JPH09311468A - Adhesive sheet for removing resist and method for removing resist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To peel and remove an unnecessary resist film image on an article with an adhesive sheet, to suppress the sticking of harmful metals derived from the sheet on the article and to eliminate harmful effects on the electrical characteristics of the article such as a semiconductor wafer. SOLUTION: An adhesive sheet is composed of a film substrate and an adhesive layer formed on the substrate or a separator is further stuck on the surface of the adhesive layer and a trapping agent capable of bonding to harmful metals in the constituent members is incorporated into the adhesive layer. The resultant adhesive sheet for removing a resist is stuck on an article on which a resist film image exists after the separator is peeled when the sheet has the separator, and the sheet, together with the resist material, is peeled to remove the resist material on the article. When the sheet is a curable sheet, it is cured before the peeling.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention eliminates unnecessary resist film images (resist patterns) in the production of microfabricated parts such as semiconductors, circuits, various printed boards, various masks and lead frames. It is related to the technology.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices, a resist material is applied onto a silicon wafer and a predetermined resist film image is formed by a normal photo process. Using this as a mask, the unnecessary resist material is removed after etching to form a predetermined circuit. Then, in order to form the next circuit, the cycle of applying the resist material again is repeated. Also, when forming a circuit on various substrates, unnecessary resist material is removed after the resist film image is formed.

At this time, the unnecessary resist material is generally removed by an asher (ashing means), a solvent, a chemical, or the like. However, if the asher is used to remove the resist material, it may take a long time for the work, the impurities in the resist material may be injected into the wafer, and the semiconductor substrate may be damaged. In addition, there is a problem that the working environment is harmed when a solvent or a chemical is used.

Therefore, when removing the resist film image,
A method in which a solution of a high molecular polymer is applied onto a semiconductor substrate having the above image and subjected to a specific treatment such as heating and drying, and then the high molecular polymer and the resist material are integrally peeled from the high molecular polymer. A method has been proposed in which the following adhesive sheets are attached to the upper surface of the resist film image, subjected to a specific treatment such as heat treatment, and then the adhesive sheets and the resist material are integrally peeled off. In particular, the latter method is drawing attention as a simple removal method.

[0005]

However, in the method using the adhesive sheet, the harmful metal derived from the adhesive sheet adheres to the wafer from which the resist has been peeled off by transfer, transfer, etc. There was a problem that it adversely affected the electrical characteristics of the. For this reason, a method has been adopted in which harmful metals contained in the constituent materials of the adhesive sheets are reduced by cleaning and refining, but there are problems such as difficulty in reducing harmful metals and high cost.

In view of the above-mentioned circumstances, the present invention peels off unnecessary resist film images on an article by using adhesive sheets and removes harmful metals derived from the adhesive sheets from the articles. The purpose is to suppress the adhesion to the top and prevent adverse effects on the electrical characteristics of an article such as a semiconductor wafer.

[0007]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies, and as a result, as an adhesive sheet, the adhesive layer contains a trapping agent capable of binding a harmful metal. The resist film image can be easily removed from an article such as a semiconductor wafer by using
The inventors have found that it is possible to suppress the adhesion of harmful metals that adversely affect the electric characteristics and the like to the above-mentioned articles, and have completed the present invention.

That is, according to the present invention, an adhesive sheet is formed by a film base material and an adhesive layer provided on the film base material (or a separator attached to the film base material and the adhesive layer surface).
Adhesive sheet for resist removal, such as sheets and tapes, characterized in that the adhesive layer contains a trapping agent that composes a sheet and is capable of binding to harmful metals of these constituent members.
The adhesive sheet having the above-mentioned constitution is peeled off and attached to the article having the resist film image and the adhesive sheet (Claim 1), and the adhesive sheet is attached. If the type is a curable type, after curing it,
A resist removing method (claim 2) is characterized in that the adhesive sheet and the resist material are integrally peeled off to remove the resist material on the article.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An adhesive sheet for resist removal according to the present invention
As the film base material, polyethylene,
The thickness of polypropylene, polyethylene terephthalate, acetyl cellulose, etc. is usually 10-100 μm.
Some plastic films are preferably used. In particular, when the adhesive layer is a photo-curable type, a plastic film that transmits light such as ultraviolet rays is selectively used.

