Laser Micro/Nano Processing of Materials Based on Light Absorption of Metallic Nanoparticles

Abstract

Novel laser processing methodology has been developed toward a breakthrough in the diffraction limit. It is triggered by plasmonic resonant excitation of metallic nanoparticles. The methodology falls into two categories. One is based on the enhancement effect of electromagnetic fields of incident light by localized surface plasmon. The effect can induce laser processing with a great efficiency and even 2-photon absorption. Spatial resolution less than 10 nm was demonstrated by Ueno and Misawa using a “gap-mode plasmon” in a gold nano-dimer. Obara’s group also showed a method of efficient Si processing using an isolated gold nanoparticle. The other method is based on photothermal temperature elevation of a metallic nanoparticle following electron-lattice relaxation in the metal. The fundamental mechanism of the processing is superheating of Au nanoparticles by resonant excitation, with subsequent explosive vaporization to leave nanoholes of a target polymer film. Characteristics and mechanisms of these methods are reviewed.