Fabrication of large-area periodic nanostructures using two-mirror laser interference lithography

This study demonstrates laser interference lithography (LIL) using two rotatable mirrors located at a height of 20–50 cm in order for reflected coherent beams with a controlled incident angle to interfere on a substrate placed horizontally. The periods of the nanostructures are adjusted by the height of the mirrors from the substrate and the distance between the two mirrors without any significant change of the optical alignment. The periodic nanostructures are fabricated on a 6 inch Si substrate using the horizontal substrate LIL setup incorporated with an X-Y translation stage. For large area nano-patterning, a multi-step process is employed which repeats exposure- and-translation to expose small areas one by one.