U.S. patent application number 11/552726 was filed with the patent office on 2007-03-01 for method for manufacturing thin film transistor array panel for display device.
Invention is credited to Bong-Ju Kim, Hyun-Young Kim, Seung-Gyu Tae, Joo-Sun Yoon.
Application Number | 20070048910 11/552726 |
Document ID | / |
Family ID | 28786899 |
Filed Date | 2007-03-01 |
United States Patent
Application |
20070048910 |
Kind Code |
A1 |
Yoon; Joo-Sun ; et
al. |
March 1, 2007 |
Method For Manufacturing Thin Film Transistor Array Panel For
Display Device
Abstract
A gate wire including gate lines, gate electrodes, and gate pads
and extending in a transverse direction is formed on a substrate. A
gate insulating layer is formed thereafter, and a semiconductor
layer and an ohmic contact layer are sequentially formed thereon. A
conductive material is deposited and patterned to form a data wire
inducing data lines intersecting the gate lines, source electrodes,
drain electrodes, and data pads. A protective layer made of silicon
nitride is deposited on the substrate, and an organic insulating
layer made of a photosensitive organic insulating material is
coated on the protective layer. The organic insulating layer is
patterned to form an unevenness pattern on its surface and first
contact holes exposing the protective layer opposite the drain
electrodes. Subsequently, the surface of the organic insulating
layer is treated using inactive gas such as Ar, and then the
protective layer is patterned together with the gate insulating
layer by photo etch using a photoresist pattern to form contact
holes respectively exposing the drain electrodes, the gate pads,
and the data pads. Next, indium-tin-oxide or indium-zinc-oxide is
deposited and patterned to form transparent electrodes, subsidiary
gate pads, and subsidiary data pads respectively connected to the
drain electrodes, the gate pads and the data pads. Finally, a
reflective conductive material is deposited and patterned to form
reflecting films having respective apertures in the pixel area on
the transparent electrodes.
Inventors: |
Yoon; Joo-Sun; (Seoul,
KR) ; Kim; Bong-Ju; (Suwon-city, KR) ; Tae;
Seung-Gyu; (Suwon-city, KR) ; Kim; Hyun-Young;
(Goyang-city, KR) |
Correspondence
Address: |
MACPHERSON KWOK CHEN & HEID LLP
2033 GATEWAY PLACE
SUITE 400
SAN JOSE
CA
95110
US
|
Family ID: |
28786899 |
Appl. No.: |
11/552726 |
Filed: |
October 25, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10509481 |
Mar 23, 2005 |
7129105 |
|
|
11552726 |
Oct 25, 2006 |
|
|
|
Current U.S.
Class: |
438/149 |
Current CPC
Class: |
G02F 1/133555 20130101;
G02F 1/13458 20130101; G02F 1/133553 20130101; G02F 1/136227
20130101; G02F 1/136236 20210101 |
Class at
Publication: |
438/149 |
International
Class: |
H01L 21/84 20060101
H01L021/84 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 2, 2002 |
KR |
10-2002-0018506 |
Claims
1. A method of manufacturing a thin film transistor array panel for
a liquid crystal display, the method comprising: forming a gate
wire including a gate line and a gate electrode connected to the
gate line; depositing a gate insulating layer; forming a
semiconductor layer; forming a data wire including a data line
intersecting the gate lines to define a pixel area, a source
electrode connected to the data line and placed close to the gate
electrode, and a drain electrode placed opposite the source
electrode with respect to the gate electrodes; depositing a
protective layer covering the gate wire or the data wire; forming
an organic insulating layer by spin-coating an organic insulating
material on the protective layer; patterning the organic insulating
layer to form a first contact hole exposing the protective layer
opposite the drain electrode; surface-treating the organic
insulating layer by plasma process using inactive gas; patterning
the protective layer to form a second contact hole exposing the
drain electrode and located inside the first contact hole; and
forming a pixel electrode electrically connected to the drain
electrode through the first and the second contact holes.
2. The method of claim 1, wherein the pixel electrode comprises a
transparent conductive electrode or a reflective conductive
film.
3. The method of claim 2, wherein a surface of the organic
insulating layer has an unevenness pattern when the pixel electrode
has the reflective film.
4. The method of claim 2, wherein the reflective film has an
aperture in the pixel area when the pixel electrode comprises both
the transparent electrode and the reflective film.
5. The method of claim 1, wherein the semiconductor layer comprises
amorphous silicon or polysilicon.
6. The method of claim 1, wherein the gate wire further includes a
gate pad connected to one end of the gate line, the data wire
further includes a data pad connected to one end of the data line,
and the protective layer or the gate insulating layer has a third
contact hole exposing the gate pad or the data pad, and wherein the
thin film transistor array panel further comprises a subsidiary pad
electrically connected to the gate pad or the data pad through the
third contact hole and including substantially the same layer as
the pixel electrode.
7. The method of claim 1, wherein both the data wire and the
semiconductor layer are formed by a photo etch step using a
photoresist pattern with position-dependent thickness.
Description
BACKGROUND OF THE INVENTION
[0001] (a) Field of the Invention
[0002] The present invention relates to a manufacturing method of a
thin film transistor array panel for a display device.
[0003] (b) Description of the Related Art
[0004] At present, a liquid crystal display ("LCD") is one of the
most widely used flat panel displays. An LCD, which includes two
panels having electrodes and a liquid crystal layer interposed
therebetween, controls the transmittance of light passing through
the liquid crystal layer by realigning liquid crystal molecules in
the liquid crystal layer with voltages applied to the electrodes.
Among these LCDs, the most commonly used one provides at least one
electrode on each panel and includes thin film transistors ("TFTs")
switching the voltages applied to the electrodes.
[0005] Generally, a panel with TFTs ("TFT array panel") includes,
in addition to the TFTs, signal wires including gate lines
transmitting scanning signals, data lines transmitting image
signals, gate pads transmitting the scanning signals from external
devices to the gate lines, and data pads transmitting the image
signals from external devices to the data lines. The TFT array
panel further includes, pixel electrodes electrically connected to
the TFTs and located in respective pixel areas defined by the
intersections of the gate lines and the data lines.
[0006] In a reflective LCD or a transflective LCD, the pixel
electrodes are made of a transparent conductive material such as
indium tin oxide ("ITO") and overlap signal wires to ensure
aperture ratio of pixels. Also, an insulating layer made of organic
insulating material with low dielectric constant is formed between
the signal wires and the pixel electrodes to minimize the
interference of the signals transferred through them.
[0007] Moreover, the pixel electrodes of the transflective LCD are
made of using a reflective conductive material such as Al or Ag as
well as ITO, and formed to have embossment for increasing the
reflecting ratio of the pixel electrodes. The embossment of the
reflecting film is formed by providing an organic insulating layer
with unevenness under the pixel electrode.
[0008] However, adhesiveness between the organic insulating layer
and the ITO film is deteriorated when forming the ITO film on the
insulating layer made of the organic insulating material. To solve
the problem, the roughness of the surface of the organic insulating
layer is increased by performing a plasma process before depositing
the ITO film.
[0009] However, contact resistance of a contact exposing the wire
to be connected to the pixel electrode is increased since the
organic material is re-deposited on the wire in the contact during
the plasma process.
SUMMARY OF THE INVENTION
[0010] It is an object of the present invention to provide a TFT
array panel and a manufacturing method thereof having good
adhesiveness between an ITO film and an organic insulating film and
minimizing contact resistance of a contact through which ITO is
electrically connected to a wire.
[0011] In order to solve the problems, the present invention forms
a protective layer under an organic insulating layer and performing
surface-treatment of the organic insulating layer by a plasma
process before deposition of an ITO film under the condition that
the protective layer is remained on a wire.
[0012] In detail, in a method of manufacturing a thin film
transistor array panel according to the present invention a gate
wire including a gate line and a gate electrode connected to the
gate line is formed, a gate insulating layer is deposited, a
semiconductor layer is formed, and a data wire including a data
line intersecting the gate lines to define a pixel area, a source
electrode connected to the data line and placed close to the gate
electrode, and a drain electrode placed opposite the source
electrode with respect to the gate electrodes is formed.
Subsequently, a protective layer is deposited, then an organic
insulating layer is formed by spin-coating an organic insulating
material on the protective layer, the organic insulating layer is
patterned to form a first contact hole exposing the protective
layer opposite the drain electrode, and a surface of the organic
insulating layer is treated by plasma process using inactive gas.
Also, the protective layer is patterned to form a second contact
hole exposing the drain electrode and located inside the first
contact hole and a pixel electrode electrically connected to the
drain electrode through the first and the second contact holes is
formed.
[0013] The pixel electrode may include a transparent conductive
electrode or a reflective conductive film. The surface of the
organic insulating layer preferably has an unevenness pattern when
the pixel electrode has the reflective film. The reflective film
has an aperture in the pixel area.
[0014] The semiconductor layer may include amorphous silicon or
poly silicon. The protective layer may include SiNx or SiOx.
Preferably, the second contact hole may be formed by a photo etch
using a photoresist pattern after forming the first contact
hole.
[0015] It is preferable that the gate wire further includes a gate
pad connected to one end of the gate line, the data wire further
includes a data pad connected to one end of the data line, and the
protective layer or the gate insulating layer has a third contact
hole exposing the gate pad or the data pad. The thin film
transistor array panel preferably further includes a subsidiary pad
electrically connected to the gate pad or the data pad through the
third contact hole and including substantially the same layer as
the pixel electrode.
[0016] Both the data wire and the semiconductor layer may be formed
by a photo etch step using a photoresist pattern with
position-dependent thickness.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is a layout view of a TFT array panel for a
transflective type LCD according to a first embodiment of the
present invention;
[0018] FIG. 2 is a sectional view of FIG. 2 taken along the line
II-II';
[0019] FIGS. 3A, 4A, 5A, 6A, 8A and 9A are layout views of a TFT
array panel for a transflective type LCD in the intermediate steps
of a manufacturing method thereof according to an embodiment of the
present invention;
[0020] FIG. 3B is a sectional view of the TFT array panel shown in
FIG. 3A taken along the line IIIB-IIIB';
[0021] FIG. 4B is a sectional view of the TFT array panel shown in
FIG. 4A taken along the line IV-IV' and illustrates the step
following the step shown in FIG. 3B;
[0022] FIG. 5B is a sectional view of the TFT array panel shown in
FIG. 5A taken along the line VB-VB' and illustrates the step
following the step shown in FIG. 4B;
[0023] FIG. 6B is a sectional view of the TFT array panel shown in
FIG. 6A taken along the line VIB-VIB' and illustrates the step
following the step shown in FIG. 5B;
[0024] FIG. 7 is a sectional view of the TFT array panel shown in
FIG. 6A taken along the line VIB-VIB' and illustrates the step
following the step shown in FIG. 6B;
[0025] FIG. 8B is a sectional view of the TFT array panel shown in
FIG. 8A taken along the line VIIIB-VIIIB' and illustrates the step
following the step shown in FIG. 7;
[0026] FIG. 9B is a sectional view of the TFT array panel shown in
FIG. 9A taken along the line IXB-IXB' and illustrates the step
following the step shown in FIG. 8B;
[0027] FIG. 10 is a layout view of a TFT array panel for a
reflective type LCD according to a second embodiment of the present
invention;
[0028] FIG. 11 is a sectional view of the TFT array panel shown in
FIG. 10 taken along the line XI-XI';
[0029] FIG. 12 is a layout view of a TFT array panel for an LCD
according to a third embodiment of the present invention;
[0030] FIGS. 13 and 14 are sectional views of the TFT array panel
shown in FIG. 12 taken along the line XIII-XIII' and the line
XIV-XIV', respectively;
[0031] FIG. 15A is a layout view of a TFT array panel in the first
step of a manufacturing method thereof according to the third
embodiment of the present invention;
[0032] FIGS. 15 B and 15C are sectional views of the TFT array
panel shown in FIG. 15S taken along the lines XVB-XVB' and
XVC-XVC', respectively;
[0033] FIGS. 16A and 16B are sectional views of the TFT array panel
shown in FIG. 15A taken along the lines XVB-XVB' and XVC-XVC',
respectively, and illustrate the step following the step shown in
FIGS. 15B and 15C;
[0034] FIG. 17A is a layout view of the TFT array panel in the step
following the step shown in FIGS. 16A and 16B;
[0035] FIGS. 17B and 17C are sectional views of the TFT array panel
shown in FIG. 17A taken along the lines XVIIB-XVIIB' and
XVIIC-XVIIC', respectively;
[0036] FIGS. 18A, 19A and 20A and FIGS. 18B, 19B and 20B are
respective sectional views of the TFT array panel shown in FIG. 17A
taken along the lines XVIIB-XVIIB' and XVIIC-XVIIC', respectively,
and illustrate the steps following the step shown in FIGS. 17B and
17C;
[0037] FIG. 21A is a layout view of the TFT array panel in the step
following the step shown in FIGS. 20A and 20B;
[0038] FIGS. 21B and 21C are sectional views of the TFT array panel
shown in FIG. 21A taken along the lines XXIB-XXIB' and XXIC-XXIC',
respectively;
[0039] FIG. 22A is a layout view of the TFT array panel in the step
following the step shown in FIGS. 21B and 21C; and
[0040] FIGS. 22B and 22C are sectional views of the TFT array panel
shown in FIG. 22A taken along the lines XXIIB-XXIIB' and
XXIIC-XXIIC' and illustrate the sequence of the step following the
step shown in FIGS. 21B and 21C, respectively.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0041] Now, TFT array panels and manufacturing methods thereof
according to embodiments of the present invention will be described
with reference to the accompanying drawings, which makes those
skilled in the art to easily carry out the present invention.
