JPS63128335A - Photosensitive composition and pattern forming method - Google Patents

Abstract

PURPOSE:To obtain good light shielding property at a shadow part and stability of the pattern by composing the titled composition of a specific diazonium salt, a Bronsted acid, a nonionic surfactant, a resin binding agent and a solvent. CONSTITUTION:The titled composition is composed of the diazonium salt shown by formula I or II, the Bronsted acid, the nonionic surfactant, the resin binding agent and the solvent. In formulas I and II, R1 an R2 are each hydrogen atom, 1-6 C alkyl, phenyl group of R1 and R2 together with a binded nitrogen atom may form 3-7 membered rings through carbon, oxygen or nitrogen atom, R3 and R4 are each hydrogen, halogen atom, 1-6 C alkyl, 1-6 C alkoxy or 2-6 C alkenyl group, X is an anion capable of forming the diazonium salt. Thus, the sticking property of a photosensitive film formed on a resist pattern is improved, and the foaming of the photosensitive films due to a nitrogen gas generated from both the resist film and the photosensitive film at the time of exposure is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to a photosensitive composition and a pattern forming method using the same, and more specifically, to photolithography in the production of high-density semiconductor devices, etc. The present invention relates to a photosensitive composition useful in processes and a pattern forming method using the same.

(Prior Art) As semiconductor integrated circuits such as LSI and VLSI become highly integrated, the dimensions of elements, wiring, etc. tend to become smaller.

For this reason, it is required that the dimensional accuracy of elements, wiring, etc. be extremely strictly controlled. The production of these semiconductor integrated circuits requires ultraviolet exposure technology (wavelengths of 2 and 3
00 to 45 Or+m) is commonly used. However, such technology cannot cope with the increasing density of integrated circuits.
This includes the challenges of improving the resolution of exposure equipment and forming fine patterns. In order to overcome this problem, various research and development efforts have been made in terms of resist materials, and the following proposals have been made, for example.

JP-A-52'-130286 describes a method in which a photodegradable photosensitive substance is added to a negative photoresist to absorb scattered light and the like for the purpose of improving resolution. However, this method is not sufficiently effective because the amount of photosensitive material added affects the resist function.

Furthermore, for the purpose of improving resolution, a method has been proposed in which a photosensitive film containing a photobleachable substance is provided on a resist film. This method changes the illuminance distribution of the pattern by passing it through a photobleachable film, and the optical contrast with respect to the resist is apparently improved. That is, the amount of color fading is small in shadow areas where the amount of light is relatively small, and conversely, the amount of color fading is large in highlight areas. Therefore, the amount of transmitted light in the highlight portion is relatively stronger than that in the shadow portion, and the upper optical contrast with respect to the resist film is apparently improved. In order to effectively carry out this optical contrast improvement method, the color fading substance must satisfy the following conditions. (2) Fading while sufficiently absorbing the light that sensitizes the resist, (2) Fading speed is close to the photosensitive speed of the resist, and (2) Transforming into a sufficiently transparent material after fading.

As a method for improving the above-mentioned optical contrast, specifically, Japanese Patent Laid-Open No. 54-64971 and Japanese Patent Laid-Open No. 54-7
A method of providing a photobleachable positive resist film on a negative resist film is known, as described in Japanese Patent No. 0761.

However, in this method, since the absorption coefficient of the positive resist is small, it is not possible to sufficiently block the light rays in the shadow portion.

In order to improve this problem, increasing the thickness of the positive resist will improve the light-shielding ability, but the image will become blurred and the resolution will deteriorate. Further, JP-A-59-104642 describes the use of arylnitrone as a color-fading substance. In this case, since the absorption coefficient is large, the photosensitive film can be made thinner, and resolution can be improved.

However, since arylnitrones are unstable,
It is easily decomposed by water or heat, making it difficult to control during the manufacturing process. As a result, there was a problem that fine patterns could not be stably formed.

