JPH02872A - Photosensitive resin composition and pattern forming method by using said composition - Google Patents

Abstract

PURPOSE:To form patterns of about 0.5mum with good accuracy by using the paired anion of a diazonium salt as the functional group of the polymer in a photosensitive resin. CONSTITUTION:The paired cation of the diazonium salt is expressed by the formula I and/or the formula II and the paired anion is expressed by the formula III and/or the formula IV. In the formulas I, II, R1, R1', R1'', R2, R3, R3' denote a hydrogen atom, alkyl group, etc.; X denotes an oxygen atom, sulfur atom, etc.; in the formulas III, IV, R denotes a hydrogen atom, alkyl group, etc.; X' denotes a hydrogen atom, lithium, etc.; m, n denote 0-5 integer [where (m+n)<=5]; m', n' denote 0-7 integer [where (m'+n')<=7]. The resist patterns of about 0.5mum are formed with good stability and resolution in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming fine patterns in the semiconductor field. For more details, apply a photosensitive resin to the resist,
The present invention relates to a fine pattern forming method for improving dimensional accuracy and resolution using a light exposure method.

[Problems to be solved by conventional technology and inventions] As semiconductors become more highly integrated, pattern dimensions tend to become increasingly finer, and in recent years, precision processing with line widths of 1 μm or less has become necessary. Ta. Various methods have been proposed to meet these demands.

For example, in terms of equipment, two points are expected to improve resolution based on optical theory: 1) shortening the wavelength of the light source; 2) using a lens with a large numerical aperture; and there are actually test machines on the market. However, if the wavelength of the light source is shortened, the transmittance of the lens decreases, making it impossible to obtain a sufficient amount of light. Also, when using a lens with a large numerical aperture,
Problems have been pointed out, such as the depth of focus becomes shallow and the resist is susceptible to unevenness on the surface of the applied resist. On the other hand, on the resist side, resists with high contrast (hereinafter referred to as high γ
It is written as resist. ) development is being attempted. It is true that using a high arrester will improve resolution slightly. Also,
The production of high-gamma resists can be achieved by adjusting the molecular weight and dispersion of the polymer in the resist.-0 However, this method is limited by the materials used, and has not been able to significantly improve resolution. .

In addition, in terms of lithography, 1) a method of using a multilayer resist, 2) a method of coating a photosensitive resin on a resist film, etc. have been proposed.

Methods using multilayer resists can resolve patterns of 1 μm or less, but there are still problems as an industrial method because the process is complicated, takes too much time to manufacture semiconductors, and yields are low. .

In the method of coating a photosensitive resin on a resist film, the light immediately after passing through a mask has a high contrast, but when it passes through a space and a lens, the contrast of the light decreases. This method aims to increase the contrast and improve resolution by passing this low-contrast light through a photosensitive resin.

As a photobleaching material contained in this photosensitive resin, a nitrone compound (JP-A-59-104642) or a diazonium salt (JP-A-60-238829) has been proposed.

The method using a nitrone compound certainly improves resolution, but it requires an intermediate layer between the lower resist layer and the upper photosensitive resin layer, which complicates the process and has the problem that the yield does not improve much. .

The method using diazonium salt uses i-line (365 nm)
Regarding exposure, the effect of improving resolution is not yet fully satisfactory, and furthermore, problems remain in terms of storage stability of diazonium salts.

That is, 0.5 μm pattern resolution and long-term material preservation have not been achieved.

[Means to solve the problem]

An object of the present invention is to solve the above-mentioned problems and to relate to a method of forming fine patterns using i-line exposure with high precision using a simple process.

Among the methods of providing a photosensitive layer on top of the resist that can be bleached by light, the present inventors determined that a method that allows the development of the lower layer at the same time would simplify the process and could be expected to significantly improve the resolution. We investigated a method using diazonium salt as a bleaching agent.

The present inventors used a method reported as a functional evaluation method for positive photoresists (18M Company, USA: F, Il,
Drill, el al chuacle+1za
lion of positive phororesi
sl, IEEE transactionon e
lecl+on Devices, vol ED-
22 No. 7 Ju171975), it was found that the resolution could be significantly improved by increasing the A value.

