JP2001055546A - Lowly staining adhesive sheet or the like and removal of resist material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sheet or the like being useful for e.g. the removal of a resist material or foreign matter and leaving no organic contaminant derived from the sheet or the like on the surface of an article such as a substrate by forming a layer of an adhesive based on a pressure-sensitive adhesive polymer substantially free from an oligomeric low-molecular-weight component on a filmy support. SOLUTION: The pressure-sensitive adhesive polymer is desirably one that is subjected reprecipitation from a poor solvent and therefore is substantially free from a low-molecular-weight component having a molecular weight of at most 5,000 and is more desirably one that has a polydispersity index (weight- average molecular weight/number-average molecular weight) of at most 10. Further, the polymer is desirably an acrylic polymer chiefly made from an alkyl (meth)acrylate. It is desirable that the adhesive layer is a layer of a curable, desirably, photocurable adhesive containing a polymerizable compound having at least one double bond in the molecule and a polymerization initiator, desirably, a photopolymerization initiator in addition to the above polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly relates to re-peeling, which is used in the manufacture of various industrial members, in particular, microfabricated parts such as semiconductors, circuits, various printed boards, various masks, and lead frames. The present invention relates to a technique for reducing contamination of adherends for use with adhesive sheets.

[0002]

2. Description of the Related Art For example, in semiconductor device manufacturing,
A resist material is applied on a silicon wafer, and a predetermined resist pattern (resist film image) is formed by a normal photo process. After etching using this as a mask, unnecessary resist material is removed, and a predetermined circuit is formed. Is formed. In order to form the next circuit, a cycle of applying the resist material again is repeatedly performed. Also, when circuits are formed on various substrates, unnecessary resist material is removed after the formation of the resist pattern.

Generally, unnecessary resist material is removed by using an asher (ashing means), a solvent, a chemical, or the like. However, if an asher is used to remove the resist material, it may take a long time to work, impurities in the resist material may be injected into the wafer, and the semiconductor substrate may be damaged. Further, the method using a solvent or a chemical has a problem that the working environment is harmed.

For this reason, recently, an adhesive sheet having an adhesive layer containing a pressure-sensitive adhesive polymer as a main component on a film base material is used, and this is adhered to the upper surface of a resist pattern. After performing a specific treatment such as heat treatment, a method has been proposed in which the adhesive sheets are peeled off and the resist material is peeled off from the substrate integrally with the adhesive sheets. However, such a method using an adhesive sheet may cause a large amount of organic contaminants derived from the adhesive sheet to remain on the substrate after the resist material is peeled off. In order to remove the above contaminants after the stripping operation, the above method was not necessarily a simple removal method.

The above example relates to a method of removing a resist material.
As a means for removing foreign substances (dust) present on the substrate surface, the same adhesive sheet as described above is used, and the foreign substances are often attached to and removed therefrom. Later, a large amount of organic contaminants derived from the adhesive sheet may remain on the substrate, which has the same problem as described above. In addition, when the adhesive sheets are used for re-peeling other than the above, for example, when used for surface protection of metal plates or the like or coating masking, when the purpose of surface protection or masking is achieved, peeling is performed. In addition, a large amount of organic contaminants derived from adhesive sheets may remain on the surface of a metal plate or the like, and the same problem as described above still remains.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has been described in view of the fact that, when an adhesive sheet is used for removing a resist material or a foreign substance, protecting a surface, masking, and other re-peeling, To provide low-contamination adhesive sheets that can prevent organic contaminants derived from adhesive sheets from remaining on the surface of articles such as substrates, and particularly to use these adhesive sheets. It is an object of the present invention to provide a method for removing a resist material.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies in order to achieve the above-mentioned object. As a result, first, the organic contaminant remains on the adherend surface after peeling off the adhesive sheets. Pressure-sensitive adhesive polymer, which is the main component contained in the agent layer,
For example, it is caused by acrylic polymer.
The pressure-sensitive adhesive polymer has a wide molecular weight distribution range, and particularly contains a large number of oligomer-like low molecular weight substances, so that the pressure-sensitive adhesive is liable to break or agglomerate, which is a problem for adherends. It has been determined that it is a major cause of organic pollution.

