JP2003013011A - Removable pressure-sensitive adhesive and removable pressure-sensitive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a removable pressure-sensitive adhesive containing a radiation-sensitive polymer having a side chain into which a carbon-carbon double bond is introduced as a base polymer, capable of preventing penetration of an etchant, cutting water, etc., into an interface between a sheet and a wafer, etc., and having no problem on chipping, and to provide a removable pressure- sensitive adhesive sheet to which a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive is applied. SOLUTION: This removable pressure-sensitive adhesive contains the radiation-sensitive polymer obtained by reacting (A) a polymer which has a functional group (a) in the side chain with (B) a compound which has a functional group (b) having reactivity with the functional group (a) and has the coarbon-carobn double bond as a main component, wherein the radiation- sensitive polymer has such a composition that a ratio of a component having a molecular weight of <=100,000 is not more than 10 wt.%.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a removable pressure sensitive adhesive and a removable pressure sensitive adhesive sheet provided with a pressure sensitive adhesive layer formed from the removable pressure sensitive adhesive. The removable adhesive sheet is a protective sheet used to protect the front surface of the wafer in the grinding process of grinding the back surface of the semiconductor wafer in the process of manufacturing various semiconductors, and cuts the semiconductor wafer into element pieces.
It is useful as an adhesive sheet for dicing, which is divided and attached to the back surface of a wafer in a dicing process of automatically collecting the element small pieces by a pickup method.

[0002]

2. Description of the Related Art In recent years, the size of semiconductor wafers has been increasing and the thickness of wafers for use in IC cards has been decreasing.
The use of radiation-curable pressure-sensitive adhesive sheets is increasing.

In general, a radiation-curable pressure-sensitive adhesive for forming a pressure-sensitive adhesive layer of a radiation-curable pressure-sensitive adhesive sheet has a high molecular weight compound called a base polymer with a weight average molecular weight of 20,000 or less and a carbon-carbon double bond in the molecule. A radiation-polymerizable compound (radiation-reactive oligomer, etc.), a radiation-polymerizable initiator,
Furthermore, it is prepared by appropriately adding various additives such as a crosslinking agent. Usually, a so-called polyfunctional compound having two or more carbon-carbon double bonds in one molecule is often used as the radiation-polymerizable compound in order to impart the property that the adhesive strength is largely reduced after irradiation with radiation. ing. When such a radiation-curable pressure-sensitive adhesive is irradiated with radiation, the radiation-polymerizable compound reacts to form a three-dimensional network structure rapidly, and the pressure-sensitive adhesive as a whole reacts and cures rapidly, resulting in a decrease in the adhesive strength. Has been done. However, this reaction
Curing involves a large volume shrinkage of the adhesive, and the shrinkage stress caused by this shrinks the adhesive itself due to radiation irradiation,
Since the contracting force at this time bends the wafer, there arises a problem that it becomes difficult to carry the wafer within the manufacturing process. At the same time, in the process of cutting and separating the semiconductor element and then picking it up, so-called dicing process, when a pressure-sensitive adhesive sheet composed of a pressure-sensitive adhesive with a large volume shrinkage is used, the sheet cannot be expanded sufficiently and dicing is performed. Since the streets were not expanded, there was a problem that it hindered pickup. Therefore, as a radiation-curable pressure-sensitive adhesive, there has been proposed a protective sheet having a pressure-sensitive adhesive layer made of a radiation-reactive polymer having a specific carbon-carbon double bond introduced into a side chain as a base polymer (Japanese Patent Laid-Open No. 200-200200).
0-355678). With such a protective sheet, the above problem can be solved.

In addition to the above problems, when processing a large-sized wafer or a thin-shaped wafer, an etching process may be performed, and an etching solution or grinding water penetrates between the protective sheet and the wafer, so that the wafer may be exposed. Since there are problems such as contamination and cracks during grinding, the protective sheet is also required to be able to protect the wafer from the etching solution. Also, in the step of soaking the semiconductor element into chips and separating them, and further picking them up, so-called dicing step, there is a problem that cutting water permeates between the chips and the protective sheet, resulting in frequent chipping.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to a removable pressure-sensitive adhesive containing as a base polymer a radiation-reactive polymer having a carbon-carbon double bond introduced into its side chain, which is applied to the interface between a wafer and a sheet. It is possible to prevent the intrusion of etching liquid, cutting water, etc., and to provide a re-peelable pressure-sensitive adhesive without the problem of chipping. Furthermore, a re-peelable pressure-sensitive adhesive sheet provided with a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive is provided. The purpose is to provide.

