Fabrication of nanostructures with laser interference lithography

Maskless nanostructure fabrication by laser interference lithography (LIL) using Lloyd's mirror interferometer is investigated. With the usage of 100 nm thickness high contrast i-line positive photoresist PFI-88 A6, discrete uniform dot pattern is achieved with stable dose. The edge quality is improved by anti-reflective coating (ARC) between the substrate and the photoresist to minimize the interference of vertical standing waves. Using AZ-BARLi-II 90 (ARC), 100 nm uniform dot pattern with smooth and round edge quality is demonstrated. Three regions of laser intensity distributions and vertical standing wave schematics are described. This nanopatterning technology has potential applications in high density data storage as well as nano-device fabrication.