Emerging memories (EMs) have been intensively explored for embedded non-volatile memory (eNVM) applications because of their advantages over conventional eNVMs. There has been limited production of microcontrollers with embedded EM (eEMs) but the eEMs market has not taken off yet. The disruptive innovation undertaken by advanced digital CMOS technologies now provides a compelling motivation for a radical change, giving eEMs a great opportunity for success. Phase change memory (PCM) has been proven, in stand-alone memories, to be the most mature among the various kinds of EM. This paper illustrates the enormous potential of PCM in the field of eNVM. The evolution of embedded PCM (ePCM) is reviewed, showing evidence for the effort spent to enlarge the operating temperature range to cover an automotive mission profile. The recently disclosed state-of-the-art 28 nm HK metal gate fully depleted silicon-on insulator ePCM is presented as the demonstration of the ePCM potential to become the mainstream eNVM technology at 28 nm and below, at least for automotive grade applications. Finally, the opportunity for ePCM to play a relevant role in the field of edge artificial intelligence is briefly discussed.

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The effect of back-end of line (BEOL) process on cell performance and reliability of Phase-Change Memory embedded in a 28nm FD-SOI platform (ePCM) is discussed. The microscopic evolution of the Ge-rich GST alloy during process is the focus of the first part of the paper. A new metric for quantification of active material modifications is introduced to better follow its evolution with process sequence. Ge clustering has been shown to occur during the fabrication, impacting the pristine resistance and the after forming cell performance. Two different BEOL processes are then benchmarked in terms of key performance. An optimized process is identified, and an extensive electrical characterization of array performance and reliability is done on the full 16MB chip. The optimized BEOL process results in a memory cell fully compatible with the requirements for demanding automotive applications.

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