Generally, the A value is 9-upper, nT (glossy) T(o): initial transmittance d
T(0) T(oo): Final transmittance d: Indicated by film thickness, in order to improve the A value, reduce the film thickness d,
The photosensitive layer (upper layer) after bleaching has a high transmittance (that is, T
It is desirable that the value of (oQ) be as close to 100% as possible) and that the initial transmittance T(o) be as small as possible. In order to reduce T (o), it is sufficient to increase the degree of diazonium salt, which is a photobleaching agent, in the photosensitive layer.
If the concentration is increased, crystals of the photobleach will precipitate after application, which will actually lower the resolution. Furthermore, the method of adding additives such as sulfonic acid derivatives or their salts to increase solubility, as disclosed in JP-A-60238829, reduces coating properties, so there is a limit to the amount added. It was not effective. Furthermore, diazonium salts, which are photobleaching agents, have a problem of poor thermal stability.

Therefore, commonly known diazonium salt stabilizers,
For example, when we investigated the stability by adding phosphoric acid, organic phosphoric acid, citric acid, tartaric acid, etc., we found some improvement, so we added a large amount of additives for further improvement. The coating properties deteriorated and a decrease in resolution was observed.

In order to solve these problems, the present invention has been developed by applying a resist as a lower layer on a substrate, and then applying a photosensitive resin containing a diazonium salt (a photobleaching agent) as an upper layer. Provides a photosensitive resin composition, in which the counter anion of the diazonium salt is a compound containing a sulfonic acid group, and a pattern forming method using the same, in a method of forming a pattern by exposing both the upper layer and the lower layer to light. It is.

Counter anions that can be used in the present invention are not particularly limited, and examples include eH304 and organic carboxylic acids. Further, any compound containing an organic acid group or sulfonic acid group with a low P Ka value may be used, but the following structures are preferable.

R: hydrogen atom, alkyl group, aryl group.

Aralkyl group, alkoxy group, phenyl group, halogen atom, hydroxyl group or carboxyl group
Or: hydrogen atom, alkyl group, aryl group.

Aralkyl group, alkoxy group, phenyl group, halogen atom, hydroxyl group or carboxyl group Although the molar ratio between the group and the sulfone group in the above compound, which is a counter anion, is not particularly specified, it is desirable that the sulfone group is at least 1.1 times the mole of the diazo group.

The polymer in the photosensitive resin that can be used in the present invention is
Any polymer may be used as long as it dissociates into ions when dissolved in water and exhibits a P Ka value of 2 or less, but polymers having sulfonic acid groups are preferred.

Examples include polyvinylsulfonic acid, chondroitin sulfate, and salts thereof, but polymers having the following structure are most preferred.

That is, the present inventors conducted intensive studies focusing on the polymers used in photosensitive resins, and found that by using polymers containing benzenesulfonic acid groups, the solubility in solvents increases and coating films are improved. It has been found that the stability of diazonium salt can be further improved by inhibiting the precipitation of crystals of diazonium salt. As a result, it became possible to form fine patterns with high precision, and the present invention was completed.

The polymer contained in the photosensitive resin in the present invention is represented by the following structural unit.

so, y (however, the ratio ~R7 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a halogen atom, a nitrile group, 1 is a hydrogen atom,
an alkyl group having 1 to 4 carbon atoms, a halogen atom, a hydroxyl group, a carboxyl group, and Y represents a hydrogen atom, an alkali metal, an alkaline earth metal, and an ammonium group, respectively. ) Furthermore, the polymer used in the present invention may be a copolymer of compounds represented by the above-mentioned structural units or a copolymer with a generally known compound.

Examples of copolymers include styrene, α-methylstyrene, vinylpyridine, and acenaphthylene.

Vinyl aniline, vinylnaphthalene, vinyl acetophenone, acrylic acid and its derivatives, methacrylic acid or its esters, acrylonitrile, maleic anhydride, maleic imide or its derivatives, allyl ester, vinyl ester, acrolein 1 acrylamide or its modified product, propenylanisole , vinyl ether,
Examples include copolymers with indene, isoprene, etc.

The copolymerization ratio of the structural unit having a benzenesulfone group and, for example, the above-mentioned compound not having a benzenesulfone group is not particularly specified, but the content of the structural unit having a benzenesulfone group in the polymer may be 50 mol% or more. preferable. The solvent in the photosensitive resin may be any solvent as long as it does not dissolve the underlying resist, but water is preferred.

Furthermore, if necessary to improve solubility, additives such as phosphoric acid benzene sulfuric acid or its salt, sulfosalicylic acid or its salt, nicotinic acid, caffeine, etc. may be added to the photosensitive resin liquid.

