Rapid thermal growth of silicon nitride films

Based on our growth model for thin thermal oxides, we have investigated the growth of thin silicon nitrides formed by rapid thermal processing in NH₃. It again was found that the dilution of the process gas (here NH₃) by the inert gas Ar has a big impact on the quality of the dielectric. The growth of thin nitrides therefore can be described analogous to that of thin oxides with the only difference that the process temperatures have to be shifted to higher values. The nitrides show leakage current densities which are significantly reduced compared to that of SiO₂ but their interface quality is not sufficient for MOS applications. In order to reduce the interface state density a short reoxidation of the nitride results in oxynitrides with D_it-values as low as that of dry thermal oxides. It will be shown that for EOT values of 1.5-2 nm the leakage current densities are four orders of magnitude below that of SiO₂ with the same thickness.