Failure analysis of small contamination at the surface and sub-surface interface represents a major set of common microelectronics and semiconductor issues. The application of O-PTIR spectroscopy analyses provides flexibility to sample preparation and improves sensitivity to very small levels of contamination even below <1 micron in layers or particles on or just below the surface. The detection of this contamination can be limited if only bright field imaging is used to contrast the region of interest (ROI) and the surrounding structure. Adding fluorescence microscopy is an additional imaging technique that adds another layer of chemical specificity and provides locations of unseen ROI’s for additional IR and Raman spectral analysis.

Optical microscopy techniques used by forensic analysts are shown to have application to failure analysis problems. Proper set up of the optical microscope is reviewed, including the correct use of the field diaphragm and the aperture diaphragm. Polarized light microscopy, bright and dark field methods, refractive index liquids, and a particle reference atlas are used to identify contamination found on semiconductor products.