A method for forming a via in an alumina protective layer on a structure such as a magnetic write head for use in perpendicular magnetic recording. A structure such as a magnetic pole, and or magnetic trailing shield, is formed over a substrate and is covered with a thick layer of alumina. The alumina layer can then be planarized by a chemical mechanical polishing process (CMP) and then a mask structure, such as a photoresist mask, is formed over the alumina layer. The mask structure is formed with an opening disposed over the contact pad. A reactive ion mill is then performed to remove portions of the alumina layer that are exposed at the opening in the mask, thereby forming a via in the alumina layer.