SiGe pMOSFETs Fabricated on Novel SiGe Virtual Substrates Grown on 10um x 10um Pillars

Abstract

Silicon germanium pMOSFETs have been fabricated on novel silicon germanium virtual substrates. The SiGe virtual substrates were grown by MBE on 10µmx10µm silicon pillars fabricated by dry etching trenches into the original silicon substrate. The pillars promote relaxation of the SiGe virtual substrate and reduce cross hatch on the wafer surface.The devices have 5nm silicon germanium active layer with a germanium content of 70% grown on top of a relaxed virtual substrate with a germanium content of 30%. A 2nm silicon cap separates the SiGe channel from the gate oxide.Device characteristics show a improvement in on state drive current in these SiGe devices of 40% over their conventional silicon counterparts.