Fully strained Si 0.75Ge 0.25 epitaxial films with HfSiO gate dielectrics for high mobility channel metal-oxide semiconductor devices

Abstract

The authors report on fully strained Si 0.75Ge 0.25 metal-oxide-semiconductor capacitors with HfSiO 2 high- k gate dielectric and TaN metal gate fabricated on Si substrates. Fully strained Si 0.75Ge 0.25 films are directly grown on Si substrates below the critical thickness. HfSiO 2 high- k gate dielectrics exhibit an equivalent oxide thickness of 13–18 Å with a permittivity of 17.7 and gate leakage current density lower than SiO 2 gate oxides by >100×. Interfacial oxide of the HfSiO 2/Si 0.75Ge 0.25 stack consists primarily of SiO 2 with a small amount of Ge and Hf. High performance SiGe field effect transistors are highly manufacturable with excellent electrical characteristics afforded by the fully strained HfSiO 2/SiGe gate stack.