Uniform switching behavior of HfOx-based memory with gradual-grown filaments by interface modulation

Abstract

HfOx/Cu/HfOx structures with Ti electrodes were fabricated to investigate the resistive switching characteristics. Stable and uniform switching behaviors can be observed for HfOx/Cu/HfOx sample except the few cycles at the beginning. XPS depth profile of the structure was carried out to explore the role of interface layer on chemical composition of HfOx film and the defects in the films were analyzed. In addition, the resistance in LRS was insensitive to device area. The processes of growth and dissolution of conductive filaments in HfOx film during switching cycles were investigated. The undissolved filaments in the bottom part of HfOx film promoted the growth of filaments in the subsequent set process. As the fixed Vos filaments and stable residual Cu filaments which can act as a precursor in upper and bottom part of the sample were formed, excellently uniform distribution of switching parameters can be obtained. Meanwhile, good endurance and retention properties can be observed for HfOx/Cu/HfOx sample. The migration of Vos and diffusion of Cu atoms under electric field were both responsible for the resistive switching behavior for HfOx/Cu/HfOx sample, and the underlying physical model of conductive filaments was proposed to illustrate the switching mechanism of HfOx/Cu/HfOx sample.