Nanoscale germanium MOS Dielectrics-part II: high-/spl kappa/ gate dielectrics

In this paper, atomic layer deposition (ALD) and ultraviolet ozone oxidation (UVO) of zirconium and hafnium oxides are investigated for high-kappa dielectric preparation in Ge MOS devices from the perspectives of thermodynamic stability and electrical characteristics. Prior to performing these deposition processes, various Ge surface preparation schemes have been examined to investigate their effects on the resulting electrical performance of the Ge MOS capacitors. Interfacial layer-free ALD high-kappa growth on Ge could be obtained; yet, insertion of a stable interfacial layer greatly enhanced the electrical characteristics but with a compromise for equivalent dielectric thickness scalability. On the other hand, interfacial layer-free UVO high-kappa growth on Ge was demonstrated with minimal capacitance-voltage hysteresis and sub-1.0-nm capacitance equivalent thickness. Finally, the leakage conduction and scalability of these nanoscale Ge MOS dielectrics are discussed and are shown to outperform their Si counterparts