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Optical scatterometry for process metrology

The intensity of radiation diffracted from periodic structures is extremely sensitive to slight variations in the geometry and composition of the diffracting structure. Rigorous diffraction theory provides a mechanism for accurate analysis of the scattered waves. Scatterometry is a metrology technique that combines the sensitivity of diffraction from periodic structures with a first principle solution of electromagnetic wave diffraction from these structures. The technique is self-calibrating, and sub-nm static and dynamic precision has been demonstrated for the measurement of sub-0.25 μm structures. We provide an overview of the development of this metrology technique, along with the theoretical foundation of rigorous diffraction analysis and its application to the analysis of the scattered data measured by the scatterometer.