U.S. patent application number 11/870806 was filed with the patent office on 2008-04-17 for method for forming a metal line and method for manufacturing display substrate having the metal line.
Invention is credited to Hong-Kee Chin, Seung-Ha Choi, Shin-II Choi, Yu-Gwang Jeong, Sang-Gab Kim, Min-Seok OH.
Application Number | 20080087633 11/870806 |
Document ID | / |
Family ID | 39302211 |
Filed Date | 2008-04-17 |
United States Patent
Application |
20080087633 |
Kind Code |
A1 |
OH; Min-Seok ; et
al. |
April 17, 2008 |
METHOD FOR FORMING A METAL LINE AND METHOD FOR MANUFACTURING
DISPLAY SUBSTRATE HAVING THE METAL LINE
Abstract
A method for forming a metal line includes sequentially
depositing a low-resistivity metal layer having aluminum on a base
substrate and an upper layer having molybdenum on the
low-resistivity metal layer, forming a photoresist pattern having a
linear shape on the upper layer, etching the upper layer via a
mixed gas using the photoresist pattern as a mask, the mixed gas
including a chlorine based gas mixed with an additional gas having
at least one of nitrogen gas, argon gas, helium gas and sulfur
hexafluoride gas, and etching the low-resistivity metal layer using
the photoresist pattern as the mask thereby removing any stringer
that may be caused by a residue of the low-resistivity metal
layer.
Inventors: |
OH; Min-Seok; (Gyeonggi-do,
KR) ; Kim; Sang-Gab; (Seoul, KR) ; Jeong;
Yu-Gwang; (Gyeonggi-do, KR) ; Choi; Seung-Ha;
(Gyeonggi-do, KR) ; Chin; Hong-Kee; (Gyeonggi-do,
KR) ; Choi; Shin-II; (Gyeonggi-do, KR) |
Correspondence
Address: |
MACPHERSON KWOK CHEN & HEID LLP
2033 GATEWAY PLACE, SUITE 400
SAN JOSE
CA
95110
US
|
Family ID: |
39302211 |
Appl. No.: |
11/870806 |
Filed: |
October 11, 2007 |
Current U.S.
Class: |
216/41 ; 216/74;
257/E29.147; 257/E29.151 |
Current CPC
Class: |
G02F 1/136295 20210101;
H01L 21/32136 20130101; H01L 27/124 20130101; H01L 29/458 20130101;
C23F 1/12 20130101; H01L 27/1288 20130101; G02F 1/13629 20210101;
H01L 29/4908 20130101 |
Class at
Publication: |
216/41 ;
216/74 |
International
Class: |
C23F 1/12 20060101
C23F001/12 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 12, 2006 |
KR |
10-2006-0099184 |
Claims
1. A method for forming a metal line, the method comprising:
sequentially depositing a low-resistivity metal layer having
aluminum on a base substrate, and an upper layer having molybdenum
on the low-resistivity metal layer; forming a photoresist pattern
having a linear shape on the upper layer; etching the upper layer
via a mixed gas using the photoresist pattern as a mask, the mixed
gas including a chlorine based gas mixed with an additional gas
having at least one selected from the group consisting of nitrogen
gas, argon gas, helium gas and sulfur hexafluoride gas; and etching
the low-resistivity metal layer using the photoresist pattern as
the mask.
2. The method of claim 1, wherein a ratio of the additional gas
with respect to the chlorine based gas is between about 50% and
about 200%.
3. The method of claim 2, wherein the upper layer is etched with
conditions that a source power density [W/cm.sup.2] is between
about 1 and about 2, and a bias power density [W/cm.sup.2] is
between about 0.3 and about 0.6.
4. The method of claim 1, wherein the low-resistivity metal layer
is etched by the mixed gas including the chlorine based gas mixed
with the argon gas or the nitrogen gas.
5. The method of claim 4, wherein a ratio of the argon or nitrogen
gas with respect to the chlorine based gas is between about 50% and
about 150%.
6. The method of claim 5, wherein the low-resistivity metal layer
is etched with conditions that a source power density [W/cm.sup.2]
is between about 0.7 and about 1.8, and a bias power density
[W/cm.sup.2] is between about 0.7 and about 1.8.
7. The method of claim 1, further comprising removing a corrosive
element remaining on the base substrate after etching the
low-resistivity metal layer.
8. The method of claim 7, further comprising forming a lower layer
including the molybdenum under the low-resistivity metal layer.
9. The method of claim 8, further comprising etching the lower
layer using the mixed gas including the chlorine based gas mixed
with the additional gas having at least one selected from the group
consisting of nitrogen gas, argon gas, helium gas and sulfur
hexafluoride gas, before removing the corrosive element.
10. The method of claim 7, wherein the corrosive element is removed
by using at least one selected from the group consisting of
H.sub.20 gas and H.sub.2 gas.
11. The method of claim 7, wherein the corrosive element is removed
by using a fluorine (F) based gas.
12. The method for manufacturing a display substrate, the method
comprising: forming a gate insulating layer on a base substrate, a
gate pattern having a gate line and a gate electrode formed on the
base substrate; sequentially forming a source metal layer including
a lower layer, a low-resistivity layer and an upper layer, the
lower layer having molybdenum formed on the gate insulating layer,
the low-resistivity metal layer having aluminum formed on the lower
layer, the upper layer having molybdenum formed on the
low-resistivity metal layer; forming a source pattern having a
source line, a source electrode and a drain electrode by etching
the upper layer using a chlorine based gas mixed with an additional
gas having at least one selected from the group consisting of
nitrogen gas, argon gas, helium gas and sulfur hexafluoride gas;
forming a protective insulating layer having a contact hole formed
in the protective insulating layer, the contact hole partially
exposing the drain electrode; and forming a pixel electrode
electrically connected to the drain electrode through the contact
hole.
