Study of total ionizing dose induced read bit errors in magneto-resistive random access memory

This paper presents the Co-60 irradiation results for a 16 Mb Magneto-resistive Random Access Memory (MRAM). Read bit errors were observed during Total Ionizing Dose (TID) testing. We have investigated their physical mechanisms and proposed a resistance drift model of the access transistor in 1M1T (a magnetic tunnel junction and a transistor) storage structure to understand the phenomenon. Read operations have been simulated by HSPICE simulator with the magnetic tunnel junction (MTJ) compact model. The simulation results reveal that the resistance shift of access transistors has a great impact on read bit errors in MRAM. The experimental data and analysis in this work can be used to harden MRAM designs targeting space-borne applications.