JPH0695355A - Mask and etching method therefor - Google Patents

Abstract

PURPOSE:To uniformalize the etching speeds of respective patterns and to improve the pattern accuracy of masks and reticules of various sizes at the time of etching the metallic light shielding films of the masks and reticules. CONSTITUTION:The resist patterns having the patterns 4 formed by dividing the patterns 2 of a large etching area among the patterns 2, 3 of different sizes by wire-shaped resist films are formed and the light shielding film deposited on a mask substrate is etched with these resist patterns as a mask at the time of forming the resist patterns on the above-mentioned light shielding film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mask (reticle) and a method for etching a metal film performed in the manufacturing process thereof.

As semiconductor devices have become highly integrated and miniaturized in recent years, high precision is also required for masks and reticles that are original plates for circuit patterns. For this purpose, a high-precision pattern drawing device and a high-precision resist are used, but a process of transferring the resist pattern to the metal light-shielding film, that is, a resist film (resist film deposited and patterned on the metal light-shielding film) High precision has also been demanded in the process of etching the metal light-shielding film using the pattern as a mask.

[0003]

2. Description of the Related Art A conventional metal film etching process involves spraying an etching solution (a liquid capable of dissolving this metal, generally a strong acid) on a resist pattern formed on the metal film.
It was applied by paddle or dipped in an etching solution to bring the liquid into uniform contact with the metal film for etching.

[0004]

However, the inventors of the present invention have found that the etching rate of metal changes depending on the etching area, and the larger the area, the slower it tends to be.

As a result, even if the etching solution is brought into uniform contact with the metal light-shielding film, the pattern sizes of the mask and the reticle are wide, so that there is an error in the pattern size of the metal light-shielding film after etching within one plate. Was occurring.

Therefore, if an attempt is made to overetch a pattern having a large etching area, the light-shielding film pattern having a small etching area becomes too large, which causes a problem.

An object of the present invention is to improve the pattern accuracy of the mask and reticle by making the etching rate of each pattern uniform when etching the metal light-shielding film of the mask and reticle having patterns of various sizes.

[0008]

Means for Solving the Problems To solve the above-mentioned problems, 1) a blank pattern obtained by dividing a pattern having a large etching area among blank patterns having different sizes of a light-shielding film deposited on a mask substrate with a linear light-shielding film. Or 2) when forming a resist pattern on a light-shielding film deposited on a mask substrate, it has a pattern obtained by dividing a pattern having a large etching area among the blank patterns of different sizes with a linear resist film Form a resist pattern,
This is achieved by an etching method of etching the light shielding film using the resist pattern as a mask.

[0009]

1 (A) and 1 (B) are explanatory views of the principle of the present invention. The figure shows a state in which a metal light-shielding film is deposited on a mask substrate and a resist pattern is formed thereon.

In the figure, reference numeral 1 denotes a region where the metal light-shielding film is left, and a region where the resist film is adhered. Reference numerals 2 and 3 denote regions where the metal light-shielding film is removed by etching. The resist is peeled off by pattern drawing and development processing. Area.

FIG. 1 (A) shows a desired pattern, and FIG. 1 (B) shows that a pattern 2 having a large etching area is divided into a division pattern 4 having substantially the same size as a pattern 3 having a small etching area. A resist pattern is formed so that the resist film remains on the boundary line.

As described above, even in a mask or reticle having patterns having different etching areas, since a large area pattern is divided to make all the patterns uniform, the etching rate becomes uniform throughout the patterns.

Further, when the large area pattern is divided, the remaining portion of the reticle film is made a pattern thinner than the resolution limit at the time of exposure, so that no actual damage occurs.

[0014]

EXAMPLE A reticle and an etching method according to an example will be described with reference to FIG. The large area pattern 2 is 2000 μm □, and the small area pattern 3 is 2 μm □. Large area pattern line width
A resist pattern divided into patterns of about the same size as the small area pattern was formed on a 0.5 μm line, and etching was performed to form a metal light-shielding film pattern.

As a result, the produced reticle had an accuracy of ± 0.09 μm in the conventional non-division method, but could be uniformly etched with an accuracy of ± 0.02 μm in the example.

An example of the etching conditions of the embodiment is shown below. Etchant: Cerium ammonium nitrate + perchloric acid aqueous solution Metal light-shielding film: Chromium film and chromium oxide film Etching method: Dipping Here, it is not always necessary to divide the etching area to the minimum pattern size, 1 μm to 10 μm
Since the difference in etching rate due to the area between □ can be ignored in the current reticle accuracy, it is sufficient to divide it into appropriate sizes according to the size in this range.

FIG. 2 is a diagram showing an example of the relationship between the etching area and the etching rate. In this example, the etchant is diammonium cerium nitrate + aqueous solution of perchloric acid Metal film: chromium. From the figure, it can be seen that the etching area increases and the etching rate decreases.

When the resist film deposited on the wafer was exposed, developed and patterned using the mask of the embodiment, the division pattern of the large pattern did not remain because the line width of the division pattern was less than the resolution. Since the desired pattern shown in FIG. 1 (A) is obtained, the existence of the mask division pattern does not hinder.

[0019]

According to the present invention, when etching the metal light-shielding film of the mask and reticle having patterns of various sizes, the etching rate of each pattern becomes uniform, and the pattern accuracy of the mask and reticle is improved.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the present invention.

FIG. 2 is a diagram showing an example of a relationship between an etching area and an etching rate.

[Explanation of symbols]

 1 Area where the metal light-shielding film is left, area where resist film is deposited 2 Large area pattern in area where resist is peeled 3 Small area pattern in area where resist is peeled 4 Divided pattern

Claims (2)

[Claims] 1. A mask having a cutout pattern obtained by dividing a pattern having a large etching area out of cutout patterns having different sizes of a light-shielding film deposited on a mask substrate by a linear light-shielding film. 2. A resist pattern having a pattern obtained by dividing a pattern having a large etching area out of blank patterns of different sizes by a linear resist film when forming a resist pattern on a light-shielding film deposited on a mask substrate. And etching the light-shielding film using the resist pattern as a mask.