KR20020007510A - Photomask - Google Patents

Abstract

PURPOSE: A photomask is provided to prevent the intensity of the light passing through a space region from being excessively increased so that the profile of a photoresist layer pattern confining a fine contact hole and the space region is optimized by a photolithography process, by forming a mask region in the space region of the photomask having a line/space pattern and a contact pattern. CONSTITUTION: A mask material pattern(31) is formed on one surface of a transparent substrate(30), composed of the line/space pattern(35) and the contact pattern(36). The line/space pattern has at least one mask region covering a predetermined region of the space region(32) of the line/space pattern.

Description

Photomask {PHOTOMASK}

The present invention relates to a photomask, and more particularly, to a photomask for forming a line / space pattern and a contact pattern together.

Various patterns of semiconductor devices are formed by lithography technology. Lithography techniques are classified into light lithography using light, electron beam lithography using electron beam (E-Beam), and X-ray lithography using X-ray.

The process of forming a pattern by the optical lithography technique most commonly used is as follows. First, an insulating film or a conductive film to form a pattern is formed on the semiconductor substrate. Second, a photosensitive film whose solubility is changed by irradiation with light such as ultraviolet rays is formed. Third, after a predetermined portion of the photoresist film is exposed to light, a portion having high solubility is removed through a developing process to form a photoresist pattern. Fourth, an insulating film, a conductive film or the like exposed by the photosensitive film pattern is etched using the photosensitive film pattern as an etch stop film. Fifth, the photosensitive film pattern is removed to form various patterns such as wiring and electrodes.

The process of forming the photoresist pattern of the third step must be the key element in the optical lithography technology. The rapid development of semiconductor technology requires more diverse and fine patterns. In order to form such a pattern, a photomask pattern for selectively transmitting light rays only to a predetermined portion of the photosensitive film is required. The photomask is produced by forming a photomask pattern made of a light blocking material such as Cr on a transparent quartz substrate.

Common photomask patterns include a line / space pattern and a contact pattern. The line / space pattern is rectangular in shape and longer in length than the other in which one side is vertical. When patterning is performed on the photoresist by the line / space pattern of the photomask, the remaining portion of the photoresist becomes a photoresist line pattern, and the space between the photoresist line patterns becomes a photoresist space pattern. The line / space pattern is used when forming a laminated structure on a semiconductor substrate. The contact pattern is used to connect a stack structure, for example, wirings on a semiconductor substrate formed by the line / space pattern in a shape close to a square.

Generally, the line / space pattern and the contact pattern are not formed at the same time. The reason is that in the photolithography process, the intensity of light passing through the photomask pattern shows a significant difference in line / space and contact. Therefore, it is difficult to simultaneously control the intensity of light incident on the photoresist through the line / space pattern of the photomask and the intensity of light through the contact pattern of the photomask, and thus it is difficult to form an accurate photoresist pattern and secure a process margin. to be. However, as various structures are required in a semiconductor integrated circuit, a line / space pattern and a contact pattern need to be formed together.

Hereinafter, the problems of the prior art that occur when the line / space pattern and the contact pattern are formed together with reference to FIGS. 1 and 2 will be described.

Referring to FIG. 1, the photomask 20 includes a transparent quartz substrate 1 and a light blocking material pattern 3 formed on one surface thereof. The light blocking material pattern 3 is formed of an opaque material such as chromium (Cr), and includes patterns that expose a predetermined region of the substrate 1. The light blocking material pattern 3 of the photomask 20 includes a line / space pattern 10 and a contact pattern 11 together. The line / space pattern 10 consists of space regions 7 parallel to each other and line regions 9 between these space regions 7.

