JPH0367258B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a resist material used for forming fine patterns necessary for manufacturing semiconductor devices, magnetic bubble devices, optical application parts, etc. In recent years, semiconductor integrated circuits are becoming increasingly finer, and the resists used therein are also required to have higher resolution. That is, there is a need for a resist that can form fine patterns with a width of 0.5 to 2 μm with high accuracy. At the same time, the semiconductor industry continues to expand its market, and it is considered essential that semiconductor integrated circuits can be mass-produced in a short period of time. A microfabrication technique conventionally used in the technical field of semiconductor integrated circuits is ultraviolet lithography using photoresist. Ultraviolet lithography is a very effective method in that it can mass-produce semiconductor integrated circuits in a short period of time, but it has the disadvantage that it is susceptible to interference and diffraction because it uses light with a wavelength of approximately 350 nm or more. In terms of resolution, it is becoming increasingly difficult to meet the above requirements. Now, as a means of obtaining high resolution, X-ray lithography and electron beam lithography, which avoid optical systems susceptible to interference and diffraction, are currently being considered, but let's consider the resist exposure equipment used in these methods. As for X-ray exposure equipment, the development of X-ray sources has been a major hindrance in practical use, and for electron beam lithography equipment, it takes a long time to draw the resist coated on the substrate, so it is difficult to Although some parts are being put into practical use, it is thought that further improvements to electron beam lithography equipment are needed before it can be used for general purposes.
It is said that it is necessary to improve the lithography equipment rather than the resist material used. For the above reasons, it is still more effective to use ultraviolet lithography for semiconductor integrated circuit manufacturing. By the way, when we look at resist materials used in ultraviolet lithography, typical negative photoresists include compositions that combine cyclized rubber and aromatic azide compounds. 2,6-bis(4′-azidobenzal)-4-methylcyclohexanone,
Azidobenzalketones such as 2,6-bis(4'-azidobenzal)cyclohexanone and the like have been used. The sensitive wavelength range of these negative photoresists ranges from 300 to 300, depending on the aromatic azide compound used.
The wavelength is 450 nm, and since light interference and diffraction are noticeable in this region, the resolution of photoresist is said to be limited to 1.5 μm. If a material sensitive to shorter wavelengths can be found, resolution will improve. In addition, in the negative photoresist that is a combination of cyclized rubber and an aromatic azide compound, the developing solution that dissolves the uncured portions swells the cured resist during development after curing with ultraviolet rays. It can cause swelling and lines. In addition to light interference and diffraction, the swellability of the resist itself to the developing solution is considered to be a major factor in reducing resolution. On the other hand, when looking at positive photoresists,
A typical photoresist is a combination of a novolak resin and a quinonediazide compound, and some modified 0-naphthoquinonediazide based photoresists are used as photosensitive materials. Positive photoresists generally have good resolution, but the base resin used is an organic material such as novolac resin, while the developer is an alkaline aqueous solution, so the resin part swells during development. This is said to be because only the ultraviolet irradiated portion dissolves. However, the sensitive wavelength range of conventional positive photoresists is 300 to 500 nm, which is the same as that of negative photoresists in order to achieve high sensitivity.
