Radical oxidation of germanium for interface gate dielectric GeO_2 formation in metal-insulator-semiconductor gate stack

摘要

GeO_2 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 (Al_2O_3) metal-oxide-semiconductor gate stack with a GeO_2 interfacial layer were investigated, showing very low interface state density (D_(it)), 1.4 × 10~(11) cm~(-2)eV~(-1). By synchrotron radiation photoemission spectroscopy, the conduction and the valence band offsets of GeO_2 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.