Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Of specified material other than unalloyed aluminum
Reexamination Certificate
2001-01-04
2002-08-13
Ho, Hoai V. (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Of specified material other than unalloyed aluminum
C257S751000, C438S622000
Reexamination Certificate
active
06433432
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and to a method of manufacturing the same and, more particularly, to a semiconductor device having a structure in which plugs or wirings are connected onto a metal pattern buried in a fluorine-containing insulating film and to a method of manufacturing the same.
2. Description of the Prior Art
In recent LSI, in order to achieve the higher speed of LSI, the insulating film between wirings is made of the low dielectric constant material. As such the low dielectric constant material, there is a silicon oxide film in which fluorine or carbon is contained, for example.
The step of connecting a pad to a damascene structure metal wiring formed in an interlayer insulating film containing fluorine will now be explained.
First, as shown in
FIG. 1A
, a first silicon nitride film
103
is formed on an insulating film
102
made of silicon oxide, etc., formed on a semiconductor substrate
101
, and then a first silicon oxide fluoride (SiOF) film
104
is formed thereon.
Then, as shown in
FIG. 1B
, a wiring trench (recess)
105
is formed by patterning the first SiOF film
104
and the first silicon nitride film
103
. In this case, the first silicon nitride film
103
is used as an etching stopper in etching the first SiOF film
104
. Then, a first barrier metal film
106
made of tantalum nitride and a first copper film
107
are formed in sequence on an inner surface of the wiring trench
105
and the first SiOF film
104
. Then, as shown in
FIG. 1C
, the first copper film
107
on the first SiOF film
104
and the first barrier metal film
106
are left only in the wiring trench
105
by polishing them by virtue of the CMP method. The first copper film
107
and the first barrier metal film
106
in the wiring trench
105
are used as a wiring
108
.
Then, a surface of the wiring
108
is cleaned by the chemicals. Then, as shown in
FIG. 1D
, a second silicon nitride film
109
and a second SiOF film
110
are formed in sequence on the wiring
108
and the first SiOF film
104
. Then, by patterning the second SiOF film
110
and the second silicon nitride film
109
in sequence, a plurality of holes
110
a
are formed in the lower portion of the second SiOF film
110
and also a pad trench
110
b
is formed on the holes
110
a.
Then, as shown in
FIG. 1E
, a second barrier metal layer
111
is formed on inner surfaces of a plurality of holes
110
a,
an inner surface of the pad trench
110
b
and an upper surface of the second SiOF film
110
, and then a second copper film
112
is buried in the holes
110
a
and the pad trench
110
b.
Then, the second copper film
112
and the second barrier metal layer
111
are removed from an upper surface of the second SiOF film
110
by polishing them by virtue of the CMP method. Accordingly, the second copper film
112
left in the pad trench
110
b
is used as a pad electrode
114
, and the second copper film
112
left in the holes
110
a
are used as plugs
113
.
After this, as shown in
FIG. 1F
, a third silicon nitride film
112
is formed on the pad electrode
114
and the second SiOF film
110
, and then a protection insulating film
116
is formed on the third silicon nitride film
112
.
However, according to the above steps, as shown in
FIG. 2
, the plugs
113
are peeled off from the upper surface of the wiring
108
after the protection insulating film
116
is formed. In contrast, since such peeling-off of the plugs
113
is not caused when the silicon oxide film is formed in place of the first SiOF film
104
, it may be supposed that fluorine contained in the first SiOF film
104
participates in the peeling-off of the plugs
113
.
By the way, the event that the metal is degraded when the metal is formed on the fluorine-containing insulating film is set forth in Patent Application Publication (KOKAI) Hei 10-144793. However, since there is no recitation that the plugs are peeled off from the polished metal wiring, the technology set forth in the above Publication cannot be applied to prevent the peeling-off of the plugs from the metal wiring.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a semiconductor device capable of maintaining good connection between a metal film buried in a trench of a fluorine-containing insulating film and another metal film connected to such metal film, and a method of manufacturing the same.
According to the present invention, after the trench is formed in the fluorine-containing insulating film, then the metal film is formed in the trench and on the fluorine-containing insulating film, and then the metal film is polished to remove from the fluorine-containing insulating film but leave in the trench, the fluorine stuck onto the surface of the metal film can be reduced.
Accordingly, after the fluorine-noncontaining insulating film, e.g., the silicon nitride film, the silicon carbide film, or the silicon oxide film is formed on the metal film buried in the trench and then the metal plugs that penetrate the fluorine-noncontaining insulating film are connected to the upper surface of the metal film, the situation that the fluorine-noncontaining insulating film is never peeled off from the metal film or the metal plugs are never separated from the metal film can be eliminated. Thus, the adhesiveness between the fluorine-noncontaining insulating film and the metal film can be improved and the connection between the metal film and the metal plugs is good.
If an amount of the fluorine on the surface of the metal film buried in the trench in this manner is reduced to less than 60% of that obtained when the surface of the copper wiring is cleaned, more preferably, less than 3.9 atom %, the adhesiveness between the metal film and the metal plugs or the metal film and the overlying fluorine-noncontaining insulating film can be improved.
REFERENCES:
patent: 5334552 (1994-08-01), Homma
patent: 6046502 (2000-04-01), Matsuno
patent: 6121162 (2000-09-01), Endo
patent: 6127099 (2000-10-01), Shinohara
patent: 10-144793 (1998-05-01), None
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