U.S. patent application number 09/729202 was filed with the patent office on 2001-08-02 for method for fabricating an electronic device.
Invention is credited to Miyoshi, Yuichi, Nagai, Toshihiko.
Application Number | 20010010974 09/729202 |
Document ID | / |
Family ID | 18387649 |
Filed Date | 2001-08-02 |
United States Patent
Application |
20010010974 |
Kind Code |
A1 |
Nagai, Toshihiko ; et
al. |
August 2, 2001 |
Method for fabricating an electronic device
Abstract
After forming a processed film onto the underlying film formed
on the substrate, the processed film is dry etched using a mask
pattern so as to form an etched pattern. After the reaction product
deposited on a wall of the etched pattern is removed by using the
first cleaning solution having relatively low power to etch the
processed film and the second cleaning solution having relatively
high power to etch the processed film in that order, the etched
pattern or its vicinity is rinsed with water.
Inventors: |
Nagai, Toshihiko; (Osaka,
JP) ; Miyoshi, Yuichi; (Osaka, JP) |
Correspondence
Address: |
NIXON PEABODY, LLP
8180 GREENSBORO DRIVE
SUITE 800
MCLEAN
VA
22102
US
|
Family ID: |
18387649 |
Appl. No.: |
09/729202 |
Filed: |
December 5, 2000 |
Current U.S.
Class: |
438/745 ;
257/E21.252; 257/E21.577; 438/689 |
Current CPC
Class: |
H01L 21/76805 20130101;
H01L 21/76814 20130101; H01L 21/31116 20130101 |
Class at
Publication: |
438/745 ;
438/689 |
International
Class: |
H01L 021/302 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 7, 1999 |
JP |
11-347059 |
Claims
What is claimed is:
1. A method for fabricating an electronic device comprising: a
first process of forming an insulator film onto a conductive
pattern formed on a substrate; a second process of forming an
opening portion in said insulator film by dry etching said
insulator film using a resist pattern as a mask; a third process of
removing a reaction product deposited on a wall or a bottom surface
of said opening portion; and a fourth process of rinsing an inside
of said opening portion rid of said reaction product with water;
the third process including a process of removing said reaction
product by using a first cleaning solution having relatively low
power to etch said insulator film and a second cleaning solution
having relatively high power to etch said insulator film in that
order.
2. The method of claim 1, wherein the first cleaning solution and
the second cleaning solution contain a same organic solvent.
3. The method of claim 1, wherein the first cleaning solution and
the second cleaning solution are used in a same cleaning
chamber.
4. The method of claim 1 further comprising, between the third
process and the fourth process, another process for washing the
inside of said opening portion rid of said reaction product by
using a third cleaning solution having a lower capability of
corroding said conductor pattern in the fourth process than the
second cleaning solution.
5. The method of claim 4, wherein the third cleaning solution has
relatively low power to etch said insulator film.
6. The method of claim 4, wherein the third cleaning solution is
the same as the first cleaning solution.
7. The method of claim 4, wherein the third cleaning solution
substantially has no power to etch said insulator film and
substantially has no capability of corroding said conductive
pattern in the fourth process.
8. A method for fabricating an electronic device comprising: a
first process for forming a processed film on an underlying film
formed on a substrate; a second process for forming an etched
pattern by dry etching said processed film using a mask pattern; a
third process for removing a reaction product deposited on a wall
of said etched pattern; and a fourth process for rinsing said
etched pattern or a vicinity thereof rid of said reaction product
with water; the third process containing a process for removing
said reaction product by using a first cleaning solution having
relatively low power to etch said processed film and a second
cleaning solution having relatively high power to etch said
processed film in that order.
9. The method of claim 8, wherein the first cleaning solution and
the second cleaning solution contain a same organic solvent.
10. The method of claim 8, wherein the first cleaning solution and
the second cleaning solution are used in a same cleaning
chamber.
11. The method of claim 8 further comprising, between the third
process and the fourth process, another process for washing said
etched pattern or said vicinity thereof rid of said reaction
product by using a third cleaning solution having a lower
capability of corroding said underlying film in the fourth process
than the second cleaning solution.
12. The method of claim 11, wherein the third cleaning solution has
relatively low power to etch said processed film.
13. The method of claim 11, wherein the third cleaning solution is
the same as the first cleaning solution.
14. The method of claim 11, wherein the third cleaning solution
substantially has no power to etch said processed film and
substantially has no capability of corroding said underlying film
in the fourth process.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates to a method for fabricating an
electronic device, and more specifically, to a method for removing
a reaction product deposited on walls or other portions of a
pattern formed by dry etching a processed film such as a conductor
film or an insulator film.
[0002] In the fabrication of electronic devices, a dry etching
technique is often used to form a via hole in an insulator film or
to form a conductor film into a wiring pattern. It is known that
etching gas, photoresist or a processed film causes a reaction
product (a sidewall protective film or a polymer residue) to be
deposited on walls of the via hole or the wiring pattern. The
deposition of the reaction product on the bottom surface of the via
hole formed in the insulator film would cause junction failure, an
increase in the resistance of the via contact or corrosion of the
wiring pattern (underlying wiring), thereby seriously damaging the
reliability of the electronic device.
[0003] In order to remove the reaction product, there is a cleaning
solution (hereinafter referred to as the conventional cleaning
solution) which comprises an aqueous solution of an organic solvent
and a fluorine compound having power to etch the insulator film
(Refer to Japanese Laid-Open Patent Application Nos. 7-201794 and
10-55993).
[0004] In recent years, as electronic devices are highly
micromachined, new resist materials have been introduced to
increase the etch selectivity, and new etching gases
(C.sub.5F.sub.8 and the like) with a small global warming
coefficient have been introduced to show consideration for
environmental problems. As a result, a reaction product having
different components from conventional ones is caused in higher
volume, making it difficult to remove the reaction product by using
the conventional cleaning solution.
SUMMARY OF THE INVENTION
[0005] In view of the above-mentioned problems, the object of the
present invention is to secure the removal of the reaction product
deposited on walls or other portions of an etched pattern.
