JPH0661000B2 - Mask manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to improvement of a mask manufacturing method, particularly a method of forming a fine pattern on a mask dry plate by etching. In order to accurately form a film, a silicide (silicide) film is formed on the chrome film when etching the chrome film of a transparent substrate such as a quartz substrate and a chrome film and a resist film on the mask dry plate. And a resist film are sequentially formed, and the silicide film is selectively etched by using the resist pattern obtained by patterning the resist film as a mask to form a silicide pattern, the resist pattern is peeled off, and the silicide pattern is masked. To selectively etch the chrome film and then remove the silicide pattern. Including the configuration.

[Industrial application field]

The present invention relates to a method for manufacturing a mask, and more particularly to an improvement in a method for forming a fine pattern on a mask dry plate by etching.

In forming a semiconductor integrated circuit, a mask on which a predetermined pattern is formed by ion implantation or etching is used, but recently, the pattern of the integrated circuit is required to have a submicron order in order to increase the degree of integration. Miniaturization of patterns used for such pattern formation,
High integration is required.

[Conventional technology]

A conventional mask forming method will be described with reference to FIG.
As shown in the figure (a), a chromium film 12 (thickness 1000 Å) is formed on a quartz substrate 11 having a thickness of about 2.5 mm by sputtering, and the chromium film 12 (thickness: 1000 Å)
A resist having a thickness of 5000Å to 10000Å is applied to form a resist film 13. Thus, what consists of a quartz substrate, a chrome film, and a resist is called a mask dry plate. In this example, the resist uses a positive photoresist, but it may be a negative photoresist, or for electronic beer (EB). It may be a resist. Further, the chromium film 12 is formed directly on the quartz substrate, but chromium oxide (CrO
There is also an example in which x) is formed and pure chromium is sputtered on it, and further an example in which it has a three-layer structure of chromium oxide / chromium / chromium oxide.

Next, as shown in FIG. 2B, the resist film 13 is exposed according to a predetermined pattern.

Next, when the resist film 13 is developed, the exposed resist is melted to form a resist pattern 13a as shown in FIG. 2 (c).

Using this resist pattern 13a as a mask, the chromium film 12 is etched as shown in FIG. 2 (d).

Then, the resist pattern 13a is peeled off to obtain the chromium film pattern 12a shown in FIG. 2 (e). The semiconductor integrated circuit is manufactured using the mask thus created.

[Problems to be solved by the invention]

However, according to the above-mentioned conventional method, when the chromium film is etched by the dry process, the poor selection ratio between chromium and the resist poses a problem, and the etching process is determined by the selection ratio. Therefore, it is necessary to use a high etching rate. Can not.

More specifically, in the case of a positive type of EB resist, the selection ratio of chromium to resist is chromium: resist = 1: 2, which means that when one thickness of resist is etched, Means that a thickness of resist is etched. Thus, for example, when etching a chromium film having a thickness of 1000 Å, the etching cannot be performed reliably unless a resist film having a film thickness of at least 5000 Å is used.
In order to form a fine pattern, it is necessary for the resist to have a thin film thickness, but in the conventional method, as described with reference to FIG. 2, the resist must be applied to a film thickness of 5000 Å to 10000 Å. There is a problem that it is difficult to realize pattern etching.

Further, an example of using a positive photoresist and etching the chrome film with the chrome film thickness of 1 against the chrome film thickness of 5 will be described with reference to FIG. The side wall of 13a is not straight, but is developed with an inclination of 60 degrees at the bottom as shown in FIG. 3 (a). When the chromium film 12 is etched using the resist pattern 13a as a mask, the shape of the resist side wall becomes Cr.
Transferred to the film, the chrome film pattern 12a also has a 60 degree slope at the bottom, and on each sidewall for the pattern width it should be.
The pattern shifts inward by 500Å, and the total amount of this shift is 500
Å + 500Å = 1000Å (0.1 μm), and when trying to form a submicron width pattern, this 0.1 μm deviation results in a deviation of about 10% in pattern accuracy.

Therefore, an object of the present invention is to pattern a chrome film on a mask dry plate with high accuracy to form a highly reliable fine pattern with high accuracy.

