On dielectric breakdown in silicon-rich silicon nitride thin films

Abstract

Observations of dielectric breakdown in Si-rich silicon nitride indicate that it is initiated by threshold field trap ionization. The films exhibit the charge transport mechanism of Poole-Frenkel emission with a compositionally dependent ionization potential ranging from 0.58 to 1.22 eV. Similar to silicon oxynitride, the barrier lowering energy at the point of dielectric breakdown is correlated with within ∼2kT of the ionization potential, thus revealing a dual role for bulk traps in the film: regulating charge transport and retarding hot electron generation. Additionally, a semiempirical expression is developed that accurately predicts the compositional dependence of the breakdown field. © 2009 American Institute of Physics.