JPH01239928A - Formation of pattern - Google Patents

Abstract

PURPOSE:To develop at a time first and second positive resist films by superimposing and applying the second positive type resist film, which is not exposed, on the first positive type resist film after exposing the whole surface of the latter, and selectively exposing both films. CONSTITUTION:A first positive type resist film 12 is formed on a substrate 11 and exposed over the entire surface thereof. A second positive type resist film 13 of the same kind as the first one is superimposed and applied on the first one. Then, those films are selectively irradiated with a light l2 by a projection exposure method to selectively form an optically sensitized region 14 on the second positive type resist film 13. Further, the first and second positive type resist films 12, 13 corresponding to the sensitized region 14 are removed to form an opening 15. With such a construction, upon the second positive type resist film 13 being selectively exposed for forming the opening with use of a development solution, the first positive type resist film 12 is also developed for forming an opening therethrough.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to pattern formation in the manufacture of semiconductor devices.
In particular, the present invention relates to a method of forming a positive resist pattern.

[Conventional technology]

There are various methods for forming a fine mask pattern of 1 to 2 μm or less on a semiconductor substrate, but there is a method for forming a resist pattern with good uniformity, especially on a substrate with steps, as described in JP-A-58-132926. There is something. This will be explained with reference to FIG. First, the positive resist 20 is irradiated with light. (ultraviolet rays) to make it soluble in the subsequent developer (Fig. 2 (α)). Next, the positive resist 20 is applied onto a substrate 21 such as a semiconductor substrate or a thin film having a flat or uneven surface to form a first positive resist film 22 (FIG. 2(b)).

The thickness of the resist film 22 is formed to be thicker than the unevenness of the substrate 21. Here, the surface of the resist film 22 does not necessarily have to be flat, but is preferably flat. Next, apply a positive resist (25) to the first positive resist (1l12) using optical irradiation.
2 (Fig. 2(c)). At this time, the first
Since the same type of resist films 22 and 23 are used as the second positive resist films 22 and 23, the first and second resist films 22.
The interface of 25 is not clear. Next, light irradiation t4 is selectively performed using a projection exposure method to selectively form photosensitive regions 24 on the resist film 23 (FIG. 2(d)). Next, the photosensitive area 2 is developed and rinsed for 1 positive resist.
The first and second resist films 22 and 25 of No. 4 are selectively removed to form an opening 25 (FIG. 2(e)). Then, the substrate 21 is etched using the patterns of the first and second resist films 22 and 23.

According to the above method, as shown in FIG. 2(α), the first resist film 22 is coated using a positive-type resist film 20 that has been exposed in advance, so that the remaining resist in the openings 25 is removed. This eliminates the possibility of different pattern widths. In addition, the first resist film 22 has the effect of flattening the substrate 21, so the thickness of the second resist film 23 becomes almost uniform regardless of the unevenness of the substrate 21, and with a constant exposure amount. Pattern formation can be performed with high precision.

[Problems to be Solved by the Invention] J However, in the above-mentioned method, the step of exposing the body type resist in advance to light is increased, and an additional line for applying the exposed resist is required.

In addition, with conventional methods, a large amount of resist is exposed all at once, making it difficult to uniformly expose positive resist.
Moreover, impurities were mixed in and deteriorated the characteristics of the resist.

Therefore, the present invention is intended to solve such problems,
The purpose of this method is to eliminate the need to expose the resist to light in advance, and to form fine patterns with high precision using only existing resist coating lines and with a higher throughput than conventional methods.

[Means to solve the problem]

The pattern forming method according to the present invention includes a step of applying a positive resist onto a substrate to form a first positive resist film, and a step of exposing the entire surface of the first positive resist film to light. selectively irradiating an unexposed second positive resist film with light on the first positive resist film;
The method is characterized in that it further includes a step of selectively removing the first and second positive resist films by a development process to form a resist pattern.

[Effect]

According to the above configuration of the present invention, the first positive resist I
By exposing the entire surface of N in advance, the second positive resist film is selectively exposed, and when opening holes with a developer,
The first positive resist film can also be developed and opened at the same time.

〔Example〕

Hereinafter, the configuration of the present invention will be explained using the drawings.

FIG. 1 is a process sectional view showing an embodiment of the present invention. First, a first positive type film is formed on a substrate 11 such as a semiconductor substrate or a thin film having a flat or uneven surface. J
12 is formed, and the entire surface is exposed using an exposure device (see Fig. 1 (
α)). Regis) I! The film thickness of s12 is formed to be thicker than the unevenness of the substrate 11. Here, the surface of the resist film 12 does not necessarily have to be flat, but is preferably flat. Next, a second positive resist film 13 is applied over the first positive resist film 12 (FIG. 1(b)). At this time, since the same type of film is used as the first and second positive resist films 12 and 15, the first and second positive resist films 12 and 15 are the same type. 12, 1! The interface of l is not clear. Next, selective light irradiation t is performed using a projection exposure method to selectively form photosensitive areas 14 on the resist film 13 (see FIG.
C)). Next, by developing and rinsing the positive type resist of an appropriate size, the first and second positive type resists 12 and 15 in the photosensitive area 14 are selectively removed, and the openings 15 are formed (the first and second positive type resists). Figure 1 (d)). Then, using the patterns of the first and second positive resist films 12 and 13, the substrate 1 is
1. Etching processing etc. are performed.

[Effects of the Invention] As described above, according to the present invention, after forming the first positive resist film on the substrate, in order to perform full-surface exposure, the resist is exposed in advance as in the conventional method, and this There is no need to set up a line for applying exposed resist,
It is possible to obtain the same effect as the conventional method. That is, since a positive resist film that has been exposed to light in advance is formed on the substrate surface, the resist film can be accurately removed by development and rinsing regardless of the difference in film thickness above and below the step. Therefore, in the present invention, a fine pattern can be formed with high accuracy regardless of the difference in film thickness above and below the step. Furthermore, the present invention allows pattern formation to be performed with high accuracy at a constant exposure amount, regardless of variations in the film thickness of the resist film due to metal films with high reflectance and substrate steps. Furthermore, although the resist film is coated twice, pattern formation can be performed by one development and rinsing treatment, which is an excellent effect.

It goes without saying that the present invention is applicable to pattern formation in all processes including wiring formation processes and contact hole formation processes.

[Brief explanation of the drawing]

FIGS. 1(α) to Cd) are process cross-sectional views showing a pattern forming method according to an embodiment of the present invention. FIGS. 2(α) to 2(g) are process cross-sectional views showing a pattern forming method according to a conventional example. 11.21... Semiconductor substrate 12.22... First positive resist film 13.
23...Second positive resist film 14.24.
. . . Photosensitive area 15.25 . . . Opening portion 20 . . . Positive resist 1, . 1. ．． 1
8,1.・・・・・・Light irradiation barb 1 and 1 Isamu 2

Claims (1)

[Claims] In a pattern forming method in manufacturing a semiconductor device, a step of applying a positive resist onto a substrate to form a first positive resist film, and a step of exposing the entire surface of the first positive resist film to light, After forming an unexposed second positive resist film on the first positive resist film,
A step of selectively irradiating the second positive resist film with light, and a step of selectively removing the first and second positive resist films by a development treatment to form a resist pattern. A pattern forming method characterized by: