Cleaning and liquid contact with solids – Processes – Using sequentially applied treating agents
Reexamination Certificate
2000-04-06
2003-03-11
Markoff, Alexander (Department: 1746)
Cleaning and liquid contact with solids
Processes
Using sequentially applied treating agents
C134S001300, C134S002000, C134S019000, C134S026000
Reexamination Certificate
active
06530997
ABSTRACT:
TECHNICAL FIELD
This invention is related to a semiconductor article and a method for processing of semiconductor devices. In particular, the invention is directed to an improved method for cleaning unwanted sputter deposits from source/drain surfaces. Further, the invention is particularly directed to performing an in situ cleaning process to remove re-sputtered SiO
x
deposited on the source/drain surface in a semiconductor device.
BACKGROUND OF THE INVENTION
During manufacture of a semiconductor device, it is necessary to clean selected surfaces of the device before sputter deposition of a metal, such as cobalt which is intended to form a cobalt silicide as part of the final device structure. During such a prior art process, as shown in
FIG. 1
, the argon ions
10
tend to sputter SiO
x
species
12
from the SiO
2
spacer material
14
which deposits on other surfaces, such as source/drain surfaces
16
. As a result, the contaminating SiO
x
species
12
on the source/drain surfaces
16
prevent deposition of cobalt onto silicon to form the desired cobalt silicide layer. The resulting CoSi layer is therefore spotty and potentially discontinuous which can result in degraded performance of a semiconductor device
18
. It is therefore important to develop a process to prevent re-sputtered SiO
2
from depositing on the source/drain surfaces
16
.
SUMMARY OF THE INVENTION
According to one form of the invention, a semiconductor device is prepared for deposition of a cobalt silicide onto a source/drain region. The device undergoes a first standard sputter pre-clean using an inert gas ion, such as argon. After this sputter pre-clean step, the device surfaces are further cleaned by use of a mixture of silicon hydride, or silanes, and hydrogen (H
2
). In the most preferred form, H
2
is used with SiH
4
to assure no deposition of Si. These silicon hydrides can be activated by RF plasma or by an elevated wafer temperature to form SiH
2
and SiH
3
species. These silane derivatives are applied in situ to the semiconductor device, particularly to source/drain surfaces which are to be cleaned in preparation for formation of a cobalt silicide layer. The silane derivatives act to convert to elemental Si the contaminating SiO
x
deposits formed from the argon pre-sputter of the SiO
2
spacer material present in the semiconductor device.
These and other objects, features and advantages of the invention will be apparent from the following description of the preferred embodiments and examples, taken in conjunction with the accompanying drawings described below.
REFERENCES:
patent: 5089441 (1992-02-01), Moslehi
patent: 5403434 (1995-04-01), Moslehi
patent: 6033996 (2000-03-01), Rath et al.
Avanzino Steven C.
Wang Larry Yu
Advanced Micro Devices , Inc.
Foley & Lardner
Markoff Alexander
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