Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2001-09-12
2004-10-26
Kim, Robert H. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S183000, C349S184000, C349S185000, C349S186000
Reexamination Certificate
active
06809785
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application(s) No(s). P2000-281023 filed Sep. 14, 2000, and P2000-36069 filed Nov. 28, 2000, which application(s) is/are incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
The present invention relates to technology for shortening the manufacturing process for semipermeable liquid crystal display devices by forming surface irregularities on the reflective electrode simultaneously with forming openings on the permeable section of the pixel in the interlayered insulating film on silicon film formed with the source and drain of the thin film transistor.
2. Description of the Related Art
The drive side of the TFT (thin film transistor) substrate of the active matrix type semipermeable liquid crystal display device of the related art having a reflective electrode composed of a reflective diffusion plate formed with surface irregularities, and also having a transparent electrode made from transparent conductive film in the transparent section of the pixel is fabricated as shown in FIG.
12
A through FIG.
12
I. The process for fabricating liquid crystal devices having a pixel structured from a bottom gate type TFT is shown in FIG.
12
A through
FIG. 12I
, however a pixel with a top gate type structure TFT is fabricated in basically the same process.
As shown in
12
A, a metallic film is first formed on a transparent substrate
1
, and a gate G and an auxiliary capacitor electrode Cs formed by etching using photolithography, a gate insulation film
2
deposited, and a polysilicon film
3
formed.
Next, to prevent doping of impurities into the channels during impurity doping of the source and drain regions, a stopper
4
is formed to self-align with the gate G on the polysilicon film comprising the channels, and the source region and drain region are doped with impurities.
Islands shapes are then formed separately on the polysilicon film
3
using the photoresist process and the etching process, and a low temperature thin film transistor (TFT) is formed.
The interlayered insulator film
5
is formed next in FIG.
12
B. Next, in order to form contact holes and an opening for the pixel transparent section, a photoresist layer
6
is first of all formed on the interlayered insulator film
5
, and the photoresist layer
6
is patterned in
FIG. 12C
by the photolithographic method using as a pattern~mask, to form contact holes and an opening for the pixel permeable section T as the photomask. Etching is then performed using the interlayered insulator film
5
as the etching mask, and contact holes H
1
and the pixel permeable section T opening are formed (
FIG. 12D
) .
The metallic film is then formed using a stopper etc. A signal line and source electrode S
1
connecting to the TFT source S by way of the contact hole H
1
are formed by etching, and a drain source electrode D
1
connecting to the drain D of the TFT by way of the contact hole H
1
is formed by etching as in FIG.
12
E.
The irregularities forming the base of the surface irregularities of the reflecting electrode having a reflective diffuser function are formed as described next using two layers of photoresist material. A first layer
7
forming the basic structure of the irregular shape is formed by photolithography using the photoresist material in FIG.
12
F. The photomask is used to make openings for a second collector hole
2
and pixel permeable section T for conduction between the source electrode S
1
and drain electrode D
1
. Next, a second layer
8
for improving the reflection is formed as shown in
FIG. 12G
by photolithography using a photoresist material identical to the first layer
7
. The mask is utilized to make openings for the third collector hole H
3
and pixel permeable section T for connection with the drain electrode D
1
. A surface irregularity (rough) section is in this way formed from the first layer
7
and second layer
8
structure.
A transparent conducting film
9
constituting the transparent electrode of the pixel permeable section T is next formed by sputtering, etc. This transparent conducting film
9
connects to the drain electrode D
1
and contact hole H
3
as shown in FIG.
12
H. The transparent conducting film
9
also forms the reflecting section of the pixel and may also be used as the base material (or underlayer) of the reflecting electrode.
A metallic film such as aluminum or silver having high reflectivity is next deposited on the reflecting section R of the pixel, and a reflecting electrode
10
is formed as in
FIG. 12I
by photolithography.
The drive side of the TFT substrate is in this way completed. A polarizing film is coated on this TFT substrate, and opposing substrate formed of the color filter and opposing transparent electrode, and a polarizing process is performed, both the substrates are overlapped on each other using a gap material to maintain a suitable gap between the substrates, liquid crystal injected and sealed to obtain the liquid crystal display panel.
In the fabrication process for the drive side substrate of the TFT (thin film transistor) substrate of the active matrix type semipermeable liquid crystal display device of the related art as shown in FIG.
12
A through
FIG. 12I
, a seventh and an eighth layer are formed from photoresist material to apply specified surface irregularities (rough shape) to a reflecting electrode
10
, and since ultimately a total of three insulating layers including an interlayered insulator film
5
are formed between the reflecting electrode
10
and the silicon film forming the source S and drain D of the TFT, that require patterning processes by respective lithographic methods, and further since a source electrode S
1
, a drain source electrode D
1
, and a reflecting electrode
10
must be formed by separate processes, the problem occurs that many man-hours are required and the manufacturing cost is high.
SUMMARY OF THE INVENTION
Whereupon, the present invention has the object of providing a simple and manufacturing process for an active matrix type semipermeable liquid crystal display device yielding improved productivity.
To achieve the above objects, in the manufacturing process for the semipermeable liquid crystal display device by the inventors of the present invention, a photoresist layer is formed on the interlayered insulator film on the silicon layer forming the source and drain of the TFT device, and corresponding surface irregularities are simultaneously formed on the reflecting electrode of the pixel reflecting section, and opening for the pixel transparent section on the photoresist layer, by patterning with photolithographic methods utilizing a designated photomask on that photoresist layer, so that by forming surface irregularities (rough shapes) on the pixel reflecting section simultaneous with forming an opening on the transparent section of the pixel in the interlayered insulator film, a greatly shortened manufacturing process for liquid crystal devices can in this way be obtained.
The present invention in other words, provides a manufacturing method for an active matrix type semipermeable liquid crystal display device consisting of an interlayered insulator film on the silicon layer forming the source and drain of the TFT, a reflecting electrode formed with surface irregularities (rough sections) on the interlayered insulator film in the pixel reflecting section, and a transparent electrode consisting of a transparent conductive film on the pixel transparent section, wherein in the forming and processing of the interlayered insulator film in the following processes A through D;
A: is a process for forming an interlayered insulator film on a silicon layer forming the source and drain of the TFT;
B: is a process for forming a photoresist layer on the interlayered insulator film;
C: a process for patterning the photoresist layer by the photolithographic method wherein, in a process using a mask formed with a pattern below the resolution limit in the section forming the reflecting electrode, t
Kim Robert H.
Nguyen Hoan
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