Usually 10 to 180 μm is formed on the film base material.
An adhesive layer of about m is provided to form sheet-shaped or tape-shaped adhesive sheets for resist removal. These adhesive sheets are either rolled into a roll after the release treatment such as silicon treatment is applied to the back side of the film base, or the adhesive layer surface is subjected to release treatment such as silicon treatment. Separate separators made of sheets and the like are attached and rolled into a roll. In other words, the adhesive sheets have a film base material and an adhesive layer (or a separator attached to the film substrate and the adhesive layer surface) as constituent members.

The present invention is characterized in that, in such an adhesive sheet, a trap agent capable of bonding with a harmful metal contained in the above-mentioned constituent member is contained in the adhesive layer. The trapping agent reacts with and traps harmful metals in the adhesive layer, and also reacts with harmful metals contained in the film substrate and the separator which come into contact with the adhesive layer to trap them. Therefore, when the adhesive sheets are attached to a semiconductor wafer or the like, there is little concern that harmful metals derived from the above-mentioned constituent members are transferred or transferred to the above-mentioned article, and adverse effects such as electrical characteristics on the above-mentioned article are remarkable. Suppressed.

Here, the harmful metals are, for a wafer as a semiconductor material, alkali metals, alkaline earth metals, transition metals, etc. of the 2nd, 3rd, 4th and 5th periods of the periodic table, and they are concrete. Include Li, Na, K, Be, Mg, Ca,
Sr, Ti, V, Cr, Mn, Fe, Co, Ni, C
u, Zn, As, Se and the like.

Examples of the trapping agent capable of binding to the harmful metals include ethylenediaminetetraacetic acid, hexamethylenediaminetetraacetic acid, nitrilotriacetic acid, polyaminocarboxylic acid, citric acid, glycine, dimethylglyoxime and oxine, and complexes and ions. A compound that forms a bond is used. These trap agents are appropriately used alone or as a mixture depending on the kind and amount of harmful metals contained in the constituent members of the adhesive sheets. The amount used varies depending on the type and amount of trapping agent or metal, but is usually 100 ppm to 100,000 ppm, preferably 500 to 10,000 ppm, based on the weight of the adhesive layer. If the amount is too small, there is no effect as a trapping agent, and if the amount is too large, there is a problem that the resist removability deteriorates.

Adhesives containing these trapping agents are
The type is not particularly limited as long as it has a pressure-sensitive adhesive property and has a good affinity with the resist material on the article. Preferably, it is preferable to use a curable adhesive that is cured by irradiation with light and is integrated with the resist material.
A photocurable adhesive obtained by adding a photopolymerizable compound and a photopolymerization initiator to a high molecular polymer is preferably used.

The high molecular polymer is various known polymers applied to pressure-sensitive adhesives, for example, general acrylic polymers, polyvinyl alcohol, polyacrylic acid and other synthetic polymers, and natural polymers. As such, any of starch, cellulose polymers such as carboxymethyl cellulose and the like can be used. Usually, a polymer having a weight average molecular weight of 6,000 to 1,000,000 is preferably used. If the molecular weight is too low,
When the adhesive layer and the resist material are peeled together, the film strength is not sufficient, so that breakage or cohesive failure may occur, and it is difficult to peel the resist material sufficiently. If the molecular weight is too high, handling problems are likely to occur.

Among such high molecular weight polymers, an acrylic polymer having an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester as a main monomer is preferably used. This acrylic polymer has an ester of acrylic acid or methacrylic acid and an alcohol having a carbon number of usually 12 or less as a main monomer, and if necessary, a carboxyl group- or hydroxyl group-containing monomer or other modifying agent. It can be obtained by adding a monomer and polymerizing these monomers by a method such as solution polymerization, emulsion polymerization, suspension polymerization or bulk polymerization according to a conventional method.