[0006] In order to meet the object, the inventors of the present
invention have studied the relationship between the amount of a
fluorine compound contained in a cleaning solution and the
solution's capability of removing the reaction product.
[0007] The method for fabricating the electronic device of a first
comparative example will be described as follows with reference to
FIGS. 3(a) to 3(c) by taking as an example the case where a via
hole is formed by dry etching an insulator film on a wiring and
then the reaction product deposited on walls or other portions of
the via hole is removed by using a cleaning solution having a
relatively low content of a fluorine compound, or having relatively
low power to etch the insulator film.
[0008] As shown in FIG. 3(a), an underlying wiring 4 having a
multi-layer structure consisting of a first titanium nitride film
2A, an aluminum alloy film 3 and a second titanium nitride film 2B
was formed onto a substrate 1. After this, an insulator film 5 was
formed on the underlying wiring 4, and then a resist pattern 6
having an opening portion in the via hole formation region was
formed on the insulator film 5.
[0009] Later, the insulator film 5 and the second titanium nitride
2B were sequentially dry etched with the resist pattern 6 as a mask
so as to form a via hole 7 as shown in FIG. 3(b), which was
followed by the removal of the resist pattern 6 through plasma
ashing. At this moment, a reaction product 8 was deposited on walls
and the bottom surface of the via hole 7.
[0010] The inside of the via hole 7 was washed with the cleaning
solution having a relatively low content of a fluorine compound
such as ELM-C30-A01 (hereinafter referred to as the cleaning
solution A) manufactured by Mitsubishi Gas Chemical Co., Ltd. for
10 to 20 minutes at room temperature (23.degree. C.), and then
rinsed with water. Later, the substrate 1 was dried.
[0011] Consequently, as shown in FIG. 3(c), the portion of the
reaction product 8 that had been deposited on the bottom surface of
the via hole 7 remained unremoved. In a later process, when a
conductor film was buried into the via hole 7 to form a via
contact, and an overlying wiring was formed in such a manner as to
be connected with the underlying wiring 4 via the via contact, the
overlying wiring and the underlying wiring 4 had a junction
failure. For this reason, the resistance value of the via contact
could not be measured.
[0012] Thus, when the cleaning solution has a relatively low
content of a fluorine compound, the solution's capability of
removing the reaction product greatly relies on the ability of the
organic solvent contained in the cleaning solution to dissolve the
reaction product. Therefore, not only it takes more time to remove
the reaction product, but also it becomes difficult to remove the
product entirely.
[0013] The method for fabricating the electronic device of a second
comparative example will be described as follows with reference to
FIGS. 4(a) to 4(c) by taking as an example the case where a via
hole is formed by dry etching an insulator film on a wiring and
then the reaction product deposited on walls or other portions of
the via hole is removed by using a cleaning solution having a
relatively high content of a fluorine compound, or having
relatively high power to etch the insulator film. The processes
shown in FIGS. 4(a) and 4(b) in the second comparative example will
not be explained because they are the same as the processes shown
in FIGS. 3(a) and 3(b) in the first comparative example.
[0014] In the second comparative example, the inside of the via
hole 7 was washed with a cleaning solution having a relatively high
content of a fluorine compound such as ELM-C30-A10 (hereinafter
referred to as the cleaning solution B) manufactured by Mitsubishi
Gas Chemical Co., Ltd. for 10 to 20 minutes at room temperature
(23.degree. C.), and then rinsed with water. After this, the
substrate 1 was dried. The cleaning solution B contains about 8
times as much fluorine compound, and has 50 to 200 times as high
power to etch an insulator film as the cleaning solution A. The
etching power can be the amount of etching the same type of
insulator film in the same duration in time.
[0015] As a result, as shown in FIG. 4(c), while the reaction
product 8 was entirely removed, the portion of the insulator film 5
that was in the vicinity of the via hole 7 was also removed at the
same time. In FIG. 4(c) the broken line indicates the positions of
the walls and bottom surface of the via hole 7 formed at
predetermined dimensions.
[0016] If the inside of the via hole 7 washed with the cleaning
solution B is then rinsed with water, the cleaning solution B
diluted with the water will become capable of corroding the
conductor film contained in the underlying wiring 4, namely, the
aluminum alloy film 3. To be more specific, the ability of the
cleaning solution B to corrode the aluminum alloy film 3 during the
rinse with water, that is, the cleaning solution B's capability of
corroding the aluminum alloy film 3 in the rinse water is about 3
times as high as the cleaning solution A's capability (the maximum
value) of corroding the aluminum alloy film 3 in the rinse
water.
[0017] FIG. 5(a) is a schematic view of the strengths of streams of
water inside the via hole 7 while it is being rinsed with water
according to the method for fabricating the electronic device of
the second comparative example. The arrows "a" to "e" represent
streams of water at the respective portions inside the via hole 7,
and their lengths correspond to the strengths of the streams of
water.
[0018] FIG. 5(b) shows changes in the concentration of the cleaning
solution B inside the via hole 7 while it is being rinsed with
water according to the method for fabricating the electronic device
of the second comparative example. The changes in the concentration
of the cleaning solution B are shown in correspondence with the
streams of water indicated by the arrows "a" to "e" of FIG.
5(a).
[0019] As shown in FIG. 5(a), the streams of water become less and
less powerful as they are closer to the bottom surface of the via
hole 7. The reason for this is considered that the strengths of the
streams of water inside the via hole 7 depend on the rate of
dispersion of the water stream at the top of the via hole 7. As
shown in FIG. 5(b) the closer to the bottom surface of the via hole
7, the less the concentration of the cleaning solution B decreases,
which causes the portion of the aluminum alloy film 3 that is
exposed to the via hole 7 to be in contact with the cleaning
solution B for a long time. As a result, in addition to the
remaining portion of the reaction product 8 being removed, the
exposed portion of the aluminum alloy film 3 is corroded and
dissolved to form a hollow portion 9 beneath the insulator film 5
as shown in FIG. 4(c). This results in the formation of a hydroxide
in the vicinity of the hollow portion 9 in the aluminum alloy film
3. The via contact formed by burying a conductive film into the via
hole 7 was subjected to an acceleration test, and more
specifically, a high-temperature storage resistance increase rate
test conducted for 1000 hours at a high temperature of 200.degree.
