Application of a mercury cadmium telluride focal plane array to semiconductor device manufacturing and reliability.

A mercury cadmium telluride (MCT) focal plane array has been used to build a combined visible light and infrared photoemission microscope with sensitivity up to 500 times better than conventional PEMs, which are based on either intensified or cooled CCDs. PEMs are widely used for integrated circuit failure analysis and in yield enhancement programs; they detect and identify failure sites by the low levels of light emitted from the semiconductor. An MCT based PEM operating in the wavelength range 800 nm to 2500 nm offers several advantages over systems operating in the visible part of the spectrum. Beyond 1000 nm, band gap emission is imaged directly from forward biased p-n junctions and this part of the spectrum includes the regions of most intense emission from avalanche breakdown and hot carrier defects. Beyond 1000 nm most silicon is effectively transparent and this offers significant advantages for backside failure analysis, especially for flip chip devices. