Patterns with unconventional shapes are converted into filled polygons in the GDS description, which can be done in various ways (a). Not only it is important how patterns are defined by patterning objects, but also how those objects are scanned according to the filling algorithm applied. SEM images in (b) show apparently different pattern quality when islands are created using different approaches to fill the space around them (other parameters are the same: 30 kV, 57 pA Ga ions, 1 μs dwell time, 22 nm dwell distance, 500 repetition). The pattern on the right was processed by an e-beam lithography software connected to drive the ion beam, while the pattern on the left was filled by line scans that run intermittently along the whole width of the pattern. The sample material is single crystal silicon with native oxide on the surface.
