JPH0824775A - Photoresist solution supply method - Google Patents

Abstract

PURPOSE:To improve coating property or the like by supplying the photoresist solution to a substrate after filtering with a filter composed of a polyalkene film to prevent the deterioration in removal efficiency of particles in filtration and supply of the photoresist solution. CONSTITUTION:In the supply of the photoresist solution, the photoresist solution is supplied to the substrate after filtered with the filter composed of the polyalkene film. And the polyalkene film is a polyethylene film or a polypropylene film. In this way, the deterioration in removal efficiency of the particles in the continuous filtration and supply of the photoresist solution is prevented and the improvement of photoresist coating property, the increase in production efficiency of the product of an element or the like and the decrease in the production cost are attained. Furthermore, the photoresist solution is an organic solvent composition obtained by dissolving a resin composition containing an alkali soluble resin, a quinon diazide group-containing compound and a surfactant. As a result, the coating film free from striation is constantly supplied on the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supplying a photoresist solution, and more particularly to a method for supplying a photoresist solution when continuously filtering and supplying it onto a substrate such as a silicon wafer.

[0002]

2. Description of the Related Art With the recent microfabrication of electronic parts, in the field of manufacturing electronic parts such as semiconductor elements and liquid crystal display elements, when supplying and applying a photoresist solution onto a substrate such as a silicon wafer, a minute amount of solution is applied. There is a growing demand for highly efficient and stable supply of a photoresist solution from which particles and the like have been removed. Therefore, at present, generally, the photoresist solution is filtered by a filter to remove fine particles and the like and then supplied onto the substrate.

As such a filter, a polytetrafluoroethylene membrane (PTFE) is used in view of stability and chemical resistance.
Membrane) has been used conventionally. However PTFE
In the membrane, as the amount of filtration and supply of the photoresist solution increases, the removal efficiency of fine particles gradually decreases, and the number of particles remaining in the photoresist solution after filtration increases, which adversely affects the product quality of elements and the like. There is a problem. In addition, the PTFE membrane is liable to cause filter clogging during continuous filtration / supply, and the filtration time per quart gradually becomes longer, resulting in lower product manufacturing efficiency such as elements and product quality deterioration due to defective photoresist coating. Cause problems. For this reason, the frequency of filter replacement must be increased, which causes a problem such as an increase in manufacturing cost.

On the other hand, the photoresist solution has been improved in order to cope with the recent microfabrication, and a photoresist solution containing a surfactant such as a fluorine-based surfactant is often used to prevent the occurrence of striation (coating unevenness). It has become possible to be. However, when a photoresist solution containing a surfactant is filtered through a PTFE membrane and continuously supplied onto the substrate, the surfactant is adsorbed on the PTFE membrane for a while after the filter is replaced, and the photoresist solution in the filtered photoresist solution is absorbed. However, there is also a problem that striations are likely to occur in the photoresist solution at the beginning of the supply onto the substrate because of the low content of the surfactant.

As a countermeasure against such a problem, conventionally, a means of flushing a few quarts of photoresist solution to the filter and discarding it is taken after the filter is replaced until the adsorption of the surfactant is saturated. , This is extremely inefficient and wasteful. On the other hand, instead of the photoresist solution, a method is proposed in which a filter is impregnated and saturated with the same solvent as the solvent of the photoresist solution added with an anti-striation agent (fluorine-based surfactant) before use. (JP-A-4-296013, etc.)
However, even in this method, there are problems such as an increase in the number of manufacturing steps and waste of the striation preventing agent. Furthermore, as a countermeasure from another point of view, the amount of the surfactant adsorbed on the filter is taken into consideration, and a photoresist solution containing a large amount of the surfactant in advance is used, so that the interface in the photoresist solution after filter filtration is increased. There is also a method in which the amount of activator is set to an appropriate amount for preventing striation. However, even in this case, there is a problem that striations occur as the continuous filtration / supply amount increases. That is, it is difficult to suppress the occurrence of striations by controlling the blending amount of the surfactant in the photoresist solution in continuous filtration / supply by any of the conventional methods, and the amount of the surfactant in the photoresist solution after filtration is difficult. It was impossible to continuously and stably supply the coating film having no striation on the substrate while keeping the temperature constant.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to prevent a decrease in particle removal efficiency in continuous filtration / supply of a photoresist solution, and While improving coating properties, increasing manufacturing efficiency of products such as elements, and reducing manufacturing cost, in photoresist solutions containing surfactants, coating films without striations are continuously and reliably formed on the substrate. Another object of the present invention is to provide a method for supplying a photoresist solution which can be supplied to

