SiO₂ film decomposition reaction initiated by carbon impurities located at a Si-SiO₂ interface

We have annealed Si-SiO2 structures at an elevated temperature in He(g) with SiO(g) added to the ambient. A SiO2 decomposition reaction that normally forms large voids in a thin SiO2 film during annealing in He(g) is not detected with the added SiO(g). Instead, chemically reactive SiC impurity sites which initiate the SiO2 decomposition reaction are found segregated along crystallographic planes in the substrate at the Si-SiO2 interface. The mechanism and technological importance of this interfacial reaction are discussed.