Nanofabrication with proximal probes

In this paper, we describe the use of proximal probes, such as the atomic force microscope (AFM) and the scanning tunneling microscope (STM), for nanofabrication. A resistless proximal probe-based lithographic technique has been developed that uses the local electric field of an STM or conductive AFM tip that is operated in air to selectively oxidize regions of a sample surface. The resulting oxide, typically 1-10 nm thick, can be used either as a mask for selective etching or to directly modify device properties by patterning insulating oxides on thin conducting layers. In addition to this resistless approach, we also describe the use of the STM/AFM to modify the chemical functionality of self-assembling monolayer films. Such modified films are used as a template for the selective electroless plating of metal films. The above processes are fast simple to perform, and well suited for device fabrication. We apply the anodic oxidation process to the fabrication of both semiconductor and metal-oxide devices. In these latter structures, sub-10 nm-sized device features are easily achieved, and we describe the fabrication of the smallest possible device, a single, atomic-sized metallic point contact by using in situ-controlled AFM oxidation.