R&D: Robust Thermal Stability in DRAM-Like Sb2Te-Based PCM by Hafnium Modified

Journal of Materials Science: Materials in Electronics has published an article written by Ruobing Wang, Zhenhui Yuan, State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China, and Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, 100049, China, Xin Chen, Sannian Song, and Zhitang Song, State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Micro-System and Information Technology, Chinese Academy of Sciences, Shanghai, 200050, China.

Abstract: “Phase change memory (PCM) has gained much attention as a candidate to draw closer to dynamic random access memory (DRAM). Here, the effect of Hf addition on the Sb₂Te is systemically studied. Doping Hf can remarkably increase the crystallization temperature from 151 to 230°C and 10-year retention temperature from 67 to 155 °C, showing superior thermal stability. The crystal grain size also is reduced significantly by doping Hf from 50 to 10nm. The PCM cell based on Hf_0.04(Sb₂Te)_0.96 can achieve reversible switching by applying even 10ns voltage pulse experimentally, also with good endurance over 10⁴ switching cycles. Through theoretical investigations, doped Hf atom prefer to be located at Sb atom positions and form Hf-centered octahedron with strong bonds, which may generate stress to inhibit the grain growth and act as precursors to boost the crystallization speed. Both the DRAM-like operation speed and excellent thermal stability making it a promising candidate for novel applications.“