JPH04254856A - Dust-proof body for liquid crystal manufacturing mask - Google Patents

Abstract

PURPOSE:To obtain a dust-proof body for preventing adherence of foreign matter on a transparent base board such as photomask, etc., used in liquid crystal lithography process. CONSTITUTION:An optical thin film body 3 is provided over a supporting frame 2. The supporting frame 2 is made of tool steel or martensite system stainless steel and satisfies the conditions under which a dust-proof body for large liquid crystal manufacturing mask can be produced. Thus the dust-proof body free from deformation, etc., can be produced and the conditions necessary for the dust-proof body can be satisfied.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dustproof body used for the purpose of preventing foreign matter from adhering to a transparent substrate (hereinafter referred to as a mask) such as a photomask used in a lithography process for liquid crystals. More specifically, the present invention relates to the material of the support frame that supports the dustproof body.

0002

BACKGROUND OF THE INVENTION In order to improve the operating rate and yield of semiconductor lithography processes, a method has been adopted in which a dustproof body having an optical thin film is attached to protect a mask from foreign substances (for example, Japanese Patent Publication No. 54-28716 reference). This is due to the following circumstances. That is, in recent years, with the development of large-scale integrated circuits, the line width has become extremely fine, and the quality of the mask has greatly influenced the operating rate and manufacturing cost of semiconductor manufacturing equipment. In particular, it is an important problem that foreign matter adhering to the mask reduces the yield. Therefore, it has come to be recognized that it is useful to attach a dustproof body to a mask to protect it from foreign substances.

[0003] The above situation also applies to liquid crystals, the production of which has been increasing in recent years. As long as the lithography process, which is fundamentally different from the semiconductor manufacturing process, is involved, it is important to protect masks for liquid crystal manufacturing from foreign objects. There is a remarkable tendency for liquid crystals to become larger. In this case, the lithography work becomes very large. Conventionally, a method has been used in which one workpiece is completed by repeating exposure in small parts. However, this method has a low throughput, which poses a problem in terms of mass production. Recently, an exposure device for liquid crystals has been put on the market that can expose a larger area and, depending on the size, can also perform batch exposure.

The major difference between dustproof bodies for semiconductor manufacturing and dustproof bodies for liquid crystal manufacturing is the required size. For example, while the former is a rectangle with a maximum long side length of about 120 mm, the latter can be as long as about 440 mm. At present, there is no dustproof body of such a size, and even if a batch exposure type exposure apparatus were put on the market, the expected results would not be obtained due to the quality of the mask.

[0005] Currently, duralumin-based aluminum is mostly used as a material for support frames of dustproof bodies for semiconductor manufacturing. Furthermore, cellulose-based polymers are mainly used as optical thin films with good light transmittance that constitute dustproof bodies. Among these materials, a particularly important specification is that they have high tensile strength. As a dustproof body,
It is required that it is stretched tautly on the support frame without any slack. In the case of conventionally used aluminum dustproof bodies, it has been observed that when the optical thin film body becomes large, the support frame bends due to the tension. This point is an important problem when creating a dustproof body.

[0006]

[Problems to be Solved by the Invention] In order to provide a dustproof body for liquid crystal manufacturing, a physically strong optical thin film body with a large area is stretched so that the thin film body itself does not bend and the thin film body does not warp. First, it is necessary to provide a material for the support frame that will allow it to be stretched evenly. The physical strength of the optical thin film body is better when the film is thicker, but this increases the problem of deflection. Furthermore, it is desirable to use a material that can be processed relatively easily so that the flatness of the support frame itself of the dustproof body for liquid crystal manufacturing falls within a certain limit. Further, in order to prevent light from being reflected from the frame, as in the case of dustproof bodies for semiconductor manufacturing, it is necessary that at least the inner surface can be processed to have a black surface.

[0007]

[Means for Solving the Problems] The present invention provides the following dustproof body for manufacturing liquid crystals. A dust-proofing body for a mask for liquid crystal production, comprising an optical thin film having a thickness preferably in the range of 0.5 μm to 10 μm stretched over a support frame, and the material of the support frame is tool steel or This is a dustproof body for a mask for liquid crystal manufacturing, which is made of martensitic stainless steel and has a part or all black surface.