[0042] First, a transflective type LCD according to a first
embodiment of the present invention will be described in detail
with reference to FIGS. 1 and 2.
[0043] FIG. 1 is a layout view of a TFT array panel for a
transflective type LCD according to a first embodiment of the
present invention, and FIG. 2 is a sectional view of the TFT array
panel shown in FIG. 1 taken along the line II-II.
[0044] A gate wire is formed on an insulating substrate 10. The
gate wire includes either a single layer preferably made of Ag, Ag
alloy, Al and Al alloy having low resistivity, or multiple layers
including the single layer. The gate wire includes a plurality of
gate lines 22 extending substantially in a transverse direction, a
plurality of gate pads 24 connected to one ends of the gate lines
22 for receiving gate signals from external devices and
transmitting the gate signals to the gate lines 22, and a plurality
of gate electrodes 26 of TFTs connected to the gate lines 22. The
gate wire may overlap pixel electrodes 82 and 86, which will be
formed later, to form storage capacitors, or may include a
plurality of storage electrodes applied with a predetermined
voltage such as a common electrode voltage (which is applied to a
common electrode of an upper panel and referred to as "a common
voltage" hereinafter) from an external source such that the storage
electrodes overlap the pixel electrodes 82 and 86, which will be
described later, to form storage capacitors for improving the
charge storing capacity of pixels.
[0045] The gate wire 22, 24 and 26 is covered by a gate insulating
layer 30 preferably made of SiNx formed on the substrate 10.
[0046] A semiconductor pattern 40 preferably made of amorphous
silicon is formed on the gate insulating layer 30 opposite the gate
electrodes 24, and an ohmic contact layer pattern 55 and 56
preferably made of silicide or n+ hydrogenated amorphous silicon
heavily doped with n type impurity is formed on the semiconductor
pattern 40.
[0047] A data wire is formed on the ohmic contact layer pattern 55
and 56 and the gate insulating layer 30. The data wire includes a
conductive layer preferably made of conductive material with low
resistivity such as Al and Ag. The data wire includes a plurality
of data lines 62 extending substantially in a longitudinal
direction and intersecting the gate lines 22 to define pixel areas,
a plurality of source electrodes 65 connected to the data lines 62
and extending to one portions 55 of the ohmic contact layer
pattern, a plurality of data pads 68 connected to one ends of the
data lines 62 for receiving image signals from external devices,
and a plurality of drain electrodes 66 separated from the source
electrodes 65 and located on the other portions 56 of the ohmic
contact layer pattern opposite the source electrodes 65 with
respect to the gate electrodes 26.
[0048] A protective layer 70 preferably made of SiNx is formed on
the data wire 62, 65, 66 and 68 and portions of the semiconductor
pattern 40, which are not covered by the data wire 62, 65, 66 and
68, and an organic insulating layer 90 is formed on the protective
layer 70. The organic insulating layer 90 is preferably made of
photosensitive organic material having a good flatness
characteristic. The top surface of the organic layer 90 has an
evenness pattern to maximize the reflecting efficiency of a
reflecting film 86, which will be described later. At pad areas
with the gate pads 24 and the data pads 68, the organic insulating
layer 90 is removed out, while the protective layer 70 is still
remained. This structure removes organic insulating material on the
pad areas and thus is advantageously applicable to a chip on glass
("COG") type LCD, where a plurality of gate driving integrated
circuits ("ICs") and a plurality of data driving ICs for
respectively transmitting the scanning signals and the image
signals to the gate pads 24 and the data pads 68 are directly
mounted on the TFT array panel.
[0049] A plurality of contact holes 76 and 78 respectively exposing
the drain electrodes 66 and the data pads 68 are provided at the
protective layer 70, and a plurality of contact holes 74 exposing
the gate pads 24 are provided at the gate insulating layer 30 and
the organic insulating layers 90. The organic insulating layer 90
has a plurality of contact holes 96 exposing the drain electrodes
66, the boundaries of the contact holes 76 of the protective layer
70 exposing the drain electrodes 66, and the flat surface of the
protective layer 70.
[0050] A plurality of transparent electrodes 82 are folded on the
organic insulating layer 90. The transparent electrodes 82 are
located substantially in a pixel area, and electrically connected
to the drain electrodes 66 through the contact holes 76 and 96. A
reflecting film 86 having an aperture 85 is formed on each
transparent electrode 82. Among the pixel area P, an area T defined
by the aperture 85 is referred to as a transmitting area, while the
remaining area R is referred to as a reflecting area. The
transparent electrodes 82 are preferably made of transparent
conductive material such as indium zinc oxide ("IZO") and indium
tin oxide ("ITO"), while the reflecting films 86 are preferably
made of Al, Al alloy, Ag and Ag alloy having reflectance. Each
reflecting film 86 preferably includes a contact assistant layer
provided on a contact surface with the transparent electrode 82 to
ensure good contact characteristics between the reflecting film 86
and the transparent electrode 82, and the contact assistant layer
is preferably made of Mo, Mo alloy, Cr, Ti or Ta.
