Introduction of Tunneling Oxide and Oxidation Process Effects for Reliable Si-Compatible Resistive-Switching Random-Access Memory.

Resistive-switching random-access memory (RRAM) has gained a great deal of attention as an emerging memory suitable for massive data storage media and synaptic device applications. For low-power operation capability, eliminating the necessity of current compliance, tunneling oxide can be inserted as a tunneling layer in the conventional RRAM devices. In this work, we have systematically investigated the effects of SiO2 tunneling layer and its formation method on the reliability of a Si3N4-based RRAM device. The tunneling oxide layers were deposited by plasma-enhanced chemical vapor deposition (PECVD) and medium-temperature oxidation (MTO) and compared to a single-layer reference device. The devices with tunneling layers demonstrated reduced state current, and the device prepared by MTO exhibited superior endurance and retention. All of the devices demonstrated space-charge-limited current conduction in the high-resistance state. X-ray photoelectron spectroscopy revealed that the MTO oxide layer was chemically more stable, resulting in a difference in endurance characteristics.