Metrology and Analysis of Two Dimensional SEM Patterns

摘要

A variety of techniques to characterize the lithographic quality of top-down two-dimensional patterns are described. Beginning with a top-down SEM micrograph, image processing and feature edge detection are used to extract a polygon representation of the printed pattern. Analysis on the polygon yield metrics such as corner rounding radius, feature area, and line edge roughness. Comparison of two shapes (for example, actual compared to desired, mask compared to wafer, or before etch compared to after etch) produces metrics such as overlapping area and the critical shape difference. Numerous examples of the utility of this approach will be given for SEM images of masks and wafers. The result is a set of numeric metrics of two-dimensional pattern fidelity applicable to lithographic evaluation, improvement and control.