Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Amorphous semiconductor material
Reexamination Certificate
2003-01-16
2003-12-16
Pham, Long (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Amorphous semiconductor material
C257S066000, C349S192000
Reexamination Certificate
active
06664568
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims the priority benefit of Taiwan application serial no. 91102060, filed Feb. 6, 2002.
BACKGROUND OF INVENTION
1. Field of Invention
The present invention relates to a thin film transistor liquid crystal display (TFT-LCD) pixel structure. More particularly, the present invention relates to a laser repair facilitated pixel structure and repairing method.
2. Description of Related Art
A thin film transistor liquid crystal display (TFT-LCD) mainly includes a thin film transistor (TFT) array substrate board, a color filter array substrate board and a liquid crystal layer. The TFT array substrate board comprises an array of thin film transistors and a pixel electrode for each thin film transistor. The thin film transistor further comprises a gate electrode, a channel layer, a source terminal and a drain terminal. The thin film transistor serves as a switching element for each liquid crystal display cell.
FIG. 1
is a schematic top view of a conventional pixel structure. As shown in
FIG. 1
, a pixel structure mainly comprises a thin film transistor
101
and a pixel electrode
110
. The pixel is controlled through a scan line
102
and a data line
104
. The thin film transistor
101
of the pixel structure further includes a gate terminal
102
a
, a source terminal
104
a
and a drain terminal
104
b
. The drain terminal
104
a
connects electrically with the data line
104
. The gate electrode
102
a
of the thin film transistor
101
connects electrically with the scan line
102
. The source terminal
104
b
of the thin film transistor
101
connects electrically with the pixel electrode
110
. Each pixel electrode
110
corresponds with a thin film transistor
101
.
When a break
120
on the data line
104
occurs, a repairing step needs to be conducted so that the ends of the data line
104
at the break region
120
are electrically connected back together. Several methods of repairing a severed data line have been developed. One of the methods is explained with reference to
FIGS. 2A
to
2
C below.
FIGS. 2A
to
2
C are schematic cross-sectional views along line I-I″ of
FIG. 1
showing the steps for repairing a broken data line using a laser beam. A data line
104
having a broken region
120
on the dielectric layer
106
of a substrate board
100
is shown in
FIGS. 1 and 2A
. The dielectric layer
106
and the gate insulation layer of the thin film transistor
101
are formed together. The data line
104
further includes another dielectric layer
108
formed in the same process of depositing a protective layer between the thin film transistor
101
and the pixel electrode
110
.
To carry out a laser repair, openings
200
a
and
200
b
are formed in the dielectric layer
108
above the data line
104
near each end of the broken region
120
using a laser as shown in
FIG. 2B
so that a portion of the data line
104
is exposed. Since the openings
200
a
and
200
b
are formed by a laser burning operation, some material from the dielectric layer
108
piles up to form protruding ledges
201
near the upper corners.
As shown in
FIG. 2C
, a laser chemical vapor deposition (laser CVD) is carried out to form a conductive layer
202
over the interior surface of the openings
200
a
and
200
b
and the exposed dielectric layer
108
. Through the conductive layer
202
, broken ends of the data line
104
within the broken region
120
are reconnected electrically.
Due to the formation of protruding ledges
201
near the upper corners of the openings
200
a
and
200
b
, the conductive layer
202
formed by laser CVD also includes a prominent peak or spike there. The pointed peak or spike in the protruding area is electrically conductive and hence may contact with color filter to form a short circuit route. Ultimately, performance of the device is affected. Occasionally, the protrusion
201
may even lead to a short circuit between the upper and lower panel of a liquid crystal display. In addition, if the broken region within the data line
104
is too long, a conventional laser CVD may not bridge the gap reliably. Hence, yield of the laser repair is often compromised.
SUMMARY OF INVENTION
Accordingly, one object of the present invention is to provide a laser repairing method capable of reconnecting a broken data line without leading to possible subsequent short-circuiting between the upper and lower substrate board of a liquid crystal display panel.
A second object of this invention is to provide a laser repair facilitated pixel structure capable of tackling low yield problem resulting from the appearance of a long broken section on the data line being repaired.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a pixel structure on a substrate board. The pixel structure includes a thin film transistor, a scan line, a pixel electrode, a data line, a conductive line, a first dielectric layer and a second dielectric layer. The thin film transistor is formed over the substrate board. The thin film transistor further includes a gate electrode, a source terminal and a drain terminal. The scan line is formed over the substrate board and electrically connected to the gate electrode. The pixel electrode is formed over the substrate board and positioned next to the thin film transistor. The data line is formed over the substrate board and electrically connected to the pixel electrode via the source/drain terminals. The conductive line is formed underneath the data line. The conductive line has a connective region and a repair section at each end of the connective region. The repair sections protrude over the data line covered range. The repair section at each end of the conductive line may form on the same side as the data line or on the opposite side of the data line. Alternatively, the conductive line may be designed to have a width greater than the data line so that the conductive line outside the data line covered area can also serve as part of the repair section. The first dielectric layer is formed over the substrate board for electrically isolating the conductive line from the data line. The second dielectric layer is also formed over the substrate board to cover the data line. The two repair sections at each end of the conductive line within the pixel structure serve as areas for laser repair according to this invention.
When a break in the data line occurs, the broken data line is repaired by carrying out the following steps. First, the first dielectric layer and the second dielectric layer above the two repair sections are burnt away using a laser beam to form a first opening and a second opening that expose the data line and repair section. Thereafter, a laser chemical vapor deposition is carried out to form a conductive layer over the exposed surface inside the first opening and the second opening. Hence, the two repair sections and the data line are electrically connected. Through the special structural design between the conductive line and the repair sections, the data line can be easily repaired.
This invention provides an alternative pixel structure on a substrate board. The pixel structure includes a thin film transistor, a scan line, a pixel electrode, a data line, a conductive line, a conductive structure, a first dielectric layer and a second dielectric layer. The thin film transistor is formed over the substrate board. The thin film transistor further includes a gate electrode, a source terminal and a drain terminal. The scan line is formed over the substrate board and electrically connected to the gate electrode. The pixel electrode is formed over the substrate board and positioned next to the thin film transistor. The data line is formed over the substrate board and electrically connected to the pixel electrode via the source/drain terminals. The conductive line is formed underneath the data line. The conductive line has a connective region. Each end of the connective region of the conduc
AU Optronics Corporation
Jiang Chyun IP Office
Pham Hoai
Pham Long
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