Evaluation of Effective Thermal Stability Factor for Patterned Magnetic Tunnel Junction Array

Accurate and early estimation of the thermal stability factor of a memory array is essential for the development of modern non-volatile magnetic storage devices. We propose an evaluation method for effective array-level thermal stability factors (Δ
_eff
) via magnetic characterization of patterned magnetic tunnel junction (MTJ) arrays. These patterned arrays do not require traditional electrical contacts and circuitry that are usually needed for Δ
_eff
evaluation. Using vibrating sample magnetometer (VSM) at elevated temperatures and under applied fields, we demonstrate that these MTJ arrays exhibit a moment change trend that fits the Néel-Brown model and are able to extract the respective Δ
_eff
. The domain-wall-mediated reversal model is used to obtain zero-field Δ
_eff
. Using this method, we have optimized MTJ film stacks based on fast array-level feedback and validated high data retention of Δ
_eff
~ 46 at 260 °C from fully integrated MTJ bit arrays.