A study of dielectric breakdown mechanism in CoFeB/MgO/CoFeB magnetic tunnel junction

We examined the breakdown characteristics of a 1-nm-thick MgO barrier by measuring the time dependent dielectric breakdown (TDDB) and conducting atomic force microscopy (C-AFM) observation. We found that two different local conduction modes, the percolation path and Fowler-Nordheim (F-N) tunneling, contribute to dielectric breakdown. Furthermore, the operating voltage of magnetic tunnel junctions (MTJs) for maintaining reliability over ten years against dielectric breakdown was discussed.