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, in the continuous supply of a photoresist solution onto a substrate, a polyalkene film was used as a filter for filtration. Found that the above problems can be solved by using
Based on this, the present invention has been completed.

That is, according to the present invention, there is provided a photoresist solution supply method characterized in that the photoresist solution is filtered on a filter made of a polyalkene film and then supplied onto a substrate.

The photoresist solution supply method of the present invention will be described in detail below.

The photoresist solution used in the present invention is
It is not particularly limited, and any conventional photoresist solution can be used, but an alkali-soluble resin and a quinonediazide group-containing compound are blended from the viewpoint of microfabrication, and further surface active from the viewpoint of striation prevention. A positive photoresist solution prepared by dissolving a resin composition containing an agent in an organic solvent is preferably used.

Examples of the alkali-soluble resin include alkali-soluble novolac resins, acrylic resins, copolymers of styrene and acrylic acid, polymers of hydroxystyrene, polyvinylphenol, poly-α-methylvinylphenol and the like. Among them, alkali-soluble novolac resins are particularly preferable. As the alkali-soluble novolak resin, those conventionally used as a film-forming substance in a positive photoresist solution,
For example, those obtained by condensing an aromatic hydroxy compound such as phenol, cresol and xylenol with an aldehyde such as formaldehyde in the presence of an acidic catalyst are preferably used, but the present invention is not limited thereto. As the alkali-soluble novolac resin, one having a weight average molecular weight of 2,000 to 20,000, preferably 5,000 to 15,000 with the low molecular weight region cut is preferably used.

The quinonediazide group-containing compound constitutes a photosensitive component, and includes, for example, sulfonic acids of quinonediazides such as orthobenzoquinonediazide, orthonaphthoquinonediazide, orthoanthraquinonediazide or functional derivatives thereof (eg, sulfonic acid chloride), and phenol. Particular or complete esterification, or partial or complete amidation with a compound having a neutral hydroxyl group or an amino group is specifically mentioned.

