The characteristic of HfO 2 on strained SiGe

Abstract

The thermal stability of strained Si 0.8Ge 0.2 and Si devices with HfO 2 gate dielectrics prepared by atomic layer chemical vapor deposition is studied. The interfacial layer at the HfO 2/Si or HfO 2/SiGe interface changed after different annealing temperatures. The thickness of the interfacial layer increases with increasing annealing temperature due to the trace amount of oxygen in the chamber or at the HfO 2 dielectric. The capacitance equivalent thickness (CET) increases with increasing post-deposition annealing (PDA) temperature because of the increase of the interfacial layer. The interfacial trap charge densities ( D it) for the SiGe and Si devices with the PDA temperature of 600 °C are found to be 7.5×10 12 and 1.8×10 11 cm −2 eV −1, respectively. The electrical characteristics of the SiGe device are slightly inferior to the Si device due to the elemental Ge at the HfO 2/SiGe interface. Obvious crystallization of HfO 2 in SiGe devices with higher annealing temperature causes the raising of leakage current.