A method and apparatus for detecting backside particles during wafer processing is provided. The method includes forming layers on a front side of a wafer, holding a backside of the wafer on a top surface of a chuck, cooling the wafer by ejecting gas toward the backside of the wafer and detecting the presence of particles on the backside of the wafer whiles ejecting the gas toward the backside of the wafer. The presence of particles is detected if the pressure of the ejected gas is outside of a predetermined range.