Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1997-08-12
2001-01-30
Whitehead, Jr., Carl (Department: 2822)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S622000, C438S643000, C438S653000, C438S683000
Reexamination Certificate
active
06180513
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus and method for manufacturing a semiconductor device, particularly, to a pretreatment in preparation for a selective CVD (Chemical Vapor Deposition) treatment for burying W (tungsten) in a contact hole to achieve an electrical connection between a silicon wafer and a conductive layer formed above the wafer surface.
In the manufacture of a semiconductor device having a multi-wiring layer structure, a conductive plug material, e.g., W, is buried in general in a contact hole such as a via-hole connecting upper and lower wiring layers so as to improve the reliability of the upper wiring layer made of, for example, aluminum. On the other hand, where W is buried by selective CVD in a contact hole for electrically connecting a first conductive layer, such as a diffusion region formed in a semiconductor substrate, e.g. a Si layer, to a second conductive layer formed above the first conductive layer, it is necessary to form a barrier metal layer on the surface of the first conductive layer (or bottom of the contact hole) in order to prevent the buried W layer from biting the Si layer.
FIGS. 1A
to
1
F are cross sectional views collectively showing schematically the conventional selective CVD method for burying W in a contact hole. On the other hand,
FIG. 2
a flow chart schematically showing the flow of the required treatments. In the first step, a contact hole
3
is formed in an insulating film
2
formed to cover the surface of a silicon wafer
1
, as shown in FIG.
1
A. Then, a titanium (Ti) film
4
and a titanium nitride (TiN) film
5
are formed successively by a sputtering method on the entire surface including the contact hole
3
, as shown in FIG.
1
B. The TiN film
5
acts as a cap material serving to prevent the Ti film
4
from being nitrided or oxidized in the subsequent annealing step. Then, annealing is applied under a nitrogen gas atmosphere at 200° C. or higher so as to achieve silicidation at the interface between the silicon wafer
1
and the Ti film
4
. As a result, a barrier metal layer
6
made of TiSi
x
is formed at the bottom region of the contact hole
3
, as shown in FIG.
1
C.
After formation of the TiSi
x
film
6
, the excess Ti film
4
and TiN film
5
, which were not involved in the above-noted silicidation, are removed. In the subsequent step, a native oxide (SiO
2
) film
7
formed on the surface of the TiSi
x
film
6
as shown in
FIG. 1D
is removed as a pretreatment in preparation for the selective CVD treatment for burying W in the contact hole
3
. Then, a W film
8
is buried in the contact hole
3
by the selective CVD treatment such that the W film
8
is in direct contact with the TiSi
x
film
6
having the native oxide film
7
removed from the surface, as shown in FIG.
1
E. Finally, a second conductive layer
9
acting as an upper wiring layer is formed on the entire surface, as shown in
FIG. 1F
, thereby to achieve a multi-wiring structure in which the silicon wafer (first conductive layer)
1
is electrically connected to the second conductive layer
9
via the W film
8
filling the contact hole
3
.
In the conventional method, however, it is necessary to remove the excess Ti film
4
and the TiN film
5
after formation of the TiSi
x
film
6
, as shown in FIG.
2
. What should also be noted is that the TiSi
x
film
6
soon after formation is exposed to the air atmosphere before the selective CVD treatment for burying W in the contact hole
3
, with the result that the native oxide film
7
is formed on the surface of the TiSi
x
film
6
. Naturally, it is absolutely necessary to remove the native oxide film
7
before deposition of the W film
8
. Further, a sputtering method is employed for forming the Ti film
4
and the TiN film
5
. It should be noted in this connection that, where the contact hole
3
has a high aspect ratio, i.e., a ratio of the height to the diameter, the sputtered particles fail to reach sufficiently the bottom of the contact hole
3
, resulting in failure to form a TiSi
x
film of a high quality.
BRIEF SUMMARY OF THE INVENTION
As described above, a large number of treating steps are required in the conventional method for forming a TiSi
x
film. Also, the conventional method necessitates a pretreatment for removing a native oxide film. Further, it is difficult to form a TiSi
x
film of a high quality where the film is formed within a contact hole having a high aspect ratio.
A first object of the present invention is to provide an apparatus and method for manufacturing a semiconductor device, which permit markedly decreasing the number of treating steps required for forming a barrier metal layer and also permit forming a high quality barrier metal layer efficiently even if the barrier metal layer is formed within a contact hole having a high aspect ratio.
A second object of the present invention is to provide a method and apparatus for manufacturing a semiconductor device, which permit decreasing the number of treating steps and also permit markedly simplifying the construction of the apparatus.
According to a first aspect of the present invention, there is provided an apparatus for manufacturing a semiconductor device, comprising means for forming a barrier metal layer in a bottom portion of a contact hole made through an insulating film formed on a first conductive layer, the barrier metal layer being formed before burying in the contact hole a conductive material layer connected to a second conductive layer and being formed by a plasma CVD method using, as a source gas, a gas containing a substance capable of self-alignment with the first conductive layer.
According to a second aspect of the present invention, there is provided an apparatus for manufacturing a semiconductor device, comprising:
means for forming a barrier metal layer at a bottom portion of a contact hole formed through an insulating film for insulation between a first conductive layer and a second conductive layer, the barrier metal layer being formed before burying a conductive material in the contact hole and being formed by a plasma CVD method using, as a source gas, a gas containing a substance capable of self-alignment with the first conductive layer; and
means for consecutively forming a film of the conductive material by a selective CVD method on the barrier metal layer formed in the bottom portion of the contact hole.
According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the step of forming a barrier metal layer in a bottom portion of a contact hole made through an insulating film formed on a first conductive layer, the barrier metal layer being formed before burying in the contact hole a conductive material layer connected to a second conductive layer and being formed by a plasma CVD method using, as a source gas, a gas containing a substance capable of self-alignment with the first conductive layer.
Further, according to a fourth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of:
forming a barrier metal layer at a bottom portion of a contact hole formed through an insulating film for insulation between a first conductive layer and a second conductive layer, the barrier metal layer being formed before burying in the contact hole a conductive material and being formed by a plasma CVD method using, as a source gas, a gas containing a substance capable of self-alignment with the first conductive layer; and
consecutively forming a film of the conductive material by a selective CVD method on the barrier metal layer formed in the bottom portion of the contact hole.
The apparatus and method of the present invention permit forming a barrier metal layer by self-alignment with a first conductive layer. As a result, formation of the barrier metal layer can be simplified. In addition, the barrier metal layer can be formed in a bottom portion of a contact hole without fail regardless of the aspect ratio of the co
Otsuka Kenichi
Otsuka Mari
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Guerrero Maria
Jr. Carl Whitehead
Kabushiki Kaisha Toshiba
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