C. to find that the rate of increase in the resistance value of the
via contact (hereinafter referred to as the rate of increase in the
via resistance) was over 10%.
[0020] The results of the test indicate that a cleaning solution
with a relatively high content of a fluorine compound makes the
insulator film which underlies the reaction product be etched so as
to make it easy to remove the reaction product; however, at the
same time, the cleaning solution causes the via hole formed in the
insulator film to grow in size and the portion of the conductor
film contained in the underlying wiring which is exposed to the via
hole to be corroded.
[0021] The present invention has been contrived based on the
above-mentioned findings. To be more specific, the first method for
fabricating the electronic device of the present invention
comprises: a first process of forming an insulator film onto a
conductive pattern formed on a substrate; a second process of
forming an opening portion in said insulator film by dry etching
said insulator film using a resist pattern as a mask; a third
process of removing a reaction product deposited on a wall or a
bottom surface of said opening portion; and a fourth process of
rinsing an inside of said opening portion rid of said reaction
product with water, the third process including a process of
removing said reaction product by using a first cleaning solution
having relatively low power to etch said insulator film and a
second cleaning solution having relatively high power to etch said
insulator film in that order.
[0022] In the first method for fabricating the electronic device,
the reaction product deposited on walls or the bottom surface of
the opening portion formed in the insulator film is removed by
using the first cleaning solution with relatively low power to etch
the insulator film and the second cleaning solution with relatively
high power to etch the insulator film in that order. In this case,
the reaction product can be partly removed by the first cleaning
solution, and then the remaining part of it can be removed by the
second cleaning solution. This can shorten the time to use the
second cleaning solution, compared with the case where the reaction
product is removed by the second cleaning solution only, which
reduces the amount of etching the insulator film. This secures the
removal of the reaction product without increasing the opening
portion in size.
[0023] In the first method of fabricating the electronic device, it
is preferable that the first cleaning solution and the second
cleaning solution contain the same organic solvent.
[0024] In this case, it becomes unnecessary to provide each
cleaning solution with an individual drain line, which realizes the
centralization of the drain lines.
[0025] In the first method of fabricating the electronic device, it
is preferable that the first cleaning solution and the second
cleaning solution are used in the same cleaning chamber.
[0026] In this case, the time required for the removal of the
reaction product can be reduced.
[0027] The first method of fabricating the electronic device
preferably further comprises, between the third process and the
fourth process, another process for washing the inside of said
opening portion rid of said reaction product by using a third
cleaning solution having a lower capability of corroding said
conductor pattern in the fourth process than the second cleaning
solution.
[0028] In this case, after the removal of the reaction product by
the second cleaning solution and before the inside of the opening
portion is rinsed with water, the second cleaning solution
remaining inside the opening portion is replaced by the third
cleaning solution. Consequently, the amount of corroding the
conductor pattern during the rinse with water can be less than in
the case where the inside of the opening portion is rinsed with
water immediately after the second cleaning solution is used, which
can decrease the size of the hollow portion formed beneath the
insulator film.
[0029] When the third cleaning solution is used, the third cleaning
solution preferably has relatively low power to etch said insulator
film.
[0030] In this case, the amount of etching the insulator film can
be reduced, so that the opening portion can be prevented from
increasing in size.
[0031] When the third cleaning solution is used, the third cleaning
solution is preferably the same as the first cleaning solution.
[0032] In this case, the number of types of the cleaning solutions
used in the cleaning process can be reduced.
[0033] When the third cleaning solution is used, it is preferable
that the third cleaning solution substantially has no power to etch
said insulator film and substantially has no capability of
corroding said conductive pattern in the fourth process.
[0034] In this case, it can be secured to prevent the conductor
pattern from being corroded during the rinse with water, while the
opening portion is prevented from increasing in size.
[0035] The second method for fabricating the electronic device of
the present invention comprises: a first process for forming a
processed film on an underlying film formed on a substrate; a
second process for forming an etched pattern by dry etching said
processed film using a mask pattern; a third process for removing a
reaction product deposited on a wall of said etched pattern; and a
fourth process for rinsing said etched pattern or a vicinity
thereof rid of said reaction product with water, the third process
containing a process for removing said reaction product by using a
first cleaning solution having relatively low power to etch said
processed film and a second cleaning solution having relatively
high power to etch said processed film in that order.
[0036] In the second method for fabricating the electronic device,
the reaction product deposited on walls of the etched pattern is
removed by using the first cleaning solution with relatively low
power to etch the processed film and the second cleaning solution
with relatively high power to etch the processed film in that
order. In this case, the reaction product can be partly removed by
the first cleaning solution, and then the remaining part of it can
be removed by the second cleaning solution. This can shorten the
time to use the second cleaning solution, compared with the case
where the reaction product is removed by the second cleaning
solution only, which reduces the amount of etching the processed
film. This secures the removal of the reaction product without
changing the size of the etched pattern.
[0037] In the second method of fabricating the electronic device,
the first cleaning solution and the second cleaning solution
preferably contain the same organic solvent.
[0038] In this case, it becomes unnecessary to provide each
cleaning solution with an individual drain line, which realizes the
centralization of the drain lines.
[0039] In the second method of fabricating the electronic device,
the first cleaning solution and the second cleaning solution are
preferably used in the same cleaning chamber.
[0040] In this case, the time required for the removal of the
reaction product can be reduced.
[0041] The second method of fabricating the electronic device
preferably further comprises, between the third process and the
fourth process, another process for washing said etched pattern or
said vicinity thereof rid of said reaction product by using a third
cleaning solution having a lower capability of corroding said
underlying film in the fourth process than the second cleaning
solution.
