The composition of ultrathin silicon oxynitrides thermally grown in nitric oxide

The thermal oxynitridation of Si(100) in nitric oxide (NO) has been studied by high resolution medium energy ion scattering for ultrathin films. The nitrogen depth distribution and the composition of the films have been accurately determined. It is observed that for NO-grown films the nitrogen is distributed relatively evenly in the film, unlike the sharply peaked distribution observed in the case of SiO2 films that were subsequently annealed in NO. The width Of the nitrogen distribution, as well as the oxynitride thickness, increase with temperature. It is further found that the total amount of nitrogen in the film and the ratio of nitrogen to oxygen increases with increasing oxynitridation temperature. These results have significant impact on our understanding of how nitrogen can be positioned in next-generation gate dielectrics. (C) 1997 American Institute of Physics.