Radiation imagery chemistry: process – composition – or product th – Imaging affecting physical property of radiation sensitive... – Forming nonplanar surface
Reexamination Certificate
2000-12-22
2003-09-09
Huff, Mark F. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Imaging affecting physical property of radiation sensitive...
Forming nonplanar surface
C430S005000, C430S017000, C430S022000, C430S030000, C430S031000, C355S053000, C356S399000, C356S400000
Reexamination Certificate
active
06617097
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an exposure method. More particularly, the present invention relates to an exposure method for exposing a flat substrate to a pattern for fabricating a liquid crystal display panel, a plasma display panel, and the like.
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 method for exposing a large-sized glass substrate to element patterns of a display panel, a scanning-type exposure method is known. According to the scanning-type exposure method, exposure is performed 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”).
As an example, scanning exposure of a substrate to a mask pattern at one to one magnification will be described. Assume that the size of an 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 carrying the substrate is 843 mm×890 mm. 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 substrate to a pattern of a 17-inch SXGA liquid crystal display panel. The size of the 17-inch SXGA panel including a circuit pattern surrounding a pixel region is 279.7 mm×347.2 mm.
The size relationship is shown in
FIGS. 7 and 8
.
FIGS. 7 and 8
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. 8
for distinction from the substrate
200
), respectively. As shown in
FIG. 8
, 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. 9
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
that has two 279.7 mm×347.2 mm circuit patterns
101
formed thereon. In
FIG. 9
, the substrate holder
15
a
is omitted.
With reference to
FIG. 9
, an exposure of patterns of 17-inch SXGA liquid crystal display panels 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 scanning exposure, the present invention has an objective of providing an exposure method which can be carried out with reduced number of scanning steps and at enhanced throughput.
According to the present invention, the above-mentioned objective is achieved by allowing a substrate to be placed in sideways (rotated by 900) 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. When the substrate is placed in sideways with respect to the scanning direction, or the substrate holder, it is acceptable even when areas other than an effective exposure area of the substrate should project out from the substrate holder, since there is no need of precisely controlling flatness of areas of the substrate where they are not exposed to a pattern.
Along with the reference numerals, the present invention is an exposure method for exposing a rectangular substrate (
14
) to a pattern (
30
a
) of a mask (
30
) by transferring a mask stage (
20
) carrying a mask (
30
) formed with the pattern (
30
) and a rectangular substrate holder (
15
a
) carrying the substrate (
14
) in a first direction (X-direction), the method comprising: a step (S
22
) of placing the substrate (
14
) whose longer sides are longer than the shorter sides of the substrate holder (
15
a
), on the substrate holder (
15
a
) such that the longer sides of the substrate (
14
) are generally arranged along the shorter sides of the substrate holder (
15
a
); a step (S
25
) of exposing a first area (
14
a
,
14
b
) of the substrate (
14
) to the pattern (
30
a
) of the mask (
30
) by transferring the mask stage (
20
) and the substrate holder (
15
a
) in the first direction (X-direction); a step (S
26
) of transferring the substrate holder (
15
a
) in a second direction (Y-direction) which is generally perpendicular to the first direction (X-direction); and a step (S
27
) of exposing a second area (
14
c
,
14
d
) of the substrate (
14
), which is adjacent to the first area (
14
a
,
14
b
) along the second direction (Y-direction), by transferring the mask stage (
20
) and the substrate holder (
15
a
) in the first direction (X-direction).
According to the exposure method of the present invention, the number of scanning steps can be reduced, thereby realizing high throughput.
The exposure method of the invention can comply with the recent tendency toward enlargement of the substrate size, and can be applied without enlarging the exposure apparatus. For example, the exposure method of the invention is applicable to a substrate whose shorter side is 680 mm or longer and whose longer side is 880 mm or longer.
The first direction (X-direction) may be parallel to the longer sides of the substrate holder (
15
a
). The first (
14
a
,
14
b
) and second (
14
c
,
14
d
) areas are positioned in a region where the substrate (
14
) is making contact with the substrate holder (
15
a
). Alignment marks are preferably formed in a region where the substrate (
14
) is making contact with the substrate holder (
15
a
).
REFERENCES:
patent: 5471279 (1995-11-01), Takizawa
patent: 5526093 (1996-06-01), Takahashi
patent: 08-167569 (1996-06-01), None
patent: 9-306826 (1997-11-01), None
patent: 11-016820 (1999-01-01), None
Copy of a Jul. 30, 2002 Office Action in connection with corresponding Korean Application, wherein the above-identified references “BA” and “BB” were cited in the office action.
Naraki Tsuyoshi
Nishimura Yasunori
Oketani Taimi
Chacko-Davis Daborah
Conlin, Esq. David G.
Edwards & Angell LLP
Huff Mark F.
Roos, Esq. Richard J.
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