Quantifying data retention of perpendicular spin-transfer-torque magnetic random access memory chips using an effective thermal stability factor method

The thermal stability of perpendicular Spin-Transfer-Torque Magnetic Random Access Memory (STT-MRAM) devices is investigated at chip level. Experimental data are analyzed in the framework of the Neel-Brown model including distributions of the thermal stability factor Delta. We show that in the low error rate regime important for applications, the effect of distributions of Delta can be described by a single quantity, the effective thermal stability factor Delta(eff), which encompasses both the median and the standard deviation of the distributions. Data retention of memory chips can be assessed accurately by measuring Delta(eff) as a function of device diameter and temperature. We apply this method to show that 54 nm devices based on our perpendicular STT-MRAM design meet our 10 year data retention target up to 120 degrees C. (C) 2015 AIP Publishing LLC.