| Non-volatile memory (NVM) are broadly used in removable media storage, smart phones, solid-state drive, etc. and flash memory technology has been dominating NVM market for over 20 years. However, further scaling of flash memory beyond sub 20 nm node brings tremendous challenges in device performance. For further scaling of Non-Volatile Memory technology beyond flash memory devices, Resistive Random Access Memory (ReRAM) devices have been proposed as a promising candidate due to its superior device performance and CMOS compatible process flow.;This dissertation focuses on three aspects of ReRAM research, multi-level cell (MLC) storage capacity, ReRAM crossbar array integration, and ReRAM practical application. In MLC part, multi-step forming technology was developed to substitute traditional one step forming in which current overshoot was suppressed and four stable resistance states were obtained. A comprehensive electrical characterization was conducted and trade-offs among different states were studied. In the section detailing crossbar integration, switchable diode based ZnO ReRAM device was identified as one of the promising candidates. Ru/ZnO/TiN/W stack demonstrated forming-free, self compliance-current controlled, non-volatile, switchable diode type ReRAM characteristics in crossbar arrays which establishes potential application as high-density non-volatile memory. Finally, a complete voice cognitive system was built utilizing MLC ReRAM crossbar array to demonstrate functionality at the simulation level. With these contributions, this work has established solid guidance for future ReRAM fabrication and characterization as well as hardware system realization. |
