JPH10260537A - Resist stripper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resist stripping solution capable of completely stripping and completely removing not only a resist adhered on a substrate but also a side wall protective film made of a resist altered by dry etching. I do. SOLUTION: A resist stripping solution 1 according to the present invention dissolves and strips a resist and a side wall protective film adhered to a substrate 3, and then removes the resist and the sidewall protective film by cleaning using a supercritical fluid 5. Wherein a glycol ether-based solvent is the main component and an organic amine compound is contained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist stripping solution, and more particularly to a resist stripping solution used for stripping and removing a resist adhered on a substrate, in particular, a side wall protective film formed by dry etching. About.

[0002]

2. Description of the Related Art Conventionally, when manufacturing metal wiring of a semiconductor element or a liquid crystal display element, a metal thin film is deposited on a substrate made of Si or the like after employing a technique such as sputtering, and a metal thin film is formed. After patterning the resist applied on the thin film by exposure and development, forming a metal pattern such as a gate electrode and a metal wiring by etching using the patterned resist as a mask has been performed, and after forming the metal pattern, After the unnecessary resist is dissolved and removed with a resist stripper, the resist stripper remaining on the substrate is removed by washing with a rinse agent, alcohol and ultrapure water. Have been done. As the resist stripping solution at this time, it is general to use a resist stripping solution having organic sulfonic acid, alkylene glycol, or the like as a main component and having a high stripping property.

However, even if the use of a resist stripping solution having a high stripping property improves the solubility in a resist, an excellent resist stripping solution or an excellent resist stripping solution is not always required unless the resist stripping solution after washing can be easily removed. This cannot be said to be a resist removal method. Therefore, the inventors of the present invention developed a resist stripping solution, which is a glycol ether-based organic solvent, which can be easily removed by washing, and a resist stripping solution adhering to the washed substrate, which is a supercritical fluid such as carbon dioxide. Remove it, and
The method of immediately drying by returning to normal pressure is already proposed in Japanese Patent Application No. Hei 7-190352 as an excellent resist stripping solution and a resist removing method which can replace the conventional resist stripping solution and the resist removing method. I have.

On the other hand, in recent years, there has been an increasing demand for high integration and high speed of elements and wirings, and fine processing of submicron or less has been demanded. It has been practiced to deposit a metal pattern and form a metal pattern by dry etching. In such fine processing of a metal pattern, it is necessary to employ anisotropic etching and then etch the metal thin film along the thickness direction while preventing side etching from occurring. Usually SiCl ₂ or CCl
_Since a chlorine-based gas such as ₄ is used, halogen radicals and ions are taken into not only the side surface of the resist itself but also the side wall protective film formed along the side surface of the metal pattern.

However, in this case, the side wall protective film is
It is difficult to peel off as compared with a normal resist. These side wall protection films not only cause corrosion by absorbing moisture and generate acid, but also cause poor adhesion of the film deposited on the metal pattern, and furthermore, they may fall off. Therefore, when the resist is removed by washing the substrate, it is necessary to completely peel off and remove the sidewall protective film made of the altered resist.

[0006]

Accordingly, as a resist stripping solution having a high stripping property to the side wall protective film, a composition comprising hydroxylamine, alkanolamine and a polar solvent (JP-A-4-289866), an aromatic ring type A stripping solution which is an aqueous solution containing phenol, an aromatic cyclic carboxylic acid and an organic amine (JP-A-5-259066), and a detergent comprising a nucleophilic amine, an organic solvent and a chelating agent (JP-A-6-266119) ), A release agent composition comprising an organic carboxylic acid amine salt or an organic carboxylic acid ammonium salt, a fluorine compound and an organic solvent (JP-A-7-271)
No. 056) has been already proposed to remove the side wall protective film. However, even in the case of using these resist stripping solutions, it is difficult to completely remove and remove the sidewall protective film, and these resist stripping solutions cause corrosion of the metal thin film. Such inconvenience would occur.

The present invention has been made in view of such inconvenience, and removes not only a resist adhered on a substrate but also a side wall protective film made of a resist altered by dry etching. The purpose of the present invention is to provide a resist stripper that can be completely removed.

[0008]

The resist stripping solution according to the first aspect of the present invention dissolves and strips the resist and the side wall protective film attached to the substrate, and removes the resist by cleaning using a supercritical fluid. A resist stripping solution to be used, which is mainly composed of a glycol ether-based solvent and contains an organic amine compound. In this case, the supercritical fluid is a substance that can flow even at a temperature and pressure exceeding the maximum temperature (critical temperature) and the maximum pressure (critical pressure) inherent to a substance in which gas and liquid cannot coexist. It has the intermediate properties of gas and liquid, can penetrate into fine parts, has a high diffusion coefficient, and can quickly dissolve dissolved contaminants. It is a substance having the characteristic that it becomes gaseous immediately after returning to the pressure state and can be evaporated and dried very easily.

