JP2003207906A - Method of removing cyanide in peeling liquid for used resist - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of removing the cyanide in the peeling liquid for used resist containing an alkanolamine compound and restoring the peelability of the peeling liquid and to prevent the degradation in the working environment based on thickening of a cyanide. <P>SOLUTION: The method of removing the cyanide in the peeling liquid comprising compounding the alkaline compound with the peeling liquid for the used resist containing the alkanolamine compound. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a cyanide compound from a used resist stripping solution, and more specifically, it relates to an alkanolamine compound used in the production of semiconductor devices such as IC and LSI or liquid crystal display devices. The present invention relates to a method for removing a cyanide compound contained in a resist stripping solution.

[0002]

2. Description of the Related Art For semiconductor elements such as ICs and LSIs, and liquid crystal display elements, a photoresist is uniformly applied on a substrate such as a silicon wafer or glass, and the photoresist is exposed and developed to form a resist pattern. It is manufactured by selectively etching or diffusing the exposed substrate using the pattern as a mask, and then peeling and removing the unnecessary resist pattern from the substrate.

A stripping solution is used for stripping and removing the resist pattern. Examples of the stripping solution include organic solvents such as methyl ethyl ketone, acetone, and methanol, and organic sulfonic acid series containing alkylbenzene sulfonic acid as an essential component. Stripping solutions, organic amine-based stripping solutions containing alkanolamine compounds such as monoethanolamine, and the like are used. In particular, a stripping solution containing an alkanolamine compound (hereinafter referred to as an alkanolamine compound-containing stripping solution) is a resist film that has been altered by dry etching, ashing, ion implantation, etc., which is adopted in the manufacturing process of semiconductor elements and liquid crystal display elements. It is widely used because it can be effectively peeled off and it does not corrode a conductive metal film such as aluminum, copper or aluminum alloy formed on a substrate.

However, when the resist pattern stripping treatment is repeated using the alkanolamine compound-containing stripping solution, the removed resist and water are mixed in the alkanolamine compound-containing stripping solution, or the stripping solution itself deteriorates. As a result, the releasability is lowered. Therefore, it is common to recycle and reuse, but the conventional reclaiming process, distillation, cannot sufficiently recover the strippability of the alkanolamine compound-containing stripper, and the reduction in strippability leads to an increase in the number of recycles. Therefore it was getting bigger.

[0005]

Therefore, as a result of continuing the earnest research on the reduction of the stripping property, the present inventor has found that in addition to the mixing of resist and water which have been dissolved and removed, or the deterioration of the stripping liquid itself, the stripping liquid It was found that the cyan compound caused by the alkanolamine compound contained in had a great influence.
The present invention has been completed by finding that the cyanide compound can be easily removed by adding an alkali compound, the peelability is recovered, and the deterioration of the working environment due to the cyanide compound that is concentrated at each regeneration can be prevented. It was done. That is,

The present invention is a method for removing a cyanide compound in a used resist stripping solution containing an alkanolamine compound.

It is an object of the present invention to provide a method for recovering the strippability of a used resist stripping solution containing an alkanolamine compound.

Another object of the present invention is to provide a method for preventing deterioration of the working environment of a used resist stripping solution containing an alkanolamine compound.

[0009]

Means for Solving the Problems The present invention for achieving the above object is characterized in that an alkali compound is added to a used resist stripping solution containing an alkanolamine compound, and a cyanide in the used resist stripping solution is characterized. The present invention relates to a method for removing a compound.

The present invention will be described in detail below. The used resist stripper used in the removal method of the present invention is not particularly limited as long as it is a resist stripper containing an alkanolamine compound, but practically, for a resist containing an alkanolamine compound and an organic solvent. A stripper is preferred. Specific examples of the alkanolamine compound include monoethanolamine, 2- (2-aminoethylamino) ethanol, diethanolamine, 2-ethylaminoethanol, dimethylaminoethanol and ethyldiethanolamine. The alkanolamine compounds may be used alone or in combination, but monoethanolamine is particularly preferable because of excellent releasability. Specific examples of the organic solvent include sulfoxides such as dimethyl sulfoxide, dimethyl sulfone, diethyl sulfone, bis (2-hydroxyethyl) sulfone, tetramethylene sulfone and other sulfones, N, N-dimethylformamide, N-. Methylformamide, N, N-dimethylacetamide, N-methylacetamide, N, N
-Amides such as diethylacetamide, N-methyl-2
-Lactams such as pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-hydroxymethyl-2-pyrrolidone and N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazo Lidinone, 1,3-diethyl-2-imidazolidinone, 1,3
-Imidazolidinones such as diisopropyl-2-imidazolidinone, γ-butyrolactone, lactones such as δ-valerolactone, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,
Polyhydric alcohols such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol monobutyl ether, and derivatives thereof are listed, and they may be used alone or in combination. , Especially dimethyl sulfoxide,
Polyhydric alcohols such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-diisopropyl-2-imidazolidinone, and diethylene glycol monobutyl ether are used to remove the resist-modified film. Excellent and preferable.

The ratio of the alkanolamine compound and the organic solvent in the resist stripping composition is preferably in the range of alkanolamine compound: organic solvent = 90 to 10:10 to 90 (weight ratio). If it deviates from the above range, the peeling effect cannot be sufficiently exhibited, which is not preferable.

