Influence of post-annealing on the electrical properties of metal/oxide/silicon nitride/oxide/silicon capacitors for flash memories

Abstract

We report the effect of post-annealing on the electrical properties of metal/oxide/silicon nitride/oxide/silicon (MONOS) capacitors. Four samples, namely as-deposited and annealed at 750, 850 and 950 degrees C for 30 s in nitrogen ambient by a rapid thermal process, were prepared and characterized for comparison. The best performance with the largest memory window of 4.4 V and the fastest program speed of 10 ms was observed for the sample annealed at 850 degrees C. In addition, the highest traps density of 6.84 x 10(18) cm(-3) was observed with ideal trap distributions for the same sample by capacitance-voltage (C-V) measurement. These results indicate that the memory traps in the ONO structure can be engineered by post-annealing to improve the electrical properties of the MONOS device.