Top Spin-Orbit-Torque Switching of Magnetic Tunnel Junction With In-Situ Efficiency Quantification

Spin orbit torque (SOT) magnetic random access memory (MRAM) has been regarded as a promising solution to overcome the ‘memory wall’ problem and led the way to better computing. However, conventional top-pinned SOT-MRAMs with perpendicular magnetic anisotropy (PMA) always suffer from the sidewall redeposition and over-etching problem during fabrications, as well as lower tunneling magnetoresistance than the bottom-pinned one. To address these problems, we reported a novel SOT-MRAM with PMA and bottom-pinned magnetic reference layer, realizing SOT switching by current flowing through top SOT channel with assistance of in-plane magnetic field. Such device, known as top-SOT PMA-magnetic tunnel junction (pMTJ), presents critical switching current density around 40 MA/cm² at 10 μs pulse width. In addition, we characterized the SOT efficiency directly in MRAM device and post-deposited top Pt electrode in top-SOT-pMTJ is demonstrated to be effective SOT source, inspiring flexible design of top-SOT-pMTJ stacks and fabrication process. The proposed structure with back-end-of-line compatible fabrication is anticipated to the mass production of high-performance SOT-MRAMs.