[0006]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the re-peelable pressure-sensitive adhesive and the re-peelable pressure-sensitive adhesive sheet shown below can achieve the above object, The present invention has been completed.

That is, the present invention provides a polymer (A) having a functional group a in its side chain, and a compound (B) having a functional group b reactive with the functional group a and a carbon-carbon double bond.
In the removable pressure-sensitive adhesive containing the radiation-reactive polymer as a main component, the ratio of the components having a molecular weight of 100,000 or less in the radiation-reactive polymer is 10 or less.
It relates to a re-peelable pressure-sensitive adhesive characterized by being less than or equal to wt%.

The above-mentioned removable adhesive of the present invention is a radiation-curable adhesive, in which the unreacted radiation-polymerizable compound or the low molecular weight component in the base polymer is retained on the wafer by the infiltration of an etching solution or cutting water. It was found that the radiation-reactive polymer has a carbon-carbon double bond introduced into its side chain, and the ratio of the component having a molecular weight of 100,000 or less is 10% by weight or less. Is used. This prevents the etching liquid and cutting water from entering the interface between the wafer and the sheet, thus preventing contamination. Further, by preventing liquid from entering the interface between the wafer and the sheet, cracks during grinding and chipping during dicing are suppressed. Further, the pressure-sensitive adhesive sheet using the re-peelable pressure-sensitive adhesive of the present invention can prevent the contamination of the wafer since the pressure-sensitive adhesive does not remain on the wafer surface after peeling. Furthermore, since the pressure-sensitive adhesive of the present invention uses the radiation-reactive polymer having the carbon-carbon double bond introduced into the side chain as a base polymer, there is no problem associated with volume shrinkage.

The proportion of the component having a molecular weight of 100,000 or less in the radiation-reactive polymer is preferably as small as possible, more preferably 8% by weight or less, and further preferably 5% by weight or less. In addition, the ratio of the component having a molecular weight of 100,000 or less should be calculated from the integral molecular curve obtained by measurement by GPC (gel permeation chromatography) to calculate the ratio (area) of the component having a molecular weight of 100,000 or less to the whole. Sought by.

In the removable pressure-sensitive adhesive, the side chain length having a carbon-carbon double bond formed in the radiation-reactive polymer is preferably 6 or more in terms of the number of atoms.

When the number of atoms in the side chain is 6 or more,
Since the side chain is long, the shrinkage force resulting from the curing reaction is extremely reduced, and the shrinkage force of the pressure-sensitive adhesive layer after curing can be reduced to 30 MPa or less. When the number is less than 6, the side chain length is short, so that the polymer after the radiation curing reaction becomes rigid and the shrinkage force tends to increase. Shrinkage force is JP 2000-3
It is measured by the method described in Japanese Patent No. 55678.

The side chain length in the polymer molecule means that in the side chain, an atom other than a hydrogen atom (a carbon atom, an oxygen atom, a nitrogen atom, or another atom or two or more atomic groups) is bonded. It refers to the number of the atoms in the straight-chain portion that maximizes the number of bonds (obtained atoms, etc.).

The present invention also relates to a removable pressure sensitive adhesive sheet having a pressure sensitive adhesive layer comprising the removable pressure sensitive adhesive on a substrate film.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A radiation-reactive polymer which is a main component of a removable pressure-sensitive adhesive comprises a polymer (A) having a functional group a in its side chain, a functional group b reactive with the functional group a, and It is obtained by reacting a compound (B) having a carbon-carbon double bond. The functional group a of the polymer (A) and the functional group b of the compound (B) are preferably those capable of reacting (condensation, addition reaction, etc.) while maintaining the carbon-carbon double bond of the compound (B).

