JPS604944A - Photomask - Google Patents

Abstract

PURPOSE:To protect the mask pattern of a photomask from electrostatic breakdown by sticking a polyvinyl alcohol resin layer to a face of the photomask having the mask pattern formed thereon. CONSTITUTION:A photomask 1a has a polyvinyl alcohol resin layer as a protective layer 5 stuck to a face of the photomask 1a having a mask pattern 3 formed thereon. The layer 5 is stuck by coating a polyvinyl alcohol resin soln. with a spin coater or the like in the same manner as a resist is coated in the formation of a chromium mask pattern and by drying the coated soln. The thickness of the layer 5 is uniform, and it is preferably adjusted to about 0.5- 0.8mum. The photomask 1a can be used without stripping the layer 5 even in mask alignment and exposure stages in the manufacture of a semiconductor element because the polyvinyl alcohol resin layer is transparent and has said thickness. The protecting function of the layer 5 is maintained until exposure is finished. When the photomask 1a is used again, the layer 5 is removed by washing, and a new protective layer 5 can be stuck, so the life of the photomask is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a photomask, and particularly to a structure for protecting a mask pattern.

Background of the fbl technology As semiconductor devices become more highly integrated, the patterns of photomasks used in wafer processes become finer and more highly integrated, making it even more important to ensure their quality.

High-resolution dry plate materials have often been used as materials for forming light-shielding patterns in photomasks, but because they are silver particle patterns, they lack practical resolution and durability, and in recent years, so-called hard masks have been used. Inorganic thin film patterns, particularly chromium (Cr) patterns, have come to be employed.

(C1 Prior art and problems Figure 1 (al) is a partial side sectional view and its plan view of a conventional photomask, Figure 1 (bl is a diagram showing the state where electrostatic damage has occurred, and 1 is a photomask) 2 is a glass plate, 3 is a mask pattern, and 4 is a destroyed portion.

The photomask 1 shown in Fig. 1+8) is made by depositing a thin film of chromium (Cr) on the surface of a transparent glass plate 2 and removing unnecessary parts by etching to form a mask pattern 3. There is. The mask pattern 3 made of chromium (Cr) is composed of an image with a line width of several μm, for example, and a thickness of about 0.1 μm.

Therefore, although chromium (Cr) is mechanically strong, it is fine, so care must be taken to avoid damaging the mask pattern 3.
The photomask 1 must be handled with great care.

For this reason, in order to protect it from handling during transportation, etc., if necessary, apply a soft synthetic resin that is easy to peel off, such as Silichiku II (trade name), etc. to the surface of the photomask l. I've done something like peeling this off before.

The application of this soft synthetic resin is extremely effective in terms of protection while it is being applied, but when it is removed before use, the mask pattern 3 is damaged due to the discharge of static electricity that occurs between the adhesive surfaces, as shown in Figure 1. (There is a problem that electrostatic damage often occurs, such as the BL destruction part 4.

Considering that the discharge of static electricity is not limited to the above case, it follows that the mask pattern 3 has the disadvantage of being weak against electrostatic damage.

(di) Purpose of the Invention In view of the above-mentioned conventional drawbacks, it is an object of the present invention to provide a structure for protecting a mask pattern from electrostatic damage in a photomask.

(el) Structure of the Invention The above object is achieved by the structure of the present invention, which is a photomask in which a polyvinyl alcohol resin (PVA resin) layer is adhered to the surface on which a mask pattern is formed.

In the photomask having this configuration, no electrostatic damage was observed even when the above-mentioned coated soft synthetic resin was peeled off, which conventionally caused the most electrostatic damage.

Since the polyvinyl alcohol resin layer is transparent, by making the layer thinner, the FoI mask can be used with the layer still attached during the mask alignment and exposure process. The protection function remains valid until the end of use of the photomask.

Furthermore, since polyvinyl alcohol resin is soluble in water, when using the photomask again, the previous polyvinyl alcohol resin layer can be removed and a new polyvinyl alcohol resin layer can be applied. This also has the advantage of extending the life of the photomask.

(f) Embodiment of the Invention An embodiment of the present invention will be described below with reference to the drawings. The same reference numerals refer to the same objects throughout the design.

FIG. 2 is a side view of an embodiment of a photomask according to the present invention, in which 1a indicates a photomask, and 5 indicates a protective layer.

The photomask 1a according to the configuration of the present invention shown in FIG.
On the surface of the conventional photomask 1 on which the mask pattern 3 is formed,
A protective layer 5 made of polyvinyl alcohol 4i (NuN) is formed.

The protective layer 5, which is a polyvinyl alcohol resin layer, is applied by applying a solution of polyvinyl alcohol resin using a spin coating, for example, and then drying, in the same way as resist coating when forming a pattern for a chromium (Cr) mask. I went there to do some work. The glass plate 2 of the mask 1 has a rectangular shape that is larger than a wafer used for manufacturing semiconductor devices, but at least in the area where it overlaps with the wafer, the thickness of the protective layer 5 is uniform and approximately 0.0 mm thick. 5-0.8μm
It is.

In the photomask 1a having the above structure, since scratches must not be made on the surface of the protective layer N5, it must be handled with the same care as in the case of the conventional photomask l. Although it is necessary to apply a soft synthetic resin such as Silitect ■ (trade name), no electrostatic damage was observed even when the soft synthetic resin, which conventionally caused the most electrostatic damage, was peeled off.

Since polyvinyl alcohol resin is transparent and has the above-mentioned thickness, it can also be used for mask alignment and exposure processes in semiconductor device manufacturing with the protective layer 5 still attached to the photomask 1a. The protection i1 function remains valid until the end of use of the photomask.

Furthermore, since polyvinyl alcohol resin is soluble in water, when using the photomask 1a again, the previous protective layer 5 can be removed by washing with water and a new protective layer 5 can be applied. There is also the advantage that the life of the photomask is extended, not only when compared with the conventional case where electrostatic discharge damage occurs, but also when compared with the case where there is no electrostatic discharge damage.

(gl) Effects of the Invention As explained above, according to the configuration of the present invention, it is possible to provide a method for protecting the mask pattern of a photomask from electrostatic damage, and to improve the quality of semiconductor device manufacturing by
In addition to this, there is a technology that can extend the life of photomasks.

[Brief explanation of the drawing]

Figure 1 (δ) is a partial side sectional view of a conventional photomask and its 3i 1 side view; 1 is a partial side cross-sectional view of an embodiment of a photomask according to the present invention. In the drawing, ζ, ■, 1a are photomasks, 2 is a glass plate, 3 is a mask pattern, 4 is a destroyed portion, 5 is I″A′, and a protective layer. are shown respectively. Book 2 songs (b>

Claims (1)

[Claims] A photomask characterized by having a polyvinyl alcohol resin layer adhered to a surface on which a mask pattern is formed.