[0051] Furthermore, a plurality of subsidiary gate pads 84 and a
plurality of subsidiary data pads 88 are formed on the protective
layer 70. The subsidiary gate pads 84 and the subsidiary data pads
88 are connected to the gate and the data pads 24 and 68 through
the contact holes 74 and 78, respectively. Although the subsidiary
gate and data pads 84 and 88 are not requisites but preferred to
protect the gate and the data pads 24 and 68. The subsidiary gate
and data pads 84 and 88 are preferably made of the same layer
either as the transparent electrodes 82 or as the reflecting film
86.
[0052] A method of manufacturing a TFT array panel for a
transflective type LCD according to the first embodiment of the
present invention will be now described with reference to FIGS. 3A
to 8B as well as FIGS. 1 and 2.
[0053] As shown in FIGS. 3A and 3B, a conductive material with low
resistivity is deposited on a glass substrate 10, and patterned by
photo etch using a mask to form a gate wire extending substantially
in the transverse direction including a plurality of gate lines 22,
a plurality of gate electrodes 26, and a plurality of gate pads
24.
[0054] Next, as shown in FIGS. 4A and 4B, after sequentially
depositing three layers including a gate insulating layer 30 made
of SiNx, a semiconductor layer 40 made of amorphous silicon, and a
doped amorphous silicon layer 50, the doped amorphous silicon layer
50 and the semiconductor layer 40 are patterned by photo etch using
a mask to form a semiconductor pattern 40 and a doped amorphous
silicon layer pattern 50 on the gate insulating layer 30 opposite
the gate electrodes 24. At that time, the semiconductor pattern 40
may be formed along the data lines 62 which are described
later.
[0055] Subsequently, as shown in FIGS. 5A and 5B, a conductive
layer for a data wire is deposited and patterned by
photolithography using a mask to form a data wire including a
plurality of data lines 65 intersecting the gate lines 22, a
plurality of source electrodes 65 connected to the data lines 65
and extending onto the gate electrodes 26, a plurality of data pads
68 connected to one ends of the data lines 62, and a plurality of
drain electrodes 66 separated from the source electrodes 65 and
opposite the source electrodes 65 with respect to the gate
electrodes 26.
[0056] Thereafter, portions of the doped amorphous silicon pattern
50, which are not covered by the data wire 62, 65, 66 and 68, are
etched such that the doped amorphous silicon layer pattern 50 is
separated into two portions 55 and 56 opposite each other with
respect to the gate electrodes 26 to expose portions of the
semiconductor pattern 40 between the two portions of the doped
amorphous silicon layer pattern 55 and 56. Oxygen plasma treatment
is preferably performed in order to stabilize the exposed surfaces
of the semiconductor pattern 40.
[0057] As shown in FIGS. 6A and 6B, SiNx is deposited by CVD to
form a protective layer 70, and a photosensitive organic material
having a good flatness characteristic is coated on the protective
layer 70 to form an organic insulating layer 90 before patterning
the protective layer 70. Thus, the spin-coating of the organic
insulating layer 90 before patterning the protective layer 70
prevents the localized distribution of organic material onto a
specific area since there is no height difference due to the
protective layer 70 during the spin coating. Thereafter, the
organic insulating layer 90 is patterned by photolithography using
a mask to form a plurality of contact holes 96 exposing portions of
the protective layer 70 opposite the drain electrodes 66 and
simultaneously to form an unevenness pattern on the surface of the
organic insulating layer 90. Furthermore, portions of the organic
insulating layer 90 at the pad areas provided with the gate pads 24
and the data pads 68 are removed to expose the protective layer
70.
[0058] Subsequently, as shown in FIG. 7, a plasma process using Ar
gas is executed to enhance surface roughness of the organic
insulating layer 90 before patterning the protective layer 70.
Here, Ar gas may be replaced with inactive gas such as N2, He, Ne,
Kr and Xe. The surface roughness of the organic insulating layer 90
is enhanced by the plasma process to improve the adhesiveness of an
ITO film 82 which will be described later. According to an
embodiment of the present invention, since the plasma process is
executed before patterning the protective layer 70, the gate lines
or the data lines which may be exposed later on a contact are not
injured.
[0059] Subsequently, as shown in FIGS. 8A and 8B, the protective
layer 70 and the gate insulating layer 30 are patterned by photo
etch using a photoresist pattern 1000 to form a plurality of
contact holes 74, 76 and 78 exposing the gate pads 24, the drain
electrodes 66, and the data pads 68, respectively. The contact
holes 76 of the protective layer 70 exposing the drain electrodes
66 are placed inside the contact holes 96 of the organic insulating
layer 90 such that the boundaries and the flat surfaces of the
protective layer 70 are exposed, and therefore the contact
structures have stepwise shapes without undercut. It is preferable
that the width of the exposed surface of the protective layer 70 at
the contact structure is 0.1 microns or more.
[0060] When the data wire 62, 65, 66 and 68 or the gate wire 22, 24
and 26 have multiple layers and the top layer of the data wire 62,
65, 66 and 68 or the gate wire 22, 24 and 26 is formed of Al or Al
alloy, the top layer is removed to prevent the top layer of Al or
Al alloy from contacting an ITO film, which will be formed later,
at a contact.
[0061] Next, as shown in FIGS. 9A and 9B, ITO is deposited and
patterned using a mask to form a plurality of transparent
electrodes 82 connected to the drain electrodes 66 through the
contact holes 76 and 96, a plurality of subsidiary gate pads 84
connected to the gate pads 24 through the contact holes 74, and a
plurality of subsidiary data pads 88 connected to the data pads 68
through the contact holes 78.
[0062] A manufacturing method of a TFT array panel according to the
first embodiment of the present invention prevents the wires from
being damaged at a contact by performing plasma process before the
protective layer 70 is removed at the contact, as described above.
In addition, organic insulating material remaining inside the
contact holes 76, 96, 74 and 78 is completely removed by performing
plasma process for surface-treating the organic insulating layer 90
before patterning the protective layer 70 by photo etch for forming
the contact holes 74, 76 and 78 at the protective layer 70.