13. The method of claim 12, wherein a ratio of the additional gas
with respect to the chlorine based gas is between about 50% and
about 200%.
14. The method of clam 13, wherein the upper layer is etched with
conditions that a source power density [W/cm.sup.2] is between
about 1 and about 2, and a bias power density [W/cm.sup.2] is
between about 0.3 and about 0.6.
15. The method of claim 14, wherein forming the source pattern
comprises: forming an electrode pattern and the source line, via
etching the source metal layer; etching an upper layer of the
electrode pattern using the chlorine based gas mixed with the
additional gas having at least one selected from the group
consisting of nitrogen gas, argon gas, helium gas and sulfur
hexafluoride gas; etching a low-resistivity metal layer of the
electrode pattern using the mixed gas including the chlorine based
gas mixed with argon gas or nitrogen gas; and etching a lower layer
of the electrode pattern using the chlorine based gas mixed with
the additional gas having at least one selected from the group
consisting of nitrogen gas, argon gas, helium gas, and sulfur
hexafluoride gas.
16. The method of claim 15, wherein the low-resistivity metal layer
is etched with conditions that a chamber pressure is between about
10 and about 30, the source power density [W/cm.sup.2] is between
about 0.7 and about 1.8, and the bias power density [W/cm.sup.2] is
between about 0.7 and about 1.8.
17. The method of claim 14, wherein forming the source pattern
comprises: etching an upper layer of the source metal layer using
chlorine based gas mixed with the additional gas having at least
one selected from the group consisting of nitrogen gas, argon gas,
helium gas and sulfur hexafluoride gas; etching a low-resistivity
metal layer of the source metal layer using the chlorine based gas
mixed with argon gas or nitrogen gas; and forming the source line,
the source electrode and the drain electrode by etching a lower
layer of the source metal layer using the chlorine based gas mixed
with the additional gas having at least one selected from the group
consisting of nitrogen gas, argon gas, helium gas and sulfur
hexafluoride gas.
18. The method of claim 12, further comprising removing a corrosive
element corroding the low-resistivity metal layer, after forming
the source pattern.
19. The method of claim 18, wherein the corrosive element is
removed by using at least one selected from the group consisting of
H.sub.20 gas and H.sub.2 gas.
20. The method of claim 18, wherein the corrosive element is
removed by using a fluorine (F) based gas.
Description
REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 U.S.C. .sctn. 119
to Korean Patent Application No. 2006-99184, filed on Oct. 12,
2006, in the Korean Intellectual Property Office (KIPO), the
contents of which in its entirety are herein incorporated by
reference in their entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a method of manufacturing a
display substrate and, more particularly, to a method of
manufacturing a display substrate having a metal line exhibiting
reduced resistance.
[0004] 2. Description of the Related Art
[0005] Generally, a liquid crystal display ("LCD") apparatus
includes a display substrate, a counter substrate, and a liquid
crystal layer disposed between the display substrate and the
counter substrate. Gate lines and source lines whose longitudinal
directions cross each other are formed on the display substrate. A
switching element, electrically connected to the gate and source
lines and a pixel electrode, electrically connected to the
switching element, are formed on the display substrate.
[0006] As display apparatus have become larger the RC delay of the
metal layer formed on the display substrate has increased. To
minimize the RC delay, the metal layer is formed by using aluminum
having a low resistance. However, many defects may be generated in
manufacturing an aluminum metal layer which also tends to exhibit a
high contact resistance with other layers.
[0007] Thus, a double layer structure or a triple layer structure
having a low resistivity metal layer is employed that may include
an aluminum (Al) layer and a molybdenum (Mo) layer while the triple
layer structure may include a first molybdenum (Mo) layer, an
aluminum (Al) layer and a second molybdenum (Mo) layer.
[0008] In order to form the low resistivity metal layer structure,
the molybdenum layer is etched by using a chlorine based gas mixed
with oxygen gas. Because the chlorine based gas mixed with oxygen
has high reactivity, contamination may be a problem. In addition,
the mixed gas reacts with aluminum forming an undesired aluminum
oxide layer allowing a stringer of the aluminum layer to remain at
the edge of a pattern.
SUMMARY OF THE INVENTION
[0009] According to an aspect of the present invention a display
substrate having an accurately formed metal layer of low resistance
is made by depositing, on a base substrate, a low resistivity
aluminum layer and then sequentially depositing an upper layer
having molybdenum on the low resistivity metal layer. A photoresist
pattern having a linear shape is formed on the upper layer. The
upper layer is etched using a mixed gas with the photoresist
pattern as a mask. The low resistivity metal layer is etched using
the photoresist pattern as the mask. The mixed gas includes a
chlorine based gas mixed with an additional gas having at least one
of nitrogen gas, argon gas, helium gas and sulfur hexafluoride
gas.
[0010] In an exemplary method for manufacturing the display
substrate according to the present invention, a gate insulating
layer is formed on a base substrate, and a gate pattern having a
gate line and a gate electrode is formed on the base substrate. A
source metal layer is formed by sequentially forming a lower layer,
a low-resistivity layer, and an upper layer on the gate insulating
layer. A source pattern having a source line, a source electrode
and a drain electrode, is formed by etching the upper layer using a
mixed gas including a chlorine based gas mixed with an additional
gas having at least one of nitrogen gas, argon gas, helium gas and
sulfur hexafluoride gas. A protective insulating layer having a
contact hole is formed in the protective insulating layer. A pixel
electrode electrically connected to the drain electrode through the
contact hole is formed. The lower layer has molybdenum formed on
the gate insulating layer. The low-resistivity metal layer has
aluminum formed on the lower layer. The upper layer has molybdenum
formed on the low-resistivity metal layer. The contact hole
partially exposes the drain electrode.
