Photocopying – Projection printing and copying cameras – Step and repeat
Reissue Patent
1999-04-27
2001-09-11
Pendegrass, Joan (Department: 2852)
Photocopying
Projection printing and copying cameras
Step and repeat
C355S050000, C355S055000, C355S077000
Reissue Patent
active
RE037361
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scanning type exposure apparatus and more particularly to a scanning type exposure apparatus capable of performing preferable exposure to a substrate expanded and contracted due to a previous exposure process.
2. Related Background Art
Recently, as display devices such as of personal computers, televisions, etc., liquid crystal display devices have been used widely. In such a liquid crystal display device, transparent thin film electrodes are formed on a glass plate in the photolithography in accordance with a predetermined pattern. For the photolithography, projection exposure apparatuses are used in which an original pattern formed on a mask is exposed on a photoresist layer on a glass substrate. There are various step-and-repeat type or mirror projection type exposure apparatuses.
Generally, in such projection exposure apparatuses, an original pattern is exposed on a glass substrate repeatedly one over another for many layers. As a result, the glass substrate is expanded and contracted due to those exposure processes (heat) thereby to be deformed from the initial state. In the conventional step-and-repeat type exposure apparatuses, only one projection optical system is provided, and the expansion and contraction of a glass plate are corrected (magnification correction) by changing the magnification of the projection optical system and changing the stopped position of a substrate stage at the time of each stepping operation thereby to change distances between adjacent transferred images. Also, in the mirror projection type exposure apparatuses, the magnification in the scanning direction is corrected by sequentially changing the relative position of an original plate and a photosensitive substrate with respect to a projection optical system during scanning exposure while the magnification in the direction perpendicular to the scanning direction is corrected by changing the magnification of the projection optical system.
SUMMARY OF THE INVENTION
Recently, it is needed to form liquid crystal display substrates large in size and accordingly, it is desired to enlarge an exposure region in a projection exposure apparatus. For the enlargement of the exposure region, it is considered to use an apparatus for performing scanning exposure by the use of a plurality of projection optical systems, instead of using conventional step-and-repeat exposure apparatuses and mirror projection scanning type exposure apparatuses. For example, a plurality of illumination optical systems are provided, and respective light fluxes emitted from the illumination optical systems illuminate different areas on a mask and project images of the respective different areas onto respective projection areas on a glass substrate via the respective projection optical systems. More specifically, a light flux emitted from a light source is made uniform in its light quantity via an optical system including a fly eye lens and the like, shaped by a field stop into a desired shape, and thereafter illuminate the pattern surface of the mask. A plurality of such illumination optical systems are provided and light fluxes emitted from the respective illumination optical systems illuminate different small areas (illumination areas) on the mask. The light fluxes transmitted through the mask form pattern images of the mask on respective different projection areas on the glass substrate via the respective projection optical systems. Then, by scanning the mask and glass substrate synchronously with respect to the projection optical systems, the entire surface of the pattern region on the mask is transferred to the glass substrate.
Thus, when the scanning type exposure apparatus is provided with the plurality of projection optical systems, the expansion and contraction of the substrate cannot be corrected by the above-mentioned conventional method.
Therefore, it is an object of the present invention to provide a scanning type exposure apparatus capable of correcting the expansion and contraction of a substrate preferably even though the apparatus is equipped with a plurality of projection optical systems.
For achieving the above object, according to the present invention, in a scanning type exposure apparatus having a plurality of illumination optical systems for shaping light fluxes from respective light source into a predetermined shape with respective field stops and illuminating respective areas of a pattern region on a mask with the respective light fluxes passed through the field stops and a plurality of projection optical systems disposed so as to correspond to the respective illumination optical systems, wherein respective images of the areas of the pattern region illuminated by the illumination optical systems are projected via the respective projection optical systems onto projection areas on a substrate and the entire surface of the pattern region is exposed by shifting the mask and the substrate in a predetermined direction (X-direction) at a speed ratio in accordance with the magnification of the projection optical systems, there are provided memory means for obtaining and storing a change of shape of the substrate; magnification changing means for changing the magnification of at least one of the plurality of projection optical systems in accordance with the change of shape; and imaging position changing means for changing the position of the image of the area projected by at least one projection optical system.
Also, in accordance with, among the change of shape, a change in a perpendicular direction (Y-direction) to the predetermined direction, the magnification of the at least one projection optical system, and the position of the image projected via the at least one projection optical system in the perpendicular direction are changed, and in accordance with, among the change of shape, a change in the shifting direction (X-direction), the position of the image of said at least one projection optical system in said scanning direction is changed.
Further, the exposure apparatus is provided with speed ratio changing means for changing the speed ratio of the mask to the substrate in accordance with the change of shape of the substrate.
The plurality of projection optical systems are arranged such that adjacent projection optical systems in a perpendicular direction (Y-direction) to the predetermined direction (X-direction) are displaced from each other in the predetermined direction to form a plurality of rows in the perpendicular direction.
The imaging position changing means are a plurality of plane parallel glasses with the same thickness disposed in respective optical axes of the projection optical systems and the plane parallel glasses are displaced at respectively different angles with respect to the respective optical axes in accordance with the change of shape of the substrate.
The imaging position changing means may be a plurality of plane parallel glasses with different thickness disposed in respective optical axes of the projection optical systems and the plane parallel glasses are displaced at the same angle with respect to the respective optical axes in accordance with the change of shape of the substrate.
Also, the above substrate has a plurality of alignment marks arranged in the vicinity of the projection areas along the predetermined direction (X-direction) and the scanning type exposure apparatus further are provided with mark detecting means disposed with a predetermined positional relationship with respect to the projection optical systems in a position capable of detecting at least a portion of the alignment marks so as to detect the alignment marks while the mask and the substrate are moved; and positioning means for correcting the position of the mask or the substrate with respect to the projection optical systems in accordance with the detection result of the mark detecting means.
Also, the change of shape of the substrate is obtained in accordance with positions of the alignment marks detected by the mark
Chiba Hiroshi
Miyazaki Seiji
Mori Susumu
Narabe Tsuyohsi
Naraki Tsuyoshi
Nikon Corporation
Oliff & Berridg,e PLC
Pendegrass Joan
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