The resist stripping solution according to claim 2 is the resist stripping solution according to claim 1, wherein the content of the organic amine compound is in the range of 1 to 20 wt%. The resist stripping solution according to claim 3 is the resist stripping solution according to claim 1 or 2, wherein the glycol ether solvent is diethylene glycol monomethyl ether. On the other hand, a resist stripping solution according to claim 4 is the resist stripping solution according to any one of claims 1 to 3, wherein the organic amine compound is an alkylamine or an alkylpropyldiamine. Is what you do.

Further, in the resist stripping solution according to claim 5, the alkylamines in the resist stripping solution according to claim 4 may be any one of monopropylamine, dipropylamine, tripropylamine, diisopropylamine and dibutylamine. It is characterized by being. Furthermore, the resist stripping solution according to claim 6 is a resist stripping solution according to claim 4.
Wherein the alkyl propyl diamines in the resist stripping solution described in (1) are 3- (methylamino) propylamine.

[0011]

Embodiments of the present invention will be described below.

The resist stripping solution according to the present embodiment comprises:
Dissolves the resist adhering to the substrate such as Si and peels it off, and is characterized by being removed by washing using a supercritical fluid, where the supercritical fluid is highly safe. Has a critical point that is easy to handle and
It is selected on the condition that it is inexpensive and economical. And substances satisfying these conditions include carbon dioxide, sulfur dioxide, nitrous oxide, ethane, propane,
Freon gas and the like are mentioned, and among these, carbon dioxide (CO ₂ gas) is most suitable as a supercritical fluid when cleaning the resist stripping solution. In other words, carbon dioxide is almost harmless to living organisms,
Since the critical temperature is 31 ° C. and the critical pressure is 70 atm, which is relatively easy to handle, and is inexpensive and easily available, this carbon dioxide is selected as a supercritical fluid.
Of course, the above-mentioned substances other than carbon dioxide may be used as a supercritical fluid for cleaning.

On the other hand, when selecting a resist stripping solution, not only the resist but also a side wall protective film made of a resist altered by dry etching has a high stripping property (solubility) and a supercritical fluid (CO ₂ gas) It is necessary to have high solubility in water and high safety, and substances satisfying these selection conditions include glycol ethers (including glycol diethers), ketones, lactones, pyrrolidones, and ethers. And ester-based and formamide-based organic solvents. In consideration of safety, glycol ether-based, ether-based, pyrrolidone-based, and lactone-based solvents will be listed as candidates, and the strippability with respect to the resist and the side wall protective film and the solubility with respect to the supercritical CO ₂ gas. Conducted an experiment to compare
The experimental results as shown in Table 1 were obtained.

[0014]

[Table 1]

By the way, in this comparative experiment, the following procedure is adopted.

(A) Peelability (solubility) to resist The resist applied on the surface is cured by ultraviolet rays, and
After performing dry etching using a halogen-based gas, a semiconductor substrate that has been subjected to plasma processing using O ₂ gas is prepared as an experimental sample. Then, various solvents shown in Table 1 are maintained at a temperature of 25 ° C.
The test sample was immersed in these solvents for 3 minutes (the target of the stripping time on a mass production basis is usually 8 minutes), and the strippability (solubility) with respect to the resist was confirmed. At this time, the dissolution state of the resist during immersion was visually checked, and the residual state of the resist after immersion was checked with an electron microscope. Has been completely dissolved and removed.

(B) Peelability (solubility) to sidewall protective film A TiN film is formed by sputtering and deposition.
After forming an Al-Si film and a TiW film as a three-layer structure, applying a resist on these surfaces and performing patterning, the patterned resist is cured with an ultraviolet ray and then halogenated. A semiconductor substrate which has been subjected to dry etching with a gas and further subjected to a plasma treatment using an O ₂ gas is prepared as an experimental sample. Then, the various solvents shown in Table 1 were maintained at a temperature of 40 ° C.
By immersion for minutes, the releasability (solubility) with respect to the sidewall protective film was confirmed. Here, the state of the side wall protective film after immersion was confirmed by an electron microscope, and the symbol x in Table 1 indicates that the side wall protective film was not removed at all.

[0018] (c) supercritical CO ₂ gas filled in the solubility pressure vessel for the supercritical CO ₂ gas relative to Table 1
Were added so as to have a concentration of 10 mol% (a target value of the solubility required for high-precision cleaning), and the dissolution state of each solvent was visually confirmed. In Table 1, the symbol ☆ indicates that the solvent was dissolved in a completely uniform state, while the symbol ○ indicates that the solvent was dissolved while being non-uniform.