[0042] In this case, after the removal of the reaction product by
the second cleaning solution and before the etched pattern or its
vicinity are rinsed with water, the second cleaning solution
remaining on the etched pattern or its vicinity is replaced by the
third cleaning solution. Consequently, the amount of corroding the
underlying film during the rinse with water can be less than in the
case where the etched pattern or its vicinity is rinsed with water
immediately after the second cleaning solution is used.
[0043] When the third cleaning solution is used, the third cleaning
solution preferably has relatively low power to etch said processed
film.
[0044] In this case, the amount of etching the processed film can
be reduced, so that the etched pattern can be prevented from
changing in size.
[0045] When the third cleaning solution is used, the third cleaning
solution is preferably the same as the first cleaning solution.
[0046] In this case, the number of types of the cleaning solutions
used in the cleaning process can be reduced.
[0047] When the third cleaning solution is used, it is preferable
that the third cleaning solution substantially has no power to etch
said processed film and substantially has no capability of
corroding said underlying film in the fourth process.
[0048] In this case, it can be secured to prevent the underlying
film from being corroded during the rinse with water, while the
etched pattern is prevented from changing in size.
BRIEF DESCRIPTION OF THE DRAWINGS
[0049] FIGS. 1(a) to 1(d) are cross sectional views showing the
processes of the method for fabricating the electronic device of
the first embodiment of the present invention.
[0050] FIGS. 2(a) to 2(d) are cross sectional views showing the
processes of the method for fabricating the electronic device of
the second embodiment of the present invention.
[0051] FIGS. 3(a) to 3(c) are cross sectional views showing the
processes of the method for fabricating the electronic device of
the first comparative example.
[0052] FIGS. 4(a) to 4(c) are cross sectional views showing the
processes of the method for fabricating the electronic device of
the second comparative example.
[0053] FIG. 5(a) is a cross sectional view showing the strengths of
streams of water inside the via hole while the inside of the via
hole is being rinsed with water in accordance with the method for
fabricating the electronic device of the second comparative
example, and FIG. 5(b) is a view showing changes in the
concentration of the cleaning solution inside the via hole while
the inside of the via hole is being rinsed with water in accordance
with the method for fabricating the electronic device of the second
comparative example.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
EMBODIMENT 1
[0054] The method for fabricating the electronic device of the
first embodiment will be described as follows with reference to
FIGS. 1(a) to 1(d).
[0055] First, as shown in FIG. 1(a), an underlying wiring 14 having
a multi-layer structure consisting of a first titanium nitride film
12A, an aluminum alloy film 13 and a second titanium nitride film
12B is formed onto a substrate 11. After this, an insulator film 15
is formed on the underlying wiring 14, and a resist pattern 16
having an opening portion in the via hole formation region is
formed on the insulator film 15.
[0056] Later, the insulator film 15 and a second titanium nitride
film 12B are sequentially dry etched by using the resist pattern 16
as a mask so as to form a via hole 17 as shown in FIG. 1(b), which
is followed by the removal of the resist pattern 16 through plasma
ashing.
[0057] At this moment, a reaction product 18 is deposited on walls
and the bottom surface of the via hole 17.
[0058] In order to remove the reaction product 18, the inside of
the via hole 17 is washed with a first cleaning solution having
relatively low power to etch the insulator film 15, or having a
relatively low content of a fluorine compound such as ELM-C30-A01
(hereinafter referred to as the cleaning solution A) manufactured
by Mitsubishi Gas Chemical Co., Ltd. for 10 to 20 minutes at room
temperature or 23.degree. C.
[0059] Since the first cleaning solution has relatively low power
to etch the insulator film 15, the reaction product 18 is removed
from the via hole 17 except the bottom surface of the via hole 17
and its vicinity as shown in FIG. 1(c) without causing an increase
in the size of the via hole 17.
[0060] In order to remove the remaining reaction product 18, the
inside of the via hole 17 is washed with a second cleaning solution
having relatively high power to etch the insulator film 15, or
having a relatively high content of a fluorine compound such as
ELM-C30-A10 (herein after referred to as the cleaning solution B)
manufactured by Mitsubishi Gas Chemical Co., Ltd. at room
temperature or 23.degree. C. for 30 seconds to 5 minutes in the
cleaning chamber (not shown) where the first cleaning solution has
been used. The cleaning solution B contains about 8 times as much
fluorine compound, and has 50 to 200 times as high power to etch
the insulator film 15 as the cleaning solution A. The etching power
can be the amount of etching the same type of insulator film in the
same duration in time.
[0061] In this case, the reaction product 18 is partly removed by
using the first cleaning solution having relatively low power to
etch the insulator film 15, and then the remaining part of it is
removed by using the second cleaning solution having relatively
high power to etch the insulator film 15. This shortens the time to
use the second cleaning solution, compared with the case where the
reaction product 18 is removed by the second cleaning solution
only. As a result, as shown in FIG. 1(d), the amount of etching the
insulator film 15 can be reduced, which secures the removal of the
reaction product 18 without increasing the via hole 17 in size.
[0062] If the inside of the via hole 17 washed with the second
cleaning solution or the cleaning solution B were rinsed with water
immediately, the cleaning solution B diluted by the water during
the rinse would become capable of corroding the conductor film
contained in the underlying wiring 14, namely, the aluminum alloy
film 13. To be more specific, the ability of the cleaning solution
B to corrode the aluminum alloy film 13 during the rinse with
water, that is, the cleaning solution B's capability of corroding
the aluminum alloy film 13 in rinse water, is about 3 times as high
as the cleaning solution A's capability (the maximum value) of
corroding the aluminum alloy film 13 in rinse water.
[0063] In order to avoid this problem, in the present embodiment,
after the reaction product 18 is removed with the second cleaning
solution and before the inside of the via hole 17 is rinsed with
water, the second cleaning solution or the cleaning solution B
remaining inside the via hole 17 is replaced by a third cleaning
solution having a lower capability of corroding the aluminum alloy
film 13 during the rinse with water than the second cleaning
solution (the cleaning solution B). To be more specific, the inside
of the via hole 17 is washed with the cleaning solution A identical
with the first cleaning solution as the third cleaning solution at
room temperature or 23.degree. C. for 30 seconds to 10 minutes in
the cleaning chamber where the first and second cleaning solutions
have been used. In this case, the aluminum alloy film 13 can be
less corroded during the rinse with water than in the case where
the inside of the via hole 17 is rinsed with water immediately
after the second cleaning solution is used. Later, after the inside
of the via hole 17 is rinsed with water in the cleaning chamber
where the first to third cleaning solutions have been used, the
substrate 11 is dried.
