Integration of tunable two-dimensional nanostructures on a chip by an improved nanosphere lithography method

By uniform infiltration of a different material into monolayered polystyrene colloidal crystals and by flexibly combining the two materials as etching masks, we demonstrate an improved nanosphere lithography method that possesses the ability to produce a diverse range of tunable nano-patterns in a small area with good reproducibility. The factors that affect the infiltration height and uniformity are characterized and discussed. Annular gap arrays, close-packed ring arrays, and bowl arrays are demonstrated by this method. The geometry size of these nano-patterns can be tuned over the range 10 nm to ∼500 nm with steps of ∼5 nm during the fabrication progress. Formation mechanisms of the close-packed ring arrays are experimentally investigated. Because all the fabrication processes involved in this method are adaptable to sophisticated integrated circuit fabrication techniques, most of the nano-patterns produced by this method could be integrated on thin films, which is desirable for optics integration and array sensing.