Oxidation structure/method to fabricate a high-performance magnetic tunneling junction MRAM

摘要

An MTJ (magnetic tunneling junction) MRAM (magnetic random access memory) has a tunneling barrier layer of substantially uniform and homogeneous Al₂O₃ stoichiometry. The barrier layer is formed by depositing Al on a CoFe layer or a CoFe-NiFe bilayer having an oxygen surfactant layer formed thereon, then oxidizing the Al by radical oxidation. The underlying surfactant layer contributes oxygen to the bottom surface of the Al, forming an initial amorphous Al₂O₃ layer. This layer produces small, uniform grains in the remaining Al layer, which promotes a uniform oxidation of the Al between its upper and lower surfaces by the subsequent radical oxidation. A final annealing process to set a pinned layer magnetization enhances the homogeneous oxidation of the layer.