A cylindrical pump baffle fitted to a semiconductor processing chamber is disclosed. The pump baffle contains a screen with bores therethrough to allow process gasses from the process chamber to be exhausted from the chamber at a reduced rate. This decreases process discrepancies to the wafer due to the prejudice of gas concentration as a result of the pressure differential imposed upon the gas and thereby the wafer brought about by the rapid and relatively unimpeded exit flow of process gasses when no restrictive member is in place. The pump baffle is also machined such that it does not block the placement and removal of wafers by the platform robot arm.