The removal method of the present invention relates to a method for removing a cyan compound in a stripping solution containing an alkanolamine compound used for stripping and removing a resist pattern formed on a substrate of a semiconductor device or a liquid crystal display device by a photoresist method. , In that method, the resist and the altered substance dissolved and removed from the used alkanolamine compound-containing stripping solution are separated,
It then consists of compounding and dissolving the alkaline compound.
The content of the alkali compound is 0.01 to 5% by weight, preferably 0.1 to 3% by weight, based on the alkanolamine compound.
If it is less than 5% by weight, the cyanide compound is not sufficiently removed, and if it exceeds 5% by weight, the regeneration effect is not improved, which is wasteful in terms of cost and is not preferable. It is preferable to mix the alkali compound with stirring at room temperature, and if dissolved at high temperature, the cyan compound absorbed in the alkanolamine compound evaporates, which deteriorates the working environment, which is not preferable. As the alkali compound to be blended, a strong alkali compound is preferable, and examples thereof include sodium hydroxide, potassium hydroxide, calcium hydroxide and the like, and they can be used alone or in combination.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[0014]

EXAMPLES Example 1 THMR-iP, which is a positive photoresist composed of a naphthoquinonediazide compound and a novolak resin, is formed on a silicon wafer having an Al—Si—Cu film of about 1.0 μm deposited thereon.
3300 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied by spinner,
A resist layer having a film thickness of 2.0 μm was formed. This resist layer was exposed through a mask pattern using NSR-2005i10D (manufactured by Nikon Corporation) and developed with a 2.38 wt% tetramethylammonium hydroxide aqueous solution,
A resist pattern was formed. The substrate exposed using the resist pattern as a mask is used as an etching device TSS-6.
000 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was used for dry etching with a mixed gas of chlorine and boron trichloride as an etchant.

The obtained silicon wafer is immersed in a resist stripping solution consisting of 70% by weight of monoethanolamine and 30% by weight of dimethylsulfoxide at 90 ° C. for 20 minutes to remove the resist pattern, which is repeated for 8 hours. This was used as a used resist stripping solution, and the cyan compound in this used resist stripping solution was quantified using an ion chromatography device DX-AQ (manufactured by DIONEX), and a 100 ppb cyan compound was detected.

Next, 1 kg of this used resist stripping solution
Was distilled using a batch distillation apparatus to remove water, thereby distilling out a mixed solution of 900 g of monoethanolamine and dimethyl sulfoxide. Next, 5 g of sodium hydroxide was added to the distilled mixed solution, dissolved at room temperature, charged again in a batch distillation apparatus, and distilled to distill a mixed solution of monoethanolamine and dimethylsulfoxide, which was used for regenerating resist. A stripping solution was obtained. When the cyan compound in the stripping solution for reclaimed resist was analyzed by using the same ion chromatograph apparatus as above, no cyan compound was detected. In addition, Al-Si-C which has been dry-etched by using a stripping solution for recycled resist
When the resist pattern on the u film was stripped,
The resist pattern was peeled off well, and no corrosion was confirmed on the Al-Si-Cu film on the silicon wafer.

Example 2 The silicon wafer obtained by performing the dry etching treatment of Example 1 is dipped in a resist stripping solution consisting of 30% by weight of monoethanolamine and 70% by weight of diethylene glycol monobutyl ether at 90 ° C. for 20 minutes. Thus, the treatment of peeling and removing the resist pattern was repeated for 8 hours to obtain a used resist peeling liquid. When the cyan compound in this used resist stripping solution was quantified using an ion chromatography device DX-AQ (manufactured by DIONEX), a cyan compound of 20 ppb was detected.

Next, 1 kg of this used resist stripping solution
Was distilled using a batch distillation apparatus to remove water, and then monoethanolamine and diethylene glycol monobutyl ether were separately distilled off to obtain 250 g of monoethanolamine and 600 g of diethylene glycol monobutyl ether. Next, 2 g of sodium hydroxide was added to the distilled monoethanolamine and dissolved at room temperature, and 3.5 g of phosphoric acid was added to diethylene glycol monobutyl ether and dissolved at room temperature. Then, each was distilled with a batch distillation apparatus. The monoethanolamine and diethylene glycol monobutyl ether were regenerated. When the cyan compound in the regenerated monoethanolamine and diethylene glycol monobutyl ether was analyzed using the same ion chromatography apparatus as above, no cyan compound was detected. Further, regenerated monoethanolamine and diethylene glycol monobutyl ether were blended in the same ratio as the above resist stripping solution to obtain a reclaimed resist stripping solution. When the resist pattern on the dry-etched Al-Si-Cu film was stripped using this reclaimed resist stripping solution, the resist pattern was stripped well, and Al-Si-Cu on the silicon wafer was stripped. No corrosion was observed on the film.

[0019]

According to the removing method of the present invention, the cyan compound in the used resist stripping solution containing the alkanolamine compound is removed to recover the strippability of the resist stripping solution and to concentrate the cyan compound. This is a method for preventing deterioration of the work environment based on the above.

Claims (3)

[Claims] 1. A method for removing a cyanide compound from a used resist stripping solution, which comprises adding an alkali compound to the used resist stripping solution containing an alkanolamine compound. 2. The method for removing a cyanide compound in a used resist stripping solution according to claim 1, wherein the alkali compound is at least one selected from sodium hydroxide, potassium hydroxide and calcium hydroxide. . 3. The method for removing a cyanide compound in a used resist stripping solution according to claim 1, wherein the content of the alkali compound is 0.01 to 5% by weight based on the alkanolamine compound.