Ozone-assisted bi-layer lift-off stencil for narrow track CPP-GMR heads

摘要

A method for forming a bi-layer lift-off mask for use in fabricating GMR read-head sensors with trackwidths of less than 0.1 microns. The mask layers are formed symmetrically on each other, each layer of the mask having a novel dog-bone shape and the lower mask layer being substantially undercut relative to the upper mask layer. The central portion of the lower mask layer forms a narrow ridge that maintains the upper mask layer at a fixed height above a substrate, thereby avoiding problems associated with bi-layer lift-off masks of the prior art. The method of forming the lower ridge requires a carefully controlled undercutting of the lower mask layer, which is accomplished by using an ozone-assisted oxidation process.