Examples of the compound having a phenolic hydroxyl group or an amino group include 2,3,4-trihydroxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone and 2,3,4,4'-. Polyhydroxybenzophenones such as tetrahydroxybenzophenone; 1- [1- (4-hydroxyphenyl) isopropyl] -4- [1,1-bis (4-hydroxyphenyl) ethyl] benzene; tris (4-hydroxyphenyl) ) Methane, bis (4-hydroxy-3,5-dimethylphenyl) -4-hydroxyphenylmethane, bis (4
-Hydroxy-2,5-dimethylphenyl) -4-hydroxyphenylmethane, bis (4-hydroxy-3,5
-Tris (hydroxyphenyl) methanes such as -dimethylphenyl) -2-hydroxyphenylmethane and bis (4-hydroxy-2,5-dimethylphenyl) -2-hydroxyphenylmethane or a methyl-substituted product thereof; bis (3-cyclohexyl) -4-hydroxyphenyl)-
3-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxyphenyl) -2-hydroxyphenylmethane, bis (3-cyclohexyl-4-hydroxyphenyl) -4-hydroxyphenylmethane, bis (5-cyclohexyl-4-) Hydroxy-2-methylphenyl) -2-hydroxyphenylmethane, bis (5-
Cyclohexyl-4-hydroxy-2-methylphenyl) -3-hydroxyphenylmethane, bis (5-cyclohexyl-4-hydroxy-2-methylphenyl)-
4-hydroxyphenylmethane, bis (3-cyclohexyl-2-hydroxyphenyl) -3-hydroxyphenylmethane, bis (3-cyclohexyl-2-hydroxyphenyl) -4-hydroxyphenylmethane, bis (3-cyclohexyl-2- Hydroxyphenyl) -2
-Hydroxyphenylmethane, bis (5-cyclohexyl-2-hydroxy-4-methylphenyl) -2-hydroxyphenylmethane, bis (5-cyclohexyl-2)
-Hydroxy-4-methylphenyl) -4-hydroxyphenylmethane and other tris (cyclohexylhydroxyphenyl) methanes or their methyl-substituted compounds; other compounds having a hydroxyl group or an amino group, such as phenol, phenol resin, p-methoxyphenol, Dimethylphenol, hydroquinone, bisphenol A, polyhydroxydiphenylalkane, polyhydroxydiphenylalkene, α, α ′, α ″ -tris (4-hydroxyphenyl) -1,3,5-triisopropylbenzene, naphthol, pyrocatechol, Pyrogallol, Pyrogallol monomethyl ether, Pyrogallol-1,3-
Dimethyl ether, gallic acid, esterified or etherified gallic acid leaving some hydroxyl groups, aniline, p
-Aminodiphenylamine and the like. Among them, polyhydroxybenzophenone and naphthoquinone-1,2-diazide-5-sulfonic acid or naphthoquinone-1,2-
A complete esterified product or a partially esterified product with diazide-4-sulfonic acid is preferable, and an average degree of esterification is 7
It is preferably 0% or more.

The organic solvent is preferably an organic acid ester solvent, and specific examples thereof include fatty acid alkyl or acetic acid ester of alkylene glycol or its monoalkyl ether. Examples of the fatty acid alkyl include methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, and the like, alkylene glycol or the like. Examples of acetic acid esters of monoalkyl ethers include ethylene glycol monoacetate, diethylene glycol monoacetate, propylene glycol monoacetate, monomethyl ether of dipropylene glycol monoacetate, monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether. To be These may be used alone or in combination of two or more.

Any conventional surfactant may be used as the surfactant, but a fluorine-based surfactant is most preferably used. For example, FC-430 (manufactured by Sumitomo 3M Limited), etc. Is specifically mentioned. The amount of this surfactant compounded in the resin composition depends on the surfactant used,
Although it varies depending on the resin composition, the organic solvent, etc., from the viewpoint of the striation prevention effect, for example, when a fluorine-based surfactant is used, the resin composition (that is, the component obtained by removing the organic solvent component from the photoresist solution) is used. 150 to
It is preferable to mix them so that the concentration is in the range of 600 ppm. If it deviates from this range, it is difficult to obtain a sufficient striation prevention effect.
It is particularly preferable that the concentration is in the range of pm. When the photoresist solution containing the above-mentioned amount of the fluorine-containing surfactant is filtered through a filter (described later) composed of a polyalkene film and continuously supplied onto the substrate, even if the supply amount increases, the striation It is possible to continuously and stably supply a coating film without a charge onto the substrate.

If necessary, the photoresist solution may further contain various additives such as sensitizers and colorants which are conventionally used conventionally.

The filter used in the present invention is composed of a polyalkene film, and specifically, a polyethylene film and a polypropylene film are typical examples. The structure of the filter is not particularly limited, and any type conventionally used can be used, and not only the membrane structure but also a hollow fiber structure or the like can be used. Among them, those having an asymmetric fine structure are preferably used. Asymmetric fine structure is the filter inlet (i
The hole diameters on the n-let side and the out-let side are not the same, and the hole diameter on either side is larger than the hole diameter on the other side. -The let side has a relatively small pore size, and particles and the like are sequentially filtered according to the particle size, so that efficient removal can be performed. Although the pore size of the filter is not particularly limited, a filter having a pore size of about 0.1 μm (pore size) usually used for filtering a photoresist solution is used.

