Large-area mask and exposure system having the same

Provided are a large-area mask and an exposure system having the same. The mask includes a transparent substrate, which includes a light transmission region and a light-blocking region, and a plurality of bars, which is arranged on the substrate to support the substrate. When the large-area mask is installed on the exposure system, the bars can support the mask, thus preventing downward level shifting of the mask.

This application claims the priority of Korean Patent Application No. 2002-18498, filed on Apr. 4, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a large-area mask and an exposure system having the same. More specifically, the present invention relates to a large-area mask, by which level shifting caused by a gravitational load can be prevented, and an exposure system having the same.

2. Description of the Related Art

In recent years, a flat panel display, such as a liquid crystal display (LCD), has been applied in various fields from PCs to televisions. As is well known, the LCD includes a thin film transistor (TFT) substrate, a color filter substrate, and a liquid crystal layer therebetween. Here, each component located on each substrate, for example, a TFT array, a pixel electrode, and a color filter, has been produced by a known photolithographic method.

Meanwhile, as the size of an LCD increases, the size of a substrate and the size of a mask for patterning each component located on the substrate are also increased.FIG. 1is a cross-sectional view of a typical exposure system including a large-area mask. A photolithographic process for manufacturing a conventional LCD will be described hereinafter with reference to FIG.1.

An LCD substrate10is located on a support20of the exposure system. Here, the substrate10may be a glass substrate, and a predetermined layer where a pattern will be formed (not shown) and a photoresist layer (or a layer to be cured by light: not shown) are formed thereon. A mask30is located over the substrate10, and a light source50is located over the mask30. Here, the size of photolithographic mask for TFT-LCD is already reached at the size of 1500 mm×1500 mm. Additionally, it will more increase according to the development of equipment and facilities. As illustrated inFIG. 2, such a mask30includes a transparent quartz substrate32and a light-blocking pattern35arranged to form a predetermined shape on one surface of the substrate32.

When the conventional mask30was located over the substrate10, because of the very large area of the mask30, the level of a central portion was shifted by a gravitational load. Thus, a deviated distance between the mask30and the substrate10degraded the quality of exposure process.

Thus, to prevent the level shifting of the mask30, a plurality of tensile springs40was installed at edges of the mask30. The tensile spring40was installed between the edges of the mask and a sidewall of the exposure system to enable the mask30located on the substrate10to maintain a tense state.

However, as the tensile spring40itself is very expensive, installation of the plurality of tensile springs40between the mask and the exposure system caused the very high process cost. As a result, the unit production cost of the LCD was increased.

SUMMARY OF THE INVENTION

The present invention provides a large-area mask, by which level shifting of a central portion of the mask can be prevented.

The present invention also provides the large-area mask, which can maintain a tense state on a substrate even without installing a plurality of tensile springs at the edges thereof, and an exposure system having the same.

The present invention yet provides an exposure system having the foregoing large-area mask.

In accordance with an aspect of the present invention, there is provided a mask, comprising a transparent substrate, which includes a light transmission region and a light-blocking region, and a plurality of bars arranged on the substrate to support the substrate.

It is preferred in the present invention that the bar is formed of one of a transparent material, quartz, glass, and a material that transmits ultraviolet rays.

It is preferred in the present invention that an adhesive is intervened between the bar and the light-blocking region.

It is preferred in the present invention that the bar is formed of an opaque material, and a layer having high reflexibility covers both sidewalls thereof. Here, the bar may be formed of one of aluminum and a stainless material.

It is preferred in the present invention that when a plane of the transparent substrate is rectangular, the bars are arranged to be parallel in a direction of a major axis of the transparent substrate, are arranged to be parallel in a direction of a minor axis thereof, or are arranged to be parallel in a diagonal direction thereof.

In accordance with another aspect of the present invention, there is provided an exposure system, comprising a support for supporting a substrate that will undergo a lithographic process or a light curing process, a mask which is located over the support and includes a light blocking pattern, and a light source which is located on the mask. In the exposure system, a plurality of bars is located on the mask surface facing the substrate to support the mask.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough and complete and fully conveys the concept of the invention to those skilled in the art. In the drawings, the shape of the elements is exaggerated for clarity, and the same reference numerals in different drawings represent the same elements.

As illustrated inFIG. 3, an exposure system100includes a support150for supporting a display substrate110, under which a predetermined pattern will be formed. Here, the display substrate110may be a transparent glass substrate, on which a layer where a pattern will be formed120and a photoresist layer130are sequentially formed. Also, the display substrate110may be one of a TFT substrate including a light-cured layer as a seals, a color filter substrate and a display panel including the TFT substrate and the color filter substrate.

A mask200of the present invention is located over and spaced apart from the display substrate110by a predetermined distance, and a light source300is located over and spaced apart from the mask200.

