JPS62215939A - Pattern forming process - Google Patents

Abstract

PURPOSE:To obtain fine patterns with high dimensional accuracy and to permit stable molding by incorporating a specified aryl nitron, polystyrene, and at least one of phenolic org. acid and sulfonic acid type org. acid. into photosensitive film on resist film. CONSTITUTION:Aryl nitron expressed by the formula I, polystyrene, and at least one of org. acid expressed by the formula II and III are incorpoprated into the photosensitive film on the resist film. In the formulas, R, R' are monocyclic arom. compd., n is zero or 1; R<1> and R<2> are H, halogen, OH group, COOH group, sulfo group, 1-5C alkyl, amino, nitro; the content of the org. acid is pref. 1-10wt% basing on the weight of polystyrene as binder. The photosensitive film is formed and then exposed through a specified pattern. Then, the photosensitive film is exposed and the resist is developed. Thus, finely processed pattern is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pattern forming method, and more particularly to a pattern forming method that allows fine patterns to be formed stably with high dimensional accuracy by a simple method.

[Technical background of the invention and its problems]

With the increasing density of integrated circuits, there is an increasing tendency for element processing to become dimensionally finer, and at the same time strict control of dimensional accuracy is required.

Ultraviolet exposure technology (wavelength:
300 to 45,011 m) are commonly used.

Since this technology can quickly respond to the increasing density of integrated circuits, it has the problems of improving resolution and forming fine patterns. In order to overcome this problem, the following proposals have been made as a result of research and development in various fields from the perspective of resist materials.

For example, JP-A-52-130286 describes a method of adding a photodegradable photosensitive substance 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.

On the other hand, for the purpose of improving resolution, there is a method of providing a photosensitive film containing a photobleachable substance on a resist film. This method changes the illuminance distribution of a pattern by passing it through a photobleachable film, thereby apparently improving the optical contrast with respect to the resist. In other words, the amount of color fading is small in shadow areas where light is relatively small (on the contrary), and the amount of color fading is large in illumination areas. Therefore, compared to the C shadow part,
The transmitted light rays of the illite portion become relatively strong, and the 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. These are: (1) it sufficiently absorbs the light that sensitizes the resist and fades; (the phantom fading speed is close to the photosensitivity speed of the resist; and (2) it transforms into a sufficiently transparent material after fading.

One proposal using this method is to provide a photobleaching positive resist film on a negative resist film for the purpose of substantially improving optical contrast (Japanese Patent Laid-Open No. 54-6
4971, Japanese Unexamined Patent Publication No. 70761/1983). However, in this case, since the absorption coefficient of the positive resist is small, it is not only not possible to sufficiently block the light rays in the shadow area, but also the light blocking ability can be improved by increasing the thickness of the resist, but the image is blurred. On the contrary, resolution deteriorates. Further, in Japanese Patent Application Laid-open No. 59-104642, arylnitrone is described as a color-fading substance. In this case, +C has a large extinction coefficient, so the photosensitive film can be made thinner,
Although the resolution is improved, arylnitrones are unstable and easily decomposed by water or heat, making it difficult to control the manufacturing process. As a result, it has been very difficult to obtain stable fine patterns.

Moreover, this arylnitrone has a considerably higher sensitivity to light than other photosensitizers, so there was a problem in that the contrast could not be improved under optimal conditions due to poor matching between the fading photosensitive film and the resist. .

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to provide a pattern forming method that allows fine patterns to be formed stably and with good dimensional accuracy using a simple method.

[Summary of the invention]

As a result of extensive research into materials for photoresist films formed on resist films, the present inventors have discovered that photoresists containing arylnitrone, polystyrene, and at least one of a heptanoyl-based and hissulfonic acid-based organic acid. We have completed the present invention by discovering that the film has a sufficiently large light-shielding ability, is excellent in stability, and can improve contrast under optimal conditions.

That is, the pattern forming method of the present invention is a method for forming a pattern on a resist film by forming a compound of the general formula (1): A method in which a photoresist film containing an arylnitrone (n is O or 1) is formed, and then a pattern is formed using a light beam that sensitizes both the resist and the arylnitrone. The following formula (wherein R' and a! may be the same or different, and are a hydrogen atom, a halogen atom, and a hydroxyl group, respectively.

It contains at least one of an organic acid represented by a carboxyl group, a sulfo group, an alkyl group having 1 to 5 carbon atoms, an amino group, or a nitro group. The content of this organic acid is particularly preferably from 1 to 10% by weight based on polystyrene.

In the method of the present invention, a resist film is first formed on the semiconductor urchin. The resist to be used is not particularly limited, but for example, a so-called positive resist consisting of a naphthoquinone diazide sulfonic acid ester and a cresol novolak resin, a so-called rubber-based negative resist consisting of a bisazide compound blended with cyclized polyisoprene, a polyvinyl phenol resin or a polyvinyl phenol resin, etc. Examples include negative resists dissolved in phenol novolac resins, and various resist materials in which dichromate is blended with water-soluble resins (Kofuri, Nakamura, Electronic Materials, 18°10, 40).
(1979)).