Referring to FIG. 2, a predetermined film 15 for forming the line / space pattern 10 and the contact pattern 11 together is formed on the semiconductor substrate 13. Subsequently, a photoresist, for example, a positive photoresist, is applied to the entire surface of the predetermined film 15, and then the photoresist is exposed using the photomask 20 of FIG. 1, and then the exposed photoresist is developed to develop a photoresist pattern 17. ). Accordingly, the line portion 9a, the space portion 7a, and the contact portion 11a corresponding to the line region 9, the space region 7 and the contact pattern 11 of the photomask 20 are defined. The photosensitive film pattern 17 is formed.

Here, when the relationship between the light intensity and the photoresist film is detected, when light intensity is irradiated to a predetermined portion on the photoresist film, light does not sufficiently penetrate to the lower photoresist film, and thus does not react with the photoresist film to change its solubility. This leaves the photoresist film in the subsequent development process without being removed. In addition, when the light intensity is excessively irradiated onto the photoresist film, light penetrates to a region beyond a predetermined portion on the photoresist film to change the solubility of the photoresist film, and thus, it is difficult to implement an accurate photoresist pattern.

The area of the contact pattern 11 of the photomask 20 is relatively smaller than the area of the space area 7 of the line / space pattern 10. That is, the intensity of light passing through the space region 7 is significantly stronger than the intensity of light passing through the contact pattern 11. Therefore, when the light intensity is irradiated under conditions for optimizing the profile of the contact portion 11a of the photosensitive film pattern 17, light passing through the space region 7 is irradiated to the photosensitive film relatively excessively. As a result, the space portion 7a of the photoresist pattern 17 may be excessively expanded and the line portion 9a of the photoresist pattern 17 may become relatively small. In addition, when light is irradiated under conditions for optimizing the line / space pattern 10 of the photomask 20, the contact portion 11a of the photoresist pattern 17 may not be completely formed and a part of the photoresist film remains. In addition, the space region 7 is formed small in the line / space pattern 10 of the photomask 20, and then exposed to light intensity for optimizing the contact pattern 11 to expose the space of the photoresist pattern 17. There is also a way to compensate for the amount by which the portion 7a is expanded. However, even in this case, the profile and the size of the space portion 7a of the photosensitive film pattern 17 are not formed uniformly according to the change of focus, which is one of the exposure process conditions. In particular, when the predetermined film 15 to form the pattern has a step, the profile and the size of the photoresist pattern 17 are extremely unstable due to the change in focus, so that the line portion of the photoresist pattern 17 is subjected to subsequent etching. (9a) is lost and it is difficult to keep the process stable. Due to the above-described problems, the line / space pattern 10 and the contact pattern 11 may not be formed together at the same time, and thus the line / space pattern 10 and the contact pattern 11 are formed independently through two photographic processes. Additional semiconductor manufacturing processes increase productivity.

Therefore, the technical problem to be achieved by the present invention is to create a photomask that can optimize the profile of the contact pattern and the line / space pattern in one photo process while securing process margins without being concerned with exposure conditions such as light intensity and focus. To provide.

1 is a plan view of a photomask in which a conventional line / space pattern and a contact pattern are formed.

FIG. 2 is a cross-sectional view for explaining a step of forming a photosensitive film pattern along the II of FIG. 1. FIG.

3 is a plan view of a photomask in which a line / space pattern and a contact pattern are formed according to the present invention;

4 is a cross-sectional view for explaining a step of forming a photosensitive film pattern along II-II in FIG. 3.

In order to achieve the above technical problem, the present invention includes a light-shielding material pattern formed on one surface of the transparent substrate, wherein the light-shielding material pattern is composed of a line / space pattern and a contact pattern, the line / space pattern is the line And having at least one light shielding area covering a predetermined area of the space area of the / space pattern. The light blocking area is disposed parallel to the longitudinal direction of the space area while passing through the center of the space area, thereby dividing the space area. The width of the light shielding area is preferably smaller than the limit resolution of the photographic process.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 3 and 4. Here, the embodiment of the present invention has been exemplified only in the case of a photomask for using a positive photosensitive film, but the present invention can also be applied to the case of using a negative photosensitive film.

