Microscopic mechanism of interfacial reaction during Si oxidation

The reaction of atomic oxygen at the SiO2/Si(1 0 0) interface is studied based on total-energy electronic-structure calculations. It is found that the reaction in which an O atom in the oxide inserts into the SiSi bond of the substrate is largely exothermic. The calculated energy barrier of 0.87 eV for this reaction is lower than the experimentally reported activation energy (2.0 eV) for the interfacial reaction in the dry oxidation. The results would help us clarify the microscopic mechanism of Si oxidation, especially in identifying the form of oxidant in the dry oxidation.