Semiconductor device manufacturing: process – Coating of substrate containing semiconductor region or of... – Multiple layers
Reexamination Certificate
1999-08-12
2001-05-08
Whitehead, Jr., Carl (Department: 2822)
Semiconductor device manufacturing: process
Coating of substrate containing semiconductor region or of...
Multiple layers
C438S758000
Reexamination Certificate
active
06228778
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a semiconductor device and a process for manufacturing the same. More particularly, the present invention relates to a semiconductor device having an improved interlayer insulating film and a process for manufacturing the same.
2. Background Art
The recent finer patterning of semiconductor devices has posed a serious problem with lead line delay due to the capacitance of the interlayer insulating film. Reducing the capacitance of the interlayer insulating film is an important future subject. This is true particularly in the case of lead lines finer than 0.3 m. Thus, there is a demand for a new interlayer insulating film which has a low dielectric constant and good burying properties and surface leveling properties.
It is expected that this demand will be satisfied by fluorine-containing silicon oxide film (referred to as SiOF film hereinafter). See “High density plasma CVD fluoro-silicate glass gap-filling for sub-half micron CMOS devices” (Proceedings of VMIC Conference 1997).
The SiOF film has a decreased dielectric constant on account of the introduction of Si-F bonds into a silicon oxide film. For example, a silicon oxide film (free of Si-F bonds) decreases in dielectric constant from 4.4 to 3.5 when it contains about 10% fluorine.
The decrease in dielectric constant is probably due to the presence of Si-F bonds in the film in such a way that the Si-O network is partly broken and minute voids (or defects) are formed in the film. Such minute voids are three-membered rings as shown in FIG.
7
(
a
) or four-membered rings as shown in FIG.
7
(
b
). And such minute voids lead to a decrease in film density.
These minute voids (defects) present a new problem of deteriorating the resistance of the film to moisture absorption. In other words, introducing fluorine atoms into the film to lower its dielectric constant increases the minute defects due to three- or four-membered rings, thereby permitting the easy infiltration of moisture into the film from the atmosphere. The result is that the film changes into one which contains a large amount of moisture. Such a moisture-rich film has a dielectric constant as high as about 4.0. In addition, it causes imperfect contact at via holes due to gas (mainly water vapor) escaping from it in the subsequent process as shown in FIG.
8
. (This is referred to as poisoned via failure).
FIG. 8
shows a structure which is composed of a silicon substrate
101
, an aluminum interconnection
102
, a fluorine-containing silicon oxide film
103
(of conventional type), a titanium nitride film
105
, and a tungsten film
106
. It is to be noted that voids are formed in the fluorine-containing silicon oxide film
103
and moisture
107
migrates from them to cause contact failure.
SUMMARY OF THE INVENTION
The present invention was proposed to address the above-mentioned problems involved in the prior art technology. Therefore, it is an object of the present invention to provide a silicon oxide insulting film which is incorporated with fluorine atoms to lower its dielectric constant without adverse effect on its resistance to moisture absorption. It is another object of the present invention to provide a process for manufacturing such an insulating film.
According to one aspect of the present invention, a semiconductor device has an interlayer insulating film which is comprised of molecules with silicon-oxygen bonds and silicon-fluorine bonds and contains a rare gas in concentration higher than 10
11
atoms per cm
2
. In other words, the interlayer insulating film contains a rare gas in concentration higher than 10
18
atoms per cm
3
.
In another aspect of the present invention, the semiconductor device has an interlayer insulating film comprised of a fluorine-containing silicon oxide film which contains a rare gas in concentration higher than 10
11
atoms per cm
2
. In other words, the fluorine-containing silicon oxide film contains a rare gas in concentration higher than 10
18
atoms per cm
3
.
In another aspect of the present invention, the rare gas included in the insulation film is at least one type of gas selected from neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).
According to another aspect of the present invention, in a process for manufacturing a semiconductor device, an interlayer insulating film is formed which is comprised of molecules with silicon-oxygen bonds and silicon-fluorine bonds by a chemical vapor deposition method from a material gas including a silicon-containing gas, a fluorine compound gas, a rare gas, and oxygen such that the interlayer insulating film contains the rare gas in concentration higher than 10
11
atoms per cm
2
. In other words, the interlayer insulating film contains a rare gas in concentration higher than 10
18
atoms per cm
3
.
In another aspect of the present invention, in the process for manufacturing a semiconductor device, the interlayer insulating film is formed by a fluorine-containing silicon oxide film to contain a rare gas in concentration higher than 10
11
atoms per cm
2
. In other words, the interlayer insulating film is formed to contain a rare gas in concentration higher than 10
18
atoms per cm
3
.
In another aspect of the present invention, in the process for manufacturing a semiconductor device, the silicon-containing gas is SiH
4
gas and the fluorine compound gas is SiF
4
gas, and the total flow rate of the rare gas and oxygen is greater than three times the total flow rate of the SiH
4
gas and SiF
4
gas.
In another aspect of the present invention, in the process for manufacturing a semiconductor device, the silicon-containing gas is SiH
4
gas and the fluorine compound gas is SiF
4
gas, and the flow rate of the rare gas is greater than three times the total flow rate of the SiH
4
gas and the SiF
4
gas.
In another aspect of the present invention, in the process for manufacturing a semiconductor device, the rare gas is at least one type of gas selected from neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).
Other and further objects, features and advantages of the invention will appear more fully from the following description.
REFERENCES:
patent: 5521424 (1996-05-01), Ueno et al.
patent: 5698901 (1997-12-01), Endo
patent: 5703404 (1997-12-01), Matsuura
patent: 5935649 (1999-08-01), Koizumi et al.
patent: 5976973 (1999-11-01), Ohira et al.
patent: 7-254592 (1995-10-01), None
patent: 8-213386 (1996-08-01), None
patent: 8-330293 (1996-12-01), None
patent: 9-69518 (1997-03-01), None
N. Hayasaka et al., “Fluorine Doped SiO2for Low Dielectric Constant Films in Sub-Half Micron ULSI Multilevel Interconnection”, Extended Abstracts of the 1995 International Conference on Solid State Devices and Materials, 1995, pp. 157-159.
M. Hayashi et al., “High Density Plasma CVD Fluoro-Silicate Glass Gap-Filling for Sub-Half Micron CMOS Devices”, DUMIC Conference, Feb. 1997, pp. 205-212.
T. Fukuda et al., “Highly Reliable SiOF Film Formation Using High Density Plasma Containing Hydrogen”, DUMIC Conference, 1997, pp. 41-48.
Jr. Carl Whitehead
McDermott & Will & Emery
Mitsubishi Denki & Kabushiki Kaisha
Vockrodt Jeff
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