2024-11-28
Enhancing diffraction-based overlay metrology capabilities in digital holographic microscopy using model-based signal separation
Publication
Publication
J. Micro/Nanopattern. Mater. Metrol. , Volume 23 - Issue 4 p. 044006: 1- 14
Background: The continuous shrink of device dimensions in the semiconductor industry drives the need to improve optical microscopy techniques that are often used in overlay metrology. Achieving sub-nanometer overlay metrology precision requires near-perfect imaging conditions and an almost complete suppression of imaging artifact. Aim: Digital holographic microscopy (DHM) has been presented as a promising new overlay tool measuring the full complex-valued field, giving one computational access to the pupil plane. The unique characteristics of a holographic imaging system in combination with prior knowledge of the object under study show the capability to advance semiconductor metrology. This technique enables a further reduction in metrology target size while also offering opportunities to improve precision. Approach: We present experimental results on a model-based signal separation technique using digital pupil filtering for two different metrology challenges and demonstrate strong suppression of nuisance signals without resolution loss. Results: We will present two experimental examples of different types of pupil filtering in DHM allowing for larger region-of-interest selection to improve the diffraction-based overlay metrology precision and accuracy. Conclusion: We experimentally demonstrate that model-based signal separation in the pupil plane can significantly enhance the overlay metrology capabilities in cases where prior knowledge of the sample is present.
Additional Metadata | |
---|---|
SPIE-Intl Soc Optical Eng | |
ASML, ARCNL, VU, UvA, RUG, NWO | |
doi.org/10.1117/1.jmm.23.4.044006 | |
J. Micro/Nanopattern. Mater. Metrol. | |
Organisation | EUV Generation & Imaging |
van Gardingen-Cromwijk, T., Mathijssen, S., Noordam, M., Witte, S., de Boer, J., & den Boef, A. (2024). Enhancing diffraction-based overlay metrology capabilities in digital holographic microscopy using model-based signal separation. J. Micro/Nanopattern. Mater. Metrol., 23(4), 044006: 1–14. doi:10.1117/1.jmm.23.4.044006 |