Sb2Te3–HfO2 composite films for low-power phase change memory application

Abstract

The effect of HfO2 on phase change characteristics of Sb2Te3 films for phase change memory (PCM) applications was investigated by in situ temperature dependence of electrical resistance measurement, X-ray diffraction, field emission scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. It is shown that HfO2 inhibited the crystallization of the amorphous Sb2Te3 films, which improved the long-term stability of metastable amorphous phase. Memory devices based on Sb2Te3–HfO2 composite films with HfO2 concentrations of 10 at.% and 15 at.% were successfully fabricated and characterized. The 15 at.% HfO2-based memory device exhibited lower reset voltage and power consumption compared with the 10 at.% HfO2- and Ge2Sb2Te5-based ones. The endurances exceeded 1.6×105 and 2.2×105 SET–RESET cycles for 10 at.% and 15 at.% HfO2-based memory devices, respectively, and the resistance ratio between RESET and SET states achieved two orders of magnitude for both memory devices. The Sb2Te3–HfO2 composite films, especially with HfO2 concentration of 15 at.%, could be one of the most promising materials for application in PCM devices.