiconductor is integrated. In order to meet this demand, the back surface of the semiconductor wafer is ground to be thinned.

Further, in recent years, a bump composed of a flux or the like having a height of about 30 to 100 μm is formed on the surface of the wafer, and then the back surface of the semiconductor wafer having the unevenness is ground. When the bump-attached semiconductor wafer is subjected to back grinding, in order to protect the bump portion, an adhesive sheet called a back surface polishing sheet is attached to the surface of the wafer on which the bump has been formed.

The adhesive sheet used for the back surface polishing sheet has an intermediate layer between the substrate and the adhesive layer in order to embed the bump to absorb and relax the height difference of the surface of the semiconductor wafer. Known intermediate layer in order to The embedding property of the bump is good at the bonding temperature, and the retention property of the wafer surface is improved at room temperature, and the form stability when the roll is formed is improved, and the storage elastic modulus is used at a high temperature. An energy ray-hardening resin which is low but becomes high at room temperature.

However, if only the energy ray-curable resin is used alone, the intermediate layer is excessively softened at the bonding temperature, and the intermediate layer is bleed out at the time of attachment, and there is also a possibility that the intermediate layer cannot sufficiently absorb the bumps. Poor situation. In order to solve such a problem, as disclosed in Patent Document 1, an intermediate layer in which a crystallizable hot-melt resin is dispersed in a matrix resin composed of an energy ray-curable resin is also known.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2013-87131

However, when the heat-meltable resin having crystallinity is dispersed in the intermediate layer as in Patent Document 1, the film formation property of the intermediate layer may be lowered. Therefore, even if the hot-melt resin is not used, it is possible to appropriately bury the bumps, sufficiently alleviate the height difference, and prevent the intermediate layer from oozing out at the time of attachment.

The present invention is based on the above problems, the lesson The object of the present invention is to provide an adhesive sheet which can form a bump formed on an adherend when attached to an adherend such as a semiconductor wafer without causing the intermediate layer to contain a crystalline hot-melt resin. Good burying also prevents the oozing of the intermediate layer during attachment.

As a result of careful study of the present invention, it has been found that the above problem can be solved by curing a monofunctional monomer containing a crystalline monomer and a polyfunctional compound having a predetermined ratio or more with respect to the monofunctional monomer to form an intermediate layer. Further, the following invention is completed.

(1) An adhesive sheet comprising, in order, an adhesive sheet of a substrate, an intermediate layer, and an adhesive layer, wherein the intermediate layer is used to harden an intermediate layer containing a polyfunctional compound and a monofunctional monomer. In general, the polyfunctional compound is a compound having at least two polymerizable functional groups, and the monofunctional monomer is a crystalline monomer having at least a carbon chain having a linear carbon number of 14 to 22, and the intermediate layer is used. The composition contained more than 25% by mass of the above polyfunctional compound.

(2) The adhesive sheet according to the above (1), wherein 40% by mass or more of the monofunctional monomer is the crystalline monomer.

(3) The adhesive sheet according to (1) or (2) above, wherein the polyfunctional compound is a polyfunctional oligomer having a weight average molecular weight of 3,000 to 60,000.

(4) The adhesive sheet according to any one of (1) to (3) above wherein the polymerizable functional group of the polyfunctional compound is a group having an ethylenic double bond.

(5) The adhesive sheet according to any one of (1) to (4) above, wherein the aforementioned plurality of officials The energy compound is at least one selected from the group consisting of urethane (meth) acrylate oligomers, acrylic polymers, and butadiene polymers.

(6) The adhesive sheet according to any one of the above (1) to (5), wherein the crystalline monomer is contained in an amount of 25 to 70% by mass based on the total amount of the intermediate layer composition.

(7) The adhesive sheet according to any one of (1) to (6) above wherein the composition for the intermediate layer is an energy ray-curable type.

(8) The adhesive sheet according to any one of the above (1), wherein the intermediate layer has a thickness of 150 to 700 μm.

(9) The adhesive sheet according to any one of the above (1) to (8), which is a tape for protecting a semiconductor wafer.

According to the present invention, it is possible to provide an adhesive sheet which can improve the burying property of the unevenness of the adherend when the adhesive sheet is attached to an adherend such as a semiconductor wafer, and can prevent the bleed out of the intermediate layer at the time of attachment. .

10A, 10B‧‧‧Adhesive tablets

11‧‧‧Substrate

12‧‧‧Intermediate

13‧‧‧Adhesive layer

14‧‧‧ peeling material

Fig. 1 is a cross-sectional view showing an adhesive sheet according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing an adhesive sheet according to another embodiment of the present invention.

Hereinafter, the present invention will be described using an embodiment. Further, in the following description, the "weight average molecular weight (Mw)" is a value measured by a gel permeation chromatography (GPC) method in terms of polystyrene, specifically, measured according to the method described in the examples. value.

Further, in the description of the present specification, for example, "(meth)acrylate" is used as a term for both "acrylate" and "methacrylate", and the same applies to the other similar terms.

1 and 2 show an adhesive sheet according to an embodiment of the present invention. The adhesive sheet of the present invention is similar to the adhesive sheet 10A shown in Fig. 1, and is not particularly limited as long as the intermediate layer 12 is provided on the substrate 11, and the adhesive layer 13 is further provided on the intermediate layer 12. The adhesive sheet can be composed of three layers, and other layers can be provided. For example, as in the adhesive sheet 10B shown in FIG. 2, the release material 14 may be further provided on the adhesive layer 13.

Hereinafter, each member constituting the adhesive sheet will be described in more detail.