[0011] According to the present invention, etching of the
molybdenum layer formed on the aluminum layer is performed so that
a stringer that the aluminum layer includes may be removed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The above and other features and advantages of the present
invention will become more apparent by describing in detailed
example embodiments thereof with reference to the accompanying
drawings, in which:
[0013] FIGS. 1A to 1D are sectional views illustrating a method for
forming a metal layer according to a first example embodiment of
the present invention;
[0014] FIG. 2 is a schematic view illustrating a reactive ion
etcher in accordance with one embodiment of the present
invention;
[0015] FIG. 3 is scanning electron microscope images illustrating
etching stringers according to a power density in etching
conditions for upper molybdenum;
[0016] FIG. 4 is a plan view illustrating a display substrate
according to an example embodiment of the present invention;
[0017] FIGS. 5A to 8 are cross-sectional views illustrating a
method for manufacturing a display substrate according to a second
example embodiment of the present invention; and
[0018] FIGS. 9 to 12 are cross-sectional views illustrating a
method for manufacturing a display substrate according to a third
example embodiment of the present invention.
DESCRIPTION OF THE EMBODIMENTS
[0019] The invention is described more fully hereinafter with
reference to the accompanying drawings, in which embodiments of the
invention are shown. In the drawings, the size and relative sizes
of layers and regions may be exaggerated for clarity.
[0020] It will be understood that when an element or layer is
referred to as being "on," "connected to" or "coupled to" another
element or layer, it can be directly on, connected or coupled to
the other element or layer or intervening elements or layers may be
present. In contrast, when an element is referred to as being
"directly on," "directly connected to" or "directly coupled to"
another element or layer, there are no intervening elements or
layers present.
[0021] Spatially relative terms, such as "beneath," "below,"
"lower," "above," "upper" and the like, may be used herein for ease
of description to describe one element or feature's relationship to
another element(s) or feature(s) as illustrated in the figures.
[0022] Embodiments of the invention are described herein with
reference to cross-section illustrations that are schematic
illustrations of idealized embodiments (and intermediate
structures) of the invention. As such, variations from the shapes
of the illustrations as a result, for example, of manufacturing
techniques and/or tolerances, are to be expected.
Example Embodiment 1
Method for Forming a Metal Line
[0023] FIGS. 1A to 1D are sectional views illustrating a method for
forming a metal layer according to a first example embodiment of
the present invention. FIG. 2 is a schematic view illustrating a
reactive ion etcher ("RIE") in accordance with one embodiment of
the present invention.
[0024] Referring to FIG. 1A, an insulating layer 110 is formed on a
base substrate 101. A metal line layer 120 is formed on the
insulating layer 110.
[0025] The metal line layer 120 includes a triple layer having a
lower layer 121, a low resistivity metal layer 122, and an upper
layer. The lower layer 121 includes molybdenum or molybdenum alloy.
The low resistivity metal layer 122 includes aluminum or aluminum
alloy. The upper layer 123 includes molybdenum or molybdenum
alloy.
[0026] A photoresist pattern 140 is formed to correspond to a metal
line, via coating and patterning a photoresist layer on the metal
line layer 120. The metal line layer 120 is dry-etched by using the
photoresist pattern 140.
[0027] A dry-etching process, a post-treatment process and an
ashing process which will be explained, are performed by using the
RIE illustrated in FIG. 2.
[0028] Referring to FIG. 2, the RIE 200 includes a vacuum chamber
210, an RF generator 212 and a power supply part 214, so that
etches a substrate 100 by using an etching gas. The vacuum chamber
210 includes a lower electrode 220, a ground cover part 230, an
upper electrode 240, a gas supply part 250, and a vacuum pump part
260.
[0029] The lower electrode 220 is disposed over the ground cover
part 230, and is connected to the RF generator 212 to receive an RF
power. The substrate 100 is disposed on the lower electrode 220.
The upper electrode 240 is disposed over the lower electrode 220,
and is electrically connected to the vacuum chamber 210 directly.
In this case, the upper electrode 240 may be replaced with the
vacuum chamber 210. In this case, the lower electrode 220 is used
as a cathode, and the upper electrode 230 is used as an anode.
[0030] The gas supply part 250 provides a gas that will be used for
the dry-etching, ashing and post-treatment processes into the
vacuum chamber 210. The gas provided by the gas supply part 250 is
discharged by the RF power, so that plasma is formed.
[0031] The vacuum pump part 260 emits the gas inside of the vacuum
chamber 210 into an exterior, so that maintains the vacuum chamber
210 in a vacuum state.
[0032] Then, referring to FIGS. 1A and 2, the dry-etching, ashing
and post-treatment processes on the substrate 100 having the metal
line layer 120 formed on the substrate 100 will be explained.
[0033] Referring to FIGS. 1A and 2, the substrate 100 that has the
photoresist pattern 140 formed on the substrate 100, is disposed on
the lower electrode 220 in the vacuum chamber 210.
[0034] The vacuum chamber 210 is set to a first dry-etching
condition, and then, an oxygen layer (not shown) formed on the
upper layer 121 is removed. The first dry-etching condition is that
a pressure is about 15 mT, a source power is about 2000 W, and the
etching gas of 100BCl.sub.3 is used. The source power and the bias
power that will be explained below are powers applied to the lower
electrode 220.
[0035] Referring to FIGS. 1B and 2, after removing the oxygen layer
formed on the upper layer 123, the vacuum chamber 210 is set to a
second dry-etching condition, and then the upper layer 123 is
etched.
[0036] The second dry-etching condition is that the pressure is
about 15 mT, the source power density which is defined as the
source power divided by an area of the electrode is between about 1
W/cm.sup.2 and about 2 W/cm.sup.2, and the bias power density which
is defined as the bias power divided by the area of the electrode
is between about 0.3 W/cm.sup.2 and about 0.6 W/cm.sup.2. The area
of the electrode is defined as the area of the lower electrode 220.
