JPH01297645A - Negative type photoresist composition - Google Patents

Abstract

PURPOSE:To improve the transparent degree of the title composition at wavelength regions of a deep UV ray and an excimer laser and the alkaline development allowability of the composition by incorporating a copolymer which is introduced a group having an active carbon-carbon double bond against the deep UV ray and the excimer laser into the side chain of phenol contd. in a polyvinyl phenol, in the composition. CONSTITUTION:The copolymer contains constituting units shown by formulas I and II in a ratio of satisfying the formula 0.1<=[m/(m+k)]<=0.5 [wherein (m) is numbers of the constituting units shown by formula I, (k) is numbers of the constituting units shown by formula II]. In the formulas, R is a group having an active carbon-carbon double bond. Thus, the transparency of the composition in the wavelength regions of the deep UV ray and the excimer laser is improved, and the sensitivity, the resolution and the contrast of the composition are improved, and the alkaline development of the composition makes possible. The photoresist pattern of the composition with high accuracy is formed.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a photoresist composition suitable for forming a fine resist pattern, and more specifically to lithography using deep ultraviolet rays and excimer laser as a light source.
The present invention relates to a negative photoresist composition that has high sensitivity and resolution, and has excellent alkaline development tolerance. The negative photoresist composition of the present invention can be used in the electronic industry, such as being used for manufacturing high-density integrated circuits such as LSI and VLSI, and also for manufacturing photomasks used in their manufacture. Widely used in the field of

[Prior Art] In recent years, semiconductors have become increasingly highly integrated, and the demands for miniaturization are becoming more and more severe.

Therefore, in terms of manufacturing, it is becoming difficult to cope with conventional processes, and the introduction of new technologies is being considered. Efforts are being made to establish ultra-fine pattern processing technology by using deep ultraviolet rays with shorter wavelengths and excimer lasers instead of conventional ultraviolet rays as light sources used in lithography. Along with these changes in light sources, resists now have the conventional R resistance.
In addition to properties such as 1E property and heat resistance, the following properties are newly required.

b) High sensitivity to deep ultraviolet rays and excimer lasers.

Mouth) Excellent transparency in the deep ultraviolet region and excimer laser wavelength region.

c) High resolution.

A photosensitive composition prepared by mixing a vinylphenol homopolymer and a photosensitizer has been proposed as a negative photoresist that meets these requirements (Japanese Patent Publication No. 56-29261).
. However, although the polyvinylphenol used as a paste resin in these compositions has excellent transparency in the deep ultraviolet and excimer laser wavelength regions, the photosensitizer used together with these compositions has poor transparency after exposure, and furthermore, the alkali dissolution rate of polyvinylphenol is low. Since this is relatively fast, it is necessary to add a considerable amount of the above-mentioned photosensitizer in order to obtain a resist pattern with little film burr due to the alkaline phenomenon after exposure, and as a result, the transparency of the composition itself in this wavelength range is quite low. Become. Therefore, the cross section of the resist pattern obtained by development after exposure exhibits a strong inverted trapezoidal shape, and there is a problem in that it is not possible to resolve a fine pattern in which the side surfaces of the pattern are perpendicular to the substrate.

Furthermore, in order to solve the above problems, when the concentration of the photosensitizer in the composition is lowered, the sensitivity of the resist decreases and the solubility difference between exposed and unexposed areas becomes smaller, resulting in fine resist patterns. In order to obtain this, it is necessary not only to dilute the concentration of the developer, but also to maintain the temperature and development time of the developer very strictly. If set,
There has been a problem in that resist residues tend to occur in the cut-out pattern area, making it extremely difficult to set development conditions that will produce good results for both the cut-out pattern and the left-over pattern.

[Problems to be Solved by the Invention] As described above, it is difficult to say that conventional negative photoresist compositions are still practical in terms of transparency and development conditions.

Therefore, the present invention has been made to solve the above-mentioned problems, and the purpose of the present invention is to provide a negative that has high transparency in the deep ultraviolet and excimer laser wavelength ranges and has excellent alkaline development tolerance after exposure. An object of the present invention is to provide a type photoresist composition.

