JPH07183195A - Resist peeling sheets and resist peeling off method using the sheets - Google Patents

Abstract

PURPOSE:To make it possible to enhance adherence to a resist surface and peel off the resist layer easily, and what is more, definitely by using an after- expindable base material which is expanded by heating when required as a base material of an adhesive sheet and installing a pressure sensitive adhesive layer to a single surface of the after-expandable base material CONSTITUTION:A pressure sensitive adhesive layer is installed to a single surface of an after-expandable base material. There is no particular limitation to the quality of the after-expandable layer as long as it is solid before heating and expandable during heating. More specifically, a chemical foaming agent, such as azo groups or plastic materials mixed with a heat expandable micro-capsule may be cited. The thickness of the foaming layer is not specified in particular. As a pressure sensitive adhesive which laminates layers by way of an after- expandable layer, such an adhesive is favorable, which contains non-volatile compounds which are excellent in affinity with a resist material, and what is more, have at least one unsaturated double bond in the molecules. From the viewpoint of contamination prevention, the application of curing pressure sensitive adhesive sheets is favorable.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image (resist pattern) formed of a resist that is no longer needed during the manufacture of various types of microfabricated components such as semiconductors, circuits, various printed boards, various masks, and lead frames. The present invention relates to sheets, such as a resist stripping sheet or tape, which are preferably used for stripping and removing the remaining resist), and a resist stripping and removing method using the same.

Hereinafter, the present invention will be described with reference to the example of semiconductor device manufacturing, but the present invention is not limited to the use as long as it is an article having an image made of a resist material.

[0003]

2. Description of the Related Art For example, in the manufacture of semiconductor devices, a resist material is applied onto a semiconductor substrate such as a silicon wafer and a predetermined image (resist pattern) is formed by an ordinary photo process. Using this as a mask, various processes such as ion implantation, etching, and doping are performed. After that, the unnecessary image is removed and a predetermined circuit is formed. Next, in order to form the next circuit, the cycle of applying the resist material again is repeated. Also, when circuits are formed on various substrates, unnecessary images are removed after image formation. At this time, the image of the resist material that is no longer needed is removed by using an asher (ashing means), a solvent (peeling liquid),
It is generally performed with chemicals.

[0004]

However, if the asher is used for removing the image, the work may take a long time and the impurity ions in the resist material may be implanted into the wafer. In addition, the use of solvents and chemicals has caused a problem of damaging the working environment.

In order to solve this problem, the present applicants have the following advantages when removing the unnecessary resist on the semiconductor substrate.
A resist stripping method using a pressure-sensitive adhesive sheet has been proposed (Japanese Patent Application No. 3-88053). However, there are some cases where the adhesiveness of the pressure-sensitive adhesive sheet to the resist surface is low, and there are some places, which causes a problem that the releasability of the resist decreases. Therefore, it may be possible to improve the wettability of the pressure-sensitive adhesive to be used on the resist surface (for example, JP-A-4-345015), but the adhesiveness after curing is reduced and the cohesive force of the adhesive is reduced. Then, there was a problem that the adhesive residue was likely to remain.

[0006]

Means for Solving the Problems As a result of intensive studies to solve this problem, the present inventors have found that by using a post-foaming base material as the base material of the adhesive sheet, the adhesion to the resist surface is improved. It has been found that the resist can be improved and the resist can be removed easily and surely, and the present invention has been completed.

That is, the present invention provides resist stripping sheets in which a pressure-sensitive adhesive layer is provided on one surface of a post-foaming base material. Furthermore, the present invention is to adhere the resist stripping sheet onto a resist on an article having a resist pattern, heat-foam a post-expandable base material of the resist stripping sheet, and then to form the sheet. There is provided a method for removing and removing a resist, wherein the method and the resist are integrally removed.

