JPH07242860A - Protection member for semiconductor wafer - Google Patents

Abstract

PURPOSE:To obtain a protection member for the covering of a circuit pattern surface of a semiconductor wafer, having a specific water-swelling tacky adhesive layer on a supporting film, leaving little residual particle contaminant, satisfying peeling releasability and having excellent corrosion protecting property and cleanability. CONSTITUTION:This protection member is composed of (A) a water-swelling tacky adhesive layer 2 having an adhesive force of 50-300g/20 ram to a mirror wafer measured by 180 deg. peeling method and produced by crosslinking a hydrophilic polymer having a weight-average molecular weight of 50,000-3,000,000 and containing (meth)acrylic acid and/or a (meth)acrylic acid derivative capable of forming a homopolymer having a glass transition temperature of <=-10 deg.C as a monomer component with a water-soluble epoxy-based crosslinking agent and/or a water-soluble aziridine-based crosslinking agent up to a gel fraction of >=40% and (B) a supporting film 1 such as a plastic film supporting the tacky adhesive layer A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective member for coating a circuit pattern surface, which is excellent in corrosion resistance of the circuit pattern surface and cleansability with water and is used for polishing the back surface of a semiconductor wafer.

[0002]

2. Description of the Related Art A semiconductor wafer on which a predetermined circuit pattern such as an IC has been formed is subjected to back surface polishing for the purpose of removing an oxide film formed on the back surface and adjusting the thickness. In that case, the semiconductor wafer may be damaged, or the circuit pattern surface may be contaminated or damaged by polishing dust or the like. Therefore, a method of covering the circuit pattern surface with a protective member has been proposed to prevent this. .

Conventionally, as the protective member, one having a water-swellable pressure-sensitive adhesive layer cross-linked with a metal salt-based cross-linking agent on a support film has been known (Japanese Patent Publication No. 5-77284).
Issue). This is because by using a water-swellable pressure-sensitive adhesive, contamination such as adhesive residue (residual pressure-sensitive adhesive) on the circuit pattern surface after peeling off the protective member can be washed away with water. That is, in the case of using an emulsion type acrylic adhesive or the like up to that point, it is necessary to wash the circuit pattern surface after peeling the protective member, pre-wash with an organic solvent such as acetone or isopropyl alcohol, and then wash with water, The use of an organic solvent requires environmental hygiene measures, and also has the drawback that cleaning efficiency is poor due to the large number of steps, and the above-mentioned protective member having a water-swellable pressure-sensitive adhesive layer is intended to overcome such difficulties.

However, the conventional protective member having the water-swellable pressure-sensitive adhesive layer has problems such as corrosion of the circuit pattern of the semiconductor wafer. Such a corrosion problem is a peculiar problem newly caused by using the water-swellable pressure-sensitive adhesive layer, and is a serious problem that makes practical use of the formed IC chip and the like impossible.

[0005]

DISCLOSURE OF THE INVENTION The present invention does not cause adverse effects such as corrosion on a circuit pattern surface, has a small amount of adhesive residue on the circuit pattern surface after peeling, and sufficiently cleans the surface by washing with water. An object of the present invention is to obtain a protective member for covering a circuit pattern surface of a semiconductor wafer, which can be formed without using pre-cleaning with an organic solvent.

[0006]

The present invention is characterized by having a water-swellable pressure-sensitive adhesive layer crosslinked with a water-soluble epoxy crosslinking agent or / and a water-soluble aziridine crosslinking agent on a support film. A protective member for covering a circuit pattern surface of a semiconductor wafer is provided.

