Investigation of Tm2O3 As a Gate Dielectric for Ge MOS Devices

Abstract

In this work atomic layer deposited Tm2O3 has been investigated as a high-k dielectric for Ge-based gate stacks. It is shown that when Tm2O3 is deposited on high-quality Ge/GeO2 gates, the interface state density of the gate stack is degraded. A series of post-deposition anneals are studied in order to improve the interface state density of Ge/GeOx/Tm2O3 gates, and it is demonstrated that a rapid thermal anneal in O2 ambient can effectively reduce the interface state density to below 5·1011 cm-2eV-1 without increasing the equivalent oxide thickness. Fixed charge density in Ge/GeOx/Tm2O3 gates has also been investigated, and it is shown that while O2 post-deposition anneal improves the interface state density, the fixed charge density is degraded.