JP2002296804A - Resist stripper and method for stripping resist using the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To obtain a resist stripping solution excellent in safety. SOLUTION: A resist stripping solution containing t-butylhydrazine or a salt thereof is prepared and used for stripping the resist.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positive resist stripping solution used in the manufacture of semiconductor devices such as ICs and LSIs and liquid crystal panel devices, and its use.

[0002]

2. Description of the Related Art When manufacturing semiconductor elements such as ICs and LSIs and liquid crystal panel elements, a wiring layer or an insulating film is formed as a base, a resist is applied thereon, and dried to obtain a resist substrate. Exposure and development are performed to form a resist pattern.
Next, an etching process is performed using the pattern as a mask, and the pattern is transferred to the underlying wiring layer or insulating film. Thereafter, there is a step of removing the unnecessary resist film, and the following two methods are generally employed. One method is to directly remove the unnecessary resist film using a stripper, and the other is to remove the resist and its residue after removing the resist by incineration with oxygen plasma or the like. It is a method of removing using. In any of the methods, the stripping solution is used for removing the resist by a method such as a dipping method or a spraying method in the production process.

[0003] Conventionally, as these stripping solutions, an acid stripping solution obtained by mixing a phenolic compound or a chlorine-based solvent with alkylbenzenesulfonic acid, or an alkaline stripping solution comprising a water-soluble organic amine and a polar solvent has been used. Of the alkaline strippers, those having relatively high alkalinity can be used in any of the above-mentioned methods, and various alkaline strippers have been proposed. As such a stripping solution, for example, a stripping solution obtained by adding a compound having an aromatic or heterocyclic structure as a corrosion inhibitor to an organic polar solvent and an amine (Japanese Unexamined Patent Application Publication No.
JP-A-45894), a stripping solution comprising a nucleophilic amine compound having an oxidation-reduction potential, an organic solvent and water (JP-A-6-2)
No. 66119), a stripper obtained by adding a specific reducing compound to an organic solvent and a nucleophilic amine (JP-A-7-21924).
No. 1).

Japanese Patent Application Laid-Open No. 6-266119 proposes using hydrazine or a hydrazine derivative as a nucleophilic amine compound having oxidation and reduction.
Only hydrazine is used in the examples.

[0005]

In recent years, importance has been placed on the toxicity and safety of stripping solutions. The hydrazine widely used stripping solution as described above has explosive, LD ₅₀ is as high as 68 mg / g (mouse), it is also carcinogenic. Accordingly, the present invention has conducted intensive studies in order to obtain a stripping solution comprising a non-toxic and highly safe component while maintaining high detergency, and as a result, the use of t-butylhydrazine or a salt thereof achieves this object. And found that the present invention was completed.

[0006]

Accordingly, an object of the present invention is to provide a resist stripping solution containing t-butylhydrazine or a salt thereof, and further comprising forming a resist film on a substrate having a metal layer and an oxide film layer. Forming, forming a latent image of the pattern on the resist film using actinic radiation,
A step of developing a pattern by developing with a developer, a step of etching the oxide film using the pattern that has been revealed as a mask, and a step of removing the resist by contacting the substrate after etching with the stripping solution. A resist stripping method is provided.

[0007]

DETAILED DESCRIPTION OF THE INVENTION t- butyl hydrazine to be used in the present invention _{(t-C 4 H 6 -NH} -NH 2) is safe without explosive, _{LD 50} is 680 mg / g (mouse)
Not carcinogenic. t-Butylhydrazine is readily available in a 50% aqueous solution. Further, an inorganic acid salt such as a hydrochloride or a sulfate thereof can also be used. Also t
-Butylhydrazine may be used alone or in combination with its salt. Since the presence of residual metal ions poses a problem in semiconductor manufacturing, t-
It is desirable to use butylhydrazine alone.

The stripping solution of the present invention contains the above-mentioned t-butylhydrazine. Further, in order to ensure good peelability and corrosion resistance, alkanolamine compounds,
Various compounds such as water, aromatic hydroxy compounds and aromatic carbonyl compounds can be contained. The stripping solution of the present invention, in addition to t-butylhydrazine, hydrazine,
Although other hydrazine compounds such as methylhydrazine, isopropylhydrazine, and benzylhydrazine may be contained, 90% by weight or more, preferably 95% by weight or more, more preferably 99% by weight or more of all hydrazine compounds are t-butyl. Hydrazine is preferable because high safety is ensured.