[0007]

The present inventors have earnestly studied in order to develop a protective member for covering the circuit pattern surface of a semiconductor wafer, and in the course of this, the problem of circuit pattern corrosion in the conventional protective member having a water-swellable pressure-sensitive adhesive layer. Is a metal ion of a metal salt-based cross-linking agent composed of a polyvalent metal chelate compound or the like, which is adhered and bonded to a wiring or a pad composed of aluminum or the like, which corrodes a circuit pattern and induces a conduction failure or a short circuit. It was clarified that it caused a malfunction. In addition, it was also clarified that non-reactive crosslinking agents remained on the circuit pattern surface and could not be removed by washing with the usual crosslinking agents composed of polyisocyanate compounds, melamine compounds, reactive phenol compounds, water-insoluble epoxy compounds, etc. did.

The present invention is based on the above findings,
By using a water-soluble epoxy-based cross-linking agent or aziridine-based cross-linking agent, it can be dispersed in the water-based pressure-sensitive adhesive with good uniformity, and can be efficiently cross-linked through a cross-linking group such as a carboxyl group in the base polymer, Avoids problems such as circuit pattern corrosion without compromising the advantages of the water-swellable pressure-sensitive adhesive layer, which can wash away contamination such as adhesive residue on the circuit pattern surface after peeling the protective member with water washing treatment and omit pre-washing with an organic solvent. can do.

[0009]

EXAMPLE The protective member of the present invention has a water-swellable pressure-sensitive adhesive layer cross-linked with a water-soluble epoxy crosslinking agent and / or a water-soluble aziridine crosslinking agent on a support film. An example thereof is shown in FIG. Reference numeral 1 is a support film, and 2 is a water-swellable pressure-sensitive adhesive layer. In addition, 3 is a separator.

The support film is provided to alleviate the impact when the back surface of the semiconductor wafer is polished, and to prevent the protective member from being peeled off by being invaded by cleaning water during the polishing. . Therefore, as the support film, one having good water resistance is preferably used. Examples thereof include polyethylene, polypropylene, polyester, polycarbonate, ethylene / vinyl acetate copolymer, ethylene / (meth) acrylate copolymer, ethylene / methyl (meth) acrylate copolymer, ethylene.
Examples thereof include a film having a thickness of 10 to 300 μm and made of a plastic such as an ethyl (meth) acrylate copolymer, an ethylene / propylene copolymer, or polyvinyl chloride.

A good deformable support film made of a rubber-rich plastic such as an ethylene / vinyl acetate copolymer, an ethylene / (meth) acrylate copolymer, or an ethylene / propylene copolymer, of which the elastic modulus is 1
A support film having a weight of 50 kg / cm ² can be advantageously used for forming a protective member having excellent adhesion to a rough surface and excellent semiconductor wafer protecting function.

On the other hand, a support film having rigidity such as polypropylene, polyester, or polycarbonate causes adhesion failure such as bending adhesion (exposure of circuit pattern) when the protective member is automatically adhered to the circuit pattern surface of the semiconductor wafer. This is difficult to do and is advantageous in forming a protective member for use in an automatic bonding device.

Since the water-swellable pressure-sensitive adhesive layer is for bonding the protective member to the circuit pattern surface of the semiconductor wafer to seal it, it is required to have appropriate pressure-sensitive adhesive force and cohesive force (holding force). To be done. By the way, if the adhesive force is too low or the cohesive force is insufficient, the protective member peels off, floats, or shifts when polishing the backside of a semiconductor wafer, resulting in poor polishing accuracy or intrusion of cleaning wastewater into the circuit pattern surface, etc. Induce serious inconvenience. On the other hand, if the adhesive strength is too high, the semiconductor wafer and the circuit pattern surface thereof are damaged when the protective member is peeled off, and adhesive residue is apt to occur, which leads to the inconvenience of requiring many hours for cleaning.

