Investigation of Passivation of Ge Substrate by N2O Plasma and N2 plasma Treatment

Abstract

In this paper, passivation of Ge substrate by N2O plasma is proposed and compared with N2 plasma treatment. Results show that both N2O and N2 plasma treatment can improve the quality of the interface between high K dielectric and Ge substrate and the CV characteristics of MOS capacitors. Results show that, stoichiometric GeO2 is achieved by N2O plasma oxidation and GeOxNy is formed by N2 plasma treatment, due to native oxide residue or oxidation after aqueous cleaning. Comparing to GeOxNy passivation, GeO2 passivation is superior in reducing interface state density to ~2×1011cm-2eV-1, suppressing EOT degradation and modulating the surface potential, which is promising for high performance Ge NMOSFETs fabrication.