Radical oxidation of germanium for interface gate dielectric GeO 2 formation in metal-insulator-semiconductor gate stack

Abstract

GeO2 was grown by a slot-plane-antenna (SPA) high density radical oxidation, and the oxidation kinetics of radical oxidation GeO 2 was examined. By the SPA radical oxidation, no substrate orientation dependence of growth rate attributed to highly reactive oxygen radicals with low oxidation activation energy was demonstrated, which is highly beneficial to three-dimensional structure devices, such as multigate field-effect transistors, to form conformal gate dielectrics. The electrical properties of an aluminum oxide (Al2 O3) metal-oxide-semiconductor gate stack with a GeO2 interfacial layer were investigated, showing very low interface state density (Dit), 1.4× 1011 cm-2 eV-1. By synchrotron radiation photoemission spectroscopy, the conduction and the valence band offsets of GeO2 with respect to Ge were estimated to be 1.2±0.3 and 3.6±0.1 eV, which are sufficiently high to suppress gate leakage. © 2009 American Institute of Physics.