15.9 A 16nm 16Mb Embedded STT-MRAM with a 20ns Write Time, a 10<sup>12</sup> Write Endurance and Integrated Margin-Expansion Schemes
Ku-Feng Lin, Hiroki Noguchi, Yi-Chun Shih, Perng-Fei Yuh, Yuan-Jen Lee, Tung-Cheng Chang, Sheng-Po Huang, Yu-Fan Lin, Chun‐Ying Lee, Yen-Hsiang Huang, Jui-che Tsai, Saman Adham, P. Noel, Ramin Yazdi, Marat Gershoig, YangJae Shin, Vineet Joshi, Ted Wong, Meng-Ru Jiang, J. J. Wu, Chun-Tai Cheng, Yu-Jen Wang, Harry Chuang, Yu-Der Chih, Yih Wang, Tsung-Yung Jonathan Chang
Abstract
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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> 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.