[0008]

[Structure / Function of the Invention] The resist stripping sheets of the present invention comprise a pressure-sensitive adhesive layer provided on one surface of a post-foaming substrate. Here, the post-foaming base material is a material which is not foamed before use and is foamed by a heating means when necessary. In the present invention, for example, resist stripping sheets in which a pressure-sensitive adhesive layer is provided on one surface of a substrate via a post-foaming layer are preferably used.

The substrate is not particularly limited as long as it has heat resistance during heat foaming, but in the present invention,
For example, polyester, polyamide, polyvinyl butyral, polymethylpentene, heat-resistant plastic film such as polyphenylene sulfide, paper,
Cloth, or a composite film of these, and the like,
Particularly, a plastic film such as polyester is preferably used. The thickness is usually about 10 to 200 μm.
A base material of a certain degree is used, and in particular, when the adhesive described below is cured by light irradiation, a material that transmits light such as ultraviolet rays is selected and used.

The post-foaming layer provided on one surface of the above-mentioned substrate is not particularly limited as long as it is not foamed before heating and foams at the time of heating. For example, a chemical foaming agent such as an azo compound or heat expansion agent. Examples of the plastic material include mixed microcapsules. The plastic material is not particularly limited, for example, polyolefin,
Examples thereof include polystyrene, natural rubber, synthetic rubber, acrylic polymers, silicone polymers, vinyl acetate copolymers and saponified products thereof.

The foaming with a foaming agent is preferably 10 to 3
A foaming ratio of 00%, particularly preferably 30 to 100% is good for improving the releasability. If it is larger than this range, cohesive failure of the pressure-sensitive adhesive layer is likely to occur, and the releasability may be rather deteriorated. The thickness of the foam layer is not particularly limited as long as it does not cause cohesive failure after foaming, and is generally 5 to 100 μm, preferably 15 to 50.
μm.

The pressure-sensitive adhesive layer laminated via the post-foaming layer has a good affinity for the pressure-sensitive adhesive polymer with the resist material and has 1 unsaturated double bond in the molecule.
A pressure sensitive adhesive containing at least one nonvolatile compound is preferably used. From the viewpoint of preventing contamination of the semiconductor substrate, it is particularly preferable to use a curable pressure-sensitive adhesive sheet described below.

Such a curable pressure-sensitive adhesive comprises a pressure-sensitive adhesive polymer containing a non-volatile compound having a good affinity for a resist material and having at least one unsaturated double bond in the molecule. Is preferred.

As the above-mentioned pressure-sensitive adhesive polymer, any of various known polymers applied to general pressure-sensitive adhesives can be used, and particularly preferable polymers are alkyl acrylate and / or methacrylic acid. An acrylic polymer having an alkyl ester as a main monomer can be used.

This acrylic polymer is a main monomer described above, that is, an ester of acrylic acid or methacrylic acid with an alcohol having a carbon number of usually 12 or less, a monomer having a carboxyl group or a hydroxyl group if necessary, and other modifications. It can be obtained by polymerizing these using a monomer for use by a conventional method such as solution polymerization, emulsion polymerization, suspension polymerization and bulk polymerization.

Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, maleic acid,
Itaconic acid or the like is used, and as the hydroxyl group-containing monomer, for example, hydroxyethyl acrylate, hydroxypropyl acrylate or the like is used.

As the above-mentioned other modifying monomers, vinyl acetate, vinyl propionate, styrene, acrylonitrile, acrylamide, couglycidyl methacrylate and the like are used. The amount of these modifying monomers used is preferably 50% by weight or less in the total amount with the main monomer.

The acrylic polymer composed of such monomers has a weight average molecular weight of usually 30.
It is preferably from 10,000 to 2,000,000. If the molecular weight is too low, the viscosity will be low when the non-volatile compound described below is blended therein, and problems such as flowing during storage are likely to occur, and if it is too high, handling problems are likely to occur. Further, the acrylic polymer preferably has a glass transition point of 250 ° K or lower in consideration of workability at the time of image removal. If it is higher than this, it tends to be too hard after curing and the peeling tends to be heavy. However, it does not try to eliminate all the use of acrylic polymers having such a high glass transition point,
Of course, it can be used in some cases.

