Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1998-01-22
2001-05-01
Quach, T. N. (Department: 2814)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S643000, C438S648000, C438S680000
Reexamination Certificate
active
06225213
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a manufacturing method for a contact hole and, more particularly, to a manufacturing method for a contact hole, which method includes a step for forming a Ti film by employing chemical vapor deposition.
2. Description of the Related Art
Great efforts are being continued for achieving smaller semiconductor devices with higher density. Currently, VLSI semiconductor devices such as memory devices or logic devices designed with a dimensional standard of about 0.15 &mgr;m are being developed and their prototypes are being made. With such increasing scale of integration of semiconductor devices, the diameters of contact holes are accordingly being made even smaller; however, it is difficult to reduce the depths of contact holes because of the need for wiring resistance or capacity. For this reason, the aspect ratios of contact holes are rapidly increasing in recent years, and there has been high demand for forming metal electrodes featuring good coverage.
Referring now to
FIG. 1
, a conventional method for forming a metal film by the chemical vapor deposition will be described. FIG.
1
A through
FIG. 1C
are cross-sectional views illustrative of the steps wherein the ECR plasma chemical vapor deposition is applied to form a barrier metal film on a contact hole.
First, a contact hole
3
is opened on a 1000 nm-thick insulating film
2
on a silicon substrate
1
as illustrated in FIG.
1
A. Then, as illustrated in
FIG. 1B
, a Ti film
5
is formed to a thickness of a few nanometers on the substrate by using an ECR plasma apparatus under a condition wherein the TiCl
4
flow is 24 sccm, the H
2
flow is 30 sccm, the pressure is 0.12 Pa, the microwave power is 2.8 kW, and the film forming temperature is 420 degrees Celsius. In the next step, as shown in
FIG. 1C
, a TiN film
7
is formed on the substrate in succession by using the same apparatus under a condition wherein the TiCl4 flow is 20 scam, the H
2
flow is 26 sccm, the N
2
flow is 6 sccm, the pressure is 0.23 Pa, the microwave power is 2.8 kW, and the film forming temperature is 420 degrees Celsius. In the conventional example, the flow ratio of TiCl
4
to H
2
is controlled to 0.4 or more so as to suppress the spiculate growth of the Ti film, thereby enhancing the flatness of the film surface to improve the step coating property thereof.
In the conventional manufacturing method for a semiconductor device described above, however, the Ti depositing speed depends on the dose of each reactive species rather than the base substrate; therefore, the step coating property of the Ti film heavily depends on the geometrical shape of the substrate. For this reason, a sufficient thickness of the Ti film cannot be obtained at the bottom of the contact hole having a high aspect ratio, so that stable electrical characteristics of a contact electrode cannot be obtained.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a manufacturing method of a contact hole, which method permits improved Ti coverage on the bottom portion of a contact hole and enables stable formation of a contact electrode even for a contact hole with a high aspect ratio.
To this end, according to the present invention, there is provided a manufacturing method for a semiconductor device, which method includes the steps of: forming an insulating film on a silicon substrate; removing a predetermined portion of the insulating film to form a contact hole where the silicon substrate is exposed; and depositing a titanium film on the exposed silicon substrate and the insulating film by plasma chemical vapor deposition by employing a halogenated titanium, H
2
, a gas containing halogen and a carrier gas, with the substrate temperature set at 550 degrees Celsius or more.
REFERENCES:
patent: 5173327 (1992-12-01), Sandhu et al.
patent: 5175017 (1992-12-01), Kobayashi et al.
patent: 5508066 (1996-04-01), Akahori
patent: 5567243 (1996-10-01), Foster et al.
patent: 5595784 (1997-01-01), Kaim et al.
patent: 5780356 (1998-07-01), Kim
patent: 5-259110 (1993-10-01), None
patent: 7-41948 (1995-02-01), None
patent: 8-283944 (1996-10-01), None
patent: 10-12725 (1998-01-01), None
NEC Corporation
Quach T. N.
Young & Thompson
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