Current-perpendicular-to-plane magnetoresistive device with oxidized free layer side regions and method for its fabrication

摘要

A current-perpendicular-to the-plane (CPP) magnetoresistive device has two ferromagnetic layers separated by a nonmagnetic spacer layer with the free ferromagnetic layer having a central region of ferromagnetic material and nonmagnetic side regions formed of one or more oxides of the ferromagnetic material. One type of CPP device is a magnetic tunnel junction (MTJ) magnetoresistive read head in which the lower pinned layer has a width and height greater than the width and height, respectively, of the overlying central region of the upper free layer, with the side regions of the free layer being oxidized and therefore nonmagnetic. The MTJ read head is formed by patterning resist in the shape of the free layer central region over the stack of layers in the MTJ, ion milling or etching the stack down into the free layer, and then exposing the stack to oxygen to oxidize the ferromagnetic material in the side regions not covered by the resist.