Patent ID: 8492169

Claim:
A method of forming a MTJ stack of layers in a magnetic device, comprising: (a) providing a substrate; (b) forming a synthetic anti-ferromagnetic (SAF) pinned layer on the substrate; (c) forming a tunnel barrier layer on the SAF pinned layer by a sequence of steps, comprising: (1) depositing a first Mg layer with a first thickness (t 1 ) on the SAF pinned layer; (2) performing a first radical oxidation (ROX) process that partially oxidizes the first Mg layer and leaves a certain number of unoxidized Mg atoms in a region adjoining the SAF pinned layer; (3) depositing a second Mg layer with a second thickness (t 2 ) on the partially oxidized first Mg layer where t 2 <t 1 ; (4) performing a second ROX process that oxidizes essentially all Mg atoms in the second Mg layer; and (5) depositing a third Mg layer on the oxidized second Mg layer; (d) sequentially depositing a free layer and a capping layer on the third Mg layer; and (e) performing an anneal process such that the third Mg layer becomes oxidized by a mechanism involving diffusion of oxygen from the oxidized second Mg layer into the third Mg layer.