Magnetic transducer with bilayer pole piece structure with improved milling endpoint detection

Abstract

A magnetic transducer with a bilayer pole piece in which a first layer of material forms the body of the pole piece and a second layer forms the pole tip after milling is disclosed, along with a disk drive using the transducer. The bilayer pole piece is used in a method to improve the determination of the optimum stopping point for the ion milling using the optically observable process of the gap layer and P tip layer being milled off of the P protection layer forming a gradually disappearing halo. The process of making the head proceeds conventionally through plating of the P layer which in applicant's head is the layer which forms the body of P . The process of the invention deposits a P protection layer and then uses a photo lift-off technique to form a void in the P protection layer where the gap and the P and P tips will be formed, i.e., the zero throat region. An additional ferromagnetic layer (the “P tip layer”) is vacuum deposited in the void area to a thickness equal to the final desired pole tip height. The gap layer is deposited and the P tip is formed as in the prior art. Ion milling using the P tip as a mask is then performed as in the prior art with the exceptions: 1) that the P protection layer protects areas of the wafer which should not be milled; and 2) instead of milling a notch in the planar surface of P , only the excess of the P tip layer is required to be milled.