KR0137737B1 - Fabrication method of semiconductor device - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, wherein a phase inversion layer pattern directly contacts a quartz substrate when transferred to a wafer using a positive phase inversion mask that can increase the resolution of a pattern than a mask using only chromium patterns. In order to prevent unnecessary patterns from remaining at the edges of the portion, a mask for exposing a portion where the unnecessary patterns remain is manufactured and double exposure to form a device isolation pattern.

Description

Manufacturing method of semiconductor device

1 is a layout diagram illustrating a first mask having a phase inversion pattern on a chromium pattern according to the related art.

FIG. 2 is a layout showing formation of a photosensitive film pattern using the mask of FIG.

3 (a) to 3 (d) are cross-sectional views showing that the photoresist film is exposed using the mask of FIG. 1, and then the photoresist film is exposed again using the mask manufactured by the present invention, and then the process is performed. .

FIG. 4 is a layout diagram showing a second mask made by the present invention for exposing the unexposed photoresist film when using the mask of FIG.

* Explanation of symbols for main parts of drawings *

1: Quartz substrate 2: Chrome pattern

3: Phase inversion layer pattern 4, 6, 13: Photoresist pattern

5: oxide film 7: nitride film

7a: nitride film pattern 9: photosensitive film

9a: Photoresist pattern 10: Silicon substrate

11a: exposed areas 11b, 11b ': non-exposed areas

17: device isolation oxide film 20: first mask

30: second mask

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and in particular, to solve a problem in which unnecessary patterns remain at the edges of a phase shift layer pattern when a pattern is formed using a positive phase shift mask. It is a technique of forming a positive photosensitive film pattern by exposing one more time using a mask.

Conventionally, a mask in which a chromium pattern is formed on a quartz substrate is used. When using a mask in which a chromium pattern is formed as the degree of integration increases, the transmitted light is in phase with each other between adjacent patterns, so that diffraction and interference of light at the boundary of the pattern This becomes worse and the pattern is not separated, resulting in a problem that the resolution is lowered. As a result, a phase inversion mask in which a phase inversion pattern was formed on a chrome pattern in order to fine-fine a fine pattern has emerged.

The phase inversion mask is reversed 180 ° when the wavelength of light coming between the chromium patterns passes through the phase inversion layer, making the phase out of phase between adjacent patterns, thereby minimizing diffraction and interference at the boundary of the pattern. The separation increases the resolution of the fine pattern.

On the other hand, in order to apply the Levenson type, which is effective as a phase inversion mask, in order to form an isolation pattern, a negative photosensitive film had to be used in view of mask characteristics. However, if all the current processes are used for the positive photoresist process, and the phase inversion mask for the negative photoresist film is used, all the processes have to be changed to the negative photoresist process, which adds manufacturing cost and is manufactured by chemical synthesis to expose the process. The negative photosensitive film in which the portion to be left remains inferior to the positive photosensitive film in which the unexposed portion becomes a pattern.

In addition, it is difficult to apply to the actual process due to the change of the pattern size due to the continuous exposure phenomenon after exposure, and in the case of the adjacent pattern, the size adjustment is difficult due to the interference effect when light passes through the same phase. It should be corrected considering the size to be formed.

The prior art of the device isolation process using the phase inversion mask will be described with reference to FIGS. 1 and 2.

FIG. 1 shows the manufacture of a phase inversion mask by a known technique. The phase for a positive photoresist film in which a chromium pattern 2 and a phase inversion layer pattern 3 are formed on the quartz substrate 1. It is a layout diagram which shows a perfect mask. The phase inversion layer pattern 3 may be formed to be spaced apart at regular intervals.

FIG. 2 is a photosensitive film pattern 6 formed on the silicon substrate 10 using the positive phase inversion mask shown in FIG. 1, and passes through the phase inversion layer pattern 3 of the positive phase inversion mask. The high resolution of the photoresist pattern 6 is maintained by the effect of inverting the phase of light by 180 degrees, while the phase inversion of 180 ° occurs at the edge portion where the phase inversion layer pattern 3 is directly applied to the quartz substrate 1. A problem arises in that an unnecessary photosensitive film pattern 4 remains where a portion meets a portion where phase inversion does not occur.