The etching gas is a mixed gas including a chlorine based gas (for
example, C.sub.12 or HCl) mixed with an additional gas having one
of nitrogen gas (N.sub.2), argon gas (Ar), helium gas (He) and
sulfur hexafluoride gas (SF.sub.6). A ratio of the additional gas
with respect to the chlorine based gas is between about 50% and
about 200%. The upper layer 123 is etched with the second
dry-etching condition, to form the upper pattern 123a.
[0037] Referring to FIGS. 1C and 2, after etching the upper layer
123, the vacuum chamber 210 is set to a third dry-etching
condition, and then the oxygen layer formed on the low-resistivity
metal layer 122 is removed.
[0038] The third dry-etching condition is that the pressure is
about 15 mT, the source power is about 2000 W, and the etching gas
of 20C.sub.12/100BCl.sub.3 that is the chlorine based gas mixed
with BCl.sub.3 is used. The oxygen layer formed on the
low-resistivity metal layer 122 is removed with the third
dry-etching condition.
[0039] After the oxygen layer formed on the low-resistivity metal
layer 122 is removed, the vacuum chamber 210 is set to a fourth
dry-etching condition, and then the low-resistivity metal layer 122
is etched.
[0040] The fourth dry-etching condition is that the pressure is
between about 10 mT and about 30 mT, the source power density is
between about 0.7 and about 1.8, and the bias power density is
between about 0.7 and about 1.8. The mixed gas that is the chlorine
based gas mixed with one of BCl.sub.3 gas, nitrogen gas (N.sub.2)
and argon gas (Ar) is used as the etching gas. Preferably, the
mixed gas that is the chlorine based gas (for example, C.sub.12 or
HCl) mixed with one of nitrogen gas (N.sub.2) and argon gas (Ar) is
used. A ratio of nitrogen gas (N.sub.2) or argon gas (Ar) with
respect to the chlorine based gas is between about 50% and about
150%.
[0041] The low-resistivity metal layer 122 is etched with the
fourth dry-etching condition, to form a low-resistivity pattern
122a.
[0042] Referring to FIGS. 1D and 2, after etching the
low-resistivity metal layer 122, the vacuum chamber 210 is set to a
fifth dry-etching condition, and then, the lower layer 121 is
etched. The fifth dry-etching condition is that the power is
between about 15 mT and about 100 mT, the source power is about
1000 W. The mixed gas that is the chlorine based gas mixed with the
additional gas having one of nitrogen gas (N.sub.2), argon gas
(Ar), helium gas (He) and sulfur hexafluoride gas (SF.sub.6) is
used as the etching gas. The ratio of the additional gas with
respect to the chlorine based gas is about 200%. The lower layer
121 is etched to form a lower pattern 121a.
[0043] According to the dry-etching process, a metal line 120a
having the low resistance is formed on the base substrate 101.
[0044] When forming the metal line, a chlorine ion remains on the
base substrate 101 due to chlorine gas C.sub.12 that the etching
gas includes. When the chlorine ion remaining on the base substrate
101 is exposed to the atmosphere, the chlorine ion is reacted with
moisture in the atmosphere to form hydrochloric acid (HCl). HCl
corrodes the low-resistivity pattern 122a including aluminum (Al),
so that line stringers occur.
[0045] Thus, after forming the metal line, the post-treatment
process is performed to remove the chlorine ion remaining on the
base substrate 101. To perform the post-treatment process, at least
one of H.sub.2 gas and H.sub.20 gas is provided into the vacuum
chamber 210.
[0046] H.sub.2 gas or H.sub.20 gas provided into the vacuum chamber
210 is dissociated by a plasma discharge to generate a hydrogen ion
(H+). The hydrogen ion (H+) is reacted with the chlorine ion
remaining on the base substrate 101, to generate hydrochloric acid
(HCl). HCl generated from the vacuum chamber 210 is generated and
evaporated at the same time due to an equilibrium vapor pressure.
The evaporated HCl is emitted outside of the vacuum chamber 210
through the vacuum pump part 260. Accordingly, the chlorine ion
remaining on the base substrate 101 is removed, so that the
corrosion of the low-resistivity pattern 122a may be prevented.
[0047] Alternatively, the post-treatment process may be performed
by using a fluorine (F) based gas in spite of H.sub.2 gas or
H.sub.20 gas.
[0048] For example, the fluorine based gas provided into the vacuum
chamber 210 is discharged by the RF power, so that the plasma is
formed. Thus, fluorine radical is generated. The fluorine radical
has a better reactivity than the chlorine ion. Thus, the fluorine
radical is reacted with the low-resistivity pattern 122a on an
exposed surface of the low-resistivity pattern 122a, to substitute
the remaining chlorine ion. Accordingly, a corrosion preventing
layer including aluminum fluoride (AlF) is formed on the exposed
surface of the low-resistivity pattern 122a. Thus, the corrosion of
the low-resistivity pattern 122a may be prevented.
[0049] Before the post-treatment process or after the
post-treatment process, oxygen gas is provided into the vacuum
chamber 210, to perform the ashing process that removes the
photoresist.
[0050] Referring to Tables 1, 2, 3 and FIG. 3, effects of etching
the molybdenum layer with the etching conditions of the present
example embodiment will be explained.
[0051] Tables 1, 2, and 3 show etching uniformity of the molybdenum
layer with the etching conditions of the present example
embodiment. The etching uniformity means uniformity in etching
quantity of the molybdenum layer. For example, the etching
uniformity is a value of measuring surface topography after the
etching process, to find out how uniformly the molybdenum layer is
etched in the base substrate. Thus, the surface topography having a
lower value may be better in the uniformity.
[0052] Tables 1, 2 and 3 show results after etching the single
molybdenum layer using a test substrate having the single
molybdenum formed on the test substrate, when a nitrated silicon
layer (g-SiNx), an amorphous silicon layer (a-Si) and an n.sup.+
ion doped layer are sequentially formed.