In addition, the present inventors have conducted intensive studies on IJ attached to the polymer in the photosensitive layer, and have found that by using the functional group of the polymer in the photosensitive resin as the counter anion of the diazonium salt, the physical properties of the coating film can be improved. It has also been found that a large amount of diazonium salt can be dissolved without impairing the properties of the diazonium salt, and at the same time, the stability of the diazonium salt can be improved. As a result, it became possible to form fine patterns with high precision, and the present invention was completed.

That is, in the present invention, a photosensitive resin made of a diazonium salt as a photobleaching agent, water and/or an organic solvent, and a polymer is coated (upper layer) on a resist film (lower layer), and then both the upper layer and the lower layer are exposed to light at the same time. The present invention provides a pattern forming method characterized in that the counter anion of the diazonium salt is a functional group of a polymer in a photosensitive resin.

In the present invention, the polymer in the photosensitive resin that can be used dissociates into ions when dissolved in water, and has a low p K
Any polymer may be used as long as it exhibits an a value, but preferably a polymer having a sulfone group is used. Examples include polyvinyl sulfonic acid, chondroitin sulfate, and salts thereof, but polymers represented by the following structural units are most preferred, where R7 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms,
Halogen atom, nitrile group, interlock is hydrogen atom, carbon number is 1
-4 represents an alkyl group, a halogen atom, a hydroxyl group, or a carboxyl group. ) The counter cation of this polymer may be a hydrogen ion, an alkali metal ion, an alkaline earth metal ion, an ammonium ion, etc. in addition to the counter cation of the diazonium salt in the photosensitive resin.

Further, the polymer used in the present invention may be a copolymer of compounds represented by the above-mentioned structural units or a copolymer with a generally known compound.

For example, styrene, α-methylstyrene, vinylpyridine, acenaphthylene, vinylaniline, vinylnaphthalene, vinylacetophenone.

Acrylic acid and its derivatives, methacrylic acid and its esters, acrylonitrile, maleic anhydride, maleic imide and its derivatives, allyl esters, vinyl esters, acrolein.

Examples include acrylamide and its modified products, and copolymers with propenyl anisole, vinyl ether, indene, isoprene, and the like.

The copolymerization ratio of the structural unit having a benzenesulfone group and, for example, the above-mentioned compound not having a benzenesulfone group is not particularly specified, but the copolymerization ratio of the structural unit having a benzenesulfone group in the polymer is 50 mol% or more. It is desirable that there be.

In the polymer in the photosensitive resin, the molar ratio of the functional group serving as the counter anion of the diazonium salt to the free functional group is not particularly defined, but it is preferable that the free functional group is 30% or more. If necessary, phosphoric acid, organic acids, citric acid, tartaric acid, etc., which are known as stabilizers for diazonium salts, may be added to the photosensitive resin.

The method for producing a diazonium salt using a functional group of a polymer as a counter anion is to mix a stoichiometric excess of the above polymer into an aqueous solution of the diazonium salt, and then remove the low-molecular salt using a method such as dialysis. There is a method for obtaining a photosensitive resin containing a diazonium salt whose counter anion is a functional group of a polymer.

・Here, regarding the diazonium salt, as a result of research by the present inventors, its counter cation has the general formula (R1, R+',
R+'', R1 are each a hydrogen atom, an alkyl group, or an acetyl group. R1, R3' are each a hydrogen atom, an alkyl group,
Acetyl group, hydroxyl group, alkoxy group, halogen or nitrile group. X is an oxygen atom, a sulfur atom, or N1
(R4 is a hydrogen atom, an alkyl group, or an acetyl group) The absorption peak of compounds such as It turned out to be over 40% larger.

As a result, by using the diazonium salt according to the present invention, the A value becomes 10 or more, making it suitable for pattern resolution of, for example, 0.5 μm, which is the minimum dimension of a 16 megabit RAM, in a process step.

The pattern forming method of the present invention will be described in detail below.

First, a resist commonly used with a spinner, preferably a positive type resist, is applied to the wafer. The positive resist used may be any resist as long as it can also dissolve the photosensitive resin in the developing solution of the resist.

After applying the resist, prebaking is performed, and then a photosensitive resin consisting of a reaction product of a diazonium salt according to the present invention obtained by the above method and a polymer, water and/or an organic solvent is applied using a spinner.