However, it has the disadvantage that it is susceptible to light interference and diffraction, resulting in a decrease in resolution. An object of the present invention is to provide a photosensitive resin composition that eliminates the drawbacks of the conventional photoresists described above, has a short curing time (hereinafter referred to as good sensitivity), and forms positive images with high resolution. As a result of intensive studies to achieve the above objective, we found that (a) novolac resin (homocondensation or cocondensation product) or polyhydroxystyrene resin (homopolymer or copolymer) or a mixture thereof; and (b) general formula (However, Y is

【formula】

【formula】

[Formula] R ¹ represents lower alkylene, aminoalkylene, Z represents -NR ² ₂ , -OR ² (however, R ² represents hydrogen or a lower alkyl group), and N ₃ - represents -Y
-R ¹ Located in the para or meta position relative to Z. It has been found that a photosensitive resin composition characterized by comprising a compound represented by the following formula gives good results in terms of both sensitivity and resolution. The present invention will be explained in detail below. As mentioned above, one of the causes of a decrease in the resolution of a photoresist is due to the base resin used. In the present invention, the base resin used may be a novolac resin with low swelling property (herein, it means a condensate of formaldehyde and carbolic acid, cresol, or other alkylphenol) or a polyhydroxystyrene resin. Novolac resins can be used in the form of homo-condensates or co-condensates, and polyhydroxystyrene resins can also be used in the form of homopolymers or copolymers (hereinafter referred to as novolac resins and polycondensates). encased in hydroxystyrene resin). These may be used alone or in the form of a mixture of both. Novolac resins and polyhydroxystyrene resins can be obtained as commercial products. For example, examples of the novolac resin include carbolic acid novolac resin, cresol novolac resin, and carbolic acid/cresol novolac resin, and examples of the polyhydroxystyrene resin include polyparavinylphenol. The molecular weight, cocondensation composition ratio, and copolymerization composition ratio of these base resins can be arbitrarily changed depending on the purpose. The base resin used needs to be formed into a film at the temperature used as a photoresist, for example 10 to 100°C, and for this reason, it is preferable to have a number average molecular weight of 500 or more, and to have good heat resistance as a photoresist. Considering that the number average molecular weight is
1000 or more is desirable. The second cause of the reduction in resolution of photoresists can be attributed to light interference and diffraction phenomena, as described above. Therefore, in order to obtain high resolution, this effect must be minimized in the short wavelength region (the short wavelength region here refers to the region of 200 to 360 nm, and the long wavelength region refers to the region of 360 nm).
Indicates m or more. ) must be exposed to light. In the case of the photosensitive resin composition of the present invention, its photosensitivity is attributable to the photoreactivity of the aromatic azide group or aromatic sulfonyl azide compound represented by the general formula [].
In other words, the active species nitrene generated from the photo-excited [] reacts with the base resin and causes the base resin to become insolubilized in an alkaline solution, resulting in a difference in solubility in the developer (alkaline solution) between the exposed and unexposed areas. This makes it possible to form a pattern. Therefore, in order to set the photosensitive wavelength range to a short wavelength range, it is necessary to position the maximum absorption wavelength of the compound represented by the general formula [] in the short wavelength range, but the compound represented by the general formula [] has a structural is satisfied with this request. In other words, in addition to the benzene ring, there is only one group represented by Y as a structural unit of the structure that is conjugated with an aromatic azide group to form one chromophore, and these influence the maximum absorption range of the chromophore. Even when looking at compounds having a carbonyl group, amide group, or ester group, which are considered to have the greatest effect on the conjugation effect, their maximum absorption is at short wavelengths. In fact, the maximum absorption of a compound having the above group is paraazidophenyl 2 where Y is a carbonyl group.
-(N,N-dimethylamino)ethyl ketone is
287 nm (molar absorption number 16000), 2-(N,N-dimethylamino)ethyl paraazidobenzoate where Y is an ester group is 274 nm (molar absorption number
16000), N,N-dimethyl- where Y is an amide group
N′-paraazidobenzoylethylenediamine is
270 nm (molar absorption number 17,000), and 2-(N,N-dimethylamino)ethyl metaazidobenzoate, in which Y is an ester group and the azide group is substituted at the meta position, is 253 nm (molar absorption number 18,000). Almost all of the aromatic azide compounds represented by the general formula [] have maximum absorption in the short wavelength region of ultraviolet light of at least 290 nm or less. As detailed above, the aromatic azide compound used in this system has a para-azidobenzalketone skeleton, which is used in conventional photoresists, and has maximum absorption in the long wavelength region around 360 nm. Since it has a maximum absorption in the short wavelength region of 290 nm or less compared to other materials, the sensitive wavelength region also becomes a short wavelength region, and the cause of resolution decline due to diffraction and interference is improved, resulting in a sufficient improvement in resolution. It became. For a photosensitive material, its photosensitivity as well as its resolution are important characteristics, and especially when mass production is considered, it is impossible to improve resolution at the expense of sensitivity. This material has greatly improved resolution, and at the same time maintains high sensitivity comparable to conventional high-sensitivity negative photoresists. The photosensitizer component of this material not only has an aromatic azide group as a photosensitive group, which is extremely sensitive to light and has a reputation for its high efficiency of photoreactivity, but other features have also been added. ing. When considering the photoreaction of aromatic azide compounds, it is found that the sensitivity as a photosensitizer depends on the photodegradability efficiency of the azide group and the reactivity efficiency of its decomposition product, active nitrene, with the base resin component. Among these, the distance between the reaction points (the closer they are, the higher the efficiency) is one of the governing factors, and it is therefore considered to be correlated with the compatibility between molecules. Nagamatsu et al. also touched on this point in their discussion of the sensitizing efficiency of sensitizers (Nagasue, Inui, Photosensitive Polymer P172 (1977) Kodansha). Therefore, it is important to increase the compatibility between the base resin and the aromatic azide compound.
