SIMS Study of Silicon Oxynitride Rapid Thermally Grown in Nitric Oxide

As the gate dielectric for ULSI MOS devices scales in the ultrathin regime, it is fabricated increasingly with silicon oxynitride instead of silicon dioxide films. One way to obtain silicon oxynitride films is the rapid thermal oxidation of silicon in NO (RTNO). Earlier RTNO growth studies were not sufficiently comprehensive as well as limited by temperature uncertainty and nonuniformity across the wafer. Using a state-of-the-art rapid thermal processing (RTP) system, RTNO growth characteristics at oxidation pressures of 100 and 760 Torr, oxidation temperatures from 900 to 1200 degreesC and oxidation times from 0 to 480 s were obtained and investigated. Anomalies in the growth characteristics were observed. It was also demonstrated that secondary ion mass spectrometry (SIMS) using the MCs+ method could be used to accurately determine the depth distribution of N in ultrathin silicon oxynitride films.