50 nm AlxOy ReRAM array retention characteristics before and after endurance

This work investigates resistive random access memory (ReRAM) data retention after different set/reset endurance cycles on a 50 nm Mega-bit-class Al_xO_y ReRAM array. The high resistance state (HRS) before forming and low resistance state (LRS) after forming show the best retention compared with after set/reset programming. When set/reset cycles increase, the LRS retention becomes better, whereas HRS retention gets worse, probably because the filament size becomes larger. Consequently, the retention time of ReRAM is degraded as the device is worn out and the error rate of HRS becomes dominant.