Spatially resolved stress analysis using Raman spectroscopy

Raman spectroscopy using a laser microprobe (also called micro-Raman) is be coming more widely used to study stress distribution in solids, particularl y in micro-electronic device structures, because of its potential for high spatial resolution. Typically the diameter of the focused laser beam is 1 m u m but the penetration depth can vary from tens of nanometres to several m illimetres and thus samples a potentially large volume of the strained stru cture. Each point within this volume scatters light with a Raman wavenumber characteristic of the local stress at that point, Because the beam is usua lly focused, the distribution of light intensity in this volume and the int erpretation of the resulting spectrum, is complicated. Recently we have dev eloped a method to calculate theoretically the Raman spectra from such stru ctures using stress fields calculated by Finite Element Modeling, The metho d is summarised here and illustrated with application to two examples; a Si Ge quantum wire stripe on silicon and a nitride stripe on silicon. The erro rs incurred by using simpler data analysis methods are discussed and found to be significant. Copyright (C) 1999 John Wiley & Sons, Ltd.