A cleaning wafer cleans process residues from a support surface used in the processing of a substrate in an energized gas. The cleaning wafer has a disc having a liquid precursor derived polyimide layer formed directly on the disc by applying a liquid polyimide precursor to the disc. The polyimide layer has a thickness of less than about 50 microns, and a cleaning surface shaped to match a contour of the support surface. Process residues adhere to the cleaning surface and are cleaned from the support surface upon removal of the cleaning wafer therefrom.