Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – By reaction with substrate
Reexamination Certificate
2002-02-11
2004-09-07
Fourson, George (Department: 2823)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
By reaction with substrate
C438S687000, C438S798000
Reexamination Certificate
active
06787480
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method of a semiconductor device which comprises the steps of forming a copper-containing film, and more particularly to a manufacturing method of a semiconductor device having an interconnection, an interconnection connecting plug, a pad section or such, made of copper or a copper alloy.
In recent years, copper and copper alloys have been widely used as the material for interconnections and connecting plugs to achieve higher speed operations in the elements. With these metals utilized, the interconnections and the likes are generally formed by the damascene method.
FIG. 5
is a series of views illustrating the steps of a conventional method of forming a copper interconnection. Now, this method is described below. First, as shown in FIG.
5
(
a
), after an insulating film
10
and an interlayer insulating film
12
are formed, in this order, on a semiconductor substrate (not shown in the drawings), an interconnection trench is set within the interlayer insulating film
12
, and thereon a barrier metal film
14
made of Ta; TaN or such and a seed copper film
15
are formed, in succession, and then a copper film
16
is formed by the plating method.
The semiconductor wafer
1
in this state is subjected to the chemical mechanical polishing (CMP) and copper lying outside of the interconnection trench is removed, while copper lying inside of the trench is left as it is, whereby a copper interconnection
17
is formed. At this, copper oxide
21
is produced on the copper interconnection
17
, and a carboxylic acid cleaning is performed (FIG.
5
(
b
)) for removing this copper oxide
21
. In this way, copper oxide which may cause an increase in interconnection resistance or contact resistance can be eliminated (FIG.
5
(
c
)). After that, as shown in FIG.
5
(
d
), a silicon nitride film
18
is formed and thereon an interlayer insulating film
19
is formed.
In such steps of forming a copper interconnection, it is essential to remove copper oxide which is formed on the copper surface so that the electrical resistance may be prevented from increasing. While copper oxide is removed with carboxylic acid in the above method, other methods such as a method by a plasma treatment with a reducing gas are also known. For example, in a method described in “TDDB Improvement in Cu Metallization under Bias Stress” by J. Noguchi et al. (IEEE 38
th
Annual International Reliability Physics Symposium, San Jose, Calif. 2000, pp. 339-343), a plasma treatment with a hydrogen or ammonia gas is carried out to achieve the reduction of CuO which is formed on the surface of the copper interconnection to Cu, along with the formation of a Cu layer thereon. Moreover, it is described therein that once CuN is formed, this may function as a protective film, and when a copper-diffusion prevention film of SiN or the like is grown thereon, the CuN layer can suppress the formation of the copper silicide layer in the copper interconnection and, therefore, can restrain the increase in electrical resistance.
However, conventional techniques described above have the following problems.
In a method comprising the step of removing a copper oxide film with carboxylic acid, after the cleaning to remove the copper oxide film is carried out, the wafer is taken out from the cleaning equipment and transferred for the step of growing the films. During the transfer, the wafer may be exposed to the air so that the copper surface therein may be reoxidized, leading to a problem of the increase in electrical resistance and the decrease in adhesion between the copper interconnection and the copper-diffusion prevention film formed thereon.
Meanwhile, although a method with a reducing plasma treatment can control the increase in resistance in a certain degree, the method brings about another problem of the decrease in interconnection lifetime. In fact, it is the present inventors who first confirmed, through experiments, that a reducing plasma treatment may lower the interconnection lifetime, due to the electromigration or the like, and give rise to a variation in resistance. To remove the copper oxide film thoroughly by the plasma treatment, it is necessary to employ considerably rigorous conditions for the plasma treatment and, as a result, the copper surface becomes rugged. Furthermore, since the nitridation to form CuN proceeds with copper oxide still partially remaining on the copper surface, the film thickness of the CuN becomes non-uniform and, herewith, the film thickness of a copper silicide layer that is to be formed in the copper interconnection becomes also non-uniform. This presumably causes a lowering of the interconnection lifetime and produces variation in resistance.
Further, in the method using the reducing plasma treatment, there are occasions where the film thickness of the copper-diffusion prevention film becomes non-uniform, owing to the unevenness of the underlying layer surface. This necessitates, in the later step of hole etching to form an interconnection connecting plug, to perform overetching further more so as to remove that copper-diffusion prevention film so that the degradation of the copper interconnection surface may be brought about by the plasma exposure.
SUMMARY OF THE INVENTION
In light of the above problems, an object of the present invention is to provide a manufacturing method of a semiconductor device which can improve the interconnection lifetime and the variation in resistance of the copper interconnection, while controlling the increase in resistance thereof, and, in addition, can raise the manufacturing stability.
The present invention provides a method of manufacturing a semiconductor device; which comprises the steps of:
forming a copper-containing film on a semiconductor substrate;
removing, with a cleaning agent, a copper oxide on a surface of said copper-containing film;
applying a nitriding treatment to the surface of said copper-containing film from which the copper oxide has been removed; and
forming a copper-diffusion prevention film comprising a silicon on said copper-containing film which has been subjected to the nitriding treatment.
Further, the present invention provides a method of manufacturing a semiconductor device; which comprises the steps of:
forming a copper-containing film on a semiconductor substrate;
removing a copper oxide on a surface of said copper-containing film;
applying an anticorrosive treatment to the surface of the copper-containing film, with an anticorrosive-containing solution being used;
carrying out a heating treatment to detach the anticorrosive which is adhered onto the surface of the copper-containing film and, subsequently, applying a nitriding treatment to the surface of said copper-containing film; and
forming a copper-diffusion prevention film comprising a silicon on said copper-containing film which has been subjected to the nitriding treatment.
Further, the present invention provides a method of manufacturing a semiconductor device; which comprises the steps of:
forming a copper-containing film on a semiconductor substrate; applying a nitriding treatment to the surface of said copper-containing film without allowing the semiconductor substrate to be exposed to an oxygen-containing atmosphere; and
forming a copper-diffusion prevention film comprising a silicon on said copper-containing film which has been subjected to the nitriding treatment.
In the afore-mentioned manufacturing methods, a nitriding treatment is applied to the surface of a copper-containing film, after copper oxide which is present on the surface of the copper-containing film is removed with a cleaning agent. Or a nitriding treatment is applied to the surface of a copper-containing film without allowing a semiconductor substrate to be exposed to an oxygen-containing atmosphere. In the method described in the BACKGROUND, wherein a copper oxide film is removed by a plasma treatment with a reducing gas, it is necessary to conduct the plasma treatment under somewhat rigorous conditions. For instance, in
Aoki Hidemitsu
Ohto Koichi
Okada Norio
Tanikuni Takamasa
Tomimori Hiroaki
Fourson George
Garcia Joannie Adelle
NEC Corporation
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