Fabrication of metal nano-wires by laser interference lithography using a tri-layer resist process

This article presents a general method for fabrication of large-area metal nano-wires using laser interference lithography and a lift-off process. A tri-layer resist structure consisting of a thin top photoresist, a metal inter-layer and a thick bottom photoresist is introduced to fabricate thick photoresist nano-patterns. Laser interference lithography is used to pattern the top thin photoresist and the lift-off process is applied to acquire nano-patterns with high duty cycle. Thick photoresist nano-patterns with high duty cycle are fabricated by the reactive ion etching process. Using the thick photoresist nano-patterns, metal nano-wires with a 100 nm square cross-section are successfully fabricated by a lift-off process. The method presented in this article can produce large-area metal nano-wires with high-throughput and low cost, as compared with the traditional method using electron beam lithography. Moreover, laser interface lithography is a maskless lithography method and can fabricate nano-patterns with high uniformity and good period controllability, which makes this method a promising way to manufacture metal nano-wires devices.