JPS612326A - Formation of resist pattern - Google Patents

Abstract

PURPOSE:To reduce the developing time remarkably by a method wherein a substrate is coated with a resist film to be prebaked and then after selectively irradiated by radiation for exposure, the resist film is further irradiated by ultraviolet rays for development. CONSTITUTION:A mask blank is spin-coated with polyfluoro ethyl alpha, chloroacrylate 0.5mum thick as positive electron rays sensitive resist to be prebaked for 1hr at 180 deg.C. Then after selectively irradiated by electron rays with a dose of 4.4muc/ cm<2> for exposure, the resist film is further irradiated by ultraviolet rays of output 500W, wavelength 2,537Angstrom respectively for one, five and 10min. Finally a resist pattern may be formed on the mask blank by means of developing said four types resist films utilizing methylisobutylketone.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in a method for forming a resist/base turn.

[Technical background of the invention and its problems]

Conventionally, resist patterns have been formed by the following method. First, a resistor is spin coated onto a substrate to be processed, and after removing the solvent, the substrate is baked (f IJ page) at a predetermined temperature and for a predetermined time in order to improve the adhesion between the substrate and the resist film. Subsequently, the resist film on the cooled substrate is selectively irradiated with radiation, for example, an electron beam, at a dose depending on the type of the resist.

Next, a development process is performed to form a desired resist pattern (4 turns).

By the way, in the formation of the resist/base turn described above, for example, when using a positive resist, exposure is performed at a low dose for the purpose of shortening the exposure process. However, when exposure is performed at a low dose, the development time becomes long and the throughput does not increase. Furthermore, since the development is carried out for a long time, film loss in unexposed areas is large, making it difficult to control fine pattern dimensions with high accuracy. As a result, Shistono J? During the etching process in which the turns are mask-tossed, white thread defects are likely to occur, leading to a decrease in yield. Furthermore, during development after exposure, the wettability of the surface of the substrate to be processed with the developing solution is not uniform, so that the dissolution rate varies depending on the location, resulting in variations in the in-plane dimensions of the resist pattern.

For these reasons, methods for shortening development time and improving process throughput include (1) reducing the L/resist film thickness, (11) increasing the temperature of the developer, and a.
ll) It is possible to select a developer with a high dissolution rate. However, adopting these methods °
As it becomes increasingly difficult to control the dimension of 1,000 turns, the film loss of the resist film in unexposed areas becomes even greater, resulting in an increased frequency of occurrence of white thread defects in the etching process. Also,
Dimensional variations caused by non-uniform wetting of the developer to the resist film on the surface of the substrate to be processed cannot be eliminated. The present invention aims to provide a method for forming a resist pattern that achieves uniform dimensions.

[Summary of the invention]

The present invention provides a method for forming a resist pattern by coating and forming a resist film on a substrate, baking it, selectively irradiating the resist film with radiation, and then performing a development process. The gist of this method is to irradiate the resist film with ultraviolet rays before the development process. According to the method of the present invention, as described above, it is possible to significantly shorten the development time and form a resist pattern that achieves uniform dimensions within the surface of the substrate to be processed.

The above-mentioned ultraviolet irradiation is specifically performed after exposure or after prebaking.

Examples of the resist include positive electron beam sensitive resists, photoresists, X-ray sensitive resists, ion beam sensitive resists, and the like.

[Embodiments of the invention]

Examples of the present invention will be described in detail below.

First, 0.5% of polyfluoroethyl α chloroacrylate as a tenon-type beam-sensitive resist was placed on the mask blank.
μm spin coating and prebaking at 180° C. for 1 hour.

Next, an electron beam was applied to the cyst membrane at 44μc/c1n2.
After selectively irradiating and exposing the resist film at a dose of
The irradiation was performed for 10 minutes, 10 minutes, and 20 minutes, respectively. Next, these four types of resist films were developed using methyl isobutyl ketone (MI BK ) at 25° C. to form a resist pattern on the striped blank.

When the relationship between the ultraviolet irradiation time and the development time for the resist film was investigated, the characteristic diagram shown in FIG. 1 was obtained. As is clear from FIG. 1, it can be seen that by performing ultraviolet irradiation treatment before development, the development speed increases, and by increasing the ultraviolet irradiation time, the development speed also increases. This is thought to be due to the fact that by irradiating ultraviolet rays before development, the active energy of dissolution in the developing solution near the surface of the resist film in the exposed area uniformly decreases, thereby increasing the development speed. This can be inferred from the fact that the wettability of the resist film surface improves after irradiation with ultraviolet rays, as shown in FIG.

Further, since only the dissolution activation energy of the exposed area is uniformly lowered, film thinning of the unexposed area is not accelerated by ultraviolet irradiation.

Therefore, according to the present invention, development can be performed in a short time with a low dose, so that the process can be shortened and the fine pattern dimensions can be controlled with high precision.

In fact, as is clear from Figure 3, which shows the relationship between the electron beam dose and the appropriate development time when the ultraviolet irradiation time is constant (10 minutes), the conventional dose of 4.4 μm/cfn2 is suitable. It can be seen that the development time can be significantly shortened in the present invention compared to the development time.

Furthermore, according to this example, it was found that the dimensional error of the resist/base turn within the plane of the mask blank was as small as 0.06 to 0.10 μm. In contrast, in the conventional method, 0.0
9~0.154! The in-plane dimensional error was shown. This excellent effect of the present invention is due to the fact that the developer is uniformly applied within the plane of the mask blank.

〔Effect of the invention〕

As detailed above, according to the present invention, a method for forming a resist/base turn realizes reduction of defects caused by high dosage, improvement of throughput in the development process, and improvement of dimensional accuracy within the substrate plane. can be provided.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing the relationship between UV irradiation time and development time, Figure 2 is a characteristic diagram showing the relationship between UV irradiation time and the contact angle of the UV-treated resist film with water, and Figure 3 is the dose amount. FIG. 3 is a characteristic diagram showing the relationship between the time and the appropriate development time. Applicant's representative Patent attorney Takehiko Suzue Figure 1) ■ Katama Tadarisu / sec Figure 2 Murasaki 9 Haku 9 Guzaimaki Kaisei 1n Figure 3 Dos 1)' - Shiie 2

Claims (2)

[Claims] (1) In the method of forming a resist pattern by coating and forming a resist film on a substrate, baking it, selectively irradiating the resist film with radiation, and then performing a development process, the development process 1. A method for forming a resist pattern, comprising first irradiating the resist film with ultraviolet rays. (2) The method for forming a resist pattern according to claim 1, wherein the resist film is made of a positive electron beam sensitive resist, and an electron beam is used as the radiation.