After applying a photosensitive resin, both the upper and lower layers are exposed to sensitive light, and at the same time the resist is developed with the used resist developer solution, the photosensitive resin layer is also peeled off, thereby forming a fine pattern. It is.

[For production]

According to the present invention, by dissolving a large amount of diazonium salt suitable for i-line light into a photosensitive resin composition, it is possible to increase the A value, which is a coefficient for improving resolution, and at the same time improve the stability of the diazonium salt. It can also be set to 0.5
It is possible to form resist patterns in the vicinity of μm with good stability and high resolution.

〔Example〕

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited thereto.

Production Example 1 After adding 2 equivalents of 1.5-natal disulfonic acid to an aqueous solution of 4-morpholinobenzenediazonium chloride synthesized according to a conventional method, a diazonium salt was precipitated by salting out. Thereafter, this was vacuum dried to obtain a powdery diazonium salt.

Example 1 To 7.2 g of the diazonium salt obtained in Production Example 1, 10 g of polystyrene sulfonate sodium (PS-5.Molecular mold 50,000 manufactured by Tosoh Corporation) and 9 g of water (Ig) were added to produce a photosensitive resin aqueous solution. did.

This photosensitive resin aqueous solution was spin-coated on a quartz substrate to form a uniform thin film of 25 μm, and the transmittance before and after exposure was measured to determine the A value at 365 nm, which was 11.5. Next, after leaving this photosensitive resin aqueous solution in a constant temperature bath at 35°C for 25 days, the A value was measured again and was 11.5, indicating that the film thickness did not change even after coating and the storage stability was good. Ta.

Comparative Example 1 4-morpholinobenzenediazonium l/2Zn (1!2 salt 3 gq as diazonium salt) Polyvinylpyrrolidone (9 molecular weight 245
10 g) and 90 g of water were mixed to obtain an aqueous photosensitive resin solution. Result 4 of evaluating A value using the same method as Example 1
It was 6. Note that if the diazonium salt was dissolved in a content higher than this, crystals would precipitate in the coating film, making it impossible to form a uniform film. 2 at 35°C as in Example 1.
As a result of examining the A value after storage for 0 days, it was 1.6 and could not be put to practical use.

Example 2 The pattern forming method of the present invention will be explained using FIGS. 1 to 4. Positive photoresist 0F on silicon wafer 1
After applying PR-800 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) 2 to a film thickness of 0.9 μm, prebaking was performed at 80°C for 10 minutes (
(Fig. 1), and further added 0% of the photosensitive resin liquid 4 produced in Example 1.
．． It was applied to a film thickness of 25 μm (Figure 2). Subsequently, after exposure with an IO pair 11-line reduction exposure machine (stepper) equipped with a lens with a numerical aperture of 0.42 (Figure 3), development was performed with NMD3 (manufactured by Tokyo Ohka Kogyo (Φ)) (Figure 4). As a result of observing the cross-sectional shape of the obtained resist pattern with an electron microscope, a line/space pattern 2a of 0.50 μm in rectangular shape and having steep edges was obtained.

Comparative Example 2 A resist pattern was obtained in exactly the same manner as in Example 2, except that the photosensitive resin was not applied. However, the exposure amount required for transfer was about 1/2 of that in Example 1. As a result of observation using an electron microscope, a pattern of 0.6 μm could not be resolved.

Comparative Example 3 Pattern transfer was performed in the same manner as in Example 2, except that the photosensitive resin liquid obtained in Comparative Example 1 was used instead of the photosensitive resin liquid in Example 2. A 0.5 μm pattern could not be resolved, and the shape of the resist pattern had a poor contrast of <65°, so it could not be put to practical use.

Manufacturing example 2 The following compound was synthesized according to a conventional method.

Next, diazonium salt was precipitated by salting out after adding 2 equivalents of 1.5-natutaledisulfonic acid, and a powdery compound was obtained by vacuum drying.

Add 9.5 g of this powdered compound to polystyrene sulfonate ammonium salt (after replacing PS-5 from sodium salt to ammonium salt using an ion exchange resin, dehydrate and dry) 1
0 g and 90 g of water were added to obtain a photosensitive resin liquid.

