Energy and cost efficient manufacturing of uniform periodic nanostructures enabled by an adaptable beam flattening device

Abstract

High-precision fabrication of nanoscale periodic structures is utilized in a wide range of applications, including wire grid polarizers, photonic crystals, and light-emitting diodes. Among the fabrication methods, laser interference lithography (LIL) is one of the most widely applied techniques for nanoscale periodic structures, due to its advantages of being maskless, low cost, having an infinite depth of focus, and the capability of large-area patterning with a single exposure. However, since LIL requires uniform illumination of the coherent laser light, the illuminating laser beam is typically expanded and only the central part with uniform intensity is used, rendering LIL low in energy efficiency. In this study, we introduced a simple and cost-effective design of beam-flattening device with tunable performance that improves the energy efficiency and throughput of LIL for fabrication of nanoscale periodic structures. The design of the device was based on thin-film interference, where device parameters were obtained from optimizing performance. The as-fabricated beam-flattening device demonstrated a 4-fold improvement in throughout, as compared to the conventional LIL method. The capability of fabricating large-area (2000 mm2) gratings demonstrated the scalability of our beam-flattening device. We expect our device to be readily integrable to LIL systems and applicable for a wide range of fabrication processes.