Accordingly, the present invention provides a normal photoresist pattern by exposing a photoresist film using a positive phase inversion mask, and then exposing another mask to expose an unnecessary part to prevent a pattern from remaining in the part. There is this.

A feature of the present invention for achieving the above object is, by applying an oxide film, a nitride film and a photosensitive film on top of a silicon substrate, using a first mask for device isolation provided with a chromium pattern and a phase inversion pattern on a quartz substrate Exposing the unexposed photoresist film during the exposure step with a second mask having a window formed at the edge of the phase inversion pattern directly contacting the quartz substrate, and removing the photoresist film exposed by the developing step. It includes the step of forming a pattern.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 (a) to 3 (d) and FIG. 4 are cross-sectional views illustrating a device isolation pattern forming process using a positive phase inversion mask according to an embodiment of the present invention.

FIG. 3 (a) shows the first mask 20 (line I-I of FIG. 1), which is a device isolation mask, in which the oxide film 5, the nitride film 7, and the photosensitive film 9 are stacked on the silicon substrate 10. FIG. The photosensitive film 9 is exposed to light, and the photosensitive film 9 is exposed to the exposure area 11a and the non-exposure areas 11b and 11b '. Here, the first mask 20 is formed of a chromium pattern 2 for element isolation on the quartz substrate 1 and a phase inversion layer pattern 3 formed on the entire structure. The phase inversion layer pattern 3 ) And the part where phase inversion does not occur at the boundary between the quartz substrate 1 and the part where the phase inversion does not occur, and an unnecessary non-exposed area 11b 'is formed in this part, so that an unnecessary photoresist pattern is formed after the development process. Will remain.

FIG. 3 (b) shows a second mask having a window 17 with the chrome pattern 2 removed from the portion corresponding to the portion in order to expose the photosensitive film 9 of the unnecessary non-exposed area 11b '. 30 is a cross-sectional view showing that the unnecessary non-exposed areas 11b 'of the exposed photosensitive film 9 are exposed by arranging 30 on the silicon substrate 10. FIG. As shown in FIG. 4, the second mask 30 has a chromium pattern 2 formed on the quartz substrate 1 to prevent unnecessary non-exposed areas 11 ′ generated at the boundary of the pattern. It exposes and prevents generation | occurrence | production of an unnecessary photosensitive film pattern.

FIG. 3 (c) shows the photoresist pattern 9a formed by removing the developing process from the photoresist film 9 of the exposure area 11a after the process shown in FIG. 3 (b), and the nitride film exposed by the photoresist pattern 9a. It is sectional drawing which shows that the nitride film pattern 7a was formed by etching (7).

3 (d) shows that after removing the photosensitive film pattern 9a, an oxide film is grown on the silicon substrate 10 by an oxidation process to form an isolation layer 17, and then the nitride film pattern 7a is removed. It is sectional drawing of the state which completed the separation process.

According to the present invention described above, when a photosensitive film pattern is formed using a conventional positive phase shift mask, it is possible to prevent unnecessary photosensitive film patterns from occurring at the edges of the phase shift layer pattern.

Claims (2)

Applying an oxide film, a nitride film and a positive photosensitive film on top of the silicon substrate; A primary exposure process of exposing the photosensitive film using an element isolation type Levenson type phase inversion mask, A second exposure process of exposing the photosensitive film by using an exposure mask provided with a window such that an edge portion of the phase inversion material causing an unnecessary photosensitive film pattern is transmitted during the photolithography process using the phase reversal mask; Developing the photoresist film to form a photoresist pattern for device isolation; Etching the nitride film using the photosensitive film pattern as a mask; Removing the photoresist pattern and forming a device isolation film in a subsequent process. The method of claim 1, The window of the exposure mask is a semiconductor device manufacturing method, characterized in that the chromium is formed on the upper surface of the quartz substrate.