Methods and apparatus for controlling the ion fraction in physical vapor deposition processes are disclosed. In some embodiments, a process chamber for processing a substrate having a given diameter includes: an interior volume and a target to be sputtered, the interior volume including a central portion and a peripheral portion; a rotatable magnetron above the target to form an annular plasma in the peripheral portion; a substrate support disposed in the interior volume to support a substrate having the given diameter; a first set of magnets disposed about the body to form substantially vertical magnetic field lines in the peripheral portion; a second set of magnets disposed about the body and above the substrate support to form magnetic field lines directed toward a center of the support surface; a first power source to electrically bias the target; and a second power source to electrically bias the substrate support.