Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Scanning Electron Microscope Dimensional Metrology using a Model-based Library



John S. Villarrubia, Andras Vladar, Michael T. Postek


The semiconductor electronics industry places significant demands upon secondary electron imaging to obtain dimensional measurements that are used for process control or failure analysis. Tolerances for measurement uncertainty and repeatability are smaller than the spatial resolution of edges in the scanning electron microscope (SEM) that is used to perform the measurements. Image processing techniques, historically used to identify edge locations, are inadequate under these conditions.An alternative approach, based upon Monte Carlo electron transport modeling to assign edge positions, has been developed. The specimen shape is parameterized, and parameters are iteratively adjusted to produce the best least squares fit to the measured image. Because Monte Carlo simulators are too slow to be used directly in such an iterative calculation, the Monte Carlo technique is used relatively few times to construct a library of results for parameters spanning the process space of interest. A function that interpolates the library then becomes a surrogate that is used to rapidly compute the model function as needed. This procedure has yielded measurement results from top-down SEM images that are in good agreement with cross-section measurements and that have asmuch as a factor of 3 better same-site repeatability than themore traditional techniques. Published in 2005 by John Wiley & Sons, Ltd.
Surface and Interface Analysis


critical dimension (CD), model-based library, scanning electron microscopy (SEM), dimensional metrology, linewidth


Villarrubia, J. , Vladar, A. and Postek, M. (2005), Scanning Electron Microscope Dimensional Metrology using a Model-based Library, Surface and Interface Analysis (Accessed July 25, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created January 1, 2005, Updated February 19, 2017