That is, in an adhesive sheet in which an adhesive layer containing a pressure-sensitive adhesive polymer as a main component is provided on a film substrate, at least at the time of peeling off the sheets, an oligomer-like low molecular weight substance is formed in the adhesive layer. It has been found that if not substantially contained, it is possible to prevent organic contamination of the adherend without causing breakage or cohesive failure as a pressure-sensitive adhesive.

The present inventors have further studied based on this finding, and carried out reprecipitation treatment with a poor solvent on the above pressure-sensitive adhesive polymer to reduce the content of the low molecular weight polymer. The present inventors have found that organic contamination of an adherend can be greatly reduced when the molecular weight is reduced and the molecular weight distribution width is reduced, and the present invention has been completed.

That is, the present invention relates to an adhesive sheet comprising a film substrate provided with an adhesive layer containing a pressure-sensitive adhesive polymer as a main component, wherein the pressure-sensitive adhesive polymer is an oligomeric low molecular weight polymer. Low-contamination adhesive sheets characterized in that they are substantially free from (Claim 1)
In particular, the low-contamination adhesive sheets (Claim 2), in which the pressure-sensitive adhesive polymer does not substantially contain a low-molecular-weight substance having a molecular weight of 5,000 or less, and the pressure-sensitive adhesive polymer, The low-staining adhesive sheets having a molecular weight dispersity (weight average molecular weight / number average molecular weight) of 10 or less (Claim 3), and the pressure-sensitive adhesive polymer are subjected to reprecipitation treatment with a poor solvent. Said low-contamination adhesive sheet (claim 4), further removing a resist material and foreign matter;
The present invention relates to the low-contamination adhesive sheets for claiming surface protection, masking and other re-peeling (claim 9).

The present invention also relates to a more specific embodiment of such low-staining adhesive sheets, in which the pressure-sensitive adhesive polymer comprises an alkyl (meth) acrylate as a main monomer.
Low-contamination adhesive sheets (claim 5), which are acryl-based polymers, and a polymerizable adhesive layer having one or more unsaturated double bonds in the molecule in addition to the pressure-sensitive adhesive polymer A low-staining adhesive sheet which is a curable adhesive layer containing a compound and a polymerization initiator (Claim 6), wherein the polymerization initiator is a photopolymerization initiator, and the adhesive layer is a photopolymerization initiator. Curable low-staining adhesive sheets (Claim 7), and a low-staining adhesive in which the adhesive layer contains a polyfunctional compound for crosslinking the pressure-sensitive adhesive polymer in addition to the pressure-sensitive adhesive polymer. Sheets (claim 8) can be provided.

Further, the present invention provides a method for removing a resist material using the low-contamination adhesive sheet having the specific structure as described above.
The low-contamination adhesive sheets having the above-mentioned constitutions are adhered, and when the low-contamination adhesive sheets are of a hardening type, they are cured and then peeled off, so that the resist material can be removed from the article. And removing the resist material integrally with the low-contamination adhesive sheets. (Claim 10)
It is related to.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION As a film substrate used in the present invention, a plastic film made of polyethylene, polypropylene, polyethylene terephthalate, acetyl cellulose or the like and having a thickness of usually about 10 to 100 .mu.m is preferable. When the adhesive layer provided on the film substrate is of a photo-curing type, it is desirable to select and use a plastic film that transmits light such as ultraviolet rays.

In the present invention, an adhesive layer having a thickness of usually 10 to 180 μm is provided on such a film base material to obtain an adhesive sheet such as a sheet or a tape. Here, the adhesive layer contains a pressure-sensitive adhesive polymer as a main component, and the pressure-sensitive adhesive polymer includes various known polymers applied to a general pressure-sensitive adhesive. However, it is particularly preferable to use an acrylic polymer having an alkyl (meth) acrylate as a main monomer.

[0015] Such an acrylic polymer is composed of an alkyl (meth) acrylate, that is, acrylic acid or methacrylic acid and an alcohol having usually 12 or less carbon atoms.
Esters (e.g., n-butyl acrylate, 2-ethylhexyl acrylate, etc.) as the main monomer,
If necessary, a monomer containing a carboxyl group or a hydroxyl group
(Eg, acrylic acid, methacrylic acid, hydroxyethyl acrylate, etc.) and other modifying monomers (eg, vinyl acetate, vinyl propionate, styrene,
Acrylonitrile, acrylamide, glycidyl acrylate, etc.) can be used to polymerize these monomers by a conventional method such as solution polymerization, emulsion polymerization, suspension polymerization, or bulk polymerization.