[0064] As described hereinbefore, in the present embodiment the
reaction product 18 deposited on walls or the bottom surface of the
via hole 17 formed in the insulator film 15 is removed by using the
first cleaning solution with relatively low power to etch the
insulator film 15 and the second cleaning solution with relatively
high power to etch the insulator film 15 in that order. In this
case, the reaction product 18 can be partly removed by the first
cleaning solution, and then the remaining part of it can be removed
by the second cleaning solution. This can shorten the time to use
the second cleaning solution, compared with the case where the
reaction product 18 is removed by the second cleaning solution
only, thereby reducing the amount of etching the insulator film 15.
This secures the removal of the reaction product 18 without
increasing the via hole 17 in size.
[0065] Furthermore, after the reaction product 18 is removed with
the first and second cleaning solutions and before the inside of
the via hole 17 is rinsed with water, the inside of the via hole 17
is washed with a third cleaning solution having a lower capability
of corroding the aluminum alloy film 13 contained in the underlying
wiring 14 during the rinse with water than the second cleaning
solution, thereby replacing the second cleaning solution remaining
inside the via hole 17 by the third cleaning solution. As a result,
the aluminum alloy film 13 is less corroded than in the case where
the inside of the via hole 17 is rinsed with water immediately
after the second cleaning solution is used, which decreases the
size of the hollow portion 19 formed beneath the insulator film 15.
Moreover, a less amount of hydroxide can be formed in the vicinity
of the hollow portion 19 in the aluminum alloy film 13. As a
result, an acceleration test (high-temperature storage resistance
increase rate test) applied to the via contact formed by burying a
conductor film into the via hole 17 has indicated that an increase
in the resistance value of the via contact is prevented.
[0066] In the present embodiment, the use of the cleaning solution
A which is identical with the first cleaning solution and which has
relatively low power to etch the insulator film 15 as the third
cleaning solution can reduce not only the number of types of the
cleaning solutions used in the cleaning process but also the amount
of etching the insulator film 15 so as to prevent an increase in
the size of the via hole 17.
[0067] Table 1 shows the results of comparisons among the first
embodiment, the first comparative example and the second
comparative example (refer to "SUMMARY OF THE INVENTION") with
respect to the capabilities of removing the reaction product,
preventing an increase in the size of the via hole, preventing the
formation of the hollow portion, and preventing an increase in the
resistance value of the via contact at the high-temperature storage
resistance increase rate test (200.degree. C., 1000 hours).
1 TABLE 1 prevention of the rate of increase in the via resistance
in the high-temper- prevention prevention ature removal of of an of
the storage a deposited increase in formation resistance reaction
the size of of a hollow increase product a via hole portion rate
test Embodiment 1 .largecircle. .largecircle. .DELTA. .DELTA.
Comparative X .largecircle. --.sup.(1) --.sup.(2) Example 1
Comparative .largecircle. X X X Example 2
[0068] remained unremoved.
[0069] Prevention of an Increase in the Size of a Via Hole
[0070] .largecircle.: the difference in size of the via hole
between before and after the cleaning was less than 30 nm.
[0071] X: the difference in size of the via hole between before and
after the cleaning was 30 nm or more.
[0072] Prevention of the Formation of a Hollow Portion
[0073] .largecircle.: no formation of the hollow portion was
observed.
[0074] .DELTA.: a relatively small hollow portion was observed.
[0075] X: a relatively large hollow portion was observed.
[0076] (1) no formation of the hollow portion was observed because
the deposited reaction product partly remained unremoved.
[0077] Prevention of the Rate of Increase in the Via Resistance in
the High-temperature storage Resistance Increase Rate Test
[0078] .largecircle.: the rate of increase in the via resistance
was less than 2%.
[0079] .DELTA.: the rate of increase in the via resistance was not
less than 2% nor more than 10%.
[0080] X: the rate of increase in the via resistance was more than
10%.
[0081] (2) the via resistance could not be measured because the
deposited reaction product partly remained unremoved.
[0082] As Table 1 shows, the method for fabricating the electronic
device of the first embodiment has entirely removed the reaction
product 18 deposited on walls and the bottom surface of the via
hole 17, and also restricted an increase in the size of the via
hole 17 within less than 30 nm. On the other hand, this method has
caused the formation of a relatively small-sized hollow portion 19,
and had a rate of increase in the via resistance of not less than
2% nor more than 10% in the high-temperature storage resistance
increase rate test.
[0083] The conductor film contained in the underlying wiring 14 in
the first embodiment is composed of a multi-layered film comprising
the aluminum alloy film 13 which has a relatively low corrosion
resistance to, or is easily corroded by the fluorine compound
contained in the first or the second cleaning solution. However,
this multi-layered film could be replaced by a single-layered
aluminum alloy film, a single-layered or a multi-layered aluminum
film, or another metallic film not easily corroded by the fluorine
compound.
[0084] The cleaning solution A used as the first cleaning solution
in the first embodiment has a relatively low content of a fluorine
compound having power to etch the insulator film 15; however, the
first cleaning solution could be another cleaning solution having
relatively low power to etch the insulator film 15.
[0085] The cleaning solution B used as the second cleaning solution
in the first embodiment has a relatively high content of a fluorine
compound having power to etch the insulator film 15; however, the
second cleaning solution could be another cleaning solution having
relatively high power to etch the insulator film 15.
