Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1998-03-02
2001-08-14
Meier, Stephen D. (Department: 2822)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S573000, C438S642000, C438S652000, C438S657000
Reexamination Certificate
active
06274489
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a manufacturing method of a semiconductor apparatus, and more particularly to a method in which a two-layer structured electrode wiring film including a silicide film such as a combination of a polysilicon film and a tungsten silicide (WSix) film is formed.
2. Description of the Prior Art
A conventional semiconductor apparatus is described with reference to FIG.
1
.
As shown in
FIG. 1
, an impurity diffusing region
2
is formed on an upper surface of a semiconductor substrate
1
, two MOS transistors are formed on the semiconductor substrate
1
to be adjacent to the impurity diffusing region
2
, a two-layer structured electrode wiring film
9
A composed of a polysilicon film
8
making contact with the impurity diffusing region
2
and a tungsten silicide (WSix) film
9
is formed between the MOS transistors.
In detail, the impurity diffusing region
2
is formed by implanting n+ impurity into an upper portion of the semiconductor substrate
1
, a gate insulating film
3
is formed on the semiconductor substrate
1
so as to expose the impurity diffusing region
2
, and a first gate electrode
4
A and a second gate electrode
4
B facing each other are formed on the gate insulating film
3
. Also, a first insulating film
5
A is formed on the first gate electrode
4
A, and a second insulating film
5
B is formed on the second gate electrode
4
B. Also, a first side wall spacer film
7
A is formed on a side wall of a combination of the first gate electrode
4
A and the first insulating film
5
A, and a second side wall spacer film
7
B is formed on a side wall of a combination of the second gate electrode
4
B and the second insulating film
5
B on condition that the first and second side walls
7
A and
7
B face each other.
Also, the electrode wiring film
9
A composed of the polysilicon film
8
and the tungsten silicide (WSix) film
9
is formed on the impurity diffusing region
2
. In the polysilicon film
8
, impurity is implanted to make the polysilicon film
8
conductive, so that the polysilicon film
8
is electrically connected with the impurity diffusing region
2
.
In addition, a first wiring film
6
A is formed on the first insulating film
5
A, a second wiring film
6
B is formed on the second insulating film
5
B, and the first and second wiring films
6
A and
6
B and the first and second insulating films
5
A and
5
B are covered with an inter-layer insulating film
10
A made of boron-phoso silicate glass.
Also, after a photo-resist film (not shown) is formed on the inter-layer insulating film
10
A, an opening area is formed in the inter-layer insulating film
10
A by using the photo-resist film as a mask so as to expose the electrode wiring film
9
A composed of the polysilicon film
8
and the tungsten silicide (WSix) film
9
, and the electrode wiring film
9
A and the inter-layer insulating film
10
A are covered with a metal wiring film
10
B made of aluminum or a material including aluminum (for example, Al—Si—Cu) to electrically make the electrode wiring film
9
A contact with the metal wiring film
10
B.
To obtain a structure of the conventional apparatus shown in
FIG. 1
, the polysilicon film
8
is formed to be filled in a concave area between the first side wall spacer film
7
A formed on the side wall of the combination of the first gate electrode
4
A and the first insulating film
5
A and the second side wall spacer film
7
B formed on the side wall of the combination of the second gate electrode
4
B and the second insulating film
5
B, ions are implanted in the polysilicon film
8
to make the polysilicon film
8
conductive, and the tungsten silicide (WSix) film
9
is formed on the polysilicon film
8
. Thereafter, after a photo-resist film is formed on the tungsten silicide film
9
, the tungsten silicide film
9
and the polysilicon film
8
are patterned by etching and removing a portion of the tungsten silicide film
9
and a portion of the polysilicon film
8
while using the photo-resist film as a mask. Therefore, as shown in
FIG. 2
, the electrode wiring film
9
A is formed.
Thereafter, after the inter-layer insulating film
10
A is formed over the entire surface of the electrode wiring film
9
A and the entire surface of the first and second insulating films
5
A and
5
B, an opening area is formed in the inter-layer insulating film
10
A to expose the tungsten silicide film
9
, an aluminum film is formed over the entire surface of the tungsten silicide film
9
and the entire surface of the inter-layer insulating film
10
A and is patterned. Therefore, the metal wiring film
10
B electrically connected with the electrode wiring film
9
A is formed.
However, in cases where the conventional semiconductor apparatus is manufactured according to the above method, there are many drawbacks. That is, it is required to thin the polysilicon film
8
to arrange the electrode wiring film
9
A composed of the polysilicon film
8
and the tungsten silicide (WSix) film
9
in the conventional semiconductor apparatus. Accordingly, because a film thickness of the polysilicon film
8
is made small, as shown in
FIG. 2
, a ravine area CP is formed on the tungsten silicide (WSix) film
9
when the tungsten silicide (WSix) film
9
is formed on the polysilicon film
8
. Therefore, when a photo-resist film planned to be used as a mask in a patterning operation of the electrode wiring film
9
A by which the some is patterned in a photo-lithography process by exposing the photo-resist film to light, the photo-resist film undesirably remains in the ravine area CP, so that there is a first drawback that the electrode wiring film
9
A cannot be reliably patterned. To prevent this drawback, in cases where an intensity of the exposing light is increased, halation occurs in the exposing operation, so that there is another drawback that the photo-resist film is not correctly patterned and the electrode wiring film
9
A cannot be patterned with high accuracy.
Also, because a film thickness of the polysilicon film
8
is made small, a height of the electrode wiring film
9
A is lowered. Therefore, as shown in
FIG. 1
, a height al of a side wall of the inter-layer insulating film
10
A is heightened, an opened area surrounded by the side wall of the inter-layer insulating film
10
A is deepened. In this case, there is a second drawback that a step coverage of the metal wiring film
10
B arranged on the side wall of the inter-layer insulating film
10
A is degraded.
To avoid the first and second drawbacks, as shown in
FIG. 3
, it is postulated that a polysilicon film
8
A placed beneath the tungsten silicide (WSix) film
9
is thickened.
However, in an ion implanting process performed to make the polysilicon film
8
A conductive, though ions are sufficiently implanted in an upper portion of the polysilicon film
8
A, ions are not sufficiently implanted into a bottom portion PB of the polysilicon film
8
A near to the impurity diffusing region
2
. Also, ions are not sufficiently diffused from the bottom portion PB of the polysilicon film
8
A to the substrate
1
. Therefore, the polysilicon film
8
A is not sufficiently made conductive. Accordingly, there is another drawback that a contact resistance of the polysilicon film
8
A becomes higher than a desired value. Also, there is another drawback that contact resistances in various portions of the polysilicon film
8
A cannot be uniformly set because implanting amounts of ion in the various portions of the polysilicon film
8
A differ from each other.
To sufficiently inject ions into the bottom portion PB of the polysilicon film
8
A, it is proposed that an acceleration voltage applied to the ions is heightened.
However, in this case, an amount of ion implanted into the impurity diffusing region
2
placed beneath the polysilicon film
8
A is increased, the ions implanted into the impurity diffusing region
2
are diffused in a lateral direction, so that there is another drawback that a punch through occurs
Matsuda Toshiharu
Ono Masahiro
Sakamura Masaji
Brophy Jamie L.
Hogan & Hartson LLP
Meier Stephen D.
Sanyo Electric Co,. Ltd.
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