[middle layer]

The intermediate layer is formed by curing a polyfunctional compound having at least two polymerizable functional groups with an intermediate layer of a monofunctional monomer containing at least a crystalline monomer having a linear carbon number of 14 to 22; Adult.

In the present invention, since the intermediate layer forming intermediate layer contains a polyfunctional compound and a monofunctional monomer, and at least a part of the monofunctional monomer is a crystalline monomer, the adhesive sheet can be used for the bump of the semiconductor wafer. The burying property of the unevenness of the surface of the adherend becomes good. Also, it can become high When the adhesive sheet is attached to an adherend such as a semiconductor wafer under temperature, the interlayer is prevented from seeping out.

The intermediate layer composition is cured by polymerizing a polyfunctional compound and a monofunctional monomer to form an intermediate layer. The intermediate layer composition is preferably an energy ray-hardening type which is hardened by an energy ray. Further, the energy line means an energy quantum having an electromagnetic wave or a charged particle beam, and although it is an active light or an electron beam such as ultraviolet light, it is preferable to use ultraviolet light.

<multifunctional compound>

In the composition for an intermediate layer, the polyfunctional compound is contained in an amount of more than 25% by mass based on the total amount of the monofunctional monomer. When the content of the polyfunctional compound is 25% by mass or less, it becomes difficult to ensure the burying property. Further, the content of the polyfunctional compound is preferably 30% by mass or more, and more preferably 50% by mass or more. When the content is 30% by mass or more, the burying property is more likely to be improved. Further, in order to secure a certain content of the monofunctional monomer, the upper limit of the content is preferably 250% by mass or less, preferably 200% by mass or less.

Further, the polymerizable functional group contained in the polyfunctional compound is preferably a group having an ethylenic double bond. By having an ethylenic double bond, the polyfunctional compound can be hardened by an energy ray such as ultraviolet rays. Here, specific examples of the group having an ethylenic double bond include a (meth)acryl fluorenyl group and a vinyl group, and a (meth) acrylonitrile group is preferred.

The polyfunctional compound may be any of a polyfunctional monomer and a polyfunctional oligomer, but the polyfunctional oligomer is intercalated with the crystalline monomer during hardening. The use will be more enhanced, so it is preferred to use a polyfunctional oligomer. The polyfunctional compound may be used alone or in combination of two or more. When two or more kinds of polyfunctional compounds are used, either of two kinds of polyfunctional monomers and polyfunctional oligomers may be used, and both polyfunctional monomers and polyfunctional oligomers may be used.

(polyfunctional oligomer)

The weight average molecular weight of the polyfunctional oligomer is preferably from 3,000 to 60,000, more preferably from 5,000 to 50,000. By setting the weight average molecular weight to the above range, the burying property of the intermediate layer can be improved, and the bleeding of the intermediate layer can be easily prevented. Further, the polyfunctional oligomer is formed into a liquid form, and the viscosity thereof is in an appropriate range, and the film formability is easily improved.

Specific examples of the polyfunctional oligomer which can be used for the intermediate layer include, for example, a urethane (meth) acrylate oligomer, an acrylic polymer, a butadiene polymer, and polyisoprene. Alkene and the like. Among these, a urethane (meth) acrylate oligomer, an acrylic polymer, and a butadiene-based polymer are preferred. Further, as the oligomer, although a monofunctional oligomer having a single polymerizable functional group is also known, in the present invention, if a polyfunctional oligomer is substituted and a monofunctional oligomer is used, the temperature is high. The lower intermediate layer is excessively softened, and it becomes difficult to prevent the bleeding of the intermediate layer.

Hereinafter, a urethane (meth) acrylate oligomer, an acrylic polymer, and a butadiene polymer which can be used for a polyfunctional oligomer will be specifically described.

"Carbamate (meth) acrylate oligomer"

The urethane (meth) acrylate oligomer is a compound having at least a (meth) acrylonitrile group and a urethane bond, and has a property of being polymerized by irradiation with an energy ray.

The number of (meth) acrylonitrile groups (i.e., polymerizable functional groups) in the urethane (meth) acrylate oligomer may be two or more, but preferably two. A urethane (meth) acrylate oligomer is, for example, a reaction of a polyol compound with a polyvalent isocyanate compound to obtain a terminal isocyanate urethane prepolymer, and a (meth)acrylic acid having a hydroxyl group. It can be obtained by ester reaction.

Further, the urethane (meth) acrylate oligomers may be used singly or in combination of two or more.

a. polyol compound

The polyol compound is a compound having two or more hydroxyl groups, and examples of the specific polyol compound include polyether polyols, polyester polyols, and polycarbonate polyols. Ether polyols are preferred. Further, the polyol compound may be any of a bifunctional diol, a trifunctional triol, and a tetrafunctional or higher polyhydric alcohol, but a bifunctional diol is preferred.

For example, the polyether polyol is preferably a compound represented by the following formula (1).

In the above formula (1), R is a divalent hydrocarbon group, preferably an alkyl group, and carbon The alkylene group having 1 to 6 is preferred. Among the alkylene groups having 1 to 6 carbon atoms, an ethyl group, a propyl group and a tetramethylene group are preferred, and a propyl group and a tetramethylene group are preferred.

Further, n is the number of repeating units of the alkylene oxide, and is usually 10 to 250, preferably 25 to 205, more preferably 40 to 185. When n is in the above range, the urethane bond concentration of the obtained urethane (meth) acrylate oligomer is made moderate, and the flexibility of the intermediate layer is easily improved.

Among the compounds represented by the above formula (1), polyethylene glycol, polypropylene glycol, and polytetramethylene glycol are preferred, and polypropylene glycol and polytetramethylene glycol are preferred.