Moreover, since arylnitrone decomposes in aqueous solution,
An organic solvent had to be used as the solvent for the photosensitive solution, and as a result, after exposure, it was necessary to peel off the photosensitive film with an organic solvent and then develop the resist, complicating the manufacturing process. .

(Problems to be solved by the invention) The present invention solves the above conventional problems = 9
- A photosensitive composition that can form a photosensitive film that has good light-shielding properties and stability in shadow areas, and that uses the photosensitive composition to form fine patterns with high precision and stability. The purpose of this invention is to provide a method that can be easily formed.

(Means for Solving the Problems) The invention of Section 1 of the present application provides a diazonium salt represented by the following general formula (I) or (II), a Brønsted acid, a nonionic surfactant, a resin binder, and a solvent. A photosensitive composition comprising:

However, R1 and R2 in the formula may be the same or different, and each represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms,
a phenyl group or a carbon atom together with a bonded nitrogen atom,
Number of members formed through oxygen atoms or nitrogen atoms: 3~
7 ring, and R3 and R4 may be the same or different, and each represents a hydrogen atom, a halogen atom, and a carbon number of 1 to 6.
represents an alkyl group, an alkoxy group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, or an anion capable of forming a diazonium salt.

The diazonium salts represented by the above general formulas (I) and (II) have an absorption band in the vicinity of 350 to 500 nm, so the g-line of the light (mercury lamp) commonly used for pattern exposure of integrated circuits. (wavelength 436nm), h-line (
It has high absorption efficiency for the 1-line (wavelength: 405 nm) and the 1-line (wavelength: 365 nm), and can very effectively block light in shadow areas, so it is essential for forming good patterns.

In such a diazonium salt, examples of the alkyl group having 1 to 6 carbon atoms include methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, isopentyl group, neopentyl group, hexyl group, Examples include isohexyl group and t-hensyl group. In the same diazonium salt, the 3-7 membered ring formed through a carbon atom, an oxygen atom, or a nitrogen atom together with a bonded nitrogen atom includes a pyrrolidino group, a piperidino group, a morpholino group, an ethyleneimino group, and a polymethylene group. Examples include an imino group and a cyclohebutylamino group. Examples of the alkoxy group having 1 to 6 carbon atoms include methoxy group, ethoxy group, propoxy group, isopropoxy group,
Examples include butoxy group, isobutoxy group, S-butoxy group, t-butoxy group, pentyloxy group, isopentyloxy group, S-pentyloxy group, t-pentyloxy group, and hexyloxy group. Examples of the alkenyl group having 2 to 6 carbon atoms include vinyl group, allyl group, isopropenyl group,
Examples include 1-propenyl group, 1-butenyl group, and 2-methylallyl group. Examples of anions capable of forming a diazonium salt represented by Examples include organic acid anions such as acids and sulfate ions. Specific examples of such diazonium salts include:
4-N,N-dimethylaminobenzenediazonium salt,
4-N.

N-diethylamino-2-ethoxybenzenediazonium salt, 4-N-phenylamino-2-methoxybenzenediazonium salt, 4-morpholinobenzenediazonium salt, 4-morpholino-2,5-dibutoxybenzenediazonium salt, 4-pyrrolidino- Examples include 3-methoxybenzenediazonium salt, 4-N,N-dimethylaminonaphthalenediazonium salt, and 4-N-phenylaminonaphthalenediazonium salt.

The above-mentioned Brønsted acid promotes the solubility of the diazonium salt represented by the above general formula, provides a photosensitive film with excellent light-shielding properties, and also converts the photosensitive composition into an acidic solution, suppressing decomposition of the diazonium salt. It has the effect of increasing storage stability. Such Brønsted acids include hydrochloric acid, sulfuric acid, nitric acid and other mH1-free or acetic acid, benzenesulfonic acid,
p-toluenesulfonic acid, ethylbenzenesulfonic acid,
Organic acids such as dodecylbenzenesulfonic acid, salicylic acid, sulfosalicylic acid, naphthalenesulfonic acid, phenol, methylphenol, dimethylphenol, p-tert-butylphenol, phenol-4-sulfonic acid can be used. These Brønsted acids may be used alone or in a mixture of two or more.