According to the experimental results of the comparative experiment performed according to the above-described procedure, the solubility to the side wall protective film cannot be obtained by any solvent, and the side wall protective film remains as it is on the substrate. However, it can be seen that diethylene glycol monomethyl ether (DEGME), which is a glycol ether-based organic solvent, exhibits the highest solubility for ordinary resist and supercritical CO ₂ . That is, as already proposed by the inventors of the present invention, when a glycol ether-based organic solvent, specifically, diethylene glycol monomethyl ether is used as a resist stripping solution, high solubility in a resist can be obtained. It has become clear that cleaning with supercritical CO ₂ gas becomes easy. Although diethylene glycol monomethyl ether is used here, the invention is not limited to diethylene glycol monomethyl ether, and similar results can be obtained when triethylene glycol monomethyl ether or ethylene glycol monomethyl ether is used. Have been confirmed by others.

As a resist stripper which dissolves and removes the resist adhering to the substrate and is easily removed by washing using a supercritical fluid, a glycol ether organic solvent has excellent properties. It shows,
The experimental results in Table 1 show that even if such a resist stripping solution made of a glycol ether-based organic solvent is used, the sidewall protective film made of a resist altered due to dry etching cannot be dissolved and removed. It is clear. Therefore, the inventors of the present invention re-examined the means of dissolving and removing the side wall protective film while repeating the experiment again, and found that the resist stripping mainly containing a glycol ether-based solvent and containing an organic amine compound was performed. The finding that the liquid is effective was obtained. Less than,
Explanation will be given based on this finding.

That is, when selecting a resist stripper at this time, not only the resist but also the side wall protective film has a high strippability (solubility) and a high solubility in a supercritical fluid (CO ₂ gas). And
High safety is a selection condition. Based on the above experimental results, a resist stripper containing a glycol ether-based organic solvent as a main component and various organic amine compounds as an additive A is selected. Is done.
Then, a resist stripping solution to which a number of different additives A are added as shown in Tables 2 and 3, respectively, that is, a resist stripping solution containing the additive A with a glycol ether-based solvent as a main component is prepared. In addition, when an experiment was performed to compare the strippability (solubility) of each resist stripper with respect to the sidewall protective film and the corrosiveness with respect to the metal pattern, the experimental results as shown in Tables 2 and 3 were found. Obtained. If the content of the organic amine compound in the resist stripping solution exceeds 20 wt%, it is considered that corrosion of the metal pattern is inevitable. Therefore, in this comparative experiment, the content of the organic amine compound was 1 to 20 wt%. It is within the range.

[0022]

[Table 2]

[0023]

[Table 3]

By the way, in the comparative experiment at this time,
A procedure similar to the above (b) is employed. That is, first, TiN is formed by sputtering and deposition.
After forming each of the film, the Al-Si film, and the TiW film as a three-layer structure, applying a resist on these surfaces and performing patterning, the patterned resist is cured by ultraviolet light. A dry etching with a halogen-based gas is performed, and a semiconductor substrate that has been subjected to a plasma process using an O ₂ gas is prepared as an experimental sample. Then, the various resist strippers shown in Tables 2 and 3 were maintained at a temperature of 40 ° C., and
By immersing the test sample in these resist stripping solutions for 4 minutes, the stripping property (solubility) with respect to the sidewall protective film and the corrosive property with respect to the metal pattern were confirmed.

Here, the state of the side wall protective film and the metal pattern after immersion is confirmed by an electron microscope, and the symbol of solubility in Tables 2 and 3 indicates that the side wall protective film is completely dissolved. Removed, symbol ○ indicates almost complete removal and no problem, symbol △ indicates insufficient removal, and symbol × indicates that the sidewall protective film has not been removed at all. . On the other hand, in Tables 2 and 3, the corrosive symbol ○ indicates that there is no corrosion at all, the symbol △ indicates that it is slightly corroded, and the symbol x indicates that it is corroded.

According to the experimental results of the comparative experiment performed in accordance with the above procedure, the resist stripping solution which improves both the solubility for the side wall protective film and the corrosiveness for the metal pattern is made of an alkylamine or the like. Of any of monopropylamine, dipropylamine, tripropylamine, diisopropylamine and dibutylamine, and 3 of alkylpropyldiamines
It was clarified that the resist stripping solution containing dipropylamine was the most excellent in view of the solubility in the side wall protective film. You can see that it is. Note that alkylamines and alkylpropyldiamines, which are organic amine compounds, are relatively inexpensive and are economically advantageous.

