An air platen assembly is described and includes a platen that has a plurality of concentric rings. Each of the rings has a plurality of openings in order to provide a cushion of air to a CMP belt. At least one of the rings extends beyond an outer edge of a wafer to be planarized by the CMP belt. A support is attached with the platen and has a plurality of air ports for pressurized air to pass to the rings of the platen. A gasket is positioned between the support and the platen and has a plurality of cutouts that align with the openings and the air ports. A base is also included and supports the support.