Methods and apparatus for processing substrates are disclosed. In some embodiments, a process chamber for processing a substrate includes: a body having an interior volume and a target to be sputtered, the interior volume including a central portion and a peripheral portion; a substrate support disposed in the interior volume opposite the target and having a support surface configured to support the substrate; a collimator disposed in the interior volume between the target and the substrate support; a first magnet disposed about the body proximate the collimator; a second magnet disposed about the body above the support surface and entirely below the collimator and spaced vertically below the first magnet; and a third magnet disposed about the body and spaced vertically between the first magnet and the second magnet. The first, second, and third magnets are configured to generate respective magnetic fields to redistribute ions over the substrate.