JPH03235948A - Formation of fine pattern - Google Patents

Abstract

PURPOSE:To improve the contrast of an optical image at the time of lower patterning layer exposure by forming a phase shifter which inverts the phase of entire-surface irradiating light for lower layer exposure by 180 deg. in the pattern of an upper patterning layer. CONSTITUTION:The lower pattern layer 2 and upper patterning layer 1 are formed on a substrate 3 and a fine pattern is formed on the upper patterning layer 1. Then the 180 deg. phase shifter 9 is formed in the pattern of the upper patterning layer 1 AND A 180 deg.+ or -20 deg. phase shifter 10 is formed at its center part. Consequently, the optical image at the time of lower layer exposure pass ing through the 180 deg. phase shifter part 9 and 180 deg.+ or -20 deg. phase shifter parts 10 and 11 is increased in rectangularity and the fine pattern with higher resolution can be formed. Consequently, the contrast of the optical image at the time of the exposure of the lower pattern layer 2 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for forming fine patterns.

[Conventional technology]

5 to 7 and 9 are cross-sectional views of a semiconductor device shown in accordance with the steps of a conventional fine pattern forming method, and FIG. 8 is a graph showing the optical image intensity distribution in the state shown in FIG. 7. In the figure, (1) is the upper patterning layer;
(February: lower patterning layer, (3) is the substrate, (4) is the mask for upper layer patterning, (5) is the upper patterning light, (6) is the entire surface irradiation light for lower layer exposure, (7) is lower layer exposure Optical image (8) shows the lower layer pattern after development.

Next, a method for forming a fine pattern will be explained.

First, as shown in FIG. 5, a lower patterning layer (2) for flattening and patterning is formed on the substrate (3), and a fine pattern is formed on the lower patterning layer (2),
[An upper patterning layer (1) which becomes a mask layer when exposed to light is formed by coating. Next, the upper layer patterning mask (4) and the upper layer patterning light (5) shown in FIG.
) to pattern the upper patterning layer (1). Next, as shown in FIG. 7, the lower patterning layer (2) is exposed using lower layer non-lighting entire surface irradiation light (6). The upper patterning layer (1) absorbs the entire surface irradiation light (6) for lower layer exposure, and functions as a mask. The optical image (7) at the time of lower layer exposure is as shown in FIG. The pattern after development of the lower patterning layer (2) is as shown in the lower pattern (8) after development shown in FIG.

[Problem to be solved by the invention]

Conventional fine pattern formation methods are carried out as described above, but as the pattern density of the upper patterning layer increases, there are problems such as a decrease in the contrast of the optical image of the diffracted light during exposure of the lower patterning layer. there were.

This invention was made to solve the above-mentioned problems, and aims to provide a fine pattern forming method that improves the contrast of an optical image when exposing a lower patterning layer.

[Means to solve the problem]

In the fine pattern forming method according to the present invention, the phase of the entire surface irradiation light for lower layer exposure is set to 18 in the pattern of the upper patterning layer.
A phase shifter is formed to invert 00.

[Function] In the phase shifter of the present invention, a part of the entire surface irradiation light for exposing the lower layer is phase-inverted by 180°, so that the contrast of the optical image when the lower patterning layer is exposed can be improved.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
2 and 2 are cross-sectional views of a semiconductor device shown according to the steps of the fine pattern forming method, FIG. 3 is a graph showing the optical image intensity distribution when the lower patterning layer shown in FIG. 2 is exposed, and FIG.
The figure is a graph showing the optical energy distribution according to the optical image of FIG.

In the figures, (1) to (3) and (7) are the same as those shown in the conventional examples of FIGS. 5 to 8, and therefore their explanations will be omitted. (9) C180' phase shifter section, QO, αl)
(c) 180°±20° phase shifter section, (b) [Yo indicates optical energy.

Next, a method for forming a fine pattern will be explained.

First, as shown in FIG. 1, a lower patterning layer (2) and an upper patterning layer (1) are formed on a substrate (3).
A fine pattern is formed on the upper patterning layer (1).

Next, in the PCM method lithography, as shown in Fig. 2, 180° between the patterns of the upper patterning layer (1)
A phase shifter (9) is formed, with a 180° ±
200 phase shifter portions are formed. In that case, the diffraction index is the wavelength of the entire surface illumination light (6) for exposing the lower layer.

180° phase shifter part (9), 180'+20° phase shifter part (IQ.

The optical image (7) during lower layer exposure that has passed through aυ becomes highly rectangular as shown in Figure 3, and the optical energy 4 becomes as shown in Figure 4, making it possible to form fine patterns with higher resolution. Become.

180° phase shifter section (9), 18°±20' phase theater section αq.

The material for Oυ should be one that does not absorb the entire surface irradiation light (6)ζ for lower layer exposure, and may be an oxide film such as SOG.

In addition, a 180° phase shifter section (9) and an iso±20' phase shifter Q (J, C1υ
A similar effect can be obtained by forming by etching.

〔Effect of the invention〕

As described above, according to the present invention, since the phase shifter portion is formed during pattern formation of the upper patterning layer, the contrast of the optical image during exposure of the lower layer is improved and a resist image with high rectangularity can be obtained.

[Brief explanation of drawings]

1 and 2 are cross-sectional views of a semiconductor device shown according to the steps of a fine pattern forming method according to an embodiment of the present invention;
FIG. 3 is a graph showing the optical image intensity distribution during exposure of the lower patterning layer shown in FIG. 2, FIG. 4 is a graph showing the optical energy distribution due to the optical image in FIG. 3, and FIGS.
9 and 9 are cross-sectional views of a semiconductor device shown in accordance with the steps of a conventional fine pattern forming method, and FIG. 8 is a graph showing the optical image intensity distribution in the state shown in FIG. 7. In the figure, (1) is the upper patterning layer, (2) is the lower patterning layer, (3) is the substrate, (7) is the optical image at the time of lower layer exposure, (9) is the 180° phase shifter section, OO, αυ
is a 18°±200 phase shifter section, and (b) is optical energy. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] In the PCM two-layer resist method in the light exposure process in lithography technology for semiconductor manufacturing, a 180° phase shifter is formed between the patterns of the upper patterning layer, and a 180° ± 20° phase shifter is formed in the center of the shifter. Featured fine pattern formation method.