Interfacial Perpendicular Magnetic Anisotropy in Sub-20 nm Tunnel Junctions for Large-Capacity Spin-Transfer Torque Magnetic Random-Access Memory

Magnetic tunnel junctions (MTJs) with interfacial perpendicular magnetic anisotropy (PMA) attract much attention due to their utilization in spin-transfer torque magnetic random-access memory (STT-MRAM). Large interfacial PMA provides high thermal stability, which is critical for large-capacity MTJ arrays. We investigate the thermal stability and interfacial PMA needed for STT-MRAM applications. A thermal stability factor of 75 is required for data retention time of 10 years, which implies an interfacial PMA value of 4.7 mJ/m² as device sizes scale down to 10 nm. Even though a small retention time (e.g., 1 ms) is sufficient in some applications, such as cache memory, an interfacial PMA greater than 3.1 mJ/m² would be necessary for 10 nm MTJ pillars. When read disturbance is taken into consideration, the PMA should be larger. These findings provide guidelines for the design of sub-20 nm MTJ devices for large-capacity STT-MRAM.