JPS6086545A - Mask protective film - Google Patents

Abstract

PURPOSE:To prevent a pattern formed on a mask base from being damaged at its part, especially, at its edge due to electrostatic discharge in peeling a protective film when the photomask is used, by incorporating a fine conductive power in the protective film of the photomask for use in fabrication of semiconductor integrated circuits, etc. CONSTITUTION:A pattern 12 of a thin metallic film of Cr or the like is formed on a glass base 11, and then, it is coated with a protective film 13 made of synthetic resin in order to prevent damage and pollution till it is used. A conductive fine powder of about 0.1mum particle diameter, such as iron oxide or carbon, is incorporated in said film 13. As a result, the obtained photomask can be use for semiconductor integrated circuit, etc., and its protective film is prevented from electrostatic charge. When the protective film 13 is peeled in order to use the photomask, a part of the pattern 2, especially at the edge can be prevented from being broken due to electrostatic discharge.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an improvement in a mask protective film for protecting a mask surface.

(To) Prior Art and Problems In the field of manufacturing semiconductor integrated circuits (ICs), patterns such as functional areas, electrode contact windows, and wiring are formed using photosensitive resin (regime) on the semiconductor substrate in the photo-10-senu process. ) film is irradiated with ultraviolet rays or the like using a photomask, the photomuff ')(D pattern is transferred thereto, and photoetching is performed using the pattern as a mask).

The photomask used in this photoprocessing step is usually one in which a pattern is formed with a thin film of metal such as chromium on a transparent substrate such as glass or quartz.

Additionally, during storage of photomasks until they are used, a pattern is formed as shown in Figure 1 to prevent damage to the chrome pattern formed on the transparent substrate and to prevent contamination such as dust and dirt from adhering to the photomask surface. The exposed surface is coated with a mask protective film made of a vinyl-based resin film to protect the surface, and the product is stored in a plastic bag or the like until immediately before use. In the figure, 1 is a transparent substrate made of glass or quartz, 2 is a pattern made of a thin chromium film formed on the substrate, and 3 is a mask protective film made of a vinyl resin film.

By the way, when using the photomask constructed as described above in the photoprocessing step, the mask protective film 3 on the substrate 1 must be peeled off to expose a clean mask as shown in the perspective view of FIG. Take it out and use it.

In FIG. 2, the same reference numerals as before are given.

However, when this mask protective film 3 is peeled off, a part of the chrome pattern 2 on the substrate l, especially the edge part, is damaged due to static electricity discharge at the gate between the mask protective film 3 and the transparent substrate l. There was a phenomenon.

In particular, as semiconductor devices have become increasingly highly integrated, the dimensions of patterns have become increasingly finer, and defects in some of these patterns have become a factor that lowers manufacturing yields. Even with improved accuracy, there was a problem in that the above-mentioned microscopic defects were inspected on a regular basis, resulting in a decrease in the yield of photomasks.

(C) Object of the Invention The object of the present invention is to prevent static electricity from forming on a mask protective film and prevent electrostatic damage to the pattern that occurs when the protective film is peeled off. The purpose of the present invention is to provide a mask protective film that can protect the mask.

(7) Structure of the Invention In order to achieve the object, the present invention is characterized in that a mask protective film contains conductive fine powder.

(61) Examples of the invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 8 shows a sectional view of essential parts for explaining one embodiment of the present invention.

In the same figure, for example, a metallic chromium thin film with a thickness of about 100 OA is deposited on a glass substrate 11 with a thickness of about 2.3111 mm by vacuum evaporation or sputter deposition, and the chromium thin film is coated with tetrachloride using the V cyst film as a mask. Carbon (CC!14
A desired chromium pattern 12 is formed by plasma etching using a gas such as ), and a photomask is completed.

Next, about 10% of conductive fine powder was added to the vinyl acetate resin solution.
For example, conductive fine powder of iron oxide or carbon having a particle size of about 0.1 μm is mixed and dispersed in the vinyl acetate resin solution.

A vinyl acetate resin solution in which the conductive fine powder is mixed and dispersed is dropped onto the photomask, and the vinyl acetate resin solution is spread over the photomask using an automatic machine such as a roller to a thickness of approximately 100 μm+. A conductive mask protective film 18 is coated thereon, and the film is dried at room temperature in an exhaust fume hood.

When the photomask having the above-mentioned mask protective film 18 is peeled off during use, the electrical resistance of the protective film 11k113 is lowered by the conductive fine powder contained therein, making it conductive, so that the protective film 18 does not connect to the glass substrate 11. The βJ function is to prevent the pattern 12 from being destroyed or damaged due to electrostatic discharge between the pattern 12 and the protective film 13.

Therefore, it is possible to maintain and use a photomask having a normal pattern shape without defects (m).

(0) According to the present invention, the mask protective film containing conductive fine powder prevents static electricity from being charged, thereby causing electrostatic damage to the pattern when the protective film is peeled off. It is now possible to prevent
Effective in improving quality.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part for explaining a conventional example, FIG. 2 is a perspective view showing a state in which a mask protective film is peeled off, and FIG. It is. In the figure, 11 is a glass substrate, 12 is a pattern made of a chromium thin film, and 18 is a mask protective film containing conductive fine powder.

Claims (1)

[Claims] A mask protective film characterized by containing conductive fine powder.