Example 3 Using the photosensitive resin liquid of Production Example 2, spin coating was performed on a quartz substrate to create a uniform thin film of 0.29 μm,
The A value at 365 nm was found to be 12.2. Next, this photosensitive resin liquid was left in a constant temperature bath at 35° C. for 20 days, and then the A value was measured again and found to be 12.2, indicating that the coating properties did not deteriorate and the storage stability was good.

Comparative example 4 1.8 g of diazonium salt (compound below).

A photosensitive resin liquid was prepared by mixing 10 g of polyvinylpyrrolidone (manufactured by Hanka Kagaku Yakuhin, molecular weight: 24,500) as a polymer and 90 g of water. When the A value was measured, it was 4.8.

Note that when the diazonium salt was added and dissolved in this photosensitive resin liquid, crystals precipitated during coating, making it impossible to form a uniform film.

For a storage stability test, the photosensitive resin liquid was left in a constant temperature bath at 35°C for 20 days, and then the A value was measured again.
2, and could not be put to practical use.

Example 4 Positive photoresist 0FPR on silicon wafer
Spin coat 800 (Tokyo Ohka Kogyo (medium size)) to a film thickness of 0.9 μm.

After that, prebaking was performed at 80° C. for 110 minutes, and then the photosensitive resin liquid produced in Production Example 2 was applied to a film thickness of 0.22 μm.

Next, exposure was carried out using an 10 line stepper equipped with a lens having a numerical aperture of 0.42, and then development was carried out using NMD-3 (manufactured by Tokyo Ohka Kogyo ■).

As a result of observing the cross-sectional shape of the resist pattern with an electron microscope, a clear rectangular line/space pattern of 0.5 μm was obtained.

Comparative Example 5 The same experiment as in Example 4 was conducted except that the photosensitive resin liquid manufactured in Comparative Example 4 was used instead of the photosensitive resin liquid manufactured in Manufacturing Example 2. However, the exposure amount was 30% lower than in the example.

As a result of electron microscopic observation, the resolution was 08 μm.

Production Example 3 In order to conduct a stability test of diazonium salt, 100 ml of photosensitive resin having the following composition was produced.

Composition of photosensitive resin Polystyrene sulfonic acid sodium trilam salt (manufactured by Tosoh: PS-5) 10 g 4-morpholinobenzenediazonium chlorite Local zinc chloride double salt 4.8 g Water
90g Example 5 The photosensitive resin aqueous solution of Production Example 3 was applied on a quartz plate by spin coating to create a uniform thin film with a thickness of 0.35 μm,
The transmittance T(o) and T(OO) before and after exposure were measured, and the A value at a wavelength of 365 nm was evaluated to be 12.0. Further, the A value of the aqueous photosensitive resin solution of Production Example 3 was evaluated after being left in a thermostat at 35° C. for 20 days in the dark, and the result was 1!9, indicating good storage stability.

Comparative Example 6 4-morpholinobenzenediazonium chloride as a diazonium salt 3g of zinc chloride double salt 1 polyvinylpyrrolidone as a polymer (9 molecules m2.4 manufactured by Half Chemical Co., Ltd.)
50,000) I [1 g and 90 g of water were mixed to obtain a photosensitive resin aqueous solution. The A value was evaluated in the same manner as in Example 5 and was 4.6. Note that if the diazonium salt was dissolved in a content higher than this, crystals would precipitate in the coating film, making it impossible to form a uniform film. Similar to Example 1,
After being left in the dark at 35° C. for 20 days, the A value was 1.6, which made it impossible to put it to practical use.

Example 6 The pattern forming method of the present invention will be explained.

Positive photoresist 0FPR on silicon wafer
800 (manufactured by Tokyo Ohka Kogyo) to a film thickness of 0.9 μm. Thereafter, prebaking is performed at 80° C. for 10 minutes. Next, a photosensitive resin having the composition shown below is applied to a film thickness of 0.35 μm.

Composition of photosensitive resin 4-morpholino-2-ethoxybenzenediazonium chloride Zinc chloride double salt 4.8g Polystyrene sulfonate sodium salt 10g Water
90 g Next, exposure was performed using a 10:11 line reduction projection exposure machine (stepper) equipped with a lens with a numerical aperture of 0.42, and after transferring the mask pattern, 1
Developing was carried out for a minute.

As a result of observing the cross-sectional shape of the resist pattern with an electron microscope, a clear rectangular line of 0.5 μm was obtained.

