U.S. patent application number 12/492152 was filed with the patent office on 2010-12-30 for method of etching a multi-layer.
Invention is credited to Shi Jie Bai, Zhen Yu Zhuo.
Application Number | 20100326954 12/492152 |
Document ID | / |
Family ID | 43379586 |
Filed Date | 2010-12-30 |
![](/patent/app/20100326954/US20100326954A1-20101230-D00000.TIF)
![](/patent/app/20100326954/US20100326954A1-20101230-D00001.TIF)
![](/patent/app/20100326954/US20100326954A1-20101230-D00002.TIF)
![](/patent/app/20100326954/US20100326954A1-20101230-D00003.TIF)
![](/patent/app/20100326954/US20100326954A1-20101230-D00004.TIF)
United States Patent
Application |
20100326954 |
Kind Code |
A1 |
Zhuo; Zhen Yu ; et
al. |
December 30, 2010 |
METHOD OF ETCHING A MULTI-LAYER
Abstract
A method of etching a multi-layer is provided. The multi-layer
includes an aluminum layer disposed on a semiconductor substrate
and an anti-reflection coating layer disposed on the aluminum
layer. The method includes: performing a first etching process to
etch the anti-reflection coating layer by providing a first etching
gas, wherein the first etching gas includes a chlorine-containing
substance; then performing a second etching process to etch the
aluminum layer by providing a second etching gas, wherein the
second etching gas does not include a chlorine-containing
compound.
Inventors: |
Zhuo; Zhen Yu; (Singpore,
SG) ; Bai; Shi Jie; (Singpore, SG) |
Correspondence
Address: |
NORTH AMERICA INTELLECTUAL PROPERTY CORPORATION
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
43379586 |
Appl. No.: |
12/492152 |
Filed: |
June 26, 2009 |
Current U.S.
Class: |
216/24 ;
216/77 |
Current CPC
Class: |
C23F 4/00 20130101; H01L
21/32136 20130101 |
Class at
Publication: |
216/24 ;
216/77 |
International
Class: |
C23F 1/02 20060101
C23F001/02 |
Claims
1. A method of etching a multi-layer, the multi-layer comprising an
aluminum layer disposed on a semiconductor substrate and an
anti-reflection coating (ARC) layer disposed on the aluminum layer,
the method comprising: performing a first etching process to etch
the ARC layer by providing a first etching gas, wherein the first
etching gas comprises a chlorine-containing substance; and
performing a second etching process to etch the aluminum layer by
providing a second etching gas, wherein the second etching gas does
not comprise a chlorine-containing compound.
2. The method as in claim 1, wherein the chlorine-containing
compound comprises BCl.sub.3.
3. The method as in claim 1, wherein the second etching gas
comprises chlorine gas.
4. The method as in claim 1, wherein the first etching gas
comprises chlorine gas and BCl.sub.3.
5. The method as in claim 1, wherein the first etching gas
comprises chlorine gas.
6. The method as in claim 1, wherein the first etching process
further comprises providing a first passivation gas.
7. The method as in claim 6, wherein the first passivation gas
comprises hydrocarbon.
8. The method as in claim 6, wherein the first passivation gas
comprises ethylene (C.sub.2H.sub.4).
9. The method as in claim 1, wherein the second etching process
further comprises providing a second passivation gas.
10. The method as in claim 9, wherein the second passivation gas
comprises hydrocarbon.
11. The method as in claim 9, wherein the second passivation gas
comprises ethylene.
12. The method as in claim 6, wherein the first etching process is
performed under a condition as follows: a pressure between 12 and
18 mTorr, a RF power between 1200 and 1600 W, a bias power between
250 W and 350 W, a period between 120 and 180 seconds, a flow rate
of the first etching gas between 150 and 210 sccm and a flow rate
of the first passivation gas between 120 and 180 sccm.
13. The method as in claim 9, wherein the second etching process is
performed under a condition as follows: a pressure between 8 and 12
mTorr, a RF power between 1300 and 1700 W, a bias power between 250
W and 350 W, a flow rate of the second etching gas between 120 and
180 sccm and a flow rate of the second passivation gas between 120
and 180 sccm.
14. A method of anisotropically etching an aluminum layer,
comprising: providing an etching gas to etch the aluminum layer,
wherein the etching gas comprises a chlorine-containing substance,
but does not comprise a chlorine-containing compound.
15. The method as in claim 14, wherein the chlorine-containing
compound comprises BCl.sub.3.
16. The method as in claim 14, wherein the etching gas comprises
chlorine gas.
17. The method as in claim 14, further comprising providing a
passivation gas.
18. The method as in claim 17, wherein the passivation gas
comprises hydrocarbon.
19. The method as in claim 17, wherein the passivation gas
comprises ethylene.
