JPH05134384A - Formation of reticule - Google Patents

Abstract

PURPOSE:To obtain the method for forming the reticule which can effectively exhibit the effect of a phase shift and can improve resolving power by forming light shielding films with good accuracy relating to the method of forming the reticule improved in the resolving power by the self-aligning type phase shift. CONSTITUTION:This method is constituted by including a stage for side etching light shielding films 7c, 7d by an etching liquid with pattern films 8a, 8b and phase transition films 6a, 6b of photosensitive films as a mask in such a manner that light shielding films 7e, 7f of a 1st width remain, a stage for drying the pattern films 8a, 8b, light shielding films 7e, 7f, and phase transition films 6a, 6b of the photosensitive films and a stage for side etching the light shielding films again by the etching liquid in such a manner that the light shielding films 7a, 7f of the 2nd width narrower than the 1st width remain.

Description

Detailed Description of the Invention

(Table of contents) -Industrial application field-Conventional technology (Fig. 4) -Problems to be solved by the invention-Means for solving the problem-Action-Examples (Figs. 1 to 3) -Invention Effect of

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a reticle, and more particularly, it relates to a method for producing a self-aligned phase shift reticle in which resolution is improved by phase shift.

[0003]

2. Description of the Related Art In recent years, as the density of semiconductor integrated circuit devices has increased, finer patterns have been required and have a width of 0.3 to 0.5 .mu.m.
It is necessary to form a resist pattern of a certain degree.

To achieve this, a phase shift reticle is used in order to improve the resolution at the time of exposure.
FIG. 3 is a diagram illustrating a structure of a self-aligned phase shift reticle and an exposure method using the self-aligned phase shift reticle. In the figure, reference numeral 1 is a transparent substrate, 2a and 2b are phase conversion films selectively formed so as to correspond to mask patterns to be formed on the transparent substrate 1, and 3a and 3b are adjacent mask patterns. Are separated,
In addition, the light shielding film is formed on the phase conversion films 2a and 2b with a width such that the exposure light is appropriately offset by the phase shift.

When exposure is performed using such a self-aligned phase shift reticle, the exposure light that spreads to the area that should not be irradiated at the boundary between the area that should be irradiated and the area that should not be irradiated due to the nature of light, Passing through the phase conversion films 2a and 2b,
It is canceled by the exposure light whose phase is shifted by 180 °,
The difference in strength at the boundary becomes large. This improves the resolution.

FIGS. 4A to 4E are sectional views for explaining a conventional method of manufacturing the above-described self-aligned phase shift reticle. First, as shown in FIG. 4A, the phase conversion film 2a and the light shielding film 3a are sequentially formed on the transparent substrate 1. Next, after forming a resist film on the light-shielding film 3, the resist film is patterned to form a resist pattern film 4a,
4b is formed.

Next, the light shielding film 3 and the phase conversion film 2 are sequentially etched and removed using the resist pattern films 4a and 4b as masks (FIGS. 4B and 4C). Then, FIG.
As shown in (d), the resist pattern films 4a and 4b and the phase conversion films 2a and 2b are used as masks to shield the light-shielding films 3c and 3c.
3d is side-etched with an etching solution to leave the light-shielding films 3a and 3b having a desired width.
a and 3b are formed.

After that, as shown in FIG. 4E, the resist pattern films 4a and 4b are removed to complete a self-aligned phase shift reticle.

[0009]

By the way, FIG. 4 (d)
As shown in FIG. 5, when side-etching the light-shielding films 3c and 3d with an etching solution, the goodness of adhesion between the light-shielding films 3c and 3d and the resist pattern films 4a and 4b and the goodness of circulation of the etching solution influence the etching. That is, the light shielding film 3
When the adhesiveness between c and 3d and the resist pattern films 4a and 4b is poor, the etching solution permeates and the shape of the pattern films 3a and 3b of the light shielding film is deteriorated. When the removed portion of the light shielding films 3c and 3d between the phase conversion films 2a and 2b and the resist pattern films 4a and 4b is narrow, an old etching solution and a new etching solution which enter the removed portion and complete the etching reaction are used. Therefore, the controllability is deteriorated due to the destabilization of the etching rate. Therefore, there is a problem in that the phase conversion region having a desired width cannot be formed on the reticle, and as a result, the effect of the phase shift cannot be sufficiently exhibited.