Therefore, as the water-swellable pressure-sensitive adhesive layer in the present invention, a layer in which the pressure-sensitive adhesive force and the cohesive force are appropriately adjusted by crosslinking treatment with a crosslinking agent is used. Its preferred adhesive strength is
Mirror wafer (semiconductor wafer surface before circuit pattern formation)
For 10-600g / 20mm, especially 50-300g
/ 20mm (at room temperature, 180 degree peel value, peeling speed 300mm /
Minutes). The preferred cohesive force is 40% or more, especially 50 to 100% for a polymer having a weight average molecular weight of 50,000 or more.
The gel was crosslinked at the gel fraction of. In particular, a composition in which a polymer having a weight average molecular weight of 50,000 to 3,000,000 is subjected to a crosslinking treatment to suppress the inclusion of a low molecular weight substance is preferable from the viewpoint of reducing the amount of adhesive residue.

Further, the water-swellable pressure-sensitive adhesive layer in the protective member of the present invention can remove stains such as adhesive residue on the circuit pattern surface after the protective member is peeled off by washing with water, and pre-washing with an organic solvent becomes unnecessary. It is for. The formation of such a water-swellable pressure-sensitive adhesive layer is, for example, emulsion polymerization of (meth) acrylic acid ester as a main component, a copolymerizable monomer having the (meth) acrylic acid ester and a crosslinkable functional group, and a modifying monomer as necessary. System, bulk polymerization system, solution polymerization system and the like, which can be carried out by using an adhesive having a hydrophilic polymer prepared by an appropriate polymerization system as a base polymer.

Examples of the above-mentioned pressure-sensitive adhesive include a water-soluble polymer and a (meth) acrylic acid ester monomer forming a water-soluble or water-swellable polymer as components (JP-A-59-157162). A copolymer salt obtained by neutralizing a carboxyl group in a copolymer composed of a monomer containing a carboxyl group and an alkyl (meth) acrylate, and represented by the general formula: R ⁴ O (R ⁵ O) _m R ^6. Examples thereof include those containing a hydrophilic compound as a component (JP-A-56-70077).

Specific examples of the water-soluble polymer include, for example, the following general formula as a monomer component: (However, R ¹ is hydrogen or a methyl group, and R ² has 2 to 4 carbon atoms.
, R ³ is hydrogen or an alkyl group, and n is 1 or an integer of 2 or more. 1) or 2 types of (meth) acrylic acid ester monomer represented by), (meth) acrylic acid, vinylpyrrolidone, acrylamide, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, vinyl methyl ether, etc. Examples include those using the above. Moreover, the above-mentioned monomer components may be copolymerized by using (meth) acrylic acid ester, vinyl acetate, styrene and the like in a proportion of 30% by weight or less.

On the other hand, as a specific example of a (meth) acrylic acid ester monomer forming a water-soluble or water-swellable polymer, that is, a polymer obtained by polymerization is a water-soluble or water-swellable (meth) acrylic acid ester monomer. Examples thereof include the above-mentioned (meth) acrylic acid ester monomers, dimethylaminoethyl (meth) acrylate, and diethylaminoethyl (meth) acrylate.

On the other hand, specific examples of the copolymer composed of the carboxyl group-containing monomer and the (meth) acrylic acid alkyl ester in the above-mentioned carboxyl group-neutralized copolymer salt include acrylic acid, methacrylic acid, and maleic anhydride. , 10 to 40 mol% of a carboxyl group-containing monomer such as itaconic acid, butyl group, isobutyl group, isoamyl group, hexyl group, 2-ethylhexyl group, isooctyl group, isononyl group, isodecyl group, dodecyl group having 4 or more carbon atoms 90 to 60 mol% of a (meth) acrylic acid alkyl ester having an alkyl group, and other vinyl monomers such as vinyl acetate, styrene, N-vinylpyrrolidone, acrylonitrile and methacrylonitrile.
A copolymer and the like consisting of ˜20 mol% can be mentioned.

Specific examples of the hydrophilic compound represented by the general formula: R ⁴ O (R ⁵ O) _m R ⁶ include R ⁴ having 1 to 4 carbon atoms.
Alkyl group, R ⁵ is an alkylene group having 2 to 4 carbon atoms, R ⁶
Is hydrogen or an alkyl group having 1 to 4 carbon atoms or an acetyl group, and m is an integer of 1 to 6.

