Improvement of charge trapping characteristics of Al2O3/Al-rich Al2O3/SiO2 stacked films by thermal annealing.

Abstract: Thin film Al2O3/Al-rich Al2O3/SiO2 structures were fabricated on p-Si substrates. Radio-frequency magnetron co-sputtering was used to form Al-rich Al2O3 thin film as the charge-trapping layer of nonvolatile Al2O3 memory. Capacitance–voltage measurements showed a large hysteresis due to charge trapping in the Al-rich Al2O3 layer. The charge trap density was estimated to be 42.7×1018 cm−3, which is the largest value ever reported for an Al-rich Al2O3 layer; it is six times larger than that of a conventional metal–nitride–oxide–silicon memory. Thermal annealing was found to reduce the leakage current of the Al2O3 blocking layer, thereby providing this structure with better data retention at room temperature than an as-deposited one. In addition, the annealed structure was found to exhibit good data retention even at 100°C. [Copyright &y& Elsevier]