Alternative surface passivation on germanium for metal-oxide-semiconductor applications with high-k gate dielectric

An alternative surface passivation process for high-k Ge metal-oxide-semiconductor (MOS) device has been studied. The surface SiH4 annealing was implemented prior to HfO2 deposition. X-ray photoelectron spectroscopy analysis results show that the SiH4 surface passivation can greatly prevent the formation of unstable germanium oxide at the surface and suppress the Ge out-diffusion after the HfO2 deposition. The electrical measurement shows that an equivalent oxide thickness of 13.5Å and a leakage current of 1.16×10−5A∕cm2 at 1V gate bias was achieved for TaN∕HfO2∕Ge MOS capacitors with the SiH4 surface treatment.