Method to form C54 TiSi2 for IC device fabrication

Details Method to form C54 TiSi2 for IC device fabrication Method to form C54 TiSi2 for IC device fabrication

2001-04-20

2004-08-17

Fourson, George (Department: 2823)

Semiconductor device manufacturing: process

Coating with electrically or thermally conductive material

To form ohmic contact to semiconductive material

C438S655000, C438S656000, C438S658000, C438S662000, C438S683000

Reexamination Certificate

active

06777329

ABSTRACT:

BACKGROUND OF THE INVENTION
(1) Field of the Invention
The invention relates to the fabrication of integrated circuit devices, and more particularly, to a method of using laser annealing to form a high quality titanium silicide in the fabrication of integrated circuits.
(2) Description of the Prior Art
Due to the “fine line effect,” C54 titanium disilicide is difficult to achieve in sub 0.18 &mgr;m polysilicon lines. Typically, a C49 phase titanium disilicide (TiSi
2
) is formed after a first annealing. This material has a high resistivity however, so a second annealing is performed to change the phase of the TiSi
2
to C54, which has much lower resistivity. An additional silicon implantation step has been used for salicidation, to change the top portion of the silicon substrate to an amorphous layer, but this causes transient enhanced dopant diffusion, dopant redistribution, silicon defects, and, hence, device degradation. It is desired to find a method to form a high quality C54 TiSi
2
that can be achieved for deep submicron feature sizes.
A number of patents teach formation of C54 titanium silicide. U.S. Pat. No. 5,937,325 to Ishida teaches using laser annealing to form C49 TiSi
2
, then a rapid thermal annealing (RTA) to form C54 TiSi
2
on a polysilicon gate. Then, a first and second RTA form C49, then C54 TiSi
2
on the source/drain regions. U.S. Pat. No. 6,054,387 to Fukuda teaches forming C49 TiSi
2
by RTA, then warping the device while performing a second RTA to form C54 TiSi
2
. U.S. Pat. No. 6,071,552 to Ku discloses deposition of C49 TiSi
2
, then an RTA to form C54 TiSi
2
. U.S. Pat. No. 5,956,137 to Lim et al discloses a method to use Raman analysis to determine the phase of a silicide.
SUMMARY OF THE INVENTION
A principal object of the present invention is to provide an effective and very manufacturable method of fabricating a titanium disilicide film in the fabrication of an integrated circuit.
A further object of the invention is to provide a method of fabricating C54 phase titanium disilicide in the fabrication of an integrated circuit.
Yet another object is to provide a method of forming a C54 phase titanium disilicide film for deep submicron devices.
Yet another object is to provide a method of forming a C54 phase titanium disilicide film for deep submicron devices wherein the C54 phase is formed based on a C40 titanium disilicide.
Yet another object of the invention is to forming a C54 phase titanium disilicide film using laser annealing to first form C40 phase titanium disilicide, and then using a lower temperature annealing to form C54 phase titanium disilicide.
In accordance with the objects of the invention a novel method for forming a C54 phase titanium disilicide film in the fabrication of an integrated circuit is achieved. A semiconductor substrate is provided having silicon regions to be silicided. A titanium layer is deposited overlying the silicon regions to be silicided. The substrate is subjected to a first annealing whereby the titanium is transformed to phase C40 titanium disilicide where it overlies the silicon regions and wherein the titanium not overlying the silicon regions is unreacted. The unreacted titanium layer is removed. The substrate is subjected to a relatively low temperature second annealing whereby the phase C40 titanium disilicide is transformed to phase C54 titanium disilicide to complete formation of a phase C54 titanium disilicide film in the manufacture of an integrated circuit.


REFERENCES:
patent: 5937325 (1999-08-01), Ishida
patent: 5956137 (1999-09-01), Lim et al.
patent: 6054387 (2000-04-01), Fukuda
patent: 6071552 (2000-06-01), Ku
patent: 6514859 (2003-02-01), Erhardt et al.
Mouroux, Aliette; The Reactive Formation of TiSi2 in the Presence of Refractory Metals (from V to W), Royal Institute of Technology, Department of Electronics, Stockholm 1,999.*
Mouroux, Aliette; The Reactive Formation of TiSi2 in the Presence of Refractory Metals (from V to W), Royal Institute of Technology, Department of Electronics, Stockholm 1,999; pages.

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