Semiconductor device manufacturing: process – Making device or circuit emissive of nonelectrical signal – Including integrally formed optical element
Reexamination Certificate
2000-12-20
2003-10-14
Tsai, Jey (Department: 2812)
Semiconductor device manufacturing: process
Making device or circuit emissive of nonelectrical signal
Including integrally formed optical element
C438S066000
Reexamination Certificate
active
06632696
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an active matrix substrate plate used in liquid crystal display apparatuses and a manufacturing method therefor, and relates in particular to an active matrix substrate plate having superior properties made by a manufacturing process based on simplified processing steps and improved yield.
2. Description of the Related Art
Active matrix type liquid crystal display apparatus using thin film transistors (abbreviated as TFT hereinbelow) as switching elements is constructed by placing a color filter substrate plate opposite to an active matrix substrate plate, in which independent pixel regions containing a TFT and a pixel electrode in each pixel region are arranged in a matrix, with an intervening liquid crystal layer. Also, a light blocking layer is provided on the color filter substrate plate or on the active matrix substrate plate in the TFT section and the boundary region in each pixel region.
An example of the circuit arrangement of the active matrix substrate plate is shown in FIG.
182
. In
FIG. 182
, this active matrix substrate plate is formed such that a plurality of scanning lines
1011
are formed on a transparent insulation substrate plate and a plurality of parallel signal lines
1031
are formed on the transparent insulating substrate plate so as to cross the scanning lines at right angles across the gate insulation layer (not shown), and near the intersection of the scanning line and the signal line, an inverted staggered structure TFT
1060
comprised by a gate electrode
1012
, an island-shaped semiconductor layer opposing the gate electrode across the gate insulation layer, and a pair of drain electrodes
1032
and source electrodes
1033
separated by a channel gap above the semiconductor layer. And in a window section Wd surrounded by a scanning line
1011
and a signal line
1031
, there are provided a pixel electrode
1041
and an accumulation capacitance section
1070
, in such a way that the gate electrode
1012
is connected to the scanning line
1011
, the drain electrode
1032
to the signal line
1031
, and the source electrode
1033
to the pixel electrode
1041
.
The window section Wd and the scanning line
1011
and the signal line
1031
surrounding the window section, the region comprised by TFT
1060
are referred to as the “pixel region Px,” hereinbelow. A plurality of such pixel regions Px are arranged next to each other in a matrix pattern to construct a display surface Dp of the liquid crystal display apparatus.
The scanning lines
1011
are extended outside of the display surface Dp, and at the start end located at its tip, the scanning line terminal
1015
exposed on the surface of the active matrix substrate plate is formed. Also, each signal line
1031
is extended outside of the display surface Dp, and at the start end located at its tip, the signal line terminal
1035
exposed on the surface of the active matrix substrate plate is formed.
On the outside of the display surface Dp, a protective transistor
1080
may sometimes be attached for protecting the TFT connected to each signal line and scanning line, in case of excess current flow. And, the adjacent signal lines
1031
, for the purpose of dispersing unexpected electrical shock and protecting the TFT in the pixel region, may sometimes be connected electrically to each other at the outside of the display surface Dp with a high resistance line.
On the outer peripheral section of the display surface Dp, for the purpose of preventing difficulties such as shorting between layers caused unexpected electrical shock generated on the active matrix substrate plate during the production by dispersing over all the wiring, or for the purpose of inspecting circuit defects, there are provided various kinds of peripheral circuits such as a gate-shut bus line
1091
for linking each scanning line
1011
, a drain-shunt bus line
1092
for linking each signal line
1031
, a connection section for connecting the gate-shunt bus line and the drain-shut bus line, inspection pads
1094
and
1095
for scanning lines and signal lines, respectively, and when manufacturing is completed, the peripheral circuits excepting the inspection pads are removed along with the substrate plate edge pieces.
The active matrix substrate plate having its edge pieces cutoff excepting the inspection pads is processed in such a way that respective scanning line terminals
1015
are connected to a not-shown scanning line driver, and the signal line terminals
1035
are connected to a not-shown signal line driver, and according to signals from respective drivers, specific individual pixel signals are input into the pixel electrode
1041
through each TFT
1060
in the pixel region.
The pixel electrode
1041
is disposed opposite to a common electrode
1014
, and the liquid crystal in the pixel region is driven by applying a potential difference between the electrodes. There are two types of arrangement of the pixel electrode and the common electrode. In one type of configuration, as shown in
FIG. 183A
, the pixel electrode
1041
formed on the active matrix substrate plate and the common electrode
1014
formed over the entire display region of the color filter substrate plate are placed opposite to each other across the liquid crystal Lc, and this configuration is commonly called “twisted nematic type (referred to TN-type hereinbelow)”. The other configuration is, as shown in
FIG. 183B
, pixel electrode
1041
formed in a comb-teeth shape and the common electrode
1014
formed in a comb-teeth shape on the active matrix substrate plate are placed opposite to each other non-contactingly. This configuration is commonly called “in plane switching method” (referred to as the IPS type hereinbelow).
TFT
1060
has a gate electrode
1012
extending from the scanning line
1011
in each pixel region Px, an electrode (it is referred to as the drain electrode in the following)
1032
extending from the signal line
1031
, an electrode (it is referred to as the source electrode, in the following)
1033
connected to the pixel electrode
1041
, and when a scanning line signal is transmitted to the gate electrode
1012
, drain electrode
1032
and source electrode
1033
selectively become conductive so that a pixel signal forwarded from the signal line
1031
is transmitted to the pixel electrode
1041
, and the liquid crystal is driven by the potential difference generated between the pixel electrode
1041
and the common electrode
1014
.
The accumulation capacitance section
1070
is comprised by an accumulation capacitance electrode
1071
and a common accumulation electrode
1072
, and is provided for the purpose of holding the liquid crystal driving potential until the next selection signal is applied on the gate electrode
1012
by preventing, when the scanning line
1011
becomes non-selective, fluctuations in the potential caused by leaking of the liquid crystal driving potential applied on the pixel electrode
1041
through the TFT
1060
and the like.
FIG. 182
shows a gate-storage type of capacitance accumulation in which the common accumulation electrode
1072
is connected to the forestage scanning line, but a common-storage type of capacitance accumulation in which the common accumulation electrode
1072
is connected to the common wiring
1013
may sometimes be used.
An example (for example, a Japanese Unpublished Patent Application, First Publication, Hei 9-120083) of manufacturing steps of active matrix substrate plate for a conventional TN-type liquid crystal display apparatus having the circuit configuration described above will be explained with reference to
FIGS. 184A-184E
. In this case, a combination of patterning and etching steps (referred to simply as etching hereinbelow) based on film deposition and photolithography technique is regarded as one processing step. Also, in the following explanations, the location where the pixel region
1041
of the active matrix substrate plate is formed will be referred to as the window W
Doi Satoshi
Hamada Tsutomu
Harano Toshihiko
Hayase Takasuke
Ihara Hirofumi
Hayes & Soloway P.C.
NEC Corporation
Tsai Jey
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