Overcoming Temperature Limitations in Phase Change Memories With Optimized ${\rm Ge}_{\rm x}{\rm Sb}_{\rm y}{\rm Te}_{\rm z}$

Phase change memory (PCM) is the most mature among the novel memory concepts. Embedded PCM technology can be a real breakthrough for process cost saving and performances. Nevertheless, for specific applications some improvement in high temperature data retention characteristics is needed. In this paper, we present an optimized GexSbyTez phase change material, able to guarantee code integrity after soldering thermal profile and data retention in extended temperature range. In particular, extrapolation of data retention at 10 years for temperatures higher than 150°C cell level has been demonstrated, thus enabling automotive applications. Despite the tradeoff between the SET speed and RESET data retention, competitive performances with respect to present floating gate memories have been confirmed. Finally, solid data collection based on a 4-Mb test chip integrated in a standard 90-nm CMOS technology platform has been performed. Functionality and performances are well in line with today industrial targets.

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