D. Pedersen et al., SPUTTERING AND MIGRATION OF TRACE QUANTITIES OF TRANSITION-METAL ATOMS ON SILICON, Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms, 117(1-2), 1996, pp. 170-174
We have investigated the behavior of low levels of transition metal at
oms on silicon surfaces subject to nitrogen bombardment. Submonolayer
coverages of gold, iron, copper, molybdenum and tungsten were deposite
d on [100] silicon surfaces. Samples were analyzed using 270 keV He+ t
ime-of-flight backscattering before and after irradiation with 6 mC of
270 keV N+ at current levels in the hundreds of nanoamps. The yield o
f sputtered metallic atoms ranged from 1.0 X 10(-3) per incident nitro
gen ion to 3.3 X 10(-3) per incident ion. Lower yields were correlated
with migration of the metallic species into the silicon. The implicat
ions for ultra-high sensitivity measurement of contamination on silico
n wafers by time-of-flight heavy-ion backscattering spectrometry are d
iscussed.