Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching
Reexamination Certificate
2000-12-05
2002-09-17
Nguyen, Ha Tran (Department: 2812)
Semiconductor device manufacturing: process
Chemical etching
Vapor phase etching
C438S745000, C438S749000, C134S001200, C134S001300
Reexamination Certificate
active
06451707
ABSTRACT:
BACKGROUND OF THE INVENTION
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.
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.
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).
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
5
F
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
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.
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.
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.
As shown in FIG.
3
(
a
), an underlying wiring
4
having a multi-layer structure consisting of a first titanium nitride film
2
A, an aluminum alloy film
3
and a second titanium nitride film
2
B 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
.
Later, the insulator film
5
and the second titanium nitride
2
B 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
.
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° C.), and then rinsed with water. Later, the substrate
1
was dried.
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.
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.
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.
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° 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.
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.
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.
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.
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
).
As shown
Miyoshi Yuichi
Nagai Toshihiko
Nguyen Ha Tran
Studebaker Donald P.
LandOfFree
Method of removing reaction product due to plasma ashing of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of removing reaction product due to plasma ashing of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of removing reaction product due to plasma ashing of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2826053