Therefore, contact resistance at a contact is minimized and
inactive gas which may be remained during the plasma process is
completely removed.
[0063] Finally, as shown in FIGS. 1 and 2, a reflective conductive
material including Ag or Al with reflectance is deposited and
patterned by photo etch using a mask to form a plurality of
reflecting films 86 on the respective transparent electrodes 82. At
this time, each reflecting film 86 preferably includes a contact
assistant layer made of material having a good contact
characteristic with other materials to improve the contact
characteristic with the transparent electrode 82.
[0064] According to the first embodiment of the present invention,
the spin-coating of the organic insulating layer 90 before
patterning the protective layer 70 prevents the localized
distribution of organic material onto a specific area since there
is no height difference due to the protective layer 70 during the
spin coating, thereby obtaining a uniform unevenness pattern on the
organic insulating layer 90. As a result, the embossment of the
reflecting film 86 following the unevenness pattern of the organic
insulating layer 90 is established to be uniform, and this prevents
stains on a screen displaying images.
[0065] The method of manufacturing a TFT array panel according to
this embodiment of the present invention completely prevents
organic insulating material from remaining on the pad areas because
the protective layer 70 is patterned after removing the organic
insulating material from the pad areas in the formation of the
organic insulating layer 90. Therefore, the TFT array panel
manufactured by this method is advantageously applicable
particularly to a COG type LCD, where a plurality of gate driving
ICs and a plurality of data driving ICs for respectively
transmitting the scanning signals and the image signals to the gate
pads 24 and the data pads 68 are directly mounted on the TFT array
panel. In the meantime, the manufacturing method according to the
first embodiment of the present invention can be adapted to a
method for manufacturing a TFT array panel for a reflective type
LCD.
[0066] A TFT array panel for a reflective type LCD according to a
second embodiment of the present invention will be described in
detail with reference to FIGS. 10 and 11.
[0067] As shown in FIGS. 10 and 11, the structure is almost the
same as the structure according to the first embodiment.
[0068] However, different from the first embodiment, a plurality of
reflecting films 86 are located directly on an organic insulating
layer 90 and in direct electrical connection with a plurality of
drain electrodes 66 through a plurality of contact holes 76 and 96.
In addition, the reflecting film 86 occupies the entire pixel
area.
[0069] Moreover, a plurality of gate wire 22, 24 and 26 and a
plurality of data wire 62, 65 and 66 overlap relevant pixel
electrodes 82 via the organic insulating layer 90 with low
dielectric constant to give maximum aperture ratio.
[0070] Furthermore, a data wire 62, 65, 66 and 68 includes a
conductor pattern 64 for storage capacitors overlapping the gate
lines 22, and the pixel electrodes 82 made of a transparent
conductive material are placed directly on an organic insulating
layer 90. The pixel electrodes are located substantially in pixel
areas and electrically connected to a plurality of drain electrode
66 through contact holes 76 and 96. The pixel electrodes 82 are
electrically connected to the conductor pattern 64 through contact
holes 72 and 92 provided at the protective layer 70 and the organic
insulating layer 90, and contact holes 74 provided at the
protective layer 70 and a gate insulating layer 30 exposing gate
pads 24 are wider than the gate pads 24.
[0071] A method of manufacturing a TFT array panel for a
transmissive type LCD according to the second embodiment of the
present invention is almost the same as the method according to the
first embodiment, until the step of forming contact holes 72, 74,
76 and 78 at a protective layer 70.
[0072] The method of manufacturing the TFT array panel according to
the second embodiment of the present invention provides a
semiconductor layer 40 extending in the longitudinal direction
along the data wire 62, 65, 66 and 68, and does not form an
unevenness pattern on the surface of an organic insulating layer
90.
[0073] The above-described manufacturing method according to the
embodiments of the present invention can be applied to a method of
manufacturing a TFT array panel for a transmissive type LCD forming
both a semiconductor layer and a data wire by photo etch using one
photoresist pattern, thereby simplifying the manufacturing process.
This method will be described in detail with reference to
accompanying drawings.
[0074] First, a structure of a unit pixel of a TAT array panel for
an LCD manufactured using four masks according to an embodiment of
the present invention will be described with reference to FIGS. 12
to 14.
[0075] FIG. 12 is a layout view of a TFT array panel for an LCD
according to a fourth embodiment of the present invention, and
FIGS. 13 and 14 are sectional views of the TFT array panel shown in
FIG. 12 taken along the line XIII-XIII' and the line XIV-XIV' of
FIG. 12, respectively.
[0076] As in the second embodiment, a gate wire is formed on an
insulating substrate 10. The gate wire is preferably made of a
material with low resistivity such as Ag, Ag alloy, Al and Al
alloy. The gate wire includes a plurality of gate lines 22, a
plurality of gate pads 24, and a plurality of gate electrodes 26.
The gate wire further includes a plurality of storage electrodes 28
formed on the substrate, which are substantially parallel to the
gate lines 22 and applied with a predetermined voltage such as a
common voltage from an external source, which is also applied to a
common electrode of an upper panel. The storage electrodes 28
overlap a storage capacitor conductor pattern connected to pixel
electrodes 82, which will be described later, to form storage
capacitors for improving the charge storing capacity of pixels. The
storage electrodes 28 may be omitted if the storage capacitance due
to the overlapping of the gate lines 22- and the pixel electrodes
82 to be described later are sufficient.
[0077] A gate insulating layer 30 preferably made of silicon
nitride is formed on the gate wire 22,24,26 and 28, while covering
the gate wire 22,24,26 and 28.
[0078] A semiconductor pattern 42 and 48 preferably made of
hydrogenated amorphous silicon is formed on the gate insulating
layer 30, and an ohmic contact layer pattern or an intermediate
layer pattern 55, 56 and 58 preferably made of amorphous silicon
heavily doped with n type impurity such as phosphorous is formed on
the semiconductor layer 42 and 48.
