Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – Insulative material deposited upon semiconductive substrate
Reexamination Certificate
1998-06-11
2001-05-01
Whitehead, Jr., Carl (Department: 2822)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
Insulative material deposited upon semiconductive substrate
C438S436000, C438S760000, C438S761000, C438S787000
Reexamination Certificate
active
06225236
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for reforming an undercoating surface prepared for the formation of a film by the CVD (chemical vapor deposition) technique using a reaction gas containing an ozone-containing gas having ozone (O
3
) contained in oxygen (O
2
) and tetraethylorthosilicate (TEOS) (hereinafter referred to as “O
3
/TEOS reaction gas”) and a method for the production of a semiconductor device.
2. Description of the Prior Art
The film formed by the CVD technique using the O
3
/TEOS reaction gas (hereinafter referred to as “O
3
/TEOS CVD SiO
2
film”) has the nature of exhibiting high density, a low etching rate, no shrinkage by a heat treatment even at high temperatures, a small water content, and fine flow quality which increases prominently in accordance with increase of as the O
3
concentration in O
2
. The silicon oxide film formed by using an O
3
/TEOS reaction gas containing O
3
in a high concentration (hereinafter referred to as “high O
3
/TEOS reaction gas”) will be referred to as “high O
3
/TEOS CVD SiO
2
film” and the silicon oxide film formed by using an O
3
/TEOS reaction gas containing O
3
in a low concentration (hereinafter referred to as “low O
3
/TEOS reaction gas”) will be referred to as “low O
3
/TEOS CVD SiO
2
film” hereinafter.
The high O
3
/TEOS CVD SiO
2
film relies for its quality in a great measure on the condition of the surface of an undercoating layer. Particularly when a high O
3
/TEOS CVD SiO
2
film is formed on the surface of a SiO
2
film or a Si
3
N
4
film, for example, the film undergoes abnormal growth and acquires a porous texture and a coarse surface as illustrated in FIG.
1
and suffers a decline in the growth rate of a film.
In contrast, when a low O
3
/TEOS CVD SiO
2
film is formed on the surface of an undercoating layer, such abnormal growth as is observed in the high O
3
/TEOS CVD SiO
2
film does not occur in this low O
3
/TEOS CVD SiO
2
film. The low O
3
/TEOS CVD SiO
2
film, however, is inferior in such film qualities as density to the high O
3
/TEOS CVD SiO
2
film.
For the purpose of forming a film of fine flow shape and high quality and conferring on the film an ability to be buried satisfactorily in a narrow depressed area, therefore, it is necessary to form the high O
3
/TEOS CVD SiO
2
film in such a manner that it is not affected by the condition of the surface of an undercoating layer.
Heretofore, the following methods have been adopted for the purpose of depriving a high O
3
/TEOS CVD SiO
2
film prior to its formation of the dependency thereof on the surface of an undercoating film.
(1) A first method consists in exposing the surface of an undercoating layer
120
to plasma as illustrated in FIG.
2
A. On the undercoating layer
120
which has been reformed consequently, a high O
3
/TEOS CVD SiO
2
film
121
is formed as illustrated in FIG.
2
B.
(2) A second method consists in forming on an undercoating layer
130
a plasma SiO
2
film
131
as an undercoating insulating film by the plasma CVD technique as illustrated in FIG.
3
A. Thus, a high O
3
/TEOS CVD SiO
2
film
132
is formed on the undercoating insulating film
131
as illustrated in FIG.
3
B.
The plasma SiO
2
film
131
may acquire satisfactory adaptability for the high O
3
/TEOS CVD SiO
2
film
132
in terms of the formation of a film, depending on the condition of the film formation adopted by the plasma CVD technique during the formation of the plasma SiO
2
film
131
. When the plasma SiO
2
film
131
of fine adaptability is formed as an undercoating insulating film on the surface of the undercoating layer
130
and then the high O
3
/TEOS CVD SiO
2
film
132
is formed on the plasma SiO
2
film
131
, therefore, the high O
3
/TEOS CVD SiO
2
film
132
consequently obtained acquires fine film qualities.