Comparative Example 7 Except for applying the photosensitive resin, everything else was done (Example 6)
conducted the same experiment. However, the amount of exposure required for transfer is
It was half of the example. As a result of observation using an electron microscope, the resolution was 1.2 μm.

Example 7 The same experiment as in Example 6 was conducted except that polystyrene sulfonic acid was used instead of polystyrene sulfonate sodium salt, which is a polymer in the photosensitive resin used in Example 6. As a result, the resolution was 0.5 μm.

Comparative Example 8 In order to carry out a similar experiment using polyvinylpyrrolidone instead of polystyrene sulfonate sodium salt, which is the polymer in the photosensitive resin used in Example 6, a photosensitive resin was applied onto the resist film. Crystals of diazonium salt were observed. When the pattern was observed using an electron microscope after exposure and development, a clear pattern could not be obtained and the resolution could not be measured.

Example 8 Instead of the diazonium salt used in Example 6, 4-(N,
An experiment similar to Example 6 was conducted using N-dimethylamino)-2-ethoxybenzenediazonium chloride double salt of zinc chloride. The resolution was 0.5 μm.

Production Example 4 After adding twice the equivalent of sodium polystyrene sulfonate (PS-51 manufactured by Tosoh, molecular weight 50,000) to the synthesized aqueous solution of 4-morpholinobenzenediazonium chloride according to a conventional method, a commercially available cellulose dialysis membrane (Spectrum) was added. A polystyrene sulfonate salt having a sulfone group serving as a counteranion of the diazonium compound and a free sulfone group in a 1:1 molar ratio is obtained by removing low-molecular salts such as sodium chloride using a diazonium compound manufactured by Spectra/Poac). A photosensitive resin aqueous solution (weight concentration 15) was obtained.

Example 9 The photosensitive resin aqueous solution of Production Example 4 was applied onto a quartz plate using a spinner to create a uniform thin film with a thickness of 0.35 μm, and the values of transmittance T (o) and T (Oo) before and after exposure were determined. was measured and the A value at a wavelength of 365 nm was evaluated, and the result was 10.5. Further, the A value of the aqueous photosensitive resin solution of Production Example 4 was evaluated after being left in a thermostat at 35°C for 20 days in the dark, and the result was 10.5, indicating good storage stability.

Comparative Example 9 3 g of 4-morpholinobenzenediazonium chloride zinc chloride double salt as diazonium salt.

A photosensitive resin aqueous solution was obtained by mixing 10 g of polyvinylpyrrolidone (1 molecule FF 124,500, manufactured by Hanka Kagaku Yakuhin Co., Ltd.) as a polymer and 90 g of water. The A value was evaluated in the same manner as in Example 9 and was 6.5. Note that if the diazonium salt was dissolved in a content higher than this, crystals would precipitate in the coating film, making it impossible to form a uniform film. As in Example 9, the A value after being left in the dark at 35° C. for 20 days was 1.6, and could not be put to practical use.

Example 10 The pattern forming method of the present invention will be explained.

Positive photoresist 0FPR on silicon wafer
800 (manufactured by Tokyo Ohka Kogyo) to a film thickness of 0.9 μm, and then prebaked at 80° C. for 10 minutes. Next, the photosensitive resin obtained in Production Example 4 was added to 0.
The coating was applied to a film thickness of 35 μm. Next, exposure was performed using a 10:11 line reduction projection exposure machine (stepper) equipped with a lens with a numerical aperture of 0.42, and after the mask pattern was transferred, a developer N~10-3 (manufactured by Tokyo Ohka Kogyo) was used. Developed for 1 minute. As a result of observing the cross-sectional shape of the obtained resist pattern with an electron microscope, a line/space pattern of 0.5 μn1 in size was obtained, which was rectangular and had steep edges.

Comparative Example 10 A resist pattern was obtained in exactly the same manner as in Example 10, except that the photosensitive resin was not applied. However, the exposure amount required for transfer was the same as that of Example 1o. As a result of observation with an electron microscope, a pattern of 0.5 μm could not be resolved.

Comparative Example 11 Pattern transfer was performed using a conventional technique. That is, pattern transfer was performed in exactly the same manner as in Example In, except that the photosensitive resin obtained in Comparative Example 9 was used instead of the photosensitive resin in Example 10. As a result of observation with an electron microscope, 0.5 μm
The pattern could not be resolved and the shape of the resist pattern was poor, making it impossible to put it to practical use. That is, the pattern had film burrs, and its contrast had deteriorated to 65°.