[0086] The cleaning solution B used as the second cleaning solution
in the first embodiment has relatively high power to etch the
insulator film 15 and a relatively high capability of corroding the
conductor film contained in the underlying wiring 14 during the
rinse with water; however, the second cleaning solution could be
another cleaning solution having relatively high power to etch the
insulator film 15 and having a relatively low capability of
corroding the conductor film contained in the underlying wiring 14
during the rinse with water. In this case, when the inside of the
via hole 17 is rinsed with water immediately after the second
cleaning solution is used, the conductor film contained in the
underlying wiring 14 can be less corroded during the rinse with
water. As a result, the third cleaning solution becomes
unnecessary, thereby reducing the time required for the entire
cleaning process.
[0087] In the first embodiment, when the cleaning solution having a
relatively high capability of corroding the conductor film
contained in the underlying wiring 14 during the rinse with water
is used as the second cleaning solution, the process where the
third cleaning solution is used can be omitted unless the
performance of the electronic device to be fabricated is not
influenced by deterioration of the conductor film contained in the
underlying wiring 14 or an increase in the resistance value of the
via contact formed by burying a conductor film into the via hole
17. The omission of the process can shorten the time required for
the entire cleaning process.
[0088] The third cleaning solution in the first embodiment is
identical with the first cleaning solution, namely, the cleaning
solution A; however, the third cleaning solution could be another
cleaning solution with a lower capability of corroding the
conductor film contained in the underlying wiring 14 during the
rinse with water than the second cleaning solution. In this case,
it is preferable that the third cleaning solution has relatively
low power to etch the insulator film 15.
[0089] The first and second cleaning solutions are used at room
temperature or 23.degree. C. in the first embodiment; however, they
could be used in a range of 18.degree. to 25.degree. C. If the use
of the first or the second cleaning solution in a range of
18.degree. to 25.degree. C. seriously decreases the rate of
removing the reaction product 18, these solutions could be heated
to around 35.degree. to 60.degree. C.
[0090] In the first embodiment, it is preferable that the
temperatures and the duration in time to use the first to third
cleaning solutions are determined by taking the state of the
reaction product 18, or the type of the conductive film contained
in the underlying wiring 14 into consideration.
[0091] In the first embodiment, the first to third cleaning
solutions preferably contain the same organic solvent. This makes
it unnecessary to provide each cleaning solution with an individual
drain line, thereby centralizing the drain lines.
[0092] Cleaning methods with the first to third cleaning solutions
available in the first embodiment include a batch type cleaning
method where the substrate 11 or the substrate to be processed is
soaked in a cleaning solution and a single wafer type or a batch
type cleaning method where a cleaning solution is sprayed like a
shower, discharged or dropped continuously or intermittently to the
substrate to be processed while the substrate is being rotated.
[0093] In the first embodiment, the first to third cleaning
solutions are preferably used in the same cleaning chamber. In that
case, the time required for the entire cleaning process can be
shortened, and the time can be further shortened if the process of
rinsing the inside of the via hole 17 with water is done in the
cleaning chamber where the first to third cleaning solutions have
been used.
[0094] The first embodiment deals with the case where a via hole is
formed by dry etching the insulator film formed on the wiring and
then the reaction product deposited on walls or the bottom surface
of the via hole is removed. In addition to this case, there are
such cases that a contact hole is formed by dry etching the
insulator film formed on the gate electrode of a MOS transistor and
then the reaction product deposited on walls or the bottom surface
of the contact hole is removed, and that a wiring pattern is formed
by dry etching the conductor film formed on the insulator film and
then the reaction product deposited on walls of the wiring pattern
or in the vicinity of the wiring pattern is removed. In order to
remove the reaction product deposited on walls or the bottom
surface of the contact hole, it is preferable to use the first
cleaning solution having relatively low power to etch the insulator
film in which the contact hole is formed and then the second
cleaning solution having relatively high power to etch the
insulator film in that order. On the other hand, in order to remove
the reaction product deposited on walls of the wiring pattern or in
the vicinity of the wiring pattern, it is preferable to use the
first cleaning solution having relatively low power to etch the
conductive film contained in the wiring pattern and then the second
cleaning solution having relatively high power to etch the
conductive film in that order.
EMBODIMENT 2
[0095] The method for fabricating the electronic device of the
second embodiment will be described with reference to FIGS. 2(a) to
2(d).
[0096] First, as shown in FIG. 2(a), an underlying wiring 24 having
a multi-layer structure consisting of a first titanium nitride film
22A, an aluminum alloy film 23 and a second titanium nitride film
22B is formed onto a substrate 21. After this, an insulator film 25
is formed on the underlying wiring 24, and a resist pattern 26
having an opening portion in the via hole formation region is
formed on the insulator film 25.
[0097] Later, the insulator film 25 and a second titanium nitride
film 22B are sequentially dry etched by using the resist pattern 26
as a mask so as to form a via hole 27 as shown in FIG. 2(b), and
then the resist pattern 26 is removed through plasma ashing.
[0098] At this moment, a reaction product 28 is deposited on walls
and the bottom surface of the via hole 27.
[0099] In order to remove the reaction product 28, the inside of
the via hole 27 is washed with a first cleaning solution having
relatively low power to etch the insulator film 25, or having a
relatively low content of a fluorine compound such as ELM-C30-A01
(hereinafter referred to as the cleaning solution A) manufactured
by Mitsubishi Gas Chemical Co., Ltd. for 10 to 20 minutes at room
temperature or 23.degree. C.
[0100] Since the first cleaning solution has relatively low power
to etch the insulator film 25, the reaction product 28 is removed
from the via hole 27 except the bottom surface of the via hole 27
and its vicinity as shown in FIG. 2(c) without causing an increase
in the size of the via hole 27.
[0101] In order to remove the remaining reaction product 28, the
inside of the via hole 27 is washed with a second cleaning solution
having relatively high power to etch the insulator film 25, or
having a relatively high content of a fluorine compound such as
ELM-C30-A10 (hereinafter referred to as the cleaning solution B)
manufactured by Mitsubishi Gas Chemical Co., Ltd. at room
temperature or 23.degree. C. for 30 seconds to 5 minutes in the
cleaning chamber (not shown) where the first cleaning solution has
been used. The cleaning solution B contains about 8 times as much
fluorine compound, and has 50 to 200 times as high power to etch
the insulator film 25 as the cleaning solution A. The etching power
can be the amount of etching the same type of insulator film in the
same duration in time.
