JPH05315243A - Resist film and its formation method - Google Patents

Abstract

PURPOSE:To obtain a resist film which can comply flexibly with various kinds of requests such as the improvement of a drop in a resolution caused by the attenuation of a beam of light for exposure use in the resist film, the improvement of a close contact property with a substrate to be treated and the like. CONSTITUTION:For example, a spinner which is provided with a plurality of nozzles 11 inside the same cup 12 is used. Resists whose composition is different are discharged sequentially from the individual nozzles inside the same sequence. The composition of a resist film is changed sequentially.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist process used in the manufacture of semiconductor devices, and more particularly to the manufacture of a resist film and its forming method.

[0002]

2. Description of the Related Art Conventionally, in a resist process of this type, as shown in FIG. 6, for example, a photosensitive resist is ejected from a nozzle 11 onto a substrate 1 to be processed such as a silicon wafer, and spin coating is performed to form a uniform resist film. I was trying. 12 is a coater cup, 13 is a chuck for holding the substrate 1, and 14 is a rotating shaft.

The resist film thus formed becomes a desired resist pattern through exposure and development steps.

[0004]

As described above, the conventional resist film is composed of a resist having a single composition.
On the other hand, exposure is performed by irradiating light from the surface side of the resist film, but the amount of light reaching the target substrate side decreases due to the absorption of light by the resist. Therefore, for example, in the case of a positive type resist, the degree of decomposition of the photosensitizer is high on the surface of the resist film and decreases toward the contact surface with the substrate to be processed. As a result, as shown in FIG. When the film 2 was exposed through the mask 3 and then developed, the pattern profile was as shown in FIG. 3B, and high resolution could not be obtained. In particular, when a resist mixed with a substance that absorbs exposure light is used to prevent halation due to reflected light from the surface of the underlying substrate to be processed, the light absorption by the resist is significant, resulting in a decrease in resolution. It was easy.

On the other hand, in a small pattern such as a submicron pattern, adhesion after development becomes a problem, and it is an important subject to prevent peeling of the pattern as shown in FIG.

The present invention has been made in order to solve the above-mentioned problems, and prevents the deterioration of resolution due to the attenuation of the exposure light in the resist film and the improvement of the adhesion to the substrate to be processed. An object of the present invention is to provide a resist film which can flexibly meet various requirements.

[0007]

The resist film according to the present invention is one in which the composition is sequentially changed from the contact surface with the substrate to be processed toward the resist film surface.

In the method of forming a resist film according to the present invention, a plurality of types of resists having different compositions are sequentially ejected during the same sequence of spin coating.

[0009]

In the resist film according to the present invention, various properties can be given by sequentially changing the composition. For example, when a positive resist is used, the higher the concentration of the photosensitive agent in the resist or the esterification rate thereof, the higher the resistance of the unexposed portion to the developer. Therefore, according to the present invention, if the concentration of the photosensitizer in the resist film or its esterification rate is sequentially increased from the substrate side to the surface side to be treated, the solubility around the exposed portion is high near the substrate and near the surface. Since the dissolution of the portion other than the exposed portion is suppressed, the pattern profile becomes a rectangular shape with good cutting, and high resolution can be obtained.

Further, in the above example, if a resist containing a substance that absorbs exposure light is used only in the vicinity of the substrate, halation can be effectively prevented, and a low glass transition point is provided in a portion in contact with the substrate. If a resist is used, the resist in that portion is reflowed in the baking step to refill the fine irregularities on the substrate surface, and the adhesion with the substrate is improved by the anchor effect.

On the other hand, according to the forming method of the present invention,
The resist film as described above whose composition is sequentially changed is easily formed.

[0012]

【Example】

Example 1 As shown in FIG. 1, a plurality of nozzles 1 are provided in the same cup 12.
Using the spinner having No. 1, the resists having different compositions are sequentially ejected from each nozzle in the same sequence and applied on the surface of the substrate 1 to be processed. Here, a positive resist containing an alkali-soluble phenol resin and a photosensitizer is used as the resist.

