Analysis of ion induced surface damage on silicon etched in a CF4 plasma

Abstract
Etchant residue and backscattered material have been observed on silicon surfaces etched in a CF4 plasma. In addition to chemical contamination, the surface is damaged by ion bombardment with dissociated CF4 ions. X‐ray photoelectron spectroscopy and reflection high‐energy electron diffraction were used to study the extent of the damage and how it correlates with surface contamination. At low ion energies, a well ordered crystal surface is observed in the presence of fluorine contamination. At higher ion energies (>400 V), the silicon surface is contaminated by backscattered nickel from an unshielded contact lead and the silicon surface becomes polycrystalline.