A new method to determine the optical constant and thickness of thin films is proposed. Based on the Fresnel’s optical expression, the improved flexible tolerance method(FTM) is employed in the case of a digital mode...A new method to determine the optical constant and thickness of thin films is proposed. Based on the Fresnel’s optical expression, the improved flexible tolerance method(FTM) is employed in the case of a digital model of thin film to fit the curve of measured reflectance spectrum. The simulation results show a satisfactory correlation of the optical constant with the thickness of the target film. By taking the influence of nonlinear condition into account as well as more direct and indirect limitation, the precision and value-searching efficiency have been improved. Furthermore, the problem of dimension degradation, which exists in “Downhill Simplex”, has been successfully avoided. No initial input is needed for the procedure of optimization to achieve optical solution, which makes the whole processing of value calculation much more convenient and efficient.展开更多
文摘A new method to determine the optical constant and thickness of thin films is proposed. Based on the Fresnel’s optical expression, the improved flexible tolerance method(FTM) is employed in the case of a digital model of thin film to fit the curve of measured reflectance spectrum. The simulation results show a satisfactory correlation of the optical constant with the thickness of the target film. By taking the influence of nonlinear condition into account as well as more direct and indirect limitation, the precision and value-searching efficiency have been improved. Furthermore, the problem of dimension degradation, which exists in “Downhill Simplex”, has been successfully avoided. No initial input is needed for the procedure of optimization to achieve optical solution, which makes the whole processing of value calculation much more convenient and efficient.