20. The method as in claim 17, wherein the etching process is
performed under a condition as follows: a pressure between 8 and 12
mTorr, a RF power between 1300 and 1700 W, a bias power between 250
W and 350 W, a flow rate of the etching gas between 120 and 180
sccm and a flow rate of the passivation gas between 120 and 180
sccm.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method of etching a
multi-layer, especially to a method that can prevent excess polymer
residue on the sidewall and the corrosion of the aluminum
layer.
[0003] 2. Description of the Prior Art
[0004] In modern society, the micro-processor system comprised of
integrated circuits (IC) is a ubiquitous device, being utilized in
such diverse fields as automatic control electronics, mobile
communication devices and personal computers.
[0005] To connect various active or passive components on the
semiconductor substrate, metal aluminum or its alloy is usually
used as a conducting wire. By some patterning processes, a complex
interconnection system is gradually formed. A conventional method
of forming a patterned aluminum layer is to deposit a photoresist
layer on the aluminum layer, and then performing a
photo-etching-process (PEP) with a patterned photo mask, then
transferring the pattern of the photoresist layer onto the aluminum
layer.
[0006] Please refer to FIG. 1, illustrating a cross sectional
schematic diagram of a conventional method of forming a patterned
aluminum layer. As shown in FIG. 1, a semiconductor substrate (not
shown) is provided and a dielectric layer 10, a barrier layer 12,
an aluminum layer 14, an anti-reflection coating (ARC) layer 16 and
a photoresist layer 22 are disposed in series thereon. The barrier
layer 12 is an optional structure and may include Ti/TiN or TaN.
The barrier layer 12 is usually used in a conventional via plug
forming process to cover the external layer of the via plug or to
increase its adhesion. The ARC layer 16 is used to reduce the
reflection phenomenon during the exposure process.
[0007] Due to the different materials of each layer in the
multi-layer, it is necessary to use different etching gas recipes
to accurately remove the ARC layer 16 and the aluminum layer 14.
The etching gas recipes usually include chlorine gas, BCl.sub.3
N.sub.2, CHF.sub.3 or hydrocarbon. The chlorine gas and BCl.sub.3
are used as the etching gas to anisotropically etch the ARC layer
16 and the aluminum layer 14 when they are transferred to radical
by the plasma in the etching chamber. In order to maintain the good
directionality, a passivation gas is used to produce polymer on the
sidewall to obtain a good sidewall protection.
[0008] It is known that BCl.sub.3 can not only function as an
etching gas but also has passivation effect. It has therefore been
widely used in various anisotropic etching processes. However,
using BCl.sub.3 may also bring some shortcomings such as excess
loose polymer residue formed on the sidewall and thus the corrosion
of the aluminum layer or other shortcomings. As shown in FIG. 1, it
is known that BCl.sub.3 has passivation effect, but if BCl.sub.3
and other passivation substances are used at the same time, excess
polymer residue 24 is formed on the sidewall which is not compact.
And because of the excess loose polymer residue 24 on the sidewall,
lots of Cl.sub.plasma generated by the plasma is easily attached
onto the polymer residue 24 and reacted with the aluminum layer 14
in the sidewall. Please refer to FIG. 2, illustrating a schematic
diagram of a conventional aluminum corrosion reaction formed by the
Cl.sub.plasma. Please refer to FIG. 2. When the aluminum (Al(s)) in
the aluminum layer 14 reacts with the Cl radical (Cl.sub.plasma), a
gaseous and aqueous intermediate product AlCl.sub.x is produced. If
the aqueous AlCl.sub.x comes in contact with water (H.sub.2O), it
will produce aluminum hydroxide (Al(OH).sub.x) and gaseous and
aqueous hydrochloric acid (HCl.sub.(g)+(aq)). Formed aqueous
hydrochloric acid then soon reacts with the aluminum layer 14 and
regenerates with AlCl.sub.x. So the cycle re-entries the foregoing
and continues to cycle indefinitely, making the aluminum layer 14
being etched seriously and leading to the phenomenon of aluminum
layer corrosion. Although the action can be avoided by blocking of
H.sub.2O, but it will further increase the burden of the
controlling factors required in the etching process, making it
become a complex process.
[0009] As a result, a simple etching process to etch the aluminum
layer and the ARC layer that can prevent excess polymer residue
production and corrosion of aluminum layer is still needed.
SUMMARY OF THE INVENTION
[0010] The present invention provides a method of etching a
multi-layer, especially a method that can reduce the phenomenon of
excess polymer residue and can produce more compact polymer residue
so as to prevent the corrosion of aluminum layer in the
multi-layer.
