Title:
Practical Laser Interference Lithography

Abstract:
Laser Interference Lithography (LIL) is a powerful maskless patterning technique that exploits the interference of two or more coherent beams to create high-resolution sub-µm periodic structures over large areas.

However, even though setting up a simple benchtop Lloyd's mirror LIL experiment seems straightforward, developing a robust, versatile, and reliable LIL process comes with several subtle challenges that may elude first-time builders.

In this talk, I share our journey in designing, building, and commissioning a custom raster-scanning two-beam UV LIL system, from our first naive lab experiments up to the fully enclosed safety-interlocked system installed in the shared INL cleanroom. I present the basics of interference lithography and walk you through the design choices and evolution of our optical setup, illustrating multiple pitfalls and honest mistakes (so many) we learned to correct along the way. I share practical tips to select components to meet the specifications, and how to set up optomechanical assemblies that greatly facilitate the optical alignment when reconfiguring the system for new patterning resolution or field size. Throughout the talk, I present several partially-failed and partially-successful experimental patterning results, not only to showcase the current commissioning status of our LIL system, but also to give concrete trial-and-error examples and lessons learned that can help you save time and avoid repeating our errors in your own interference lithography experiments.