Understanding and empirical fitting the breakdown of MgO in end-of-line annealed MTJs

In STT-MRAM, breakdown of the nanometer thin MgO barrier layer in Magnetic Tunnel Junctions (MTJ) is impacted by self-heating due to high operating currents. The simulated temperature increase at breakdown conditions can reach 200◦C, which dominates breakdown acceleration. The self-heating depends on area, which results in the absence of V BD -area scaling. In addition, process variability introduces variation in Resistance-Area product (RA) and critical dimension (CD), both impacting reliability. We propose an empirical model to fit both RA and CD dependence. This model offers a fair benchmark for stack and process optimization. Moreover, we demonstrate improved reliability for MTJs with W-based spacers and MTJs with end-of-line anneal at 400°C, 180 min.