JPH10333335A - Resist pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cost of resist pattern formation using chemical amplification type resists and to improve the instability of shape. SOLUTION: A chemical amplification type positive type resist 21 is formed on a silicon wafer 1 and a chemical amplification type negative type resist 22 is formed on the positive type resist 21. After exposure, the negative type resist 22 is developed, the surfaces of the resists are treated with an alkali component and then the positive type resist 21 is developed to form the objective resist pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method of forming a resist pattern used in a process of manufacturing a semiconductor device, and more particularly to a method of forming a resist pattern of a chemically amplified resist.

[0002]

2. Description of the Related Art The minimum size of a semiconductor integrated circuit is becoming smaller year by year. In response to miniaturization, higher NA of exposure equipment,
Shortening of the exposure wavelength, improvement of resist materials, and the like have been performed. In particular, DUV lithography using an excimer laser light source of a rare gas halide such as KrF without using a conventional high-pressure mercury lamp has attracted attention as a means for relatively easily achieving high resolution. In this DUV lithography,
A resist having high sensitivity and high resolution is desired, and a chemically amplified resist is used.

A method of forming a resist pattern using a chemically amplified positive resist will be described with reference to FIG.

A chemically amplified positive resist 2 is spin-coated on a silicon wafer 1 and soft-baked to form a resist layer (see FIG. 2A). Thereafter, exposure is performed by a KrF excimer laser through the mask 3, and pre-etching baking (PEB) is performed. The acid generated by the exposure is diffused by the PEB, and the acid acts as a catalyst to decompose the dissolving element agent and become alkali-soluble (see FIG. 2B). Then, a positive pattern is obtained by developing with an alkaline aqueous solution (see FIG. 2C).

When the above-described chemically amplified resist is used, the surface of the resist 2 is mainly contaminated by an alkaline atmosphere in an environment where the cleanliness is not sufficient after the application of the resist 2 (2a in the figure).

As described above, when the resist 2 is exposed to DUV light, an acid is generated by the acid generator in the resist 2, but in an alkali-contaminated region, the acid is neutralized by the alkali component, and a sufficient amount of the acid is removed. I can't get it.

For this reason, the acid is diffused by PEB and becomes soluble in the developer by a chemical reaction.
Even if a predetermined pattern is formed by the developer, an eaves-like defect (T-top) occurs at the upper portion.

As described above, when a chemically amplified resist is used, an acid generator in the resist is neutralized mainly by an alkali component, and when a positive resist is used, T-top is used.
In the case of a negative resist, there is a problem of remarkable shape defects such as a decrease in film thickness.

In order to prevent these, it is necessary to clean the basic atmosphere with a chemical filter or the like. However, these methods have problems such as a large initial cost in terms of equipment and facilities and a high cost for operation. Further, since it is technically difficult to completely suppress the basic atmosphere, some form instability is recognized.

On the other hand, a method for forming a pattern of an acid-generating chemically amplified resist capable of forming a good pattern shape is disclosed in Japanese Patent Laid-Open No.
-282553. This method
A single layer of the acid-generating chemically amplified resist layer is exposed to light, subjected to water treatment, and then sequentially subjected to baking and pattern development.

By performing water treatment after the exposure as described above, the acid concentration on the resist surface is reduced, and when the resist is a negative type, the occurrence of a bridge above the resist pattern is suppressed. In this method, a hardly-solubilized layer is formed on the resist surface to contribute to the rectangularity of the pattern.

[0012]

However, even in the above-mentioned method, the pattern formation is hindered in the presence of an alkaline atmosphere such as HMDS (hexamethyldisilazane) used for priming or the like near the resist surface. Requires a chemical filter to prevent or reduce This chemical filter is expensive and has the disadvantage of increasing the cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and has as its object to reduce cost increase and improve shape instability.

[0014]

SUMMARY OF THE INVENTION The present invention relates to a method of forming a resist pattern using a chemically amplified resist, comprising forming a chemically amplified positive resist on a wafer and forming a chemically amplified resist on the positive resist. A negative resist is formed, and after the exposure, the resist surface is treated with an alkali component in a state where the negative resist is developed, and then the positive resist is developed.

The thickness of the positive resist is 500 to 10
The thickness of the negative resist is preferably set to 20 to 100 nm.

According to the present invention, a pattern having a good shape can be formed by using an alkaline atmosphere, which is a weak point of the chemically amplified resist, in reverse. Also, since there is no need to worry about the atmosphere, an expensive chemical filter is not required.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. First, as shown in FIG. 1A, a chemically amplified positive type resist 21 is formed on a silicon wafer 1 by spin coating to a thickness of 500 to 1000 nm. A negative resist 22 is formed by spin coating to a thickness of 20 to 100 nm, and soft baking is performed to form a resist layer 20 composed of a chemically amplified positive resist 21 as a lower layer and a chemically amplified negative resist 22 as an upper layer. Form.

Next, as shown in FIG.
Through DUV exposure using a KrF excimer laser or the like. In the negative resist 22, the resist pattern 22a in the region irradiated with light has a high solubility in a developing solution.

Subsequently, as shown in FIG. 1C, after performing pre-etching bake (PEB), development is performed. By this development, the negative resist 22 in a region not irradiated with light is removed.

In the above process, there is no problem in patterning the resist pattern 22a into a predetermined shape even if the surface of the negative resist 22 is contaminated in an alkaline atmosphere.

Thereafter, as shown in FIG. 1D, the surface of the resist pattern 22a and the surface of the positive resist 21 not covered with the pattern 22a are treated with an alkali component such as HMDS. By this alkali treatment, the surface of the positive resist 21 and the negative resist pattern 22a are formed.
The acid is neutralized on the surface by the alkali component. As a result, the remaining negative resist pattern 22a becomes soluble in the developing solution.

Then, as shown in FIG. 1E, development is performed again to remove the negative resist pattern and the positive resist 21 in the region irradiated with the light. At this time, FIG.
In the step (d), since the hardly-soluble layer is not formed on the surface of the positive resist 21 in the region exposed to the light, a pattern having a good pattern shape is obtained.

[0023]

As described above, according to the present invention, a pattern having a good shape can be formed by utilizing an alkaline atmosphere which is a weak point of a chemically amplified resist. In addition, since there is no particular concern about the atmosphere, it is not necessary to use an expensive chemical filter, so that the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a method of forming a resist pattern according to the present invention for each process.

FIG. 2 is a cross-sectional view illustrating a method of forming a resist pattern using a chemically amplified positive resist according to steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon wafer 21 Chemical amplification positive resist 22 Chemical amplification negative resist 3 Mask

Claims (2)

[Claims] 1. A method for forming a resist pattern using a chemically amplified resist, comprising: forming a chemically amplified positive resist on a wafer; forming a chemically amplified negative resist on the positive resist; A method for forming a resist pattern, comprising: treating a resist surface with an alkali component while developing a negative resist after exposure, followed by developing a positive resist. 2. The film thickness of the positive resist is 500 to 1
000 nm, thickness of negative resist is 20-100 nm
The method according to claim 1, wherein: