A substrate heater assembly for supporting a substrate of a predetermined standardized diameter during processing is provided. In one embodiment, the substrate heater assembly includes a body having an upper surface, a lower surface and an embedded heating element. A substrate support surface is formed in the upper surface of the body and defines a portion of a substrate receiving pocket. An annular wall is oriented perpendicular to the upper surface and has a length of at least one half a thickness of the substrate. The wall bounds an outer perimeter of the substrate receiving pocket and has a diameter less than about 0.5 mm greater than the predetermined substrate diameter.