Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1999-08-10
2001-12-11
Bowers, Charles (Department: 2813)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S396000, C438S675000, C438S689000
Reexamination Certificate
active
06329285
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application No. P10-225794 filed Aug. 10, 1998, which application is incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to a plug fabricating method especially suitable for application to fabrication of a connection hole plug and a contact plug made of tungsten.
2. Description of the Related Art
Recently, along with progressive micro-sizing of semiconductor devices, wirings are getting more and more multi-layered when manufacturing semiconductor devices. As a result, steps in manufacturing, processes of connection hole plugs and contact plugs (hereinafter generically called contact plugs) are increasing, and manufacturing processes of semiconiductor devices are getting more and more complex.
A process for fabricating a contact plug is concretely explained below.
As shown in
FIG. 1
, after an inter-layer insulating film
102
of SiO
2
is formed on a Si substrate
101
, a resist pattern (not shown) with a predetermined configuration is made on the inter-layer insulating film
102
. After that, using the resist pattern as a mask, the inter-layer insulating film
102
is etched by reactive ion etching (RIE) to form a contact hole
103
. The resist pattern is removed thereafter. Then, a titanium (Ti) film and a titanium nitride (TiN) film are sequentially formed on the inter-layer insulating film
102
, also covering the side wall and the bottom surface of the contact hole
103
, to make a direct contact layer
104
of Ti/TiN. After that, within a deposition chamber (not shown), a W film
105
is formed on the entire surface of the inter-layer insulating film
102
by blanket tungsten chemical vapor deposition (blanket W—CVD) so as to bury the inside of the contact hole
103
.
Next as shown in
FIG. 2
, the Si substrate
101
is moved into an etching chamber (not shown), and the W film
105
is partly removed by etch-back by RIE using sulfur hexafluoride (SF6) gas as the plasma etching gas.
Next as shown in
FIG. 3
, the direct contact layer
104
is partly removed by etch-back to expose the top surface of the inter-layer insulating film
102
by RIE using Cl2 as the plasma etching gas. As a result, a contact plug
106
of W deposited on the Ti/Tn contact film as the base is formed inside the contact hole
103
.
This conventional process for fabricating a contact plug, however, involved the following problems. That is, as reviewed above, when the contact plug
106
is formed, the direct contact layer
104
such as Ti/TiN film must be made before the W film
105
is formed by blanket W—CVD). Additionally, not limited to the Ti/TiN film mentioned above, various kinds of structures may be used as the direct contact layer
104
, depending upon the process actually employed. Therefore, etch-back processing had to be done for a plurality of layers including, W film and direct contact layer while coping with any one of such various kinds of structures of the direct contact layer.
Moreover, according to the Inventor's own knowledge, when the direct contact layer
104
is etched, chemical reaction products
107
like titanium fluoride (TiF
x
) as shown in
FIG. 2
are produced and undesirably remain because of influences of residual fluorine (F) in the etching chamber. These reaction products
107
such as TiF
x
invite generation of etching scum
108
on the inter-layer insulating film
102
as shown in
FIG. 3
, and the etching scum
108
invite a decrease in reliability of the wiring formed on an upper layer.
Furthermore, when the contact plug
106
is formed, different chambers were used for the step of depositing the W film
105
, that is, the step of burying W inside the contact hole
103
, and for the step of etch-back of the W film
105
. Therefore, the process for fabricating the contact plug was inevitably complicated.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a plug fabricating method capable of fabricating a minute plug with a good configuration reducing the scum produced during fabrication of the plug, and improving the reliability of a wiring formed on an upper layer.
According to the invention, there is provided a plug fabricating method comprising the steps of:
forming an opening in an insulating film on a substrate;
forming a conducting film to bury the opening; and
partly removing the conducting film by etch-back processing to maintain the conducting film inside the opening, the etch-back processing being conducted by using an etching gas containing at least a chlorine trifluoride gas.
In the present invention, etch-back processing of the conducting film is typically executed in a deposition chamber for forming the conducting film in order to simplify the plug fabricating process. Additionally, in the present invention, the etch-back processing of the conducting film formed in the deposition chamber is preferably executed consecutively in the same deposition chamber.
In the present invention, a wiring is typically formed in connection with the conducting film inside the opening after the etch-back processing of the conducting film in order to make a multi-layered wiring.
In the present invention, the conducting film is preferably made by chemical vapor deposition (CVD). Concretely, when the conducting film is made of tungsten, blanket tungsten chemical vapor deposition is used.
According to the plug fabricating method having the above-summarized construction according to the invention, by using an etching gas containing at least chlorine trifluoride for the etch-back processing of the conducting film, the etching scum can be reduced.
The above, and other, objects, features and advantage of the present invention will become readily apparent from the following detailed description thereof which is to be read in connection with the accompanying drawings.
REFERENCES:
patent: 5078833 (1992-01-01), Kadomura
patent: 5441594 (1995-08-01), Zenke
Bowers Charles
Huynh Yennhu B.
Sonnenschein Nath & Rosenthal
Sony Corporation
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