Electron beam lithography writing strategies for low loss, high confinement silicon optical waveguides

The authors present a robust process for fabricating passive silicon photonic components by direct-write electron beam lithography (EBL). Using waveguide transmission loss as a metric, we study the impact of EBL writing parameters on waveguide performance and writing time. As expected, write strategies that reduce sidewall roughness improve waveguide loss and yield. In particular, averaging techniques such as overlap or field shift writing reduce loss, however, the biggest improvement comes from writing using the smaller field-size option of our EBL system. The authors quantify the improvement for each variation and option, along with the tradeoff in writing time.