Kinetics and Mechanism of Nanostructures in Oxidation ofSi1-xGex Alloys

Abstract

We investigate the oxidation behaviour of Si1-xGex alloys(x = 0.05, 0.15, and 0.25). The oxidation of SiGe films withdifferent compositions was carried out in O2 (dry) atmosphere at800, 900 and 1000°C, respectively, for variouslengths of time. The thickness and property of the nanoparticle andnanolayer in oxide films and germanium segregation in oxidation of SiGealloys are measured by using a high precision ellipsometer. Theresults are in good agreement with the Rutherford backscatteringspectrometry, profile dektak instrument andhigh-resolution scanning transmission electron microscopy. Wefound that the Ge content in the oxide layer increases with the Gecontent in SiGe alloys, and that the Ge content in the oxide film decreases withthe increasing oxidation temperature and time. Rejection of Ge resultsin piling up of Ge at the interface between the growing SiO2 andthe remaining SiGe, which forms a nanometre Ge-rich layer. Substantialinterdiffusion of Si and Ge takes place in the remaining SiGe, whichleads to the complicated distribution of Ge segregation. We find ananometre cap layer over the oxide film after fast oxidation, in whichthere are many Ge nanoparticles. We analyse the kinetics and mechanismof the nanostructure of the oxide and Ge segregation in oxidation ofSi1-xGex alloys.