Enhanced stitching for the fabrication of photonic structures by electron beam lithography

Abstract
Large-area electron beam lithography tools pattern substrates as a series of writing fields that are stitched together. Pattern defects, termed stitching errors, can arise at field boundaries and these can have detrimental effects on device performance. These problems are exaggerated by substrate tilt. In this article, the authors demonstrate the application of a substrate tilt correction procedure to minimize stitching errors in the fabrication of photonic structures by electron beam lithography. The authors show that the magnitude of stitching errors is dependent on the position within the field boundary and is influenced by substrate tilt. Application of tilt correction procedures is shown to reduce stitching errors and give rise to a corresponding reduction in propagation losses in photonic wire waveguides. The authors show that the results of measured propagation losses arising from stitching errors are in good agreement with numerical results.

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