Embodiments of a sputter source for semiconductor process chambers are provided herein. In some embodiments, a sputter source for a semiconductor process chamber may include: a target comprising a magnetic material to be deposited on a substrate, the magnetic material including a front surface where material is to be sputtered and an opposing back surface; and an outer magnet disposed proximate a back surface of the target and arranged symmetrically with respect to a central axis of the target, wherein the target has an annular groove formed in the back surface of the target disposed proximate the outer magnet to reduce a magnetic permeability of a region of the target proximate the outer magnet, wherein the groove is an unfilled v-shaped groove having an inner angle greater than 90 degrees.