Embodiments of improved apparatus for maintaining low non-uniformity over the life of a target are provided herein. In some embodiments, an apparatus includes a substrate support within a volume of a chamber body, opposite a target assembly of a lid atop the chamber body, with a surface; a shield disposed within the chamber body comprising one or more sidewalls surrounding the volume, the shield extending downward to below a top surface of the substrate support, radially inward, and returning upward forming an extending lip; and a first ring having (i) a first portion comprising an opening having a ceramic isolator, disposed therein, resting on top of the extending lip, and (ii) a second portion extending away from the first portion toward the surface, wherein the substrate support, over a life of the target, is configured to raise and lower, relative to the first ring, a substrate disposed on the surface.