[0011] According to the present invention, a method of etching a
multi-layer is provided. The multi-layer comprises an aluminum
layer disposed on a semiconductor substrate and an anti-reflection
coating layer disposed on the aluminum layer. The method comprises:
performing a first etching process to etch the anti-reflection
coating layer by providing a first etching gas, wherein the first
etching gas comprises a chlorine-containing substance; then
performing a second etching process to etch the aluminum layer by
providing a second etching gas, wherein the second etching gas does
not comprise a chlorine-containing compound.
[0012] According to the present invention, a method of
anisotropically etching an aluminum layer is provided. The method
comprises: providing an etching gas to etch the aluminum layer,
wherein the etching gas comprises a chlorine-containing substance,
but does not comprise a chlorine-containing compound.
[0013] The method of etching a multi-layer in the present invention
excludes chlorine-containing compound as an etching gas, not only
providing a more simple process but also reducing the phenomenon of
excess polymer residue and corrosion of aluminum layer, and leading
to a better etching result.
[0014] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 illustrates a cross sectional schematic diagram of a
conventional method of forming a patterned aluminum layer.
[0016] FIG. 2 illustrates a schematic diagram of a conventional
aluminum corrosion reaction formed by the Cl.sub.plasma.
[0017] FIG. 3 illustrates a flow chart of etching a multi-layer in
the present invention.
[0018] FIG. 4 to FIG. 7 illustrate the structure schematic diagrams
of each step of etching a multi-layer in the present invention.
DETAILED DESCRIPTION
[0019] Please refer to FIG. 3, illustrating a flow chart of etching
a multi-layer in the present invention. As shown in FIG. 3, the
method of etching a multi-layer in the present invention
comprises:
[0020] Step 100: providing a multi-layer disposed on a
semiconductor substrate, wherein the multi-layer comprises at least
an aluminum layer and an anti-reflection coating (ARC) layer
disposed on the aluminum layer.
[0021] Step 102: utilizing a patterned mask to perform a first
etching process to etch the ARC layer by providing a first etching
gas and a first passivation gas, wherein the first etching gas
comprises a chlorine-containing substance.
[0022] Step 104: after step 102, performing a second etching
process to etch the aluminum layer by providing a second etching
gas and a second passivation gas, wherein the second etching gas
does not comprise a chlorine-containing compound.
[0023] Step 106: after etching the aluminum layer, performing an
over etching process to etch a barrier layer disposed under the
aluminum layer.
[0024] For more detailed descriptions of each step, please refer to
FIG. 4 to FIG. 7, illustrating the structure schematic diagrams of
each step of etching a multi-layer in the present invention. As
shown in FIG. 4 and step 100, a multi-layer on a semiconductor
substrate 108 is provided. The multi-layer in series includes a
dielectric layer 110, a barrier layer 112, an aluminum layer 114,
an ARC layer 116 and a mask layer 122. The dielectric layer 110
includes SiO.sub.2, SiN, SiC, tetraethoxysilane (TEOS), undoped
silicon glass (USG), phosphorus silicon glass (PSG), boron
phosphorus silicon glass (BPSG), other low-k dielectric material or
the combination of above groups. The barrier layer 112 includes
Ti/TiN, TaN, other suitable material or the combination of above
groups. The aluminum layer 114 may include conventional metal
aluminum or aluminum alloy such as copper-aluminum alloy. The ARC
layer 116 includes Ti/TiN or other suitable material. The ARC layer
116 may include a mono-layer structure or a double-layer structure,
for example, a bottom ARC layer and a top ARC layer. The bottom ARC
layer includes TiN. The top ARC layer may include the same material
as the bottom ARC layer or include different materials, such as an
organic anti-reflection material, or inorganic anti-refection
material like silicon oxynitride (SiON). The mask layer 122
includes a patterned structure, such as a photoresist, wherein the
pattern of the mask layer 122 will be transferred to the ARC layer
116 and the aluminum layer 114 in the subsequent etching steps.
[0025] Please refer to FIG. 5 and step 102. A first etching process
is provided to etch the ARC layer 116 but less to etch the aluminum
layer 114. After step 102 is performed, most ARC layer 116 is
etched away and even a small part of the aluminum layer 114 is
consumed. In some circumstance, a small part of the ARC layer 116
may still be retained on the substrate 108. A first etching gas 126
and a first passivation gas are provided therefore. The first
etching gas 126 includes various kinds of chlorine-containing
substance but does not include a chlorine-containing compound, for
instance, using only chlorine gas but not using BCl.sub.3. In
another embodiment of the present invention, the first etching gas
126 used to etch the ARC layer 116 but less to etch the aluminum
layer 114 may also include all chlorine-containing substances,
which means using the chlorine gas and various kinds of
chlorine-containing compounds at the same time, for example, using
chlorine gas and BCl.sub.3 at the same time. The first passivation
gas includes hydrocarbon or other suitable material, in the
preferred embodiment of the present invention, the first
passivation gas is ethylene (C.sub.2H.sub.4).