[0053] Tables 1 and 2 show results after etching an upper
molybdenum layer in the single molybdenum layer including Mo/Al/Mo
layer. Table 3 shows results after etching a lower molybdenum layer
in the single molybdenum layer including Mo/Al/Mo layer.
[0054] Referring to Tables 1, 2 and 3, the oxygen layer was removed
before etching the single molybdenum layer. The etching condition
for removing the oxygen layer was that the pressure was about 15
mT, the source power was about 2000 W, and the etching gas of
100BCl.sub.3 was used.
TABLE-US-00001 TABLE 1 Stacked layer Glass/g-SiNx/a-Si/n.sup.+
a-Si/Mo Mo-t oxygen layer etching condition Pressure(15 mT), Source
power(2000 W), Gas(100BCl.sub.3), Size(20'') Mo-t main etching
condition Comparative Example 1 Example 1 Example 2 Example 3 (#1)
(T#1) (T#2) (T#3) 15 mT, 15 mT, 15 mT, 15 mT, 1500 W, 1500 W, 1500
W, 1500 W, 25Cl.sub.2/50O.sub.2 25Cl.sub.2/50N.sub.2
25Cl.sub.2/50Ar.sub.2 25Cl.sub.2/50He Etching rate 3285 1450 1356
1537 [.ANG./min] Etching 3.7 5.2 3.7 7.9 uniformity [%]
Table 1 shows results after etching the upper molybdenum layer
(Mo-t) with a main etching condition that the pressure was about 15
mT, the source power was about 1500 W, and the ratio of the
additional gas with respect to the chlorine based gas was about
2:1.
[0055] In Comparative Example 1 (#1), the conventional etching gas,
for example the chlorine based gas mixed with oxygen gas (O.sub.2),
was used. In that case, an etching rate (E/R) was about 3285
.ANG./min and the etching uniformity was about 3.7%.
[0056] In Example 1 (T#1), the etching gas including the chlorine
based gas mixed with oxygen gas (O.sub.2), was used. In that case,
the etching rate (E/R) was about 1450 .ANG./min and the etching
uniformity was about 5.2%. In Example 2 (T#2), the etching gas
including the chlorine based gas mixed with argon gas (Ar), was
used. In that case, the etching rate (E/R) was about 1356 .ANG./min
and the etching uniformity was about 3.7%.
[0057] In Example 3 (T#3), the etching gas including the chlorine
based gas mixed with helium gas (He), was used. In that case, the
etching rate (E/R) was about 1537 .ANG./min and the etching
uniformity was about 7.9%.
[0058] When Comparative Example 1 is compared with Examples 1, 2
and 3, the etching rate (E/R) in Examples 1, 2 and 3 is smaller
than that of in Comparative Example 1, but Examples 1, 2 and 3 may
be enough to be applied to the etching process. The etching
uniformity in Example 2 is substantially the same as that in
Comparative Example 1, and the etching uniformity in Examples 1 and
3 is substantially same as that in Comparative Example 1.
TABLE-US-00002 TABLE 2 Stacked layer Glass/g-SiNx/a-Si/n.sup.+
a-Si/Mo Mo-t oxygen layer etching condition Pressure(15 mT), Source
power(2000 W), Gas(100BCl.sub.3), Size(20'') Mo-t main etching
condition Example 4 Example 5 Example 6 (T#4) (T#5) (T#6) 15 mT, 15
mT, 15 mT, 2000 W, 2000 W, 2000 W, 60Cl.sub.2/60N.sub.2
60Cl.sub.2/60Ar.sub.2 60Cl.sub.2/60He Etching rate [.ANG./min] 2338
2406 2431 Etching uniformity [%] 8.9 7.5 8.2
Table 2 shows results after etching the upper molybdenum layer
(Mo-t) with the main etching condition that the pressure was about
15 mT, the source power was about 2000 W, and the ratio of the
additional gas with respect to the chlorine based gas was about
1:1. In Table 2, the ratio of the chlorine based gas in the etching
gas was controlled to be higher than in Table 1.
[0059] In Example 4 (T#4), the etching rate (E/R) was about 2338
.ANG./min and the etching uniformity was about 8.9%. In Example 5
(T#5), the etching rate (E/R) was about 2406 .ANG./min and the
etching uniformity was about 7.5%. In Example 6 (T#6), the etching
rate (E/R) was about 2431 .ANG./min and the etching uniformity was
about 8.2%.
[0060] When Examples 1, 2 and 3 in Table 1 is compared with
Examples 4, 5 and 6 in Table 2, the value of the etching uniformity
in Examples 4, 5 and 6 is increased so that the etching uniformity
is a little worse than in Examples 1, 2 and 3. However, the etching
rate (E/R) is somewhat increased in Examples 4, 5 and 6.
[0061] Accordingly, when Examples 1, 2 and 3 in Table 1 are
compared with Examples 4, 5 and 6 in Table 2, the etching rate
(E/R) is substantially same, and the etching uniformity is
enough.
TABLE-US-00003 TABLE 3 Stacked layer Glass/g-SiNx/a-Si/n.sup.+
a-Si/Mo Mo-b oxygen layer etching condition Pressure(15 mT), Source
power(2000 W), Gas(100BCl.sub.3), Size(20'') Mo-b main etching
condition Comparative Example 2 Example 7 Example 8 Example 9 (#2)
(T#7) (T#8) (T#9) 100 mT, 1000 W, 100 mT, 1000 W, 100 mT, 1000 W,
100 mT, 1000 W, 50Cl.sub.2/200O.sub.2 50Cl.sub.2/200N.sub.2
50Cl.sub.2/200Ar.sub.2 50Cl.sub.2/200He Etching rate 3508 1437 1684
1637 [.ANG./min] Etching uniformity 6.8 6.7 6.9 7.1 [%]
Table 3 shows results after etching the lower molybdenum layer
(Mo-b) with the main etching condition that the pressure was about
100 mT, the source power was about 1000 W, and the ratio of the
additional gas with respect to the chlorine based gas was about
4:1.
