JPH06349724A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form an accurate rectangular photoresist pattern with high reproducibility by forming a chemically-amplified positive photoresist film on a semiconductor substrate and exposing the entire surface of the photoresist film after once exposing the photoresist film by using a mask having a desired pattern. CONSTITUTION:A chemically-amplified positive photoresist film 2 is formed on a semiconductor substrate 1 and the film 2 is exposed to excimer laser light by using a mask 4 on which a desired element pattern is formed. As a result, an acid generating area 3 is formed in the film 2. Then the entire surface of the film 2 is exposed after removing the mask 4. The exposure is performed so that a large volume of acid generating area 3A can be formed in the film 2 at the depth from 50nm to 100nm from the surface of the film 2. Then heat treatment is performed. When the film 2 is developed in accordance with a prescribed developing sequence after heat treatment, a rectangular resist pattern 2A is obtained, because the large volume of acid generating area 3A is also dissolved easily.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device using a chemically amplified resist.

[0002]

2. Description of the Related Art In photolithography used in a conventional semiconductor device manufacturing process, the exposure light is g-line (436n).
m) and i-line (365 nm) were used, and as the resist, a dissolution-inhibiting positive resist using a novolak resin as a base resin and naphthoquinonediazide as a photosensitizer was the mainstream. However, excimer laser light (248 nm, 193 nm) that is far-ultraviolet light that is more advantageous for miniaturization
However, conventional resists for g-line and i-line absorb too much light, and a good resist pattern cannot be obtained, and the sensitivity is greatly increased. Met. However, a chemically amplified resist utilizing the sensitization reaction of an acid catalyst generated from a photoacid generator has been devised, and is becoming the mainstream as a resist for short wavelength lithography.

[0003]

However, the chemically amplified resist, particularly the chemically amplified positive resist, has a problem that the resist pattern 2B after development tends to have a T shape as shown in FIG. . This is because the acid generated by exposure disappears in the surface area of the photoresist film or is neutralized by the base in the air, and the solubilization reaction does not proceed in the subsequent heat treatment and the surface hardly soluble layer is formed. Is. When such a surface hardly soluble layer is formed, it is necessary to lengthen the development time or increase the exposure amount, but inevitably the dimension of the resist pattern becomes thin,
Both the resolution and the depth of focus for the pattern are impaired.

Further, in the developing sequence shown in FIG. 5, only a single and ordinary developing solution is used throughout the developing time. Therefore, since the surface hardly soluble layer, which is difficult to dissolve in a normal developing solution, is not completely dissolved, the resist pattern obtained after the completion of development tends to have a T-shape. Especially for the formation of a fine pattern, the deterioration of the shape, resolution, and depth of focus of the photoresist pattern due to such a surface-insoluble layer is fatal for the formation of a fine pattern. Reduces device reliability and yield.

[0005]

A method of manufacturing a semiconductor device according to a first aspect of the present invention includes a step of forming a chemically amplified positive type photoresist film on a semiconductor substrate, and the photoresist film having a desired pattern. Exposing the entire surface of the photoresist film after exposure using a mask.

In the method for manufacturing a semiconductor device of the second invention, a step of forming a chemically amplified positive type photoresist film on a semiconductor substrate and exposing the photoresist film using a mask having a desired pattern. And a step of treating the exposed photoresist film with a developer having a concentration higher than a prescribed concentration to dissolve the surface layer of the photoresist film and then developing with a developer having a prescribed concentration.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. 1A to 1C are cross-sectional views of a semiconductor chip for explaining a first embodiment of the present invention.

First, as shown in FIG. 1A, a chemically amplified positive type photoresist film 2 having a thickness of about 1 μm is formed on a semiconductor substrate 1 made of silicon or the like, and then a desired element pattern is formed. Excimer laser beam (wavelength 248 nm or 193 n
m). By this exposure, the acid generation region 3 is formed in the photoresist film 2.

