High- k gate stack on germanium substrate with fluorine incorporation

Abstract

In this letter, a postgate C F4 -plasma treatment is proposed and demonstrated on germanium (Ge) metal-oxide-semiconductor capacitors and the effects of fluorine (F) incorporation have been studied on both high- kGe gate stacks without any surface passivation and with Si surface passivation. Our results show that F is effectively introduced into the gate stack by C F4 treatment and segregates near high- kGe interface. Electrical characteristics such as frequency dispersion, interface state density (Dit), and gate leakage are improved after F incorporation. Interface quality of high- kGe gate stack is further improved by combining Si surface passivation and postgate C F4 treatment, with its Dit as low as 4.85× 1011 cm-2 eV-1. © 2008 American Institute of Physics.