Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2001-02-09
2004-05-18
Eckert, George (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S295000, C438S003000
Reexamination Certificate
active
06737697
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device equipped with a capacitor including a capacitor dielectric film made from a dielectric film with a large dielectric constant (hereinafter referred to as a highly dielectric film) or a ferroelectric film, and method and system for fabricating the same.
In accordance with recent trend toward a high operation speed and small power consumption of microcomputers and the like, consumer electronic equipment are highly developed, and semiconductor elements included in semiconductor devices used in the consumer electronic equipment have been rapidly refined.
As a result, unwanted radiation, that is, electromagnetic wave noise caused in electronic equipment, has become a serious problem. As means for reducing the unwanted radiation, attention is paid to a technique to involve, in a semiconductor integrated circuit device, a capacitor having large capacity and including a capacitor dielectric film of a highly dielectric film or a ferroelectric film.
Furthermore, in accordance with development of higher integration of a dynamic RAM, a technique to use a highly dielectric film or a ferroelectric film as a capacitor dielectric film of a capacitor instead of a conventionally used oxide or nitride of silicon is now widely studied.
Moreover, for the purpose of realizing practical use of a nonvolatile RAM capable of operating at a low voltage and reading or writing at a high speed, a ferroelectric film with a spontaneous polarization characteristic is now earnestly studied and developed.
Accordingly, it is significant to develop a method for realizing higher integration of a semiconductor device without degrading characteristics of a capacitor.
Now, a conventional method of fabricating a semiconductor device will be described with reference to
FIGS. 11A through 11C
,
12
A and
12
B.
First, as is shown in
FIG. 11A
, after forming an isolation region
11
and a gate electrode
12
of an FET on a semiconductor substrate
10
, impurity diffusion layers and the like (not shown) of the FET are formed in a surface portion of the semiconductor substrate
10
, and an insulating film
13
is deposited to cover the isolation region
11
and the gate electrode
12
. Thereafter, on a portion of the insulating film
13
above the isolation region
11
, a capacitor lower electrode
14
of a platinum film or the like, a capacitor dielectric film
15
of a highly dielectric film or a ferroelectric film and a capacitor upper electrode
16
of a platinum film or the like are formed. The capacitor lower electrode
14
, the capacitor dielectric film
15
and the capacitor upper electrode
16
together form a capacitor.
Next, as is shown in
FIG. 11B
, after forming a first protection film
17
for covering the capacitor, a contact hole
18
of the FET is formed in the insulating film
13
and a contact hole
19
of the capacitor is formed in the first protection film
17
. Then, a metal film such as a titanium film and an aluminum alloy film is deposited over the insulating film
13
and the first protection film
17
, and the metal film is patterned into a first interconnection layer
20
connected to the impurity diffusion layer of the FET or the capacitor upper electrode
16
. Thereafter, the first interconnection layer
20
is subjected to a heat treatment.
Then, as is shown in
FIG. 11C
, by plasma tetraethylorthosilicate (hereinafter referred to as TEOS) CVD, an interlayer insulating film (plasma TEOS film)
21
of a silicon oxide film is deposited over the first interconnection layer
20
and the capacitor. In consideration of planarization by reflow, the interlayer insulating film
21
is formed so as to have a thickness of approximately 1 &mgr;m or more in a portion above the first interconnection layer
20
on the capacitor upper electrode
16
.
Next, after planarizing the interlayer insulating film
21
, a contact hole is formed in the interlayer insulating film
21
, and a second interconnection layer
22
connected to the first interconnection layer
20
is formed on the interlayer insulating film
21
as is shown in FIG.
12
A.
Then, as is shown in
FIG. 12B
, a second protection film
23
is deposited on the interlayer insulating film
21
so as to cover the second interconnection layer
22
.
However, since the interlayer insulating film
21
is formed from the plasma TEOS film in the conventional structure, the interlayer insulating film
21
applies merely small stress to the capacitor and tends to be compressive. Accordingly, there arises a problem that the capacitor dielectric film
15
cannot sufficiently attain spontaneous planarization, and hence, the capacitor cannot attain good characteristics.
Therefore, the present inventors have proposed, in Japanese Patent Publication No. 2846310, a technique to use, instead of the plasma TEOS film, a silicon oxide film formed by TEOS-O
3
CVD (hereinafter referred to as the TEOS-O
3
film) as the interlayer insulating film
21
.
When the TEOS-O
3
film is used as the interlayer insulating film
21
, stress applied to the capacitor can be increased, so as to improve the characteristics of the capacitor.
The use of the TEOS-O
3
film as the interlayer insulating film, however, causes other problems as follows: Defects such as holes are locally formed in the interlayer insulating film of the TEOS-O
3
film; and the growth rate of the TEOS-O
3
film is varied depending upon the kind of underlying film.
Such problems lead to quality degradation of a semiconductor integrated circuit device, and in addition, the characteristics of the capacitor cannot be improved because stress cannot be uniformly applied to the capacitor.
SUMMARY OF THE INVENTION
In consideration of the aforementioned problems, an object of the invention is improving the characteristics of a TEOS-O
3
film formed on a capacitor.
In order to achieve the object, the first semiconductor device of this invention comprises a capacitor including a capacitor lower electrode, a capacitor dielectric film of a highly dielectric film or a ferroelectric film and a capacitor upper electrode successively formed on a semiconductor substrate; a protection film formed on the semiconductor substrate over the capacitor; a first TEOS-O
3
film having a relatively large water content formed on the protection film through first TEOS-O
3
CVD where an ozone concentration is relatively low; and a second TEOS-O
3
CVD film having a relatively small water content formed on the first TEOS-O
3
film through second TEOS-O
3
CVD where the ozone concentration is relatively high.
In the first semiconductor device, the first TEOS-O
3
film formed on the protection film covering the capacitor is formed through the first TEOS-O
3
CVD where the ozone concentration is relatively low. Therefore, the first TEOS-O
3
film can attain good film quality with no defects such as holes and can be improved in its adhesion to the protection film due to its large water content. Also, since the second TEOS-O
3
film is formed through the second TEOS-O
3
CVD where the ozone concentration is relatively high, it can apply large stress to the capacitor dielectric film of the capacitor due to its small water content. Accordingly, the spontaneous polarization characteristic of the capacitor dielectric film can be improved, resulting in improving the characteristics of the capacitor. As a result, a semiconductor device including a highly reliable capacitor can be realized.
The first semiconductor device preferably further comprises a hydrophobic primer layer formed on a surface of the protection film.
Thus, the first TEOS-O
3
film is formed on the protection film having a hydrophobic surface and hence can be satisfactorily grown to attain good step coverage. Accordingly, the step coverage of an interlayer insulating film formed on the capacitor can be improved, so as to improve the insulating property and the surface planeness of the interlayer insulating film.
The first semiconductor device preferably further comprises an underlying oxide film formed, betwe
Hayashi Shinichiro
Judai Yuji
Kutsunai Toshie
Nagano Yoshihisa
Eckert George
Matsushita Electric - Industrial Co., Ltd.
Nguyen Joseph
Nixon & Peabody LLP
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