Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-06-27
2002-06-04
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S110000, C349S111000, C349S043000
Reexamination Certificate
active
06400434
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflection type display device constituted by semiconductor devices using thin film semiconductors, and particularly to a structure of a reflection type liquid crystal display device. Also, the present invention relates to an electronic device using the reflection type display device.
2. Description of the Related Art
In recent years, since a portable information terminal equipment (portable equipment) such as a mobile computer and a portable telephone (including PHS) has rapidly come into wide use, a reflection type liquid crystal display device attracts a great deal of attention. Since the reflection type liquid crystal display device does not require backlight as a light source, it is possible to make the portable equipment miniaturized, lightened, and decreased in consumption of electric power.
Here, a conventional process of manufacturing a pixel matrix circuit constituting a reflection type liquid crystal display device will be described in brief. The pixel matrix circuit is a circuit in which thin film transistors (TFT) for controlling an electric field applied to a liquid crystal are arranged in matrix, and constitutes an image display region of a liquid crystal display device.
In FIG.
2
(A),
201
denotes a substrate having an insulating surface,
202
denotes an active layer of a first pixel TFT, and
203
denotes an active layer of a second pixel TFT. A distance between the first pixel TFT and the second pixel TFT corresponds to a pixel pitch, and has a tendency to become short as the display becomes highly minute.
Reference numeral
204
denotes a gate insulating film. Gate electrodes
205
and
206
are formed thereon. The gate electrodes
205
and
206
are connected to not-shown gate lines. In this way, the state shown in FIG.
2
(A) is obtained.
Next, an impurity ion for giving one conductivity (phosphorus (P) for an N-type, and boron (B) for a p-type) is added into the active layers
202
and
203
. As a result, source regions
207
and
208
, drain regions
209
and
210
, and channel formation regions
211
and
212
are formed (FIG.
2
(B)).
Next, a first interlayer insulating film
213
is formed, contact holes are made, and source electrodes
214
and
215
and drain electrodes
216
and
217
are formed. In this way, the state shown in FIG.
2
(C) is obtained.
Further, a second interlayer insulating film
218
is formed, and a black mask
219
is formed thereon. A third interlayer insulating film
220
is formed thereon, and finally pixel electrodes
221
are formed. The respective pixel electrodes
221
are made of a metal thin film which reflects incident light, so that the pixel electrodes are made to have a function as a reflecting electrode (FIG.
2
(D)).
At this time, the black mask
219
is disposed under a region which is a gap between the pixel electrodes (reflecting electrodes)
221
. In FIG.
2
(D), although the black mask appears to be individual patterns, all the patterns are actually connected in matrix. The black mask
219
arranged in this manner serves to block light leaked from the gap of the pixel electrodes
221
.
Through the above steps, the pixel matrix circuit as shown in FIG.
2
(D) is completed. Then, by a well-known cell assembling step, a liquid crystal is held between the substrate on which the pixel matrix circuit is formed and an opposite substrate, so that a reflection type liquid crystal display device is completed.
As an example different from the structure shown in FIG.
2
(D), it is also possible to use the source electrodes
214
and
215
as black masks by adjusting the source electrodes
214
and
215
to the gaps between the pixel electrodes
221
. However, the line width of the source/drain electrodes has a tendency to be made minute, and further, in view of the patterning precision (affecting the distance of the gap) of the pixel electrode, it may be said that there is a limit to this proposal.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a technique capable of greatly simplifying manufacturing steps of a reflection type liquid crystal display device.
According to an aspect of the present invention, a reflection type display device comprises an active matrix substrate on which a plurality of TFTs are formed, an opposite substrate including an opposite electrode, and a liquid crystal layer held between the active matrix substrate and the opposite substrate, and is characterized in that first wiring lines, second wiring lines, and pixel electrodes constituting the plurality of TFTs are insulated and separated from each other by insulating layers, and at least one of the insulating layers is made of an insulating film in which a carbon-based material or a pigment is dispersed.
According to another aspect of the present invention, a reflection type display device comprises an active matrix substrate on which a plurality of TFTs are formed, an opposite substrate including an opposite electrode, and a liquid crystal layer held between the active matrix substrate and the opposite substrate, and is characterized in that first wiring lines, second wiring lines, and pixel electrodes constituting the plurality of TFTs are insulated and separated from each other by insulating layers, and at least one of the insulating layers is made of an organic resin film in which a carbon-based material or a pigment is dispersed. In the above structure, the organic resin film may be made of one kind or plural kinds of materials selected from the group consisting of polyimide, polyamide, polyimide amide, and acryl.
According to still another aspect of the present invention, an electronic device comprises an active matrix substrate on which a plurality of TFTs are formed, an opposite substrate including an opposite electrode, and a liquid crystal layer held between the active matrix substrate and the opposite substrate, and is characterized in that first wiring lines, second wiring lines, and pixel electrodes constituting the plurality of TFTs are insulated and separated from each other by insulating layers, and at least one of the insulating layers is made of an insulating film in which a carbon-based material or a pigment is dispersed.
According to still another aspect of the present invention, an electronic device comprises an active matrix substrate on which a plurality of TFTs are formed, an opposite substrate including an opposite electrode, and a liquid crystal layer held between the active matrix substrate and the opposite substrate, and is characterized in that first wiring lines, second wiring lines, and pixel electrodes constituting the plurality of TFTs are insulated and separated from each other by insulating layers, and at least one of the insulating layers is made of an organic resin film in which a carbon-based material or a pigment is dispersed.
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patent
Chowdhury Tarifur R.
Fish & Richardson P.C.
Semiconductor Energy Laboratory Co,. Ltd.
Sikes William L.
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