THE COMPOSITION OF ULTRATHIN SILICON OXYNITRIDES THERMALLY GROWN IN NITRIC-OXIDE

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