In-situ and high-resolution optical observation in local anodic oxidation process using a scanning near-field optical microscope.

Using a local oxidation process with a probe tip of a scanning near-field optical microscope (SNOM), antimony oxide structures with a pattern width of several 100 nm were fabricated on antimony thin films. We also investigated the characteristics of the oxidation process using the transmission mode SNOM. Although slight topographic changes due to oxidation were observed by atomic force microscopy, an increase in transmission due to the phase change of the metal to transparent oxide was observed. The depth of the oxide embedded in the antimony film was estimated from the change of the transmission intensity without destroying the sample. This fabrication method is appropriate for making a prototype of future nano-optical devices and for trimming them in order to optimize their functions on demand.