Precision interferometric surface metrology of transparent thin film using wavelength tuning

Indium tin oxide (ITO) thin films are the important component in display and semiconductor industries because of their excellent electrical and optical properties. To improve the reliability and performance of these films, the surface shape and thickness should be measured accurately. In this research, the surface topography of an ITO thin film on the surface of a supporting plate was measured by wavelength tuned phase shifting interferometer and polynomial window function. The surface topography is measured by compensating for the phase difference error caused by interference of the transparent thin film. Optical interference is formulated by the phase and amplitudes determined by wavelength tuning and polynomial window function. The measurement method allows for noncontact (nondestructive), large aperture, and nanoscale measurement of highly reflective thin films.