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Experimental challenges of stress measurements with resonant micro‐Raman spectroscopy
Author(s) -
Dietrich B.,
Dombrowski K. F.
Publication year - 1999
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/(sici)1097-4555(199910)30:10<893::aid-jrs468>3.0.co;2-3
Subject(s) - raman spectroscopy , microelectronics , wafer , coherent anti stokes raman spectroscopy , silicon , spectroscopy , optics , stress (linguistics) , raman scattering , materials science , laser , optoelectronics , wavelength , resolution (logic) , nanometre , physics , linguistics , philosophy , quantum mechanics , artificial intelligence , computer science
Micro‐Raman spectroscopy allows one to measure stress in crystalline materials. The method is non‐destructive and provides microscopic lateral resolution. In this paper we show that resonance excitation using an ultraviolet (UV) laser line strongly enhances the depth resolution in micro‐Raman spectroscopy. The Raman line shift becomes a true picture of the stress‐field in a 12 nm thick surface layer, whereas visible light averages over a depth of some hundreds of nanometers. We review the effects of defocusing and inhomogeneous scattering, and present results obtained from a processed wafer. Measurements of stress fields in a sample taken from a typical silicon integrated circuit process prove the strongly enhanced resolution. The UV light, therefore, allows one to resolve stress components averaged out by longer wavelength light, giving a much better way to pinpoint areas of critical stress levels that would likely lead to defects in subsequent processes in silicon microelectronic production. Copyright © 1999 John Wiley & Sons, Ltd.