Angle-resolved reflectometer for thickness measurement of multi-layered thin-film structures

摘要

The principle of angle-resolved reflectometry is exploited for thin-film thickness measurements. Within an optical microscope equipped with a high NA objective, a sequence of quasi-monochromatic light of different wavelengths is generated from a white-light source through spectral filters. Then for each wavelength, the reflectance intensity from the thin-film sample is monitored on the back focal plane of the objective. This enables collection of reflectance with varying incident angles. The film thickness is then uniquely determined by fitting the measured data to an ideal multi-reflection model of thin films. This method can be readily extended to multi-layered film structures, finding applications for industrial inspection of semiconductor devices and flat panel display products.