The acrylic polymer synthesized by such a method generally has a wide molecular weight distribution range, and is a mixture of oligomers having a molecular weight of several thousand or less to several millions. The following oligomers are several weight% to 10
% By weight. In the present invention, a pressure-sensitive adhesive polymer such as an acrylic polymer is subjected to a reprecipitation treatment with a poor solvent to have a molecular weight of 5,
It is characterized in that substantially no low-molecular-weight substance of 000 or less, preferably 10,000 or less is substantially not contained. The polymer has a molecular weight dispersity (weight average molecular weight / number average molecular weight) of 10 or less, preferably 8 or less;
More preferably, it is better to be 5 or less (usually up to 2).

In the above reprecipitation treatment, alcohol-based solvents such as methanol, ethanol, isopropyl alcohol, etc. may be used as poor solvents, and in acrylic polymers, as solvents having low solubility for this polymer. After dissolving the above polymer in an aliphatic hydrocarbon solvent such as hexane or petroleum ether, the polymer is left to stand at room temperature or low temperature to reprecipitate the polymer, and the precipitated polymer is dried and recovered. Is a processing method. The low molecular weight in the polymer is not limited to the reprecipitation treatment, and may be reduced by various known methods. However, the pressure-sensitive adhesive polymer obtained by the reprecipitation treatment hardly contains a low molecular weight compound having a molecular weight of 5,000 or less, and can be used as a polymer particularly suitable for the present invention.

In the present invention, the molecular weight of 5,
By using a pressure-sensitive adhesive polymer substantially free of low-molecular-weight substances of 000 or less, and by using the above-mentioned polymer having a narrow molecular weight distribution width such that the degree of dispersion of the molecular weight is 10 or less, Adhesive sheets made by providing an adhesive layer containing a polymer as a main component on a film base material are suitable for re-peeling without leaving organic contaminants on the adherend surface unlike conventional products. They have been found to be low-contamination adhesive sheets.

The pressure-sensitive adhesive polymer used in the present invention preferably has a weight average molecular weight in the range of 500,000 to 5,000,000 and a number average molecular weight in the range of 300,000 to 3,000,000.
The average molecular weight and the degree of dispersion of the molecular weight are determined by GPC.
It is a value in terms of polystyrene by a (gel permeation chromatography) method. In addition, low molecular weight compounds having a molecular weight of 5,000 or less in the polymer are obtained from the molecular weight distribution curve.
Its presence can be detected.

As the adhesive layer in the present invention, various types having the above-mentioned specific pressure-sensitive adhesive polymer as a main component can be used. It is preferable that the curable adhesive layer comprises a polymerizable compound having at least one double bond and a polymerization initiator, and in particular, the polymerization initiator is a photopolymerization initiator, and the adhesive layer is Light-curing type is desirable.

As the polymerizable compound, one or more unsaturated double bonds which can be cured by application of light or heat energy are used.
Phenoxy polyethylene glycol (meth) acrylate, ε-caprolactone (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate -Trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, urethane (meth) acrylate
Acrylate, epoxy (meth) acrylate, oligoester (meth) acrylate, etc.
Species or two or more species are used. The amount of the polymerizable compound to be used is 10 to 4 per 100 parts by weight of the pressure-sensitive adhesive polymer.
The amount is preferably 00 parts by weight, preferably 50 to 300 parts by weight.

As the above-mentioned polymerization initiator, benzyl dimethyl ketal, benzoin, benzoin ethyl ether, dibenzyl and the like are used as photopolymerization initiators which generate radicals upon irradiation with light. Further, as a polymerization initiator that generates a radical by the application of thermal energy,
Organic peroxides such as benzoyl peroxide and azo initiators such as 2,2'-azobisisobutyronitrile are used. The amount of the polymerization initiator is 0.1 to 10 parts by weight, preferably 1 to 100 parts by weight of the pressure-sensitive adhesive polymer.
It is preferred that the amount be up to 5 parts by weight.

