Embodiments described herein provide methods and apparatus used to reduce or substantially eliminate undesirable scratches to the non-active surface of a substrate by monitoring and controlling the deflection of a substrate, and thus the contact force between the substrate and a substrate support, during substrate processing. In one embodiment a method for processing a substrate includes positioning the substrate on a patterned surface of a substrate support, where the substrate support is disposed in a processing volume of a processing chamber, applying a chucking voltage to a chucking electrode disposed in the substrate support; flowing a gas into a backside volume disposed between the substrate and the substrate support, monitoring a deflection of the substrate, and changing a chucking parameter based on the deflection of the substrate.