Three-dimensional patterning of nanostructures using atomic force microscopes

The recent advances of the fabrication technology using atomic force microscopes (AFMs) are reviewed with the focus on its effectiveness and flexibility in patterning three-dimensional (3D) engineering nanostructures. The specific hardware and software requirements, including manipulability, precision, and automation, for enhancing the capability, reliability and repeatability in patterning 3D nanostructures are evaluated. The recent progresses on patterning the one- and two-dimensional nanostructures, which provide the basic building blocks, are first assessed. The truly 3D nanostructures, which were fabricated by two general approaches, layer manufacturing and continuous depth (or height) variation, are then presented to illustrate the efficiency and versatility of the specific patterning technique adopted. The geometric precision and reliability of the features created as well as the patterning principle involved are also studied. Finally, for improving the productivity in patterning 3D structures, the schemes using parallel processing, speed increasing, and larger tips, are elaborated with a recommendation on the areas for future efforts in developing better AFM patterning techniques.