In the present invention, the pressure-sensitive adhesive polymer contains a non-volatile compound having a good affinity with a resist agent and having at least one unsaturated double bond in the molecule. An adhesive sheet made of a pressure sensitive adhesive is preferably used. Here, having a good affinity with the resist material means that the phenomenon of dissolving, swelling or destroying the resist material is remarkable, and also includes the phenomenon of migration or diffusion into the resist material. As a guide for this, the resist material is sufficiently dried and the solvent is dipped in the non-volatile compound, and the resist material is dissolved, swelled or destroyed when stored at 130 ° C. for 24 hours. Further, that the compound is non-volatile means that it is not easily volatilized in the step of coating and drying the adhesive.

Such a non-volatile compound has a function of bonding adhesive sheets onto a semiconductor substrate on which a resist film image is present, the resist material and the adhesive are integrated by the action of this compound, and then cured. . Therefore, this non-volatile compound has one or more unsaturated double bonds that can be cured by heat or light in the molecule, and has good affinity with the resist material (which can be defined as above). It is also required that the compatibility with the pressure-sensitive adhesive polymer is good and that the polymer does not flow out during storage.

Examples of such a non-volatile compound include phenoxy polyethylene glycol (meth) acrylate, ε-caprolactone (meth) acrylate, polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate and trimethylolpropane tri. (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate, oligoester (meth) acrylate, and the like. Among these, the type of pressure-sensitive adhesive polymer to be used. One or two or more of them can be appropriately selected and used depending on the target resist material.

The amount of the non-volatile compound used is usually 5 to 20 with respect to 100 parts by weight of the pressure-sensitive adhesive polymer.
The amount is 0 parts by weight, preferably 10 to 100 parts by weight. If the amount used is too small, the peeling effect of the resist material may not be sufficient, and if it is too large, the adhesive may flow out during storage, which is not preferable.

In the above-mentioned curable pressure-sensitive adhesive of the present invention, it is preferable that the pressure-sensitive adhesive polymer is crosslinked to enhance cohesive force in terms of workability when it is attached to a semiconductor substrate. For example, an acrylic polymer obtained by copolymerizing a carboxyl group- or hydroxyl group-containing monomer as a pressure-sensitive adhesive polymer is used, and a polyfunctional compound that reacts with the functional group of the polymer, such as polyisocyanate, polyepoxy, various metal salts, By containing a chelate compound or the like in the adhesive, the above reaction can be promoted in the step of forming a sheet or the like to crosslink the polymer.

The amount of the polyfunctional compound used is usually 20 parts by weight or less based on 100 parts by weight of the pressure-sensitive adhesive polymer. Within this range, the higher the molecular weight of the polymer, the lower the molecular weight of the polymer. , May be selected as appropriate.
If the amount of the polyfunctional compound used is too large, the adhesive strength will decrease, which is not preferable.

The curable pressure-sensitive adhesive may also contain a filler such as finely divided silica for the same purpose as the use of the above polyfunctional compound. Further, various additives such as a tackifier, a colorant and an anti-aging agent may be contained if necessary. The amount of these used may be in the usual range.

A polymerization initiator suitable for the curing means can be added to the curable pressure-sensitive adhesive which can contain such various components. For example, in the case of heat curing, benzoyl peroxide, a thermal polymerization initiator such as azobisisobutyronitrile that generates radicals by heating is used, and in the case of photocuring such as ultraviolet light, benzoin, benzoin ethyl ether, A photopolymerization initiator that generates radicals by light irradiation such as dibenzyl is used. These polymerization initiators are usually used in the range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the pressure-sensitive adhesive polymer.