Next, as shown in FIG. 1B, after removing the mask 4, the entire surface of the photoresist film 2 is exposed. For the exposure, for example, broad light of a mercury lamp having a wavelength of about 280 nm is used, and 50 to 100 from the surface of the photoresist film 2 is used.
This is performed so that a large amount of acid generation region 3A is formed at a depth of nm. Next, heat treatment is performed.

Next, as shown in FIG. 1C, when the development is performed according to the development sequence shown in FIG. 5, a large amount of the acid generating region 3A is easily dissolved, so that a rectangular resist pattern 2A is obtained.

As described above, according to the first embodiment, since the entire surface exposure is performed after the exposure using the mask, the hardly soluble layer is not formed on the surface of the photoresist film as in the conventional case. Therefore, it is possible to form an accurate resist pattern, and it is possible to improve the resolution and depth of focus of the pattern by 10% or more.

FIGS. 2A and 2B are sectional views of a semiconductor chip for explaining a second embodiment of the present invention.

First, as shown in FIG. 2A, similarly to the first embodiment, a chemically amplified positive type photoresist film 2 is formed on a semiconductor substrate 1 and then a mask 4 having a circuit pattern is used. Expose. The acid generating region 3 is formed in the exposed portion.

Next, as shown in FIG. 2 (b), the surface hardly soluble layer of the photoresist film 2 is dissolved using a developing solution having a concentration higher than a prescribed concentration at the beginning of the resolution sequence. The same resist pattern as shown in FIG. 1C can be obtained by proceeding the development with a developer having a normally used specified concentration.

FIG. 3 is a diagram showing a developing sequence in the second embodiment. At the beginning of the development sequence, the surface-insoluble layer is dissolved using a high-concentration developing solution, and then development is performed using a normal developing solution. After a desired developing time (about 60 seconds) has elapsed, pure water is added. Rinse with etc. FIG. 4 shows the change over time in the developer concentration at that time. The concentration of the high-concentration developing solution at this time is about twice the concentration of the developing solution used for the subsequent normal development, and the development time using the high-concentration developing solution is about 10 to 20% of the subsequent normal development. Time is appropriate. As described above, according to the second embodiment, since the surface-insoluble layer of the photoresist film is eliminated, the resist pattern shape is not T-shaped and a good shape can be obtained.

[0016]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the T-shape of the chemically amplified positive resist pattern which has been conventionally generated can be almost completely eliminated, and the rectangle Thus, a highly accurate resist pattern can be obtained. As a result, the resolution of the pattern and the depth of focus can be improved. Particularly, the effect is great for forming a fine pattern, and a rectangular photoresist pattern can be formed with good reproducibility. Therefore, the reliability and yield of the semiconductor device can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a semiconductor chip for explaining a first embodiment of the present invention.

FIG. 2 is a sectional view of a semiconductor chip for explaining a second embodiment of the present invention.

FIG. 3 is a diagram showing a developing sequence in a second embodiment.

FIG. 4 is a diagram showing a change over time in the developer concentration in the second embodiment.

FIG. 5 is a diagram showing a developing sequence of a conventional example.

FIG. 6 is a cross-sectional view of a semiconductor chip for explaining a conventional example.

[Explanation of symbols]

 1 semiconductor substrate 2 photoresist film 2A, 2B resist pattern 3, 3A acid generation region 4 mask

Claims (2)

[Claims] 1. A step of forming a chemically amplified positive photoresist film on a semiconductor substrate, exposing the photoresist film using a mask having a desired pattern, and then exposing the entire surface of the photoresist film. A method of manufacturing a semiconductor device, comprising: 2. A step of forming a chemically amplified positive photoresist film on a semiconductor substrate, a step of exposing the photoresist film using a mask having a desired pattern, and the exposed photoresist film. And a developing solution having a concentration higher than a prescribed concentration to dissolve the surface layer of the photoresist film, and then developing with a developing solution having a prescribed concentration.