PLASMON-ASSISTED NANOLITHOGRAPHY EXPOSED BY FEMTOSECOND LASER BEAM THROUGH GOLD NANOSTRUCTURED PHOTOMASKS

摘要

State of the art lithography such as ArF immersion andEUV (Extreme Ultra-Violet) lithography systems haveattained a 32 nm node and has been already employedin the development of electronic devices. However, thelithography systems are not appropriate for makingnanopatterns on a positive photoresist film, such asrectangular cuboids, triangular prisms, chains, andnanogaps. These nanostructures are utilized for variousapplications such as plasmonic solar cells and photoniccrystal lasers. Here, we describe a new plasmonassistednanolithography system that is used forfabricating nano-patterns with a nanometer precision.The most attractive merit of this system is to form deepnano-patterns on a positive photoresist film. Theformed nano-patterns are completely reflected on thephotomask's design. The key technology is using twophoton-induced reaction of a positive photoresistpromoted not only by plasmonic near-field light butalso by propagating light in a photoresist film. Thispropagating light is a radiation mode from a multipolelocalized surface plasmon resonances scattered by goldnanostructures. The system does not induce nanopatterndeformation in the case of mask release. Thissystem presents a simple alternative for producingnano-patterns instead of nanoimprinting technology.