[0079] A data wire made of an aluminum-based conductive material
with low resistivity is formed on the ohmic contact layer pattern
55, 56 and 58. The data wire includes a plurality of data portions
62, 65 and 68, a plurality of drain electrodes 66 of TFTs, and a
storage capacitor conductor pattern 64. Each data portion includes
a data line 62 extending substantially in the longitudinal
direction, a data pad 68 connected to one end of the data line 62
for receiving image signals from an external device, and a
plurality of source electrodes 65 branched from the data line 62.
Each drain electrode 66 is separated from the data portion 62, 65
and 68, and placed opposite the corresponding source electrode 53
with respect to the corresponding gate electrode 26 or a channel
portion of the associated TFT. The storage capacitor conductor
pattern 64 is placed on the storage electrodes 28. In absence of
the storage electrodes 28, the storage capacitor conductor pattern
64 is not provided.
[0080] The ohmic contact layer pattern 55, 56 and 58 plays a role
of reducing the contact resistance between the semiconductor
pattern 42 and 48 thereunder and the data wire 62, 64, 65, 66 and
68 thereover. The ohmic contact layer pattern 55, 56 and 58 has
substantially the same shape as the data wire 62, 64, 65, 66 and
68. In detail, a data intermediate layer pattern 55 of the have
substantially the same shapes as the data portions 62, 65 and 68, a
drain intermediate layer pattern 56 as the drain electrodes 66, and
a storage capacitor intermediate layer pattern 58 as the storage
capacitor conductor pattern 68.
[0081] The semiconductor pattern 42 and 48 has the same shape as
the data wire 62, 64, 65, 66 and 68 and the ohmic contact layer
pattern 55, 56 and 58 except for the channel areas C of the TFTs.
Specifically, a storage capacitor semiconductor pattern 48 has
substantially the same shape as the storage capacitor conductor
pattern 64 and the storage capacitor ohmic contact layer pattern
58, while a TFT semiconductor pattern 42 layer is a little
different from the data wire and the rest of the ohmic contact
layer pattern. On the channel areas C of each TFT, although the
data portions 62, 65 and 68, especially the source electrodes 65
are separated from the drain electrodes 66, and the data
intermediate layer pattern 55 is also separated from the drain
ohmic contact layer pattern 56, the TFT semiconductor pattern 42 is
not disconnected to form channels of the TFTs.
[0082] An interlayer insulator including a protective layer 70
preferably made of silicon nitride and an organic insulating layer
90 preferably made of organic insulating material with low
permittivity is provided on the data wire 62, 65, 66 and 68 as in
the first embodiment. The protective layer 70 has a plurality of
contact holes 76, 78 and 72 exposing the drain electrodes 66, the
data pads 68, and the storage capacitor conductor pattern 64,
respectively, and a plurality of contact holes 74 exposing the gate
pads 24 together with the gate insulating layer 30. Like the first
embodiment, the organic insulating layer 90 is removed out from the
pad areas to expose the protective layer 70, and the contact holes
92 and 96 expose the boundaries of the protective layer 70, which
is a lower insulating layer, such that the sidewalls of the contact
holes 72, 92; and 76, 96 have stepwise shapes.
[0083] A plurality of pixel electrodes 82 receiving image signals
from the TFTs and generating electric fields in cooperation with an
electrode on an upper panel are formed on the organic insulating
layer 90. The pixel electrodes 82 are made of transparent
conductive material such as IZO or ITO, and electrically connected
to the drain electrodes 66 through the contact holes 76 and 96 to
receive image signals. Furthermore, the pixel electrodes 82 overlap
the adjacent gate lines 22 and the adjacent data lines 62 to
increase the aperture ratio. However, the overlaps may be omitted.
The pixel electrodes 82 are connected to the storage capacitor
conductor pattern 64 through the contact holes 72 and 92 to
transmit the image signals.
[0084] A plurality of subsidiary gate pads 84 and a plurality of
subsidiary data pads 88 are formed on the protective layer 70. The
subsidiary gate pads 84 and the subsidiary data pads 88 are located
on the gate pads 24 and the data pads 24 and 68, respectively, and
thus connected thereto through the contact holes 74 and 78,
respectively. Although the subsidiary gate pads 84 and the
subsidiary data pads 88 are not requisites but preferred to protect
the pads 24 and 68 and to complement the adhesiveness between the
pads 24 and 68 and external circuit devices. The contact structure
has no undercut and thus prevents the disconnections of the pixel
electrodes 82, the subsidiary gate pads 84, and the subsidiary data
pads 88. The subsidiary gate pads 84 and the subsidiary data pads
88 are located on the protective layer 70 at least in part.
[0085] Now, a method of manufacturing a TFT array panel for an LCD
having the structure shown in FIGS. 12-14 using four masks will be
described in detail with reference to FIGS. 12-14 and FIGS.
15A-22C.
[0086] First, as shown in FIGS. 15A-15C, a gate wire including a
plurality of gate lines 22, a plurality of gate pads 24, a
plurality of gate electrodes 26, and a plurality of storage
electrodes 28 is formed on a substrate 10 by depositing a
conductive material or materials for the gate wire and patterning
by photo etch using a first mask. The gate wire has a
single-layered structure including a single layer made of material
with low resistivity such as Al, Al alloy, Ag or Ag alloy.
Alternatively, the conductive layer has a multiple-layered
structure including the single layer and a layer made of conductive
material with good contact characteristics with other materials,
such as Cr, Ti, and Ta.
[0087] Next, as shown in FIGS. 16A and 16B, a gate insulating layer
30, a semiconductor layer 40, and an intermediate layer 50 are
sequentially deposited by CVD such that the layers 30, 40 and 50
bear thickness of 1,500-5,000 .ANG., 500-2,000 .ANG. and 300-600
.ANG., respectively. A conductive layer 60 for a data wire with low
resistivity is deposited by sputtering such that the layer 60 bears
the thickness of 1,500-3,000 .ANG., and subsequently a photoresist
film 110 with the thickness of 1-2 microns is coated on the
conductive layer 60.
[0088] Subsequently, the photoresist film 110 is exposed to light
through a second mask, and developed to form a photoresist pattern
114 and 112 as shown in FIGS. 17A-17C. First portions 114 of the
photoresist pattern 114 and 112, which are located on channel areas
C of TFTs between source and drain electrodes 65 and 66, are
established to bear thickness smaller than that of the second
portions 112 on data areas A where the data wire 62, 64, 65, 66 and
68 is formed. The portions of the photoresist film on the remaining
area B are removed. The thickness ratio of the first portions 114
on the channel areas C to the second portions 112 on the data areas
A is adjusted depending upon the etching conditions in the etching
steps to be described later. It is preferable that the thickness of
the first portions 114 is equal to or less than half of the
thickness of the second portions 112, in particular, equal to or
less than 4,000 .ANG..
