Chromatic monitoring technique for thickness measurement of thin transparent films

摘要

The main topic of this work is the development and optimisation of a new measurement method used for in-situ thickness monitoring of thin films grown using plasma. Because of their inherent limitations, measurement methods described in literature cannot be used during the low-temperature plasma processes as they are sensitive to optical noise generated by plasma and the substrate heater. To address this problem, a new method, based on chromatic sensing, has been developed. The monitored film is illuminated by polychromatic light which interferes in it, is reflected from it and collected by three detectors with spectral responsivities coincided with human eye. Based on signals from these detectors and known relationship between the spectrum of the reflected light and the thickness of the film, it is possible to monitor the thickness of the film in real time.