An MRAM device, and a process for manufacturing the device, provides improved breakdown distributions, a reduced number of bits with a low breakdown voltage, and an increased MR, thereby improving reliability, manufacturability, and error-free operation. A tunnel barrier is formed between a free layer and a fixed layer in three repeating steps of forming a metal material, interceded by oxidizing each of the metal materials. The oxidization of the third metal material is greater than the dose of the first metal, but less than the dose of the second metal. The fixed layer may include a discontinuous layer of a metal, for example, Ta, in the fixed layer between two layers of a ferromagnetic material.