Referring to FIG. 3, the photomask 50 according to the present invention includes a transparent substrate 30 and a light shielding material pattern 31 formed on one surface of the substrate 30. The light blocking material pattern 31 is formed of an opaque material such as chromium (Cr) and includes patterns that expose a predetermined region of the substrate 30. In detail, the light blocking material pattern 31 includes a line / space pattern 35 and a contact pattern 36. The line / space pattern 35 is composed of space regions 32 parallel to each other and line regions 34 between these space regions 32.

As shown in the drawing, the contact pattern 36 may remove the light blocking material to expose the substrate 30. On the contrary, unlike the conventional art, the space area 32 is a rectangular light transmission area 38a and at least one bar-shaped light blocking area 38b crossing the light transmission area 38a. It consists of. Therefore, the intensity of light passing through the space area 32 is reduced by the light blocking area 38b. Accordingly, even if the intensity of light passing through the contact pattern 36 is increased to optimize the profile of the fine contact hole, the phenomenon of excessively increasing the intensity of light passing through the space region 32 can be prevented. have. As a result, the profile of the photoresist pattern defining the space region as well as the fine contact hole can be optimized in one photographing process.

Preferably, the light blocking area 38b is disposed to be parallel to the longitudinal direction of the light transmitting area 38a, thereby dividing the light transmitting area 38a. However, the position and number of the light blocking regions 38b may be modified in various ways depending on the conditions of the photo process to be performed.

4 is a cross-sectional view illustrating a manufacturing process for forming a photoresist pattern on a semiconductor substrate using the photomask 50 of FIG. 3.

Referring to FIG. 4, a material film 42 such as an insulating film, a semiconductor film, or a conductive film is formed on the semiconductor substrate 40. A photoresist, for example, a positive photoresist, is applied onto the material layer 42. After exposing the photoresist using the photomask 50 of FIG. 3, the exposed photoresist is developed to form a photoresist pattern 44. Accordingly, the line portion 34a, the space portion 32a, and the contact portion 36a corresponding to the line region 34, the space region 32, and the contact pattern 36 of the photomask 50 may be defined. The photosensitive film pattern 44 is formed. As described above, when the photoresist pattern 44 is formed using the photomask 50 according to the present invention, the profile of the contact portion 36a, the line portion 34a, and the space portion 32a is formed. All can be optimized. This is because the intensity of light passing through the space region 32 decreases due to the light blocking region 38b even though the intensity of light passing through the contact pattern 36 of the photomask 50 is increased. . The light blocking region 38b reduces only the intensity of incident light and has a size small enough not to form a line pattern due to light blocking on the photoresist pattern 17 due to light diffraction. That is, the width of the light shielding area 38b is smaller than the limit resolution of the photographic process.

In addition, the conditions of the exposure process may implement the pattern of the photomask 50 as the photoresist pattern 44 by various variables such as focus, light irradiation time, type of photoresist film, and thickness of the photoresist film. It is possible to control the light intensity by the light shielding area 38b inserted into the space area 32 of the photomask 50 so as to sufficiently secure the margin of the exposure process in controlling the various exposure condition variables at the same time. Can be.

As described above, the light shielding area is formed in the space area of the photomask in which the line / space pattern and the contact pattern are formed together to prevent an excessive increase in the intensity of light passing through the space area. Therefore, there is an effect that the profile of the photoresist pattern defining the space region as well as the fine contact hole can be optimized in one photo process.

Claims (3)

Transparent substrates; And And a light blocking material pattern formed on one surface of the transparent substrate, wherein the light blocking material pattern includes a line / space pattern and a contact pattern, and the line / space pattern defines a predetermined area of a space area of the line / space pattern. A photomask having at least one light shielding area to cover. The method of claim 1, And the light blocking area is disposed parallel to the longitudinal direction of the space area while passing through the center of the space area, thereby dividing the space area. The method of claim 1, The width of the light shielding region is formed smaller than the limit resolution of the photo process.