JP2003228181A - Stripper for photoresist - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stripper for a resist having such properties that the stripper has low vapor pressure and little volatilization of an organic component; the stripper is less hazardous for explosion by volatized vapor; a photoresist film or a photoresist film remaining after etching the photoresist film applied on an inorganic substrate or a photoresist residue such as modified film remaining after etching and then ashing the photoresist film can be easily stripped with the stripper; fine processing can be performed in the stripping process while inorganic substrates of various kinds of materials are completely free from corrosion; and circuit wiring of high accuracy can be produced. <P>SOLUTION: An ionic solvent is used for the stripper for a photoresist. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photoresist stripping solution using an ionic solvent. To be more specific, both residual materials such as photoresist films and altered films used in the manufacture of integrated circuits such as ICs and LSIs, display devices such as LCDs and EL elements, printed circuit boards, micromachines, DNA chips, etc. The present invention relates to a stripping solution for photoresists, which has excellent strippability, excellent corrosion resistance to a substrate, low volatility, and low flammability.

[0002]

2. Description of the Related Art Ionic solvents are also called room temperature molten salts,
Properties such as relatively high dielectric constant and non-volatility, which are different from those of conventional solvents, have attracted attention, and research has progressed as reaction solvents, battery electrolytes, and capacitor materials (T. Welton, Chem. Rev. 9
9, 2071 (1999), Adult, Chemistry, 55, 68 (2000)). However, the study as a stripping solution for photoresist, which is the object of the present invention, has not been conducted at all. Conventionally,
Alkyl halides typified by trichlorethylene have been used as a stripping solution for residues such as photoresist films and altered films, but their use has been refrained from causing ozone layer depletion. As an alternative to this, an alkaline stripping solution is often used. For example, TOK106 from Tokyo Ohka
Is an alkanolamine and dimethylsulfoxide.
The resist stripping solution and the residue cleaning solution described in JP-A 6-266119 are solutions of alkanolamine, hydroxylamine, catechol and water. Since the resist stripping solution and the residue cleaning solution containing these organic solutions have a considerable vapor pressure, further reduction of volatile components has been required as an approach to environmental problems. Also, it is preferable that the work environment has a small amount of volatile components. Furthermore, since the vapor pressure is high, there is a danger of explosion under the condition that it is mixed with oxygen, and it is necessary to use expensive explosion-proof equipment for the device used. Further, hydroxylamine, which is said to have a high resist stripping ability, has a risk of exploding by itself. Further, the alkaline stripping solution is generally used by heating in many cases, and has a drawback that vapor of an organic component is more likely to diffuse.

[0003]

DISCLOSURE OF THE INVENTION It is an object of the present invention to have a low vapor pressure, a low volatility of organic components, a low risk of explosion due to volatilized vapor, and a coating on a photoresist film or an inorganic substrate. The photoresist film remaining after etching the photoresist film or the photoresist residue such as the deteriorated film remaining by ashing after etching the photoresist film can be easily peeled off, and at that time, the inorganic substrate of various materials is completely corroded. It is an object of the present invention to provide a resist stripping solution that enables fine processing without using the resist and can manufacture highly accurate circuit wiring.

[0004]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that an ionic solvent is used as a stripping solution for photoresist. The ionic solvent is a substance having an ionic bond, and is therefore characterized by a low vapor pressure and a small amount of volatile organic substances.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The photoresist stripping solution of the present invention contains at least one ionic solvent. The ionic solvent used in the present invention is represented by the formula Q ⁺ A ⁻ , and preferably forms a liquid salt at a temperature of 100 ° C. or lower (melting point: 100 ° C. or lower). Particularly preferably, it forms a liquid salt at a temperature of 50 ° C. or lower (melting point: 50 ° C. or lower).

In the above formula Q ⁺ A ⁻ , Q ⁺ is preferably a cation selected from the group consisting of imidazolium cations, pyridinium cations and quaternary ammonium cations represented by the following formula.

[0007]

[Chemical 1]

In the formula, R'is an alkyl group having 1 to 16 carbon atoms, an aryl group having 6 to 16 carbon atoms, or 3 to 1 carbon atoms.
6 is a cycloalkyl. R is hydrogen and has 1 to 16 carbon atoms
Is an alkyl group having 6 to 16 carbon atoms, or a cycloalkyl having 3 to 16 carbon atoms.

A ^- is preferably an anion represented by the following formula.

[0010]

[Chemical 2]

Particularly, an ionic solvent in which R in the formula of cation is methyl and R'is an alkyl group having 1 to 16 carbon atoms or an aryl group having 6 to 16 carbon atoms has a low melting point and is easily available. preferable.