[0102] In this case, the reaction product 28 is partly removed by
using the first cleaning solution having relatively low power to
etch the insulator film 25, and then the remaining part of it is
removed by using the second cleaning solution having relatively
high power to etch the insulator film 25. This shortens the time to
use the second cleaning solution, compared with the case where the
reaction product 28 is removed by the second cleaning solution
only. As a result, as shown in FIG. 2(d), the amount of etching the
insulator film 25 can be reduced, which secures the removal of the
reaction product 28 without increasing the via hole 27 in size.
[0103] If the inside of the via hole 27 washed with the second
cleaning solution or the cleaning solution B were rinsed with water
immediately, the cleaning solution B diluted by the water during
the rinse would become capable of corroding the conductor film
contained in the underlying wiring 24, namely, the aluminum alloy
film 23. To be more specific, the ability of the cleaning solution
B to corrode the aluminum alloy film 23 during the rinse with
water, that is, the cleaning solution B's capability of corroding
the aluminum alloy film 23 in rinse water, is about 3 times as high
as the cleaning solution A's capability (the maximum value) of
corroding the aluminum alloy film 23 in rinse water.
[0104] In order to avoid this problem, in the present embodiment,
after the reaction product 28 is removed with the second cleaning
solution and before the inside of the via hole 27 is rinsed with
water, the second cleaning solution or the cleaning solution B
remaining inside the via hole 27 is replaced by a third cleaning
solution having substantially no power to etch the insulator film
25 and having substantially no capability of corroding the aluminum
alloy film 23 during the rinse with water. To be more specific, the
inside of the via hole 27 is washed with a cleaning solution having
an organic solvent content of 1 to 60% in weight such as
N,N-dimethylformamide (having no content of a fluorine compound or
the like with power to etch the insulator film 25) as the third
cleaning solution at room temperature or 23.degree. C. for 30
seconds to 10 minutes in the cleaning chamber where the first and
second cleaning solutions have been used. In this case, the
aluminum alloy film 23 can be less corroded during the rinse with
water than in the case where the inside of the via hole 27 is
rinsed with water immediately after the second cleaning solution is
used. Later, after the inside of the via hole 27 is rinsed with
water in the cleaning chamber where the first to third cleaning
solutions have been used, the substrate 21 is dried.
[0105] As described hereinbefore, in the present embodiment the
reaction product 28 deposited on walls or the bottom surface of the
via hole 27 formed in the insulator film 25 is removed by using the
first cleaning solution with relatively low power to etch the
insulator film 25 and the second cleaning solution with relatively
high power to etch the insulator film 25 in that order. In this
case, the reaction product 28 can be partly removed by the first
cleaning solution, and then the remaining part of it can be removed
by the second cleaning solution. This can shorten the time to use
the second cleaning solution, compared with the case where the
reaction product 28 is removed by the second cleaning solution
only, thereby reducing the amount of etching the insulator film 25.
This secures the removal of the reaction product 28 without
increasing the via hole 27 in size.
[0106] Furthermore, after the reaction product 28 is removed with
the first and second cleaning solutions and before the inside of
the via hole 27 is rinsed with water, the inside of the via hole 27
is washed with a third cleaning solution having substantially no
capability of corroding the aluminum alloy film 23 contained in the
underlying wiring 24 during the rinse with water, thereby replacing
the second cleaning solution remaining inside the via hole 27 by
the third cleaning solution. As a result, the aluminum alloy film
23 is prevented from being corroded during the rinse with water,
which avoids the formation of a hollow portion beneath the
insulator film 25. Moreover, the aluminum alloy film 23 is
substantially kept from being corroded. As a result, an
acceleration test (high-temperature storage resistance increase
rate test) applied to the via contact formed by burying a conductor
film into the via hole 27 has indicated that an increase in the
resistance value of the via contact is securely prevented.
[0107] In the present embodiment, the use of the cleaning solution
having substantially no power to etch the insulator film 25 as the
third cleaning solution can prevent the insulator film 25 from
being etched so as to prevent an increase in the size of the via
hole 27.
[0108] Table 2 shows the results of comparisons among the second
embodiment, the first comparative example and the second
comparative example (refer to "SUMMARY OF THE INVENTION") with
respect to the capabilities of removing the reaction product,
preventing an increase in the size of the via hole, preventing the
formation of the hollow portion, and preventing an increase in the
resistance value of the via contact at the high-temperature storage
resistance increase rate test (200.degree. C., 1000 hours).
2 TABLE 2 prevention of the rate of incease in the via resistance
in the high-temper- prevention prevention ature removal of of an of
the storage a deposited increase in formation resistance reaction
the size of of a hollow increase product a via hole portion rate
test Embodiment 2 .largecircle. .largecircle. .largecircle.
.largecircle. Comparative X .largecircle. --.sup.(1) --.sup.(2)
Example 1 Comparative .largecircle. X X X Example 2
[0109] .largecircle.: the deposited reaction product was completely
removed.
[0110] X: the major portion of the deposited reaction product
remained unremoved.
[0111] Prevention of an Increase in the Size of a Via Hole
[0112] .largecircle.: the difference in size of the via hole
between before and after the cleaning was less than 30 nm.
[0113] X: the difference in size of the via hole between before and
after the cleaning was 30 nm or more.
[0114] Prevention of the Formation of a Hollow Portion
[0115] .largecircle.: no formation of the hollow portion was
observed.
[0116] .DELTA.: a relatively small hollow portion was observed.
[0117] X: a relatively large hollow portion was observed.
[0118] (1) no formation of the hollow portion was observed because
the deposited reaction product partly remained unremoved.
[0119] Prevention of the Rate of Increase in the Via Resistance in
the High-temperature Storage Resistance Increase Rate Test
[0120] .largecircle.: the rate of increase in the via resistance
was less than 2%.
[0121] .DELTA.: the rate of increase in the via resistance was not
less than 2% nor more than 10%.
[0122] X: the rate of increase in the via resistance was more than
10%.
