Fabrication of super-sharp nanowire atomic force microscope probes using a field emission induced growth technique

A relatively simple and consistent technique based on field emission induced growth has been developed to grow a single metallic nanowire on an atomic force microscope (AFM) tip. A clamping setup with two micromanipulators ensures that the fabrication of a vertically aligned nanowire probe, which is sharp, robust, and with high aspect ratio, can be achieved on different types of AFM cantilevers with different force constants. The controlled growth technique has been used to produce tungsten nanowire AFM probes with great consistency and high reproducibility. The tungsten nanowires were grown to lengths between 100 nm to 1.5 μm with radius of curvature at the tip end typically between 1–2 nm. Experiments using the fabricated tungsten nanowire AFM probe demonstrate its ability to produce high-resolution AFM images and improved profiling of structures with steep sidewalls due to its very sharp tip and high aspect ratio. The technique can be extended to fabricating other types of metallic nanowire AFM probes or even composite nanowire AFM probes by using different precursor gases. Experiments have been successful in fabricating cobalt nanowire AFM probes which are able to produce good high-resolution AFM images as well.