A prototype scanning tunneling microscope (STM) was developed to apply the STM technology for practical micro surface observation. The features of the instrument are : (1) A 3-dimensional piezo inchworm mechanism to approach and select observation area, (2) a conversion technology of tunneling current fractuation to gap fractuation and (3) an automatic approach system of electrochemically etched probe tip to tunneling effect region. Various STM images were obtained both with atomic scale and μm scale. Among them are (7 × 7) reconstructed Si (111) surface, groove shape of soft X-ray gratings and groove shape of an optical disc, which were compared with SEM and TEM images. The STM is found to be practical to evaluate an extremely fine surface structure formed with recent ultra precision technology.
