Surface Roughness Variation during Si Atomic Layer Etching by Chlorine Adsorption Followed by an Ar Neutral Beam Irradiation

Abstract

In this study, the etch rate and surface roughness during the Si atomic layer etching using and Ar neutral beam were investigated for Si(100) and Si(111). When the pressure (flux) and the Ar neutral beam irradiation time (dose/cycle) were lower than the critical values, the etch rate and the surface roughness were varied with pressure and Ar neutral beam irradiation time. When both pressure and Ar neutral beam irradiation time were higher than the critical values, the saturated etch rates of a monolayer per cycle of 1.36 and for Si(100) and Si(111), respectively, and the lowest surface roughness of 1.45Å close to the reference sample could be obtained. From these results, it is believed that the silicon etching is controlled by the coverage of silicon chloride during the adsorption by the Langmuir isotherm and the removal of the silicon chlorides by the Ar neutral beam dose/cycle .