The above-mentioned nonionic surfactant has the effect of forming a photoresist film with good adhesion on the resist film and preventing foaming of the photoresist film caused by nitrogen gas generated from both the resist film and the photoresist film during exposure. .

That is, the photosensitive agent of the resist film (for example, naphthoquinone diazide in a positive resist and an azide compound in a negative resist) is decomposed by exposure and releases nitrogen gas. Furthermore, even in the photoresist film of the present invention, the diazonium salt decomposes upon exposure to release nitrogen gas. These nitrogen gases are rapidly generated at the start of exposure, so if the resist film has poor adhesion to the photoresist film, they remain in the form of bubbles at the interface between the two films, making it difficult to form fine patterns with high precision. It becomes difficult to form. Further, the nonionic surfactant has the function of accelerating the permeation of the developer during development, facilitating the removal of the photoresist film, and preventing the photoresist film from remaining on the resist film.

Furthermore, during coating, it has the effect of forming a homogeneous and smooth photoresist film on the resist film.

In addition to nonionic surfactants, there are anionic surfactants, cationic surfactants, and amphoteric surfactants, but for the following reasons, photosensitive compositions such as nonionic surfactants It is not suitable for use as a compounding ingredient in products. That is, anionic surfactants tend to decompose in acidic solutions and react with diazonium salts to form insoluble precipitates. Furthermore, cationic surfactants and amphoteric surfactants have a low effect of improving adhesion and permeability.

As mentioned above, nonionic surfactants are essential for forming fine patterns with high precision.For example, nonionic surfactants such as fluorine, silicon, polyolefin, fatty alcohol, and fatty acid Agents can be mentioned. The proportion of the nonionic surfactant to be blended is desirably in the range of 0.01 to 10% by weight, more preferably in the range of 0.5 to 5% by weight, based on the solid content of the photosensitive composition. Note that the nonionic surfactants can be used as a mixture of two types, but in this case, the total amount of each nonionic surfactant may be blended within the above range.

The reason why the amount of nonionic surfactant is limited to the above range is that if the amount is less than 0.01% by weight, the adhesion between the resist film and the photoresist film formed will not be sufficient, so Sometimes foaming of the photoresist film occurs, while the amount is 10
This is because if the amount exceeds % by weight, the compatibility with the resin binder decreases, and there is a possibility that a homogeneous photosensitive film may not be obtained.

Examples of the resin binder include polyvinyl alcohol, polyvinylpyrrolidone, a copolymer of vinylpyrrolidone and vinyl alcohol, a copolymer of vinyl methyl ether and maleic anhydride, methylcellulose, hydroxymethylcellulose, hydroxypropylcellulose, cellulose acetate butylene, etc. Polymer compounds such as cellulose acid, cellulose acetate, polyvinyl butyral, and copolymers or derivatives thereof can be mentioned. These resin binders may be used alone or in a mixture of two or more.

For example, water can be used as the solvent.

Next, the pattern forming method of the second invention of the present application will be explained in detail.

First, a resist film is formed on a substrate such as a semiconductor wafer or a blank mask. The resist used here is not particularly limited, but includes, for example, a positive resist consisting of a naphthoquinone diazide sulfonic acid ester and a cresol novolak resin, a rubber-based negative resist consisting of a bisazide compound blended with cyclized polyisoprene, a polyvinylphenol resin or azide. Mention may be made of negative resists dissolved in phenolic novolac resins.

Next, a photosensitive solution prepared from the photosensitive composition of the present invention described above is applied onto the resist film using, for example, a spinner, and dried to form a photosensitive film. The viscosity of this photosensitive liquid is adjusted to 5 to 800 cps, preferably 10 to 200 cps, considering application using a spinner or the like. The thickness of the photoresist film is related to the light-shielding ability of the photoresist film, so it cannot be absolutely limited, but if it is less than 500 people, pinholes may occur, while if it exceeds 5 μm, the image may become out of focus. Therefore, it is desirable that the thickness be in the range of 500 to 5 μm, more preferably 1000 to 2 μm.