The hydrophilic polymer preferably used for forming the water-swellable pressure-sensitive adhesive layer in the present invention is (meth) acrylic acid or / and its derivative, and in particular, the homopolymer has a glass transition temperature of -10 ° C or lower. This is the one used as the monomer component. Incidentally, an example of the monomer component capable of forming the homopolymer is represented by the formula: CH ₂ CHCO
A caprolactone adduct of acrylic acid represented by O (C ₅ H ₁₀ COO) _x H (where x is 1 to 10),
Examples thereof include a monomer mixture contained so that the average value of x is 1 to 5.

The adhesive for forming the water-swellable adhesive layer is, for example, a water-soluble or water-swellable hydrophilic polymer,
It can be prepared as a water-based one such as a solution or dispersion containing at least a water-soluble epoxy crosslinking agent and / or a water-soluble aziridine crosslinking agent. The purpose of such an aqueous system is to obtain a pressure-sensitive adhesive containing a water-soluble cross-linking agent uniformly dispersed therein. Therefore, as the dispersion medium, water or / and a hydrophilic solvent such as alcohol or acetone can be used, and if necessary, a lipophilic solvent compatible with the hydrophilic solvent can be used in combination.

As the water-soluble epoxy cross-linking agent and the water-soluble aziridine cross-linking agent, a suitable water-soluble polyfunctional compound can be used. A water-soluble aziridine-based crosslinking agent that can be preferably used is, for example, 2,2-bishydroxymethylbutanol-
Examples include aziridine compounds such as tris (3- (1-aziridinyl) propionate).

Water-soluble epoxy crosslinking agents that can be preferably used include triglycidyl isocyanurate, sorbitol polyglycidyl ether, (poly) glycerol polyglycidyl ether, (poly) ethylene glycol diglycidyl ether, and (poly) propylene glycol diglycidyl. Examples thereof include epoxy compounds such as aliphatic glycidyl ethers such as ethers and alicyclic glycidyl ethers such as sorbitan polyglycidyl ethers.

The amount of the water-soluble epoxy cross-linking agent and / or the water-soluble aziridine cross-linking agent is 100% based on the base polymer.
It is preferably 15 parts by weight or less, and more preferably 1 to 10 parts by weight per part by weight. If the blending amount exceeds 15 parts by weight, the resulting water-swellable pressure-sensitive adhesive layer may be poor in adhesive strength (sealing property of the circuit pattern surface) and water-swelling property.

If desired, the adhesive may be mixed with known additives such as surfactants, (polymer) plasticizers and thickeners to modify the adhesive properties. ,
The additive used is preferably one containing no metal salt or the like, or nonionic one from the viewpoint of preventing alteration of the circuit pattern.

The protective member can be formed, for example, according to a method for forming an adhesive tape, such as a method in which an adhesive is applied to a support film and the adhesive is crosslinked by heating or the like. The thickness of the water-swellable pressure-sensitive adhesive layer to be formed may be appropriately determined. Generally, it is set to 5 to 100 μm.

As shown in FIG. 1, the water-swellable pressure-sensitive adhesive layer in the protective member is adhered and protected by the separator 3 or the like until it is adhered to the semiconductor wafer from the viewpoint of preventing contamination during storage or distribution. It is preferable. The separator is usually formed of a flexible thin sheet made of paper, a plastic film, a metal foil, or the like, and if necessary, surface-treated with a release agent to impart releasability.

The protective member of the present invention can be adhered to the circuit pattern surface of the semiconductor wafer in an appropriate form. When the semiconductor wafer is previously molded into a shape corresponding to the planar shape of the semiconductor wafer, the molding processing step after the bonding to the semiconductor wafer can be omitted. On the other hand, a protective member having a predetermined shape may be adhered to a carrier tape made of a long separator at predetermined intervals so that an automatic bonding apparatus can be applied.

