GROWTH AND FILM CHARACTERISTICS OF N2O AND NO OXYNITRIDE GATE AND TUNNEL DIELECTRICS

Film characteristics of thin oxynitride dielectrics grown in nitrous o xide (N2O) and nitric oxide (NO) gas ambients at 950 degrees C were in vestigated by secondary ion mass spectrometry, x-ray photoelectron spe ctroscopy, atomic force microscopy (AFM), and cross-sectional transmis sion electron microscopy. Compared to N2O oxynitride, NO oxynitride ex hibits very different surface chemistry, interface properties, and gro wth phenomena. NO oxynitride has the N-int sharply peaked on the Si su bstrate side of the interface, while it is broad and on the dielectric side of the interface for the N2O oxynitride. The N (1s) XPS results reveal a clear distinction between N2O oxynitride and NO oxynitride. N ear the Si/dielectric interface the NO oxynitride shows primarily Si=N bonds, while the N2O films showed a N (1s) binding energy peak that i s in between that of Si=N bonds and Si=N-O bonds. Further, the NO oxyn itride surface roughness as determined by AFM is lower than that of th e Si/SiO2 interface. The film characteristics of N2O and NO oxynitride s after reoxidation in O-2 ambient are different. An anomalous increas e in N-int content and a decrease in oxygen content of these oxynitrid es were observed as a result of reoxidation in oxygen ambient. These r esults are explained on the basis of changes in matrix composition of reoxidized oxynitride films.