Photocopying – Projection printing and copying cameras – Step and repeat
Reexamination Certificate
2000-01-10
2001-05-29
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Step and repeat
C355S071000
Reexamination Certificate
active
06239861
ABSTRACT:
This application claims the benefit of Japanese Application No.8-307599, which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exposure method of and a scan type exposure apparatus for exposing a substrate coated with a photosensitive agent to a mask pattern on the occasion of manufacturing a liquid crystal display device.
2. Related Background Art
In recent years, there has been frequently used a liquid crystal display panel as a display device of a word processor, a personal computer and a portable TV set etc. The liquid crystal display panel is manufactured by executing a patterning process of a transparent thin film electrode on a glass substrate in a desired configuration by photolithography. A process based on this photolithography involves the use of an exposure apparatus for projection-exposing a photosensitive agent layer such as a photoresist etc coated over the glass substrate to a circuit pattern formed on the mask. What is mainly used as the exposure apparatus is a scan type exposure apparatus for exposing the photosensitive substrate while scanning the mask and the photosensitive substrate in synchronization with respect to the projection optical system in a present situation where the liquid crystal display panel increases in its size.
The photosensitive agent such as the photoresist etc is coated over the glass substrate by use of a photosensitive agent coating device such as a spin coater and a roll coater etc. In this case, it might happen that a layer thickness of the photosensitive agent becomes large in a peripheral portion on the substrate or at the central portion on the substrate due to a characteristic etc of the photosensitive agent coating device.
A greater exposure quantity than a normal exposure quantity is required for completely exposing the area having the large layer thickness due to non-uniformity in coating of the photosensitive agent. Therefore, a separate exposure apparatus for exposing the area having the large layer thickness of the photosensitive agent due to the non-uniformity in the coating, has hitherto been installed in addition to the exposure apparatus for the pattern exposure. Providing two types of exposure apparatuses, however, presents a large problem in terms of costs and an installation space as well.
SUMMARY OF THE INVENTION
It is a primary object of the present invention, which was contrived in view of the above problems inherent in the prior art, to provide an exposure method and an exposure apparatus that are capable of double exposing an area in which an non-uniformity in coating of a photosensitive agent occurs without using a special exposure apparatus.
According to the present invention, before or after an exposure for a pattern transfer through a first illumination system, a position in which an non-uniformity in coating of a photosensitive agent occurs is partially exposed through a second illumination system.
Namely, according to the present invention, in an exposure method of exposing a substrate coated with a photosensitive agent to light beams passing through a mask by projecting the light beams thereon through a projection optical system, the improvement comprises a step of executing double exposure by exposing an area having a large layer thickness of the photosensitive agent on the substrate through the projection optical system, and by exposing through an optical system different from the projection optical system.
Further, according to the present invention, in a scan type exposure apparatus which comprises an illumination optical system for illuminating a mask, a projection optical system for projecting light beams passing through the mask onto an exposure area on a rectangular substrate coated with a photosensitive agent, and a moving device for relatively moving the mask and the substrate in synchronization in a predetermined direction with respect to the projection optical system, the improvement comprises an exposing device for exposing an area having the large layer thickness of the photosensitive agent within the exposure area.
The exposure by the exposing device can be done when relatively moving the mask and the photosensitive substrate in synchronization with respect to the projection optical system. For this purpose, it is preferable that the projection optical system and the exposing device be disposed in a direction of the relative movement (an X-direction).
The exposing device for exposing the area having the large layer thickness of the photosensitive agent is not necessarily required to expose the substrate placed on the substrate stage. For example, a possible construction is that a carrier unit for carrying the substrate to the substrate stage is provided with the exposing device, and the substrate in the process of being carried may be exposed.
Moreover, the exposing device for exposing the area having the large layer thickness of the photosensitive agent may include a control unit for controlling an exposure quantity of the exposing device in accordance with the layer thickness of the photosensitive agent.
According to the present invention, the area in which the non-uniformity in the coating of the photosensitive agent occurs is double exposed through the first illumination system and the second illumination system, and hence the photosensitive agent on the area having the large layer thickness due to the non-uniformity in the coating, can be also surely exposed. Furthermore, the second illumination system maybe provided in combination in the projection optical system for projecting a mask pattern and a substrate carriage, and no special exposure apparatus is needed for double exposing the area in which the non-uniformity in the coating of the photosensitive agent is produced, thereby causing no problem in terms of rising costs and requiring an installation space.
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Nara Kei
Naraki Tsuyoshi
Adams Russell
Nguyen Hung Henry
Nikon Corporation
Vorys Sater Seymour and Pease LLP
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