High device yield of resistive switching characteristics in oxygen-annealed SrZrO₃ memory devices

This paper reports the effects of rapid thermal annealing (RTA) on resistive switching (RS) characteristics and mechanisms of SrZrO₃ (SZO)-based memory devices. SZO thin films were deposited on LaNiO₃ (LNO) (100)/Pt/Ti/SiO₂/Si using radio-frequency magnetron sputtering and were followed by an RTA process in N₂, Ar, and O₂ ambients, respectively, at various temperatures for improving RS performance. Experimental results indicate that an SZO device annealed in O₂ at 600 °C (O₂-600) exhibits stable RS properties and has a high device yield (∼ 90%), a reliable retention characteristic (up to 1 × 10⁶s at 100 °C), and steady nondestructive readout properties (over 1.4 × 10⁴s at 100 °C). However, by increasing RTA temperature to more than 700 °C, random formation of LNO (110) precipitates on the bottom surface of SZO grains might shorten the effective thickness of the SZO thin films. Furthermore, a strong electric field possibly occurs at the region between Al top electrodes and low-resistivity LNO precipitates. It is speculated that an RS phenomenon, which occurs within SZO grains instead of on grain boundaries, easily leads to RS failure, further resulting in severe degradation of device yield in the O₂-700 and O₂-800 devices. When compared with other devices, O₂-600 SZO memory devices exhibit highly reliable RS characteristics.