Abstract As the feature size in integrated circuits (ICs) become smaller, the techniques we use to localize defects must also progress to the level that they can resolve potential errors. Additionally, because most errors cannot be identified by visual inspection alone, it is necessary to develop techniques, such as thermography, with the capability of localizing failures to the specific component or defect at fault. This paper will review the theory and application of an advanced subsurface (through the substrate) analytical technique for IC failure analysis – solid immersion lens thermal emission microscopy.