As the functional group a and the functional group b, for example,
Examples thereof include a carboxyl group, an acid anhydride group, a hydroxyl group, an amino group, an epoxy group, an isocyanate group, and an aziridine group. Among these, a combination capable of reacting with each other can be appropriately selected and used. For example, a combination of the functional group a and the functional group b includes a carboxyl group and an epoxy group,
It includes a carboxyl group and an aziridine group, a hydroxyl group and an isocyanate group, a carboxyl group and a hydroxyl group, and the like. In these combinations, either the left or right may be the functional group a (or the functional group b). Among the combinations of the functional group a and the functional group b, the combination of the hydroxyl group and the isocyanate group is preferably used from the viewpoint of easy reaction tracking.

Polymer (A) having functional group a in its side chain
Is not particularly limited as long as it can exhibit adhesiveness, but an acrylic polymer is preferable from the viewpoint of easy molecular design.

The acrylic polymer is, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group,
n-butyl group, t-butyl group, isobutyl group, amyl group, isoamyl group, hexyl group, heptyl group, cyclohexyl group, 2-ethylhexyl group, octyl group, isooctyl group, nonyl group, isononyl group, decyl group, isodecyl group Group, undecyl group, lauryl group, tridecyl group, tetradecyl group, stearyl group, octadecyl group, dodecyl group, etc., having a straight or branched alkyl group having 1 to 30 carbon atoms, particularly 4 to 18 carbon atoms (meth) acryl Acid alkyl ester {(meth) acrylic acid ester means acrylic acid ester and / or methacrylic acid ester, and (meth) of the present invention has the same meaning}
It can be obtained by copolymerizing a monomer having a functional group a with one or two or more main components.

Examples of the monomer having a functional group a include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid; maleic anhydride; Acid anhydride group-containing monomers such as itaconic anhydride; (meth) acrylic acid 2
-Hydroxyethyl, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, (meth) acrylic acid 10 -Hydroxydecyl, (meth) acrylic acid 1
Hydroxyl group-containing monomers such as 2-hydroxylauryl, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. ;
Examples thereof include epoxy group-containing monomers such as glycidyl (meth) acrylate and allyl glycidyl ether. These monomers having the functional group a may be used alone or in combination of two or more. The amount of the monomer having the functional group a used is preferably 50% by weight or less of the total monomer components.

For the purpose of modifying cohesive strength, heat resistance and the like, the acrylic polymer may be added with styrene sulfonic acid, allyl sulfonic acid, 2
-(Meth) acrylamido-2-methylpropanesulfonic acid, (meth) acrylamidopropanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalenesulfonic acid and other sulfonic acid group-containing monomers; 2-hydroxyethylacryloyl phosphate A phosphoric acid group-containing monomer such as acrylonitrile; a cyano group-containing monomer such as acrylonitrile; an amide group-containing monomer such as acrylamide; an amino group-containing monomer such as N, N-dimethylaminoethyl (meth) acrylate;
-Acryloylmorpholine; vinyl esters such as vinyl acetate; aromatic vinyl compounds such as styrene; vinyl ethers such as vinyl ethyl ether. These monomer components may be used alone or in combination of two or more. When vinyl esters such as vinyl acetate are used as comonomer components, the monomers are polymerized and then saponified,
It is also possible to introduce hydroxyl groups into the polymer side chains.

Furthermore, the acrylic polymer may contain a polyfunctional monomer or the like as a monomer component for copolymerization, if necessary, for the purpose of crosslinking treatment. Examples of such polyfunctional monomers include hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, Pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate
Acrylate, dipentaerythritol hexa (meth)
Examples thereof include acrylate, epoxy (meth) acrylate, polyester (meth) acrylate, urethane (meth) acrylate and the like. These polyfunctional monomers may be used alone or in combination of two or more. The amount of the polyfunctional monomer used is preferably 30% by weight or less of the total monomer components from the viewpoint of adhesive properties and the like.

The acrylic polymer (A) having the functional group a in its side chain can be prepared by any polymerization method such as solution polymerization, emulsion polymerization, bulk polymerization and suspension polymerization.

As the functional group b reactive with the functional group a of the polymer (A) and the compound (B) having a carbon-carbon double bond, those having a functional group b capable of reacting with the functional group a are appropriately used. Select and use. For example, when the functional group a is a hydroxyl group, an isocyanate compound having a (meth) acroyl group in the molecule such as methacryloyl isocyanate and 2-methacryloyloxyethyl isocyanate as the compound (B); m-isopropenyl-α, α
Examples thereof include isocyanate compounds having a vinyl group-containing aromatic ring in the molecule such as dimethylbenzyl isocyanate. When the functional group a is a carboxyl group, the compound (B) may be an epoxy compound having a carbon-carbon double bond such as glycidyl (meth) acrylate.

