Evaluation of Mask Fidelity using automated edge placement error measurement with CD-SEM images

Mask Fidelity plays a vital role in the lithography process of cutting-edge IC fabrication. The Fidelity of Mask is fundamental to the final performance of the lithography process in production. A contour is extracted from the CD-SEM image of the corresponding fabricated mask under evaluation with at best one pixel resolution. This contour is then used to compare with the intended layout from the mask design file (GDS file). The edge placement error (EPE) between extracted CD-SEM image contour and design layout is then measured and analyzed. An accurate measurement of edge placement error with sub-pixel resolution is very crucial to evaluate the quality of the fabricated mask, therefore, the final produced pattern on wafer after the lithography process in production.