The polyester polyol is obtained by polycondensation of a polyol component and a polybasic acid component. Examples of the polyol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 1,3-butylene glycol, and 1,4-butanediol. , neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, hexanediol, octanediol, 2 , 2-Diethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,4-cyclohexanedimethanol, ethylene glycol or propylene glycol addition of bisphenol A Various glycols and the like are known as materials and the like.

As the polybasic acid component used for producing the polyester polyol, a compound known as a polybasic acid component of a polyester can be generally used.

Specific examples of the polybasic acid component include adipic acid, maleic acid, succinic acid, oxalic acid, fumaric acid, malonic acid, glutaric acid, pimelic acid, sebacic acid, sebacic acid, and octane. An aliphatic dibasic acid such as diacid; a dibasic acid such as capric acid, isodecanoic acid, p-citric acid or 2,6-naphthalenedicarboxylic acid, or trimellitic acid, An aromatic polybasic acid such as polybasic acid such as pyromellinic acid corresponds to an anhydrate or a derivative thereof, a dimer acid, a hydrogenated dimer acid, or the like.

The polycarbonate polyol is not particularly limited, and examples thereof include a polyalkylene carbonate diol. The polyalkylene carbonate diol may, for example, be a polytetramethylene carbonate diol, a polypentamethylene carbonate diol, a polyhexamethylene carbonate diol, or have a tetramethylene group. A linear alkyl group having a carbon number of 4 to 8 is exemplified as a repeating unit exemplified by a copolymer of two or more kinds of mixed alkylene groups selected from the group consisting of pentamethylene and hexamethylene.

b. Polyvalent isocyanate compound

Examples of the polyvalent isocyanate compound include aliphatic polyisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate; and isophorone diisocyanate; An alicyclic group such as norbornane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, dicyclohexylmethane-2,4'-diisocyanate, ω,ω'-diisocyanate dimethylcyclohexane Diisocyanates; 4,4'-diphenylmethane diisocyanate, methylphenyl diisocyanate, decyl diisocyanate, tolidine diisocyanate, tetramethylene decyl diisocyanate, naphthalene-1, An aromatic diisocyanate such as 5-diisocyanate.

From the viewpoint of workability, isophorone diisocyanate, hexamethylene diisocyanate, and mercapto diisocyanate are preferred among these.

c. (meth) acrylate having a hydroxyl group

The above polyol compound is reacted with a polyvalent isocyanate compound to obtain The terminal isocyanate urethane prepolymer is reacted with a (meth) acrylate having a hydroxyl group to obtain a urethane (meth) acrylate oligomer.

The (meth) acrylate having a hydroxyl group is not particularly limited as long as it is a compound having at least a hydroxyl group and a (meth) acrylonitrile group in one molecule.

Specific examples of the (meth) acrylate having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxy butyl (methyl). Acrylate, 4-hydroxycyclohexyl (meth) acrylate, 5-hydroxycyclooctyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, pentaerythritol III ( a hydroxyalkyl (meth) acrylate such as methyl acrylate, polyethylene glycol mono (meth) acrylate or polypropylene glycol mono (meth) acrylate; N-hydroxymethyl (meth) acrylonitrile The hydroxyl group such as an amine contains (meth) acrylamide, vinyl alcohol, vinyl phenol, a reaction product obtained by reacting a diglycidyl bisphenol A with (meth)acrylic acid, and the like.

Among these, hydroxyalkyl (meth) acrylate is preferred, and 2-hydroxyethyl (meth) acrylate is preferred.

Acrylic Polymer

The acrylic polymer to be used as the polyfunctional compound is preferably one obtained by polymerizing a (meth) acrylate, and polymerizing the alkyl group to have a carbon number of from 1 to 10, preferably. It is obtained by polymerizing an alkyl (meth) acrylate having an alkyl group having 3 to 8 carbon atoms.

Here, the alkyl group in the alkyl (meth) acrylate may be branched or linear. As the alkyl (meth) acrylate, for example, methyl (methyl) propyl Ethyl ester, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (A) Acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like. The acrylic polymer has a polymerizable functional group at both terminals, and the polymerizable functional group is usually a (meth) acrylonitrile group.

Butadiene Polymer

Examples of the butadiene-based polymer include those having two or more vinyl groups in a side chain. The vinyl group in the side chain of the butadiene-based polymer is a polymerizable functional group, and is capable of reacting with a monofunctional monomer to be cured. The butadiene-based polymer is obtained by polymerizing butadiene as a monomer unit, and usually includes a 1,4 bond unit and a 1,2 ethylene bond unit.

(multifunctional monomer)

Further, a polyfunctional monomer which is the above polyfunctional compound can be used, and examples thereof include a (meth)acrylic polyfunctional monomer, and a specific example of a (meth)acrylic polyfunctional monomer such as pentaerythritol tris(methyl) Acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane tetra(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, Ethylene oxide is added with glycerin (meth) acrylate, dipropylene glycol di (meth) acrylate, or the like.

<monofunctional monomer>

(crystalline monomer)

The monofunctional monomer is a monomer having one ethylenic double bond. The monofunctional monomer contained in the composition for an intermediate layer contains at least a crystalline monomer. When the crystalline monomer is a carbon chain having a linear carbon number of 14 to 22, when the intermediate layer is polymerized by a curing reaction, crystallinity is imparted to the side chain of the obtained polymer. In the present invention, since the composition for the intermediate layer contains the crystalline monomer, the elastic modulus of the intermediate layer is lowered and deformed when it is attached by heating, and the burying property is easily improved. Further, the crystalline single system refers to a monomer having an ethylenic double bond and having a linear carbon number of 14 to 22 and having a crystallinity in a side chain when the polymer is produced.

