Patent ID: 7258809

Claim:
A method of selectively patterning a magnetic film structure comprising: (a) providing a magnetic structure comprising at least one pinned bottom magnetic film layer and at least one top magnetic film layer, wherein said at least one top and said at least one pinned bottom magnetic film layers are separated by a tunnel barrier layer, and said at least one top magnetic film layer having a passivating layer located thereon; (b) forming a patterned resist atop said passivating layer, wherein a portion of said passivating layer is exposed; (c) selectively etching said exposed portion of said passivating layer by a RIE process to expose a portion of said at least one top magnetic film layer; and (d) selectively etching said exposed portion of said at least one top magnetic film layer, and underlying portions of said tunnel barrier and said at least one pinned bottom magnetic film layer by a wet etch process which includes an etchant solution comprising an arylsulfonic acid and an aliphatic or alicyclic amine.