This is a method of increasing sensitivity. In addition to the polar substituent represented by Y, the aromatic azide compound used in the present invention has a polar substituent group at the end of the molecule, such as a hydroxyl group or an amino The group is introduced to achieve this purpose. For this reason, the coating film was homogeneous and had a high sensitivity suitable for practical use. Examples of the aromatic azide compound or aromatic sulfonyl azide compound used in the photosensitive resin composition of the present invention include para (or meta) azidobenzoic acid 2-
(N,N-dimethylamino)ethyl, para (or meta)azidobenzoic acid 3-(N,N-dimethylamino)propyl, and other benzoic acid ester-based aromatic azide compounds having an amino group at the molecular end; Para (or meta)azide Benzoic acid ester aromatic azide compound with a hydroxyl group at the molecular end, represented by 2-hydroxyethyl benzoate, N,N-
Dimethyl-N'-para (or meta)azidobenzoylethylenediamine, N,N-dimethyl-
Benzoic acid amide aromatic azide compounds such as N'-para (or meta)azidobenzoylpropylene diamine, aromatic compounds such as para (or meta)azidophenyl 2-(N,N-dimethylamino)ethyl ketone, etc. Examples include, but are not limited to, ketone aromatic azide compounds, benzoic acid ester sulfonyl azide compounds represented by para (or meta) sulfonyl azide 2-(N,N-dimethylamino)ethyl benzoate, and the like. The aromatic azide compound or aromatic sulfonyl azide compound exemplified above is synthesized, for example, by the method shown below. A benzoic acid ester aromatic azide or sulfonyl azide compound having an amino group at the molecular end is reacted with the corresponding azide or sulfonyl azide benzoic acid chloride and N,N-dialkylaminoalkanol to produce the hydrochloride of the target compound, It can be obtained by treating this with an alkali such as sodium hydroxide. A benzoic acid ester aromatic azide compound having a hydroxyl group at the molecular end can be obtained by reacting the corresponding azide benzoic acid chloride with a large excess of alkylene diol in the presence of an organic base such as pyridine or triethylamine. Benzoic acid amide aromatic azide compounds are synthesized by reacting the corresponding azide benzoic acid chloride with N,N-dialkylaminoalkylene diamine to produce the hydrochloride of the target compound, and then treating this with an alkali. Ru. Para (or meta)azidophenyl 2-(N,N-dimethylamino)ethyl ketone is synthesized by Mannich reaction of azidoacetophenone with paraformaldehyde and dimethylamine hydrochloride. The blending ratio of the base resin and the aromatic azide compound of the photosensitive resin composition of the present invention is that when the base resin is 100 parts by weight, the aromatic azide compound is
It is preferably used in a range of 0.5 parts by weight to 150 parts by weight, more preferably in a range of 2 parts by weight to 100 parts by weight. If the amount is less than this range, the photosensitivity may not be sufficient for practical use, and if the amount is more than this range, the film forming ability may deteriorate significantly. many. The photosensitive resin composition of the present invention is applied to the surface of a suitable substrate in the form of a solution dissolved in a suitable organic solvent.
Therefore, the solvent used must be able to dissolve all of the components of the photosensitive resin composition, such as acetone,
For these purposes, solvents such as ketones such as methyl ethyl ketone and cyclohexanone, cellosolves such as methyl cellosolve, ethyl cellosolve, and ethyl cellosolve acetate, and esters such as ethyl acetate and butyl acetate can be used. Each of these components may be used alone, or two or more of them may be used in a mixed system. The blending ratio of the solvent is 100 to 100 parts by weight of the resin composition consisting of the resin component and the compound represented by the general formula [].
It is desirable to add 10,000 parts by weight. In addition to the base resin and the aromatic azide or sulfonyl azide compound represented by the general formula [], the photosensitive resin composition of the present invention may further contain secondary components depending on the purpose.