It is preferable that 40% by mass or more of the monofunctional monomer contained in the composition for the intermediate layer is a crystalline monomer. In the present invention, when the crystalline monomer is 40% by mass or more, the elastic modulus is further improved at the time of heat application, and the delamination of the intermediate layer when the adhesive sheet is attached can be prevented, and the burying property can be improved.

Further, among the monofunctional monomers, a crystalline monomer is preferably 45 to 100% by mass, and a crystalline monomer is preferably 77 to 100% by mass. In this way, when the content of the crystalline monomer in the monofunctional monomer is increased, the decrease in the elastic modulus of the intermediate layer at the time of heat application becomes remarkable, so that it is possible to exhibit better burying properties and at the same time suppress storage. The resin from the middle layer of the adhesive sheet oozes out.

The crystalline monomer is one having one ethylenic double bond, and specifically, a (meth)acryl fluorenyl group or a vinyl group is preferred, and a (meth) acrylonitrile group is preferred. Crystalline monomer due to ethylene Since it is a double bond, it becomes easy to polymerize by irradiation of an energy ray. Further, by having a (meth) acrylonitrile group, the hardening reaction proceeds easily.

The crystalline single system preferably has a linear alkyl group having 14 to 22 carbon atoms. By the linear alkyl group having such a long carbon chain, the crystalline monomer can impart crystals to the side chain of the polymer obtained by curing the intermediate layer composition. Further, the carbon number of the linear alkyl group is preferably from 16 to 20.

Specific examples of the crystalline monomer include an alkyl (meth) acrylate having a linear alkyl group having 14 to 22 carbon atoms, an alkyl vinyl group having a linear alkyl group having 14 to 22 carbon atoms, and the like. However, an alkyl (meth) acrylate having a linear alkyl group having 14 to 22 carbon atoms is preferred. By using an alkyl (meth) acrylate, it becomes easy to carry out a hardening reaction favorable.

Examples of the alkyl (meth) acrylate having a linear alkyl group having 14 to 22 carbon atoms include, for example, myristyl (meth) acrylate, palmityl (meth) acrylate, and stearin. (meth) acrylate, arrachinyl (meth) acrylate, and behenyl (meth) acrylate, but from the viewpoint of easiness of availability, etc., among these, stearyl methacrylate (meth) acrylate Esters are preferred.

Further, examples of the alkylvinyl group having a linear alkyl group having 14 to 22 carbon atoms include a myristyl vinyl group, a palmityl vinyl group, a stearyl vinyl group, an arrachinyl vinyl group, and a 22nd base group. Vinyl and the like.

Further, the total amount of the composition for the intermediate layer is preferably from 25 to 70% by mass based on the total amount of the crystalline monomer, and preferably from 40 to 60% by mass. When the content is 25% by mass or more, the portion having crystallinity in the intermediate layer is increased, and the elastic modulus of the intermediate layer at the time of high temperature is lowered, and the burying property is more easily improved. In addition, if it is 70% by mass or less, it becomes It is easy to ensure the softness necessary as an intermediate layer.

(other monofunctional monomers)

The monofunctional monomer contained in the composition for an intermediate layer may be composed only of the above crystalline monomer, and may contain a monofunctional monomer other than the crystalline monomer.

The monofunctional monomer other than the crystalline monomer is a group having an ethylenic double bond such as a (meth) acrylonitrile group or a vinyl group, and specifically, a (meth) acrylate having an alicyclic structure is exemplified. An ester, a (meth) acrylate containing a functional group, an alkyl (meth) acrylate having an alkyl group of less than 14 carbon atoms, a guanamine containing compound, a (meth) acrylate having an aromatic structure, and having a (meth) acrylate having a heterocyclic structure, another vinyl compound, or the like, wherein at least a (meth) acrylate having an alicyclic structure and a functional group-containing (meth) acrylate are used. Any one is better.

Examples of the (meth) acrylate having an alicyclic structure include isodecyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentyl (meth) acrylate. , dicyclopentenyloxy (meth) acrylate, cyclohexyl (meth) acrylate, adamantane (meth) acrylate, etc., among which isodecyl (meth) acrylate is used good.

The functional group used for the functional group-containing (meth) acrylate may, for example, be a hydroxyl group, an amine group or an epoxy group. Specific examples of the functional group-containing (meth) acrylate include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxypropyl (A). Acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxy a hydroxyl group-containing (meth) acrylate such as a propyl (meth) acrylate; a (meth) acrylate containing a first amine group; a (meth) acrylate containing a second amine group, Amino group-containing (meth) acrylate such as a third amino group (meth) acrylate; epoxypropyl (meth) acrylate, methyl epoxy propyl (meth) acrylate, olefin An epoxy group-containing (meth) acrylate or the like such as propylepoxypropyl ether. Among these, a hydroxyl group-containing (meth) acrylate is preferred, and 2-hydroxy-3-phenoxypropyl (meth) acrylate is preferred.

Examples of the alkyl (meth) acrylate having an alkyl group having less than 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, and n-propyl (meth) acrylate. Ester, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (a Acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, n-fluorenyl (meth) acrylate, n - mercapto (meth) acrylate and the like.

Examples of the guanamine-containing compound include (meth) acrylamide, N,N-dimethyl(meth) acrylamide, N-butyl(meth) acrylamide, and N-hydroxyl. Methyl (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (methyl) A (meth) acrylamide compound such as acrylamide.