By filtering with a filter made of a polyalkene film, even when a photoresist solution containing a surfactant for preventing striation is used, the photoresist solution is continuously supplied onto the substrate after filtration. Even in this case, the striation prevention effect is stably maintained, and the photoresist characteristics are not adversely affected. It is speculated that this is because the polyalkene film does not adsorb the surfactant. That is, as described above, for example, striation control is performed by defining the compounding amount of the fluorine-based surfactant with respect to the resin composition so that the concentration is in the range of 150 to 600 ppm, more preferably 200 to 500 ppm. Therefore, when the photoresist solution is filtered through the polyalkene film and then continuously supplied onto the substrate, a coating film without striation can be continuously and stably formed on the substrate even if the supply amount increases. It can be reliably supplied.

As described above, after the photoresist solution is filtered through the polyalkene membrane by the photoresist supply method according to the present invention, the uniform photoresist solution supplied on the substrate is
By heating, a photoresist layer having a predetermined thickness is formed on the substrate. Then, the substrate on which the photoresist layer is formed is subjected to exposure, development, heat treatment and the like to obtain a substrate on which a fine photoresist pattern is formed.

Examples of the present invention will be described below, but the present invention is not limited thereto. Note that the filter has an asymmetrical fine structure and
The one with a relatively large diameter on the let side was used.

[0021]

Example 1 23 parts by weight of cresol novolac resin, 7 parts by weight of naphthoquinonediazide compound, and a fluorosurfactant (FC-
430; 0.012 parts by weight (corresponding to 400 ppm) of Sumitomo 3M Ltd. was added, and butyl acetate 6
It was dissolved in a mixed organic solvent of 3 parts by weight and 7 parts by weight of ethyl lactate to prepare a positive photoresist solution.

Next, 15 quarts of the positive type photoresist solution prepared in this way was continuously added to each one quart to form a polyethylene (PE) film (pore size 0.1 μm).
Through a filter (CWUV0SIS3; manufactured by Nippon Millipore Co., Ltd.) as a filtration membrane under nitrogen pressure of 0.4 kg / cm ² to remove particles (particle diameter of 0.1 μm or more).

FIG. 1 shows the results of examining the filtration amount and filtration time for each quart of the positive photoresist solution thus obtained. The results of examining the number of particles (particles / ml) in this positive photoresist solution are shown in FIG.

Next, each positive type photoresist solution obtained by continuously filtering 1 quart of the above is
After spin coating on an inch silicon wafer at 3000 rpm for 20 seconds to form a coating film having a thickness of 1.3 μm, the surface condition was observed, and the in-plane film thickness of all coating films was uniform. , No occurrence of striation was confirmed.

Example 2 Instead of the filter made of PE membrane used in Example 1,
Hollow fiber polypropylene (PP) membrane (pore size 0.1
The results of examining the relationship between the filtration amount and the filtration time for each quart and the number of particles by the same operation as in Example 1 except that a filter (μm) (manufactured by Kitz Corporation) was used. 1 and FIG.

Further, as a result of examining the occurrence of striation by the same operation as in Example 1, it was confirmed that all the coating films had a uniform in-plane film thickness and the occurrence of striation was not confirmed.

Example 3 In the positive photoresist solution used in Example 1,
The amount of the fluorine-based surfactant added is 0.0045 parts by weight (1
The occurrence of striation was examined by the same operation as in Example 1 except that the positive photoresist solution prepared by the same operation as in Example 1 was used except that the amount was changed to 50 ppm). As a result, it was confirmed that the in-plane film thickness of the coating film was partially non-uniform and partial striation occurred, but there was no problem in practical use.

Example 4 In the positive photoresist solution used in Example 1,
The compounding amount of the fluorine-based surfactant is 0.006 parts by weight (20
(Corresponding to 0 ppm) except that a positive photoresist solution prepared by the same operation as in Example 1 was used,
Generation of striation was examined by the same operation as in Example 1. As a result, the in-plane film thicknesses of all the coating films were uniform, and no striation was confirmed.