The curable pressure-sensitive adhesive of the present invention thus constructed has an initial elastic modulus, that is, an elastic modulus before curing of usually about 0.5 to 50 g / mm ² , and an elastic modulus after curing. It is desirable that the rate is adjusted to about 3 to 400 g / mm ² . This is because when the elastic modulus is adjusted to such a range, favorable results can be obtained for both the pressure-sensitive adhesive property before curing and the resist releasability after curing. The elastic modulus can be adjusted by appropriately selecting the type of pressure-sensitive adhesive polymer, the amount of various non-volatile compounds added to it, the amount of other compounding components, the degree of crosslinking with a polyfunctional compound, the curing conditions, and the like. It can be done by

The above-mentioned elastic modulus was determined by applying a stress-strain to the adhesive having a cross-sectional area of 5 mm ² under a temperature of 23 ± 2 ° C. at a pulling speed of 50 mm / min with a marked line distance of 10 mm. It means a value measured by a method of obtaining a curve and obtaining it from an initial slope.

Such a curable pressure-sensitive adhesive is applied on the above-mentioned substrate so that the thickness after drying becomes about 10 to 180 μm, and the resist stripping sheets of the present invention can be obtained. it can.

In the resist stripping method of the present invention, sheets comprising a post-foaming base material and a pressure-sensitive adhesive layer are attached to a resist film image on a preferably heated semiconductor substrate. The post-foamable base material is foamed by the heat, and the adhesiveness with the resist is improved. Then, by peeling off the sheets, the resist can be satisfactorily removed from the semiconductor substrate together with the sheets.

The heating method is not particularly limited, and various methods such as hot plate, oven, warm air, infrared ray, microwave, electromagnetic induction method can be used. Among these, hot plates, warm air, ovens and the like are preferable because they are relatively easy to use and can be easily introduced into the equipment.

In the present invention, after the resist material and this adhesive are integrated, a predetermined curing treatment such as heating or light irradiation may be performed. At this time, when the heat effect on the semiconductor substrate is taken into consideration, the curing treatment by light irradiation is particularly suitable, and the irradiation amount of ultraviolet rays is usually in the range of 300 to 3000 mj / cm ² .

By this curing treatment, the adhesive is cured in the state of being integrated with the resist material, and the elastic modulus thereof is remarkably increased as described above, and accordingly, the adhesive force between the resist film image and the semiconductor substrate is increased. Greatly reduced. As a result, by peeling off the adhesive sheets after the curing, the resist film image on the substrate is integrated with the adhesive sheets,
Can be removed easily and completely.

[0034]

As described above, according to the present invention, for example, the resist on the semiconductor substrate can be removed very easily and surely, and the impurity ions in the resist material are injected into the semiconductor substrate. There is an effect that it can be reduced.

[0035]

EXAMPLES The present invention will be described below based on examples. In addition, "parts" means "parts by weight".

Reference Example A surface of a silicon wafer (semiconductor substrate) is coated with a resist material composed of cresol novolac resin, naphthoquinone diazide sulfonic acid ester of polyhydroxy compound and ethyl lactate, heated, exposed and developed to form a resist film image. Was formed on the entire surface, then As ⁺ ions were implanted over the entire surface at a high concentration with an acceleration energy of 80 keV and a dose amount of 1 × 10 ¹⁶ ions / cm ² .

Example 1 [Preparation of Post-Expandable Substrate] 100 parts of a polymer having a weight average molecular weight of 800,000 consisting of 60 parts of butyl acrylate, 30 parts of 2-ethylhexyl acrylate and 10 parts of acrylic acid is used as a microcapsule type foam. A mixture of 10 parts of an agent (manufactured by Matsumoto Yushi Co., Ltd., trade name F30D) was provided on a polyester substrate (38 μm) so that the thickness after coating and drying was 15 μm, and a post-foaming substrate was produced. .

