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5 June 2001 Analytical first-order model of light scattering from submicron pyramidal pits
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Proceedings Volume 4275, Metrology-based Control for Micro-Manufacturing; (2001)
Event: Photonics West 2001 - LASE, 2001, San Jose, CA, United States
Silicon wafers that are fabricated by the Czochralski technique contain pyramidal pits, which are referred to in more general terms as crystal-originated particles (COPs). Because wafer inspection systems now benefit from the predictability of scattering from particles of known size, shape, and composition, it is of interest to achieve the same level of predictability for surface breaking defects such as pits. A model, valid for s-polarization and a high incidence angle, is based on the Fraunhoffer approximation for the diffraction from a square aperture, which neglects edge effects due to surface current accumulation at the periphery. Measurements and the model show that (using the prescribed optics configuration) a characteristic peak occurs between 20 and 45 degrees in the forward scatter region that increases in magnitude and moves forward with increasing pit size. Wafer inspection system designers can use this kind of information to improve their instruments' ability to distinguish between surface contaminants and COPs and to correctly gauge the size of COPs. Further work is underway to improve the fit between the model and the data and to extend its range of applicability.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Michael Jordan Jr., Rodolfo E. Diaz, and E. Dan Hirleman "Analytical first-order model of light scattering from submicron pyramidal pits", Proc. SPIE 4275, Metrology-based Control for Micro-Manufacturing, (5 June 2001);

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