[0089] The position-dependent thickness of the photoresist film is
obtained by several techniques. In order to adjust the amount of
light exposure in the areas C, semi-transparent areas having a slit
pattern, a lattice pattern or semi-transparent films are provided
on a mask.
[0090] When using a slit pattern, it is preferable that the width
of the portions between the slits or the distance between the
portions, i.e., the width of the slits is smaller than the
resolution of an exposer used for the photolithography. In case of
using semi-transparent films, thin films with different
transmittances or with different thicknesses may be used to adjust
the transmittance of the mask.
[0091] When the photoreceptive film is irradiated with light
through such a mask, polymers of the portions directly exposed to
the light are almost completely decomposed, and those of the
portions facing the slit pattern or the semi-transparent films are
not completely decomposed due to the small amount of light
exposure. The polymers of the portions blocked by light-blocking
films are hardly decomposed. Development of the photoreceptive film
makes the portions having the polymers, which are not decomposed,
to be left, and makes the portions exposed to the smaller light
irradiation to be thinner than the portions which do not experience
the light exposure. Here, it is required not to make the exposure
time long enough to decompose all the molecules.
[0092] The thin portions 114 of the photoresist pattern may be
obtained by performing a reflow process to flow a reflowable
photoresist film into the areas without the photoresist film after
exposing to light and developing the photoresist film, using a
usual mask with transmissive areas completely transmitting the
light and blocking areas completely blocking the light.
[0093] Thereafter, the photoresist pattern 114 and the underlying
layers, i.e., the conductive layer 60, the intermediate layer 50
and the semiconductor layer 40 are etched such that a data wire and
the underlying layers are left over on the data areas A, only the
semiconductor layer is left over on the channel areas C, and all of
the three layers 60, 50 and 40 are removed from the remaining areas
B to expose the gate insulating layer 30.
[0094] As shown in FIGS. 18A and 18B, the exposed portions of the
conductive layer 60 on the areas B are removed to expose the
underlying portions of the intermediate layer 50. In this step,
both dry etching and wet etching is selectively used and preferably
performed under the condition that the conductive layer 60 is
selectively etched while the photoresist pattern 112 and 114 is
hardly etched. However, an etching condition capable of etching the
photoresist pattern 112 and 114 as well as the conductive layer 60
would be suitable for dry etching since it is difficult to find a
condition for selectively etching only the conductive layer 60
while not etching the photoresist pattern 112 and 114. In this
case, the first portion 114 should have relatively thick compared
with that for wet etching in order to prevent the exposure of the
underlying conductive layer 60 through the etching.
[0095] Both dry etching and wet etching are applicable to the
conductive material for a data wire containing Al or Al alloy. Wet
etching, preferably with an etchant CeNHO3, is preferred for Cr
which is hardly removed by dry etching. However, a very thin Cr
film of about 500 .ANG. may be removed by dry etching.
[0096] Consequently, as shown in FIGS. 18A and 18B, a source/drain
conductor pattern 67, i.e., portions of the conductive layer on the
channel areas C and the data areas A, and a storage capacitor
conductor pattern 64 are left over, while portions of the
conductive layer 60 on the remaining areas B is removed out to
expose the underlying portions of the intermediate layer 50. The
remaining conductor patterns 67 and 64 have substantially the same
shapes as the data wire 62, 64, 65, 66 and 68 except that the
source and the drain electrodes 65 and 66 are still connected
without separation. When using the dry etching, the photoresist
pattern 112 and 114 are also etched to a predetermined
thickness.
[0097] Next, as shown in FIGS. 19A and 19B, the exposed portions of
the intermediate layer 50 on the areas B and the underlying
portions of the semiconductor layer 40 are simultaneously removed
by dry etching together with the first portions 114 of the
photoresist pattern. Sequential dry etch of the intermediate layer
50 and the semiconductor layer 40 may follow the dry etch of the
conductor patterns 64 and 67 or in-situ etch process may be
performed. The etch of the intermediate layer 50 and the
semiconductor layer 40 is preferably made in a condition that the
photoresist pattern 112 and 114, the intermediate layer 50 and the
semiconductor layer 40 are simultaneously etched while the gate
insulating layer 30 is not etched. (It is noted that the
semiconductor layer and the intermediate layer have no etching
selectivity.) Particularly, the etching ratios of the photoresist
pattern 112 and 114 and the semiconductor layer 40 are preferably
equal to each other. For the equal etching ratios of the
photoresist pattern 112 and 114 and the semiconductor layer 40, the
thickness of the first portions 114 is preferably equal to or less
than the sum of the thicknesses of the semiconductor layer 40 and
the intermediate layer 50.
[0098] In this way, as shown in FIGS. 19A and 19B, the portions of
the conductive layer 60 on the channel areas C and the data areas
A, i.e., the source/drain conductor pattern 67 and the storage
capacitor conductor pattern 64 are left over, while the portions of
the conductive layer 60 on the remaining areas B are removed out.
Moreover, the first portions 114 on the channel areas C are removed
to expose the source/drain conductor pattern 67, and the portions
of the intermediate layer 50 and the semiconductor layer 40 on the
areas B are removed to expose the underlying portions of the gate
insulating layer 30. Meanwhile, the second portions 112 on the data
areas A are also etched to have reduced thickness. In this step,
the formation of a semiconductor pattern 42 and 48 are completed.
Reference numerals 57 and 58 indicate intermediate layer patterns
under the source/drain conductor pattern 67 and under the storage
capacitor conductor pattern 64, respectively. The exposure of the
portions of the source/drain conductor pattern 67 on the channel
areas C is alternatively obtained by a separate photoresist ("PR")
etch back step, which is not necessary under the condition that the
photoresist film is sufficiently etched.
[0099] Residual photoresist remained on the surface of the
source/drain conductor pattern 67 on the channel areas C is then
removed by ashing.