[Production of Pressure Sensitive Adhesive] A monomer mixture consisting of 80 parts of n-butyl acrylate, 15 parts of ethyl acrylate and 5 parts of acrylic acid was added to 150 parts of ethyl acetate and 0.1 part of azobisisobutyronitrile. Was subjected to solution polymerization for 12 hours at 60 ° C. in a nitrogen stream to obtain an acrylic polymer solution having a weight average molecular weight of 560,000 and a glass transition point of 231 ° K. To 250 parts of this acrylic polymer solution, urethane acrylate 100 was added as a non-volatile compound.
Parts, 3 parts of diphenylmethane diisocyanate as a polyfunctional compound, and 3 parts of benzyl methyl ketal as a polymerization initiator were uniformly mixed to obtain a curable pressure-sensitive adhesive solution.

[Preparation of Resist Stripping Sheet] Next,
The curable pressure-sensitive adhesive solution was applied onto the post-foamable substrate so that the thickness after drying was 35 μm, and 70
The adhesive sheet for resist stripping of the present invention was produced by drying at 20 ° C. for 20 minutes.

The obtained adhesive sheet was adhered to the entire surface of the resist pattern of the above reference example by pressure bonding on a heating substrate at 120 ° C., and ultraviolet rays of 1000 mJ were applied by a high pressure mercury lamp.
The adhesive sheet was cured by irradiation at a dose of / cm ² .
After that, when the adhesive sheet was peeled off, the resist film image was peeled off together with the adhesive sheet. In addition,
The surface of the silicon wafer was observed with a fluorescence microscope, but no resist material was observed.

Example 2 [Preparation of Post-Expandable Substrate] Ethylene-propylene copolymer was mixed with 30 parts of azodicarbosoamide as a foaming agent and 5 parts of urea compound as an auxiliary agent, and a paper base was formed by a pressing method. It was laminated with the material to form a sheet (150 μm). [Preparation of Pressure Sensitive Adhesive] A monomer mixture consisting of 60 parts of 2-ethylhexyl acrylate, 30 parts of butyl acrylate, 5 parts of vinyl acetate and 5 parts of acrylic acid was polymerized in the same manner as in Example 1 to obtain a weight average molecular weight. Was obtained, and an acrylic polymer solution having a glass transition point of 217 ° K was obtained. To 250 parts of this acrylic polymer solution, 100 parts of oligoester acrylate as a non-volatile compound, 3 parts of tolylene diisocyanate as a polyfunctional compound, and 5 parts of benzyl methyl ketal as a polymerization initiator were uniformly mixed to give a curable pressure-sensitive composition. An adhesive solution was obtained. Next, the curable pressure-sensitive adhesive solution was applied onto the post-foamable substrate so that the thickness after drying was 45 μm, and dried at 90 ° C. for 5 minutes to remove the resist of the present invention. An adhesive sheet for use was produced.

The obtained adhesive sheet was subjected to a resist pattern peeling removal treatment in the same manner as in Example 1.
The same result as in Example 1 was obtained.

Comparative Example 1 When a peeling removal treatment was carried out in the same manner as in Example 1 except that a usual polyester film (50 μm) was used as the substrate, only the adhesive sheet was peeled off, and the resist was placed on the silicon wafer. It remained all over.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryo Namikawa 1-2-1, Shimohozumi, Ibaraki City, Osaka Prefecture Nitto Denko Corporation

Claims (4)

[Claims] 1. A sheet for resist peeling, comprising a pressure-sensitive adhesive layer provided on one surface of a post-foaming base material. 2. The resist stripping sheet according to claim 1, wherein the post-foaming layer contains a heat-expandable microcapsule type foaming agent. 3. The pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive polymer containing a non-volatile compound having good affinity with a resist material and having at least one unsaturated double bond in the molecule. The resist stripping sheet according to claim 1, wherein: 4. The resist stripping sheet according to any one of claims 1 to 3 is pasted onto a resist on an article having a resist pattern, and the post-foaming base material of the resist stripping sheet is heated and foamed. And then removing the sheet and the resist integrally with each other.