JPS63215040A - Method of hardening resist - Google Patents

Abstract

PURPOSE:To obtain a stable effect of hardening, and realize a fine resist pattern of high accuracy, by applying a heating process at a temperature lower than the heat resisting temperature of a resist to the resist before the light radiation for hardening the resist. CONSTITUTION:A resist pattern 2 is formed on the main surface of a substrate 1. By applying a baking treatment as a treatment before UV radiation, a resist pattern 3 for which baking is finished is obtained. The above baking treatment is performed so as to heat the whole resist pattern 2 for 15 min at a temperature of 150 deg.C. By radiating UV rays 6 for 1 min, a UV-irradiated resist pattern 4 is obtained. By applying a baking treatment to heat the whole pattern 4 for 30 min at a temperature of 200 deg.C, a resist pattern 5 subjected to a hardening treatment is obtained. Thereby, a fine resist pattern of high accuracy can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for hardening resist used in the manufacturing process of semiconductor devices.

2. Description of the Related Art Semiconductor devices are progressing toward higher integration and miniaturization of circuits. In line with this, high precision resist patterns are required in the lithography process for forming fine structures of semiconductor devices, and high-resolution exposure techniques and baking treatments that take into account dry etch resistance and the like are important.

For this reason, UV hardening has been attracting attention in recent years as a resist hardening technique.

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of Single 1ayer and multi
layer resist patternsMatt
hews, John 1. Williott, Jr.
1984 5PIE) and (UV hardening equipment 9
It is known to be effective in hardening the resist, as described in the ULSI, July 2013. An example of a standard UV hardening process is explained according to FIG.

First, as shown in FIG. 2a, a resist pattern 2 is formed on a substrate 1 by a well-known lithography technique, and then ultraviolet light (UV light) 6 is irradiated as shown in FIG. A UV irradiation resist pattern 4 is obtained. Then,
As shown in FIG. 2C, after UV irradiation, a baking process is performed to heat the entire resist pattern, thereby obtaining a resist pattern 5 that has been subjected to a hardening process.

Problems to be Solved by the Invention According to the conventional method, during UV hardening of the resist, in addition to the effect of hardening the resist, wrinkles are generated on the resist surface, bubbles are generated in the resist, etc., which are undesirable for the resist. Abnormal phenomena may occur. Therefore, when the conventional method is directly applied to the manufacturing process of semiconductor devices, there is a problem that this UV hardening causes defects.

Incidentally, the generation of wrinkles can be suppressed by baking the substrate while applying UV irradiation, as in the apparatus described in the above-mentioned literature, but it is also possible to suppress the formation of bubbles in the resist. I couldn't hold it back. Particularly, in the hardening method of the present invention, which has been made for the purpose of eliminating the above-mentioned problems, the resist film thickness is set at a temperature lower than the heat resistance temperature of the resist before the light irradiation used for hardening the resist. This method involves adding heat treatment.

Effect: According to the hardening method of the present invention, a stable hardening process can be performed on a fine resist pattern without causing abnormal phenomena.

EXAMPLE The hardening method of the present invention will be explained with reference to FIG. First, as shown in FIG. 1a, a resist pattern 2 is formed on the main surface of a substrate 1 by a well-known photolithography technique. Next, as shown in Figure 1, UV
As a treatment before irradiation, the entire resist pattern is coated with 150%
A baked resist pattern 3 is obtained by performing baking treatment at .degree. C. for 15 minutes. Thereafter, as shown in FIG. 1C, irradiation with UV light 6 is performed for 1 minute to obtain a UV irradiated resist pattern 4. Next, as already shown in FIG. 1, the entire resist pattern is subjected to a baking process in which the resist pattern is heated at a temperature of 200° C. for 30 minutes, thereby obtaining a resist pattern 5 that has been subjected to a hardening process.

Incidentally, the following may be considered as the cause of the occurrence of resist abnormalities that can be suppressed by performing hardening treatment using such a method. First, wrinkles occur.When the light transmittance of the resist is low, the UV light irradiation becomes uneven along the depth direction of the resist, causing a crosslinking reaction only on the resist surface, causing the surface This occurs due to the formation of a hardened state. However, in the hardening method of the present invention, the baking treatment performed before UV light irradiation removes the solvent, etc. from the resist, and a certain hardening reaction progresses inside the resist, so it is difficult to suppress the generation of wrinkles. can.

Next is the generation of bubbles in the resist. These bubbles occur because when the resist is irradiated with UV light, photodecomposition of naphthoquinone diazide proceeds at the same time as the crosslinking reaction, generating nitrogen. It is considered that

However, in the hardening method of the present invention, by baking before UV irradiation, naphthoquinone diazide, which is a photosensitive group, is thermally decomposed, so the generation of nitrogen during UV irradiation is suppressed, and the generation of bubbles. can be suppressed.

Effects of the Invention According to the present invention, even if various resists are subjected to UV hardening treatment, the occurrence of abnormalities in the resist can be suppressed, and a stable hardening effect can therefore be obtained. This has the effect of increasing precision.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a process diagram for explaining the UV hardening method of the present invention, and FIG. 2 is a process diagram for explaining the hardening method. 1...Substrate, 2...Resist pattern formed by lithography, 3...UV
Resist pattern subjected to baking treatment before irradiation,
4...Resist pattern irradiated with UV, 5.
...Resist pattern subjected to baking treatment after UV irradiation, 6...UV light. Name of agent: Patent attorney Toshio Nakao and 1 other person
Without it? - Formed by lithography 2 beasts and last pattern 3 - UV=, Shooting page processing I! But z7 play cyst pattern 4-'LIV! ! , Izanameda resist pattern 5-uv
＝、W The baking process of the residue has deteriorated and the cyst pattern is shown in Figure 2 (C).

Claims (1)

[Claims] After patterning a resist formed on a substrate, the resist pattern is subjected to baking treatment at a temperature below its heat resistance temperature, and then the resist is irradiated with light containing deep ultraviolet light and ultraviolet light. Hardening method.