Cost-effective laser interference lithography using a 405 nm AlInGaN semiconductor laser

This paper presents a cost-effective interference lithography system that uses a 405 nm AlInGaN semiconductor laser. This method is cost-effective because the AlInGaN semiconductor laser has a long coherence length (∼20 m) and low price (e.g. only 1/3 that of the HeCd laser). This system successfully fabricated uniform nano-periodic patterns (line, dot and hole) in a photoresist (PR) over a 2 × 2 cm sample area. The PR patterns agreed well with simulations. Tall silicon nano-structures were fabricated by deep reactive ion etching (DRIE) using a PR pattern as a direct etch mask layer. Aspect ratios of 25 with smooth and vertical sidewalls were achieved after 32 DRIE cycles.