In addition, such various types of adhesive layers are provided with a polyfunctional compound for crosslinking the pressure-sensitive adhesive polymer, for example, a polyisocyanate compound, in order to improve cohesive strength. , A polyfunctional epoxy compound, an aziridine compound and the like. Furthermore, as long as the effects of the present invention are not impaired, various known additives such as a tackifier, a colorant, and an antioxidant can be included.

The low-contamination adhesive sheets of the present invention constructed as described above are used for manufacturing various industrial members, particularly, finely processed parts such as semiconductors, circuits, various printed boards, various masks, and lead frames. In the above method, it can be used as a means for removing a resist material or a foreign substance, and in various other applications for re-peeling, and can contribute to low contamination of an adherend. Furthermore, it is widely used in various applications where the adhesive sheet is peeled off at the end of use or at the end of use, for example, for surface protection, masking, and other re-peeling, taking advantage of the feature of low contamination. can do.

In the present invention, a method of removing a resist material can be provided as an invention of a method of using the above-mentioned low-contamination adhesive sheet. That is, the removing method is to apply the above-mentioned low-contamination adhesive sheets to a product on which a resist pattern is present by heating and / or pressurizing as necessary, thereby forming an adhesive layer and a resist material. When the adhesive sheet is of a curable type, it is cured.
Irradiating with an irradiation amount of up to 3,000 mJ / cm ² , photo-curing, and peeling operation to remove the resist material from the article integrally with the low-contamination adhesive sheet. It was done.

According to such a removing method, the work is easier, the working environment is impaired, and impurities in the resist material are reduced as compared with a conventional method using an asher (ashing means), a solvent, a chemical, or the like. There is no need to worry about injection into the wafer or damaging the semiconductor substrate, and no organic contaminants derived from adhesive sheets remain on the surface of the above-mentioned articles. The operation of removing the above contaminants after the operation is unnecessary, and the resist material can be removed very easily.

[0027]

Next, an embodiment of the present invention will be described in more detail. In the following, Mw indicates the weight average molecular weight of the acrylic polymer, Mn indicates the number average molecular weight of the acrylic polymer, and Mw / Mn indicates the degree of dispersion of the molecular weight of the acrylic polymer. In the method of removing a resist material shown in the following examples, a resist film image A (resist pattern
(N) is formed on a semiconductor wafer by the method of Reference Example 1 below.

REFERENCE EXAMPLE 1 A resist material comprising PHS (polyhydroxystyrene) and an acid generator was applied to the surface of a silicon wafer (8-inch semiconductor substrate) having an oxide film formed on the surface, and heated, exposed and developed. After forming a pattern, the oxide film was removed by dry etching using the resist pattern as a mask. The resist pattern on the silicon wafer thus treated was used as a resist film image A.

Example 1 Acrylic polymer A (Mw: 2.8 million; copolymer) composed of a copolymer of 2-ethylhexyl acrylate / methyl acrylate / acrylic acid = 30/70/10 (weight ratio) synthesized by a conventional method 1000 g of a 27% by weight toluene solution of Mw / Mn 22) was mixed with 70 kg of methanol and stirred for 15 minutes at room temperature. After the stirring was stopped, the mixture was allowed to stand for 15 minutes, and then the precipitate was taken out and the solvent was dried.
Of acrylic polymer B (yield 70% by weight). The acrylic polymer B thus subjected to the reprecipitation treatment with the poor solvent has a Mw of 3.8 million,
Mw / Mn was 3.0, and it was found from the molecular weight distribution curve that no low-molecular-weight compound having a molecular weight of 50,000 or less was contained at all.

100 g of the acrylic polymer B, 50 g of a diacrylate of polyethylene glycol 600 [“NK ester A-600” manufactured by Shin-Nakamura Chemical Co., Ltd.], and dimethacrylate of polyethylene glycol 200 [Shin Nakamura A solution of 50 g of "NK Ester 4G" manufactured by Chemical Co., Ltd., 3 g of a polyisocyanate compound and 3 g of benzyldimethylketal was prepared. This adhesive solution is applied on a film substrate made of a polyester film having a thickness of 50 μm, and dried in a drying oven at 70 ° C. and 130 ° C. for 3 minutes, respectively. To form a low-contamination adhesive sheet.