The alkanolamine compound used in the present invention includes, for example, ethanolamines such as monoethanolamine, diethanolamine and triethanolamine; monopropanolamine, dipropanolamine, tripropanolamine, isopropanolamine, diisopropanolamine and the like. Propanolamines; N-methylethanolamine, N, N-dimethylethanolamine, N-ethylethanolamine,
N-substituted ethanolamines such as N-diethylethanolamine, N-methylpropanolamine, N, N-
N such as dimethylpropanolamine, N, N-diethylpropanolamine, 2- (2-aminoethoxy) ethanol, 2- (2-aminoethoxy) propanol, 2-amino-1-propanol and 1-amino-2-propanol -Substituted propanolamines; and the like. These compounds may be used alone or in combination of two or more. Among the above compounds, ethanolamines and N-substituted ethanolamines are preferable from the viewpoint of peelability, and monoethanolamine, triethanolamine and N-methylethanolamine are particularly preferable.

[0010] By adding one or a combination of two or more anticorrosives such as aromatic hydroxy compounds, aromatic carbonyl compounds or salts thereof, the anticorrosive property for further preventing corrosion of the metal film on the substrate. Is obtained. Examples of the aromatic hydroxy compound include aromatic dihydroxy compounds such as catechol, resorcinol, and hydroquinone, and aromatic trihydroxy compounds such as pyrogallol. As the aromatic carbonyl compound,
Salicylic acid, anthranilic acid, gallic acid, benzoic acid,
Examples include aromatic carboxy compounds such as hydroxylbenzoic acids, aromatic ester compounds such as alkyl gallate, and salts of aromatic carbonyl compounds such as ammonium benzoate.

The stripping solution of the present invention may further contain a polar solvent, if necessary. Specific examples of the polar solvent include formamide, dimethylformamide, N-
Formamides such as methylformamide, N, N-dimethylacetamide, N-methylacetamide, N, N
-Acetamides such as diethylacetamide; pyrrolidones such as N-methyl-2-pyrrolidone and N-ethyl-2-pyrrolidone; imidazolidines such as dimethylimidazolidine; and sulfoxides such as dimethylsulfoxide. These compounds may be used alone or in combination of two or more.

Among the stripping solutions of the present invention, those containing water and an alkanolamine compound in addition to t-butylhydrazine are preferred in that they have a safe and strong stripping property. When t-butylhydrazine is used as an aqueous solution, water derived from the aqueous solution is also water constituting the stripping solution, and water added separately from the t-butylhydrazine aqueous solution is also water constituting the stripping solution. The mixing ratio of each component of such a stripping solution is such that the t-butylhydrazine compound is 2-3
5% by weight, preferably 10-35% by weight, water is 2-70%
%, Preferably 15 to 55% by weight, and the alkanolamine compound is 2 to 90% by weight, preferably 10 to 70% by weight. When a polar solvent is used, the polar solvent is generally used in a proportion of 30 to 95%, preferably 40 to 90%. When the aromatic hydroxy compound and the aromatic carbonyl compound are respectively blended at a ratio of 0.1 to 10% by weight, preferably 0.5 to 10% by weight, a stripper having excellent anticorrosion properties can be obtained.

In the stripping method of the present invention, a step of forming a resist film on a substrate having a metal layer and an oxide film layer, and a step of forming a latent image of a pattern on the resist film using actinic radiation are developed with a developer. A step of visualizing the pattern by this, a step of etching the oxide film using the pattern that has been visualized as a mask, and a step of removing the resist by contacting the etched substrate with the stripping solution of the present invention.
Such a peeling method will be specifically described below.

