High thermal stability Sb3Te-TiN2 material for phase change memory application

Abstract

For phase change memory (PCM) applications, it has been widely accepted that δ phase Sb-Te has fast operation speed and good phase stability. However, the fast growth crystallization mechanism will cause poor amorphous phase stability and overlarge grain size. We introduce TiN2 into δ phase Sb-Te (Sb3Te) to enhance the amorphous thermal stability and refine the grain size. With TiN2 incorporating, the temperature for 10-year data retention increases from 79 °C to 124 °C. And the grain size decreases to dozens of nanometers scale. Based on X-ray photoelectron spectroscopy and transmission electron microscopy results, we knew that nitrogen atoms bond with titanium, forming disorder region at the grain boundary of Sb3Te-TiN2 (STTN). Thus, STTN has a quite different crystallization mechanism from Sb3Te. Furthermore, PCM device based on STTN can realize reversible phase change under 20 ns electrical pulse.