[Means for Solving the Problems] In view of the above circumstances, the present inventors have made extensive studies and have found that the phenol side chain of polyvinylphenol is injected with deep ultraviolet rays (250 to 300 nm) and excimer laser (
By introducing a group having a carbon-carbon double bond that is active toward 248, 308 nm), it is possible to change the conventional composition without impairing the transparency of polyvinylphenol in the deep ultraviolet and excimer laser regions. The amount of the photosensitive agent used can be significantly reduced or eliminated, resulting in a significant improvement in the transparency of the resist composition in this wavelength range, and at the same time, some of the phenolic OH groups can be It has been discovered that protection with the above-mentioned group makes it possible to reduce the alkali dissolution rate of the resist during development after exposure, and as a result, the setting range of alkaline development conditions is expanded and the tolerance of development conditions is improved. I was able to complete it. That is, the negative photoresist composition of the present invention comprises a structural unit represented by the following general formula (I), a copolymer containing a structural unit represented by the following formula (II), and an azide-based compound added as necessary. The present invention provides a negative photoresist composition comprising a photosensitizer.

The negative photoresist composition of the present invention will be explained in detail below.

The polymer used in the negative photoresist composition of the present invention is a copolymer having structural units represented by the above formulas (I) and (II). R in the general formula (I)
is a group having a carbon-carbon double bond that is active against deep ultraviolet rays (250 to 300 nm) and excimer laser (248,308 nm), and examples of such a group include -C-(- C) l = Cl-1yaO(,V) (in the formula, R' is a hydrogen atom or a methyl group, R'' is an alkylene group having 1 to 3 carbon atoms, and n is 011 or 2), and the like. Specifically, preferable examples include, but are not limited to, the following.Furthermore, in the copolymer, the group having the carbon-carbon double bond and the OH group are located at the ○-position with respect to the polyvinyl skeleton. Although it may be located at either the 1m-position or the p-position, the p-position is most preferred, followed by the m-position.

In addition, in the former copolymer, the ratio of the structural unit represented by formula (I) to the structural unit represented by formula (II) is as follows:
When the number of units I) is m1 and the number of structural units (II) is k, it is preferable that 0.1≦□≦0.5 m+. If this value is less than 0.1, it is undesirable because it adversely affects the sensitivity and development conditions of the resist, and if it exceeds 0.5, it is not preferred because the alkali solubility of the resist decreases.

Further, the copolymer has a weight average molecular weight ('τ) of 1.000 to 100 determined by gel permeation chromatography (GPC method) using monodisperse polystyrene as a standard.
．． 000, preferably 2,000 to 50,000. Outside the above range, sensitivity, resolution, heat resistance, film performance, adhesion to the substrate, etc. will be adversely affected.

In addition, since the negative photoresist composition of the present invention has a photosensitive group in the polymer itself constituting the composition,
Although it can be used alone as a photoresist composition, a photosensitizer can be added as necessary for the purpose of improving the sensitivity of the resist. Preferred examples of such photosensitizers include aromatic azide compounds and aliphatic azide compounds, and particularly preferred examples include aromatic azide compounds. Specifically, 4-
Azidobenzalacetophenone, 4-azidobenzal-
4'-Methoxyacetophenoenone, 4-azidobenzalacetone, 3-[4-(p-azidophenyl)-1°3-butadienyl]-5,5-dimethyl-2-cyclohexen-1-one, 3- (p-azidostyryl)-5,
5-dimethyl-2-cyclohexen-1-one, 1-azidopyrene, 4.4'-diazidochalcone, 2.6-bis(4'-azidobenthal)cyclohexanone, 1.3
-bis(4'-azidobenzal)-2-propanone, 1
．． 3-bis(4'-azidobenzal)-2-propanone-2'-sulfonic acid, 2,6-bis(4'-azidocinnamylidene)-4-methylcyclohexanone, 2,6-
Bis(4'-azidocinnamylidene)-4-methoxycyclohexanone, 2.6-bis(4'-azidocinnamylidene)-4-hydroxycyclohexanone, 2.6-
Bis(4'-azidocinnamylidene) cyclohexanone, 2,6-bis(4'-azidocinnamylidene) 4-hydroxymethylcyclohexanone, 2,6-bis(4'
-azidocinnamylidene) 4-trimethylsilylcyclohexanone, 2,6-bis(4'-azidocinnamylidene)cyclohexanone-4-carboxylic acid, 2,6-bis(4'-azidocinnamylidene)cyclo xanone-4
-sulfonic acid, 4,4'-diazidiphenylmethane,
4.4'-Diazidiphenyl ether, 4.4'-
Diazide benzophenone, 4.4'-diazido diphenyl sulfide, 4.4'-diazido diphenyl sulfone, 3.3'-diazido diphenyl sulfone, 4.4'-
diazido diphenyl, 4,4'-diazidostilbene,
2.2'-diazidostilbene, 4.4'-diazidodiphenylamine, 4.4'-diazidophenylazobenzene, 4.4'-diazidophenylazonaphthalene, 4
．． 4'-Diazidostilbene-2,2'-dicarboxylic acid, polyvinyl azidophthalate, azidobenzaldehyde-phenol resin, 4-azidodiphenylamine-2-
Carboxylic acid-formaldehyde resin, polyvinyl-p-
Examples include, but are not limited to, azidobenzal resin and the like. Further, these photosensitizers can be used alone or in combination of two or more.