Next, the photoresist film and the resist film are pattern-exposed to ultraviolet light using a mask on which a predetermined pattern is formed. Thereafter, the photoresist film is removed and the resist film is developed simultaneously using a developer to form a predetermined resist pattern. In this case, depending on the type of developer, after exposure, the photoresist film may be first removed with water and then the resist film may be developed with a predetermined developer to form a resist pattern.

(Function) The photosensitive composition of the present invention has an absorption band of 350 to 500.
Because it contains a diazonium salt expressed by the general formula, which is around nm
It is possible to form a photoresist film that has high absorption efficiency for m), h-line (wavelength: 405 nm), and i-line (wavelength: 385 nm), and can block light in shadow areas extremely effectively. In addition, since a nonionic surfactant is blended into the photosensitive composition of the present invention, the adhesion of the photosensitive film formed on the resist film is improved, and both the resist film and the photosensitive film are removed during exposure. It is possible to prevent bubbling of the photoresist film caused by the generated nitrogen gas, and also to speed up the permeation of the developer during development, making it easier to remove the photoresist film.

After forming the above-mentioned photoresist film on the resist film,
When exposed to ultraviolet light using a mask, the exposed areas of the photoresist film efficiently absorb the light and fade, resulting in a sufficiently transparent pattern, and the light rays in the shadow areas can be sufficiently blocked, allowing The resist film can be subjected to pattern exposure faithful to the pattern of the mask. Therefore, a fine resist pattern faithful to the pattern of the mask can be formed with high precision through the subsequent development process.

(Example of the invention) The present invention will be explained in detail below.

Example 1 1,2-naphthoquinone diazide was deposited on a silicon wafer.
A positive resist (product name: 0FPR-800, manufactured by Tokyo Ohka Kogyo Co., Ltd.) in which a 5-sulfonic acid ester compound was dissolved in a solvent together with an m-cresol novolac resin was spin-coated and dried to form a resist film with a thickness of 1.5 μm. was formed.

Next, a photosensitive solution having the following composition I was prepared, and this photosensitive solution was spin-coated on the positive resist film 2, and then 90%
It was dried at .degree. C. for 60 seconds to form a 0.4 .mu.m photosensitive film.

= 20- [Composition I of photosensitive liquid] 4-morpholino-2,5-dibutoxybenzenediazonium-p-toluenesulfonate 40+n mol p-toluenesulfonic acid 401TIUlo
1 Vinyl methyl ether-maleic anhydride copolymer (G
AP product name: GANTREZ AN-189)
109 Polyoxyethylene nonyl phenyl ether surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Neugen EA-
120) 1 g pure water 200 ships However, a sample of this Example 1 in which a positive resist film and a photoresist film were formed on a silicon wafer, and a sample in which only a positive resist film similar to Example 1 was formed on a silicon wafer Sample (Comparative Example 1)
) was exposed using a 5-body 1-reduction projection exposure device with a numerical aperture of 0.35 and a wavelength of 43 Bnm, and developed to form a resist pattern, and these resist patterns were observed using micrographs to examine resolution. As a result, the minimum line width of a resist pattern that maintains a good cross-sectional shape is -21
= It was confirmed that an extremely fine resist pattern of 0.7 μm could be formed in Example 1, whereas it was 1.2 μm in Comparative Example 1.

Example 2 A sample similar to Example 1 was prepared except that a photosensitive solution having the following composition (1) was used.

