Abstract
Conventional FLASH memory is facing technological bottlenecks to scale down to sub-20 nm nodes, and its unsatisfactory endurance (~10^6 cycles) and long programming time (~1 us) have not been effectively improved. Resistive random access memory (RRAM) is a promising candidate to replace FLASH memory due to its excellent scalability (<10 nm), simple structure, fast switching speed (<10 ns), robust endurance (>10^10 cycles), long retention (>10 years), and good compatibility with CMOS front- and/or back-end-of-line processing. In addition, RRAM devices can be integrated in cross-point arrays, and their memory density can be further increased by three-dimensional stacking. For high-density cross-point memory applications, the challenges of RRAMs will be their variability and cell structure design. Thus, a textured material technology is proposed to reduce switching variability of ZnO-based RRAMs. In addition, ZnO- and Ta2O5-based cell structures are proposed for reducing sneak-path leakage. Furthermore, array size limitations and power consumption are investigated regarding different current-voltage (I-V) nonlinearity and read schemes.