Examples of these include thermal polymerization inhibitors to measure storage stability, antihalation agents to prevent halation from the substrate, adhesion improvers to improve adhesion to the substrate, dyes, pigments, fillers, Examples include flame retardants and sensitizers. Next, a method for forming a pattern using the photosensitive resin composition of the present invention will be explained. Methods for applying the photosensitive resin composition to the supporting substrate include spin coating using a spinner, dipping, spraying,
Means such as printing are possible and can be selected as appropriate depending on the purpose. After application, apply at an appropriate temperature (120
℃ or below) to form a film. The coating film thickness can be adjusted by the coating means, the solid content concentration of the solution, and the viscosity. A relief pattern can be obtained by irradiating the photosensitive resin composition, which has become a coating film on a supporting substrate, with ultraviolet rays locally through a photomask, and then dissolving and removing the unexposed areas with a developer. can. Although pattern formation is possible using both contact and projection exposure methods, since the photosensitive resin composition of the present invention has a photosensitive region in the short wavelength range as described above, quartz can be used as a photomask base material. As an irradiation source, a material with high transmittance of short wavelength light such as
It is desirable to use a lamp with strong emission intensity in a short wavelength range, such as a Xe-Hg lamp. The photosensitive resin composition of the present invention can be developed with an alkaline solution as described above. Examples of these alkaline developing solutions include aqueous solutions of tetraalkyl ammonium hydroxide typified by tetramethylammonium hydroxide, aqueous solutions using inorganic alkalis typified by tertiary sodium phosphate, sodium hydroxide, etc. Any alkaline solution may be used and the solution is not limited to these. Development can be carried out by methods such as immersion and spray development. The present invention will be explained below by way of examples. still,
Parts in the examples indicate parts by weight. Example 1 10 parts of carbolic acid novolak resin and 1 part of 2-hydroxyethyl paraazidobenzoate were added to cyclohexanone.
A solution of the photosensitive resin composition was prepared by dissolving 90 parts of the photosensitive resin composition, and this solution was further pressure-filtered using a 0.2 μm pore filter. The obtained solution was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes to form a 0.8 μm layer.
A thick coating film was obtained. This coating film was closely covered with a striped quartz photomask and irradiated with ultraviolet light for 5 seconds from a distance of 30 cm using a 500WXe-Hg lamp. 0.15
It was developed using a specified potassium hydroxide aqueous solution and then washed with water to obtain a relief pattern with sharp edges. In this example, a fine repeating pattern with a minimum width of 1 μm could be formed. Example 2 10 parts of cresol novolak resin, 2-(N,N-dimethylamino)ethyl paraazidobenzoate
A photosensitive resin composition solution was prepared by dissolving 120 parts of ethyl cellosolve acetate, and this solution was filtered under pressure using a 0.2 μm pore filter. The obtained solution was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes to form a 0.9 μm layer.
A thick coating film was obtained. This coating film was irradiated with ultraviolet rays for 5 seconds under exactly the same conditions as in Example 1, developed using a 0.1N aqueous sodium hydroxide solution, and then washed with water to obtain a sharp relief pattern on the end surface. In this example, a fine repeating pattern with a minimum width of 1 μm could be formed. Example 3 10 parts of polyparavinylphenol, 3 parts of 2-(N,N-dimethylamino)ethyl metaazidobenzoate
A photosensitive resin composition solution was prepared by dissolving 120 parts of ethyl cellosolve acetate, and this solution was filtered under pressure using a 0.2 μm pore filter. The obtained solution was spin-coated onto a ceramic substrate whose surface had been polished flat using a spinner, and then heated at 70°C.
After drying for 20 minutes, a coating film with a thickness of 1.0 μm was obtained. This coating film was irradiated with ultraviolet light for 5 seconds under the same conditions as in Example 1, and tetramethylammonium hydroxide was
It was developed using a 0.2N aqueous solution and then washed with water to obtain a sharp relief pattern on the edge surface. In this example, a fine repeating pattern with a minimum width of 1.5 μm could be formed. Example 4 A solution of a photosensitive resin composition was prepared by dissolving 10 parts of carbolic acid novolak resin and 3 parts of N,N-dimethyl-N'-paraazidobenzoylethylenediamine in 60 parts of methyl cellosolve acetate, and this solution was further diluted with 0.2 parts of methyl cellosolve acetate. Pressure was applied using a μm pore filter. The obtained solution was spin-coated onto a silicon wafer using a spinner to obtain a coating film with a thickness of 0.8 μm. This coating film was irradiated with ultraviolet light for 5 seconds under the same conditions as in Example 1, and tetramethylammonium hydroxide was
It was developed using a 0.2N aqueous solution and then washed with water to obtain a sharp relief pattern on the edge surface. In this example, a fine repeating pattern with a minimum width of 1.0 μm could be formed. Example 5 10 parts of carbolic acid novolac resin, 5 parts of paraazidophenyl 2-(N,N-dimethylamino)ethyl ketone were mixed with 60 parts of cyclohexanone, ethyl cellosolve.
