A novel method to reduce the period limitation in laser interference lithography

Abstract

This article presents a novel method to apply on reducing the period limitation in laser interference lithography (LIL) by preparing a kind of nanowire arrays with the period \({\uplambda }/(4\hbox {n}\times \hbox {sin}{\uptheta }\)) instead of \({\uplambda }/(2\hbox {n}\times \hbox {sin}{\uptheta }\)). Nanowire arrays with periods of 150 and 125 nm on Si (100) substrate were fabricated successfully with a 325 nm He–Cd continuous wave laser as a light source, based on the combined process of dry etching and wet etching. It is the slight over-etching in the dry etching process and keeping the fluorine carbon organic polymer layer intact during whole process of wet etching that guaranteed the nanowire generated from the platform between two adjacent etched facets. The width of the nanowire as narrow as 50 nm was fabricated by this method, which is much more interesting for the research on the small size effect. This method is proved to circumvent the period formula limitation of the traditional LIL and makes the preparation of nanostructures with much smaller size more feasible.