JPH0547658A - Preventing method for halation of photolithography - Google Patents

Abstract

PURPOSE:To prevent a halation, to improve resolution of a resist film and to form an accurate resist pattern by attenuating an incident light by a reflection preventive film without influence of a surface state and a shape of a pattern. CONSTITUTION:An interlayer film 13 is formed in a state covering a pattern 12 on a substrate 11 in a first step. Then, in a second step, a reflection preventive film 14 is formed on the upper surface of the film 13. Subsequently, in a third step, a resist film 15 is formed on the upper surface of the film 14, and then the resist 15 is photosensing-processed.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for preventing halation in photolithography.

[0002]

2. Description of the Related Art When an interlayer film is formed on a pattern having a high surface reflectance and then a contact hole is formed in the interlayer film on the pattern by ordinary photolithography and etching, the surface of the pattern is usually used. An antireflection film is coated on. As the antireflection film, a titanium nitride film that easily absorbs incident light at the time of exposure in photolithography is used.

[0003]

However, the above method cannot sufficiently reduce the reflected light on the pattern surface during exposure. Usually, when the surface of the antireflection film is not positioned perpendicular to the incident light, the amount of reflection of the incident light increases according to the inclination of the surface of the antireflection film. For example, as shown in FIG. 3, when the pattern 32 is formed on the substrate 31 by an aluminum film by high temperature sputtering, the crystal grain size of the aluminum film is large,
The surface of the pattern 32 becomes uneven. When the antireflection film 33 is formed on the surface of the pattern 32, the surface of the antireflection film 33 also becomes uneven. Therefore, the incident light 6
Since 1 diffusely reflects on the surface of the antireflection film 33, the antireflection effect cannot be sufficiently obtained. As a result, the pattern 32
Halation occurs in the resist film 35 formed on the interlayer film 34 that covers the.

Further, as shown in FIG. 4, when the pattern 42 is formed on the substrate 41 with its surface curved concavely, the antireflection film 43 formed on the surface of the pattern 42.
The light 71 reflected on the surface of the light is condensed, and the intensity of the reflected light 71 is partially increased. Further, even when the convexly curved patterns 44 and 45 are formed on the substrate 41 and in a state of being close to each other, the patterns are reflected on the surfaces of the antireflection films 46 and 47 formed on the respective surfaces of the patterns 44 and 45. The reflected light 72 is condensed, and the intensity of the reflected light 72 is partially increased. Therefore, halation occurs in the resist film 49 formed on the interlayer film 48 that covers the patterns 42 to 44.

As described above with reference to FIGS. 3 and 4,
When halation occurs in the resist film, the resolution of the resist film decreases. Therefore, a highly accurate resist pattern cannot be formed. When the resolution is further deteriorated, the resist pattern is collapsed and pattern formation cannot be performed. As a result, when the interlayer film is etched using the above resist pattern as an etching mask, the accuracy of the pattern formed on the interlayer film is extremely lowered.

An object of the present invention is to provide a method for preventing halation in photolithography.

[0007]

The present invention is a method for preventing halation in photolithography, which has been made to achieve the above object. That is, in the first step, the interlayer film is formed so as to cover the pattern on the substrate. Then, in a second step, an antireflection film is formed on the upper surface of the interlayer film. Subsequently, in a third step, after forming a resist film on the upper surface of the antireflection film, the resist film is exposed to light.

[0008]

In the photolithography antihalation method described above, since the antireflection film is formed on the smooth upper surface of the interlayer film, the antireflection film absorbs most of the incident light without being affected by the unevenness or curvature of the pattern surface. To do. Further, the antireflection film also absorbs light incident on the interlayer film and reflected from the pattern from the interlayer film side. As a result, the amount of reflected light incident on the resist film formed on the interlayer film is significantly reduced, so that halation does not occur in the resist film.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the process diagram of the halation preventing method shown in FIG. 1st as shown in the figure
In the step, the interlayer film 13 is formed so as to cover the pattern 12 formed on the substrate 11. Pattern 12 above
Is made of, for example, an aluminum alloy formed by sputtering. The interlayer film 13 is made of, for example, a SiO ₂ film formed by a chemical vapor deposition method.

Then, in a second step, an antireflection film 14 made of a titanium nitride film is formed on the upper surface of the interlayer film 13 by, for example, a chemical vapor deposition method. The antireflection film 14
In addition to titanium nitride, it can be formed of any other material as long as it is a material that easily absorbs light having a wavelength (for example, G line, I line, ultraviolet ray, etc.) used in a normal exposure process. For example, titanium nitride oxide, selenium germanium chalcogen compound, or the like can be used. Further, the film thickness of the antireflection film 14 is appropriately determined depending on the wavelength and intensity of the incident light beam.

Next, in a third step, a resist is applied to the upper surface of the antireflection film 14 to form a resist film 15.
Then, the reticle 16 is used as a photomask, and the resist film 15 is exposed to light. Then, the exposed resist film 15 is developed to form a resist pattern (for example, a hole pattern) (not shown).

In the above halation prevention method, the upper surface of the interlayer film 13 is usually formed in a substantially smooth state even if the surface of the pattern 12 is uneven. Therefore, the antireflection film 14 formed along the upper surface of the interlayer film 13 is in a position substantially perpendicular to the incident light. Therefore, the resist film 15
The incident light incident on is sufficiently absorbed by the antireflection film 14 and attenuated. As a result, even if the surface of the pattern 12 is formed to be uneven, the incident light reaching the pattern 12 has a small amount of light, so that halation does not occur in the resist film 15.

Even when the pattern 12 is formed in a curved state, the antireflection film 14 is formed in the same manner as described above, so that the incident light reaching the pattern 12 is sufficiently attenuated by the antireflection film 14. It Therefore, the amount of light collected by the curvature of the pattern 12 does not reach the amount of light that causes halation. Even if the amount of light causing halation is reached, it is absorbed again by the antireflection film 14, so that halation does not occur in the resist film 15.

Further, as shown in FIG. 2, the pattern 12 is formed on the substrate 11 and then the pattern 1
Another antireflection film 21 is formed on the surface of 2. After that, the interlayer film 13 is formed on the upper surface of another antireflection film 21. Next, as in the case of the above-described embodiment, the antireflection film 14 is formed on the upper surface of the interlayer film 13, and then the resist film 15 is formed and the photosensitive treatment is performed. In this case, since the antireflection film 14 and another antireflection film 21 are formed, the antireflection effect is further enhanced.

[0015]

As described above, according to the present invention,
Since the antireflection film is formed on the interlayer film, the unevenness of the pattern surface does not reduce the incident light absorption performance of the antireflection film. Even if the pattern surface is curved, the incident light reaching the pattern is sufficiently attenuated, so that the amount of light collected by the curvature does not reach the amount of light causing halation. Therefore,
The resist pattern can be formed with high resolution and high accuracy without causing halation. As a result, when the interlayer film is etched using the resist pattern as an etching mask, the accuracy of the pattern formed on the interlayer film can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a halation prevention method according to an embodiment.

FIG. 2 is an explanatory diagram of another halation prevention method.

FIG. 3 is an explanatory diagram of a problem.

FIG. 4 is an explanatory diagram of another problem.

[Explanation of symbols]

 11 substrate 12 pattern 13 interlayer film 14 antireflection film 15 resist film

Claims (1)

[Claims] 1. A first step of forming an interlayer film so as to cover a pattern on a substrate, a second step of forming an antireflection film on an upper surface of the interlayer film, and an upper surface of the antireflection film. A method for preventing halation in photolithography, which comprises the step of forming a resist film on the substrate, and then subjecting the resist film to a photosensitive treatment.