[0026] The first etching process is carried out in a plasma etching
chamber. Table 1 provides a preferred etching recipe and operation
condition when the first etching gas 126 is chlorine gas. As shown
in Table 1, the first etching process is performed under a
condition as follows: a pressure between 12 and 18 mTorr, a RF
power between 1200 and 1600 W, a bias power between 250 W and 350
W, a period between 120 and 180 seconds, a flow rate of chlorine
gas between 150 and 210 sccm (standard cubic centimeter per minute)
and a flow rate of ethylene between 120 and 180 sccm. The reaction
time of the first etching process may be adjusted depending on the
material or thickness of the ARC layer 116. It can be longer or
short and is not limited to Table 1.
TABLE-US-00001 TABLE 1 Step Step 102 Step 104 Step 106 First
etching Second etching Over etching process process process Time
(sec) 150 End point 120 detection (max = 400) RF power (W) 1400
1500 1200 Bias power (W) 300 300 1500 Pressure (mTorr) 15 10 8
BCl.sub.3 (sccm) 0 0 100 Cl.sub.2 (sccm) 180 150 100 C.sub.2H.sub.4
(sccm) 150 150 150
[0027] Please refer to FIG. 6 and step 104. After etching the ARC
layer 116, a second etching process to etch the aluminum layer 114
is provided. A second etching gas 128 and a second passivation gas
are provided. In order to avoid forming excess polymer residue that
results in serious etching and corrosion of the aluminum layer 114
by using BCl.sub.3 in conventional arts, the second etching gas 128
in the present invention includes a chlorine-containing substance
but does not include a chlorine-containing compound, for example,
using only chlorine-containing substance such as chlorine gas but
avoiding conventional chlorine-containing compound such as
BCl.sub.3. The second passivation gas includes hydrocarbon or other
suitable material, in the preferred embodiment of the present
invention, the second passivation gas is C.sub.2H.sub.4. The second
etching process can also be carried out in-situ in the plasma
etching chamber. Referring to Table 1, the second etching process
is performed under a condition as follows: a pressure between 8 and
12 mTorr, a RF power between 1300 and 1700 W, a bias power between
250 W and 350 W, a flow rate of the first etching gas between 120
and 180 sccm and a flow rate of the first passivation gas between
120 and 180 sccm. It is noted that the reaction time of the second
etching process is determined by the end point detection. When the
thickness of the aluminum layer 114 or other metal layer is
changed, the reaction time of the second etching process is
adjusted as well. The time listed in Table 1 provides one
embodiment and the etching method of the present invention should
not be limited thereto.
[0028] When finishing step 102 and step 104, the pattern of the
mask layer 122 has been transferred to the aluminum layer 114,
forming a patterned aluminum layer 114. Referring to FIG. 7, as
shown in step 106, an over etching process is in-situ provided. A
third etching gas 130 is provided to etch the barrier layer 112 and
some remained aluminum layer 114 on the substrate 108. A part of
the dielectric layer 110 may be consumed in the third etching
process to make sure the aluminum layer 114 and the barrier layer
112 being etched away completely. The etching recipe and operation
condition are shown in Table 1, which is not described in detail.
After step 106, the polymer residue is flushed by argon gas and the
mask layer 122 is removed, the patterned aluminum layer 114 is thus
completed.
[0029] As described above, BCl.sub.3 is usually used as an etching
and a passivation gas in conventional arts, which may results in
excess polymer residue formed on the sidewall of the patterned
aluminum layer and thus brings to the serious etching and even
corrosion of the aluminum layer. The present invention therefore
provides an etching method that avoids using chlorine-containing
compound such as BCl.sub.3 as an etching gas, and in combination
with a passivation gas such as hydrocarbon. In conventional arts,
BCl.sub.3 produces sidewall polymer by bombarding the mask layer,
but the formed sidewall polymer is usually not compact. In
contrast, hydrocarbon has longer polymer chains and thus more
condensed structure ([C--H]x), it can completely replace the
passivation function of BCl.sub.3. The sidewall protection is not
reduced with the removal of BCl.sub.3. On the contrary, removing
BCl.sub.3 can avoid corrosion of the aluminum layer caused by too
much Cl.sub.plasma trapped in the polymer residue. As a result, the
method of etching a multi-layer in the present invention not only
provides a simpler process by removing chlorine-containing compound
as an etching gas, but also can reduce the phenomenon of excess
polymer residue and corrosion of aluminum layer, leading to a
better etching result.
[0030] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention.
* * * * *