Fabrication of 3D metal dot arrays by geometrically structured dynamic shadowing lithography

Sphere lithography (SL), sometimes erroneously generalized as nanosphere lithography (NSL), stands out as a versatile technique capable of producing 2D periodic micro- and nanostructures with general materials applicability, flexible size and shape control, high throughput, and elegance of simplicity. Many of the fundamental aspects of the features produced by SL have been investigated in a systematic manner, including the optical, magnetic, electronic, and catalytic behaviors with emphasis toward applications in biosensing, ultrasensitive spectroscopy, and nanodevice fabrication. Previous work has primarily focused on two-dimensional patterning, however, with little attention paid to vertical growth of the SL features. In this work, the 3D structural evolution of metal dot arrays at two different length scales was demonstrated by SL-based geometrically structured dynamic shadowing lithography (GSDSL). An empirically derived model of structural growth is also developed to predict the shape and size of the features in this system.