[0123] (2) the via resistance could not be measured because the
deposited reaction product partly remained unremoved.
[0124] As Table 2 shows, the method for fabricating the electronic
device of the second embodiment has entirely removed the reaction
product 28 deposited on walls and the bottom surface of the via
hole 27, and also restricted an increase in the size of the via
hole 27 within less than 30 nm. Furthermore, this method has
developed substantially no hollow portion, and had a rate of
increase in the via resistance of less than 2% in the
high-temperature storage resistance increase rate test.
[0125] The conductor film contained in the underlying wiring 24 in
the second embodiment is composed of a multi-layered film
comprising the aluminum alloy film 23 which has a relatively low
corrosion resistance to, or is easily corroded by the fluorine
compound contained in the first or the second cleaning solution.
However, this multi-layered film could be replaced by a
single-layered aluminum alloy film, a single-layered or a
multi-layered aluminum film, or another metallic film not easily
corroded by the fluorine compound.
[0126] The cleaning solution A used as the first cleaning solution
in the second embodiment has a relatively low content of a fluorine
compound having power to etch the insulator film 25; however, the
first cleaning solution could be another cleaning solution having
relatively low power to etch the insulator film 25.
[0127] The cleaning solution B used as the second cleaning solution
in the second embodiment has a relatively high content of a
fluorine compound having power to etch the insulator film 25;
however, the second cleaning solution could be another cleaning
solution having relatively high power to etch the insulator film
25.
[0128] The cleaning solution B used as the second cleaning solution
in the second embodiment has relatively high power to etch the
insulator film 25 and a relatively high capability of corroding the
conductor film contained in the underlying wiring 24 during the
rinse with water; however, the second cleaning solution could be
another cleaning solution having relatively high power to etch the
insulator film 25 and having substantially no capability of
corroding the conductor film contained in the underlying wiring 24
during the rinse with water. In this case, when the inside of the
via hole 27 is rinsed with water immediately after the second
cleaning solution is used, the conductor film contained in the
underlying wiring 24 can be prevented from being corroded during
the rinse with water. As a result, the third cleaning solution
becomes unnecessary, thereby reducing the time required for the
entire cleaning process.
[0129] In the second embodiment, when the cleaning solution having
a relatively high capability of corroding the conductor film
contained in the underlying wiring 24 during the rinse with water
is used as the second cleaning solution, the process where the
third cleaning solution is used can be omitted unless the
performance of the electronic device to be fabricated is not
influenced by deterioration of the conductor film contained in the
underlying wiring 24 or an increase in the resistance value of the
via contact formed by burying a conductor film into the via hole
27. The omission of the process can shorten the time required for
the entire cleaning process.
[0130] As the organic solvent contained in the third cleaning
solution, 1 to 60% in weight of N,N-dimethylformamide is used in
the second embodiment. Besides this material, the organic solvent
could be 1 to 60% in weight, and preferably 5 to 50% in weight of
such organic solvents as an amide group including formamide,
N-methylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone;
a lactone group including .gamma.-butyrolactone, an alcohol group
including methanol, ethanol, isopropanol, and ethylene glycol; an
ester group including methyl acetate, ethyl acetate, butyl acetate,
methyl lactate, and ethyl lactate; a glycol ether group including
ethylene glycol monobutyl ether, diethylene glycol monomethyl
ether, and diethylene glycol monoethyl ether, and a nitrile group
including acetonitrile, propionitrile, and butyronitrile.
[0131] The first and second cleaning solutions are used at room
temperature or 23.degree. C. in the second embodiment; however,
they could be used in a range of 18.degree. to 25.degree. C. If the
use of the first or the second cleaning solution in a range of
18.degree. to 25.degree. C. seriously decreases the rate of
removing the reaction product 28, these solutions could be heated
to around 35.degree. to 60.degree. C.
[0132] In the second embodiment, it is preferable that the
temperatures and the duration in time to use the first to third
cleaning solutions are determined by taking the state of the
reaction product 28, or the type of the conductive film contained
in the underlying wiring 24 into consideration.
[0133] In the second embodiment, the first to third cleaning
solutions preferably contain the same organic solvent. This makes
it unnecessary to provide each cleaning solution with an individual
drain line, thereby centralizing the drain lines.
[0134] Cleaning methods with the first to third cleaning solutions
available in the second embodiment include a batch type cleaning
method where the substrate 21 or the substrate to be processed is
soaked in a cleaning solution and a single wafer type or a batch
type cleaning method where a cleaning solution is sprayed like a
shower, discharged or dropped continuously or intermittently to the
substrate to be processed while the substrate is being rotated.
[0135] In the second embodiment, the first to third cleaning
solutions are preferably used in the same cleaning chamber. In that
case, the time required for the entire cleaning process can be
shortened, and the time can be further shortened if the process of
rinsing the inside of the via hole 27 with water is done in the
cleaning chamber where the first to third cleaning solutions have
been used.
[0136] The second embodiment deals with the case where a via hole
is formed by dry etching the insulator film formed on the wiring
and then the reaction product deposited on walls or the bottom
surface of the via hole is removed. In addition to this case, there
are such cases that a contact hole is formed by dry etching the
insulator film formed on the gate electrode of a MOS transistor and
then the reaction product deposited on walls or the bottom surface
of the contact hole is removed, and that a wiring pattern is formed
by dry etching the conductor film formed on the insulator film and
then the reaction product deposited on walls of the wiring pattern
or in the vicinity of the wiring pattern is removed. In order to
remove the reaction product deposited on walls or the bottom
surface of the contact hole, it is preferable to use the first
cleaning solution having relatively low power to etch the insulator
film in which the contact hole is formed and then the second
cleaning solution having relatively high power to etch the
insulator film in that order. On the other hand, in order to remove
the reaction product deposited on walls of the wiring pattern or in
the vicinity of the wiring pattern, it is preferable to use the
first cleaning solution having relatively low power to etch the
conductive film contained in the wiring pattern and then the second
cleaning solution having relatively high power to etch the
conductive film in that order.
* * * * *