Example 5 In the positive photoresist solution used in Example 1,
The content of the fluorine-based surfactant is 0.015 parts by weight (50
(Corresponding to 0 ppm) except that a positive photoresist solution prepared by the same operation as in Example 1 was used,
Generation of striation was examined by the same operation as in Example 1. As a result, the in-plane film thicknesses of all the coating films were uniform, and no striation was confirmed.

Example 6 In the positive photoresist solution used in Example 1,
The compounding amount of the fluorine-based surfactant is 0.018 parts by weight (600
The occurrence of striation was examined by the same operation as in Example 1 except that the positive photoresist solution prepared by the same operation as in Example 1 was used, except that it was replaced with (corresponding to ppm). As a result, it was confirmed that the in-plane film thickness of the coating film was partially non-uniform and partial striation occurred, but there was no problem in practical use.

Example 7 The occurrence of striation was examined in the same manner as in Example 1 except that the filter used was replaced with the hollow fiber PP membrane used in Example 2. As a result, a part of the in-plane film thickness of the coating film was non-uniform and partial striation was confirmed, but there was no practical problem.

Example 8 In Example 4, the occurrence of striation was examined by the same operation as in Example 1 except that the filter used was replaced by the hollow fiber PP membrane used in Example 2. As a result, the in-plane film thicknesses of all the coating films were uniform, and no striation was confirmed.

Example 9 The occurrence of striation was examined in the same manner as in Example 1 except that the filter used was replaced by the hollow fiber PP membrane used in Example 2. As a result, the in-plane film thicknesses of all the coating films were uniform, and no striation was confirmed.

Example 10 In Example 6, the occurrence of striation was examined by the same operation as in Example 1 except that the filter used was replaced by the hollow fiber PP membrane used in Example 2. As a result, a part of the in-plane film thickness of the coating film was non-uniform and partial striation was confirmed, but there was no practical problem.

COMPARATIVE EXAMPLE 1 Except that the filter used in Example 1 was replaced with a filter (DFA4201FTE; manufactured by Nippon Pall Ltd.) using a polytetrafluoroethylene (PTFE) membrane (pore size 0.1 μm) as a filtration membrane. Particles were removed by the same operation as in Example 1.

FIG. 1 shows the results of examining the filtration amount and filtration time for each quart of the positive photoresist solution thus obtained. The results of examining the number of particles (particles / ml) in this positive photoresist solution are shown in FIG.

As is clear from the results shown in FIG. 1, Comparative Example 1
Filtration time with the PTFE membrane was 7 minutes at the 1st quart, but it took about 12 minutes at the 15th quart. On the other hand, the filtration with the PE membrane of Example 1 was 1
If the filtration time for quart eyes is less than 7 minutes, it will take 8 minutes for 15 quarts. Further, the filtration with the PP membrane of Example 2 took about 6 minutes and 30 seconds even when the filtration time at the 1st quart was 6 minutes and at the 15th quart, which was almost unchanged. That is, Examples 1 and 2 have less clogging of the filter and the like as compared with Comparative Example 1, the frequency of replacement of the filter is less, and it is advantageous in terms of manufacturing cost. In addition, the coating property on the substrate becomes better.

As is clear from the results of FIG. 2, the removal rate of particles by the PTFE film of Comparative Example 1 is 1 to
Although it gradually decreased over 15 quarts, P of Example 1
The particle removal rate by the E film and the PP film of Example 2 is
Almost no decrease in removal rate was observed at 1 to 15 quarts. That is, according to the supply methods of Examples 1 and 2, it is possible to manufacture products having excellent coatability and manufacturing efficiency as compared with the case of using the method of Comparative Example 1.