Specific examples of the ionic solvent used in the present invention include 1-ethyl-3-methylimidazolidinium tetrafluoroborate, 1-butyl-3-methylimidazolidinium tetrafluoroborate and 1-hexyl. -3-Methylimidazolidinium tetrafluoroborate, 1-octyl-3-methylimidazolidinium tetrafluoroborate, 1-ethyl-3-methylimidazolidinium hexafluorophosphate, 1-butyl-3-methylimidazolidinium Hexafluorophosphate, 1-hexyl-3-methylimidazolidinium hexafluorophosphate,
1-octyl-3-methylimidazolidinium hexafluorophosphate, 1-ethyl-3-methylimidazolidinium methylsulfate, 1-butyl-3-methylimidazolidinium methylsulfate, 1-hexyl-3-methyl Imidazolidinium methylsulfate, 1-octyl-3methylsulfate, 1-ethyl-3-methylimidazolidinium trifluoromethanesulfate, 1-butyl-3-methylimidazolidinium trifluoromethanesulfate, hexylpyridinium tetrafluoro Examples thereof include borate, trimethylhexyl ammonium bis (trifluoromethane) sulfonimide, 1-ethyl-3-methylimidazolidinium bis (trifluoromethane) sulfonimide and the like. The ionic solvent used in the present invention is not limited to the above, and is not limited as long as it is an ionic solvent.

There is no problem in adding other ionic substances to the photoresist stripping solution of the present invention. Corrosion by adding tetramethylammonium hydroxide, tetraethylammonium hydroxide, choline hydroxide, tetramethylammonium tetrafluoroborate, tetramethylammonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate, resist removability, It becomes easy to change the melting point.

Halogen may be added to the photoresist stripping solution of the present invention. In particular, when fluorine is contained as halogen, it is easy to control the peelability of the resist and the corrosiveness of the material. Further, it has an advantage that it can be easily collected because it is difficult to mix with other solvents.

By blending a high-boiling-point organic solution with the photoresist stripping solution containing the ionic solvent of the present invention, the resist stripping property can be controlled or water can be contained. The organic solution is not particularly limited as long as it can be mixed with the above ionic solvent. It is preferably a water-soluble organic solution. Examples are ethylene glycol,
Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether,
Propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, diethylene glycol dimethyl ether, ether solutions such as dipropylene glycol dimethyl ether, formamide, monomethylformamide,
Dimethylformamide, monoethylformamide, diethylformamide, acetamide, monomethylacetamide, dimethylacetamide, monoethylacetamide, diethylacetamide, N-methylpyrrolidone, N
An amide solution such as ethylpyrrolidone, an alcohol solution such as methyl alcohol, ethyl alcohol, isopropanol, ethylene glycol, propylene glycol, a sulfoxide solution such as dimethyl sulfoxide, dimethyl sulfone, diethyl sulfone, bis (2-hydroxy sulfone, tetra Sulfone-based solution such as methylene sulfone, 1,3-dimethyl-2-imidazolidinone, 1,
3-diethyl-2-imidazolidinone, 1,3-diisopropyl-2-imidazolidinone and other imidazolidinone-based solutions, γ-butyrolactone, δ-valerolactone and other lactone-based solutions, ethanolamine, methylethanolamine, Examples include amine-based solutions of diethylenetriamine and aminoethoxyethanol. Of these, those with a boiling point of 150 ° C or higher have a low vapor pressure and are easy to use.

In the present invention, the concentration of the ionic solvent is in the range of 5 to 100% by weight based on the total amount of the stripping solution. 5
When the content is less than or equal to wt%, unlike the gist of the present invention, the function of the ionic solvent cannot be fully utilized.

The use of the organic solution is not limited, but the concentration may be determined in consideration of the viscosity, specific gravity or etching of the composition, ashing conditions and the like. 95 when used
It can be used in the following concentrations by weight: Particularly preferably, the concentration is 75% by weight or less.

The blending amount of water is not limited, but the blending amount may be determined in consideration of etching and ashing conditions. It is usually used in the range of 50% by weight. It is particularly preferably 40% by weight or less.

The temperature for producing a semiconductor element by stripping the resist using the photoresist stripping solution of the present invention is usually in the range of room temperature to 150 ° C., but particularly at 70 ° C. or higher, the ionic solution is used. By utilizing the characteristics of, the load on the environment of volatile organic substances is smaller than that of conventional products.

The stripping solution for photoresists of the present invention is particularly suitable for stripping a photoresist residue formed on an inorganic substrate on which metal wiring is formed, stripping of a resist residue such as a photoresist film and an altered film, and a metal. It has the effect of being excellent in both the corrosion resistance of the wiring and the inorganic substrate.

As the metal wiring, aluminum (A
l); Aluminum alloys (Al alloys) such as aluminum-silicon (Al-Si) and aluminum-silicon-copper (Al-Si-Cu); pure titanium (Ti); titanium nitride (TiN), titanium tungsten (TiW). ) And other titanium alloys (Ti alloys); pure copper (Cu) and the like, but not limited thereto.

