Volumetric thin film thickness measurement using spectroscopic imaging reflectometer and compensation of reflectance modeling error

In this paper, volumetric thin film thickness is measured using the spectroscopic imaging reflectometer, which consists of a microscopy optic system, variable bandpass filter and CCD camera. The volumetric thickness profile can be measured by using each pixel of the CCD camera as a spectrum sensor. The causes of reflectance modeling errors are explained, and equations for compensation are proposed. For the verification of system performance and proposed equations, the thickness of silicon oxide thin film is measured. Ellipsometer and AFM measurement results are used as nominal thicknesses for comparisons with the result of spectroscopic imaging reflectometer. From the comparisons, it is verified that the proposed equations can improve accuracy of measurement. It can be said that the proposed equations can properly compensate the error due to Gaussian distribution of filtering and lens NA.