Then, in the same manner as in Example 1, each positive photoresist solution was spin-coated on a 6-inch silicon wafer at 3000 rpm for 20 seconds to form a coating film having a thickness of 1.3 μm. The surface state was observed, and the in-plane film thickness of the coating film obtained from the 6 to 15 quart filtered portion was uniform, and the occurrence of striation was not confirmed, but it was obtained from the 1 to 5 quart filtered portion. The in-plane film thickness of the coating film was not uniform, and striation was confirmed, which was not suitable for practical use.

Comparative Example 2 The occurrence of striation was examined by the same operation as in Example 1 except that the positive photoresist solution of Example 3 was used and the filter used was replaced with the PTFE membrane used in Comparative Example 1. As a result, the in-plane film thickness of the coated film obtained from the 14 to 15 quart filtered portion was uniform and no striation was confirmed, but the in-plane film of the coated film obtained from the 1 to 13 quart filtered portion was not confirmed. The thickness was not uniform and striation was confirmed, which was not suitable for practical use.

Comparative Example 3 The occurrence of striation was examined by the same operation as in Example 1 except that the positive photoresist solution of Example 4 was used and the filter used was the PTFE membrane used in Comparative Example 1. As a result, the in-plane film thickness of the coated film obtained from the 9 to 15 quart filtered portion was uniform and no striation was confirmed, but the in-plane film of the coated film obtained from the 1 to 8 quart filtered portion was not confirmed. The thickness was not uniform and striation was confirmed, which was not suitable for practical use.

Comparative Example 4 The occurrence of striation was examined by the same operation as in Example 1 except that the positive photoresist solution of Example 5 was used and the filter used was replaced with the PTFE membrane used in Comparative Example 1. As a result, the in-plane film thickness of the coating film obtained from 5 to 15 quart filtration was uniform and no striation was confirmed, but the in-plane film of the coating film obtained from 1 to 4 quart filtration was confirmed. The thickness was not uniform and striation was confirmed, which was not suitable for practical use.

Comparative Example 5 The occurrence of striation was examined by the same operation as in Example 1 except that the positive photoresist solution of Example 6 was used and the filter used was replaced with the PTFE membrane used in Comparative Example 1. As a result, the in-plane film thickness of the coating film obtained from the 4 to 15 quart filtration portion was uniform and no striation was confirmed, but the in-plane film of the coating film obtained from the 1 to 3 quart filtration portion was not confirmed. The thickness was not uniform and striation was confirmed, which was not suitable for practical use.

[0044]

As described above in detail, according to the present invention, it is possible to prevent a decrease in particle removal efficiency in continuous filtration and supply of a photoresist solution, improve photoresist coatability, and improve manufacturing efficiency of products such as devices. In the photoresist solution containing a surfactant, the coating film without striation is continuously formed on the substrate by defining the amount of the surfactant in the photoresist solution after filtration. It is possible to provide a method for supplying a photoresist solution that can be stably and reliably supplied to the method.

[0045]

[Brief description of drawings]

[0046]

FIG. 1 shows the continuous filtration and supply of photoresist solution.
It is a graph which shows the filtration time and the filtration amount for every quart.

[0047]

FIG. 2 In continuous filtration / supply of photoresist solution,
It is a graph which shows the number of particles in the filtrate for every quart.

Claims (5)

[Claims] 1. A method for supplying a photoresist solution, which comprises filtering the photoresist solution through a filter made of a polyalkene film and then supplying the photoresist solution onto a substrate. 2. The photoresist solution supply method according to claim 1, wherein the polyalkene film is a polyethylene film or a polypropylene film. 3. The photoresist solution is an organic solvent solution in which a resin composition containing an alkali-soluble resin, a quinonediazide group-containing compound and a surfactant is dissolved.
Alternatively, the method of supplying a photoresist solution according to 2 above. 4. The photoresist solution supply method according to claim 3, wherein the surfactant is a fluorine-based surfactant. 5. A fluorochemical surfactant is added to the resin composition in an amount of 1: 1.
The photoresist solution supply method according to claim 4, wherein the photoresist solution is contained at a concentration of 50 to 600 ppm.