The amount of carbon-carbon double bond in the radiation-reactive polymer is determined according to JIS K considering the preservability of the pressure-sensitive adhesive.
The iodine value according to -0070 is preferably 30 or less, and more preferably 0.5 to 20.

The compound (B) preferably has one carbon-carbon double bond. The compound (B) may have two or more carbon-carbon double bonds, but in that case, an excessive three-dimensional network structure is formed by the radiation curing reaction, the polymer molecule becomes rigid after curing, and the shrinkage force is increased. It tends to increase, which is not preferable.

The weight average molecular weight of the radiation-reactive polymer is preferably 150,000 to 1,500,000, more preferably 3
It is from 0,000 to 1,200,000. The method for reducing the low molecular weight component of the radiation reactive polymer is not particularly limited, and examples thereof include a method of purifying the obtained radiation reactive polymer by a reprecipitation method or the like to remove the low molecular weight component. These methods can also be performed on the polymer (A) before reacting with the compound (B). It was also prepared by adopting living radical polymerization utilizing oxidation / reduction reaction of metal, initiation of coordination polymerization using a samarium complex as an initiator, and living polymerization method in which the polymerization reaction proceeds while controlling the growth reaction. By using the polymer (A), it is possible to obtain a radiation-reactive polymer having a reduced low molecular weight component.

The releasable pressure-sensitive adhesive is cured by irradiation with radiation such as X-rays, ultraviolet rays and electron beams. When the pressure-sensitive adhesive layer is cured by ultraviolet rays or the like, it contains a photopolymerization initiator. Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α′-dimethylacetophenone, 2-methyl-2-hydroxypropio. Α-ketol compounds such as phenone and 1-hydroxycyclohexyl phenyl ketone; methoxyacetophenone,
2,2-dimethoxy-2-phenylacetophenone,
2,2-diethoxyacetophenone, 2-methyl-1-
Acetophenone compounds such as [4- (methylthio) -phenyl] -2-morpholinopropane-1; benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether and anisoin methyl ether; ketals such as benzyl dimethyl ketal Compounds; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2- (o-ethoxycarbonyl) oxime; benzophenone, benzoylbenzoic acid , 3,3′-Dimethyl-4-methoxybenzophenone and other benzophenone compounds; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxane Compounds such as benzene, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; camphorquinone; halogenated ketones; acylphosphinoxides; acylphosphonates And so on.

The photopolymerization initiator is blended in an amount of 0.1 parts by weight or more, and further 0.5 parts by weight, based on 100 parts by weight of a base polymer such as an acrylic polymer which constitutes the pressure-sensitive adhesive. The above is preferable. If the amount is too large, the preservability of the pressure-sensitive adhesive tends to decrease.
It is preferably not more than 5 parts by weight, more preferably not more than 5 parts by weight.

A crosslinking agent can be added to the removable pressure-sensitive adhesive to control the crosslinking density of the pressure-sensitive adhesive layer. Examples of the cross-linking agent include polyfunctional isocyanate compounds, epoxy compounds, melamine compounds, metal salt compounds, metal chelate compounds, amino resin compounds, and peroxides. When a cross-linking agent is used, the amount thereof is not particularly limited, and is generally based on 100 parts by weight of the radiation-reactive polymer that is the base polymer, and generally based on 100 parts by weight of the base polymer. ,
It is preferable to add about 0.1 to 5 parts by weight.

The re-peelable pressure-sensitive adhesive may contain a radiation-reactive oligomer, a monomer, etc., as long as the object of the present invention is not impaired. As the radiation-reactive oligomer, various oligomers such as urethane-based, polyether-based, polyester-based, polycarbonate-based and polybutadiene-based can be appropriately selected and used. These radiation-reactive oligomers can be used alone or in combination of two or more.

In addition to the above-mentioned components, the re-peelable pressure-sensitive adhesive may contain various conventionally known tackifiers, if necessary.
You may use additives, such as an antioxidant, a plasticizer, and a vulcanization agent.

