Abstract
Sputtering of niobium and cobalt disilicide films on oxidized Si substrates interposed with an amorphous Si layer has been studied by backscattering spectrometry (BS). Thin NbSi
2 (600 Å) and CoSi
2 (370 Å) films were sputtered by Xe ions at energies of 200 and 260 keV, respectively. The sputtering process was carried out either at room temperature (RT), or at elevated temperatures, placing the samples in the radiation enhanced diffusion regime. The sputtering yields of Si,
S
si, and that of the metals,
S
Nb or
S
Co, have been calculated from BS spectra. The measured ratios of the sputtering yields for both suicides,
S
si
S
Nb
and
S
si
S
Co
, imply that preferential sputtering of Si with respect to the stoichiometrical composition of these suicides had occurred.
S
si
S
Nb
is found to be about 13 and showed little change with dose and temperature.
S
si
S
Co
increased with both temperature or dose from about 4.3 for a dose of
5 × 10
16
cm
2
at RT to about 7.2 for
1 × 10
17
cm
2
at elevated temperature. These ratios are in contrast to that reported for CrSi
2 at high temperatures (i.e.
S
si
S
Cr
= 65
). Possible reasons are thought to be related to the high affinity of Si to oxygen contamination.