JPH10208995A - Transfer mask for exposure to charged particle beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a transfer mask from causing migration together with silicon in a substrate when the mask is irradiated with an electron beam by providing a conductive thin film composed of an osmium film as the electrification preventing film of the transfer mask. SOLUTION: Firstly, a transfer mask 13 for exposure to a charged particle beam composed of a transfer pattern 6 and transfer pattern openings 11 is formed through a prescribed process. Then an osmium film 12 is formed on the mask 13 carrying no electrification preventing film by the plasma film forming method. The osmium film 12 works as an electrification preventing film and prevents the mask 13 from causing migration together with silicon in a substrate. Therefore, the conductivity of the mask 13 can be maintained and the positional deviation of a plotted pattern due to charge-up can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer mask for charged beam exposure used in a so-called batch exposure type charged beam exposure apparatus used for forming a fine pattern of a semiconductor integrated circuit or the like.

[0002]

2. Description of the Related Art Patterns of semiconductor integrated circuits tend to be miniaturized year by year and are becoming more complicated. In order to draw and form such a pattern with a charged beam exposure apparatus, a method of drawing a figure and a group of figures that are used repeatedly in a single shot, a so-called batch exposure method, a block exposure method,
Alternatively, a method called a character projection method has been proposed.

In this method, the transfer mask in the charged beam exposure apparatus is changed to a hole having a round hole in the case of the conventional point beam system, or a rectangular hole in the case of the variable shaped beam system. By making a group of figures and figures, it is possible to draw with one shot, and a dramatic improvement in throughput is expected.

By the way, the transfer mask used in this method has conventionally been structured, for example, as shown in FIG.
The gold film 32 was used as the antistatic film.

[0005]

However, in the conventional transfer mask, the gold film 32 used as the antistatic film migrates with the underlying silicon by electron beam irradiation.
There is a problem that the conductivity deteriorates and charge-up causes a displacement of a drawing pattern. In addition, damage and contamination at the time of electron beam irradiation were large, and long-time use was not possible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems. A charged beam exposure method in which an antistatic film having good conductivity is formed without causing migration with underlying silicon during electron beam irradiation. To provide a transfer mask.

[0007]

According to the present invention, there is provided a transfer mask for use in a charged beam exposure method, wherein a conductive thin film made of an osmium film is provided as an antistatic film of the transfer mask. Transfer mask.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The transfer mask for charged beam exposure according to the present invention forms an antistatic film by forming an osmium film on both sides of a transfer mask formed on a single-crystal silicon wafer and on side surfaces of a transfer pattern. The osmium film has excellent conductivity, and is less thermally damaged even when irradiated with an electron beam, and hardly causes migration with underlying silicon. The osmium film is formed by a plasma film formation method, a sputtering method, a CVD method, or the like. Here, the antistatic film may not always be required on both sides and the entire side surface depending on drawing conditions such as an acceleration voltage and a current value depending on the charged beam exposure apparatus.

By using an osmium film as an antistatic film for a transfer mask for charged beam exposure, migration does not occur with silicon as a base metal during electron beam irradiation, so that conductivity is maintained, and the displacement of a drawing pattern due to charge-up is maintained. Can be prevented. Further, since the osmium film has less damage and contamination due to electron beam irradiation, the mask can be used for a long time.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing the configuration of a transfer mask for charged beam exposure according to one embodiment of the present invention. FIG.
FIG. 3 is a sectional view showing a manufacturing process of a transfer mask for charged beam exposure according to one embodiment of the present invention.

First, a bonded silicon substrate 4 is prepared by bonding a single-crystal silicon wafer 1 and a single-crystal silicon wafer 3 having a plane orientation of (100) with a silicon oxide film 2. An oxide film was formed and patterned to form a multi-layered silicon oxide film pattern 5. (See FIG. 2 (a)).

Next, using the silicon oxide film pattern 5 as a resist, the single crystal silicon wafer 1 is etched by dry etching to a depth reaching the silicon oxide film 2, thereby forming a transfer pattern 6 and a transfer mask separation opening pattern 7. (See FIG. 2B).

Next, a protection film 8 for wet etching (nitride film or the like) is formed on both surfaces of the bonded silicon substrate 4 by CVD, and a transfer pattern opening and a transfer mask are formed on the protection film 8 on the single crystal silicon wafer 3. A resist pattern 9 for forming a separation opening was formed (FIG. 2C).
reference).

Next, using the resist pattern 9 as a resist, the protective film 8 on the single crystal silicon wafer 3 is dry-etched to form a protective film pattern 8a (FIG. 2D).
reference).

Next, using the protective film pattern 8a as a resist, the single-crystal silicon wafer 3 is back-etched to a depth of the silicon oxide film 2 with a heated alkali solution of potassium hydroxide to form a transfer pattern opening 11 and a transfer mask. The separation opening 10 was formed (see FIG. 2E).

Next, the protection film 8 and the protection film pattern 8a formed on the surface of the single crystal silicon wafer 1a are removed, and the transfer pattern opening 11 and the transfer mask separation opening 1 are removed.
0 silicon oxide film 2 and silicon oxide film pattern 5
Was removed and mechanically separated from the transfer mask separation opening pattern 7 to obtain a transfer mask for charged beam exposure without an antistatic film (see FIG. 3 (f)).

Next, an osmium film 12, which is an antistatic film, is formed on both sides and a side surface of the charged beam exposure transfer mask having no antistatic film by a plasma film forming method, and the charged beam exposure transfer mask 13 of the present invention is formed. Was obtained (FIG. 3).
(G)). The transfer mask 13 for charged beam exposure manufactured in this manner is incorporated in a mask holder 14 and mounted on an electron beam drawing apparatus (see FIG. 3H). Note that the osmium film as the antistatic film may be formed after being incorporated into the mask holder 14, and does not affect the reliability of the transfer mask.

[0018]

As described above, according to the present invention,
By using an osmium film as the antistatic film of the transfer mask for charged beam exposure, migration does not occur with the underlying metal silicon during electron beam irradiation, so that the conductivity is maintained and the displacement of the drawing pattern due to charge-up can be prevented. . Further, since the osmium film has less damage and contamination due to electron beam irradiation, the mask can be used for a long time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a transfer mask for charged beam exposure according to one embodiment of the present invention.

FIGS. 2A to 2E are cross-sectional views illustrating steps of manufacturing a transfer mask for charged beam exposure according to an embodiment of the present invention.

FIGS. 3 (f) to 3 (h) are cross-sectional views showing steps of manufacturing a transfer mask for charged beam exposure according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view showing a configuration of a conventional transfer mask for charged beam exposure.

[Explanation of symbols]

1, 3 single crystal silicon wafer 1a single crystal silicon wafer on which transfer pattern and transfer mask separation pattern are formed 2 silicon oxide film 3a transfer pattern opening and transfer mask separation opening Single crystal silicon wafer 4 Bonded silicon substrate 5 Silicon oxide film pattern 6, 26 Transfer pattern 7 Transfer mask separation opening pattern 8 Protective film (silicon nitride film) 8a Protective film pattern 9 ... Resist pattern 10 Transfer mask separation opening 11, 31 Transfer pattern opening 12 Osmium film 13, 33 Transfer mask for charged beam exposure 14 Mask holder 32 Gold film

Claims (1)

[Claims] 1. A transfer mask for use in a charged beam exposure method, wherein an antistatic film of the transfer mask is made of an osmium film.