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

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 x 10(20) eV(-1) cm(-3) at 1.17 eV while the peak trap density extracted using retention model is 6.24 x 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. (C) 2009 The Japan Society of Applied Physics