Multicolor, visible-light nanolithography

摘要

Traditional approaches to improving photolithographic resolution rely on using shorter and shorter wavelengths of electromagnetic radiation. This approach faces ever greater challenges each time the operating wavelength is decreased. Recently, alternative approaches to nanoscale photolithography have been introduced that employ photoresists that are sensitive to multiple colors of visible light. One or more colors of light activate the photoresist, and one or more colors of light can subsequently deactivate it. By controlling the spatial patterns of the colors, it is possible to create features with sizes that are far below the diffraction limit. This approach has been demonstrated for laboratory-based fabrication using multiphoton-absorption-based fabrication, but with improvements in materials it shows great promise for semiconductor lithography as well. A number of approaches to two-color photolithography have been demonstrated. A next generation of schemes that involve a third color of light has the potential to improve the performance of multicolor lithography substantially. The basic premises of both two-color and three-color lithography are discussed, and experimental examples of each type of approach are presented.