Impact of nitrogen concentration profile in silicon oxynitride films on stress-induced leakage current

Stress-induced leakage currents of silicon oxynitride films (9 nm thick) with different nitrogen concentration profiles have been investigated. We found that leakage current at a gate electric field of approximately 6 MV/cm after electron injection (0.1-1.0 C/cm2 is reduced upon the incorporation of approximately 0.75 at% of nitrogen atoms near the oxynitride/Si interface. However, stress-induced leakage current increases with increasing nitrogen atom concentration at a depth of 1.5 nm in silicon oxynitride films. The optimum nitrogen atom concentration profile in silicon oxynitride films can decrease the number of tunneling sites and lead to small stress-induced leakage current at low electric field.