JPS60110120A - Pattern formation - Google Patents

Abstract

PURPOSE:To form a high precision resist pattern on a substrate having the stepped portion by forming patterns on a thin film of upper layer by the far ultra-violet ray exposure or electron beam exposure and thereafter irradiating such pattern with the far ultra-violet ray with the upper thin layer used as the mask and developing the pattern. CONSTITUTION:A semiconductor substrate 1 having the stepped portion is coated with polymethylmethacrylate (PMMA) resist 2 and is then subjected to the prebaking. The surface is then coated with resist chloromethylpolysthylene (CMS) 3 for negative electron beam and is then subjected to the prebaking. The surface is exposed with the light source in wavelength of 250nm and a pattern is formed on the CMS resist 3 by the development of isoamyl acetate ethylalsorbu=1:3. Next, the surface is exposed using said light source with the pattern of CMS resist 3 used as the mask. The patterning to the PMMA resist 2 is completed by developing the pattern with the developer of MIBK (methylisobutylketon):IPA (isopropylalcohol)=3:1.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a pattern forming method.

Conventional Structures and Problems As semiconductor devices become finer, variations in pattern width of resist patterns on stepped substrates have become a problem. In order to solve this problem, a two-layer resist method has been proposed. In the conventional two-layer resist method, a far ultraviolet resist is first applied as a lower layer resist on the substrate, and then a normal ultraviolet resist is applied as an upper layer resist. Apply. Next, a pattern is formed on the upper resist by exposing and developing using ultraviolet rays.

Furthermore, by using this upper layer resist as a mask, exposure to deep ultraviolet rays is performed, and development is performed to pattern the lower layer resist, thereby creating a two-layer resist pattern.

This method does not allow patterning of the upper layer resist using deep ultraviolet exposure or electron beam exposure that allows high-definition processing, and is therefore not suitable for ultra-fine processing of semiconductor devices and the like.

For these reasons, it has been desired to form a pattern on a stepped substrate by deep ultraviolet exposure or electron beam exposure.

Purpose of the Invention The present invention solves this problem, and the purpose of the present invention is to provide a pattern forming method for forming a high-definition resist pattern on a stepped substrate using deep ultraviolet exposure or electron beam exposure. That is.

Structure of the Invention The present invention involves forming a two-layer thin film on a substrate, forming a pattern on the upper thin film using deep ultraviolet light or electron beam light, and then forming a pattern on the upper thin film.
This pattern forming method is characterized by forming a pattern by irradiating far ultraviolet light using the upper thin film as a mask.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

PM14A (
Polymethyl methacrylate) resist 2 was applied to a thickness of 1 μm and prebaked at 170° C. for 130 minutes. On top of that, a negative electron beam resist CMS (norolomethylated polystyrene) 3 is applied to a thickness of 0.5 μm and prebaked at 120°C for 530 minutes (Figure 1a).
.

Next, it is exposed for about 1 minute using a light source with a wavelength of 250 nm and an optical output of 10 m'V/c, and is developed with isoamyl acetate ethyl altrubourethane (1=3) to form a pattern on the 0MS resist 3 (see Figure 1). b).

Note that the sensitivity of Plv1MA resist 2 to the above light source is about 1/6 times that of 0MS resist 3, so when forming the pattern of 0MS resist 3, PMM
No pattern is formed on the A resist 2. Experience has shown that it is sufficient if the sensitivity to the light source is less than or equal to PMMA/CM, S.=1/. When PMMA resist 2 was developed for 1 minute using the above-mentioned holding solution, the film loss was 100 Å or less.

Next, the pattern of the OMS resist 3 is masked and exposed for about 10 minutes using the above light source. Here, the PMMA resist 2 directly below the pattern of the 0MS resist 3 is not exposed. The reason for this is that 0MS resist 3 is shown in Figure 2.
After exposure to far ultraviolet rays, 0MS resist 3 has a transmittance of 3 or less and serves as a light shielding mask for PMMA resist 2. Next, MIBK (methyl isobutyl ketone) :IPA(
Knotter/Jung on the PMMA resist 2 is completed by developing for 1 minute with a developer of 3:1 (isozorobyl alcohol) (Fig. 1C). Note that the pattern of the upper layer 0MS resist 3 is If the development is carried out for more than 1 minute, the PMMA resist 2 will be formed into an opart ring shape (FIG. 1d). The amount of overturning can be arbitrarily set by controlling the thickness of the lower resist film and the development time.

In this embodiment, the upper resist layer is turned by deep ultraviolet exposure, but the upper resist layer can also be patterned by electron beam exposure.

Effects of the Invention As detailed above, the present invention involves forming a two-layer thin film on a substrate, forming a pattern on the upper thin film using deep ultraviolet transmittance or electron beam exposure, and then masking the upper thin film. This is a pattern forming method characterized by irradiation with far ultraviolet rays and development, and by using the present invention, a high-definition resist pattern or an optical pattern can be formed on a stepped substrate using deep ultraviolet ray exposure or electron beam exposure. parts can be formed.

[Brief explanation of the drawing]

FIG. 1 a = d is a cross-sectional view for detailed explanation of the present invention, and FIG. 2 is a characteristic diagram showing the relationship between deep ultraviolet light transmittance and deep ultraviolet light irradiation time of 0MS resist. ...Substrate, 2...PMMA resist, 3...0MS resist. Name of agent: Patent attorney Toshio Nakao and one other personff
Figure 11 Figure 2 Irradiation time (9)

Claims (1)

[Claims] (1) After forming a two-layer resist film on a substrate and forming a pattern on the upper resist film using deep ultraviolet rays or an electron beam, deep ultraviolet light is applied to the lower resist film using the upper resist film as a mask. A pattern forming method characterized by forming the two-layered pattern by irradiating and developing. (Success: The far-UV transmittance of the upper resist film is less than 10% of the far-UV incident intensity, and the sensitivity is 1% of that of the lower resist film.)
2. The pattern forming method according to claim 1, wherein the pattern forming method is 0 times or more. (→) The pattern forming method according to claim 1, wherein the openings in the lower resist film are larger than the openings in the upper resist layer and have an undercut shape.