Holistic EPE measurement and qualification by large field of view (LFOV) contour-based metrology

Semiconductor scaling calls for methodologies of edge placement error (EPE) monitoring to indicate patterning defects that impact device yield more accurately. Contour-based metrology can leverage large field of view (LFOV) imaging capability to characterize local edge placement variations. Local effects contribute a large percentage of the total EPE budget and accurate characterization of these local effects is important to future EPE control. Contour-based metrology can be integrated seamlessly with inline EPE monitoring platforms, providing timely feedback for patterning performance and optimization. This work provides an overview of the large variety of data generated from contour-based metrology and studies the concept of contour-based precision as a performance metric. An assessment of contour-based metrology improvement on next generation EPE metrology systems in different scan directions is presented to quantify the impact of wafer charging on metrology error on High-NA relevant designs. The next generation system demonstrates 50% precision edge placement improvement, which can be broken down to 45% CD improvement and 30% alignment and distortion improvement due to enhanced resolution and distortion correction. The paper also introduces the usage of hybrid EPE monitor mark, a novel approach to monitoring on wafer EPE performance on device like structures, for logic EPE monitoring and control applications. The benefit of large field of view imaging to accurately characterize local effects is presented, demonstrating <0.25nm distortion residual at 8um FOV.