The present invention has been made in view of the above problems of the prior art, and is a method for producing a reticle in which a light-shielding film is accurately formed and the effect of phase shift is sufficiently exerted to improve the resolution. It is intended to provide.

[0011]

[Means for Solving the Problems] The first object is to form a phase conversion film and a light-shielding film on a transparent substrate in sequence, and after forming a photosensitive film on the light-shielding film, Patterning the film to form a pattern film of the photosensitive film, etching and removing the light shielding film and the phase conversion film using the pattern film of the photosensitive film as a mask, the pattern film of the photosensitive film and the phase A step of side-etching the light-shielding film with an etching solution so that the light-shielding film having a first width remains with the conversion film as a mask, and a step of drying the pattern film of the photosensitive film, the light-shielding film, and the phase conversion film. And using the pattern film and the phase conversion film of the photosensitive film as a mask, side-etching the light-shielding film again with an etching solution so that the light-shielding film having a second width narrower than the first width remains. Be achieved by creating a reticle with bets, the second, the phase conversion film is an SOG film or SiO ₂ film, and the light-shielding film is one or more layers of a film containing at least chromium (Cr) film, The photosensitive film is a resist film, and the etching solution is ceric ammonium ammonium nitrate.

[0012]

According to the method for producing a reticle of the present invention, the phase conversion film, the light shielding film and the photosensitive film are dried during the side etching of the light shielding film.

Therefore, the etching liquid entering the interface between the phase conversion film and the light-shielding film and the interface between the light-shielding film and the photosensitive film can be removed. It is possible to prevent deterioration of the shape of the pattern film. In addition, since the old etching solution that has entered the removed portion of the light shielding film between the phase conversion film and the photosensitive film and finished the etching reaction can be removed and a new etching solution can be supplied to the etching portion, Stabilization can be achieved. As a result, the light-shielding film is formed with high accuracy, the effect of the phase shift is sufficiently exerted, and the resolution can be improved.

[0014]

EXAMPLES FIGS. 1 (a) to 1 (e), FIGS. 2 (f) and 2 (g)
FIG. 6A is a cross-sectional view illustrating a method of manufacturing a self-aligned phase shift reticle according to an embodiment of the present invention.

First, as shown in FIG. 1A, a film thickness of about 0.4 μm is formed on a transparent substrate 5 made of synthetic quartz by a coating method.
The phase conversion film 6 made of the SOG film is formed. The phase conversion film 6 is formed so as to satisfy the film thickness (t) t = λ / 2 (n−1), where λ: wavelength of exposure light n: refractive index of the phase conversion film 6.

Next, a light shielding film 7 made of a chromium (Cr) film having a film thickness of about 1000 Å is formed on the phase conversion film 6 by sputtering. As the light-shielding film 7, a two-layer film of lower Cr film / upper chromium oxide (CrO) film can be used.

Next, after forming a resist film on the light-shielding film 7, the resist film is patterned to form resist pattern films (photosensitive film pattern films) 8a, 8 having a width of about 1.5 μm.
b is formed.

Next, as shown in FIG. 1B, CCl ₄ gas or C is used with the resist pattern films 8a and 8b as masks.
The light shielding film 7 is etched and removed by a dry etching method using H _{2 C} Cl ₂ gas.

Subsequently, as shown in FIG. 1C, the phase conversion film 6 is etched and removed by a dry etching method using CF ₄ gas with the same resist pattern films 8a and 8b as a mask.

Next, as shown in FIG. 1 (d), the light shielding films 7c and 7d are respectively removed on both sides by an etching solution containing cerium ammonium nitrate using the resist pattern films 8a and 8b and the phase conversion films 6a and 6b as masks. 0.2
Side etching is performed by about μm to leave the light shielding films 7e and 7f having a width of about 1.1 μm.

Next, as shown in FIG. 1 (e), the transparent substrate 1 is placed in a constant temperature bath at a temperature of about 110 ° C., heated for about 60 minutes, and dried. As a result, the etching liquid that has entered the interfaces between the phase conversion films 6a and 6b and the light shielding films 7e and 7f and the interfaces between the light shielding films 7e and 7f and the resist pattern films 8a and 8b is removed, and at the same time, the phase conversion films 6a and 6b and resist pattern films 8a, 8b between light-shielding films 7c, 7d
The old etching solution which has entered the removal portion of and has finished the etching reaction is removed.

