Radiant energy – Invisible radiant energy responsive electric signalling – Semiconductor system
Reexamination Certificate
2002-05-10
2004-07-06
Gagliardi, Albert (Department: 2878)
Radiant energy
Invisible radiant energy responsive electric signalling
Semiconductor system
C250S370080, C250S370110, C438S073000
Reexamination Certificate
active
06759660
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to electromagnetic wave capturing devices which detect electromagnetic waves including radiation such as X-rays, visible light, and infrared light. The invention also relates to composite active matrix substrates for use in the electromagnetic wave capturing devices, and methods for manufacturing the composite active matrix substrates.
BACKGROUND OF THE INVENTION
Conventionally, an active-matrix substrate, which is provided with pixel electrodes and switching elements disposed in a two-dimensional manner, finds wide application in devices such as a display device and a capturing device. For example, demand for the active matrix substrate as monitors for an audio/visual device and an office automation device has been rapidly increasing. Examples of such a display device and a capturing device include liquid crystal display devices (LCDs: Liquid Crystal Displays), which are expected for application to a flat TV, and x-ray capturing devices (FPXDs: Flat Panel X-ray Detectors), which are capable of directly reading out x-ray images in the form of electric signals without an film.
The active matrix substrate for use in such a display device and a capturing device includes thin film transistors (TFTs) of metal wiring and semiconductor, which are precisely arrayed in a matrix pattern on an insulating substrate such as a glass substrate. Manufacture of the active matrix substrate requires highly sophisticated processing techniques such as photolithography and expensive manufacturing equipment. This has made it difficult to manufacture a large-area active-matrix substrate because the yield dropped drastically as the area or resolution of the active-matrix substrate was increased. Another problem is that once the manufacturing equipment is built, it is impossible to manufacture an active-matrix substrate which is larger than the substrate size suitable for the manufacturing equipment. That is, it has been difficult to manufacture a large active-matrix substrate to accommodate the increased size of display devices or capturing devices.
As a counter-measure for these problems, there have been proposed methods of forming a composite active-matrix substrate by connecting a plurality of small active-matrix substrates. For example, “Large Area Liquid Crystal Display Realized by Tiling of Four Back Panels (Proceedings of the 15th International Display Research Conference (ASIA DISPLAY '95, pp. 201-204 (1995)))” (reference 1) discloses an arrangement of a composite active-matrix substrate for use in liquid crystal display devices. Further, U.S. Pat. No. 5,827,757 (reference 2), published on Oct. 27, 1998, discloses a method for manufacturing a composite active-matrix substrate and an x-ray capturing device utilizing the composite active-matrix substrate.
The active-matrix substrate described in the above reference 1, as shown in FIGS.
13
(
a
) through
13
(
c
), is fabricated as follows: after four small active-matrix substrates
101
, with their element bearing sides
101
a
facing down, are aligned on a stage
103
with a vacuum chuck, a back side (upper side in FIG.
13
(
a
)) of the active-matrix substrates
101
is bonded to a base substrate
102
with an adhesive resin
105
. Here, the adhesive resin
105
contains a spacer
104
. Further, an ultraviolet curable resin is used for the adhesive resin
105
.
Meanwhile, the composite active-matrix substrate described in the above reference 2, as shown in FIGS.
14
(
a
) through
14
(
g
), is made up of a plurality of small active-matrix substrates
111
bonded to a base substrate
112
. Specifically, this composite active-matrix substrate is fabricated in the following manner: after an edge of the active-matrix substrate
111
whose element bearing side is covered with a protecting film
121
is cut by dicing and polished (see FIGS.
14
(
a
) and
14
(
b
)), the plurality of active-matrix substrates
111
, with their element bearing sides facing down, are aligned on a stage
113
and connected to each other with an adhesive resin
141
which fills a gap between the active-matrix substrates
111
(see FIGS.
14
(
c
) and
14
(
d
)). Thereafter, a back side (upper side in FIG.
14
(
d
)) of the plurality of active-matrix substrates
111
is bonded to a base substrate
112
with an adhesive resin
131
. Then, after the active-matrix substrates
111
are removed from the stage
113
, the protecting film
121
is peeled off from the active-matrix substrates
111
(see FIGS.
14
(
e
) through
14
(
g
)). Here, formation of a large number of orderly openings (holes for releasing an adhesive resin)
112
a
prevents air bubbles from being trapped in the adhesive resin
131
which fills a spacing between the active-matrix substrate
111
and the base substrate
112
, and helps excess adhesive resin
131
to escape.
However, the foregoing conventional composite active-matrix substrates and manufacturing methods have the following problems. For example, the composite active-matrix substrate described in the reference 1 appears to be manufactured in such a way that the plurality of active-matrix substrates
101
aligned together, coated with the adhesive resin
105
having fluidity, are bonded to the base substrate
102
. Here, the plurality of active-matrix substrates
101
must be bonded with the base substrate
102
in a state where a distance between these two substrates is at the distance of a gap determined by a spacer. This causes a problem that the adhesive resin
105
seeps out (pressed out) of the active-matrix substrate
101
. As a result, it becomes difficult to prevent air bubbles from being trapped in the adhesive resin
105
, and cleaning of the excess adhesive resin
105
will be required. This results in a problem that workability suffers significantly.
On the other hand, in the composite active-matrix substrate described in the above reference 2, theoretically, a large number of openings
112
a
formed in advance on the base substrate
112
can prevent air bubbles from being trapped, and excess adhesive resin
131
can escape through the openings
112
a
when the base substrate
112
and the active-matrix substrate
111
are bonded. However, in cases where a comparatively large composite active-matrix substrate is to be manufactured, the base substrate
112
cannot be pressed down (toward the active-matrix substrate
111
) uniformly over the surface when it is bonded. This results in a problem that air bubbles and the adhesive resin
131
cannot be released properly at portions of the base substrate
112
where the applied pressure is weaker, or at thinner portions of the base substrate
112
. In addition, forming the large number of openings
112
a
on the base substrate
112
increases manufacturing costs. Further, cleaning of excess adhesive resin
131
which has seeped out through the opening
112
a
is still required, resulting in a problem that workability suffers significantly.
Further, in the composite active-matrix substrate described in the above reference 2, a rubber squeegee (not shown) is used to fill a gap between the small active-matrix substrates
111
with the adhesive resin
141
. This causes problems that the adhesive resin
141
is likely to spread to the top surface (element bearing side) of the active-matrix substrate
111
, and an external force is applied to the active-matrix substrate
111
through the rubber squeegee. Thus, filling of the adhesive resin
141
required an extremely thick protecting film
121
which covered the top surface of the active-matrix substrate
111
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a composite active-matrix substrate of a structure in which a plurality of small active-matrix substrates are fixed on a base substrate, which can be fabricated without such deficiencies as seeping of an adhesive resin (adhesive filler) used to fix the small active-matrix substrates, or trapping of air bubbles. Another object of the present invention is to provide a method for manufacturing such a composite ac
Izumi Yoshihiro
Teranuma Osamu
Conlin David G.
Gagliardi Albert
Roos Richard J.
Shimadzu Corporation
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