(Invited) A Confined Phase Change Memory for M-Type Storage Class Memory

Monday, 2 October 2017: 11:20
Chesapeake C (Gaylord National Resort and Convention Center)
W. Kim (IBM T.J. Watson Research Center), M. BrightSky (IBM T. J. Watson Research Center), T. Masuda (ULVAC Inc.), S. Kim (IBM T. J. Watson Research Center), R. Bruce (IBM T.J. Watson Research Center), F. Carta, G. Fraczak, A. Ray (IBM T. J. Watson Research Center), Y. Zhu (IBM Research Division, T. J. Watson Research Center), K. Suu (ULVAC, Inc.), and C. Lam (IBM T. J. Watson Research Center)
Phase Change Memory (PCM) is relatively mature emerging memory technology which shows promise for serving as a Storage Class Memory (SCM) which fills the gap between high speed DRAM and much slower NAND. However, most reported PCM cells show stuck-SET failure caused by elemental segregation or open failure (void formation) as their failure mechanisms. Because of these failure mechanisms, it has been challenging to achieve the endurance specifications needed for M-type SCM. In order to overcome these well-known failure mechanisms of PCM, we advanced the state of the art confined PCM cell with a thin metallic liner.

In this study, we present a robust high aspect ratio confined PCM cell which utilizes a dense nano-crystalline-as-deposited phase change material. The small pore structures were filled utilizing an in-situ metallic liner plus nano-crystalline ALD GST process. The tuned process for depositing and integrating the phase change material yields a void-free dense confined PCM inside the pore. This confined PCM with a metallic liner is found to be immune to classic endurance failure mechanisms. So, the highly reliable confined PCM yields a new record endurance (2x1012 cycles) and a fast programming speed of 80ns with 10x switching. In addition, we thoroughly investigate the excellent endurance of the novel confined PCM with a thin metallic liner. Experimental results confirm that both the proper metallic liner and the confined pore cell structure are required for a reliability advantage. This confined PCM cell has high potential of being incorporated as a M-type storage class memory with advanced memory technology node due to its outstanding endurance and fast set speed.