(Invited) Resistive Switching and Current Status of HfO2-based RRAM

Abstract

The integration of embedded non-volatile memory (eNVM) devices in a Si CMOSmanufacturing process requires to identify cost-effective process flow strategies and Si-CMOS compatible materials. Hafnium dioxide (HfO2) is a promising dielectric for future Resistive Random-Access Memory (RRAM) applications. Following the “More than Moore” (MtM) approach, the advantage is given by the fact that the back-end-of-line(BEOL) integration of HfO2-based metal-insulator-metal (MIM) memory cells allows acost-effective realization of embedded RRAMs. However, it still remains difficult in HfO2-based RRAM to further reduce energy dissipation and in addition to increasereliability for system-on-chip (SoC) applications. Hence, a detailed understanding of the atomic-scale mechanism and the identification of the material changes within the insulator are necessary. To address this issue, RRAM integration aspects were accompanied by fundamental materials research studies. First, non-destructive and in-operando Hard X-ray Photoelectron Spectroscopy (HAXPES) was performed to correlate the resistive switching effect with materials modifications at the Ti/HfO2 interface. The fundamental materials research insights were then transferred to integrated 1T1R devices in 4 kbit RRAM test arrays.