[Composition of photosensitive liquid■]

4-pyrrolidino-3-methoxybenzenediazonium-
Boron tetrafluoride salt 40 m mol Ethylbenzenesulfonic acid 40 m mol Polyvinylpyrrolidone (trade name manufactured by GAP Co., Ltd. - Fluorine surfactant (trade name manufactured by Daiichi Ink Chemical Co., Ltd.: F-171)
1g pure water
200 mi However, the sample of this Example 2 and a sample in which a positive resist film similar to that of Example 1 and a photoresist film made of a photosensitive solution excluding the surfactant in the above composition (2) were formed on a silicon wafer (comparison). Regarding Example 2), resist patterns were formed by exposure and development in the same manner as in Example 1, and these resist patterns were observed using micrographs to examine resolution. As a result, it was confirmed that the minimum line width of a resist pattern that maintained a good cross-sectional shape was 0.7 μm in both Example 2 and Comparative Example 2, and that extremely fine resist patterns could be formed. However, the pattern width variation (σ
), it was found that in Example 2, σ is 0.0113
In Comparative Example 2, σ was 0.082, and it was confirmed that the resist pattern of Example 2 had significantly improved dimensional stability.

Example 3 A sample similar to Example 1 was prepared except that a photosensitive solution having the following composition (1) was used.

[Composition of photosensitive liquid■]

4-N,N-dimethylaminobenzenediazonium-sulfosalicylate 40 m molp-h luenesulfonic acid 20 m mol polyvinylpyrrolidone (product name: Ni-90, manufactured by GAP)
10g nonionic surfactant (product name L-62 manufactured by Kyodenka Kogyo Co., Ltd.)
0.59 pure water
200M The sample of Example 3 was exposed and developed in the same manner as in Example 1 to form a resist pattern, and these resist patterns were observed using micrographs to examine resolution. As a result, it was confirmed that the minimum line width of a resist pattern that maintains a good cross-sectional shape can be significantly reduced to 0.5 μm.

Example 4 A sample similar to Example 1 was prepared except that a photosensitive solution having the following composition (1) was used.

[Composition of photosensitive liquid■]

4-N,N-dimethylaminonaphthalenediazonium-
p-Toluenesulfonate 40m mo! hydrochloric acid
20 m mol vinyl methyl ether-maleic anhydride copolymer (product name: GANTREZ AN-IEi9, manufactured by GAP) 0 g polyoxyethylene nonylphenyl ether surfactant (product name: Ninogen EA-120, manufactured by Dai-Kogyo Seiyaku Co., Ltd.)
0.8 g pure water
200 g of the sample of this Example 4 and a sample in which a positive resist film similar to that of Example 1 and a photoresist film made of a photosensitive liquid except for the surfactant in the above composition (2) were formed on a silicon wafer (comparative example). Regarding 4), resist patterns were formed by exposure and development in the same manner as in Example 1, and these resist patterns were observed using micrographs to examine resolution. As a result, in Example 4, 0.
Although a fine resist pattern of 6 μm could be formed, in Comparative Example 4, foaming was severe during exposure, making it difficult to form the pattern.

[Effects of the Invention] As detailed above, according to the present invention, the g-line (
Wavelength 43Bnm), H-line (wavelength 405nm)
, has high absorption efficiency of i-rays (wavelength 365 nm), can block shadow areas extremely effectively, has good adhesion to the resist film, prevents bubbling caused by nitrogen gas generated during exposure, and has a high absorption efficiency during development. A photosensitive composition capable of forming a photosensitive film that can be easily removed by a developer can be provided. In addition, by forming a photosensitive film made of such a photosensitive composition on a resist film and then exposing it to ultraviolet light using a mask, the exposed areas of the photosensitive film efficiently absorb the light and fade, making it fully transparent. At the same time, the light rays in the shadow area can be sufficiently blocked, so that the resist film under the photoresist film can be exposed in a pattern that is faithful to the pattern of the mask. A pattern forming method that can form fine resist patterns with high accuracy can be provided.

