JPH11354523A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the uniformity of gate dimension by providing an oxide film to flatten a substrate and form a reflection prevention film thereon. SOLUTION: A polycrystalline silicon 9 is formed by the CVD method and a liquid oxide film 12 is formed thereon to flatten the substrate, and further a nitride film 13 as a reflection prevention film is formed thereon by the CVD method. Next, a resist 11 is applied thereon. Since the uniformity of resist film is kept during mask matching and the reflection prevention film is provided, influence of stationary wave effect is not given, thereby obtaining a pattern having less variation of finishing dimension of resist. A nitride film 13, an oxide film 12 and a polycrystalline silicon 9 are dry-etched thereafter, and the nitride film 13 and oxide film 12 are removed, so that a gate pattern having less variation of dimension can be realized.

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 for improving pattern dimensional accuracy.

[0002]

2. Description of the Related Art A resist pattern formed on a semiconductor substrate is generally used as an etching mask for forming a pattern such as a gate electrode on the semiconductor substrate. A method of manufacturing a semiconductor device using a conventional resist pattern as a mask will be described below with reference to the gate forming method of FIG. 2 as an example. FIG. 2 shows a gate forming process of a conventional semiconductor device. In the cross-sectional view, (1) is a substrate, (2) is an oxide film for stress relaxation by a nitride film (3),
(3) a nitride film for selectively oxidizing the oxide film (4);
(4) is an oxide film, (5) is an oxide film for relaxing stress of the nitride film (6), (6) is a nitride film for selectively oxidizing the isolation oxide film (7), and (7) is an active region. (8) is an N-well region, (9) is a silicon oxide film serving as a gate, (10) is a gate oxide film, (1)
1) is a resist.

Next, a gate forming process of a conventional semiconductor device will be described. First, in FIG. 2 (a), a thermal oxide film (2) is formed on a P-type substrate (1), a nitride film (3) is formed thereon by a CVD method, and an N-well region (8) is formed. Mask formation is performed to form the nitride film, and the nitride film (3) is etched. Next, in FIG. 2B, a thermal oxide film (4) is formed while phosphorus is implanted and thermal diffusion is performed. Next, as shown in FIG. 3C, the nitride film (3) is removed, and the oxide film is removed by wet etching to form an N-well region. At this time, an oxide film (4) needs to be formed because a step is required for mask alignment with the next step.

Next, as shown in FIG. 1D, an oxide film (5) is formed, a nitride film (6) is formed thereon, and a mask alignment for separating an active region is performed. (6) is etched. Further, as shown in FIG. 7E, thermal oxidation is performed to form an oxide film (7), the nitride film (6) is removed, and wet etching is performed to remove the oxide film (5). Is formed.

[0005] Next, as shown in FIG.
0) is formed by thermal oxidation, and then a polycrystalline silicon film (9) is formed.
Is formed by a CVD method. Further, as shown in (g), a resist (11) is applied, and as shown in (h), the polycrystalline silicon film (9) is dry-etched and the resist is removed to form a gate.

[0006]

Since the conventional method for manufacturing a semiconductor device is formed as described above, the active region in the N-well region and the active region on the substrate have different heights.
The resist film thickness on the active region in each region is different. Therefore, the resist dimension differs between the N-well region and the region other than the well due to the standing wave effect at the time of mask alignment. There was a problem that the property became worse. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a method of manufacturing a semiconductor device capable of improving the uniformity of gate dimensions.

[0007]

According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming a pattern forming film on a semiconductor substrate; and forming an oxide film on the pattern forming film. Forming a nitride film on the oxide film, forming a resist on the nitride film, forming a resist pattern on the resist, forming the nitride film, the oxide film, and the film on which the pattern is formed. Forming a pattern of the first and second pattern formation films by etching the film.
The height from the back surface of the semiconductor substrate to the surface of the first pattern formation film is different from the height from the back surface of the semiconductor substrate to the surface of the second pattern formation film.

According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming an active region and an isolation region on a semiconductor substrate; and forming a pattern formation film on the active region and the isolation region. Forming an oxide film on the pattern formation film, forming a nitride film on the oxide film, and forming a resist on the nitride film;
Forming a resist pattern on the resist; and etching the nitride film, the oxide film, and the pattern-formed film to form a pattern of the pattern-formed film. The pattern formation film has a step due to the active region and the isolation region.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. 1 (a) to 1 (f) are cross-sectional views showing a gate forming step of the semiconductor device of the present invention. The reference numerals (1) to (11) in the figure are the same as those of the related art, and the description thereof is omitted. In the figure, (12) is a liquid oxide film applied by a coating apparatus, and (13) is a nitride film acting as an antireflection film.

Next, the manufacturing process will be described. 2 (f), in which the polycrystalline silicon (9) is formed by the CVD method, is the same as the conventional one. First, in FIG. 1 (b), the polycrystalline silicon (9) is A liquefied oxide film (12) for flattening is applied, and a nitride film (13) is formed thereon by a CVD method as an antireflection film.
Next, a resist (11) is applied thereon as shown in FIG.

Thereafter, when mask alignment is performed as shown in FIG. 1D, the uniformity of the resist film thickness is good, and since the anti-reflection film is provided, the resist is not affected by the standing wave effect. A pattern with little variation can be obtained. Thereafter, the nitride film (13), the oxide film (12) and the polycrystalline silicon (9) are dry-etched as shown in FIG. (E), and the nitride film (13) and the oxide film (12) as shown in FIG. By removing (), a gate pattern with small dimensional variation can be obtained.

In the above embodiment, the case where the nitride film (13) is provided as the antireflection film has been described. However, the same effect can be obtained with polycrystalline silicon or metal silicide such as molybdenum silicon or tungsten silicon. Further, the oxide film (12) itself for improving flatness is
As long as it functions as an anti-reflection film, the same effect can be obtained even if the anti-reflection film (13) on the oxide film is unnecessary.

[0013]

As described above, according to the present invention, the oxide film for improving the flatness is provided, and the antireflection film is formed thereon. In addition, the antireflection film does not affect the resist at the time of patterning because of the oxide film for improving the flatness. Therefore, the variation in the size of the gate resist pattern can be reduced by the standing wave effect.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a gate forming step of a semiconductor device according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a gate forming step of a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 7 Separation oxide film 8 N well region 9 Polycrystalline silicon film 10 Gate oxide film 11 Resist 12 Liquid oxide film 13 Nitride film

Claims (2)

[Claims] A step of forming a pattern formation film on a semiconductor substrate; a step of forming an oxide film on the pattern formation film; a step of forming a nitride film on the oxide film; Forming a resist thereon, forming a resist pattern on the resist, etching the nitride film, the oxide film, and the pattern formation film to form a pattern of first and second pattern formation films. Forming a height from the back surface of the semiconductor substrate to the surface of the first pattern formation film and the height from the back surface of the semiconductor substrate to the surface of the second pattern formation film. A method for manufacturing a semiconductor device, wherein the heights are different. A step of forming an active region and an isolation region on the semiconductor substrate, a step of forming a pattern formation film on the active region and the separation region, and forming an oxide film on the pattern formation film. Forming, forming a nitride film on the oxide film, forming a resist on the nitride film, forming a resist pattern on the resist, forming the nitride film, the oxide film, Forming a pattern of the pattern formation film by etching the pattern formation film, wherein the pattern formation film has a step due to the active region and the separation region. Semiconductor device manufacturing method.