Advanced confocal technique for submicron CD measurements

Abstract

A new CD measuring tool is described, Carl Zeiss Axioscan, which is based on confocal scanning technology. The advantages of having a great variability in choosing the illumination is demonstrated with several examples. Selection of deep UV illumination increases the lateral and height resolution of the system. Matching the illumination to the optical constants of the materials to be measured enhances the reproducibility and the accuracy of the measurement.In the description of the system,it is shown how the confocal scanning technique can be implemented with conventional light sources, and how this increases the flexibility in illumination conditions.