Nanoscale Ge fin etching using inductively coupled plasma for Ge-based multi-gate devices

In this paper, nanoscale germanium (Ge) fin etching with inductively coupled plasma (ICP) equipment by Cl2/BCl3/Ar gas is experimentally demonstrated. The impact of Cl2/BCl3/Ar gas ratio on etching induced Ge surface roughness, etch rate, sidewall steepness, uniformity and layout dependence are comprehensively investigated. The surface roughness is improved by increasing Ar flow rate. A nearly vertical Ge Fin is obtained by optimizing Cl2/BCl3/Ar gas ratio. By using silicon oxide as hard mask, 60nm-width Ge Fin array with height of 100nm is experimentally illustrated with high uniformity of etch depth and Fin width. Therefore, this method shows great potential for Ge-based multi-gate device fabrication.