Sputtering of Si with keV Ar⁺Ions. II. Computer Simulation of Sputter Broadening Due to Ion Bombardment in Depth Profiling

Abstract

The knock-in effect occurring in depth profiling by ion sputtering has been studied by computer simulation using the Monte Carlo method. Calculations based on the binary collision model have been applied for a sandwich-type thin boron impurity layer in silicon substrate under Ar+ ion bombardment. The result clearly shows that the knock-in effect results in a change in shape of original depth distribution of impurity atoms. The distribution becomes skewed toward the interior of the target, and the position of the peak shifts. Computer simulation has also suggested that sputter broadening can be affected by the sputtering yield, namely, less broadening occurs for a higher sputtering yield under given conditions. The present Monte Carlo calculation has described with considerable success the qualitative tendency of the dependence of the sputter broadening effect on the primary ion energy obtained in an experiment by Andersen et al.