Ultralow Sub-1-nA Operating Current Resistive Memory With Intrinsic Non-Linear Characteristics

Sub-1-nA operating current conductive-bridge resistive memory devices showing pronounced rectifying behavior have been demonstrated in a cell structure consisting of Cu top electrode, atomic layer deposition Al₂O₃ switching film and polysilicon bottom electrode as an in-cell resistor. This ultralow current provides energy savings by minimizing write, erase, and read currents. Despite having such low currents, excellent retention, ON/OFF ratio, and endurance have been demonstrated. Devices programmed with <;1-nA peak current pass 6 h retention test at 85°C and show no significant degradation after 10000 write/erase cycles. Due to the partially formed filament, the devices at ON-state exhibit pronounced nonlinear I-V and current rectification-both factors are very beneficial for RRAM array operation. Multilevel storage can be obtained by controlling the filament shape through compliance current.