Efficient exposure of non-Manhattan layouts for optical applications using variable shaped beam lithography

Background: Variable shaped beam systems offer high performance for common Manhattan layouts using rectangular or axis-parallel triangular exposure primitives. Emerging optical applications often consist of numerous non-Manhattan structures. The common processing modes for slanted or curved structures result in high shot counts and thus large write times.Aim: A sophisticated approximation approach for arbitrary non-Manhattan layouts is needed. For repetitive non-Manhattan layouts, the use of cell projection (CP) should be considered.Approach: The JES-approximation of data preparation software ePLACE is introduced and compared to common border approximation. CP in combination with ePLACE's target geometry feature is studied. The different approaches are assessed in optical quality and throughput.Results: Haze measurements of diffractive axicons verify the good optical quality of JES-approximation at moderate write times. Further improvements are enabled by mathematical input approximation (MIA). Scanning electron microscope (SEM) measurements of dot CP arrays validate the functionality of the target geometry approach for fine CD tuning. Write time studies confirm superior throughput results using CP in the exposures.Conclusions: For arbitrary non-Manhattan layouts JES/MIA-approximation should be applied. For repetitive non-Manhattan layouts, CP exposure is the best solution.