The infrared photoemission microscope as a tool for semiconductor device failure analysis

An infrared photoemission microscope (IRPEM) based on a cadmium mercury telluride (CMT) focal plane array, developed originally for astronomical applications and covering the wavelength range 800 to 2500 nm, has been used to characterise emission phenomena in several semiconductor devices. Using the p-n junction of a simple transistor it was found that in forward bias three emission mechanisms operate. As well as the expected band gap emission, localised emission was wavelengths. There was also corresponding to a temperature rise of 2-3/spl deg/C. In reverse bias, emission was localised to one or more sites depending on the current. The ability of the system to detect emission from the backside of an un-thinned integrated circuit was demonstrated using a subscriber line interface circuit (SLIC) and BiCMOS buffer.