A process chamber for depositing a film on a wafer is provided, including: a pedestal having, a central top surface having a plurality of wafer supports configured to support the wafer at a support level above the central top surface, an annular surface at a step down from the central top surface; a carrier ring configured to be supported by carrier ring supports such that a bottom surface of the carrier ring is at a first vertical separation above the annular surface, the carrier ring having a step down surface defined relative to a top surface; wherein when the carrier ring is seated on the carrier ring supports, then the step down surface of the carrier ring is positioned at a process level that is at a second vertical separation from the support level over the top surface of the pedestal.