Interface characteristic and performance optimization mechanism for HfOx-based RRAM devices

Abstract

The HfOx-based resistive random access memory (RRAM) is extensively researched for next-generation nonvolatile memory because of its high integration and excellent compatibility with CMOS technology. The interfacial characteristics, including interface state and series resistance, which impact the HfOx-based RRAM performance. However, a quantitative analysis about interface state and series resistance at metal/hafnium oxide (HfOx) interface is still scarce. The interface state and series resistance are related to the interfacial layer and oxygen vacancy concentration. In this work, we use the Ti/HfOx/Pt structural RRAM device with different oxygen contents to control the interfacial layer and oxygen vacancy concentration at metal/HfOx interface. The series resistance at the HfOx/Pt interface in the low resistance state (LRS) is obtained using the Schottky model, while the interface state density and time constant at the Ti/HfOx interface in the high resistance state (HRS) are extracted by frequency dependence of conductance. The results indicate that the device uniformity is improved by reducing the LRS series resistance and HRS interface state density. Furthermore, the device endurance in the HRS deteriorates with the decrease of the interface state time constant. Overall, the RRAM device performance is optimized by modulating the series resistance, interface state density, and time constant.