Sophisticated techniques to accurately align patterns have been developed that predominantly address the overlay of proximal layers in layer-by-layer processes that are separated by short, micron-scale distances. However, in some applications such as in flat optics, accurate, 3D alignment of workpieces whose patterns may be separated by large distances is desirable. Here, we describe an alignment scheme based on the far-field of a cascade of metasurface elements suitable for accurately aligning patterns separated by millimeter-scale distances. By using an 850nm laser illumination, we demonstrate registration accuracies of 10nm laterally and 50nm axially for patterns separated by mm-scale distances.
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