Photocopying – Projection printing and copying cameras – Focus or magnification control
Reexamination Certificate
2000-11-24
2003-04-22
Adams, Russell (Department: 2851)
Photocopying
Projection printing and copying cameras
Focus or magnification control
C355S035000, C355S067000, C355S070000, C355S077000, C250S492200, C250S492220, C430S311000, C430S312000, C430S314000
Reexamination Certificate
active
06552775
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a scanning exposure apparatus provided with a plurality of optical projecting systems and a plurality of illumination systems, and also to an exposure method. In particular, this invention relates to a scanning exposure apparatus wherein the adjustment of position among the optical systems thereof can be facilitated to thereby make it suited for performing the exposure of substrate which has been deformed in the processing of the substrate, and also to an exposure method which is suited for performing the exposure of substrate which has been deformed in the processing of the substrate.
In recent years, due to the reasons that a prominent improvement in display quality has been made in the liquid crystal diaplay apparatus and that the liquid crystal display apparatus is thin in structure and light in weight, the liquid crystal display apparatus is now increasingly employed as an image display device in place of the CRT. In particular, there has been a prominent advance in enlarging the active area of direct viewing type liquid crystal panel of active matrix system, so that the size of glass substrate to be employed for manufacturing such an enlarged liquid crystal panel is also increasingly enlarged.
As for the exposure apparatus for carrying out an exposure for forming an element pattern of display panel on such a large glass substrate, there is known a scanning exposure apparatus wherein an original image pattern image formed on a photomask or reticle (hereinafter referred to simply as a mask) is projected through an optical projecting system on the surface of the glass substrate (hereinafter referred to also as a photosensitive substrate), and concurrently, the mask and photosensitive substrate are scanned relative to the optical projecting system.
One example of such an optical projecting apparatus as mentioned above will be explained with reference to
FIGS. 22 and 23
which show a scanning exposure apparatus designed to carry out an exposure treatment on a glass substrate.
FIG. 22
shows a perspective view schematically illustrating the construction of a conventional scanning exposure apparatus, and
FIG. 22
shows a main portion of the scanning exposure apparatus shown in FIG.
22
.
Referring to
FIGS. 22 and 23
, a photosensitive substrate
103
is sustained on a photosensitive substrate stage
102
constituting a bottom portion of a carriage
101
having a U-shaped cross-section, and a mask
105
is retained by a mask stage
104
which is disposed over and facing the photosensitive substrate stage
102
.
By way of exposure light irradiated from an optical illuminating system
106
, a pattern constituting a portion of region of the mask
105
retained by the mask stage
104
is illuminated, and the exposure light that has passed through the mask
105
is then allowed to pass through an optical image-forming system (or an optical projecting system)
107
, thereby enabling the pattern constituting a portion of region of the mask
105
to be transcribed to a portion of the surface region of the photosensitive substrate
103
.
In this case, the mask stage
104
bearing the mask
105
and the photosensitive substrate stage
102
sustaining the photosensitive substrate
103
are scanned relative to the optical image-forming system
107
, thereby allowing the entire pattern region of the mask
105
to be transcribed to the surface of the photosensitive substrate
103
.
The optical image-forming system
107
in this case is constituted by a plurality of optical projecting systems
107
a
to
107
d
instead of a single optical projecting system, thereby allowing a plurality of small regions of the mask
105
to be concurrently irradiated by the luminous flux irradiated from the optical illuminating system
106
. As a result, the images of these plural number of small regions are concurrently transcribed through a plurality of optical projecting systems
107
a
to
107
d
onto the surface of the photosensitive substrate
103
.
FIG. 24
shows the exposure images of the scan and step according to the aforementioned scanning exposure apparatus. Referring to
FIG. 24
, the optical image-forming system (or an optical projecting system)
107
has an exposure field as shown in
FIG. 24
, so that the optical image-forming system
107
is scanned twice (SCAN
1
and SCAN
2
) in the direction A (scanning direction) relative to the photosensitive substrate
103
, and, after finishing the scanning of SCAN
2
and being stepped in the direction B, further scanned twice (SCAN
3
and SCAN
4
) in the direction C (scanning direction), thus finishing the transcription of the entire mask pattern.
Further, the sustaining mechanism for the photosensitive substrate
103
is provided with an XY stage of long stroke which makes it possible to perform the scan and step. Whereas the retaining mechanism for the mask
105
is provided with an X stage of long stroke for scanning and with a small stroke stage for correcting the Y-direction as well as the rotational direction so as to make it possible to adjust the position thereof relative to the photosensitive substrate
103
.
In the exposure operation of the aforementioned exposure apparatus, the projected image of a pattern formed in the mask
105
is required to be accurately superimposed with the pattern layer that has been formed in advance on the photosensitive substrate
103
. Therefore, an alignment between the mask
105
and the photosensitive substrate
103
is required to be performed.
For the purpose of performing the alignment, the alignment mark formed on the mask
105
as well as the alignment mark formed on the photosensitive substrate
103
are observed by means of an alignment microscope
108
to detect any misregistration between them, and then, a correction of the positional relationship between the mask
105
and the photosensitive substrate
103
is performed. On both end portions in the direction of Y of both photosensitive substrate
103
and the mask
105
, there are a plurality of alignment marks which are formed along the direction of X, so that any one of or plurality of these alignment marks are observed by means of the alignment microscope
108
. Then, based on the result detected by this alignment microscope
108
, the position and size of the photosensitive substrate
103
relative to the mask
105
are recognized. Therefore, based on this recognition, the position of the mask
105
is adjusted, or the magnification of the optical image-forming system
107
is corrected.
FIG. 25
illustrates the operation of alignment between the mask
105
and the photosensitive substrate
103
, which will be performed using the aforementioned scanning exposure apparatus.
For example, when it is found as a result of detection by means of an alignment microscope
108
that the photosensitive substrate
103
is shifted parallel in the directions of X and Y relative to the mask
105
as shown in FIG.
25
(
a
), an actuator which is designed to shift a mask table holding the mask
105
in the direction of X as well as a pair of actuators which are designed to shift a mask table holding the mask
105
in the direction of Y are actuated so as to enable the mask
105
to be shifted parallel to a suitable degree (the correction of shift).
On the other hand, when a rotational mismatch around the Z-axis is found between the photosensitive substrate
103
and the mask
105
as shown in FIG.
25
(
b
), a pair of actuators which are designed to shift a mask table holding the mask
105
in the direction of Y are actuated to a different magnitude from each other to enable the mask
105
to rotate to a suitable degree (the correction of rotation). Furthermore, a difference in relative size is found between the photosensitive substrate
103
and the mask
105
as shown in FIG.
25
(
c
), the magnification of the optical image-forming system
107
is corrected in the direction of Y, and at the same time, the actuator for shifting the mask table in the direction of X is actuated so as to enable the mask
Katsume Tomohiro
Yanagihara Masamitsu
Brown Khaled
Nikon Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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