Hereinafter, the removable pressure-sensitive adhesive sheet of the present invention is shown in FIG.
Will be described in detail with reference to. As shown in FIG. 1, in the removable pressure-sensitive adhesive sheet of the present invention, a pressure-sensitive adhesive 2 is provided on a base film 1. Moreover, the separator 3 is provided on the pressure-sensitive adhesive layer 2 as needed. In FIG. 1, the pressure-sensitive adhesive layer 2 is provided on one side of the base film 1, but these may be formed on both sides of the base film 1. The removable pressure-sensitive adhesive sheet can be formed into a shape corresponding to the planar shape of an object to be cut such as a substrate or a wafer, or an appropriate form such as a continuous sheet,
It is also possible to wind the sheet into a tape shape.

The material of the substrate film 1 is not particularly limited, but it is preferable to use a material that transmits at least a part of a predetermined or more energy ray. For example, generally for wafer grinding applications, low density polyethylene, linear polyethylene, medium density polyethylene, high density polyethylene, ultra low density polyethylene, random copolymer polypropylene, block copolymer polypropylene, homopolyprolene, polybutene, polymethylpentene. Such as polyolefin, ethylene-vinyl acetate copolymer, ionomer resin, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid ester (random, alternating) copolymer, ethylene-butene copolymer, Polymers such as ethylene-hexene copolymers, polyurethanes, polyesters such as polyethylene terephthalate, polyimides, polyether ether ketones, fluororesins, cellulosic resins and crosslinked products thereof can be mentioned. Wafer cutting
For the purpose of separation, in addition to the above various films, polyvinyl chloride and soft polyvinyl chloride using polyvinylidene chloride are often used.

The thickness of the substrate film 1 can be appropriately selected within a range that does not impair the operability and workability in the application, but is usually about 500 μm or less, preferably about 3 to 300 μm, and more preferably about 5 to 250 μm. is there. The base film 1 can be formed by a conventionally known film forming method. For example, a wet casting method, an inflation extrusion method, a T-die extrusion method or the like can be used. The base film 1 may be used without being stretched, or may be subjected to a uniaxial or biaxial stretching treatment as needed. Further, on the surface of the base material film 1, if necessary, a chemical or physical treatment such as chromic acid treatment, ozone exposure, flame exposure, high piezoelectric bombardment exposure, ionizing radiation treatment, an undercoating agent (for example, an adhesive substance described later). ) May be applied.

The thickness of the pressure-sensitive adhesive layer 2 may be appropriately selected,
Generally about 1 to 300 μm or less, preferably 3 to 20
It is 0 μm, and more preferably 5 to 100 μm. The adhesive strength of the adhesive layer may be appropriately determined according to the purpose of use, etc. However, in general, the adhesive strength before irradiation (23 ° C , 180 ° peel value, peeling speed 300mm
/ Min) is preferably 1 N / 25 mm tape width or more and the adhesive force after irradiation with radiation is 0.4 N / 25 mm tape width or less.

The removable pressure-sensitive adhesive sheet of the present invention can be produced by, for example, a method of applying a removable pressure-sensitive adhesive to the base film 1 to form the pressure-sensitive adhesive layer 2.
In addition, after separately forming the pressure-sensitive adhesive layer 2 on the separator 3,
A method in which this is attached to the base film 1 can be adopted.

The pressure-sensitive adhesive layer 2 of the removable pressure-sensitive adhesive sheet is provided with the separator 3 until it is adhered to an object to be cut such as a semiconductor wafer from the viewpoint of preventing contamination during storage and distribution.
It is preferable to coat and protect with. The constituent material of the separator 3 is paper, polyethylene, polypropylene,
Examples thereof include synthetic resin films such as polyethylene terephthalate. In order to enhance the peeling property, the surface of the separator 3 may be treated with silicone, long-chain alkyl, or
Release treatment such as fluorine treatment may be performed. The thickness of the separator 3 is usually 10 to 200 μm, preferably 2
It is about 5 to 100 μm.