Claims (14)

[Claims] (1) A photosensitive composition comprising a diazonium salt represented by the following general formula (I) or (II), a Brønsted acid, a nonionic surfactant, a resin binder, and a solvent. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) However, R_1 and R_2 in the formula may be the same or different, and are hydrogen atoms, Indicates a ring with 3 to 7 members formed through a carbon atom, an oxygen atom, or a nitrogen atom together with an alkyl group having 1 to 6 carbon atoms, a phenyl group, or a bonded nitrogen atom, and R_3 and R_4 may be the same. They may be different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, and X forms a diazonium salt. indicates an anion capable of. (2) The photosensitive composition according to claim 1, wherein the Brønsted acid is at least one compound selected from the group of inorganic acids and organic acids. (3) Bronsted acid is hydrochloric acid, sulfuric acid, nitric acid, acetic acid, benzenesulfonic acid, p-toluenesulfonic acid, ethylbenzenesulfonic acid, dodecylbenzenesulfonic acid,
Salicylic acid, sulfosalicylic acid, naphthalenesulfonic acid, phenol, methylphenol, dimethylphenol, p-tert-butylphenol, phenol-4-
3. The photosensitive composition according to claim 1 or 2, which is at least one compound selected from the group of sulfonic acids. (4) The photosensitive composition according to claim 1, wherein the nonionic surfactant is blended in an amount of 0.01 to 10% by weight based on the solid content of the photosensitive composition. . (5) The photosensitive composition according to claim 1, wherein the resin binder comprises a water-soluble polymer compound. (6) The resin binder is polyvinyl alcohol, polyvinylpyrrolidone, a copolymer of vinylpyrrolidone and vinyl alcohol, a copolymer of vinyl methyl ether and maleic anhydride, methylcellulose, hydroxymethylcellulose, cellulose acetate butyrate, acetic acid 6. The photosensitive composition according to claim 5, which is at least one compound selected from the group consisting of cellulose, polyvinyl butyral, and copolymers or derivatives thereof. (7) The photosensitive composition according to claim 1, wherein the solvent is water. (8) A photosensitive composition consisting of a diazonium salt represented by the following general formula (I) or (II), a Brønsted acid, a nonionic surfactant, a resin binder, and a solvent is applied onto the resist film. 1. A pattern forming method comprising the steps of: coating a photoresist film with a photoresist; and exposing by selectively irradiating a light beam capable of sensitizing both the resist film and the photoresist film. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) However, R_1 and R_2 in the formula may be the same or different, and are hydrogen atoms, Indicates a ring with 3 to 7 members formed through a carbon atom, an oxygen atom, or a nitrogen atom together with an alkyl group having 1 to 6 carbon atoms, a phenyl group, or a bonded nitrogen atom, and R_3 and R_4 may be the same. They may be different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, or an alkenyl group having 2 to 6 carbon atoms, and X forms a diazonium salt. indicates an anion capable of. (9) The pattern forming method according to claim 8, wherein the Brønsted acid is at least one compound selected from the group of inorganic acids and organic acids. (10) Bronsted acids include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, benzenesulfonic acid, p-toluenesulfonic acid, ethylbenzenesulfonic acid, dodecylbenzenesulfonic acid, salicylic acid, sulfosalicylic acid, naphthalenesulfonic acid, phenol, methylphenol, dimethyl Phenol, p-tert-butylphenol, phenol-4
- Claim 8 or 9 is characterized in that it is at least one compound selected from the group of sulfonic acids.
The pattern forming method described in section. (11) The pattern forming method according to claim 8, wherein the nonionic surfactant is blended in an amount of 0.01 to 10% by weight based on the solid content of the photosensitive composition. (12) The pattern forming method according to claim 8, wherein the resin binder is made of a water-soluble polymer compound. (13) The resin binder is polyvinyl alcohol, polyvinylpyrrolidone, a copolymer of vinylpyrrolidone and vinyl alcohol, a copolymer of vinyl methyl ether and maleic anhydride, methylcellulose, hydroxymethylcellulose, cellulose acetate butyrate, acetic acid 13. The pattern forming method according to claim 12, wherein the pattern forming method is at least one compound selected from the group consisting of cellulose, polyvinyl butyral, and copolymers or derivatives thereof. (14) The pattern forming method according to claim 8, wherein the solvent is water.