Status and outlook of STT-MRAM development

MTJ stack is optimized for TMR at low RA region, high PMA and 400 degrees C post annealing capability. Atomic level smooth bottom electrode with 0.5A roughness was developed and positive effects on annealing capability and PMA was demonstrated. The scaling challenge of STT-MRAM read operation down to sub-10nm is discussed. Various contributing factors to the MTJ cell resistance variation were investigated with focus on MRAM cell variation due to advanced lithography patterning techniques. With SADP or DSA, the MRAM cell size can be scaled down to 18nm physical dimension with 4.2% sigma/mu cell area variation, good enough for sub-10nm technology node.