High-resolution differential thermography of integrated circuits with optical feedback laser scanning microscopy

Abstract

We demonstrate a noninvasive technique for generating differential thermal maps of semiconductor edifices in integrated circuits (IC) at diffraction-limited resolution. An inexpensive optical feedback laser-scanning microscope detects changes in the optical beam-induced currents (OBIC) that are produced in the active layer in response to variations in the IC package temperature. The OBIC yield of a semiconductor normally increases with temperature. A differential thermal map derived from the OBIC output variations, shows locations of high thermal activity in the active layer including anomalous regions where the OBIC outputs decrease with increasing temperature. Anomalous regions are loci of accumulating semiconductor electrical resistance that are highly susceptible to device failure. They provide the best jump-off points for efficient and accurate IC fault analysis procedure.