Comprehensive study of Ultra-high density Resistive Random Access Memory (RRAM) devices and insulator-metal transition (IMT) selector devices

Abstract

Resistive random Access memory (RRAM) is one of the most attractive memory device because of its high scalability, high speed, high reliability (endurance, retention etc.), simple device structure and multi-level cell capability. In this study, Ultra high density RRAM are extensively studied. Moreover, to mitigate sneak path current problem in the crossbar array, IMT selector devices are also investigated thoroughly. CRS devices are also analysed as it can be used to bypass the use of selector device to avoid leakage current. In this study, Nitrogen doped TaOx based RRAM showed very good uniform current distribution, reliability and improved variability. Nitrogen confine the filament and improve the electrical characteristics. Several devices with different nitrogen flow are also extensively analysed and a proper guideline is suggested to achieve 3 bit MLC behaviour. Later 3-bit MLC devices are checked for the announced nitrogen range with the variability and reliability which shows excellent performance. Due to insufficient current density, higher off current, integration complexity, CMOS incompatibility, fabrication complexity of selector device, CRS devices are a good choice to the researcher. Ta/ TaOx/ N-TaOx/ Pt device are also analysed, which show excellent CRS behaviour, where device maximum current can be controlled by forming compliance current. Later, we investigate IMT characteristics of SmNiOx without using any high temperature and pressure during deposition, which was a trade of to use this material as a selector device for cross point array. ii We just form a nanoscale IMT region by electro thermal driven oxygen ion migration induced stabilization process. Excellent 1S1R characteristics and more experiment to investigate the device physics are also exhibited. We also demonstrated the IMT characteristics of NbOx which was prepared by DLI-CVD process. It is a great invention to effectively use the NbOx for scalable 3D integrated device.