[0062] In the main etching condition of the lower molybdenum layer
(Mo-b), a selective ratio should be higher than in the main etching
condition of the upper molybdenum layer (Mo-t) illustrated in
Tables 1 and 2, to prevent the n.sup.+ ion doped layer (n.sup.+
a-Si) that is formed under the lower molybdenum layer (Mo-b) from
being etched. Accordingly, the ratios of the pressure and the
additional gas are increased.
[0063] In Comparative Example 2 (#2), the conventional etching gas,
for example the chlorine based gas mixed with oxygen gas (O.sub.2),
was used. In that case, an etching rate (E/R) was about 3509
.ANG./min and the etching uniformity was about 6.8%.
[0064] In Example 7 (T#7), the etching gas including the chlorine
based gas mixed with nitrogen gas (N.sub.2), was used. In that
case, the etching rate (E/R) was about 1437 .ANG./min and the
etching uniformity was about 6.7%.
[0065] In Example 8 (T#8), the etching gas including the chlorine
based gas mixed with argon gas (Ar), was used. In that case, the
etching rate (E/R) was about 1684 .ANG./min and the etching
uniformity was about 6.9%.
[0066] In Example 9 (T#9), the etching gas including the chlorine
based gas mixed with helium gas (He), was used. In that case, the
etching rate (E/R) was about 1637 .ANG./min and the etching
uniformity was about 7.1%.
[0067] When Comparative Example 2 is compared with Examples 7, 8
and 9, the etching rate (E/R) in Examples 7, 8 and 9 is smaller
than that in Comparative Example 2, but Examples 7, 8 and 9 may be
enough to be applied to the etching process. The etching uniformity
in Examples 7, 8 and 9 is substantially same as in Comparative
Example 2.
[0068] Therefore, as illustrated in Tables 1, 2 and 3, the etching
uniformity in etching the upper and lower molybdenum layers (Mo-t,
Mo-b) using the mixed gas including the chlorine based gas mixed
with the additional gas having one of nitrogen gas (N.sub.2), argon
gas (Ar) and helium gas (He), is substantially same as that in
etching the upper and lower molybdenum layers using conventional
oxygen gas (O2).
[0069] FIG. 3 is scanning electron microscope ("SEM") images
illustrating etching stringers according to a power density in
etching conditions for upper molybdenum.
[0070] The SEM pictures illustrated in FIG. 3, show a channel
portion and a line portion, after etching the upper molybdenum
layer having the Mo/Al/Mo layer with the corresponding source power
density and bias power density conditions, and then sequentially
etching the aluminum layer and the lower molybdenum layer.
[0071] Comparative Example 3 (#3) shows the channel and line
portions, after etching the upper molybdenum layer with the
condition that the source power density was about 0.365 W/cm.sup.2
and the bias power density was about 0.122 W/cm.sup.2. Comparative
Example 4 (#4) shows the channel and line portions, after etching
the upper molybdenum layer with the condition the source power
density was about 0.73 W/cm.sup.2 and the bias power density was
about 0.244 W/cm.sup.2.
[0072] Referring to the SEM pictures of Comparative Example 3 and
Comparative Example 4, a surface of the etched metal pattern
includes metal remnants, and the metal remnants having a stringer
remain at an edge portion of the etched metal pattern.
[0073] Example 10 (T#10) shows the line portion, after etching the
upper molybdenum layer with the condition that the source power
density was about 1.095 W/cm.sup.2 and the bias power density was
about 0.366 W/cm.sup.2. Example 11 (T#11) shows the channel and
line portions, after etching the upper molybdenum layer with the
condition that the source power density was about 1.825 W/cm.sup.2
and the bias power density was about 0.61 W/cm.sup.2.
[0074] Referring to the SEM pictures of Example 10 and Example 11,
the surface and the edge portion of the etched metal pattern
include little metal remnants. The stringer due to the metal
remnants does not occur in the power densities used in Example 10
and Example 11.
Example Embodiment 2
Method for Manufacturing a Display Substrate
[0075] FIG. 4 is a plan view illustrating a display substrate
according to an example embodiment of the present invention. FIGS.
5A to 8 are cross-sectional views illustrating a method for
manufacturing a display substrate according to a second example
embodiment of the present invention.
[0076] FIGS. 5A and 5B are cross-sectional views illustrating the
method for manufacturing the display substrate using a first
mask.
[0077] Referring to FIGS. 4, 5A and 5B, a gate metal layer 310 is
deposited on a base substrate 101 via a sputtering process. The
gate metal layer 310 includes a double layer having a
low-resistivity metal layer 311 and an upper layer 312. For
example, the low-resistivity metal layer 311 includes aluminum or
aluminum alloy, and the upper layer 312 includes molybdenum or
molybdenum alloy.
[0078] A first photoresist layer is formed on the gate metal layer
310, and then the first photoresist layer is patterned using the
first mask, to form a first photoresist pattern PR1. The gate metal
layer 310 is etched using the first photoresist pattern PR1, to
form a gate pattern including a gate line GLn, a gate electrode GE
and a storage common line STL.
[0079] The gate metal layer 310 may be wet-etched or dry-etched.
Preferably, as explained above in FIGS. 1A to 1C, in etching the
gate metal layer 310, an oxygen layer of the upper layer 312, the
upper layer 312, the oxygen layer of the low-resistivity metal
layer 311 and the low-resistivity metal layer 311 are sequentially
etched with the first to fourth dry-etching conditions.
[0080] FIGS. 6A to 6D are cross-sectional views illustrating the
method for manufacturing the display substrate using a second
mask.
