Semiconductor device manufacturing: process – Making device or circuit emissive of nonelectrical signal – Including integrally formed optical element
Reexamination Certificate
2000-07-14
2002-06-25
Le, Vu A. (Department: 2824)
Semiconductor device manufacturing: process
Making device or circuit emissive of nonelectrical signal
Including integrally formed optical element
C438S030000, C438S043000, C438S151000
Reexamination Certificate
active
06410358
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a reflection type liquid crystal display.
2. Description of the Related Art
In recent years, a reflection type liquid crystal display (LCD) has been developed in which incident light from an observer side is reflected by a reflective display electrode so that display is observed.
FIG. 2
is a plan view showing a display pixel and nearby area of an example of the above mentioned reflective type LCD.
FIG. 3
is a cross sectional view, along the line A—A in
FIG. 2
, showing manufacturing steps.
As shown in
FIG. 2
, a TFT is formed in an area close to a crossing point between a gate signal line
51
and a drain signal line
52
. The gate signal line
51
includes a gate electrode
11
and supplies a gate signal to a gate, while the drain signal line
52
includes a drain electrode
16
and supplies a drain signal to a drain. The gate
11
of the TFT is connected to the gate signal line
51
. The drain
13
d
is connected to the drain signal line
52
, while the source
13
s
is connected to a reflection display electrode
28
.
The reflection display electrode
28
preferably has an uneven surface, rather than an even surface, so that incident light can be reflected in multiple directions. With such an arrangement, the display of the reflection type LCD (Liquid Crystal Display) can be observed from a larger area, so that a larger viewing angle can be ensured.
Referring to FIGS.
3
(
a
) to
3
(
d
), an example of manufacturing steps for the above described reflection type LCD will be described.
Step
1
(FIG.
3
(
a
)): on an insulating substrate
10
, there are sequentially formed a first gate electrode
11
, a gate insulating film
12
, and an active layer
13
, wherein the insulating substrate
10
comprises a quartz glass, a non-alkali glass, and so on, the first gate electrode
11
comprises a refractory metal (Cr, Mo, and so on), the gate insulating film
12
comprises a SiN film and a SiO
2
film, and the active layer
13
comprises an island-shaped polycrystalline silicon film.
Then, in the active layer
13
, there are formed a channel
13
c
above the first gate electrode
11
, and a source
13
s
and a drain
13
d
at the respective sides of the channel
13
c
, wherein the source
13
s
and the drain
13
d
are formed through ion implantation.
Further, on the channel
13
c,
there is formed a stopper insulating film
14
, comprising a SiO
2
film, as a mask covering the channel
13
c
for preventing ion intrusion at the time of ion implantation.
Covering the entire surface of the gate insulating film
12
, the active layer
13
, and the stopper insulating film
14
, there is formed an interlayer insulating film
15
, comprising laminated SiO
2
film, SiN film and SiO
2
film.
Then, contact holes
16
,
17
are made in the interlayer insulating film
15
at respective positions corresponding to the drain
13
d
and the source
13
s.
The contact hole
16
, corresponding to the drain
13
d,
is filled by metal, specifically, by a single Al layer or sequentially laminated Mo and Al layers, thereby forming a drain electrode
18
. At the same time of the formation of the drain electrode
18
, a second gate electrode
19
is formed on the interlayer insulating film
15
above the channel
13
c
using metal, specifically, a single Al layer or sequentially laminated Mo and Al layers. Note that nothing is filled in the contact hole
17
.
The second gate electrode
19
is connected to the gate signal line
51
on the insulating substrate
10
, via a contact hole
20
, formed in the gate insulating film
12
and the interlayer insulating film
15
as shown in
FIG. 1. A
drain signal line
52
is formed on the interlayer insulating film
15
.
Step
2
(FIG.
3
(
b
)): a first planarization insulating film
21
, made of organic resin, and so on, is formed over the layers formed at Step
1
, and a first resist film
22
is applied thereon. Thereafter, exposure and development processes are applied using a first mask
23
, which has an opening at a position corresponding to the contact hole
17
, followed by etching the first planarization insulating film
21
, thereby forming a contact hole
24
corresponding to the contact hole
17
.
Step
3
(FIG.
3
(
c
)): a second planarization insulating film
25
is formed on the semiconductor film
13
in the contact hole
24
and the exposed first planarization insulating film
21
. A second resist film
26
is then applied on the film
25
. Thereafter, exposure and development processes are applied using a second mask
32
, which has an opening at a position corresponding to a recess
27
(
29
) which is to be formed on an area, on the second planarization insulating film
25
, where a reflection display electrode
28
is to be formed, and the second planarization insulating film
25
is thereafter etched whereby a concave
29
(
27
) is formed (FIG.
3
(
d
)).
With the second resist film
26
subsequently removed, a contact hole
24
, where the reflection display electrode
28
contacts the source
13
s,
is formed, and so are concaves
29
(
27
) in the reflection display electrode formation area. With the above, the reflection display electrode
28
resultantly has an uneven surface. As a result, incident light can be reflected in multiple directions, and a wider viewing angle can thus be achieved.
However, the above described manufacturing method of a reflection type LCD may result in increased costs and labor as it initially requires formation of a contact hole
24
in the first planarization insulating film
21
, and then formation of a second planarization insulating film
25
in a different manufacturing step for subsequent formation of a concave
29
(
27
) therein.
SUMMARY OF THE INVENTION
The present invention aims to provide an efficient method for manufacturing a reflection type LCD having a concave in a reflection film.
According to the present invention, two exposures are applied to a photosensitive resin, using two different masks, before development, whereby two types of concaves each having different depths are formed. This enables reduction of the number of steps in formation of concave with two different depths.
In particular, a concave with one of the two depths is used to constitute a contact hole for connection between a TFT transistor and a reflection film (a reflection electrode) having a size corresponding to a pixel, and a concave with another depth is used as a concave in the reflection electrode.
REFERENCES:
patent: 5407845 (1995-04-01), Nasu et al.
patent: 5691791 (1997-11-01), Nakamura et al.
patent: 5796455 (1998-08-01), Mizobata et al.
patent: 5805252 (1998-09-01), Shimada et al.
patent: 5847789 (1998-12-01), Nakamura et al.
patent: 5880797 (1999-03-01), Yamada et al.
patent: 6037084 (2000-03-01), Ting et al.
patent: 6163405 (2000-12-01), Chang et al.
patent: 0112417 (1984-07-01), None
patent: 11-52402 (1999-02-01), None
Patent Abstract of Japanese Patent Laid-Open Publication No. 09179127.
Patent Abstract of Japanese Patent Laid-Open Publication No. 06294954.
Noritake Kazuto
Yamaji Toshifumi
Cantor & Colburn LLP
Le Vu A.
Pyonin Adam
Sanyo Electric Co,. Ltd.
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