The present disclosure is directed an apparatus for regulating gas flow in a deposition chamber during a deposition process. The apparatus includes an interior wall that forms an accommodating portion that accommodates a wafer support structure and an exterior wall disposed opposite the interior wall. The apparatus further includes an upper surface, coupled to both the interior wall and the exterior wall, that has a plurality of openings therethrough. The plurality of openings are configured to distribute a flow of gas originating above the apparatus when the apparatus is positioned over a gas outlet port of the deposition chamber.