Authors: Ming‐Chun Hong, Ching Shih, Guan‐Long Chen, Yu‐Chen Hsin, Chen‐Yu Yang, Hsin‐Han Lee, Kuan‐Ming Chen, Yu‐Ho Kao, Tsai‐Yu Wu, Chiao‐Yun Lo, Sin‐You Huang, Cheng‐Yi Shih, Shan‐Yi Yang, I‐Jung Wang, Yao‐Jen Chang, Shih‐Ching Chiu, Yi‐Hui Su, Chih‐Yao Wang, Jeng‐Hua Wei, Shyh‐Shyuan Sheu, Wei‐Chung Lo, Shih‐Chieh Chang, Tuo‐Hung Hou
Published: 2025-04-10
Source: Full article
AbstractUnipolar magnetic random‐access memory (U‐MRAM) enables high‐density integration of the ultimate 4F2 one diode and one magnetic tunneling junction architecture, essential for future data storage. Compared to conventional bipolar switching, U‐MRAM can improve data storage density and reduce the overhead of peripheral circuits. While recent U‐MRAMs show promising memory properties, their stochastic switching requires complex write‐and‐verify steps to reduce the write error rate. This paper presents a novel design of U‐MRAM achieving reliable deterministic switching by employing a standard spin‐transfer torque (STT) MRAM structure and process flow. Deterministic unipolar and field‐free switching is engineered through the interplay of STT, Joule heating, and the tailored stray field. The underlying mechanism, design criteria, and process optimization strategies are comprehensively elucidated. The deterministic U‐MRAM exhibits promising memory properties, including low switching voltage (−0.44/−0.65 V), promising speed (100 ns), high endurance (>109), and long retention (>10 years), all without an external magnetic field.