At first glance, it seems that there are many materials that satisfy the above conditions. Examples include common stainless steel, ceramics, resins, especially engineering plastics. However, common stainless steel is extremely difficult to machine. A sturdy jig must be made to polish the frame to make it flat, and extreme care must be taken. If you painstakingly create an optical thin film and then cover it with an optical thin film, sagging will occur.

Ceramics give the expected results, but
It is very expensive and has low practicality, including the fact that it is easily broken. On the other hand, plastic is also disadvantageous in terms of sagging. Tool steel or martensitic stainless steel also gave good results. Since these have magnetism, they can be held and processed with a magnet, so even large ones can be easily made flat. Also, chrome plating could be applied to uniformly blacken the surface. It is also cheaper and more practical.

[0010] Tool steels include the following. Examples include carbon tool steel SK series, high speed tool steel SKH series, alloy tool steel SKS series, SKD series, SKT series, etc. Martensitic stainless steels include: SUS403, SUS
410, SUS410S, SUS420J1, SUS4
20J2, SUS429J1, and SUS440A. All of these can meet the requirements for a support frame for a large dustproof body.

An additional element is the improvement in the handling of such large dustproof bodies. For this purpose, it is desirable to provide a groove on the side surface of the support frame. By providing the groove, if a jig that can be inserted into the groove is prepared separately, it can be easily handled by holding the jig after insertion. This combination of grooves and jigs is also effective when attaching a dustproof body to a mask for liquid crystal manufacturing.

Furthermore, in order to prevent unwanted reflections during exposure, it is necessary to make at least the inside of the support frame black. If the material of the present invention is used, such conditions can be easily satisfied by black chrome plating. It is also possible to leave only the surface on which the optical thin film is stretched unplated. Furthermore, although adhesive is used for this tensioning, it is possible to take measures to prevent the adhesive from seeping out.

The basic structure of the dustproof body for a liquid crystal production mask consists of an adhesive layer for attachment to a mask according to the present invention whose dimensions are adjusted. As the optical thin film body, a single layer body or a body having an antireflection layer can be used. Inorganic materials such as quartz and polymers can be used as the material for the film constituting the central layer. As the polymer, materials with high transmittance when formed into a thin film can be selected, such as polyethylene terephthalate, cellulose esters, polycarbonate, polyvinyl butyral, and polymethyl methacrylate. Particularly common materials used are nitrocellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, or mixtures thereof. As the material for the antireflection layer, inorganic materials such as MgF2 and polymers such as polystyrene and Teflon can be used. The support frame has an adhesive layer on one end surface. The adhesive strength of this layer is particularly important for the present invention;
It is preferable that it is 5 mm or more (JIS Z0237
(test method according to).

The present invention will be explained in more detail with reference to Examples below.

[0015]

【Example】

[0016]

Example 1 A rectangular tool steel SK4 measuring 500 x 2,000 mm with a thickness of 5 mm was first cut, fixed with a magnet, and the outside and then the inside were cut. Next, the grooved upper and lower surfaces were polished and then blasted. Black chrome plating was applied and the top and bottom surfaces were repolished. Double-sided adhesive tape was attached to the bottom of the completed support frame. An optical thin film body made of nitrocellulose and having a thickness of 7 μm, which had been prepared in advance, was stretched on a support frame using an ultraviolet curing adhesive. It became taut. At this time, there was no deflection of the support frame. These operations were carried out by inserting a jig into the side groove of the support frame, so the dustproof body could be made without any inconvenience.

[0017]

[Example 2] Martensitic stainless steel SU
A support frame was created in the same manner as in Example 1 except that S403 was replaced with tool steel. Like Example 1, this also had no deflection and satisfied the conditions required for a large dustproof body.

[0018]

[Effects of the Invention] As explained above, the support frame made of the material of the present invention satisfies the requirements for creating a dustproof body for large LCD manufacturing masks, that is, creates a dustproof body that does not cause deflection, etc. can satisfy the following conditions.

[Brief explanation of the drawing]

FIG. 1 is an overview diagram showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line A-A in FIG. 1.

[Explanation of symbols]

1 Mask pellicle 2 Frame 3 Pellicle membrane (e.g. nitrified cotton)

Claims (1)

[Claims] 1. A dustproof body for a mask for liquid crystal production, which comprises an optical thin film stretched over a support frame, characterized in that the material of the support frame is tool steel or martensitic stainless steel. Dust-proof body for LCD masks.