Multilevel programming reliability in Si-doped GeSbTe for Storage Class Memory

Phase-Change Memory (PCM) demonstrated to be a mature Non- Volatile Memory technology to address Storage Class Memory (SCM) applications that can be distinguished in memory-type (M-SCM) and storage-type (S-SCM). In this work, we present how aGeSbTe (aGST) alloy can address both SCM types, in particular using Si doping. Thanks to the electrical characterization of 4 kb PCM arrays, we show how Si doping in aGST helps tuning the crystallization dynamic during the programming operations, leading to highly reliable intermediate resistance states. We support our results by TEM analyses and finally we present improved multi-level cell (MLC) operations in Si-doped devices, achieved already with a simple double-step protocol. We demonstrate the aGST alloy suitability for SCM applications: undoped alloy allows targeting M-SCM thanks to its high endurance and high programming speed, whereas Si-doped aGST featuring MLC capability and improved data retention can address S-SCM specifications.