Interface reaction kinetics in SiGe oxidation

Abstract

The oxidation of SiGe is very different from that of Si or Ge, leading to poor interface quality in oxidized SiGe gate stacks. In this work, SiGe oxidation kinetics and its effects on the generation of interface defects are discussed by considering the GeO desorption as well as Ge precipitation. Unlike GeO2/Ge, no GeO desorption associated with the reaction between GeO2 and Ge is detected in GeO2/SiGe below 700 °C. Instead, GeO desorption related to a reaction between GeO2 and Si is observed above 800 °C; however, it is suppressed by inserting a thin SiO2 layer on the SiGe surface. Based on experimental results and thermodynamic calculations, the SiGe oxidation kinetics is reconsidered in conjunction with the interface properties in SiGe gate stacks. The present results provide clear insights into a viable solution for high performance SiGe gate stacks.