Abstract

Based on Fresnel diffraction from phase steps, we present an optical method for real-time monitoring and measurement of thickness during the wet etching of transparent materials. It is shown experimentally that during the etching process, the visibility of diffraction fringes varies periodically with time (thickness) and the rate the etching is measured. Using dilute etching solutions, we measured an average etching rate of $5.3\mathrm{nm}/\mathrm{s}$ for glass.

© 2015 Optical Society of America

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