FILM THICKNESS DETERMINATION BY MATLAB ASSISTED ELLIPSOMETRY

Abstract

Film thickness determination is important in lithography as the thickness of thin

semiconductor or metal layer is critical in device fabrication. Ellipsometry, which is a nondestructive optical technique, recently has been used for characterizing the

refractive indices and thickness of thin films and interfaces. It deals with the measurement of the changes in the polarization state of light upon reflection from a surface via two angles Ψ and Δ. In this work we developed a MATLAB subroutine to work seamlessly with the measured values of Ψ and Δ. to estimate film thickness

numerically. A simulation model of single film on substrate was constructed and fitted with the measured data for the thickness estimation. The sum of squared error between the model and measured data, was use to evaluate the fitting. Results obtained were reliable as the thicknesses reported were calculated using values of Ψ and Δ from multiple angles. On the whole, we have successfully determined thickness for various films with our developed MATLAB subroutine.