As illustrated inFIGS. 3 and 4, the mask200includes a transparent substrate210, such as a substrate formed of a material that can transmit ultraviolet rays or a quartz substrate, and a light-blocking pattern220located on the surface of the transparent substrate210as a predetermined shape. Here, the light-blocking pattern220may be formed of one of chrome (Cr) and an opaque resin. A plurality of stripe-shaped bars230is located on a surface of the light-blocking pattern220and the transparent substrate210in order to prevent its level of central portion from shifting due to the gravitational load. The bars230may be installed at the lower surface of the mask200as shown inFIG. 3or the upper surface of the mask200as shown in FIG.9. Here, if the transparent substrate210has a rectangular shape, the bars230may be arranged to run across the transparent substrate210, i.e., to be parallel in a direction of a minor axis of the transparent substrate210, and be spaced apart from each other by a predetermined interval. Here, the width of the bar230depends on the size of the mask200(or the transparent substrate). In the present embodiment, the bar230is formed to have a line width of 1 to 30 mm. Also, the height of the bar230depends on the size of the mask200, and it is preferred in the present embodiment that the bar230is formed to have a height of 5 to 30 mm. The bars230may be formed at regular intervals. Alternatively, considering light transmissivity, the arrangement of the bars230may be adjusted in accordance with the arrangement of the light-blocking pattern220. The bar230can be formed of one of a light transmission material and a material that can transmit ultraviolet rays, for example, quartz or glass. Accordingly, although the bars230are formed on the transparent substrate210, there is no problem as an exposing error when the exposure processing is proceeded.

Here, as illustrated inFIG. 5, an adhesive layer240may be intervened between the bar230and the light blocking pattern220.

As mentioned above, the plurality of bars230is installed to run across the mask200, thereby supporting the mask200. This can prevent level shifting of the mask200. Further, because only a small number of bars230shows results, to install the bars on a transparent substrate is more advantageous than tensile springs in aspect of costs.

A lithographic process (or a light curing process) using the exposure system according to the foregoing embodiment will be described now.

When the light source300irradiates light, the light is partially absorbed in the mask200and partially penetrates through the mask200. That is, the light is blocked at a portion where the light-blocking pattern220is located and penetrates through a portion where only the transparent substrate210is located. After penetrating through the mask200, the light reaches the photoresist layer130(or the light-cured layer) formed on the substrate110. Thus, the photoresist layer130(or the light-cured layer) is exposed to light. Next, the exposed photoresist layer130(or the light-cured layer) is developed to form a photoresist pattern (or a light-cured pattern, not shown). Thereafter, the layer where a pattern will be formed120is etched away as a shape of the photoresist pattern (or when the light-cured layer is used, a light curing process is performed) to complete a predetermined pattern. Here, as the plurality of bars230is extended on the surface of the large-area mask200which faces the display substrate110, level shifting of a portion of the mask200is prevented.

The same reference numerals in the first embodiment and the present embodiment represent the same elements. Also, the same description in the first and second embodiments will be omitted here.

Referring toFIG. 6, a bar250of the present embodiment is formed of an opaque material such as aluminum and a stainless material. A high reflectivity layer252covers the sides of the bar250to reflect incident light toward the quartz substrate210. Here, an adhesive layer240is located at the bottom of the bar250. In the present embodiment, since the bar250is formed of the opaque material, the adhesive layer240may be formed between the bar250and the quartz substrate210or light-blocking pattern220. The bar250of the present embodiment may be placed so as to form the same plane structure as in the foregoing first embodiment, and the width, the height, and the interval of the bar250are the same as that in the first embodiment.

According to the present embodiment, even if the bar250is formed of the opaque material, the bar250can effectively support the large-area mask200. Also, because the highly reflected layer252covers the sides of the bar250, the light damaged by the opaque bar250can be restored. Here,FIG. 10is a cross-sectional view of an exposure system including the large-area mask of the FIG.6.

FIG. 7is a top plan view of a large-area mask according to a third embodiment of the present invention.

Referring toFIG. 7, when a mask200(a transparent substrate) has a rectangular shape, a plurality of bars260of the present embodiment is extended to intersect the mask200, i.e., to be parallel in a direction of a major-axis of the mask200. Here, the line width and the height of the bar260may be the same as in the first embodiment, and the bars260may be formed at regular intervals. Also, the bar260of the present embodiment may be formed of a transparent material as in the first embodiment, or formed of an opaque material with a highly reflected layer formed on the sidewalls thereof as in the second embodiment. Also, the mask200is the same as those in the foregoing first and second embodiments.

In the present embodiment, the plurality of bars260is located in the direction of the major-axis of the mask, thus obtaining the same effect as in the first and second embodiments.

Referring toFIG. 8, a bar270of the present embodiment is extended in a diagonal direction of the mask200. Here, a plurality of stripe-shaped bars270is arranged to be parallel. The line width and the height of the bar270may be the same as that in the first embodiment. The bars270may be formed at regular intervals, or the arrangement of the bars270may be adjusted in accordance with the arrangement of the light-blocking pattern220. Further, the bar270of the present embodiment is formed of a transparent material as the first embodiment, or formed of an opaque material with a highly reflected layer formed on the sidewalls thereof as the second embodiment. Also, the mask200is the same as those in the first and second embodiments.

In the present embodiment, the plurality of bars270is located in the diagonal direction of the mask200, thus obtaining the same effect as in the above embodiments.

As described above, according to the present invention, a plurality of stripe-shaped bars is arranged to be parallel on one surface of a large-area mask (the surface facing a substrate) such that when the mask is located on the substrate, the bars can support the substrate, thus preventing level shifting of the mask toward the substrate. Accordingly, level shifting of the mask can be prevented without additional tensile springs installed at the edges of the mask, thereby reducing production costs.