Wafer support system

The present invention relates to supports for wafers in semiconductor processing chambers and, more particularly, to a system for supporting a wafer above a susceptor within a chemical vapor deposition chamber. An apparatus for processing a substrate comprises a susceptor for supporting the substrate, an upper heat source spaced above the susceptor, a lower heat source spaced below the susceptor, and a controller. The controller provides power to the heat sources at a selected ratio between the sources. The controller is configured to vary the ratio during a high temperature processing cycle of a substrate to thereby vary the ratio of the heat provided by the heat sources during the cycle.