Photocopying – Projection printing and copying cameras – Detailed holder for photosensitive paper
Reexamination Certificate
2000-08-09
2003-05-06
Nguyen, Henry Hung (Department: 2851)
Photocopying
Projection printing and copying cameras
Detailed holder for photosensitive paper
C355S053000, C355S077000
Reexamination Certificate
active
06559928
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a substrate supporting apparatus, a substrate transfer apparatus and the transfer method, a method of holding the substrate, an exposure apparatus and a method of manufacturing the apparatus. More particularly, the present invention relates to a substrate supporting apparatus suitable for supporting a thin substrate to be used in the manufacturing of liquid crystal display devices or the like and the inspection process thereof, a substrate transfer apparatus for transferring the substrate integrally with the substrate supporting apparatus and the method therefor, a method for holding the substrate on a substrate holder, an exposure apparatus comprising the substrate transfer apparatus, and the method of manufacturing the exposure apparatus.
2. Description of the Related Art
Conventionally, in the process of manufacturing, for example, a liquid crystal display device (generally called a flat panel display device), a variety of apparatus for processing a large-sized substrate such as exposure apparatus or inspection apparatus have been used. In the exposure and inspection processes using these processing apparatus, a substrate exchanging apparatus (substrate exchanging system) which automatically sets a large-sized substrate (a glass plate) onto the processing apparatus and then removes it from the processing apparatus have been employed.
FIG.11
is a schematic view of the configuration of a substrate exchanging system employed in an exposure apparatus for liquid crystal display substrates, as an example. In the exchanging system shown in
FIG. 11
, a substrate P (hereinafter also referred to as plate P) is mounted onto a substrate holder
143
in the following method:
{circumflex over (1)} The substrate P is held from underneath by a robot arm
142
and the substrate P is transferred above the substrate holder
143
.
{circumflex over (2)} In this state, a plurality of supporting bars
144
which are arranged on the substrate holder
143
for loading and unloading a substrate, are arranged via openings on the upper surface of the substrate holder
143
. The support bars
144
rise above the upper surface of the substrate holder
143
to hold up the substrate P from underneath (or the robot arm
142
may be lowered to mount the substrate P on the support bars
144
that are already positioned above the upper surface of the substrate holder
143
). In such cases, the support bars
144
are arranged to support the substrate P in and around the center, to prevent the substrate P from bending significantly.
{circumflex over (3)} When the support bars
144
rise a predetermined amount, the substrate P is lifted a predetermined amount from above the upper surface of the robot arm
142
by the support bars
144
. The robot arm
142
then is withdrawn from underneath the substrate P so as not to contact any of the substrate P, the support bars
144
, and substrate holder
143
.
FIG.12
shows the robot arm
142
, which has completed the withdrawal from the substrate holder
143
.
{circumflex over (4)} The support bars
144
are then lowered, with the substrate P being supported from underneath. The support bars
144
are lowered beneath the upper surface of the substrate holder
143
, and only the substrate P is in contact with the substrate holder
143
, being mounted on the upper surface. The substrate P is fixed onto the substrate holder
143
by suction through a number of suction holes (not shown) provided on the upper surface of the substrate holder
143
. The suction of the substrate P performed evenly, so as to improve the smoothness (flatness) of the substrate P. The substrate holder
143
moves with the substrate P, and thus exposure for liquid crystal display substrates is performed.
The removal of the substrate P from the substrate holder
143
is performed by the reversed procedures of {circumflex over (1)}-{circumflex over (4)}.
The substrate used for manufacturing flat panel display devices is a thin glass substrate, for example, 500 mm×600 mm with a thickness of 0.7 mm. This substrate can be easily damaged, even by a significant flexure. In the conventional substrate exchanging system as described above, to load the thin substrate without any damage, it has been necessary to exchange the substrate with the lower surface being evenly supported by a plurality of supporting bars. The supporting bars were arranged in and around the center of the substrate, where they did not come into direct contact with the transfer arm.
To ensure the stability of supporting the substrate, the number of supporting bars needed to be increased. This required more holes on the substrate holder in accordance with the number of the support bars, which results in depriving the substrate holder of maintaining the flatness required to support the substrate in close contact. The supporting bars, therefore, cannot be excessively increased. An increase in the number of the supporting bars also has caused the vertical movement mechanism of the supporting bars to become complicated and large-sized, which deteriorates the position controllability of the substrate holder.
The number of supporting bars had to be limited for the reasons described above, thus creating a flexure to some extent on the substrate. The flexure has kept the overall substrate from being in total contact with, and being removed from the substrate holder simultaneously, resulting in an unfavorable phenomenon that the upper surface of the substrate holder partially wears away.
In the conventional substrate exchanging system, the robot arm had a comb-shaped cantilever structure, the comb teeth facing the movement direction, arranged so as not to interfere with the supporting bars (refer to FIG.
12
), the substrate being supported in and around the center to prevent damage. The supporting bars had to lift the substrate high enough to allow the robot arm to be inserted in between the substrate and the holder. With exposure apparatus for liquid crystal display substrates, however, the space between the projection optical system (reference symbol PL in
FIGS. 11 and 12
) and the substrate holder (generally referred to as a working distance) has become smaller as the numerical aperture of the projection optical system increased. Thus, ensuring a working distance large enough for the robot arm to be inserted has become difficult. Some exposure apparatus for liquid crystal display substrates, therefore, are obliged to perform loading and unloading after the substrate holder has been moved apart from the projection optical system. This requires a larger movement stroke for the substrate holder, increasing the time for loading and unloading the substrate, and also increasing the size of foot print (the area covered by the exposure apparatus installed).
Glass substrates are yet becoming larger and larger, and in the near future, are said to become as large as 1 m×1 m. Larger substrates would obviously be a disadvantage with the conventional substrate exchanging system that has the problems described above still to be solved. Accordingly, it is an urgent task to develop a new technique to comply with the enlargement of such substrates.
SUMMARY OF THE INVENTION
The present invention was developed in view of such circumstances. A first object of the present invention is to provide a substrate supporting apparatus that can effectively prevent a substrate from being flexed, while being exchanged and transferred.
A second object of the present invention is to provide a substrate transfer apparatus which substrate holder does not require a complicated and heavy vertical movement mechanism. The transfer apparatus can also transfer a substrate safely without damaging the substrate, and without deteriorating the flatness of the substrate holder surface even when the space available on the substrate mount surface area of the substrate holder is small.
A third object of the present invention is to provide an exposure apparatus that allows the exchange of a sub
Nguyen Henry Hung
Nikon Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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