Next, on this resist film, an arylnitrone, polystyrene, and at least one of the phenolic and sulfonic acid group organic acids shown in formulas (2) and (3) above are dissolved in a suitable solvent. A photosensitive liquid is applied using a spinner, for example, and dried to form a photosensitive film.

The arylnitrone used in the present invention can be any of the conventionally known arylnitrones, but in order to effectively block the exposure light, it is necessary to select the arylnitrone appropriately depending on the wavelength.

For example, since the reduction projection exposure equipment currently widely used for pattern exposure of integrated circuits uses f-line (4361m) and requires ℃, arylnitron having an absorption band around 400 to 5QQnm is suitable.Also, according to the present invention The reason for using polystyrene as the binder polymer used in
This is also due to the large light-shielding ability in the photoresist state.

The reaction of arylnitrones is generally highly sensitive and difficult to match with the photoresist of the resist. Therefore, if the reaction of the above equation 'C can be partially suppressed, contrast improvement can be achieved under optimal conditions. The present invention is based on the discovery that the retention of the reactive group by hydrogen bonding is the most effective for M as described below.

-CH=N-R: +-OH→-CH=N-R'↓ 00......HO- This also leads to increasing the stability of arylnitro/ to heat, and the phenol The above objective can be achieved by appropriately determining the content of the sulfonic or sulfonic organic acids. The content of the '/4 organic acid is sometimes preferably 1 to 10% by weight relative to the binder polymer polystyrene.

This is because if the amount is less than 1%, the substantial effect will be weak, and if it exceeds 10%, the photosensitive speed will suddenly decrease.

The method of the present invention involves forming a photoresist film made of the above-mentioned components, and then exposing the pattern by irradiating a light beam (for example, ultraviolet light with a wavelength of 400 nm or more) that acts on both the resist and the arylnitron through a predetermined pattern. . Thereafter, the photoresist film is removed and the resist is subsequently developed to form a desired fine pattern.

Known methods may be applied to these exposures, removal of the photosensitive layer, and development of the resist layer.

[Embodiments of the invention]

α-(4-dibutylaminophenyl)-N-(4-methoxycarbonyl, 3-methylphenyl)nitrone IF and polystyrene (Mitsubishi Monsanto HH105) 1f
and 0.02f of para-tertiary butylphenol were dissolved in xylene to prepare a photosensitive solution, which was coated on a glass wafer to form a photosensitive film with a thickness of 0.5 μm, and the photosensitive characteristics were measured when irradiated with T-rays. did. The results are shown in Figure 1A. In addition, as a comparative example, the results of the photosensitive characteristics when using a photosensitive solution prepared with the above-mentioned paratertiary butylphenol at 0.2f are shown in Figure 1B.
FIG. 1C shows the results of photosensitivity when using a photosensitive solution prepared without adding butylphenol. The photosensitive properties vary greatly depending on the amount of paratertiary butylphenol added, and matching with the photosensitive properties of photoresists using naphthoquinone cyacytosulfonic acid ester or bisazide is possible when the paratertiary butylphenol is 1 to 1 to polystyrene, including the examples. This was the case for the 10 weight section. When the content is less than 1 inch, the photosensitive speed is too high and the initial light-shielding ability cannot be fully utilized, and when the content is more than 10 inches, the photosensitive speed is too low and extreme exposure energy is required.

Next, this photoresist film formed on the photoresist has a numerical aperture of 0.
．． The resist pattern was exposed using a No. 35 10:1 reduction projection exposure apparatus, and the resist pattern was observed after development. For comparison,
Similar exposure was carried out in the case where no photoresist film was provided. As a result, with the composition of this example, the cross-sectional shape of a pattern of 0.7 .mu.m was well resolved, but when no photoresist film was provided, the resolution was 1.2 .mu.m.

〔Effect of the invention〕

As detailed above, according to the pattern forming method of the present invention, it is possible to form fine patterns stably with high dimensional accuracy by applying a simple method such as conventional ultraviolet exposure technology. , its practical value is extremely great.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing the photosensitivity characteristics when using the photosensitizer composition (A) of the present invention and the photosensitizer compositions (B, C) of comparative examples. Agent Patent Attorney Nori Chika Yudo Kikuo Takehana

Claims (2)

[Claims] (1) On the resist film, there are general formula (1): ▲Mathematical formula, chemical formula, table, etc.▼…………(1) Arylnitrone (in the formula, R and R' are mononuclear aromatic groups) , where n is 0 or 1), and then forming a pattern using a light beam that sensitizes both the resist and the aryl nitrone. ) or (3):
▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(2) ▲There are mathematical formulas, chemical formulas, tables, etc.▼…………(3) (In the formula, R^1 and R^2 are the same hydrogen atoms, halogen atoms, hydroxyl groups,
and at least one of an organic acid represented by a carboxyl group, a sulfo group, an alkyl group having 1 to 5 carbon atoms, an amino group, or a nitro group. (2) The content of organic acid is 1 to 10 relative to polystyrene.
The pattern forming method according to claim 1, characterized in that the amount is % by weight.