STMicroelectronics has been the leading proponent of phase-change memory (PCM) for embedded memory on microcontrollers, particularly for automotive applications. It has been championing the technology since at least 2017 and sampled microcontrollers on its own 28nm fully-depleted silicon-on-insulator (FDSOI) manufacturing process in 2018 (see ST samples MCU with embedded phase-change memory).
Up until the 40nm node the non-volatile memory of choice was flash but this has problems scaling below 40nm partly due to the need for high voltages and the die area occupied by charge pumps to implement high voltages.
Now ST and Samsung are proposing a migration to 18nm FDSOI for leading-edge microcontroller applications including always-on type applications.
Samsung Foundry offers both 28nm and 18nm FDSOI. The 28nm FDSOI has the option of embedded MRAM while the 18nm FDSOI has no embedded memory offering. It could be that Samsung is already manufacturing 28nm FDSOI-plus-PCM for ST and will also make 18nm FDSOI-plus-PCM for ST on customer proprietary basis.
But is also possible that Samsung will start to offer 18nm FDSOI-plus-PCM to its broader audience in the future. The authors describe the platform as meeting the performance target for next-generation MCUs.
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