JPH05234851A - Formation method of resist pattern - Google Patents

Abstract

PURPOSE:To form a resist pattern with high accuracy and with good line-width controllability by a method wherein a substrate on which a photoresist film has been formed is exposed, in a prescribed pattern, to a first beam of light and, after that, it is exposed, in the same pattern, to a second beam of light whose phase is displaced by 180 deg. with reference to the first beam of light and the substrate is developed. CONSTITUTION:A substrate 1a is arranged in a projection aligner; a phase conversion member plate 5 is removed from a light path; a beam of light-source light 3 is irradiated; a photoresist on the substrate 1a is exposed, in a prescribed pattern, to a first beam of light. Then, the phase conversion member plate 5 is arranged in the light path; the beam of light-source light 3 is irradiated; the photoresist on the substrate 1a is exposed in the same pattern. A second beam of light is converted into a phase displaced by 180 deg. after a beam of light whose phase is the same as that of the first beam of light has been passed through the phase conversion member plate 5. Then, the substrate is developed; a resist pattern whose edge accuracy is high and which is provided with a desired line width is formed. Thereby, the resist pattern can be formed with high accuracy and with good line-width controllability.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resist pattern. More specifically, it relates to improvement of the exposure method.

[0002]

2. Description of the Related Art Conventionally, a method of forming a resist pattern is
A method is known in which a semiconductor substrate having a photoresist film formed on its surface is placed in a projection exposure apparatus, and light of one phase is exposed in a predetermined pattern and developed.

[0003]

In the conventional method of forming a resist pattern described above, a standing wave is generated due to the interference between the incident light on the photoresist film and the reflected light reflected by the incident light reaching the substrate. And the line width controllability of the resist pattern 22 formed on the substrate 21 after development is poor as shown in FIG.

The present invention has been made to solve the above problems, and an object thereof is to provide a method of forming a resist pattern having high accuracy and good line width controllability.

[0005]

According to the present invention, the substrate on which the photoresist film is formed is exposed with the first light in a predetermined pattern, and then the phase shifted by 180 degrees with respect to the first light is exposed. There is provided a method for forming a resist pattern, which comprises forming a predetermined pattern by exposing the second light of the same to the same pattern and developing it.

In the present invention, the substrate on which the photoresist film is formed is exposed to the first light in a predetermined pattern. As the photoresist film, those used in the field of manufacturing semiconductor devices can be used, and examples thereof include an i-ray-sensitive positive photoresist film and the like.

As the first light, one having a single phase and a wavelength capable of sensitizing the photoresist film used can be used. This wavelength is usually 436-248 nm. The predetermined pattern is formed by passing the first light through the reticle. A projection exposure apparatus is usually used for the exposure.
The NA of the projection exposure apparatus is usually 0.28 to 0.54. By the exposure with the first light, as shown in FIGS. 3A and 3C, the first incident light 6 incident on the photoresist film 2a is reflected by the substrate 1 to generate the first reflected light 6a. The incident light and the reflected light interfere with each other to generate a first standing wave, as shown in FIG. 3C, which causes unevenness of the exposure amount due to the waveform in the depth direction of the photoresist film 2a.

In the present invention, thereafter, the second light having a phase shifted by 180 degrees with respect to the first light is exposed in the same pattern. The second light is formed, for example, by converting the same light as the first light into light having a phase shifted by 180 degrees by passing through the phase conversion member. The phase conversion member can be composed of, for example, a quartz plate, a quartz plate having a SiO ₂ film formed on its surface, or the like. This thickness d is given by the following equation, where λ is the exposure wavelength and n is the refractive index of the phase inversion member. d = λ / {2 · (n-1)}

In the above exposure, for example, as shown in FIG. 3B, the second incident light 7 incident on the photoresist film 2a is reflected by the substrate 1 to generate the second reflected light 7a, which is reflected by the incident light. The light and the light interfere with each other to generate a second standing wave as shown in FIG. 3D, and the second standing wave is caused by the first standing wave as shown in FIG. The unevenness of the exposure amount generated in the depth direction of the film 2a is made uniform by the phase shift of 180 degrees.

In the present invention, by developing the resist pattern, it is possible to form a resist pattern having a uniform line width at the bottom of the resist, a high accuracy, and a well controlled line width up to about 0.3 μm.

[0011]

The exposure with the second light equalizes the exposure amount in the depth direction at the end of the exposure region of the photoresist film exposed with the first light by the phase shift.

[0012]

Embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 As shown in FIG. 2, a substrate 1a on which a photoresist is formed is placed in a projection exposure apparatus (NA = 0.50), and first, a phase conversion member plate 5 (made of quartz, in the direction of an arrow 5b, Refractive index 1.45,
The thickness of 406 μm) to remove it from the optical path and
Line, wavelength 365 nm) for a predetermined time to expose the photoresist on the surface of the substrate 1a in a predetermined pattern with first light.

