Lithographic patterning and confocal imaging with zone plates

Zone-plate-array lithography (ZPAL) uses an array of zone plates, combined with an array of micromechanical mirrors or shutters, to pattern features on a substrate without a mask. In this article, we investigate the patterning characteristics of individual zone plates. We show patterns printed with pixel-dose modulation (gray scaling) and subpixel beam stepping. Using a combination of these techniques for linewidth control, edge placement, and proximity-effect correction, ZPAL can produce arbitrary patterns with features as small as the focal spot of a zone plate. We also demonstrate the use of zone plates in a confocal-microscopy mode for placing the substrate at the focus of the zone plates, and for imaging. Zone-plate-array scanning-confocal microscopy (ZPAM) could be useful for gapping and alignment in ZPAL, and possibly for wafer or mask inspection at deep ultraviolet wavelengths.