Germanium incorporation in Hf O2 dielectric on germanium substrate

Abstract

It is widely reported that a significant amount of germanium is incorporated in Hf O2 gate dielectric during the formation of high- κ gate stack on germanium substrate. In this paper, the dependences of germanium incorporation in Hf O2 on dielectric deposition method, annealing temperature, and annealing ambient were extensively studied by physical methods such as time-of-flight secondary ion mass spectroscopy. The results indicate that the high thermal budget of processes, including deposition and annealing, is the most critical factor to the Ge incorporation. The Ge incorporation in Hf O2 is identified by two mechanisms: Ge atoms out-diffusion from substrate and gaseous GeO diffusion downward into Hf O2 via airborne transportation in the chamber. © 2006 The Electrochemical Society. All rights reserved.