Example 11 Diazonium salt with 4-(N,N-dimethylamino)-2
- Photosensitive resin aqueous solution (weight concentration 1
3.5%). The wavelength is 365n using the same method as in Example 9.
The result of evaluating the A value at m was 12.0.

In addition, 100% of 0FPR-800 was placed on the silicon wafer.
After applying the photosensitive resin to a thickness of 0.30 μm and prebaking at 80° C. for 10 minutes, the photosensitive resin was applied to a thickness of 0.30 μm. Next, exposure was performed using a 10:1 stepper equipped with a lens with a numerical aperture of 0.42, and 1:1 with N~ID-3.
Developed for minutes. When the cross-sectional shape of the obtained resist pattern was observed with an electron microscope, it was found that a 0.5 μm line/space pattern with steep edges was resolved.

Comparative Example 12 A resist pattern was obtained in exactly the same manner as in Example 11, except that the photosensitive resin was not applied. However, the exposure amount required for transfer was about 273 in Example 10. As a result of observation using an electron microscope, the resolution was 0.8 μm.

Example 12 Diazonium salt with 4-(N,N-dimethylamino)-2
A photosensitive resin aqueous solution (a degree: 14%) was obtained in the same manner as in Production Example 4 using -methoxybenzenediazonium chloride and polystyrene sulfonic acid as the polymer. Using this, pattern transfer was performed in the same manner as in Example 11, and as a result, a 0.5 μm line/space pattern was resolved as in Example 11.

〔Effect of the invention〕

The composition of the present invention is stable and has a large contrast-improving effect, and according to the present invention, it is stable in terms of materials, and it is possible to make low-contrast light into high contrast again without going through a complicated process. This makes it possible to form patterns with a diameter of about 15 μm with high accuracy. The present invention provides an optical lithography technology that meets the demand for miniaturization of circuit pattern dimensions in semiconductor manufacturing.

Furthermore, since the depth of focus increases, the yield of semiconductors can be improved, which has great industrial value.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views of process steps of the method of the present invention. ■...Substrate 2...Resist 3...I-line (365nm) light 4...
...Photosensitive resin 2a according to the present invention...Pattern

Claims (12)

