Electrochemical and optical processing of microstructures by scanning probe microscopy (SPM)

Two micro processing techniques based on scanning probe microscopy (SPM) are described. One is electrochemical etching and deposition using a scanning tunneling microscope (STM). STM is very useful tool of nm-scaled observation, and it can be also used as precise positioner in micro processing. In micro electrochemical processing system, a potentiostat for processing is externally attached to STM system, a STM probe was set very closely to a metal substrate in electrolyte solution, and voltage was applied between the substrate and the probe. Then electrochemical reaction occurs in restricted area of the substrate. Therefore, micrometer-size structures are produced by faradic current. A line pattern, which is 200-300 nm in width and 100 nm in depth, was electrochemically etched. When polarity of applied voltage was inverted, a bump pattern, 300 nm in diameter, 200 nm in height, was electrochemically deposited. Another processing method is using a scanning near-field optic/atomic force microscope (SNOAM). The SNOAM provides simultaneous topographic and optical images with high resolution beyond the diffraction limit, better than 100 nm. The optical processing is demonstrated in the photoresist film by the SNOAM. We obtained pit and line patterns down to 100 nm in diameter and width, respectively.