Next, the above-mentioned low-contamination adhesive sheet is adhered to the resist film image A on the silicon wafer under pressure by a pressure roll under heating, and then ultraviolet rays are irradiated at 1,000 mJ by a high-pressure mercury lamp. / Cm ² to cure the adhesive sheet. Thereafter, the adhesive sheet and the resist film image A were integrally peeled off, and the image A was removed from the silicon wafer. By microscopic observation, all the resist material on the silicon wafer was removed, and no organic contaminants derived from the adhesive layer were confirmed.

Example 2 100 g of the acrylic polymer B obtained in Example 1, 100 g of a diacrylate of polyethylene glycol 600 [“NK ester A-600” manufactured by Shin-Nakamura Chemical Co., Ltd.], and 3 g of a polyisocyanate compound , Polyfunctional epoxy compound 2g
And 3 g of benzylmethylketal in toluene. A low-staining adhesive sheet was prepared in the same manner as in Example 1 except that this adhesive solution was used. Using this adhesive sheet, the resist film image A was peeled off in the same manner as in Example 1. By microscopic observation, all the resist material on the silicon wafer has been removed,
Organic contaminants derived from the adhesive layer were not observed.

Comparative Example 1 An adhesive solution was prepared in the same manner as in Example 1 except that 100 g of the acrylic polymer B was replaced with 100 g of the acrylic polymer A before being subjected to reprecipitation treatment with a poor solvent. By using this, an adhesive sheet was produced in the same manner as in Example 1.
Was made. Using this adhesive sheet, the resist film image A was peeled off in the same manner as in Example 1. Microscopic observation showed that most of the resist material on the silicon wafer had been removed, but that organic contaminants derived from the adhesive layer had remained.

[0034]

As described above, in the present invention, the use of a pressure-sensitive adhesive polymer having a reduced content of low-molecular-weight compounds by, for example, performing reprecipitation treatment with a poor solvent is used. By ensuring that the pressure-sensitive adhesive polymer is substantially free of oligomeric low molecular weights,
Providing low-contamination adhesive sheets that do not leave organic contaminants on the surface of articles such as substrates to be adhered, and are useful for removing resist materials and foreign substances, protecting surfaces, masking, and other re-peeling. it can. In addition, by using the low-staining adhesive sheets, it is possible to provide a method of removing a resist material which can easily remove and remove a resist material on an article.

Claims (10)

[Claims] 1. An adhesive sheet comprising a film substrate provided with an adhesive layer containing a pressure-sensitive adhesive polymer as a main component, wherein the pressure-sensitive adhesive polymer is substantially an oligomeric low molecular weight substance. Low-contamination adhesive sheets characterized in that they are not contained in the adhesive sheet. 2. The pressure-sensitive adhesive polymer has a molecular weight of 5,0.
2. The low-contamination adhesive sheet according to claim 1, wherein the low-molecular weight substance having a molecular weight of 00 or less is not substantially contained. 3. The low-contamination adhesive sheet according to claim 2, wherein the pressure-sensitive adhesive polymer has a molecular weight dispersity (weight average molecular weight / number average molecular weight) of 10 or less. 4. The low-contamination adhesive sheet according to claim 2, wherein the pressure-sensitive adhesive polymer has been subjected to reprecipitation treatment with a poor solvent. 5. The low-contamination adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive polymer is an acrylic polymer having an alkyl (meth) acrylate as a main monomer. Kind. 6. A curable adhesive layer comprising, in addition to a pressure-sensitive adhesive polymer, a polymerizable compound having at least one unsaturated double bond in a molecule and a polymerization initiator. The low-contamination adhesive sheet according to any one of claims 1 to 5,
Kind. 7. The low-contamination adhesive sheet according to claim 6, wherein the polymerization initiator is a photopolymerization initiator and the adhesive layer is a photocurable type. 8. The low-contamination adhesive system according to claim 1, wherein the adhesive layer contains a polyfunctional compound for crosslinking the adhesive layer in addition to the pressure-sensitive adhesive polymer. -Guts. 9. The low-contamination adhesive sheet according to claim 1, which is used for removing a resist material or a foreign substance, protecting a surface, masking, and other re-peeling. 10. The low-contamination adhesive sheet according to any one of claims 1 to 8, on an article having a resist pattern.
When the low-contamination adhesive sheet is of a curable type, it is cured and then peeled off to remove the resist material from the article onto the low-contamination adhesive sheet. A method for removing a resist material, comprising: removing the resist material integrally with the resist material.