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Proceedings Paper

Specular spectral profilometry on metal layers
Author(s): Junwei Bao; Xinhui Niu; Nickhil H. Jakatdar; Costas J. Spanos; Joseph J. Bendik
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Paper Abstract

With the advent of deep sub-micron semiconductor technology, metrology for metal interconnects becomes more critical. In addition to the line width, information about the height and the sidewall profile is needed to ensure good circuit performance. Conventional metrology tools such as CD SEMs and AFMs are either unable to measure the profile, or too slow for production process control. Scatterometry is a promising candidate as in situ, full-profile metrology tool. In this method, scattering of broadband light (240 nm to 760 nm) on periodical structures is simulated by approximating the structure with a finite series of Fourier expansion terms. By comparing the measured spectrum and the simulated spectra for various possible profiles in a precalculated library, the profile can be extracted. Previous work has shown good results on resist structures. For metal structures, however, more diffraction orders need to be included to accurately simulate light scattering. In this study, a library for 0.22 micrometer line and 0.44 micrometer space metal grating structures is generated using 31 orders. The profiles of metal grating structures of the same size are extracted using this library. Our data shows that the correlation between CD-SEM and scatterometry-based profile extraction appears to be related to the sidewall angle of the profile. These discrepancies will be analyzed and discussed.

Paper Details

Date Published: 2 June 2000
PDF: 11 pages
Proc. SPIE 3998, Metrology, Inspection, and Process Control for Microlithography XIV, (2 June 2000); doi: 10.1117/12.386454
Show Author Affiliations
Junwei Bao, Univ. of California/Berkeley (United States)
Xinhui Niu, Timbre Technology, Inc. (United States)
Nickhil H. Jakatdar, Univ. of California/Berkeley (United States)
Costas J. Spanos, Univ. of California/Berkeley (United States)
Joseph J. Bendik, Consultant (United States)

Published in SPIE Proceedings Vol. 3998:
Metrology, Inspection, and Process Control for Microlithography XIV
Neal T. Sullivan, Editor(s)

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