Illumination uniformity and reproducibility in extreme ultraviolet (EUV) microfield exposure tools are critical to many aspects of the EUV lithography development task. Here, the authors present a scanning-field-averaging illuminator delivering consistent, uniform illumination to synchrotron-based microfield exposure tools. The system is integrated into the existing Fourier-synthesis custom coherence illuminator at the SEMATECH Berkeley microfield exposure tool and its effectiveness is demonstrated lithographically. Following the upgrade, the authors report a 6.5% peak-to-valley intensity variation across the full 200x600 mu m(2) wafer-side field of view. (c) 2007 American Vacuum Society.