Acrylic acid, methacrylic acid, itaconic acid and the like are used as the carboxyl group-containing monomer, and hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate are used as the hydroxyl group-containing monomer. Etc. are used respectively. Examples of other modifying monomers include vinyl acetate, vinyl propionate, styrene, (meth) acrylonitrile, acrylamide, glycidyl methacrylate and the like.

The photopolymerizable compound is a non-volatile compound having at least one unsaturated double bond which can be cured by irradiation with light, and the term "non-volatile" as used herein means an adhesive manufacturing process, such as a coating process or a drying process. This means that the compound does not easily volatilize in the process and the like. The amount of the photopolymerizable compound used is usually 200 parts by weight or less per 100 parts by weight of the polymer. If this amount is used too much, the adhesive will flow out during storage,
Not preferred.

Examples of such a polymerizable compound include phenoxy polyethylene glycol (meth) acrylate, ε-caprolactone (meth) acrylate, polyethylene glycol di (meth) acrylate and polypropylene. Glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexahexa (meth) acrylate, urethane (meth) acrylate, epoxy (meth) acrylate
And oligoester (meth) acrylates, and of these, one kind or two or more kinds are used.

The photopolymerization initiator generates a radical upon irradiation with light such as ultraviolet rays, and any known photopolymerization initiator such as benzoin, benzoin ethyl ether and dibenzyl can be used. These photopolymerization initiators,
It is usually used in the range of 0.1 to 10 parts by weight per 100 parts by weight of the high molecular weight polymer.

The photocurable adhesive composed of these components is
0.05~1kg / mm ² elastic modulus before photocuring, so that the 1~500kg / mm ² after photocuring, desirably determine the kind and amount of each component. If the elastic modulus before photo-curing, that is, when attached is too small, the adhesive may flow out during storage, while if it is too large, the integration with the resist material during attachment becomes insufficient, resulting in poor resist removability. Cheap. Further, if the elastic modulus after photocuring is too small, the resist removability is inferior, and if it is too large, the adhesive layer is liable to be cut and the resist removability is also inferior.

In the resist removing method of the present invention, first, the adhesive sheet having the above-mentioned structure is peeled off from the article such as a semiconductor wafer having a resist film image on it, when the separator is attached. And paste. As a result, the adhesive layer and the resist material are integrated, but in order to promote this integration, heating and / or pressure may be applied at the time of attachment. After this integration, if the adhesive sheets are of the curable type, they are cured, and especially for the photocurable type, the ultraviolet rays are irradiated at an irradiation dose of about 300 to 3,000 mj / cm ^2. After light curing, this adhesive sheet
The resist material on the article is removed by peeling the mold and the resist material together.

As a result, the resist film image on the article is easily and surely removed. In addition, on the surface of the article from which the resist material has been removed in this manner, almost no harmful metal derived from the adhesive sheet is transferred or transferred. There is no particular concern about the adverse effects of.

[0024]

Next, an embodiment of the present invention will be described in more detail. The resist film image A, which was the object of peeling and removal in the examples, was formed on a semiconductor wafer by the method of Reference Example 1 below.

Reference Example 1 A resist material consisting of novolak and naphthoquinone diazide was applied to the surface of a 5-inch silicon wafer (bare wafer), and heating, exposure and development were carried out to form a resist film image on the entire surface. This was designated as resist film image A.

Example 1 Acrylic acid / methyl acrylate = 80/20 (weight ratio)
60 g of a copolymer (weight average molecular weight of 330,000), 0.5 g of ethylenediaminetetraacetic acid, 45 g of polyethylene glycol diacrylate, and 2 g of a photopolymerization initiator were added to a methanol solution of a film made of a polyester film having a thickness of 50 μm. It is coated on a substrate and dried in a drying oven at 70 ° C and 130 ° C for 3 minutes each to form an adhesive layer with a thickness of 50 μm, and a photocurable resist removing adhesive sheet is formed. It was made.

