A systematic study on dry etching process of germanium for Ge 3D-FETs applications

In this study, reactive-ion etching (RIE) of Ge in different ambient was systematically investigated. Several dominant parameters (applied power, gas flow rate and gas compositions) during the etching were considered to improve the profile of 3D Ge structures. Besides, it was experimentally confirmed that to obtain Ge sidewalls with small roughness and a large angle, adding O2 and an appropriate masking material are important. Finally, by optimizing the process parameters, Ge sidewalls with an angle near 80° and smooth surfaces were successfully achieved.