Reliable multi-level memristive neuromorphic devices based on amorphous matrix via quasi-1D filament confinement and buffer layer

Abstract

Conductive-bridging random access memory (CBRAM) has garnered attention as a building block of non-von Neumann architectures owing to scalability and parallel processing on the crossbar array. To integrate CBRAM into the complementary metal-oxide-semiconductor back-end-of-line, amorphous switching materials have been widely investigated for practical usage rather than crystalline materials. However, both the inherent randomness of filaments and disorders of amorphous material lead to poor reliability. In this study, a highly reliable nanoporous-defective bottom layer(NP-DBL) structure based on amorphous TiO2 is demonstrated (Ag/a-TiO2/a-TiOx/p-Si). The stoichiometries of DBL and the pore size can be manipulated to achieve both the analog conductance updates and multi-level conductance by 300 states with 1.3% variation, and 10 levels, respectively. Compared with non-porous TiO2 CBRAM, endurance, retention, and uniformity can be improved by 106 pulses, 28-days at 85℃, and 6.7 times respectively. These results suggest even amorphous-based systems, elaborately tuned structural variables can help design more reliable CBRAMs.