The effect of redeposition on the ion flux dependence of Si dot pattern formation during ion sputter erosion

Abstract

We report an ion flux dependence study of the Si dot pattern formed on Si(100) by Ar+ ion sputtering with the ion energy being 1.5 keV, ion dose 5 × 1017 ions cm−2, and ion flux ranging from 280 to 1100 µA cm−2. Experimental results show that the lateral dot diameter d and the ion flux f basically follow the relationship of , and the surface roughness w decreases with increasing f in an exponential decay manner. Simulations based on a widely accepted continuum model, namely the noisy Kuramoto–Sivashinsky equation, reproduced the trend for d versus f but failed to explain that for w versus f. A redeposition consideration was then suggested. It is found that with this correction not only are the d–f and w–f relationships well explained, but the simulated surface morphology bears closer resemblance to the experimental one as well. The effect of redeposition becomes important for f> ∼130 µA cm−2 as derived in this work.