Examples of the (meth) acrylate having an aromatic structure include benzyl (meth) acrylate and the like. Examples of the (meth) acrylate having a heterocyclic structure include tetrahydroindenyl (meth) acrylate, morpholine acrylate, and the like. Further, examples of the other vinyl compound include styrene, hydroxyethylvinyl, hydroxybutylvinyl, N-vinylformamide, and N-. Vinyl pyrrolidone, N-vinyl caprolactam, and the like.

<Photopolymerization initiator>

The composition for the intermediate layer preferably contains a photopolymerization initiator and is easily hardened when exposed to active light such as ultraviolet rays.

The photopolymerization initiator may, for example, be a photopolymerization initiator such as a benzoin compound, an acetophenone compound, a mercaptophosphine oxide compound, a titanocene compound, a thioxanthone compound or a peroxide compound. Specific examples thereof include 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, benzoin, benzoin methyl ether, benzoin ethyl ether, and benzoin Propyl ether, 2,4,6-trimethylbenzylidene-diphenyl-phosphine oxide, and the like. Further, depending on the type of the polyfunctional compound or the monofunctional monomer, in addition to the above, an aromatic diazonium salt, an aromatic halosulfonium salt, an aromatic onium salt, a nitrobenzyl ester, a sulfonic acid derivative can be used. Anionic photopolymerization initiator for cationic, photopolymerization initiators such as phosphoric acid esters and sulfonic acid derivatives, and a catalyst system of titanium alkoxide and p-chlorophenyl-o-nitrobenzyl ether . The photopolymerization initiator can be used singly or in combination of two or more.

The content of the photopolymerization initiator is preferably 0.05 to 15 parts by mass, preferably 0.1 to 10 parts by mass, more preferably 0.3 to 5 parts by mass based on 100 parts by mass of the total of the above polyfunctional compound and monofunctional monomer. Share. Further, the composition for the intermediate layer may contain a light sensitizer containing an amine or a ruthenium or the like.

The composition for the intermediate layer may contain other additives insofar as it does not impair the effects of the present invention. Examples of other additives include antioxidants, antistatic agents, softeners (plasticizers), fillers, and rust preventive agents. Agents, pigments, dyes, etc.

Further, the composition for the intermediate layer preferably contains no heat-fusible resin. When the composition for an intermediate layer of the present invention contains a crystalline monomer component, even if it does not substantially contain a hot-melt resin, it is possible to prevent bleed out of the intermediate layer at the time of attachment, and it is possible to improve the burying property. Further, the hot-melt resin means a clear and sharp melting peak observed under DSC measurement, specifically, the difference between the melting start temperature and the melting peak temperature (melting point (Tm)) is below 8 ° C, for example, melting point ( Tm) is 45~90 °C. Examples of the hot-melt resin include an acrylic polymer which is waxy at room temperature, a polymer of α-olefin having 14 to 30 carbon atoms, and the like.

Further, the fact that the heat-fusible resin is not substantially contained means that the composition for the intermediate layer may contain a heat-meltable resin to the extent that it does not affect the film formability of the intermediate layer, and for example, means a composition with respect to the intermediate layer. The total amount may be less than 2% by mass, and the content thereof is preferably less than 1% by mass, and preferably not contained. By substantially not containing the hot-melt resin, it is possible to suppress aggregation or increase in viscosity due to the solid polymer material in the intermediate layer composition.

In the composition for the intermediate layer, the polyfunctional compound and the monofunctional monomer are usually used as the main component, and the total amount of the composition is usually 70% by mass or more and 80% by mass or more based on the total amount of the composition for the intermediate layer. Preferably, it is preferably 90% by mass or more. In addition, as long as the total amount of the components for the intermediate layer is 100% by mass or less, it is preferably 99.9% by mass or less, preferably 99.7 by mass, in order to mix the additive such as a photopolymerization initiator. % below. Moreover, the total amount of components used in the intermediate layer refers to When the composition is diluted by a solvent or the like which volatilizes during the production, the amount of the volatile component such as the dilution solvent is removed.

The thickness of the intermediate layer is suitably adjusted depending on the height of the bump or the like to be protected, and is preferably 150 to 700 μm, preferably 200 to 300 μm. When the thickness of the intermediate layer is 150 μm or more, even if the bump is high and the adherend such as a wafer having a large height difference is adhered, it can be appropriately protected. Further, if the thickness is 700 μm or less, the deformation of the adhesive sheet during bending can be reduced.

[substrate]

The substrate to be used for the adhesive sheet is not particularly limited, but a resin film is preferred. Since the resin film generates less dust than paper or non-woven fabric, it is suitable for a processed member of an electronic component, and since it is easy to obtain, a resin film is preferable. The substrate may be a single layer film composed of a single resin film, or a multilayer film formed by laminating a plurality of resin films.

The resin film used as the base material may, for example, be a polyolefin film, a halogenated vinyl polymer film, an acrylic resin film, a rubber film, a cellulose film, a polyester film, or a polycarbonate system. A film, a polystyrene film, a polyphenylene sulfide film, a cycloolefin polymer film, or the like.

From the viewpoint of being able to stably maintain the wafer when the wafer is extremely thin, and from the viewpoint of a film having high thickness precision, a polyester film is preferable among these, and the polyester film is easily obtained. From the viewpoint of high thickness precision, a polyethylene terephthalate film is also preferred.

Further, the thickness of the substrate is not particularly limited, and is preferably 10 to 250 μm. It is preferably 20 to 200 μm.

Further, from the viewpoint of improving the adhesion between the substrate and the intermediate layer, a substrate having an easy adhesion layer or the like laminated on the surface of the resin film may be used. Further, the substrate may contain a filler, a colorant, an antistatic agent, an antioxidant, an organic slip agent, a catalyst, or the like, without impairing the effects of the present invention.

The substrate may be transparent or opaque. However, when the adhesive or the composition for the intermediate layer constituting the adhesive layer is an energy ray-curable type, the substrate is preferably an energy ray penetrable.

[Adhesive layer]

Examples of the adhesive for forming the pressure-sensitive adhesive layer include an acrylic adhesive, a rubber adhesive, a polyoxygen adhesive, a polyvinyl ether adhesive, and a urethane adhesive. The middle system is preferably an acrylic adhesive. In addition, examples of the adhesive include an energy ray-curable type, an energy-line foaming type adhesive, a heat-foaming type, and a water-swellable type, and among these, energy such as an ultraviolet curing type or an electron beam curing type is used. A wire hardening type adhesive is preferred, and an ultraviolet curing type adhesive is preferred.

By using an energy ray-curable adhesive, the adhesive sheet can be surely adhered to the semiconductor wafer before the irradiation of the energy ray, and the adherend such as the semiconductor wafer can be surely protected. On the other hand, when the adhesive sheet is peeled off, the energy ray is irradiated, so that the adhesive force of the adhesive layer can be lowered, so that the adhesive of the semiconductor wafer or the like can be prevented from being damaged, and the adhesive remains without being adhered to the adherend. The piece is peeled off from the adhesive.

The energy ray-curing type adhesive may be an additive type energy ray-curable adhesive containing a matrix polymer such as an acrylic copolymer and an energy ray-curable resin, but may be used in a polymer side chain or a main chain or A so-called intrinsic energy ray-curable adhesive having a polymer having a radical-reactive carbon-carbon double bond at the end of the main chain as a matrix polymer such as an acrylic copolymer.

Further, the adhesive is a matrix polymer containing an acrylic copolymer or the like, and a crosslinking agent, a photopolymerization initiator, and the like are also required as necessary.

The thickness of the adhesive layer is adjusted in accordance with the height difference of the surface of the adherend such as a semiconductor wafer or the performance required for the adhesive sheet, and is usually 3 to 200 μm, preferably 7 to 150 μm, preferably 10 to 100 μm. .

[release material]

The release material used for the adhesive sheet or the release material used in the step of the production method described later is a release sheet which has been subjected to the one-side peeling treatment, or a release sheet which has been subjected to the double-side peeling treatment, and the like, and may be used as a base for the release material. A stripper is applied to the material.

The base material for a release material may, for example, be a polyester resin film such as polyethylene terephthalate resin, polybutylene terephthalate resin or polyethylene naphthalate resin, polypropylene resin, or poly A plastic film or the like such as a polyolefin resin film such as a vinyl resin.

Examples of the release agent include a rubber-based elastomer such as a polyfluorene-based resin, an olefin-based resin, an isoprene-based resin, and a butadiene-based resin, a long-chain alkyl-based resin, and an alkyd-based resin. Fluorine resin or the like.

Further, the thickness of the release material is not particularly limited, and is preferably 5 to 200 μm, more preferably 10 to 120 μm.

[Method of manufacturing adhesive sheet]

The method for producing the adhesive sheet of the present invention is not particularly limited, and the adhesive sheet can be produced by a known method.

For example, the intermediate layer can be formed by directly applying a coating film for forming an intermediate layer on one surface of a substrate and then performing a curing treatment. Further, the intermediate layer is formed by directly applying a composition for an intermediate layer to the release-treated surface of the release material, and performing a curing treatment, or by bonding a substrate to the coating film. In this case, the release material may be suitably peeled off, for example, after completion of the curing treatment. Further, the hardening of the intermediate layer is preferably carried out by irradiating the formed coating film with an energy ray such as ultraviolet rays. In this case, the amount of irradiation of the energy ray is appropriately changed depending on the type of the energy ray, the thickness of the coating film, and the like. For example, in the case of using ultraviolet rays, the ultraviolet illuminance to be irradiated is preferably 50 to 500 mW/cm ² . Further, the amount of ultraviolet light is preferably from 100 to 2,500 mJ/cm ² .

Further, the adhesive layer is formed by, for example, directly applying an adhesive composition to the intermediate layer formed as described above and drying it. Further, the adhesive composition may be applied to the release-treated surface of the release material, dried to form an adhesive layer on the release material, and then the adhesive layer and the intermediate layer on the release material may be bonded to each other. An adhesive sheet provided with an intermediate layer, an adhesive layer, and a release material is formed on the substrate. Thereafter, the release material in the adhesive sheet may be peeled off as necessary.

When the intermediate layer or the adhesive layer is formed, the intermediate layer composition or the adhesive composition may be further blended with an organic solvent to form a diluent for the intermediate layer composition or the adhesive composition.

The organic solvent to be used may, for example, be methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexane, n-hexane, toluene, hydrazine, n-propanol or isopropanol. Wait.

In addition, as the organic solvent, the organic solvent used in the synthesis of the components contained in the intermediate layer composition or the adhesive composition may be used as it is, or one or more organic solvents other than the organic solvent may be added.

The composition for the intermediate layer or the composition of the adhesive can be applied by a known coating method. Examples of the coating method include spin coating, spray coating, bar coating, knife coating, roll coating, blade coating, and die coating. Gravure coating method, etc.

Further, when the composition for the intermediate layer or the composition of the adhesive is a compound containing an organic solvent, it is preferred to apply a drying treatment after heating.

[How to use the adhesive sheet]

The adhesive sheet of the present invention can be used in various applications, but it is preferably used as a semiconductor wafer protective tape for attaching to a semiconductor wafer. Further, it is preferable that the adhesive sheet is used as a back surface polishing tape, and the back surface polishing tape is attached to the surface of the semiconductor wafer, and the circuit formed on the surface of the wafer is protected when the back surface of the wafer is ground.

The adhesive sheet of the present invention is high even when it is on the surface of the wafer due to bumps or the like. When the difference is low, since the burying property is good, the protection performance of the wafer surface becomes good. Further, when the adhesive sheet is attached to the wafer, the adhesive sheet is heated, and even if it is attached by heating, no bleeding of the intermediate layer occurs.

Further, the height of the bump formed on the surface of the wafer is not particularly limited, and the burying property of various height bumps can be improved by appropriately selecting the thickness of the intermediate layer or the adhesive layer of the adhesive sheet of the present invention. .

Further, the temperature of the adhesive sheet when the adhesive sheet is attached to the semiconductor wafer is, for example, about 40 to 80 ° C, preferably 50 to 60 ° C.

Moreover, the adhesive sheet is not limited to the back abrasive sheet and can be used for other purposes. For example, an adhesive sheet can also be used as a dicing sheet that is attached to the back side of the wafer to protect the back side of the wafer when the wafer is diced.

[Examples]

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

The measurement method and evaluation method in the present invention are as follows.

[Weight average molecular weight (Mw)]

The gel permeation chromatography apparatus (product name "HLC-8020", manufactured by Tosoh Corporation) was used, and the measurement was performed under the following conditions, and the values measured in terms of standard polystyrene were used.

(measurement conditions)

Pipe column: "TSK guard column HXL-H" "TSK gel GMHXL (×2)" "TSK gel G2000HXL" (all manufactured by Tosoh Corporation)

Column temperature: 40 ° C Development solvent: tetrahydrofuran Flow rate: 1.0 mL / min

[burial evaluation]

After the release sheets of the adhesive sheets prepared in the examples and the comparative examples were peeled off, the adhesive sheets were attached to a height of 80 μm, a pitch of 200 μm, and a diameter of 100 μm using a laminator RAD-3510F/12 manufactured by Lintec Co., Ltd. The bump wafer (8 吋 wafer made by Waltz). Further, at the time of attachment, the lamination station of the apparatus was set to 60 ° C, and the laminating rolls were set to 60 ° C. After lamination, the diameter of the circular void generated around the bump was measured from the substrate side using a digital optical microscope (product name "VHX-1000", manufactured by KEYENCE Co., Ltd.). The smaller the diameter of the void, the higher the burial property of the adhesive sheet to the bump. The burying property of the bump was evaluated based on the following criteria. The results are shown in Table 1.

A: The diameter of the void is less than 120 μm.

B: The diameter of the void is 120 μm to 130 μm.

C: Bubbles are associated with adjacent bumps.

[Erosion evaluation]

A 25 mm × 50 mm adhesive sheet was laminated on the mirror wafer. The lamination conditions were the same as those used in the evaluation of the burial property. After merging, visually Observation was made, and the case where no intermediate layer resin was oozing out was rated as A, and the case where oozing was found was rated as C.

[Example 1]

(formation of the middle layer)

40 parts by mass (solid content ratio) of a bifunctional urethane acrylate oligomer (product name "CN9018", manufactured by Arkema Co., Ltd., weight average molecular weight 45000) was used as a polyfunctional compound, and stearyl acrylate was blended ( STA) 60 parts by mass (solid content ratio) as a crystalline monomer and 2,4,6-trimethylbenzylidene-diphenyl-phosphine oxide (product name "Darocue TPO", manufactured by BASF Corporation) 2.0 parts by mass (solid content ratio) was used as a photopolymerization initiator to obtain a UV-curable intermediate layer composition. In the release film of the polyethylene terephthalate (PET) film system (product name "SP-PET381031", manufactured by Lintec Co., Ltd., thickness: 38 μm), the intermediate layer was used as a fountain die. The composition was applied to a thickness of 200 μm after hardening to form a coating film.

Thereafter, the coating film was cured by irradiating ultraviolet rays from the coating film side, and a substrate composed of a polyethylene terephthalate (PET) film having a thickness of 50 μm was laminated on the coating film to form a thickness of 200 μm on the substrate. Floor. In addition, as a UV irradiation device, a high-pressure mercury lamp (product name "H04-L41", Eye Graphics Co., Ltd.) is used as the ultraviolet irradiation device by the ultraviolet irradiation device (product name "ECS-401GX", manufactured by Eye Graphics Co., Ltd.). The ultraviolet ray is used as the ultraviolet ray, and the illuminance is 190 mW/cm ² at a light wavelength of 365 nm, and the light amount is 113 mJ/cm ² (measured in an ultraviolet light meter (product name "UVPF-A1", manufactured by Eye Graphics Co., Ltd.)) Implemented under conditions.

(formation of adhesive sheets)

A copolymer (Mw: 1.3 million) obtained by copolymerizing 94% by mass of 2-ethylhexyl acrylate and 6% by mass of 2-hydroxyethyl acrylate in a solvent, and 50 with respect to the total hydroxyl group 100 parts by mass (solid content ratio) of the acrylic copolymer obtained by reacting 2% of the isocyanatoethyl methacrylate, and a TDI isocyanate crosslinking agent (product name "BHS-8515", Toyo -0.19 parts by mass (solid content ratio) and a photopolymerization initiator (product name "IRGACURE 184", manufactured by BASF Corporation) of 0.748 parts by mass (solid content ratio) to prepare an acrylic adhesive Coating solution.

This was applied onto a release film, and dried by heating to obtain an adhesive layer having a thickness of 10 μm on the release film. The adhesive sheet is obtained by bonding this to the intermediate layer obtained above.

