Extraction of Energy Distribution of Nitride Traps Using Charge Pumping Method in Silicon-Oxide-Nitride-Oxide-Silicon Flash Memory

摘要

A new charge pumping method is developed and applied to extract the energy distribution of nitride traps in silicon-oxide-nitride-oxide-silicon (SONOS) flash memory. Based on the Frenkel-Poole emission model and the tunneling probability given by Wentzel-Kramers-Brillouin (WKB) approximation, we proposed an advanced model of charge pumping current for SONOS device having thick tunnel oxide (> 3 nm). The detection range of trap energy depth in our experiment conditions is 1.06-1.24 eV. The extracted trap density distribution in energy levels of the nitride layer of prepared sample shows the peak trap density of 1.21 × 10~(20) eV~(-1) cm~(-3) at 1.17 eV while the peak trap density extracted using retention model is 6.24 × 10~(19) eV~(-1) cm~(-3) at 1.32 eV. This difference of the peak trap density and energy level at the peak trap density is originated from different tunneling probability of tunnel oxide during the measurement.