AFM-based fabrication of free-standing Si nanostructures

AFM-generated surface modifications are used to fabricate free-standing Si nanostructures. We employ the local electric field of a metal-coated AFM tip which is operated in air to selectively oxidize regions of a H-passivated Si surface. The resulting oxide, similar to 1-2 nm thick, is used as a mask for deep selective etches of the unoxidized regions of Si. The etched structures reside on a buried oxide layer which is removed to produce free-standing Si wires and cantilevers. Due to the uniformity of the exposure and self-limiting etch processes, these structures are extremely uniform, which is a critical feature for nanometer-scale device applications.