Publications

Onset of dielectric breakdown in LPCVD silicon oxynitride thin films

Habermehl, Scott D.; Apodaca, Roger A.

Charge transport and dielectric breakdown is studied in silicon oxynitride films with optical index of refraction varying from 1.77 to 2.01, and thickness ranging from 20 to 50 nm. Assuming Poole-Frenkel emission as the dominant charge transport mechanism, a compositionally dependent ionization potential ranging from 1.22 to 1.51 eV is observed. Over the same composition range, the barrier lowering energy at the point of dielectric breakdown is independently determined to vary between 1.24 and 1.56 eV. The correlation between these energies suggests a causal relationship between field saturation-induced trap ionization and dielectric breakdown. It is concluded that in the vicinity of the field saturation point a diminished capacity for regulating hot electron injection via the action of charge trapping results in an increased probability for impact ionization and subsequent dielectric breakdown.