Coating processes – Direct application of electrical – magnetic – wave – or... – Chemical vapor deposition
Reexamination Certificate
2002-02-11
2004-06-01
Versteeg, Steven (Department: 1753)
Coating processes
Direct application of electrical, magnetic, wave, or...
Chemical vapor deposition
C204S192200, C204S192300, C216S037000, C216S055000, C427S299000, C427S383100
Reexamination Certificate
active
06743485
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a surface treatment technology. More particularly, the present invention relates to surface treatment for a salicide process.
2. Description of Related Art
An integrated circuit (IC) is produced by a very complicated process. Generally, the complicated process consists of several hundred processing steps, and last about one or two months. During IC production, engineers use many modern technologies and inventions. Because these modern technologies and inventions are advanced but expensive, the IC industry is a highly risky industry that needs enormous investment for support. For this reason, any simplification or combination for those processing steps contributes much to the cost and time reduction for the process as a whole.
Conventionally, the formation of titanium silicide is performed by depositing titanium onto a silicon substrate, followed by rapid thermal annealing (RTA). This titanium layer can be deposited by TiCl
4
-based CVD and silicidation is accomplished in situ during glue layer deposition. The process temperature for TiCl
4
-based Ti is as high as about 650° C. while that of a conventional PVD Ti is only about 200° C. Moreover, the PVD has a deposition rate which is typically several times higher than that of CVD. Therefore, the fast PVD facilitates cost reduction, while the slow TiCl
4
-based CVD has high thermal budget that leads to difficulty in controlling junction leakage.
FIG. 1
is a flow chart schematically illustrating a conventional salicide process and the pre-processing steps thereof. The figure shows nine processing steps comprising the above-mentioned PVD and amorphization. First, on a silicon substrate having a polysilicon gate thereon, step
110
is performed to form an oxide spacer on the sidewall of the polysilicon gate. Steps
125
and
102
a
. belong to an amorphization process
120
, are performed to amorphize the polysilicon gate and the substrate surface. The amorphizing steps
125
,
102
a
, performed in an ion implanter, have a purpose of accelerating the subsequent metal deposition on the substrate. After the amorphizing steps
125
,
102
a
are performed, the surfaces of the substrate, the polysilicon gate and the oxide spacer are wet cleaned as shown in step
130
.
After this wet cleanings
130
, the substrate and the devices thereon are then conveyed from the ion implanter to a sputtering equipment. Step
145
and step
150
a
. belong to a sputtering process
140
, are performed in this sputtering equipment. In step
145
, the surfaces of the substrate, the polysilicon gate and the oxide spacer are dry cleaned by sputtered argon. In step
150
a
, the substrate is covered with a sputtered metal film. The processing steps
120
,
130
,
145
, performed before the metal covering step
150
a
, serve as pre-treatment for a salicide process.
Then, in a first annealing step
150
b
, the metal film thermally reacts with the exposed substrate and polysilicon gate to form silicide films. Step
150
c
then selectively etches the unreacted metal from regions such as the oxide spacer. After the first annealing step
150
b
, the silicide films are typically in a high-resistance phase. For this reason, after the etch step
150
c
. a second annealing step
150
d
is then performed to transform the silicide films into the desired low-resistance phase.
The conventional salicide process and pre-treatment thereof total nine processing steps in all. In the processing steps, the amorphization steps and the sputtering steps should be separately performed in different equipment units, thereby increasing the process complexity. Furthermore, the pre-treatment for the salicide process comprises five processing steps, is also complex and therefore increases the process costs and time. To save process costs and time, there is a need for a method that can simplify or combine those processing steps.
SUMMARY OF THE INVENTION
The present invention is directed to a method for treating a silicon substrate. The silicon substrate is placed into a sputtering equipment. A sputtering step is performed to simultaneously dry clean and amorphize the silicon substrate surface by the sputtering equipment. A titanium film is deposited on the silicon substrate by the sputtering equipment.
In one embodiment of this invention, the titanium film is deposited at about 540° C. by an ionized metal plasma (IMP) equipment.
In this present invention, the sputtering and the deposition steps are performed in the same chamber, thereby improving the wafer throughput.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 5178739 (1993-01-01), Barnes et al.
patent: 5360765 (1994-11-01), Kondo et al.
patent: 6254739 (2001-07-01), Fan
J.C. Patents
Taiwan Semiconductor Manufacturing Co. Ltd.
Versteeg Steven
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