Method and apparatus for backside deposition reduction by control of wafer support to achieve edge seal

An apparatus for processing a wafer, the apparatus comprising:

• a pedestal for supporting the wafer in the apparatus, wherein the pedestal includes a wafer-facing surface extending from a central axis to an outer edge;
• one or more wafer supports configured to extend from the pedestal to support the wafer above the wafer-facing surface, the one or more wafer supports symmetrically arranged about the central axis, each of the wafer supports being spaced from the central axis by about half or less than half of the radius of the wafer;
• and
• a controller configured with instructions for performing the following operations:
• (a) providing the wafer over the pedestal and the one or more wafer supports;
• (b) contacting a backside of the wafer with the one or more wafer supports to support the wafer above the wafer-facing surface;
• and
• (c) positioning the one or more wafer supports so that an outer edge of the wafer sags and substantially contacts a surface of the apparatus opposite the backside of the wafer so as to limit access by process gases to the backside of the wafer during a deposition process.