Spectroscopic interference microscopy technique for measurement of layer parameters

A novel method is proposed for the measurement of layer parameters using spectroscopic double-beam interference microscopy. The contribution of each partial wave reflected from the layer interfaces to the interferogram is treated separately and the total interferogram is obtained as their coherent sum. When an annulus aperture is used, an analytic expression is derived for the interferogram that allows fast direct comparison between measured and calculated spectra from which refractive indices and thickness of layers can be determined simultaneously. Subnanometre accuracy of the film thickness measurement is shown to be possible.