Spatially resolved stress analysis using Raman spectroscopy

✍ Scribed by A. Atkinson; S. C. Jain

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 109 KB
• Volume: 30
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/(sici)1097-4555(199910)30:10<885::aid-jrs485>3.0.co;2-5

✦ Synopsis

Raman spectroscopy using a laser microprobe (also called micro-Raman) is becoming more widely used to study stress distribution in solids, particularly in micro-electronic device structures, because of its potential for high spatial resolution. Typically the diameter of the focused laser beam is 1 µm but the penetration depth can vary from tens of nanometres to several millimetres and thus samples a potentially large volume of the strained structure. Each point within this volume scatters light with a Raman wavenumber characteristic of the local stress at that point. Because the beam is usually focused, the distribution of light intensity in this volume and the interpretation of the resulting spectrum, is complicated. Recently we have developed a method to calculate theoretically the Raman spectra from such structures using stress fields calculated by Finite Element Modelling. The method is summarised here and illustrated with application to two examples; a SiGe quantum wire stripe on silicon and a nitride stripe on silicon. The errors incurred by using simpler data analysis methods are discussed and found to be significant.