Model-Based Mask Data Preparation (MB-MDP) has been discussed in the literature for its benefits in reducing mask write times [1][2]. By being model based (i.e., simulation based), overlapping shots, per-shot dose modulation, and circular and other character projection shots are enabled. This reduces variable shaped beam (VSB) shot count for complex mask shapes, and particularly ideal ILT shapes [3]. In this paper, the authors discuss another even more important aspect of MB-MDP. MB-MDP enhances CD Uniformity (CDU) on the mask, and therefore on the wafer. Mask CDU is improved for sub-80nm features on mask through the natural increase in dose that overlapping provides, and through per-shot dose modulation. The improvement in CDU is at the cost of some write times for the less complex EUV masks with only rectangular features. But these masks do not have the basis of large write times that come from complex SRAFs. For ArF masks for the critical layers at the 20nm logic node and below, complex SRAFs are unavoidable. For these shapes, MB-MDP enhances CDU while simultaneously reducing write times. Simulated and measured comparison of conventional methodology and MB-MDP methodology are presented.