Indications for an ideal interface structure of oxynitride tunnel dielectrics

Interface characteristics with respect to nitrogen-distribution and hydrogen-diffusion behavior were evaluated for two model tunnel oxides nitrided by NO and N₂O gas, respectively. Nuclear reaction analysis reveals a different resistance of the two interfaces against the approach by H, which allows us to correlate the characteristic N-distribution of the tunnel oxide with a H-diffusion barrier. From the relation between the interface structure and the electrical properties of the tunnel oxynitrides, we thus propose that the ideal interface structure of reliable tunnel oxynitride features a N-rich H-diffusion barrier layer in front of the oxynitride/Si interface.