Sputtering of chlorinated silicon surfaces studied by secondary ion mass spectrometry and ion scattering spectroscopy

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Abstract
We have studied the sputtering of chlorinated Si surfaces by 1‐keV Ne+ impact using secondary ion mass spectrometry and low‐energy ion scattering spectroscopy. Under steady‐state conditions of submonolayer Cl coverage, SiCl+x ions (x=0–3) are all observed with identical coverage dependence. Cross sections for removal of Cl from Si are independent of initial coverage in the submonolayer regime. Sputter cross sections increase from 0.5×10−15 cm2 at normal incidence to a maximum of 22×10−15 cm2 at ∼70° angle of incidence. Secondary ion yields are shown to be markedly dependent on the presence of recoil‐implanted Cl in the substrate. The details of Cl sputtering and Si removal processes in ion‐assisted etching suggest a major role for recoil implantation of Cl into the Si lattice in formation and removal of SiClx products in etching reactions.