Highly scalable resistive switching memory in metal nanowire crossbar arrays fabricated by electron beam lithography

Abstract

Resistive switching memories (RRAMs) based on oxides are promising nonvolatile memories with numerous advantages in cell structure, switching speed, operation power, and fabrication process. To promote practical application, however, the scalability issue of RRAMs should be investigated. In this work, the maskless electron beam lithography (EBL) was used to fabricate very small structures in the electron beam resist layer, which were subsequently transferred to a metal and oxide film by the lift-off process. Metal nanowires with a minimum width of 9 nm and arrays with such nanowires were fabricated by optimizing the pattern design and by correcting the electron beam proximity effect. By combining three processes of EBL, film deposition, and lift-off, Ti/HfO2/Pt-based RRAM devices with a minimum size of 10 nm integrated into a crossbar array were successfully fabricated. The fabricated devices exhibit good memory performance, including low operation voltage, good endurance, retention, uniformity, and scalability.