15.9 A 16nm 16Mb Embedded STT-MRAM with a 20ns Write Time, a 10 12 Write Endurance and Integrated Margin-Expansion Schemes.

STT-MRAM has been demonstrated as a viable embedded non-volatile memory (NVM) with 20-year data retention at 150°C, a high write endurance (>1M cycles), and the ability to tolerate solder reflow [1]. However, for working memory applications, even higher endurance, fast write speed, and small memory size are necessary. By optimizing the magnetic-tunnel-junction (MTJ) stack for a lower write current, while relaxing retention requirements (e.g., 1 min @ 125°C), STT-MRAM can achieve a higher endurance (>10 ¹² cycles) and a smaller bit cell size. Therefore, STT-MRAM is a promising alternative to SRAM as a working memory solution, while also offering a higher memory density compared to SRAM-based solutions.