[Claims] (1) In a photosensitive resin composition consisting of a diazonium salt, which is a photobleaching agent, water and/or an organic solvent, and a polymer, the counter cation of the diazonium salt has the general formula ▲ mathematical formula, chemical formula, table, etc. ▼ and/or ▲ There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1, R_1', R_1'', and R_2 are each a hydrogen atom, an alkyl group, or an acetyl group. R_3, R_3
' is each a hydrogen atom, an alkyl group, an acetyl group, a hydroxyl group, an alkoxy group, a halogen or a nitrile group. X
is an oxygen atom, a sulfur atom, or NR_4 (R_4 is a hydrogen atom, an alkyl group, or an acetyl group), and the counter anion is a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and/or ▲ Numerical formulas, chemical formulas, tables, etc. ▼ (However, R: hydrogen atom, alkyl group, aryl group, aralkyl group, alkoxy group, phenyl group, halogen atom, hydroxyl group, or carboxyl group X': hydrogen atom, lithium, sodium, potassium, or ammonium group m, n : Each is an integer of 0 to 5 (however, m+n≦5) m', n': Each is an integer of 0 to 7 (however, m'+n'≦7) A photosensitive resin composition. (2) The photosensitive resin composition according to claim 1, wherein the polymer has an organic acid group having a PKa value of 2 or less. (3) The photosensitive resin composition according to claim 2, wherein the organic acid group having a PKa value of 2 or less has a structure containing a sulfonic acid group. (4) The photosensitive resin composition according to any one of claims 1 to 3, wherein the polymer has a repeating structure of the following structural units. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_5 to R_7 are hydrogen atoms, and the number of carbon atoms is 1 to 1, respectively.
4 alkyl group, halogen atom, nitrile group, R
_8 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a halogen atom, a hydroxyl group, or a carboxyl group, and Y is a hydrogen atom, an alkali metal, an alkaline earth metal, or an ammonium group. ) (5) The photosensitive resin composition according to any one of claims 1 to 3, wherein the polymer is a copolymer containing the following structural units. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_5 to R_7 are hydrogen atoms, alkyl groups with 1 to 4 carbon atoms, halogen atoms, nitrile groups, R_8 is hydrogen atoms and 1 to 4 carbon atoms. Alkyl group, halogen atom, hydroxyl group, carboxyl group, Y represents hydrogen atom, alkali metal, alkaline earth metal, ammonium group, respectively.) (6) In a photosensitive resin composition consisting of a diazonium salt, which is a photobleaching agent, water and/or an organic solvent, and a polymer, the counter cation of the diazonium salt has the general formula ▲ mathematical formula, chemical formula, table, etc. ▼ and/or ▲ There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1, R_1', R_1'', and R_2 are each hydrogen atom, alkyl group, or acetyl group. R_3, R_
3' is each a hydrogen atom, an alkyl group, an acetyl group, a hydroxyl group, an alkoxy group, a halogen or a nitrile group. A photosensitive resin composition characterized in that X is an oxygen atom, a sulfur atom, or NR_4 (R_4 is a hydrogen atom, an alkyl group, or an acetyl group), and the counter anion is a functional group of a polymer. (7) The photosensitive resin composition according to claim 6, wherein the functional group of the polymer is a sulfone group. (8) The photosensitive resin composition according to claim 6 or 7, wherein the polymer has a repeating structure of the following structural units. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_5 to R_7 are hydrogen atoms, alkyl groups with 1 to 4 carbon atoms, halogen atoms, nitrile groups, R_8 is hydrogen atoms and 1 to 4 carbon atoms. (Indicates alkyl groups, halogen atoms, hydroxyl groups, and carboxyl groups.) (9) The photosensitive resin composition according to claim 6 or 7, wherein the polymer is a copolymer containing the following structural units. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_5 to R_7 are hydrogen atoms, alkyl groups with 1 to 4 carbon atoms, halogen atoms, nitrile groups, R_8 is hydrogen atoms and 1 to 4 carbon atoms. (Indicates alkyl groups, halogen atoms, hydroxyl groups, and carboxyl groups.) (10) In a photosensitive resin composition consisting of a diazonium salt as a photobleaching agent, water and/or an organic solvent, and a polymer, the counter cation of the diazonium salt has the general formula ▲ mathematical formula, chemical formula, table, etc. ▼ and/or ▲ There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1, R_1', R_1'', and R_2 are each hydrogen atom, alkyl group, or acetyl group. R_3, R_
3' is each a hydrogen atom, an alkyl group, an acetyl group, a hydroxyl group, an alkoxy group, a halogen or a nitrile group. A photosensitive resin composition characterized in that X is an oxygen atom, a sulfur atom, or NR_4 (R_4 is a hydrogen atom, an alkyl group, or an acetyl group), and the polymer has a repeating structure of the following structural units. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_5 to R_7 are hydrogen atoms, and the number of carbon atoms is 1 to 1, respectively.
4 alkyl group, halogen atom, nitrile group, R
_8 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a halogen atom, a hydroxyl group, or a carboxyl group, and Y is a hydrogen atom, an alkali metal, an alkaline earth metal, or an ammonium group. ) (11) In a photosensitive resin composition consisting of a diazonium salt as a photobleach, water and/or an organic solvent, and a polymer, the counter cation of the diazonium salt has the general formula ▲ mathematical formula, chemical formula, table, etc. ▼ and/or ▲ There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_1, R_1', R_1'', and R_2 are each hydrogen atom, alkyl group, or acetyl group. R_3, R_
3' is each a hydrogen atom, an alkyl group, an acetyl group, a hydroxyl group, an alkoxy group, a halogen or a nitrile group. A photosensitive resin composition characterized in that X is an oxygen atom, a sulfur atom, or NR_4 (R_4 is a hydrogen atom, an alkyl group, or an acetyl group), and the polymer is a copolymer containing the following structural units. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (However, R_5 to R_7 are hydrogen atoms, and the number of carbon atoms is 1 to 1, respectively.
4 alkyl group, halogen atom, nitrile group, R
_8 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a halogen atom, a hydroxyl group, or a carboxyl group, and Y is a hydrogen atom, an alkali metal, an alkaline earth metal, or an ammonium group. ) (12) In a method of forming a pattern by coating a photosensitive resin composition (upper layer) on a resist film (lower layer) and then exposing both the upper layer and the lower layer to light, as the upper layer, any one of claims 1 to 11. A pattern forming method characterized by using the photosensitive resin composition according to item 1.