[0037]

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

Example 1 (Preparation of acrylic copolymer) 0.59 mol of ethyl acrylate, 0.59 mol of butyl acrylate, 0.26 mol of 2-hydroxyethyl acrylate and 2,2 '
-2 mmol of azobisisobutyronitrile was added to a high-pressure container made of stainless steel with a content of 500 ml at a temperature of 25 ° C so that the total amount would be 200 g, and the mixture was stirred with vitiligo blades to obtain high purity in the removed place. Pour carbon dioxide 2
The pressure was once kept at MPa. After a few seconds, carbon dioxide was discharged from the discharge port and the air remaining in the high-pressure tank was replaced with carbon dioxide. After the above operation, similarly, high-purity carbon dioxide was added at 25 ° C., and the pressure was once maintained at 7 MPa. Then, the container was pressurized to raise the internal temperature to 60 ° C. When the temperature reached 60 ° C., high-purity carbon dioxide was charged again to adjust the internal pressure to 20 MPa. This state was maintained for about 12 hours for polymerization to obtain a polymer solution.

(Preparation of Radiation Reactive Polymer) Subsequently, 0.21 mol of 2 was added to the acrylic copolymer.
-A methacryloyloxyethyl isocyanate was subjected to an addition reaction to obtain a radiation-reactive polymer in which a carbon-carbon double bond was introduced into the inner chain of the polymer molecule. The side chain length in the polymer molecule was 13 in number of atoms. The weight average molecular weight of the obtained radiation-reactive polymer measured by GPC method is 800,000, and the component having a molecular weight of 100,000 or less is 5.2% by weight.
Met.

(Preparation of Removable Pressure-Sensitive Adhesive Sheet) 1 part by weight of a polyisocyanate-based crosslinking agent and 3 parts by weight of an acetophenone-based photopolymerization initiator were mixed with 100 parts by weight of the radiation-reactive polymer. 30μ by applying the removable adhesive on the release-treated film
An m-thick adhesive layer was formed. This adhesive layer has a thickness of 10
A re-peelable pressure-sensitive adhesive sheet was obtained by coating on a 0 μm polyolefin film.

Example 2 (Preparation of acrylic copolymer) Thermometer, stirrer,
500m capacity with nitrogen inlet and reflux condenser
In a three-necked reactor (1), 0.59 mol of ethyl acrylate, 0.59 of n-butyl acrylate, 0.26 mol of 6-hydroxyhexyl acrylate, 2,2'-azobisisobutyronitrile 2 mmol and toluene total 2
The mixture was added so that the amount became 00 g, the mixture was charged, and the mixture was stirred while introducing nitrogen gas for about 1 hour to replace the internal air with nitrogen.
After that, the internal temperature was set to 60 ° C., and this state was maintained for about 6 hours to carry out polymerization to obtain a polymer solution.

(Preparation of Radiation Reactive Polymer) Subsequently, 0.21 mol of 2 was added to the acrylic copolymer.
-A methacryloyloxyethyl isocyanate was subjected to an addition reaction to obtain a radiation-reactive polymer in which a carbon-carbon double bond was introduced into the inner chain of the polymer molecule. The side chain length in the polymer molecule was 16 atoms. The resulting radiation-reactive polymer was purified by the methanol reprecipitation method to remove low molecular weight components. GP of this radiation-reactive polymer
The weight average molecular weight measured by the C method was 600,000, and the component having a molecular weight of 100,000 or less was 7.3% by weight. In addition, after that, a re-peelable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1.

Example 3 0.59 mol of 2-ethylhexyl acrylate, 0.59 mol of N-acryloylmorpholine, 0.26 mol of 2-hydroxyethyl acrylate and 2,2'-azobisisobutyronitrile 2 200 milligrams of millimoles in a high pressure vessel made of stainless steel with a capacity of 500 ml at 25 ° C.
High purity carbon dioxide was poured into the removed place while stirring with a vitiligo blade, and the pressure was once maintained at 2 MPa. After a few seconds, carbon dioxide was discharged from the discharge port and the air remaining in the high-pressure tank was replaced with carbon dioxide.
After the above operation, similarly, high-purity carbon dioxide was added at 25 ° C., and the pressure was once maintained at 7 MPa. afterwards,
The container was pressurized to raise the internal temperature to 60 ° C. When the temperature reached 60 ° C., high-purity carbon dioxide was charged again to adjust the internal pressure to 20 MPa. This state was maintained for about 12 hours for polymerization to obtain a polymer solution.

Thereafter, a radiation-reactive polymer was prepared in the same manner as in Example 1. The side chain length in the polymer molecule was 10 in terms of the number of atoms. GP of the resulting radiation-reactive polymer
The weight average molecular weight measured by the C method was 1.2 million, and the component having a molecular weight of 100,000 or less was 4.1% by weight. Also,
A releasable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1.

Example 4 (Preparation of acrylic copolymer) Thermometer, stirrer,
500m capacity with nitrogen inlet and reflux condenser
In a three-necked reactor (1), 0.59 mol of ethyl acrylate, 0.59 mol of n-butyl acrylate and 0.26 mol of acrylic acid, 2 mmol of 2,2'-azobisisobutyronitrile and Toluene was blended and added so that the total amount became 200 g, and the mixture was stirred while introducing nitrogen gas for about 1 hour, and the air inside was replaced with nitrogen. After that, the internal temperature was set to 60 ° C., and this state was maintained for about 6 hours to carry out polymerization to obtain a polymer solution.

(Preparation of Radiation Reactive Polymer) Subsequently, 0.21 mol of glycidyl methacrylate was added to the acrylic copolymer to cause a radiation reaction in which a carbon-carbon double bond was introduced into the inner chain of the polymer molecule. A polymerizable polymer was obtained. The side chain length in the polymer molecule is 9 in terms of the number of atoms.
It was an individual. The resulting radiation-reactive polymer was purified by the methanol reprecipitation method to remove low molecular weight components. The weight average molecular weight of this radiation-reactive polymer measured by the GPC method was 750,000, and the content of the component having a molecular weight of 100,000 or less was 8.8% by weight.

In the following, the re-peelable pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that 0.1 part by weight of the epoxy crosslinking agent was used instead of 1 part by weight of the polyisocyanate crosslinking agent. Got

Example 5 In the preparation of the removable pressure-sensitive adhesive sheet of Example 1, the radiation-reactive polymer obtained in Example 3 was used as the radiation-reactive polymer, the thickness of the pressure-sensitive adhesive layer was 10 μm, and the substrate was The thickness of the polyolefin film is 70 μm
A re-peelable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except for the above.

Comparative Example 1 (Preparation of Acrylic Copolymer) Thermometer, Stirrer,
500m capacity with nitrogen inlet and reflux condenser
In a three-necked reactor (1), 0.59 mol of ethyl acrylate, 0.59 mol of n-butyl acrylate and 0.26 mol of 2-hydroxyethyl acrylate, 2,2'-azobisisobutyro 2 mmol of nitrile and ethyl acetate were mixed and added so that the total amount became 200 g, and the mixture was stirred while introducing nitrogen gas for about 1 hour, and the air inside was replaced with nitrogen. After that, the internal temperature was set to 60 ° C., and this state was maintained for about 9 hours for polymerization to obtain a polymer solution.

Thereafter, a radiation-reactive polymer was prepared in the same manner as in Example 1. The weight average molecular weight of this radiation-reactive polymer measured by GPC method is 500,000, and the molecular weight is 1
The amount of components of less than 0,000 was 32.2% by weight. Further, a re-peelable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1.

Comparative Example 2 (Preparation of Acrylic Copolymer) Thermometer, Stirrer,
500m capacity with nitrogen inlet and reflux condenser
In a three-necked reactor (1), 0.59 mol of ethyl acrylate, 0.59 mol of n-butyl acrylate and 0.26 mol of 6-hydroxyethyl acrylate, 2,2'-azobisisobutyro 2 mmol of nitrile and ethyl acetate were mixed and added so that the total amount became 200 g, and the mixture was stirred while introducing nitrogen gas for about 1 hour, and the air inside was replaced with nitrogen. After that, the internal temperature was set to 60 ° C., the state was kept for about 6 hours to carry out the polymerization, the temperature was further raised to 80 ° C., and the state was kept for about 2 hours to obtain a polymer solution.

Thereafter, a radiation-reactive polymer was prepared in the same manner as in Example 1. The weight average molecular weight of this polymer measured by the GPC method was 650,000, and the component having a molecular weight of 100,000 or less was 18.8% by weight. Further, a re-peelable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1.

Comparative Example 3 In the production of the removable pressure-sensitive adhesive sheet of Example 1, the radiation-reactive polymer obtained in Comparative Example 2 was used as the radiation-reactive polymer, the thickness of the pressure-sensitive adhesive layer was 10 μm, and the substrate was used. The thickness of the polyolefin film is 70 μm
A re-peelable pressure-sensitive adhesive sheet was obtained in the same manner as in Example 1 except for the above.

The re-peelable pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were evaluated as follows. The results are shown in Table 1.

(Water Infiltration Distance with Etching Liquid) The re-peelable pressure-sensitive adhesive sheets obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were used as pressure-sensitive adhesive sheets for wafer grinding, and the edges of the wafer after etching and grinding were performed. The liquid penetration distance from the part was measured by an optical microscope (× 200 times). Etching conditions,
The conditions for grinding the back surface of the wafer, the conditions for irradiating ultraviolet rays, etc. are as follows.

<Etching conditions> Etching solution concentration: HF / HNO ₃ / CH ₃ COOH =
1/3/1 (weight ratio) Immersion time: 3 min Method: Dipping method Etching amount: 50 μm <Wafer grinding conditions> Grinding machine: Disco DFG-840 Wafer: 6 inch diameter (backside grinding from 600 μm to 200 μm) Scribe line Depth: 10 μm Wafer bonding device: DR-8500II (manufactured by Nitto Seiki Co., Ltd.) Ultraviolet (UV) irradiation device: NEL UM-110 (manufactured by Nitto Seiki Co., Ltd.) Integrated UV irradiation light intensity: 500 mJ / cm ² .

(Defective rate due to chipping) Using the removable pressure-sensitive adhesive sheets obtained in Example 5 and Comparative Example 3 as the pressure-sensitive adhesive sheet for dicing, after dicing under the following dicing conditions, 1000 arbitrary wafer chips were picked up ( Then, chipping on the side surface of the wafer chip was observed. The observed ratio of 0.075 mm triangular chipping was regarded as defective, and the ratio was calculated.

<Wafer dicing conditions> Dicing device: Disco DFD651 Dicing speed: 100 mm / sec Dicing blade: Disco 2050HEDD Dicing blade rotation speed: 40,000 rpm Dicing tape cut depth: 30 μm Wafer chip size: 10 mm x 10 mm Wafer diameter: 6 inches.

(Organic Contamination Against Wafer) The re-peelable pressure-sensitive adhesive sheet pieces prepared in Examples and Comparative Examples were attached to aluminum vapor-deposited wafers, left at 40 ° C. for 1 day, and then the tape pieces were peeled off.
The organic matter transferred onto the wafer is transferred to ESCA (model 5
400 manufactured by ULVAC-PHI, Inc.). Wafers to which no tape was attached were also analyzed in the same manner, and the presence or absence of contamination was evaluated based on the detected amount of increase in carbon atoms and the amount of transferred organic matter according to the following criteria.

[0060] None: When the increase in the transfer amount is 5% or less. Yes: When the increase in the transfer amount is larger than 5%.

[0061]

[Table 1]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a pressure-sensitive adhesive sheet for dicing.

[Explanation of symbols] 1: Base film 2: Adhesive layer 3: Separator

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H01L 21/304 622 H01L 21/78 MF term (reference) 4J004 AA01 AA10 AB01 AB06 CA02 CA03 CA04 CA05 CA06 CC02 CD08 DA01 DA04 DA05 DB02 EA06 FA04 FA05 4J040 DF031 EF102 EF272 GA01 JA09 JB07 JB09 KA13 LA06 LA07 LA08 MA04 MA10 MB03 NA20 PA21 PA32

Claims (3)

[Claims] 1. A polymer (A) having a functional group a in its side chain.
And a radiation-reactive polymer obtained as a main component by reacting the functional group a having a reactivity with the functional group a and the compound (B) having a carbon-carbon double bond. In the re-peelable pressure-sensitive adhesive, the ratio of the component having a molecular weight of 100,000 or less in the radiation-reactive polymer is 10% by weight or less. 2. The side chain having a carbon-carbon double bond formed in the radiation-reactive polymer has a chain length of 6 atoms.
The removable pressure-sensitive adhesive according to claim 1, wherein the removable pressure-sensitive adhesive is one or more. 3. A removable pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer comprising the removable pressure-sensitive adhesive according to claim 1 or 2 on a substrate film.