Abstract: A substrate processing chamber, in which the chamber houses a domed pedestal for supporting a substrate inside the chamber and a clamp ring having a seat formed therein. The chamber also houses a lift mechanism configured to receive the substrate and move it in close proximity to the clamp ring so that, upon transfer on the substrate from the lift mechanism to the pedestal, the clamp ring functions to secure the substrate to the pedestal. The lift mechanism includes a support having lift fingers to hold and center the substrate. The clamp ring includes a seat having a substrate engaging surface, which receives and holds down the periphery of the substrate onto the domed pedestal. In use the substrate engaging surface defines an angle to the horizontal which is greater than or equal to the angle to the horizontal defined by a tangent to the domed pedestal at the point where the periphery of the substrate is held down onto the pedestal. Typically the angle to the horizontal defined by the seat is about 3.