JPH0366656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to improvements in pattern forming masks used in the manufacture of semiconductor devices.

[Prior art]

Figure 1 shows how a pattern forming mask used in the manufacture of conventional semiconductor devices is applied. This is formed on the glass substrate 1 to a thickness of 600 Å to 800 Å by vapor deposition or sputtering.

As a conventional pattern forming mask for a semiconductor device, a hard mask using Cr as described above is generally used. However, with wet etching of Cr, it is difficult to manufacture a high-precision mask, and with dry etching, a high-precision mask can be obtained, but the Cr etching rate is about 100 Å/
It was not suitable for mass production because the efficiency was poor when it was less than min, and the selectivity of the resist used in combination was also poor.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the above-mentioned conventional methods. Specifically, molybdenum (Mo) or tungsten (W) having a film thickness of 500 Å to 1000 Å is deposited on a glass substrate made of quartz or the like. Alternatively, a tantalum (Ta) silicide film is formed and this is used as a pattern forming mask.

By the way, pattern forming masks used in the manufacture of semiconductor devices initially used photographic emulsion dry plates with glass substrates, but as higher integration and miniaturization progress, they are now made using Cr on glass substrates. So-called hard masks, which are made of metal thin films such as these, are widely used. Such a metal thin film such as Cr is formed to a thickness of approximately 600 Å to 800 Å by vapor deposition or sputtering, and to create the required mask, photoresist or electron beam (EB) resist, etc., is applied on this metal thin film. After applying the appropriate coating, a desired pattern is drawn on it using light or EB, and then it is created through processes such as development and etching.

Note that if the metal thin film is Cr, etching is performed using ceric ammonium nitrate and perchloric acid in the wet method, or with a mixed gas of carbon tetrachloride (CCl ₄ ) and oxygen (O ₂ ) in the dry method. I will do it with
It is known that the dry etching method is advantageous especially when the semiconductor device is highly integrated and has a fine pattern, such as VLSI. This invention will be explained below.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the present invention. In this figure, 1 is a transparent glass substrate made of quartz or the like; 3 is molybdenum (Mo), tungsten (W), or tantalum ( It is a silicided film of Ta) with a thickness of about 500 Å to 1000 Å, and when forming a film with a thickness in this range, it can be formed with high accuracy, especially if performed using the ICB (Ionized Cluster Beam) method. You can get the following.

As described above, photoresist or
After applying EB resist to a thickness of about 500Å,
Draw a predetermined pattern with light or EB. Thereafter, the silicided film 3 is etched through a development process. Etching in this case can be easily performed using a dry method.

Specifically, in the case of the Mo silicide film 3, a mixed gas of CF ₄ +O ₂ (2%) is used, and the temperature is 0.2 Torr.
When etching is performed at a vacuum level of 300 W, the desired processing is completed at an etching speed of approximately 1000 Å/min. This etching speed is
The dry etching speed is approximately 1/10 compared to conventional Cr dry etching speed.

In this way, the patterned mask obtained by etching away the silicide film with a thickness of 500 Å to 1000 Å has the desired optical density as a mask, and since the film thickness is 500 Å or more, the silicide film is Since defects such as pinholes did not occur and the film thickness was less than 1000 Å, fine patterns could be formed.

The case of the Mo silicide film 3 has been explained above, but the W or Ta silicide film 3 has been explained above.
It is also possible to obtain the same effect.

In addition, the silicided film 3 of the present invention has extremely good adhesion to the glass substrate 1 compared to the conventional case.

〔Effect of the invention〕

As explained above, the present invention forms a silicided film of Mo, W, Ta, etc. with a film thickness of 500 Å to 1000 Å on a glass substrate,
Since this is used as a pattern forming mask, the desired optical density as a mask can be obtained, the etching speed is extremely fast compared to conventional Cr metal thin films, and fine patterns can be easily obtained. Since the adhesion strength to the glass substrate is also high, there is an advantage that a highly reliable product can be obtained.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the deposition state of a conventional pattern forming mask for semiconductor devices using a metal thin film;
FIG. 2 is a sectional view showing a state in which a pattern forming mask for a semiconductor device of the present invention using a silicided film is applied. In the figure, 1 is a glass substrate, 2 is a metal thin film, 3 is a silicided film, and 4 is a polysilicon film. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A mask blank for a semiconductor device, which includes a glass substrate and a mask blank material provided on the glass substrate, and the mask blank material is made of a silicided film of molybdenum, tantalum, or tungsten with a film thickness of 500 Å to 1000 Å.