A solution of the photosensitive resin composition was prepared by dissolving it in a mixed solution consisting of 40 parts, and this solution was further pressure-filtered using a 0.2 μm pore filter. The obtained solution was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes.
A coating film with a thickness of 0.9 μm was obtained. This coating film was irradiated with ultraviolet light for 10 seconds under the same conditions as in Example 1, developed using a 0.1N aqueous solution of tetramethylammonium hydroxide, and then washed with water to obtain a sharp relief pattern on the edge surface. In this example, the minimum
A fine repeating pattern with a width of 1 μm could be formed. Example 6 A solution of a photosensitive resin composition was prepared by dissolving 10 parts of polyparavinylphenol and 2 parts of 3-(N,N-dimethylamino)propyl paraazidobenzoate in 100 parts of ethyl cellosolve acetate. was subjected to pressure filtration using a 0.2 μm pore filter. The resulting solution was spin-coated onto a silicon wafer using a spinner, and then dried at 70°C for 20 minutes.
A coating film with a thickness of 0.9 μm was obtained. This coating film was irradiated with ultraviolet light for 5 seconds under the same conditions as in Example 1, developed using a 0.2N aqueous solution of tetramethylammonium hydroxide, and then washed with water to obtain a sharp relief pattern on the edge surface. . In this example, the minimum
A fine repeating pattern with a width of 1 μm could be formed. Example 7 The composition shown in Example 1 was coated on a grained clean aluminum foil using a spin coater and dried. An original plate obtained under the same baking and developing conditions as in Example 1 was mounted on the plate cylinder of a lithographic printing machine and printed using printing ink and etching liquid, yielding good printed matter. Thus, it has been found that the composition described in this patent can also be used as a material for printing plate making. Comparative example: Evaluation of the resolution of a negative photoresist (OMR-83 manufactured by Tokyo Ohka Kogyo Co., Ltd., base resin: cyclized polyisoprene rubber, photosensitizer: aromatic bisazide compound) that is sensitive to long wavelengths and developed with an organic solvent. The results are shown below as a comparative example. The above photoresist solution was spin-coated onto a silicon wafer using a spinner, and then dried at 90° C. for 30 minutes to obtain a coating film with a thickness of 0.8 μm. This coating film was closely covered with the same photomask as used in Examples 1 to 6, and irradiated with ultraviolet rays for 3 seconds from a distance of 30 cm using a 500 W high-pressure mercury lamp. Add this to xylene 3
Developed with a mixture of 7 volumes of n-heptane and washed with n-butyl acetate to create a relief.
I got the pattern. In this experiment, the resolution width of the fine repeating pattern formed was limited to a minimum width of 2 μm,
Patterns with widths smaller than this cause a so-called traversal phenomenon in which the lines are deformed into a zigzag shape, making it impossible to faithfully transfer the photomask pattern. As described above in detail, the present invention has made it possible to provide a photosensitive resin composition with high sensitivity, high mass productivity, and excellent resolution. The photosensitive resin composition of the present invention is particularly excellent in terms of pattern resolution, and is useful for pattern formation of highly integrated semiconductors.

Claims (1)

[Scope of Claims] 1 (a) at least one compound selected from homocondensed novolac resins, cocondensed novolac resins, polyhydroxystyrene homopolymers, and polyhydroxystyrene copolymers; (b) the following: General formula [] (However, Y is [Formula] [Formula] [Formula] R ¹ is lower alkylene, aminoalkylene, Z is -NR ² ₂ , -OR ² (However, R ² represents hydrogen or a lower alkyl group) , N ₃ − is −Y
-R ¹ Located in the para or meta position relative to Z. ) A photosensitive resin composition comprising a compound represented by: