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|Author(s):||Nien F. Zhang; Michael T. Postek; Robert D. Larrabee;|
|Title:||Statistical Measure for the Sharpness of the SEM Image|
|Published:||July 01, 1997|
|Abstract:||Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. Testing and proving that the instrument is performing at a satisfactory level of sharpness is an important aspect of quality control. The application of Fourier analysis techniques to the analysis of SEM images is a useful methodology for sharpness measurement. In this paper, a statistical measure known as the multivariate kurtosis, is proposed as a useful measure of the sharpness of SEM images. Kurtosis is designed to be a measure of the degree of departure of a probability distribution from the Gaussian distribution. It is a function of both the fourth and the second moments of a probability distribution. For selected SEM images, the two-dimensional spatial Fourier transforms were computed. Then the bivariate kurtosis of this Fourier transform was calculated as though it were a probability distribution, and that kurtosis evaluated as a characterization tool. Kurtosis has the distinct advantage that it is a parametric (i.e., a dimensionless) measure and is sensitive to the presence of the high spatial frequencies necessary for acceptable levels of sharpness. The applications of this method to SEM metrology will be discussed.|
|Conference:||Scanning Probe Metrology III|
|Proceedings:||Proceedings of SPIE,Metrology, Inspection, and Process Control for Microlithography XI, Susan K. Jones, Editor|
|Pages:||pp. 375 - 387|
|Location:||Santa Clara, CA|
|Dates:||March 10, 1997|
|Keywords:||Fourier transform,image analysis,kurtosis,metrology,scanning electron microscope,sharpness|
|Research Areas:||Manufacturing, Metrology|