Robust semiconductor overlay metrology with non-uniform illumination beams using digital holographic microscopy

Publication date
DOI http://dx.doi.org/10.1117/12.2673583
Reference M. Adhikary, T. Cromwijk, S. Witte, J.F. de Boer and A.J. den Boef: Robust semiconductor overlay metrology with non-uniform illumination beams using digital holographic microscopy In: Proc. SPIE 12618, Optical Measurement Systems for Industrial Inspection XIII, SPIE-Intl Soc Optical Eng, 2023. - pp. 126180W: 1-6
Groups Computational Imaging, EUV Generation & Imaging

Precise, accurate, and fast characterization of overlay between two layers of semiconductors during chip fabrication is an important monitoring and feedback step. Overlay, which is to be measured within the accuracy of a nanometer, is susceptible to many small imperfections in the measurement system. A digital holographic microscope measures the complex field of overlay targets using simple optics followed by computational algorithms for overlay metrology. We improved the precision of overlay measurement by correcting the inhomogeneities and asymmetries caused by the illumination spots, presenting a robust method resulting from simple calibration steps.