Then, as shown in FIG. 2 (f), again,
Resist pattern films 8a and 8b and phase conversion films 6a and 6
Using b as a mask, the light-shielding films 7e and 7f are further side-etched by about 0.3 μm on each side with an etching solution containing cerium ammonium nitrate, and the width is about 0.5 μm.
m light-shielding films 7a and 7b are left and the pattern film 7 of the light-shielding film
a and 7b are formed.

After that, as shown in FIG. 2G, the resist pattern films 8a and 8b are removed to complete the self-aligned phase shift reticle. A method of performing exposure using the reticle thus created will be described with reference to FIG. That is, the exposure light that spreads in the region that should not be irradiated at the boundary between the region that should be irradiated and the region that should not be irradiated due to the nature of light passes through the phase conversion films 6a and 6b,
It is canceled by the exposure light whose phase is shifted by 180 °,
The difference in strength at the boundary becomes large. This improves the resolution.

As described above, according to the reticle manufacturing method of the present invention, as shown in FIG. 1 (e), the light shielding films 7e and 7e are formed.
During the side etching of f, the phase conversion films 6a, 6b,
The light shielding films 7e and 7f and the resist pattern films 8a and 8b are dried.

Therefore, the phase conversion films 6a and 6b and the light shielding film 7
It is possible to remove the etching liquid that has entered the interfaces between the light-shielding films 7e and 7f and the light-shielding films 7e and 7f and the resist pattern films 8a and 8b. It is possible to prevent deterioration of the shapes of 7a and 7b. In addition, the old etching solution which has entered the removed portion of the light shielding films 7c and 7d between the phase conversion films 6a and 6b and the resist pattern films 8a and 8b and which has finished the etching reaction is removed, and a new etching solution is supplied to the etching portion. Therefore, the etching rate can be stabilized. As a result, the pattern films 7a and 7b of the light-shielding film are formed with high accuracy, the effect of the phase shift is sufficiently exhibited, and the resolution can be improved.

In the embodiment, as the phase conversion film 6, S is used.
Although the OG film is used, a SiO ₂ film or other film may be used. Further, the drying is performed once during the etching, but may be performed twice or more.

[0027]

As described above, according to the reticle manufacturing method of the present invention, the phase conversion film, the light shielding film and the photosensitive film are dried during the side etching of the light shielding film.

Therefore, the etching solution that has entered the interface between the phase conversion film and the light-shielding film and the interface between the light-shielding film and the photosensitive film and the removed portion of the light-shielding film between the phase conversion film and the photosensitive film are etched. Since the old etching solution that has finished the reaction can be removed, the deterioration of the shape of the pattern film of the light-shielding film due to the penetration of the etching solution into these interfaces can be prevented, and a new etching solution can be supplied to the etching area for etching. It is possible to stabilize the rate. As a result, the light-shielding film is formed with high accuracy, the effect of the phase shift is sufficiently exerted, and the resolution can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view (No. 1) for explaining a method for producing a reticle according to an embodiment of the present invention.

2A and 2B are cross-sectional views (No. 2) for explaining the method for producing the reticle according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating an exposure method using a phase shift reticle.

FIG. 4 is a cross-sectional view illustrating a method of manufacturing a reticle of a conventional example.

[Explanation of symbols]

5 transparent substrate, 6, 6a, 6b phase conversion film, 7, 7c to 7f light shielding film, 7a, 7b pattern film of light shielding film, 8a, 8b resist pattern film (pattern film of photosensitive film).

Claims (2)

[Claims] 1. A step of sequentially forming a phase conversion film and a light shielding film on a transparent substrate; forming a photosensitive film on the light shielding film; then patterning the photosensitive film to form a pattern film of the photosensitive film. A step of forming, a step of etching and removing the light-shielding film and the phase conversion film by using the pattern film of the photosensitive film as a mask, and a step of using the pattern film of the photosensitive film and the phase conversion film as a mask by the first width Side-etching the light-shielding film with an etching solution so that the light-shielding film remains; drying the pattern film, the light-shielding film, and the phase conversion film of the photosensitive film; Using the film as a mask, a step of side-etching the light-shielding film again with an etching solution so that the light-shielding film having a second width narrower than the first width remains, and a method for producing a reticle. 2. The phase conversion film is an SOG film or a SiO ₂ film, the light-shielding film is one or more layers containing at least a chromium (Cr) film, and the photosensitive film is a resist film. The method for producing a reticle, wherein the etching solution is ceric ammonium nitrate.