Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
1999-06-25
2001-11-13
Nelms, David (Department: 2818)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S685000
Reexamination Certificate
active
06316355
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for fabricating semiconductor device and, more particularly, to a method for forming a titanium film having excellent step coverage using a sputtering process.
DESCRIPTION OF THE PRIOR ART
The more integrated semiconductor devices are integrated, the smaller the size of metal contact holes is and the more difficult a metal wiring process of a semiconductor device is.
In the metal wiring process, titanium/titanium-nitride (Ti/TiN) films deposited by using a physical vapor deposition (PVD) method have been used as a diffusion barrier, which serves as a barrier for inhibiting a diffusion of silicon atoms from a substrate. However, when an aspect ratio of contact holes is beyond two, it is difficult that the titanium/titanium-nitride films have good step coverage in a lower portion and a sidewall of contact hole. In order to improve such a poor step coverage of the contact hole, many physical vapor depositions (PVD) using a collimator and a ionized methods have been developed. However, such methods are not sufficient enough to obtain the excellent step coverage of the contact hole. There are many developments with respect to the titanium nitride films, but not the titanium films. Actually, the titanium nitride film as a barrier does not affect the device, but the titanium film in contact with a substrate affects greatly the device since it reacts on the silicon layer on the substrate in the following process.
One of approaches to solve such problems is to form high-density plasma in the sputtering chamber by applying RF power. And then a bias is applied to the wafer so that the sputtered titanium atoms may be incident in the direction perpendicular to the wafer and the step coverage of the lower portion of contact hole may be improved.
While the step coverage of contact hole may be improved, however, the high-density plasma and the applied bias may result in the degradation of device with a damage of substrate.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a method for forming a metal wire using a titanium film in a semiconductor device having excellent step coverage without damage of substrate by a sputtering method and a stabilization of metal wiring process.
In accordance with an aspect of the present invention, there is provided a method for forming a metal wire using a titanium film in semiconductor device having a contact hole, the method comprising the steps of: a) depositing a first titanium film on a substrate, in which a contact hole is formed, on conditions of plasma density of less than 10
10
/cm
3
; b) applying a bias to the substrate; and c) depositing a second titanium film on the first titanium film on conditions of plasma density of more than 10
11
/cm
3
.
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Dang Phuc T.
Hyundai Electronics Industries Co,. Ltd.
Jacobson & Holman PLLC
Nelms David
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