[0081] Referring to FIGS. 4 and 6A, a gate insulating layer 320 and
a semiconductor layer 330 including a silicon nitride (SiNx) layer
are formed on the base substrate 301 on which the gate pattern is
formed, via a plasma enhanced chemical vapor deposition ("PECVD")
process. The semiconductor layer 330 includes an active layer 331
having amorphous silicon (a-Si:H), and an ohmic contact layer 332
doped with n.sup.+ ion at a high concentration.
[0082] Then, a source metal layer 340 is deposited on the ohmic
contact layer 332. The source metal layer 340 has a triple layer
including a lower layer 341, a low-resistivity metal layer 342 and
an upper layer 343 sequentially formed. The lower layer 341
includes molybdenum or molybdenum alloy, the low-resistivity metal
layer includes aluminum or aluminum alloy, and the upper layer
includes molybdenum or molybdenum alloy.
[0083] A second photoresist layer is formed on the base substrate
301 on which the source metal layer 340 is formed, and then, a
second photoresist pattern (PR2) is formed by using the second mask
having a slit.
[0084] The second photoresist pattern PR2 includes a first picture
pattern PR21 and a second picture pattern PR22. The first picture
pattern PR21 corresponds to an area in which a source electrode SE,
a drain electrode DE, and a source line DLm of a switching element
TFT are formed. The second picture pattern PR22 corresponds to an
area in which a channel portion CH of the switching element TFT is
formed, and the second picture pattern PR22 has a thinner thickness
than that of the first picture pattern PR21.
[0085] Referring to FIGS. 4 and 6B, the source metal layer 340 is
patterned by using the second photoresist pattern PR2, so that the
source pattern having an electrode pattern 340a and the source line
DLm is formed. The electrode pattern 340a corresponds to the source
and drain electrodes of the switching element TFT.
[0086] The source metal layer 340 is wet-etched. In addition, as
explained above in FIGS. 1A to 1D, the source metal layer 340 that
is wet-etched may include a better accurate pattern than the source
metal layer 340 that is etched with the first to fifth dry-etching
conditions.
[0087] Referring to FIGS. 4, 6C and 6D, after forming the source
pattern, the semiconductor layer 330 is etched using the second
photoresist pattern and the source pattern as a mask. Accordingly,
semiconductor patterns 330a and 330b that are patterned along the
source pattern, are formed under the source pattern.
[0088] The second photoresist pattern PR2 is removed to have a
predetermined thickness using an oxygen (O2) plasma discharge via
the ashing process (or etch back process). The electrode pattern
340a corresponding to the channel portion CH of the switching
element TFT is partially exposed via the ashing process. A
remaining pattern PR23 of the second photoresist pattern PR2 is
formed on the area in which the source electrode SE, the drain
electrode DE, and the source line DLm are formed, via the ashing
process.
[0089] The exposed electrode pattern 340a is dry-etched by using
the remaining pattern PR23 as the mask.
[0090] The upper layer 343 of the electrode pattern 340a is etched
with the first and second dry-etching conditions, as explained
above in FIGS. 1A and 1B. For example, the oxygen layer formed on
the upper layer 343 is etched with the first condition that the
pressure is about 15 mT, the source power is about 2000 W, and the
etching gas of 100BCl.sub.3 is used. After removing the oxygen
layer formed on the upper layer 343, the upper layer 343 is etched
with the second dry-etching condition.
[0091] The second dry-etching condition is that the pressure is
about 15 mT, the source power density is between about 1 W/cm.sup.2
and about 2 W/cm.sup.2, and the bias power density is between about
0.3 W/cm.sup.2 and about 0.6 W/cm.sup.2. The mixed gas including
the chlorine based gas is mixed with the additional gas having one
of argon gas (Ar), nitrogen gas (N.sub.2), helium gas (He) and
sulfur hexafluoride gas (SF.sub.6). The ratio of the additional gas
with respect to the chlorine based gas is between about 50% and
about 200%.
[0092] After etching the upper layer 343, the low-resistivity metal
layer 342 of the electrode pattern 340a, as illustrated in FIG. 1,
is etched with the third and fourth dry-etching conditions. The
oxygen layer formed on the low-resistivity metal layer 342 is
etched with the third dry-etching condition that the pressure is
about 15 mT, the source power is about 2000 W and the etching gas
of 20Cl.sub.2/100BCl.sub.3 is used.
[0093] After removing the oxygen layer formed on the
low-resistivity metal layer 342, the low-resistivity metal layer
342 is etched with the fourth dry-etching condition. The fourth
dry-etching condition is that the pressure is between about 10 mT
and 30 mT, the source power density is between about 0.7 W/cm.sup.2
and about 1.8 W/cm.sup.2, and the bias power density is between
about 0.7 W/cm.sup.2 and about 1.8 W/cm.sup.2. The mixed gas
including the chlorine based gas mixed with argon gas (Ar) or
nitrogen gas (N.sub.2) is used as the etching gas. The ratio of the
argon gas (Ar) or nitrogen gas (N.sub.2) with respect to the
chlorine based bas is between about 50% and about 150%.
[0094] After etching the low-resistivity metal layer 342, as
explained above in FIG. 1D, the lower layer 341 of the electrode
pattern 340a is etched with the fifth dry-etching condition.
[0095] The electrode pattern 340a is patterned to be the source
electrode SE and the drain electrode DE, via the dry-etching
process mentioned above. The ohmic contact layer 332 exposed
between the source and drain electrodes SE and DE is dry-etched by
using the source and drain electrodes SE and DE as the mask. Thus,
the channel portion CH through which the active layer 331 is
exposed, is formed between the source and drain electrodes SE and
DE, so that the switching element TFT is formed.
[0096] After the fifth dry-etching process, the chlorine ion
provided from the chlorine based etching gas is reacted with the
low-resistivity metal layer 342 including aluminum or aluminum
alloy, to remain on an exposed surface of the low-resistivity metal
layer 342. The post-treatment process is performed to remove the
remaining chlorine ion. The surface of the low-resistivity metal
layer 342 is prevented from being corroded, via the post-treatment
process. The post-treatment process is performed with the same
condition as the first example embodiment.
