SiGe selective etching to enable bottom and middle dielectric isolations for advanced gate-all-around FET architecture

Abstract

Formulated chemical ACT® SG6xxx series demonstrated SiGe etching selective to SiGe with lower Ge concentration. SiGe etching rate on SiGe/Si multi-stack shown steep trend as a function of Ge concentration, resulting in 338 of selectivity between SiGe30% and SiGe15%. Also, apparent loss on SiN and SiO2 was not observed. Moreover, SiGe etch rate was not impacted by chemical flow in the beaker. It suggests reaction-controlled based etching, which leads to good within wafer uniformity in etching rate of 300mm wafer spin processing. In conclusion, ACT® SG6xxx series is a promising option for the formation of BDI/MDIs in Nanosheet, Forksheet and CFET.