In general, a resist may be mixed with a resin as a base material and a photosensitizer, or may be further esterified to improve sensitivity. In this embodiment,
From each nozzle, a resist having a different concentration of the photosensitizer or a different esterification rate thereof can be ejected.

Therefore, a resist having a low photosensitizer concentration or its esterification rate is first applied, and a resist having a high photosensitizer concentration or its esterification rate is sequentially applied.
When the resist film thus formed is exposed and developed through the mask 3 as shown in FIG. 2A, the periphery of the exposed portion is well dissolved on the substrate side and the non-exposed portion is dissolved on the other surface side. The reduction of the line width is prevented, and the pattern profile has a good rectangular shape as shown in FIG. 7B, and a high pattern resolution can be obtained.

Example 2 Using the spinner as shown in FIG. 1, first, a highly soluble resist mixed with a substance that absorbs exposure light at the time of patterning was discharged, and then the above-described Example 1 was used. Similarly, a resist having a high concentration of the photosensitive agent or a high esterification rate thereof is ejected in sequence. When the resist film thus formed is exposed by using the mask 3 as shown in FIG. 3A, the resist layer 2a containing the light absorbing substance for exposure effectively absorbs the reflected light from the substrate, Halation is prevented. On the other hand, as in the case of Example 1, since the decrease of the line width due to the dissolution of the non-exposed portion is suppressed toward the surface side of the resist film 2, a good pattern profile can be obtained as shown in FIG.

Example 3 As shown in FIG. 4A, the same resist film 2 as in Example 1 was used.
To form. Next, this is subjected to an alkali treatment to form an insolubilized layer 2b on the surface as shown in FIG. 3B, followed by exposure and further development. As a result, the reduction of the line width due to the dissolution of the surface portion is more effectively suppressed by the existence of the hardly soluble layer 2b, and a good pattern profile is obtained as shown in FIG.

Example 4 Using a spinner as shown in FIG. 1, a resist which is soluble in alkali and has a low glass transition point of about 80 to 120 ° C. is first applied, and then sequentially exposed as in Example 1. An agent or a resist having a high esterification rate is applied.
The resist film thus formed is exposed and developed as shown in FIG.

In this case, the low glass transition point layer 2c of the first layer reflows during pre-baking after resist application and baking after exposure, and the adhesion effect to the substrate 1 to be processed becomes strong due to the anchor effect. On the other hand, Example 1
Similarly, since the solubility of the non-exposed portion decreases from the substrate side toward the front surface side, a good pattern profile can be obtained as shown in FIG.

[0019]

As described above, according to the present invention, the properties of the resist film are partially or continuously changed by sequentially changing the composition of the resist film from the contact surface with the substrate to be processed toward the surface. As a result, various characteristics can be given, and it becomes possible to effectively meet various demands such as improvement in resolution and adhesion. According to the invention, by sequentially applying a plurality of types of resists having different compositions in the same sequence of spin coating,
It is possible to easily form the resist film whose composition changes as described above.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional front view showing a method for forming a resist film according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a resist film formed by the method of FIG. 1 and a resist pattern thereof.

FIG. 3 is a sectional view of a resist film and a resist pattern showing a second embodiment.

FIG. 4 is a cross-sectional view of a resist film and a resist pattern showing a third embodiment.

FIG. 5 is a sectional view of a resist film and a resist pattern showing a fourth embodiment.

FIG. 6 is a partial cross-sectional front view showing a conventional method of forming a resist film.

7 is a cross-sectional view showing an example of a resist film and a resist pattern formed by the method of FIG.

8 is a sectional view showing another example of a resist film and a resist pattern formed by the method of FIG.

[Explanation of symbols]

 1 substrate to be processed 2 resist film 11 nozzle 12 coater cup 13 chuck 14 rotating shaft

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // B05D 1/40 A 8720-4D

Claims (2)

[Claims] 1. A resist film formed on a substrate to be processed, wherein the composition in the film is sequentially changed from the contact surface with the substrate to be processed toward the surface. 2. A method of forming a resist film, comprising the step of applying a resist by spin coating on a substrate to be processed, wherein during the same sequence of spin coating,
A method of forming a resist film, which comprises sequentially discharging a plurality of types of resists having different compositions.