Low write power and Field-free sub-ns write speed SOT-MRAM cell with Design Technology of Canted SOT structure and Magnetic Anisotropy for NVM

We evaluated and designed the canted angle and magnetic properties of canted spin-orbit torque (SOT) MRAM cells fabricated in a 300mm CMOS fully compatible process. In the results, we demonstrated that 75°-canted SOT devices as SOT-MRAM cell reduced the write power at 0.35 ns field-free writing by 35% and 20% compared to 30°-canted SOT devices [1] and Type Y SOT devices [2], respectively. We also achieved the world's lowest write power of 156 fJ in SOT devices, thanks to the advanced design of both 75°-canted SOT devices and optimized magnetic anisotropy of the MTJ which maintained a large thermal stability factor (Δ) of 70 and a high TMR ratio of 170%. From a viewpoint of stable writing operation at sub-nanosecond, we demonstrated that at a WER of 1E-4 in 0.8 ns writing, the 75°-canted SOT device achieved a lower current density of 20.8 MA/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, which is 43% and 22% lower than the 30°-canted SOT device and the Type Y SOT device, respectively. This study would provide guidelines for the development of canted SOT-MRAM with low power, high speed, and field-free writing.