Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
2000-11-15
2002-06-18
Sikes, William L. (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S059000
Reexamination Certificate
active
06407782
ABSTRACT:
CROSS REFERENCE
This application claims the benefit of Korean Patent Application No. 1999-0050513, filed on Nov. 15, 1999, under 35 U.S.C. § 119, the entirety of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to a liquid crystal display device, and more particularly, to an array substrate having color filters for use in a liquid crystal display (LCD) device and a method of manufacturing the same.
2. Description of Related Art
A typical LCD device includes upper and lower substrates with a liquid crystal layer interposed therebetween. The upper substrate includes a color filter and a common electrode. The lower substrate includes a switching element and a pixel electrode and is called an array substrate. The lower and upper substrates are assembled after being formed separately. During the forming processes the upper substrate experiences some heating treatment such as pre-bake, exposure to light, post-bake and so on, mainly for formation of color filters, which may result in deformation of the elements of the upper substrate, which causes misalignment for assembling of the lower and upper substrates.
In this aspect, the lower substrate or array substrate having color filters is suggested.
FIG. 1
is a plan view of the conventional array substrate having color filters. On the substrate
11
, gate and data lines
13
and
15
cross each other in the matrix and the near the cross points there are formed thin film transistors “T”, each of which is comprised of a gate electrode
17
which is a portion of the gate line
13
, an active layer
19
, a source electrode
21
, and a drain electrode
23
. For the simplicity, there is shown only one transistor “T”.
A pixel electrode
25
, which is connected to the drain electrode
23
via a contact hole
27
, is formed in a pixel region defined by the gate and data lines
13
and
15
.
Under the pixel electrode
25
is positioned a color filter
29
which partially overlaps the gate and data lines
13
and
15
. A black matrix
31
is formed along the gate line
13
covering the thin film transistor in order to prevent light from entering the active layer
19
.
FIGS. 2
a
to
2
e
are cross sectional views taken along line II—II of
FIG. 1
showing a fabricating process.
As shown in
FIG. 2
a
, on the substrate
11
a gate line
13
having gate electrode
17
is formed and the gate insulating layer
18
is formed on the gate line
13
. On the gate insulating layer
18
over the gate electrode
17
an active layer
19
is formed, and at the end portions of the active layer
19
the source and drain electrodes
21
and
23
are formed, which defines an intermediate structure. The source electrode
21
is elongated from the data line
15
. Next, a first protecting layer
20
of insulating material is formed over the intermediate structure.
And then, as shown in
FIG. 2
b
, a color filter layer
29
is formed on a pixel region defined by the gate and data lines
13
and
15
. The color of the filter layer is one of green (G), red (R) or blue (B) and overlaps the gate and data lines
13
and
15
except over the active layer
19
and a portion
27
over the drain electrode
23
.
Next, a black matrix
31
is formed over the active layer
19
. Chrome, CR, is generally used for the black matrix
31
, since it has a low value of light reflection.
Next, a second protecting layer
33
of benzocyclobutene (BCB) is formed and a drain contact hole corresponding to the portion
27
is formed by etching the first and second protecting layers
20
and
33
.
Next, as shown in
FIG. 2
e
, a pixel electrode
25
of transparent conductive material is formed while being connected to the drain electrode
23
through the contact hole
27
.
The color filter layer can be formed in the array substrate by the process explained above, and misalignment can be reduced. However, in this type of array substrate, two protecting layers
20
and
33
are necessary, which requires more complicated processing.
It should be noted that the parasite capacitance between the pixel electrode
25
and the data line
15
, which causes cross talk, is required to be reduced.
SUMMARY OF THE INVENTION
To overcome the problems described above, embodiments of the present invention provide array substrates (and methods of making the same) for use in a liquid crystal display device, which have a structure that can simplify the manufacturing process and reduce the parasitic capacity between the pixel electrode and the data line.
Advantages of the present invention will become more apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
In an aspect of the invention, the present invention provides a method of fabricating an array substrate (as well as the array substrate itself), the method including: forming a gate line having a gate electrode on a substrate; forming a color filter layer on the substrate, the color filter layer spaced apart from the gate line; forming a first insulating layer on the color filter layer and the gate line; forming a semiconductor layer and ohmic contact layer sequentially on the gate electrode; forming a data line crossing the gate line; forming source and drain electrodes on the ohmic contact layer; wherein the formation of the data line and the source and drain electrodes completes an intermediate structure; forming a protecting layer of transparent insulating material on the intermediate structure, the protecting layer having a drain contact hole at a corresponding position of the drain electrode; and forming a pixel electrode on the protecting layer that contacts the drain electrode through the drain contact hole. Such an array substrate eliminates a need for separate or discrete black matrix elements because the arrangement permits the gate and data lines to also perform the light blocking function of the black matrix.
In an another aspect of the invention, the present invention provides a method of fabricating an array substrate (as well as the substrate itself) for an LCD device, the method including: forming a light shielding layer having a shape of an island on a substrate; forming a buffer layer on the substrate and the light shielding layer; forming an active layer on the buffer layer over the light shielding layer, the active layer having an island shape; forming a first insulating layer on the active layer and the buffer layer; forming a gate electrode on the first insulating layer; forming a color filter spaced apart from the gate electrode on the same plane as the gate electrode to complete an intermediate structure; forming a gate insulating layer of transparent insulating material on the intermediate structure, the gate insulating layer having first and second contact holes; forming the source and drain electrodes on the protecting layer, the source and drain electrodes connecting to the active layer via the first and second contact holes, respectively; forming a protecting layer of transparent insulating material on the source and drain electrodes, the protecting layer having a drain contact hole exposing the drain electrode; forming a pixel electrode on the protecting layer, the pixel electrode connecting to the drain electrode through the drain contact hole.
In an another aspect of the invention, the invention provides a method for fabricating an array substrate (as well as the array substrate itself), for an LCD device, the method including: forming a light shielding layer on a substrate; forming a first insulating layer on the light shielding layer; forming an active layer on the first insulating layer; forming a second insulating layer on the active layer; forming a gate electrode on the second insulating layer; formi
Birch & Stewart Kolasch & Birch, LLP
LG. Philips LCD Co. Ltd.
Nguyen Hoan C.
Sikes William L.
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