The protective member preferably has an antistatic function in order to prevent the generation of static electricity at the time of adhesion or peeling of the protective member and the destruction of the circuit due to the electrification of the semiconductor wafer. The antistatic ability is imparted by an appropriate method such as addition of an antistatic agent or a conductive agent to the support film or the water-swellable pressure-sensitive adhesive layer, and attachment of a conductive layer composed of a charge transfer complex or a metal film to the support film. A method that can be performed and in which impurity ions that may alter the quality of the semiconductor wafer are less likely to occur is preferable. Also, since static electricity is generated when the separator is adhered or peeled off, a conductive layer may be provided on the separator to make it difficult to be charged. The conductive layer may be formed by an appropriate method.

Example 1 80 parts by weight of methoxyethyl acrylate (weight part, the same applies hereinafter), formula: CH ₂ CHCOO (C ₅ H ₁₀ COO) _x H (x
Is a caprolactone adduct of acrylic acid represented by a mean value of about 1.8 in the range of 1 to 5 (manufactured by Toagosei Kagaku:
Aronix M-5300) 20 parts, pure water 96 parts, methanol 144 parts, azobisisobutyronitrile 0.17
A solution containing a copolymer having a weight average molecular weight of 150,000, which was obtained by mixing 5 parts by a conventional method and copolymerizing it in a flask.
Parts, 5 parts by weight of polyethylene diglycidyl ether (crosslinking agent) per 100 parts by weight of the copolymer is applied to the corona-treated surface of a 100 μm thick ethylene / vinyl acetate copolymer film. 1 at 80 ℃
After heat-crosslinking for 0 minutes, a protective member having a water-swellable pressure-sensitive adhesive layer having a thickness of 20 μm was obtained.

Adhesive strength of the water-swellable pressure-sensitive adhesive layer in the protective member to the mirror wafer (180 degree peeling, peeling speed 300 mm / min, 23 ° C., 65% RH, the same applies hereinafter)
Was 70 g / 20 mm. The gel fraction of the water-swellable pressure-sensitive adhesive layer was 75%. The gel fraction was measured by peeling off the water-swellable pressure-sensitive adhesive layer on the support film and then removing methanol (2
It was immersed in (3 ° C.) for 96 hours, and calculated from the weight change before and after the immersion.

Example 2 80 parts of methoxyethyl acrylate, Aronix M-5
300: 20 parts, butyl acrylate 5 parts, pure water 96 parts,
Methanol 144 parts, azobisisobutyronitrile 0.
A protective member was obtained in the same manner as in Example 1 except that 175 parts were mixed and a copolymer having a weight average molecular weight of 200,000 was copolymerized in a flask by a conventional method. The adhesive force of the water-swellable adhesive layer to the mirror wafer was 90 g / 20 mm, and the gel fraction was 80%.

Example 3 2,2-bishydroxymethylbutanol-tris (3- (1-aziridinyl) propionate) as a cross-linking agent
A protective member was obtained in the same manner as in Example 2 except that 2 parts were used.
The adhesive force of the water-swellable adhesive layer to the mirror wafer is 70.
The gel fraction was 85% at g / 20 mm.

Comparative Example 1 80 parts of butyl acrylate, 15 parts of acrylonitrile and 5 parts of acrylic acid were copolymerized in ethyl acetate by a conventional method to prepare a solution containing an acrylic copolymer having a weight average molecular weight of 800,000. A protective member was obtained in the same manner as in Example 1 except that a solution of an acrylic pressure-sensitive adhesive containing 5 parts of a polyisocyanate compound was used as a crosslinking agent. The adhesive force of the water-swellable adhesive layer to the mirror wafer is 80 g / 20 mm, and the gel fraction is 7
It was 5%.

Comparative Example 2 A protective member was obtained in the same manner as in Example 2 except that 3 parts of zinc acetate was used as a crosslinking agent. The adhesive force of the water-swellable adhesive layer to the mirror wafer was 170 g / 20 mm, and the gel fraction was 0%.

