Uniform durable thin dielectrics prepared by rapid thermal processing in an N2O ambient

Thin dielectrics grown on silicon wafers by rapid thermal processing in an N₂O ambient at temperatures of 1100°C, 1150°C, and 1200°C are discussed. The resulting films, in conjunction with an O₂ ambient control were characterized by thickness measurements and electrical performance. Dielectrics formed in N₂O in this temperature range were all superior to that prepared in an O₂ ambient in terms of interface state generation and flatband voltage shift after constant current stressing. Although all N₂O prepared samples exhibited similar cross wafer electrical uniformity, higher growth temperatures favored thickness uniformity. The electrical behavior of the N₂O wafers was not strongly dependent on growth temperature; however, a 60-s 1100°C post-oxynitridation N₂ anneal was found to significantly reduce subsequent electrical performance. It is also demonstrated that under optimum process conditions, high-quality uniform dielectrics can be formed by RTP in N₂O