The blending ratio of the copolymer and the photosensitizer is 0.1 part by weight or more and 20 parts by weight or less per 100 parts by weight of the copolymer. If it deviates from the above range, pattern shape and resolution will be adversely affected.

The negative photoresist composition according to the present invention is soluble in organic solvents, and when used in the production of integrated circuits, it is usually used in the form of a solution (resist solution). In this case, the composition is generally prepared by dissolving it in an organic solvent in a proportion of 1 to 50% by weight, preferably 5 to 30% by weight. In this case, the solvent to be used is one that uniformly dissolves each component of the negative photoresist composition of the present invention, and after coating the surface of a substrate such as silicon or aluminum, evaporates the organic solvent to create a uniform and smooth surface. It is preferable to use a coating film that can be obtained. Specifically, ketone solvents such as acetone, methyl ethyl ketone, cyclopentanone, and cyclohexanone, cellosolve solvents such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, and ether solvents such as tetrahydrofuran and diethylene glycol dimethyl ether. , ethylene glycol monoethyl ester, ethylene glycol monomethyl acetate, and other ester solvents, but are not limited thereto. The above organic solvents may be used alone or in combination of two or more.

In addition to the above-mentioned components, the negative photoresist composition of the present invention may also contain sensitizers, dyes, plasticizers, other resins, various inhibitors such as thermal reaction inhibitors, adhesion improvers, etc. You can.

With the negative photoresist composition of the present invention, a relief pattern can be formed by conventional photoresist techniques by adjusting the resist solution as described above. The method for forming this relief pattern will be explained below.

First, a resist solution prepared as described above is applied to a substrate. This application to the substrate can be performed using, for example, a spinner. This is then heated to a temperature of 60 to 120°C, preferably 80°C.
Dry at ~100°C for 20-60 minutes. After drying, the coated film is irradiated with deep ultraviolet rays and excimer laser through a negative photomask chart. Next, a relief pattern is obtained by washing away the unexposed areas with a developer.

As the developer, a weak alkaline aqueous solution of sodium hydroxide, potassium hydroxide, sodium metasilicate, tetramethylammonium hydroxide, etc., having a concentration of 5% by weight or less, can be used. The relief pattern thus formed has good resolution and contrast.

Furthermore, a substrate can be etched using the negative photoresist composition of the present invention and the pattern formed as described above as a mask.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Synthesis Example 1 12.0 g of polyvinylphenol with a molecular weight of about 6000 and 5.4 g of triethylamine were dissolved in 300 ml of THF, and a mixed solution of 2.7 g of acrylic acid chloride and 20 ml of THF was added to the solution at 10°C with stirring for 1 hour. dripped. After the dropwise addition was completed, the reaction solution was further stirred at room temperature for 5 hours, and then the reaction solution was diluted with 3% The precipitated polymer was collected by filtration.

This polymer was purified by repeating THF dissolution and water reprecipitation several times, and vacuum-dried at 80° C. for 6 hours to obtain the desired polymer AP-1 (12.6 g). The introduction rate of acrylate groups in this polymer was found to be 18% by elemental analysis.

Synthesis Example 2 12.0 g of polyvinylphenol with a molecular weight of about 6000 and 5.4 g of triethylamine were dissolved in 300 ml of THF, and a mixed solution of 5.4 g of acrylic acid chloride and 20 ml of THF was added to the solution at 10° C. while stirring well for 1 hour. dripped. After the dropwise addition was completed, the mixture was further stirred at room temperature for 5 hours, and then the reaction solution was added to three traces of water, and the precipitated polymer was collected by filtration.

This polymer was purified by repeating THF dissolution and water reprecipitation several times, and vacuum-dried at 80° C. for 6 hours to obtain the desired polymer AP-2 (13.6 g). The introduction rate of acrylate groups in this polymer was found to be 34% by elemental analysis.

Synthesis Example 3 12.0 g of polyvinylphenol with a molecular weight of about 6000 and 5.4 g of triethylamine were dissolved in 300 ml of THF, and a mixed solution of 7.4 g of acrylic acid chloride and 30 ml of THF was added to the solution at 10°C while stirring well for 1 hour. dripped. After the dropwise addition was completed, the mixture was further stirred at room temperature for 5 hours, and then the reaction solution was added to 3XZ of water, and the precipitated polymer was collected by filtration.

This polymer was purified by repeating THF dissolution and water reprecipitation several times, and vacuum-dried at 80° C. for 6 hours to obtain the desired polymer AP-3 (15.5 g). The rate of introduction of acrylate groups into this polymer was found to be 48% by elemental analysis.

Example 1 0 g of AP-1 obtained in Synthesis Example 1 was dissolved in 22 ml of ethyl cellolub acetate to prepare a resist solution. This resist solution was applied to a silicon wafer using a spin coater at 2,600 rpm, and then heated to 80°C for 40 min.
Prebaking was performed for 1 minute to obtain a coating of approximately 1.0 μm.

Next, this resist film was irradiated with light using a KrF excimer laser stepper. After irradiating with varying exposure doses, the film was developed by immersing it in a 2.3% tetramethylammonium hydroxide aqueous solution for 60 seconds, and then rinsing by immersing it in water for 30 seconds. The remaining film was plotted against the exposure dose. The sensitivity curve was defined as a sensitivity curve, and the exposure amount at which the residual film rate after development was 80% was defined as the sensitivity. The sensitivity of this resist was 220 mj. Furthermore, using this resist, a resist film with a thickness of 1 μm was formed on a silicon wafer in the same manner as above, and a 1 μm resist film was formed using a K r F excimer laser stepper through a chrome mask having a pattern.
15 reduction projection exposure was performed.

Further, this resist film was developed by treating it with a 2.3% aqueous solution of tetramethylammonium hydroxide (20° C.) for 60 seconds, and was washed with water for 30 seconds to form a resist pattern.

As a result of observing the pattern thus formed using an electron microscope, it was found that both the cutout pattern and the remaining pattern had good resolution of fine patterns of 0.5 μm without having steep cross-sectional profiles.

Example 2 A resist solution was prepared by dissolving 8.0 g of AP-2 obtained in Synthesis Example 2 in 22 ml of ethyl cellolub acetate. This resist solution was coated onto a silicon wafer using a spin coater at 2200 rpm, and prebaked at 80° C. for 40 minutes to obtain a coating of about 1.0 μm. Next, the sensitivity of this resist film was measured in the same manner as in Example 1, and it was found that it had a sensitivity of 196 mj.

Furthermore, using this resist, a resist pattern was formed on a silicon wafer in the same manner as in Example 1. As a result of observing the pattern thus formed using an electron microscope, it was found that both the cutout pattern and the remaining pattern had good resolution of fine patterns of 0.5 μm without having steep cross-sectional profiles.

Example 3 A resist solution was prepared by dissolving 8.0 g of AP-3 obtained in Synthesis Example 3 in 22 ml of ethyl cellolub acetate. This resist solution was coated onto a silicon wafer using a spin coater at 3200 rpm, and prebaked at 80° C. for 40 minutes to obtain a coating of about 1.0 μm. next,
The sensitivity of this resist film was measured in the same manner as in Example 1 and was found to have a sensitivity of 159 mj.