However, 4 is a reticle, (line width 0.30 μ
(for m), 5a is a direction in which the phase conversion member plate 5 is arranged in the optical path, 9 is a mirror, 10 is a condenser lens, 11 is a reduction projection lens, and 12 is an XY stage. Next, the method 5a for arranging the phase converting member plate 5 in the optical path is performed, and the light source light 3 is irradiated for a predetermined time to expose the photoresist on the surface of the substrate 1b with the same pattern by the second light.

The second light is light converted into a phase that is 180 degrees out of phase with the first light by passing light having the same phase as the first light through the phase conversion member plate 5. .
Next, when the substrate was treated with a developing solution, a resist pattern having a line width of 0.30 μm with high end surface accuracy was formed as shown in FIG.

Embodiment 2 FIG. 5 shows the first and second exposure lights shown in FIG. 2 separately. After the first exposure, immediately after the reticle 4 on the exposure optical path, a reflection optical system that extends the optical path by a distance of a half wavelength of the exposure light is inserted to perform the second exposure. As a result, the phases of the first exposure light and the second exposure light are reversed. In this embodiment, the reflective optical system is inserted immediately before the substrate to be exposed, but it may be at any position on the exposure optical path between the exposure light source and the substrate to be exposed.

The substrate 1a on which the photoresist is formed is placed in a projection exposure apparatus (NA = 0.50), and the light source light 3 (i
Line, wavelength 365 nm) for a predetermined time to form a predetermined pattern on the photoresist on the surface of the substrate 1a. At this time, in the first exposure, the exposure port that has passed through the reticle 4 directly passes through the reduction lens 11 and is irradiated onto the substrate 1a. On the other hand, in the second exposure, the exposure aperture that has passed through the reticle 4 has its optical path lengthened by a reflecting mirror of a reflective optical system, and then passes through the reduction lens 11 to irradiate the substrate 1a. At this time, the optical path lengths of the first exposure and the second exposure are adjusted on the substrate 1a so as to satisfy the phase inversion formula.

As a result of using the above apparatus and process, the conventional method had a limit of resolving a 0.40 μm rectangular line pattern, whereas the method of the present invention had a finer 0.30 μm. It was possible to form a resist pattern having no standing wave.

Embodiment 3 In FIG. 6, the first and second exposure ports shown in FIG. 2 are indicated by the same line. After the first exposure, the position of the substrate to be exposed is moved in the optical axis direction by a distance of a half wavelength of the exposure light to perform the second exposure. As a result, the first exposure light and the second exposure light
The phase of the exposure light on the substrate surface is opposite and is reversed.
In the present embodiment, the moving distance of the substrate to be exposed is a half wavelength of the exposure light, but this distance may be an odd multiple of the half wavelength.

The substrate 1a on which the photoresist is formed is placed in a projection exposure apparatus (NA = 0.50), and the light source light 3 (i
Line, wavelength 365 nm) for a predetermined time to form a predetermined pattern on the photoresist on the surface of the substrate 1a. At this time, the irradiation position where the second exposure reaches is shifted with respect to the irradiation position of the substrate 1a where the first exposure reaches, and the optical path difference for this displaced distance is adjusted so as to meet the above-mentioned phase inversion formula.

As a result of using the above-mentioned apparatus and process, the conventional method had a limit of resolving a 0.40 μm rectangular line pattern, whereas the method of the present invention had a finer 0.30 μm. It was possible to form a resist pattern having no standing wave.

[0022]

According to the present invention, it is possible to provide a method of forming a resist pattern with high accuracy and good line width controllability.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a resist pattern produced in an example of the present invention.

FIG. 2 is an explanatory diagram of a resist pattern forming process.

FIG. 3 is an explanatory diagram of a resist pattern forming process.

FIG. 4 is an explanatory diagram of a conventional resist pattern.

FIG. 5 is an explanatory diagram of a resist pattern forming process produced in an example of the present invention.

FIG. 6 is an explanatory diagram of a resist pattern forming process produced in an example of the present invention.

[Explanation of symbols]

 1 substrate 1a substrate on which a photoresist film is formed 2 resist pattern 2a photoresist film 3 light source 4 reticle 5 phase conversion member plate 6 first incident light 6a first reflected light 6b first standing wave 7th 2 incident light 7a 2nd reflected light 7b 2nd standing wave 8 composite wave

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Makoto Tanigawa 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (4)

[Claims] 1. A substrate on which a photoresist film is formed,
A predetermined pattern is formed by exposing the first light with a predetermined pattern, and then exposing the second light with a phase shifted by 180 degrees with respect to the first light with the same pattern and developing it. Method of forming resist pattern. 2. The method according to claim 1, wherein the second light is formed by converting the same light as the first light into light having a phase shifted by 180 degrees by passing the same light through the phase conversion member. 3. The method of claim 1, wherein the second light is formed by converting the same light as the first light into light with a phase shift of 180 degrees by passing through the reflected light layer. 4. The phase of light is shifted by 180 degrees by moving the position of the substrate on which the first light and the second light are exposed by a distance that is an odd multiple of a half wavelength of the exposure wavelength in the optical axis direction. The method of claim 1, wherein the method is formed.