(3) A third method consists in forming on the surface of an undercoating layer
140
a low O
3
/TEOS CVD SiO
2
film
141
as an undercoating insulating film or forming an O
3
/TEOS CVD SiO
2
film under a low pressure (hereinafter referred to as “low pressure O
3
/TEOS CVD SiO
2
film”)
141
as illustrated in
FIG. 4A. A
high O
3
/TEOS CVD SiO
2
film
142
is formed as illustrated in
FIG. 4B
on the undercoating insulating film
141
. The high O
3
/TEOS CVD SiO
2
film
142
is easily formed because it manifests fine adaptability to the low O
3
/TEOS CVD SiO
2
film or the low pressure O
3
/TEOS CVD SiO
2
film
141
.
The conventional methods mentioned above, however, :
52
severally encounter the following problems.
(1) With the method which resorts to the exposure of the surface of the undercoating layer
120
to plasma, the success thereof in eliminating the dependency on the surface of the undercoating layer
120
is at the mercy of varieties of the surface of the undercoating layer
120
and the condition of the emission of plasma. The condition of the plasma emission, therefore, cannot be common and standardized inclusively for all kinds of undercoating layer
120
but must be optimized with respect to the status i of an individual undercoating layer
120
.
(2) In the case of the method which forms the plasma SiO
2
layer
131
as an undercoating insulating film, the plasma SiO
2
film
131
has too poor a inferior step coverage to suit application to such an undercoating layer as is furnished with fine and deep grooves.
(3) In the case of the method which forms the low O
3
/TEOS CVD SiO
2
film
141
or the low pressure O
3
/TEOS CVD SiO
2
film
141
as an undercoating insulating film in preparation for the formation of the high O
3
/TEOS CVD SiO
2
film
142
, the low O
3
/TEOS CVD SiO
2
film
141
possesses an isotropic film-forming property and requires a thickness of not less than 100 nm for the purpose of averting the influence of the dependency on the surface of the undercoating layer. This film, therefore, is unfit for application to an undercoating layer which is furnished with fine and deep grooves, for example. The low O
3
/TEOS CVD SiO
2
film
141
is unfit for an undercoating insulating film because it has low density as compared with the high O
3
/TEOS CVD SiO
2
film.
SUMMARY OF THE INVENTION
This invention aims to provide a method for reforming an undercoating surface which can be applied even to an undercoating layer possessed of a fine and deep groove (such as, for example, a trench, gap between metal wiring layers, or gap between metal lower layers) while averting the dependency on the surface of an undercoating layer regardless of the condition of the surface of an undercoating layer, and a method for the production of a semiconductor device.
According to the method of this invention for reforming an undercoating surface, an undercoating insulating film is formed on a substrate and the surface of the undercoating insulating layer is further exposed to plasma prior to the formation of a film.
Since the undercoating insulating film is formed on the substrate prior to the formation of a film, the influence of the dependency on the surface of the substrate can be avoided without reference to the condition of the surface of the substrate.
Further, since the surface of the undercoating insulating film is exposed to plasma, the surface of the undercoating insulating film can be reformed. Since this reform is required solely for the surface of the undercoating insulating film formed on the surface of the substrate and not for the inherent surface of the substrate which has a surface condition which varies from kind to kind, the method to be used for the reform of surface can be inclusively common and standardized.
Since the surface of the undercoating insulating film has been reformed when an insulating film, for example, is ready to be formed on the undercoating insulating film, the insulating film can be formed on the undercoating insulating film without being affected by the dependency on the surface of the undercoating film.
It has been confirmed by an experiment conducted by the present inventor that the minimum thickness of the undercoating i
Nishimoto Yuhko
Suzuki Setsu
Canon Sales Co., Inc.
Davis Jamie L.
Jr. Carl Whitehead
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