Observation of micro-characters using three-dimensional shape measurement method based on speckle interferometry

Speckle interferometry has long been used to measure the deformation of an object with a rough surface. Currently, it can be used to measure the shape of a three-dimensional microstructure by intentionally applying a lateral shift to the measured object and analysing the change in phase due to the shift. Furthermore, the validity of this measurement method has been verified in terms of the measurement of microstructures, such as micro-silica spheres and diffraction gratings. In this study, the validity of the measurement of an object possessing an artificial shape by this method in the micro-region is analysed using micro-characters drawn by an electron-beam lithography system. It is confirmed that this method can perform the shape measurement of three-dimensional microstructures that are artificially produced. This was achieved by observing the letter 'U', illustrated with a line width beyond the diffraction limit of the objective lens.