Evaluation Test The protective members obtained in the examples and comparative examples were adhered to a mirror wafer having a diameter of 4 inches and a thickness of 0.6 mm in a clean room of class 10, and then the semiconductor wafer was subjected to back surface polishing treatment by a conventional method. The protective member was peeled off from the obtained polished wafer, and the presence or absence of infiltration of cleaning water into the wafer interface during polishing was examined. The time during which the protective member was adhered to the semiconductor wafer was 1 hour.

Next, the above-mentioned polished wafer was immersed in ultrapure water, ultrasonically cleaned (950 kHz) for 3 minutes, and then dried by a spin dryer, and the surface constituent element ratio of the protective member peeled surface was measured.

On the other hand, the protective member obtained in each of Examples and Comparative Examples was adhered to the mirror surface of a mirror wafer having a diameter of 4 inches and a thickness of 0.6 mm to obtain a polished wafer according to the above, followed by ultrasonic cleaning and drying. The number of 0.28 μm or more particle contaminants remaining on the protective member peeling surface was measured (laser surface inspection device, LS-5000, manufactured by Hitachi Electronics Engineering Co., Ltd.).

The above results are shown in Table 1.

[Table 1] * Blank: Mirror wafer surface in initial state

From Table 1, according to the protective member of the present invention, a semiconductor wafer (circuit pattern surface) which is sufficiently clear only by washing with water.
It can be seen that However, it is difficult for the protective member of Comparative Example 1 to remove contaminants only by washing with water, and the protective member of Comparative Example 2 has a gel fraction of 0% and its cross-linking is ionic bond via carboxyl group and metal salt. Since they are attracted to each other, the cross-linking may be broken by the water content, which is why the infiltration of washing water into the interface was recognized (insufficient sealing force).

In the back surface polishing treatment of the semiconductor wafer, in the case of any of the protective members obtained in the examples, water invades at the time of polishing, the circuit pattern surface is contaminated by polishing dust, and the protective member is peeled off. The wafer protection functions such as damage prevention were perfect. Further, even when the protective member was peeled and removed, it could be easily peeled without breaking the polishing wafer.

[0043]

According to the present invention, protective functions such as contamination prevention, damage / damage prevention, and peeling prevention of a wafer during processing such as back surface polishing required for a semiconductor wafer protection member, and a polished wafer are not damaged. While satisfying the smooth peeling removability, the amount of residual particle contaminants such as glue residue on the circuit pattern surface after peeling is small, and it can be sufficiently cleaned even if it is washed directly with water without prewashing with an organic solvent. Therefore, the pre-cleaning with the organic solvent can be omitted, the cleaning efficiency is excellent, and the protective member that does not corrode the circuit pattern surface can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an example.

[Explanation of symbols]

1: Support film 2: Water-swellable adhesive layer 3: Separator

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H01L 21/304 321 B 341 Z

Claims (3)

[Claims] 1. A circuit pattern surface of a semiconductor wafer, comprising a water-swellable pressure-sensitive adhesive layer cross-linked with a water-soluble epoxy crosslinking agent and / or a water-soluble aziridine crosslinking agent on a support film. Protective member for. 2. The water-swellable pressure-sensitive adhesive layer has a weight average molecular weight of 5
It consists of 1,000,000 to 3,000,000 hydrophilic polymers crosslinked with a gel fraction of 40% or more, and has an adhesive force of 50 to 300g / 20 based on 180 degree peeling to the mirror wafer.
The protective member according to claim 1, which has a size of mm. 3. A hydrophilic polymer forming a water-swellable pressure-sensitive adhesive layer is (meth) acrylic acid or / and a (meth) acrylic acid derivative forming a homopolymer having a glass transition temperature of −10 ° C. or less as a monomer component. Claim 1
Alternatively, the protective member according to item 2.