Asymmetric focused-ion-beam trimming of longitudinal and perpendicular write heads

A novel focused-ion-beam (FIB) head trimming technique is described. As compared to the conventional approach of a symmetric trim, an asymmetric process, whereby only one side of a write pole is FIB milled to achieve the target width, is demonstrated to be robust and advantageous. We use this technique for both longitudinal and perpendicular HGA-level head trimming, demonstrating excellent recording performance out to areal densities of more than 100 Gb/in².