As the inorganic substrate, silicon, amorphous silicon, polysilicon, silicon oxide film, silicon nitride film, copper and copper alloy, aluminum, aluminum alloy,
Semiconductor wiring materials such as gold, platinum, silver, titanium, titanium-tungsten, titanium nitride, tungsten, tantalum, tantalum compounds, chromium, chromium oxide, chromium alloy, ITO (indium oxide), or gallium-arsenic, Examples thereof include compound semiconductors such as gallium-phosphorus and indium-phosphorus, dielectric materials such as strontium-bismuth-tantalum, and glass substrates for LCDs.

In the method of manufacturing a semiconductor device using the photoresist stripping solution of the present invention, after removing an unnecessary portion of the conductive thin film having a predetermined pattern formed by the resist, the resist is removed by the stripping solution described above. To do. After the etching, an ashing treatment may be carried out if desired, and then the residue generated by the etching can be removed by the above-mentioned stripping solution. The ashing process referred to here is a process of removing a resist made of, for example, an organic polymer by a combustion reaction with oxygen plasma generated in plasma.

The peeling treatment is usually carried out by a dipping method or a shower method. The peeling time is not particularly limited as long as it is a sufficient peeling time, but it is usually 5 to 5.
It takes about 20 minutes.

As a rinsing method after using the photoresist stripping solution of the present invention, an organic solution such as alcohol may be used, or rinsing may be performed with water without any particular limitation.

[0026]

EXAMPLES The present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples.

Example 1 A substrate having a tantalum / glass structure was coated with a resist of PFR-790 and then developed. After that, a circuit was formed through a dry etching process using a fluorine compound. Using this substrate, the resist peeling property was tested. Solvent In
It was immersed in 1-butyl-3-methylimidazolidinium tetrafluoroborate manufactured by novation at 100 ° C. After 5 minutes, the substrate was taken out, rinsed with isopropanol and water, blown with nitrogen gas and dried, and then observed with an optical microscope. The resist was completely stripped. There was no odor or vapor during the resist stripping process.

Example 2 A substrate with a resist was immersed in trimethylhexyl ammonium bis (trifluoromethane) sulfonimide at 150 ° C. in the same manner as in Example 1. The resist was completely stripped off after 5 minutes. There was no odor or vapor during the resist stripping process.

Example 3 In the same manner as in Example 1, the substrate with resist was immersed at 50 ° C. in a composition liquid containing 5% by weight of trimethylhexyl ammonium bis (trifluoromethane) sulfonimide and 95% by weight of diethylenetriamine. The resist was completely stripped off after 5 minutes.

Comparative Example 1 The substrate of Example 1 was immersed at 100 ° C. in a composition liquid containing 70% by weight of ethanolamine and 30% by weight of dimethyl sulfoxide. The resist was completely peeled off after 5 minutes, but an amine odor and a sulfur-containing compound odor were observed during the peeling process.

Example 4 In order to manufacture a semiconductor element, dry etching was performed using a resist film as a mask to form an Al alloy (Al—Cu) wiring body, and further ashing treatment was performed by oxygen plasma. In the semiconductor device, an oxide film is formed on a silicon substrate, an Al alloy that is a wiring body is formed on the oxide film, and a resist residue remains on the side wall. Note that titanium and titanium nitride are present as barrier metals. The semiconductor element is immersed in 1-butyl-3-methylimidazolidinium tetrafluoroborate at 50 ° C for 30 minutes, rinsed with isopropanol and ultrapure water, and dried.
Observation was carried out in M). The resist residue is completely removed,
There was no corrosion on the wiring body.

Example 5 The same experiment as in Example 2 was carried out using 1-butyl-3-methylimidazolidinium methylsulfate. The resist residue was completely removed, and the wiring body was not corroded.

Example 6 A pattern was formed using a resist on a substrate in which TiN, Cu, SiN and SiO2 were deposited in this order on a silicon substrate. This was dry-etched to etch the upper part of the Cu layer. A resist residue remains on the side wall of the SiO ₂ layer in the exposed portion of the Cu layer. This substrate was immersed in 1-butyl-3-methylimidazolidinium methylsulfate at 100 ° C for 15 minutes. After that, it was rinsed with dimethylacetamide, rinsed with water, and then dried. As a result of SEM observation, both the resist and the resist residue were removed.

Example 7 In the same manner as in Example 6, it was immersed in 1-butyl-3-methylimidazolidinium tetrafluoroborate at 100 ° C. for 15 minutes.
Both the resist and the resist residue were removed.

[0035]

According to the present invention, a resist stripping solution and a residue cleaning solution containing less volatile organic components have become possible. Further, it is less corrosive and can remove the resist in a short time.

Claims (6)

[Claims] 1. A stripping solution for photoresist, which contains an ionic solvent. 2. The stripping solution for photoresist according to claim 1, wherein the content of the ionic solvent is 5% by weight or more. 3. The photoresist stripper according to claim 1, wherein the ionic solvent is a fluorine-containing compound. 4. The stripping solution for photoresist according to claim 1, wherein the melting point of the ionic solvent is 100 ° C. or lower. 5. The stripping solution for photoresist according to claim 1, further comprising an organic solution. 6. The method according to claim 1, further comprising water.
The stripping solution for photoresist according to the item.