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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 × 106 s at 100°C), and steady nondestructive readout properties (over 1.4 × 104 s 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.
Date of Publication: April 2011