Next, a method for removing the resist and the side wall protective film performed using the resist stripping solution according to the present embodiment will be described with reference to the schematic explanatory view of FIG. In this case, a resist stripping solution 1 obtained by mixing 80 wt% of diethylene glycol monomethyl ether and 20 wt% of dipropylamine is used. The resist stripping solution 1 is charged in a stripping tank 2. ing. First, the resist stripper 1 is maintained at a temperature of 40 ° C., and the semiconductor substrate 3 on which the resist and the sidewall protective film are adhered is immersed in the resist stripper 1 for 4 minutes. Then, the resist adhering to the semiconductor substrate 3 is dissolved by the diethylene glycol monomethyl ether in the resist stripping solution 1 and is completely removed. It will be completely removed after being dissolved with propylamine.

Subsequently, the semiconductor substrate 3 from which the resist has been removed is transferred into a rinsing bath 4 which is a pressure-resistant container, and the inside of the rinsing bath 4 is sealed by using a rinsing bath lid 4a. And supercritical C adjusted to 100 atm at 40 ° C
The O ₂ gas 5 is injected into the rinsing bath 4, and the cleaning of the semiconductor substrate 3 for one minute using the supercritical CO ₂ gas 5 is repeated twice. The supercritical CO ₂ gas 5
The injection amount is preferably about 1 minute per internal volume of the rinsing tank 4, and the supercritical CO ₂ gas 5 adjusted to 100 atm at 40 ° C. is easy to produce. Can be easily supplied. Also, at 40 ° C, 100
When supercritical CO ₂ gas 5 adjusted to atmospheric pressure is used, the solubility of diethylene glycol monomethyl ether, which is the main component of resist stripper 1, is also 18.63 mol%.
And higher, since both a diffusivity and a high permeability supercritical CO ₂ gas 5, until the minute portions such as metal patterns formed on the semiconductor substrate 3 penetrates the supercritical CO ₂ gas 5 diffusion As a result, even the resist and the sidewall protective film adhered to these fine portions are washed out and accurately removed.

Further, when the cleaning using the supercritical CO ₂ gas 5 is completed, the pressure in the rinsing tank 4 is reduced, the rinsing tank lid 4a is opened, and the rinsing tank 4 is returned to the normal temperature and normal pressure state. Do that. Then, when the state returns to normal temperature and normal pressure, the supercritical CO ₂ gas 5 evaporates almost instantaneously and evaporates, and the semiconductor substrate 3 is dried without generating stains on the surface. Resulting in. In addition,
Since the supercritical CO ₂ gas 5 is almost harmless to living organisms, a facility for discharging the evaporated supercritical CO ₂ gas 5 is unnecessary. It has been confirmed by the inventors that the resist and the sidewall protective film are completely removed when the method of removing the resist and the sidewall protective film according to the above procedure is employed.

In order to further enhance the solubility of the resist stripping solution 1 according to the present embodiment, although not shown, a stripping tank different from the stripping tank 2 is provided, and diethylene glycol is used. The semiconductor substrate 3 may be washed with a resist stripping solution made of monomethyl ether. Then, in this case, the effect of rinsing the semiconductor substrate 3 by the supercritical CO ₂ gas 5 can be increased without bringing the resist and the sidewall prevention film into the rinsing bath 4. Further, a surfactant or the like may be added to the resist stripping solution 1 in advance, and further, the resist stripping solution 1 is neutralized with an acid such as hydrofluoric acid, an organic acid, or an amino acid. It is also possible to use it as it is, or to add and use tetramethylammonium or a salt thereof.

[0031]

As described above, since the resist stripping solution of the present invention contains a glycol ether solvent as a main component and contains an organic amine compound, the resist adhering to the substrate is dissolved and stripped. It is not only easily removed by washing with supercritical fluid
The property that the sidewall protective film made of the resist altered by dry etching can be completely removed after being stripped off together with the resist can be exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing a method for removing a resist and a side wall protective film according to the present embodiment.

[Explanation of symbols]

Reference Signs List 1 resist stripping liquid 3 semiconductor substrate (substrate) 5 supercritical CO ₂ gas (supercritical fluid)

Claims (6)

[Claims] 1. A resist stripper which dissolves and strips a resist and a side wall protective film attached to a substrate, and is removed by washing using a supercritical fluid, wherein the resist stripper contains a glycol ether-based solvent as a main component. A resist stripping solution characterized by containing an organic amine compound. 2. The resist stripping solution according to claim 1, wherein the content of the organic amine compound is in the range of 1 to 20 wt%. 3. The resist stripping solution according to claim 1, wherein the glycol ether solvent is diethylene glycol monomethyl ether. 4. The resist stripping solution according to claim 1, wherein the organic amine compound is an alkylamine or an alkylpropyldiamine. 5. The resist stripping solution according to claim 4, wherein the alkylamines are monopropylamine, dipropylamine, tripropylamine, diisopropylamine,
A resist stripping solution, which is any of dibutylamine. 6. The resist stripping solution according to claim 4, wherein the alkylpropyldiamine is 3- (methylamino)
A resist stripper, which is propylamine.