Magnetic tunnel junction reliability assessment under process variations and activity factors and mitigation techniques

Time Dependent Dielectric Breakdown (TDDB) is a major concern for the reliability of magnetic tunnel junctions (MTJs) in Spin-Transfer Torque RAM (STTRAM). We provide a breakdown model to capture the MTJ lifetime under dynamic read/write activity factors. We also propose static and dynamic current throttling coupled with circuit and system level techniques to improve the MTJ reliability at the cost of small performance penalty. Simulations using SPLASH benchmarks demonstrate ∼10¹⁰× improvement in MTJ reliability of the most frequently accessed cache sets for a minor IPC loss of ∼1.3% for dynamic throttling and ∼2% for static throttling under process variations.