The incorporation of nitrogen in oxides has been studied after furnace oxidation inN2O at 900 °C. We observe that nitrogen isremovedfrom the oxide bulk during oxidation inN2O, while simultaneously nitrogen is incorporated at the growingSi–SiO2interface. This results suggests that nitrogen incorporation involves a dynamic equilibrium between competing processes which causes both nitrogen incorporation and depletion. A chemical model for nitrogen removal is proposed based on a reaction with NO. Reaction energies, estimated from semiempirical quantum‐mechanical calculations, support the proposed model. ©1995 American Institute of Physics.