This letter presents a unique process to grow high quality ultrathin (∼60 Å) gate dielectrics using N2O (nitrous oxide) gas. Compared with conventional rapid thermally grown oxide in the O2, the new oxynitride dielectrics show very large charge-to-breakdown (at +50 mA/cm2, 850 C/cm2 for oxynitride compared to 95 C/cm2 for the control thermal oxide) and less charge trapping under constant current stress. Significantly reduced interface state generation was also observed under constant current stress and x-ray radiation. A secondary-ion mass spectroscopy depth profile indicates a nitrogen-rich layer at the Si/SiO2 interface, which can explain the improved integrity of oxynitride dielectric.
Chemical composition and growth kinetics of ultrathin SiO2 films formed by rapid thermal oxidizing Si substrates in N2O have been studied. Both Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) revealed nitrogen pile-up at the SiO2/Si interface. Nitrogen concentration at the oxide surface and throughout the bulk was found to be low, similar to reoxidized/nitrided oxides. The nitrogen 1s electron binding energy determined by XPS in the oxide also indicated that these nitrogen atoms were bonded to Si. Electrical characterization showed that N2O oxides exhibited less interface state generation under hot-electron stressing as compared with the control oxide. Growth kinetics study showed that after an initial stage of fast growth, the oxidation rate was reduced significantly due to the formation of a nitrogen-rich layer at the Si/SiO2 interface which blocked oxidant diffusion to the interface.
Growth kinetics of ultrathin SiO2 films formed by rapid thermal oxidizing Si substrates in N2O has been studied in this communication. Results show that the linear-parabolic law still can be applied to the oxidation of Si in N2O and the interfacial nitrogen-rich layers in these films result in oxide growth in the parabolic regime by impeding oxidant diffusion to the SiO2/Si interface even for ultrathin oxides. The parabolic rate constant B exhibits an activation energy of 1.42 eV, which is the activation energy for oxidant diffusion in the interfacial nitrogen-rich layer.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.