JPS5929421A - Manufacture of mask - Google Patents

Abstract

PURPOSE:To easily form with a high accuracy a mask for ion beam lithography which is free from multiple scattering and high in resolution, by forming a predetermined pattern of a metal on a silicon single crystal thin film grown on a sapphire substrate, and then selectively removing the part of the substrate corresponding to the pattern part. CONSTITUTION:An Si single crystal thin film 5 with a thickness of 0.5mum is grown on the surface of a sapphire substrate 4. Then, a predetermined pattern 6 is formed of an Au evaporated film by the lift-off or dry etching technique. Finally, a part of the sapphire substrate 4, that is, the part thereof corresponding to the pattern 6 part is selectively etched by the use of hot phosphoric acid. Since this etching solution does not dissolve Si, the Si thin film 5 is left without being etched, and the sapphire substrate 4 is left on the periphery of the pattern 6 part to serve as a frame member. If an ion beam lithography is effected using this mask, since incident ions pass through the Si by means of channeling, there will be no scattering, and the resolution will improve. According to this manufacturing method, the Si thin film 5 as an ion-transmitting part is formed by the epitaxial growth, therefore, the thin film can be formed with a high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a mask, particularly to a method of manufacturing a mask for ion beam exposure.

Conventional Structures and Problems With the miniaturization of semiconductor devices, the miniaturization of phosphorography technology is progressing. Among them, ion beam exposure is
It is attracting attention as phosphorography for microfabrication because it does not cause scattering like electron beams do, and unlike X-rays, it has a collimated image source. However, in ion beam exposure using a mask, the method of manufacturing the mask and its accuracy pose problems. FIG. 1 shows an example of a mask. Normally, the mask is manufactured by forming an SiO2 film 2 on a Si substrate 1, forming a predetermined pattern 3 using, for example, a human U thin film, and then etching the Si substrate 1 from the back side. When performing ion beam exposure using such a mask, SiO
2 Multiple scattering in the film 2
resolution (tering). Furthermore, in order to minimize the effect of multiple scattering, it is necessary to make the 5iOz film 2 thinner and to reduce the distance between the mask and the wafer, but there are optical limits. In order to prevent multiple scattering, it is possible to use a Si single crystal thin film instead of the 5102 film 2, but it is difficult to form a thin Si single crystal by etching.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned problems and aims to provide a method of manufacturing a mask without multiple scattering.

Structure of the Invention The present invention involves growing a heterocrystalline thin film on a substrate made of a predetermined material,
This method of manufacturing a mask includes a step of forming a predetermined pattern of metal on the thin film and then selectively removing the substrate in the pattern area.

DESCRIPTION OF EMBODIMENTS FIG. 2 shows an embodiment of the present invention. A Si single crystal thin film 5 with a thickness of 0.5 μm is grown on a sapphire substrate 4. Next, a predetermined figure 6 is formed using the U deposited film by lift-off or dry etching (FIG. 2(a)). Finally, a part of the sapphire substrate 4, that is, the part of the graphic 6 is selectively etched using hot phosphoric acid (second etching).
Figure Φ)). Since this etching solution does not dissolve Si, the Si thin film 5 remains without being etched. The sapphire substrate 4 left around the periphery becomes a frame.

When ion beam exposure is performed using this mask, the incident ions pass through the mask by channeling, so there is no scattering and the resolution is good. If the crystallinity of the Si thin film 6 is poor near the interface between the Si thin film 5 and the sapphire substrate 4 and ions are scattered, the sapphire substrate 4 is removed by etching, and then the Si thin film 5 is etched by Q.1 to α2 μm. do,
The portions with poor crystallinity may be removed. If this manufacturing method is used, the Si thin film 5, which becomes the ion permeation part, can be formed with high precision since it is formed by epitaxial growth, and the Si thin film 5 can be formed with high selectivity so that the Si thin film 5 is not etched when the sapphire substrate 4 is etched. By using the etching solution, the Si thin film 5 remains as it is.

In the above embodiment, a case is described in which sapphire is used as the substrate and Si is used as the single crystal thin film, but it is also possible to use different materials for both the substrate and the single crystal thin film. For example, a combination of GaAs as the substrate and pith as the single crystal thin film is possible. Furthermore, GaA as a substrate
It is also possible to use a combination of a binary compound and a ternary compound, such as using CR&S or IneaAs as a single crystal thin film.

As a material for forming a predetermined pattern on a thin film, any material with a high ion-stopping ability may be used (in addition to Au, Pt, Ag
Heavy metals such as can be used.

Effects of the Invention As described above, the present invention includes a step of growing a heterocrystalline thin film on a substrate of a predetermined material, forming a predetermined shape with metal on the thin film, and then selectively removing the substrate in the shape portion. According to the present invention, a high-resolution ion beam exposure mask without multiple scattering can be easily manufactured with high precision.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a conventional mask, Figure 2 (IL)
, (b) are process cross-sectional views showing a method of manufacturing a mask according to the present invention. 4... Sapphire substrate, 5... Si single crystal, 6... Mu U pattern. Name of agent: Patent attorney Toshio Nakao and 1 other person10
C Figure 1 Figure 2

Claims (1)

[Claims] (1) A method for manufacturing a mask, which comprises growing a heterocrystalline thin film on a substrate made of a predetermined material, forming a predetermined pattern with metal on the thin film, and then selectively removing a central portion of the substrate. 2. The method of manufacturing a mask according to claim 1, wherein the substrate is a zaphire substrate and the thin film is a silicon single crystal film.