Lithographic characterization of the field dependent astigmatism and alignment stability of a 0.3 numerical aperture extreme ultraviolet microfield optic

Here we describe the lithographic characterization of the astigmatism in a 0.3-numerical aperture extreme ultraviolet (EUV) microexposure tool installed at Lawrence Berkeley National Laboratory. The lithographic results, measured across the field of view, are directly compared to EUV interferometry results obtained from the same tool at Berkeley during the optic alignment phase nearly one year prior to the lithographic characterization. The results suggest a possible long-term astigmatism drift on the order of 0.5nmrms. Moreover, the uncertainty in the lithographic characterization is shown to be approximately 0.1nmrms, similar to the precision previously demonstrated from EUV interferometry.