Furthermore, using this resist, a resist pattern was formed on a silicon wafer in the same manner as in Example 1. As a result of observing the pattern thus formed using an electron microscope, it was found that both the cut-out pattern and the remaining pattern had a good 0.05 mm cross-section without steep profiles. It was found that fine patterns of 5 μm could be resolved.

Example 4 AP-18.0g and 3.37-g obtained in Synthesis Example 1
A resist solution was prepared by dissolving 1.2 g of diacid diphenyl sulfone in 22 ml of ethyl cellolub acetate. This resist solution was coated onto a silicon wafer using a spin coater at a rotation speed of 31 degrees, and prebater was performed at 80° C. for 40 minutes to obtain a coating of about 1.0 μm. next,
The sensitivity of this resist film was measured in the same manner as in Example 1 and was found to have a sensitivity of 130 mj.

Furthermore, using this resist, a resist pattern was formed on a silicon wafer in the same manner as in Example 1. As a result of observing the pattern thus formed using an electron microscope, it was found that both the cutout pattern and the remaining pattern had good resolution of fine patterns of 0.5 μm without having steep cross-sectional profiles.

Comparative Example 1 AP-18.0g and 3.3'- obtained in Synthesis Example 1
A resist solution was prepared by dissolving 2.4 g of diazidodiphenylsulfone in 22 ml of ethyl cellolub acetate. This resist solution was coated onto a silicon wafer using a spin coater at 2,600 rpm, and prebaked at 80° C. for 40 minutes to obtain a coating of about 1.0 μm. next,
The sensitivity of this resist film was measured in the same manner as in Example 1 and was found to have a sensitivity of 113 mj.

Furthermore, using this resist, after forming a resist film with a thickness of 1 μm on a silicon wafer in the same manner as in Example 1,
After exposure, this resist film was diluted with a 2.3% aqueous solution of tetramethylammonium hydroxide (20℃) for 60 minutes.
It was processed for seconds, developed, and washed with water for 30 seconds to form a resist pattern. As a result of observing the pattern thus formed using an electron microscope, the cross-sectional shape of the pattern showed a strong inverse taper, and a fine pattern of 0.8 μm or less could not be resolved.

Comparative Example 2 Using the resist solution used in Comparative Example 1, a resist film with a thickness of 1 μm was formed on a silicon wafer in the same manner as in Example 1, and then exposed to light. Oxide 0.8% aqueous solution (
The resist pattern was developed by processing at 20'C) for 120 seconds and washing with water for 30 seconds to form a resist pattern. As a result of observing the pattern thus formed using an electron microscope, it was found that there was some development residue in the punched pattern area, and a fine pattern of 0.8 μm or less could not be resolved.

[Effects of the Invention] As explained above, the negative photoresist composition of the present invention has high transparency in the deep ultraviolet and excimer laser wavelength regions. As a result, sensitivity, resolution, and contrast can be significantly improved in lithography using the above-mentioned light beam as a light source, which is necessary for work to improve the resolution of resists.Furthermore, since the alkali developability is good,
There is no risk of pattern swelling or development residue, etc.
``It is possible to form a fine photoresist pattern with a high IHjlt. Therefore, the requirements for resolution of these compositions will become increasingly strict in the future.
In addition to being used as a resist for the production of high-density integrated circuits such as I and VLSI, it can also be used for the production of photomasks used in their production, and can be used in a wide range of fields in the electronics industry. .

Claims (2)

[Claims] (1) (A) The following general formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (R in the formula is a group having an active carbon-carbon double bond.) Units and the following formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (II) Contains the constituent units shown by the formula (I) and the ratio of the constituent units shown by the formula (II) is a copolymer such that 0.1≦m/(m+k)≦0.5, where m is the number of structural units (I) and k is the number of structural units (II), and (b) A negative photoresist composition containing an azide-based photosensitizer added as necessary. (2) The negative photoresist composition of the present invention is characterized in that the proportion of the azide photosensitizer added as necessary is 0.1 to 20 parts by weight based on 100 parts by weight of the copolymer. A negative photoresist composition according to claim 1.