Photocopying – Projection printing and copying cameras – Detailed holder for photosensitive paper
Reexamination Certificate
2001-01-19
2002-12-17
Mathews, Alan A. (Department: 2851)
Photocopying
Projection printing and copying cameras
Detailed holder for photosensitive paper
C355S053000, C355S091000, C269S021000
Reexamination Certificate
active
06496249
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an exposure apparatus. More particularly, the present invention relates to an exposure apparatus used for exposing a pattern onto a flat substrate for fabricating a flat panel such as a liquid crystal display panel and a plasma display panel.
BACKGROUND OF THE INVENTION
Display qualities of recent liquid crystal display panels and plasma display panels are remarkably enhanced. Moreover, the liquid crystal display panels and the plasma display panels are thin and light, and thus are becoming major image display apparatuses as substitutes for CRTs. Particularly, a direct-view type active matrix liquid crystal panel is making progress in enlarging its screen size, and to that end the size of glass substrates used for fabricating the liquid crystal panels are becoming larger as well.
As an exposure apparatus for exposing element patterns of a display panel onto a large-sized glass substrate, a scanning-type exposure apparatus is known. The scanning-type exposure apparatus performs exposure by synchronously scanning a photomask or a reticle having a pattern formed thereon (hereinafter, referred to as a “mask”) and a glass substrate applied with a photosensitive agent such as a photoresist (hereinafter, referred to as a “substrate”).
When a photosensitive agent such as a resist is applied onto a substrate by, for example, a spin coater or the like, the resist often leak into the periphery of the back surface of the substrate. When such substrate with the resist on its back is loaded on a substrate holder of the exposure apparatus, the substrate-holding surface of the substrate holder is contaminated, and the back surface of the substrate and the substrate-holding surface of the substrate holder may not contact closely to each other causing a problem of poor flatness of an exposure area of the substrate.
According to a scanning-type exposure, the number of scanning steps may increase depending on the size of the device pattern and the size of the substrate, which may result in poor throughput. As an example, a scanning-type exposure of a substrate to a mask pattern at one to one magnification size will be described.
Assume that the size of effective exposure area of the mask is 400 mm×700 mm, the size of the substrate is 720 mm×900 mm, and the size of a substrate holder for holding the substrate is 843 mm×890 mm (the whole surface of the substrate holder consists of a vacuum-holding surface). A scanning-type exposure apparatus, which synchronously transfers a mask stage (for supporting and transporting a mask) and a substrate stage (a substrate holder for supporting a substrate), with respect to a projection optical system, is used to expose a pattern of a 17-inch SXGA liquid crystal display panel onto a substrate. The size of the 17-inch SXGA panel including a circuitry pattern surrounding a pixel region is 279.7 mm×347.2 mm.
The size relationship is shown in
FIGS. 13 and 14
.
FIGS. 13 and 14
are schematic views showing the sizes of a rectangular substrate holder
15
a
and a substrate
200
held by the substrate holder
15
a
(which is represented by dotted lines in
FIG. 14
for distinction from the substrate
200
), respectively. As shown in
FIG. 14
, the substrate
200
is loaded on the substrate holder
15
a
such that the longer sides of the substrate
200
are arranged along the longer sides of the substrate holder
15
a.
FIG. 15
is a schematic view for illustrating a manner of printing six 17-inch SXGA panels on the above-described substrate by using a mask
100
which has two 279.7 mm×347.2 mm circuit patterns
101
formed thereon. In
FIG. 15
, the substrate holder
15
a
is omitted.
With reference to
FIG. 15
, a pattern exposure for fabricating a 17-inch SXGA liquid crystal display panel is carried out as follows. First, a first scanning exposure is conducted by synchronously transferring the mask
100
and the substrate
200
in the X-direction as indicated by an arrow
1
to print two circuit patterns
101
on exposure areas
200
a
and
200
b
of the substrate
200
.
Then, the mask
100
and the substrate
200
are transferred back to the exposure initiating positions to perform a second scanning exposure to print a single circuit pattern
101
on an exposure area
200
c
as indicated by an arrow
2
. Since the length of the side of the substrate
200
is 900 mm, two circuit patterns
101
cannot be exposed at the second scanning exposure.
Next, while the substrate
200
is step transferred in the Y-direction, the mask
100
and the substrate
200
are transferred back to the exposure initiating positions to perform a third scanning exposure to print a single circuit pattern
101
on an exposure area
200
d
of the substrate
200
as indicated by an arrow
3
. Finally, two circuit patterns
101
are printed on exposure areas
200
e
and
200
f
as indicated by an arrow
4
.
According to such a conventional exposure method, even when the mask
100
is provided with two circuit patterns
101
, there is a case where only a single circuit pattern
101
can be printed at a time. As a result, the number of scanning exposure increases, limiting improvement of the throughput.
SUMMARY OF THE INVENTION
In view of the current situation of exposure apparatuses, the present invention has an objective of providing an exposure apparatus in which the flatness of a substrate is not deteriorated with a photosensitive agent leaking into the back surface of the substrate, or in which a surface holding the substrate is not contaminated by the same. The present invention also has an objective of providing an exposure apparatus which requires less number of scanning steps and which has improved throughput without any device enlargement.
According to the present invention, a substrate-holding surface of a substrate holder is provided with grooves with which a periphery of a substrate make contact so that a photosensitive agent leaking into the back surface of the substrate can escape into the grooves. Furthermore, a structure of the present invention allows a substrate to be placed in sideways with respect to a substrate holder (placing the longer sides of the substrate in parallel to the shorter sides of the substrate holder) depending on the size of the apparatus and the size of the substrate. Where the substrate is placed in sideways with respect to the substrate holder, it is acceptable even when areas other than an effective exposure area should project out from the substrate holder, since there is no need of precisely controlling flatness of areas of the substrate where no pattern is to be printed.
Along with the reference numerals, the present invention is an exposure apparatus that exposes a pattern of a mask (
10
,
30
) onto a substrate (
14
), comprising: a substrate holder (
15
a
) having a substrate-holding surface to hold the substrate, the substrate-holding surface being provided with a first pair of grooves (
31
,
32
) extending from one end to the other along a first direction (X-direction) and a second pair of grooves (
33
,
34
) extending from one end to the other along a second direction (Y-direction) substantially perpendicular to the first direction; and a substrate stage (
15
) that supports the substrate holder to move in the first direction (X-direction).
The first grooves (
31
,
32
) and second grooves (
33
,
34
) are positioned such that they make contact with the periphery of the substrate (
14
) when the substrate (
14
) is vertically or horizontally placed on the substrate holder (
15
a
). According to this structure, even when a photosensitive agent leaks into the periphery of the back surface of the substrate (
14
), the resist escapes into the first and second grooves (
31
,
32
;
33
,
34
), thereby preventing deterioration of the flatness of the substrate (
14
) or contamination of the substrate-holding surface of the substrate holder (
15
a
). The distance between a pair of first grooves (
31
,
32
) may be equal to the length of the shorter sides of the recta
Naraki Tsuyoshi
Nishimura Yasunori
Oketani Taimi
Conlin David G.
Daley, Jr. William J.
Edwards & Angell LLP
Mathews Alan A.
Sharp Kabushiki Kaishi
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