The purpose of this research. is to assess the effectiveness of electrostatic chucks in reducing low-spatial frequency mask (or reticle) flatness variations and to validate finite element (FE) models of the chuck-mask interaction. The flatness of a sample extreme ultraviolet lithography reticle and an electrostatic pin chuck were measured using a Zygo interferometer. The measured flatness data were entered into the FE models, and electrostatic chucking was simulated by applying an area-weighted average pressure on the reticle. The shape of the mask when clamped by the electrostatic chuck was then predicted using the FE model. To validate these predictions, experiments were conducted in which the previously measured reticle was electrostatically clamped using the pin chuck. These experiments were conducted in. a vacuum chamber to minimize the effects of humidity. Interferometric plots of the chucked reticle surface were obtained and compared with the FE predictions. It was found that the measured and predicted shapes were in good agreement: Results from the experiments and simulations will be used to establish specifications for the chuck design and to identify the range of flatness variations that can be accommodated with electrostatic chucking. (c) 2006 American Vacuum Society.