Isotope Tracing Study of GeO Desorption Mechanism from GeO₂/Ge Stack Using ⁷³Ge and ¹⁸O

Abstract

GeO desorption from a GeO 2 /Ge stack is a critical concern in Ge metal oxide semiconductor field effect transistors (MOSFETs). In this contribution, we focus on a uniform-desorption region and unveil the GeO desorption mechanism from a GeO 2 /Ge stack by 73 Ge and 18 O isotope tracing in thermal desorption spectroscopy (TDS) analysis, in which the Ge and O diffusion kinetics in GeO 2 and the interfacial reaction kinetics have been investigated. Through 73 Ge isotope tracing, we have clarified that Ge in the desorbed GeO dominantly comes from the GeO 2 surface. Moreover, the self-diffusivity of oxygen was evaluated to be much larger than Ge in GeO 2 . Furthermore, owing to the difference among GeO desorptions from GeO 2 /Ge stacks with various substrate orientations, the reaction at the GeO 2 /Ge interface was attributed to the redox reaction kinetics. On the basis of our experimental findings, we have proposed an oxygen vacancy diffusion model of the GeO desorption mechanism.