The aim of this paper is to contribute to the understanding of the effects of noise on LER/LWR parameters when they are measured through the analysis of top-down CD-SEM images. To this end, first we present a methodology for the generation of synthesized CD-SEM images including resist lines with predetermined CD/pitch and LER/LWR parameters in which the noise level can be tuned at will. The sources of noise can be the shot noise of SEM electron beam (Poisson-type) and the microscope electronics (Gaussian-type). Then we use the generated CD-SEM images to evaluate three methods devised for the reduction of noise effects and the extraction of noise-free LER/LWR parameters. The first method (called fractal method) is presented for first time while the next two (model filtering and Power Spectral Density) have been already proposed and applied in literature. We compare the output of each method with the noise-less LER/LWR parameters for various noise levels, number of images and LER/LWR initial parameters and discuss their advantages and limitations.

Date Published: 10 April 2013
PDF: 10 pages
Proc. SPIE 8681, Metrology, Inspection, and Process Control for Microlithography XXVII, 86812L (10 April 2013); doi: 10.1117/12.2018245

Published in SPIE Proceedings Vol. 8681:
Metrology, Inspection, and Process Control for Microlithography XXVII
Alexander Starikov; Jason P. Cain, Editor(s)