The present invention relates in general to resistive switching devices (RSDs). More specifically, the present invention relates to fabrication methods and resulting structures for forming a three-dimensional vertical array of RSDs configured and arranged to provide a tunable oxygen vacancy concentration.
Resistive random access memory (ReRAM) is a nano-scale non-volatile memory (NVM). ReRAM provides simple storage cell components, high density, low power, large endurance, fast write/read/erase speeds, and excellent scalability. A typical ReRAM storage cell is two-terminal device formed as a metal-insulator-metal (MIM) structure. The insulator material can be a binary metal oxide, which makes the MIM storage cell compatible with silicon-based CMOS (complementary metal oxide semiconductor) fabrication process. When a sufficient electrical field or signal is applied across the metal electrodes of a MIM, the resistance of the insulator can be switched from one resistance state to another through various mechanisms, including the formation and rupture of conductive filaments in the metal oxide. The oxygen vacancy concentration (VO) in the oxide of the binary metal oxide and the state of the insulator/electrode interface are significant factors in controlling the resistive switching mechanism in a MIM memory cell. The insulator retains its resistance state until an appropriate electrical signal is applied across the MIM metal electrodes to change it.