[Means for solving problems]

The above-mentioned problem is that a silicide (silicide) film and a resist film are formed on the chrome film when etching the chrome film of a mask dry plate which is transparent to light, for example, a quartz substrate and a chrome film and a resist film thereon. Sequentially formed, the silicide film is selectively etched using the resist pattern obtained by patterning the resist film as a mask to form the silicide pattern, the resist pattern is peeled off, and the chromium film is selected using the silicide pattern as a mask Of the silicide pattern and then stripping the silicide pattern.

〔Example〕

Hereinafter, the present invention will be specifically described with reference to an embodiment shown in the drawings.

Referring to FIG. 1 which shows the steps of the method of the present invention in cross section, the mask dry plate is, as shown in FIG. To a thickness of 200 Å, and a silicide film (for example, molybdenum silicide film) 14 is formed to a thickness of 200 Å, and a resist film (whether positive or negative) 13 is 5,000 Å or less. To form. The chromium film may contain a chromium oxide film as described above, and the resist may be an EB resist. In addition, the film thickness of the resist is 1 μm or less in the conventional example, but it is as thin as 5000 Å or less, so that there is an advantage that the patterning of the resist film is finely and accurately performed.

Then, as shown in FIG. 1 (b), the resist film 13 is exposed and developed to form a resist pattern 13a shown in FIG. 1 (c).
To get

The silicide film 14 is etched using the resist pattern 13a as a mask. For example, the etching of the silicide film is performed by
By plasma etching using CFCl ₂ + O ₂ gas at a pressure of 200 to 400 mTorr (FIG. 1 (d)).

Then, as shown in FIG. 1 (e), the resist pattern 13a is peeled off to obtain a silicide pattern 14a.

The chrome film 12 is etched using the silicide pattern 14a as a mask as shown in FIG. 1 (f). CCl _{4 for that}
By plasma etching under a pressure of 200-400 mTorr using + O ₂ gas.

Then, the silicide pattern 14a is formed on the above-mentioned CF Cl ₂ + O ₂
When removed by etching using a gas, the chromium pattern 12a shown in FIG. 1 (g) is obtained. Thus, the silicide pattern functions as a mask material as a kind of intermediate resist.

As described above, since silicide and chromium can be selectively etched and the silicide film 14 is a thin film having a thickness of about 200Å, the etching of the chromium film 12 using the silicide pattern 14a is performed as shown in FIG. As shown in FIG. 3, the chrome film is etched straight so that the side wall of the etched portion is not inclined unlike the conventional example described with reference to FIG. 3, and the fine chrome pattern 12a is formed with high precision.

Note that silicide and chromium have selectivity in an etching gas, and chromium is not etched by a gas that etches silicide, and silicide is not etched by a gas that etches chromium. Is improved.

As the silicide, molybdenum, titanium, and tungsten silicide were used, and it was found that good results were obtained.

〔The invention's effect〕

As described above, according to the present invention, a fine mask pattern is formed with high accuracy and high reliability by using a resist film having a thickness half that of the conventional example and an extremely thin silicide that acts as an intermediate resist. It is effective for high integration of circuits and improvement of reliability.

[Brief description of drawings]

 1 (a) to (g) are sectional views of an embodiment of the present invention, FIGS. 2 (a) to (e) are sectional views of a conventional example, and FIGS. 3 (a) and 3 (b) are conventional problems. It is sectional drawing which shows a point. In the figure, 11 is a quartz substrate, 12 is a chromium film, 12a is a chromium pattern, 13 is a resist film, 13a is a resist pattern, 14 is a silicide film, and 14a is a silicide pattern.

Claims (1)

[Claims] 1. A chrome film (12) for etching a chrome film (12) of a mask dry plate consisting of a light-transparent substrate (11), a chrome film (12) and a resist film (13) thereon. A silicide film (14) and a resist film (13) are sequentially formed on the upper surface, and the silicide film (14) is selectively etched using a resist pattern (13a) obtained by patterning the resist film (13) as a mask. A mask manufacturing method, comprising: forming a silicide pattern (14a), selectively etching the chromium film (12) using the silicide pattern (14a) as a mask, and then peeling the silicide pattern (14a). Method.