Regarding this adhesive sheet, harmful metals (Ca, Fe, Sb) contained in the film substrate and the adhesive layer (however, the adhesive component excluding ethylenediaminetetraacetic acid)
An inductively coupled plasma optical emission spectrometer (hereinafter referred to as ICP
The film substrate was found to have Ca: 0.09 ppm, Fe: 0.85 ppm, Sb:
3.0 ppm, in the adhesive layer, Ca: 0.01 ppm, F
e: 0.05 ppm, Sb: 0.1 ppm.

Next, the above-mentioned adhesive sheet was attached to the resist film image A on the semiconductor wafer with a pressure roll under heating, and then 2 J / ul of ultraviolet light was applied by a high pressure mercury lamp.
Irradiation was carried out at a dose of cm ² to cure the adhesive sheet. After that, peel off the adhesive sheet and the image A,
The image A was removed from the wafer.

Example 2 The above-mentioned silicon-treated surface of a separator made of a silicon-treated polyester film having a thickness of 38 μm was bonded to the adhesive layer surface of the resist-removing adhesive sheet prepared in Example 1. , Adhesive sheet with separator.

The harmful metals contained in the separator are
By ICP emission analysis, Ca: 0.35 ppm, Fe:
The values were 1.11 ppm and Sb: 5.5 ppm. Next, using this adhesive sheet, the resist film image A was peeled off in the same manner as in Example 1 except that the separator was peeled off at the time of sticking to the resist film image A.

Example 3 Butyl acrylate / Ethyl acrylate / Acrylic acid = 8
0/15/5 (weight ratio) copolymer (weight average molecular weight 5
60,000) 60 g, hexamethylenediaminetetraacetic acid 0.3
g, polyethylene glycol dimethacrylate 45 g,
Example 1 using a solution of 2 g of a photopolymerization initiator in ethyl acetate was used.
An adhesive layer having a thickness of 50 μm was formed on the same film substrate as in Example 1 to prepare a photocurable resist removing adhesive sheet.

The harmful metal contained in the above-mentioned adhesive layer (however, the adhesive component excluding hexamethylenediaminetetraacetic acid) was Ca: 0.01 pp by ICP emission analysis.
m, Fe: 0.05 ppm, Sb: 0.1 ppm.
Next, using this adhesive sheet, the resist film image A was peeled and removed in the same manner as in Example 1.

Example 4 The same separator as in Example 2 was attached to the adhesive layer surface of the adhesive sheet for resist removal prepared in Example 3,
An adhesive sheet with a separator was used. Further, using this adhesive sheet, the resist film image A was peeled and removed in the same manner as in Example 1 except that the separator was peeled off at the time of sticking to the resist film image A.

Example 5 Using a methanol solution of 60 g of polyacrylic acid (weight average molecular weight of 660,000), 0.5 g of citric acid, 50 g of ethylene oxide-modified oligoester triacrylate, and 2 g of a photopolymerization initiator, An adhesive layer having a thickness of 50 μm was formed on the same film substrate as in Example 1 in the same manner as in Example 1 to prepare a photocurable resist removing adhesive sheet.

The harmful metals contained in the above-mentioned adhesive layer (however, the adhesive component excluding citric acid) were Ca: 95.0 ppm, Fe: 0.90 pp by ICP emission analysis.
m, Sb: 0.1 ppm. Next, this adhesive sheet
Resist film image A in the same manner as in Example 1
Was removed.

Example 6 The same separator as in Example 2 was attached to the adhesive layer surface of the resist removing adhesive sheet prepared in Example 5,
An adhesive sheet with a separator was used. Further, using this adhesive sheet, the resist film image A was peeled and removed in the same manner as in Example 1 except that the separator was peeled off at the time of sticking to the resist film image A.

Comparative Example 1 An adhesive sheet for resist removal was prepared in the same manner as in Example 1 except that the trap agent (ethylenediaminetetraacetic acid) was omitted. Using this adhesive sheet, the resist film image A was peeled and removed in the same manner as in Example 1.

Comparative Example 2 The same separator as in Example 2 was attached to the adhesive layer surface of the adhesive sheet for resist removal prepared in Comparative Example 1,
An adhesive sheet with a separator was used. Further, using this adhesive sheet, the resist film image A was peeled and removed in the same manner as in Example 1 except that the separator was peeled off at the time of sticking to the resist film image A.

Comparative Example 3 An adhesive sheet for resist removal was prepared in the same manner as in Example 3 except that the trap agent (hexamethylenediaminetetraacetic acid) was omitted. Using this adhesive sheet, the resist film image A was peeled and removed in the same manner as in Example 1.

Comparative Example 4 The same separator as in Example 2 was attached to the adhesive layer surface of the adhesive sheet for resist removal prepared in Comparative Example 3,
An adhesive sheet with a separator was used. Further, using this adhesive sheet, the resist film image A was peeled and removed in the same manner as in Example 1 except that the separator was peeled off at the time of sticking to the resist film image A.

Comparative Example 5 An adhesive sheet for resist removal was prepared in the same manner as in Example 5 except that the trap agent (citric acid) was omitted. Using this adhesive sheet, the resist film image A was peeled and removed in the same manner as in Example 1.

Comparative Example 6 The same separator as in Example 2 was attached to the adhesive layer surface of the adhesive sheet for resist removal prepared in Comparative Example 5,
An adhesive sheet with a separator was used. Further, using this adhesive sheet, the resist film image A was peeled and removed in the same manner as in Example 1 except that the separator was peeled off at the time of sticking to the resist film image A.

With respect to the results of peeling and removing the resist film image A according to the above Examples 1 to 6 and Comparative Examples 1 to 6, the resist removability was evaluated according to the following criteria. A: No resist is recognized. A: Trace amount of resist is recognized. Δ: The resist is only partially removed. X: The resist is not removed at all.

The result of the resist removability is transferred from the adhesive sheet for resist removal used in each example to a harmful metal (Ca, Fe, S) deposited on the silicon wafer by transfer or transfer.
It is shown in Table 1 below together with the amount of b). In addition, the above-mentioned measurement of the harmful metal is carried out at room temperature (20 ° C.) by sticking the above-mentioned adhesive sheet on a bare wafer on which the resist film image A is not formed, from the viewpoint of examining the amount of the harmful metal derived from the adhesive sheet. )
After peeling off the metal element on the wafer surface with total reflection fluorescence X
By line analysis (TREX-610T manufactured by Technos),
The surface is measured at 5 points and the average value is shown.

[0045]

As is clear from the results shown in Table 1 above, when the adhesive sheets of Examples 1 to 6 of the present invention were used, good results were obtained in the removability of the resist film image A and the wafer surface was obtained. It can be seen that the adhesion of harmful metals to the is greatly suppressed.

[0047]

INDUSTRIAL APPLICABILITY As described above, according to the present invention, as the adhesive sheet for removing resist, the one in which the trapping agent capable of binding the harmful metal in the adhesive layer is used is used to obtain the semiconductor wafer. It is possible to easily remove the unnecessary resist film image on the article, etc., and it is possible to greatly suppress the adhesion of harmful metals to the semiconductor wafer and the like, and to prevent adverse effects on the electrical characteristics and the like due to the metals.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryo Chikada 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation

Claims (2)

[Claims] 1. An adhesive sheet comprising a film substrate and an adhesive layer (or a separator attached to the adhesive layer surface) provided on the film substrate. An adhesive sheet for resist removal, characterized in that a trapping agent capable of binding a harmful metal is contained in the adhesive layer. 2. The adhesive sheet according to claim 1 is peeled off and attached to an article having a resist film image when the separator is attached, and the adhesive sheet is attached. If the kind is a hardening type, after hardening it,
A resist removing method, characterized in that the adhesive sheet and the resist material are integrally peeled off to remove the resist material on the article.