Nanoprobes for near-field optical microscopy manufactured by substitute-sheath etching and hollow cathode sputtering

This article reports a new approach for probe manufacturing, which is the key component in scanning near-field optical microscope (SNOM). The wet-etching process, to create the tip at the apex of a tapered fiber, has been optimized. Typical tip features are short tapers, large cone angles (30°), and very small diameters (<50nm). Next process steps are performed in an original arrangement of plasma device, based on a modified hollow cathode discharge. It is used for both, to remove the dust particles or the etching residues from the tip surface and to coat the tapered region with a metallic ultrathin and compact film. To complete the probe’s fabrication, the tips are opened by dry electrolytic erosion. These probes have been successfully tested for SNOM applications.