Multi-temperature deposition scheme for improved resistive switching behavior of Ti/AlOx/Ti MIM structure

Atomic layer deposited AlOx based resistive random access memories were fabricated with a new multi-temperature deposition (MTD) scheme, where a 40 nm thick AlOx film was deposited with temperature-thickness sequence of 150 degrees C (10 nm)/80 degrees C (20 nm)/150 degrees C (10 nm). Electrical characteristics of thus fabricated devices demonstrate improved bipolar resistive switching behavior with lower set and reset voltages of 0.65 V and -1.15 V respectively, decent repeatability of 75 cycles, reliable data retention upto 10(3) s, small variation of 0.29 V and 0.17 V in set and reset voltages respectively, and symmetric current-voltage curves. The conduction mechanism has been explained as ohmic and space charge limited conduction at lower and higher voltages respectively. Due to different deposition temperature, oxygen vacancy concentration was different in each layer of the MTD film, which led to formation of a conductive filament with nonhomogeneous strength and dimensions across the film. Localization of effective switching phenomenon in the region with weaker conductive filament yielded an improved performance with lower switching voltages in corresponding multi-temperature devices.