Meeting the stringent image placement error budgets for 157 nn lithography in the sub-90 nn regime requires that mask-related distortions be minimized, corrected, or possibly eliminated. One of the sources of image placement error is the pellicle system. Static pellicle-induced distortions have previously been characterized, both experimentally and numerically. This article focuses on the dynamic response of modified fused silica (hard) pellicles during exposure scanning and takes into account inertia effects as well as fluid/structure interactions. Parametric studies were performed to identify conditions causing the pellicle behavior to become dynamic. Distortions of the 800-mum-thick hard pellicle for different acceleration pulse widths' were assessed, both numerically and analytically, and the agreement was excellent. The results presented here will facilitate the establishment of pellicle standards for 157 nm lithography.