N_2O oxidation kinetics of ultra thin thermally grown silicon nitride: an angle resolved x-ray photoelectron spectroscopy study

摘要

The oxidation kinetics of ultra thin thermally NH_3N_4 films in N_2O ambient has been extensively studied using angle resolved x-ray photoelectron spectroscopy (ARXPS). Ultra thin (7A) Si_3N_4 films formed by RTP nitridation of Si in NH_3 were annealed in N_2O at various temperatures (700 ~oC - 1000 ~oC) for 30 sec. ARXPS showed that Si substrate at the SiSi_3N_4 interface was oxidized when annealed at 1000 ~oC for 30 sec, and was accompanied by the oxidation of the top Si_3N_4 surface. The total film thickness increases 4approx5 times of that of the original Si_3N_4 layer. However, the oxide formed on the top Si_3N_4 surface is twice as thick as that formed at the Si_3N_4/Si interface. No interfacial oxide was found when annealing below 900 ~oC, although the formation of the silicon oxide and oxynitride above the Si_3N_4 layer was still observed.