On a substrate such as a silicon wafer, a metal layer such as aluminum is formed by a method such as CVD on a metal such as aluminum, and then a metal wiring substrate in which an oxide film such as silicon oxide is formed on the metal layer is obtained. . After a resist is applied on the oxide film of the substrate and dried to form a resist film, a latent image of a pattern is formed on the resist film using active radiation such as g-rays, i-rays, and far ultraviolet rays. The latent image is developed with a developing solution to visualize the pattern, and using this pattern as a mask, the oxide film is dry-etched with a fluorine-based etching gas, plasma, or the like. Then, the resist remaining substrate is brought into contact with the stripping solution of the present invention to remove the resist directly, or the resist is ashed according to a conventional method, and after removing a part of the resist, the substrate is stripped of the present invention. The resist and the residue are removed by contact with a liquid. The substrate after contact with the stripper is washed with ultrapure water,
By drying, the substrate has no resist residue. There is no particular limitation on the method of bringing the stripping solution into contact with the substrate, and a general method such as a dipping method in which the substrate is immersed in the stripping solution or a spraying method in which the stripping solution is sprayed on the substrate can be used.
The stripping solution of the present invention is 100 ° C. or less, preferably 40 to 1
The resist can be removed at 00 ° C., more preferably at 50 to 75 ° C.

The resist used in the above steps is not particularly limited, and a general resist may be used. The pattern obtained by using this resist may be either a positive type or a negative type, but the positive type is desirable from the viewpoint that the stripping solution of the present invention exhibits good stripping performance. As the developing solution, the developing solution may be arbitrarily designed according to the solubility of the resist, and examples thereof include a general developing solution such as a 2.38% aqueous solution of tetramethylammonium hydroxide and xylene. The developing method may be a general method such as a paddle method, a dipping method, and a spray method.

[0016]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. (Examples 1 to 5 and Comparative Examples 1 and 2) Aluminum and an oxide film were sequentially formed on a silicone wafer, and a commercially available positive resist composition was applied on the oxide film and dried to form a resist film. Thereafter, the pattern was transferred, and the oxide film was etched and removed using the pattern as a mask. Subsequently, the resist film was removed by 80% or more by ashing to obtain a wafer in which a residue in which inorganic and organic substances were mixed remained. Next, the wafer was immersed in a stripper having the composition shown in Table 1 maintained at a liquid temperature of 65 ° C., washed with ultrapure water, and then spin-dried. The processed wafer was observed with an SEM (scanning electron microscope) to confirm the releasability from the presence or absence of the remaining resist film and etching residue, and the degree of corrosion of aluminum generated by etching. These criteria are as follows. Table 1 shows the obtained results.

(1) Peelability ：: Peeled in 10 minutes or less ：: Peeled in 10 to 20 minutes ×: Cannot be peeled even after 20 minutes or more The surface is slightly degraded but not at the level of corrosion. △: Partially corroded ×: Intensely corroded or completely dissolved

[0018]

[Table 1]

The abbreviations in the table are as follows. MEA: monoethanolamine AEE: 2- (2-aminoethoxy) ethanol NMEA: N-methyl-2-ethanolamine DMAC: N, N-dimethylacetamide NMP: N-methyl-2-pyrrolidone DMSO: dimethylsulfoxide

From the above results, by selecting t-butylhydrazine from the hydrazines which have not been confirmed to be toxic, the resist stripping solution of the present invention having high safety and excellent stripping properties can be obtained. By using this stripping solution, it is possible to sufficiently strip off the photoresist and its residues that have been exposed to the etching step or the ashing step and to be able to strip the resist without corroding a metal film such as aluminum. all right.

Claims (5)

[Claims] 1. A resist stripping solution containing t-butylhydrazine or a salt thereof. 2. A resist stripping solution comprising t-butylhydrazine or a salt thereof, an alkanolamine compound and water. 3. The resist stripping solution according to claim 2, further comprising an aromatic hydroxy compound. 4. The resist stripping solution according to claim 3, further comprising an aromatic carbonyl compound or a salt thereof. 5. A step of forming a resist film on a substrate having a metal layer and an oxide film layer, a step of forming a latent image of the pattern on the resist film using active radiation, and developing the pattern by developing with a developer. A step of visualizing, a step of etching an oxide film using the pattern that has been revealed as a mask, and a step of removing the resist by contacting the etched substrate with the stripping solution according to any one of claims 1 to 4. Resist stripping method.