Single-Event Effects in STT MRAM

STT MRAM’s greater memory density and inherent radiation tolerance has made it an attractive non-volatile memory option for the space and radiation effects community. Two Single-Event Effects (SEE) in STT MRAM will be discussed, which are bit-flips due to magnetization reversal of the ferromagnetic layers [1] and a negative bit resistance shift caused by soft dielectric breakdown [2] . These SEE have a high Linear Energy Critical Threshold (LET > 53 MeV-cm 2 /mg) and hence a low error rate probability in space. Due to the observation of Single Event Functional Interrupts (SEFIs) for other MRAM manufacturers, a simplified method of device irradiation while the device remains unbiased in ESD foam allows decoupling of the Front End of Line (FEOL) transistor circuits from the Back End of Line (BEOL) memory elements. This method allowed recognition of the SEE as a p-MTJ effect. Simulation of SEFIs [3] using a laser will be briefly discussed.