[Embodiment 2]

The polyfunctional compound was used in the same manner as in Example 1 except that the liquid butadiene polymer having a plurality of vinyl groups in the side chain (product name "Ricon 154", manufactured by Cray Valley Co., Ltd., weight average molecular weight: 5,200) was used. Get the adhesive sheet.

[Example 3]

In the same manner as in Example 1, except that the polyfunctional compound was used in a bifunctional polyalkyl acrylate (product name "RC100C", manufactured by Kaneka Co., Ltd., weight average molecular weight: 20000) having a polymerizable functional group at both terminals. Implementation.

[Examples 4 to 6]

The same procedure as in Example 1 was carried out except that the type of the polyfunctional compound, the polyfunctional compound, and the mass fraction of the monofunctional monomer were changed as shown in Table 1.

[Examples 7 to 9]

In addition to the monofunctional monomer of stearyl acrylate, and isodecyl acrylate (IBXA) or 2-hydroxy-3-phenoxypropyl acrylate (HPPA) to the intermediate layer composition, and will The compounding amount of the polyfunctional compound and the monofunctional monomer was changed as shown in Table 1, and the other methods were carried out in the same manner as in Example 1.

[Comparative Example 1]

As shown in Table 1, except for the substitution of the bifunctional urethane acrylate, a monofunctional acrylate resin (product name "MM110C", manufactured by Kaneka Co., Ltd., weight average molecular weight of 9930) was used instead. Example 1 was carried out in the same manner.

[Comparative Example 2]

The amount of the bifunctional urethane acrylate oligomer and the photopolymerization initiator was changed as shown in Table 1, except that the composition for the intermediate layer was not blended with the stearic acid acrylate. Others were carried out in the same manner as in Example 1.

[Comparative Example 3, 4]

In addition to the monofunctional monomer stearyl acrylate, and isodecyl acrylate (IBXA) were blended into the composition for the intermediate layer, and the blending amount of the polyfunctional compound and the monofunctional monomer was changed as shown in Table 1. Other than that shown, the other system was carried out in the same manner as in the first embodiment.

[Table 1] In addition, the mass part of each compound in Table 1 is represented by the amount of solid content. Also, the empty column represents no match. * Each compound in the table is as follows.

(1) Polyfunctional compounds

UA: 2-functional urethane acrylate oligomer (product name "CN9018", manufactured by Arkema Co., Ltd.)

PB: liquid butadiene polymer (product name "Ricon154", manufactured by Cray Valley)

PAA: 2-functional polyalkyl acrylate (product name "RC100C", manufactured by Kaneka Co., Ltd.)

(2) Monofunctional A

Monofunctional acrylate resin (product name "MM110C", manufactured by Kaneka Co., Ltd.)

(3) Monofunctional monomer

STA: stearic acid acrylate

IBXA: isodecyl acrylate

HPPA: 2-hydroxy-3-phenoxypropyl acrylate

In each of the above embodiments, the intermediate layer composition contains at least a polyfunctional compound and a crystalline monomer, and the content of the polyfunctional compound is more than 25% by mass of the monofunctional monomer, and 40% by mass of the monofunctional monomer. The above is a crystalline monomer, so it can be formed on the surface of the wafer by means of an adhesive sheet. The bumps are properly buried and no bleeding occurs when the adhesive sheets are attached to the wafer.

On the other hand, in Comparative Example 1, although the composition for an intermediate layer contains a crystalline monomer, since the monofunctional acrylate resin is used instead of the polyfunctional compound, the burying property to the bump is sufficient, but it cannot be prevented. Exudation of the intermediate layer. Further, as shown in Comparative Examples 2 to 4, when the content of the polyfunctional compound was small in the case where the monofunctional monomer was not blended, the burying property of the bump was not sufficient.

10A‧‧‧Adhesive tablets

11‧‧‧Substrate

12‧‧‧Intermediate

13‧‧‧Adhesive layer

Claims (9)

An adhesive sheet comprising a substrate, an intermediate layer, and an adhesive layer of an adhesive layer, wherein the intermediate layer is formed by hardening an intermediate layer containing a polyfunctional compound and a monofunctional monomer. The polyfunctional compound has at least two polymerizable functional groups, and the monofunctional monomer contains at least a crystalline monomer having a carbon chain having a linear carbon number of 14 to 22, and the intermediate layer composition contains the above polyfunctional compound. The compound was more than 25% by mass of the aforementioned monofunctional monomer. The adhesive sheet of claim 1, wherein 40% by mass or more of the aforementioned monofunctional monomer is the aforementioned crystalline monomer. The adhesive sheet of claim 1 or 2, wherein the polyfunctional compound is a polyfunctional oligomer having a weight average molecular weight of 3,000 to 60,000. The adhesive sheet according to any one of claims 1 to 3, wherein the polymerizable functional group of the polyfunctional compound is a group having an ethylenic double bond. The adhesive sheet according to any one of claims 1 to 4, wherein the polyfunctional compound is selected from the group consisting of urethane (meth) acrylate oligomers, acrylic polymers, and butadiene polymers. At least one of the groups. The adhesive sheet according to any one of claims 1 to 5, wherein the crystalline monomer is contained in an amount of 25 to 70% by mass based on the total amount of the intermediate layer composition. The adhesive sheet according to any one of claims 1 to 6, wherein the composition for the intermediate layer is an energy ray-curable type. The adhesive sheet according to any one of claims 1 to 7, wherein the foregoing intermediate The thickness of the layer is 150 to 700 μm. The adhesive sheet according to any one of claims 1 to 8, which is a tape for semiconductor wafer protection.