Large-area submicron replica molding of porous low-k dielectric films and application to photonic crystal biosensor fabrication

We demonstrate a replica-molding method for submicron patterning of a low-index sol–gel nanoporous glass for the purpose of fabricating large-area (∼80 cm2) label-free photonic crystal optical biosensors. Scanning electron micrographs show the sol–gel exhibited minimal shrinkage and good substrate adhesion and depict precise and uniform pattern transfer over the fabricated area within the limits of measurement resolution. A unique characterization approach is described in which the photonic crystal optical resonance is used to accurately and quickly characterize the geometrical and material property uniformity over a large area. Uniformity within 1% was measured over an 80 cm2 area. We suggest that this robust method is an excellent approach for photonic crystal sensor fabrication, and may also find applications in integrated optics and electronics.