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Blind Estimation of Tip Geometry from Noisy Images



John S. Villarrubia


Broadening of image features due to non-vanishing tip size is a well-known imaging artifact in scanned probe microscopy (SPM) topographs. This need not be a serious limitation for some types of metrology (e.g. pitch or height), but it is significant for others, particularly for width measurements of steep-sided features such as are frequently encountered on lithographically patterned wafers or for surface microroughness measurements in which the smallest wavelengths are shorter than the tip radius. If the tip shape is known, some (but not always all) of the true surface can be reconstructed to provide more reliable width and surface roughness measurements. This document is a summary abstract of a talk presented at the Third Workshop on Industrial Applications of Scanned Probe Microscopy. Two methods for estimation of tip geometry, known respectively as envelope reconstruction and blind reconstruction, are discussed. The latter method potentially has significant advantages, but suffers from implementation problems when applied to noisy images. A modification to the original algorithm produces better results when applied to such images. Tip reconstructions with and without the modification are compared.
NIST Interagency/Internal Report (NISTIR) - 5752
Report Number


AFM, atomic force microscopy, blind reconstruction, dimensional metrology, envelope reconstruction, mathematical morphology, scanned probe microscopy, scanning tunneling microscopy, SPM, STM, surface reconstruction, tip artifacts, tip estimation


Villarrubia, J. (1995), Blind Estimation of Tip Geometry from Noisy Images, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD (Accessed April 18, 2024)
Created November 2, 1995, Updated February 19, 2017