Temperature Dependence Strategy for Achieving Enhanced Reflow-Capable MRAM with a Multi-Interface Structure

Abstract

In terms of practical applications, a performance bottleneck with spin-transfer-torque magnetic random-access memory (STT-MRAM) devices is evident at varying temperatures, notably with respect to data retention at warm temperatures and endurance under cold conditions. Effective strategies to enhance the STT efficiency should be targeted at broadening the applicable temperature range. In this study, multi-interface structured and optimized materials have been incorporated in the magnetic tunnel junction (MTJ) free layer to augment perpendicular magnetic anisotropy (PMA) and mitigate temperature dependence. The thermal stability factor of the MRAM test chip exceeded 40 at 260 °C, which is sufficiently high for 5× solder reflow. Moreover, the endurance was retained for 2 × 10⁷ cycles at room temperature. The enhanced PMA is effective in augmenting the read margin (TMR/Rp_CV), surpassing 30, a value that exceeds the typical sense amplifier (SA) requirement. These findings demonstrate significant potential for multi-interface MTJ and can serve as the basis for establishing an evaluation system for future spintronic chips.