Abstract
The interfacial reactions and chemical phase formation between nickel and ultrahigh vacuum chemical vapor deposited
Si
0.75
Ge
0.25
alloy have been studied within the temperature range of
300–900 °
C
for forming low resistive and uniform silicide films for future application in SiGe based metal–oxide–semiconductor field effect transistor devices. The silicided films were characterized by the x-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, transmission electron microscopy, and micro-Raman microscopy techniques. Smooth and uniform nickel monogermanosilicide
NiSi
0.75
Ge
0.25
films have been observed for samples annealed at around
400–500 °
C
.
For annealing temperatures of
500 °
C
and above, Ge-rich
Si
1−z
Ge
z
grains where
z>0.25
were found among Ge deficient
Ni
y
(
Si
w
Ge
1−w
)
1−y
grains where
w<0.25
and the
Ni
y
(
Si
1−w
Ge
w
)
1−y
phase is thermally stable up to an annealing temperature of
800 °
C
.
We found that the Ni/SiGe reaction is mainly diffusion controlled with Ge and Ni as the dominant diffusing species compared to Si during the annealing process. In addition, Ge has been found to promote agglomeration especially above
700 °
C
,
leading to an abrupt increase in the sheet resistance.