[0097] FIG. 7 is a cross-sectional view illustrating the method for
manufacturing the display substrate using a third mask. FIG. 8 is a
cross-sectional view illustrating the method for manufacturing the
display substrate using a fourth mask.
[0098] Referring to FIGS. 4, 7 and 8, a protective insulating layer
350 is formed on the base substrate 301 on which the switching
element TFT is formed. The protective insulating layer 350 includes
the silicon nitride layer. A contact hole 353 that partially
exposes the drain electrode DE, is formed via a photolithography
process using the third mask.
[0099] The protective insulating layer 350 including the silicon
nitride layer is explained in the present example embodiment, but
the protective insulating layer 350 may include an organic layer
such as an acrylic material. In addition, the protective insulating
layer 350 may include the double layer having the silicon nitride
layer and the organic layer sequentially formed.
[0100] A transparent conductive material (not shown) is deposited
on the protective insulating layer 350 in which the contact hole
353 is formed. Examples of materials that can be used for the
transparent conductive material may include indium tin oxide or
indium zinc oxide. Accordingly, the transparent conductive material
is connected to the drain electrode DE through the contact hole
353. The transparent conductive material is patterned by using the
fourth mask, to form a pixel electrode PE. The pixel electrode PE
is electrically connected to the switching element TFT through a
contact portion CNT.
Example Embodiment 3
Method for Manufacturing a Display Substrate
[0101] FIGS. 9 to 12 are cross-sectional views illustrating a
method for manufacturing a display substrate according to a third
example embodiment of the present invention. The same reference
numerals will be used to refer to the same or like parts as those
described in the second example embodiment and any further
repetitive explanation concerning the above elements will be
omitted.
[0102] FIG. 9 is a cross-sectional view illustrating the method for
manufacturing the display substrate using a first mask and a second
mask.
[0103] Referring to FIGS. 4 and 9, a gate pattern including a gate
line GLn, a gate electrode GE and a storage common line STL, is
formed on a base substrate 301 by using the first mask. The gate
pattern includes a double layer having a low-resistivity metal
layer 311 and an upper layer 312. The low-resistivity metal layer
311 includes aluminum or aluminum alloy, and the upper layer 312
includes molybdenum or molybdenum alloy. The gate metal layer 310
may be wet-etched or dry-etched. Preferably, as explained above in
FIGS. 1A to 1C, the gate metal layer is sequentially etched with
the first to fourth dry-etching conditions.
[0104] A gate insulating layer 320, an active layer 331 and an
ohmic contact layer 332 are sequentially formed on the base
substrate 301 on which the gate pattern is formed. A semiconductor
layer 330 of the switching element TFT is formed by using a second
photoresist pattern PR2 which is patterned by the second mask.
[0105] FIGS. 10A and 10B are cross-sectional views illustrating the
method for manufacturing the display substrate using a third
mask.
[0106] Referring to FIGS. 4, 10A and 10B, a source metal layer 340
is formed on the base substrate 301 on which the semiconductor
layer 330 of the switching element TFT is formed. The source metal
layer 340 including a triple layer having a lower layer 341, a
low-resistivity metal layer 342 and an upper layer 342 is
sequentially formed. The lower layer 341 includes molybdenum or
molybdenum alloy, the low-resistivity metal layer 342 includes
aluminum or aluminum alloy, and the upper layer 342 includes
molybdenum or molybdenum alloy.
[0107] The source metal layer 340 is etched by using a third
photoresist pattern PR3 that is patterned by the third mask, to
form a source pattern including a source electrode SE, a drain
electrode DE and a source line DLm. The source metal layer 340, as
explained above in FIGS. 1A to 1D, is etched with the first to
fifth dry-etching conditions, to form the source pattern.
[0108] A channel portion CH is formed by using the source and drain
electrodes SE and DE as a mask. The base substrate 301 on which the
channel portion CH is formed is treated via the post-treatment
process, to prevent the low-resistivity metal layer 342 of the
source pattern from being corroded.
[0109] FIGS. 11 and 12 are cross-sectional views illustrating the
method for manufacturing the display substrate using a fourth mask
and a fifth mask.
[0110] Referring to FIGS. 4, 11 and 12, a protective insulating
layer 350 is formed on the base substrate 301 on which the channel
portion CH is formed, and a contact hole 353 is formed using the
fourth mask. A transparent conductive material is deposited to make
contact with the drain electrode DE through the contact hole 353.
Then, the transparent conductive material is patterned using the
fifth mask, to form a pixel electrode PE.
[0111] According to the present invention, the mixed gas including
the chlorine based gas (for example, C.sub.12 or HCl) mixed with
the additional gas having one of nitrogen gas (N.sub.2), argon gas
(Ar), helium gas (He) and sulfur hexafluoride gas (SF.sub.6), is
used for dry-etching of the upper layer including molybdenum formed
on the aluminum layer, so that the stringer remaining on the metal
layer due to the etching gas including oxygen gas may be
removed.
[0112] In addition, with the etching condition is that the mixed
gas including nitrogen gas (N.sub.2), argon gas (Ar) or helium gas
(He) is used, the source power density is between about 1
W/cm.sup.2 and about 2 W/cm.sup.2, and the bias power density is
between about 0.3 W/cm.sup.2 and about 0.6 W/cm.sup.2, the stringer
remaining on the metal layer may be remarkably enhanced.
Accordingly, the line stringer of the low-resistivity line
including aluminum is removed, so that the metal line may be more
accurate.
Having described the example embodiments of the present invention
and its advantage, it is noted that various changes, substitutions,
and alterations can be made herein without departing from the
spirit and scope of the invention as defined by appended
claims.
* * * * *