US Patent 11923233 Dual-function wafer backside pressure control and edge purge

Apparatus and methods for providing backside pressure control and edge purge gas to a substrate in a processing chamber. A seal band within a pocket of a substrate support defines an inner pocket region and an outer pocket region. The seal band has a pressure dependent controlled leakage rate so that a backside gas flow to the inner pocket region can diffuse through the seal band to the outer pocket region to create an edge purge while providing backside pressure to the substrate. Processing chambers, methods of processing a substrate and non-transitory computer-readable medium containing instructions to process a substrate are also disclosed.