[0100] Subsequently, as shown in FIGS. 20A and 20B, the exposed
portions of the source/drain conductor pattern 67 on the channel
areas C and the underlying portions of the source/drain
intermediate layer pattern 57 are etched to be removed. Dry etching
may be applied to both of the source/drain conductor pattern 67 and
the source/drain intermediate layer pattern 57. Alternatively, wet
etching is applied to the source/drain conductor pattern 67 while
dry etching is applied to the source/drain intermediate layer
pattern 57. At this time, as shown in FIG. 15B, top portions of the
semiconductor pattern 42 may be removed to cause thickness
reduction, and the second portions 112 of the photoresist pattern
is etched to a predetermined thickness. The etching is performed
under the condition that the gate insulating layer 30 is hardly
etched, and it is preferable that the photoresist film is so thick
to prevent the second portion 112 from being etched to expose the
underlying data wire 62, 64, 65, 66 and 68.
[0101] In this way, the source and the drain electrodes 65 and 66
are separated from each other while completing the formation of the
data wire 62, 64, 65, 66 and 68 and the underlying ohmic contact
layer pattern 55, 56 and 58.
[0102] Finally, the second portions 112 remained on the data areas
A are removed. However, the removal of the second portions 112 may
be made between the removal of the portions of the source/drain
conductor pattern 67 on the channel areas C and the removal of the
underlying portions of the intermediate layer pattern 57.
[0103] After the data wire 62, 64, 65, 66 and 68 is formed as
described above, silicon nitride is deposited by CVD to form a
protective layer 70 as shown in FIGS. 21A-21C. An organic
insulating layer 90 is formed on the protective layer 70 by
spin-coating photosensitive organic material having a good flatness
characteristic and low permittivity before patterning the
protective layer 70. The spin-coating of the organic insulating
layer 90 before patterning the protective layer 70 according to
this embodiment of the present invention prevents the localized
distribution of the organic insulating layer 90 onto a specific
area because there is no height difference due to the protective
layer 70 during the spin coating. Thereafter, the organic
insulating layer 90 is patterned by photolithography using a mask
to form a plurality of contact holes 96 and 92 exposing portions of
the protective layer 70 on the drain electrodes 66 and the storage
capacitor conductor pattern 64. At this time, the portions the
organic insulating layer 90 at the pad areas with the gate pads 24
or the data pads 68 are removed to expose the protective layer
70.
[0104] Subsequently, as shown in FIGS. 21B and 21C, the plasma
process using inactive gas such as Ar is performed to enhance the
surface roughness of the organic insulating layer 90. As a result,
a contact area between the pixel electrode 82, which will be formed
later, and the organic insulating layer 90 is increased to ensure
the adhesiveness therebetween. The plasma process performed before
patterning the protective layer 70 may prevent the organic material
from remaining directly on the signal wires 66, 64, 24 and 68.
[0105] Referring to FIGS. 22A to 22C, as in the first embodiment,
the protective layer 70 as well as the gate insulating layer 30 is
patterned by photo etch using a photoresist pattern to form a
plurality of contact holes 74, 76, 72 and 78 exposing the gate pads
24, the drain electrodes 66, the storage capacitor conductor
pattern 64 and the data pads 68, respectively. The contact holes 76
and 72 of the protective layer 70 exposing the drain electrodes 66
and the storage capacitor conductor pattern 64 are placed inside
the contact holes 96 and 92 of the organic insulating layer 90.
[0106] According to manufacturing methods of the embodiments of the
present invention, although the organic material is re-deposited to
remain on the exposed portions of the protective layer 70 by the
previous plasma process, the organic material remnants at contacts
including the contact holes 74, 76, 72 and 78 is almost removed in
the pattering step of the protective layer 70 for forming the
contact holes 74, 76, 72 and 78. Furthermore, since the protective
layer 90 is patterned after performing the plasma process,
remaining gas used in the plasma process is almost removed.
[0107] When the data wire 62, 64, 65, 66 and 68 or the gate wire
22,24, 26 and 28 have multiple layers and the top layer of the data
wire 62, 65, 66 and 68 or the gate wire 22, 24 and 26 is formed of
Al or Al alloy, the top layer is removed to prevent the top layer
of Al or Al alloy from contacting an ITO film, which will be formed
later, at a contact.
[0108] Finally, after removing the photoresist pattern, as shown in
FIGS. 12 to 14 like the first and the second embodiments of the
present invention, ITO or IZO with a thickness of 400-500 .ANG. is
deposited and etched using a fourth mask to form a plurality of
pixel electrodes 82 connected to the drain electrodes 66 and the
storage capacitor conductor pattern 64, a plurality of subsidiary
gate pads 84 connected to the gate pads 24, and a plurality of
subsidiary data pads 84 and 88 connected to the data pads 68.
[0109] The third embodiment of the present invention provides not
only the advantages according to the first embodiment ensuring the
adhesiveness between the organic insulating layer 90 and the pixel
electrode 82 and minimizing the contact resistance at a contact but
also a simplified process that the data wire 62, 64, 65, 66 and 68,
the ohmic contact layer pattern 55, 56 and 58 and the semiconductor
pattern 42 and 48 thereunder are formed using one mask, and
simultaneously, the source and the drain electrodes 65 and 66 are
separated from each other in this step.
[0110] The connection between driving ICs and pads of a TFT array
panel for an LCD manufactured by these methods is implemented by
using TCPs with driving ICs mounted on respective films or by means
of the COP style. Alternatively, the electrical connection
therebetween is obtained by means of the above described COG style
which directly mounts driving ICs on a panel.
[0111] Although the first to third embodiments of the present
invention illustrate manufacturing methods of TFT array panels
having semiconductor patterns made of amorphous silicon, the
present invention may be applied to a manufacturing method of a TFT
array panel having the semiconductor pattern made of
polysilicon.
[0112] In this way, under the condition that a wire is covered with
a protective layer, the surface of an organic insulating layer is
treated by the plasma process and then the protective layer is
patterned to form a contact exposing the wire. Therefore, it
prevents the gases for the plasma process or organic materials from
being remained at the contact. Accordingly, the present invention
ensures the adhesiveness between the organic insulating layer and
the pixel electrode and minimizes the contact resistance at a
contact.
* * * * *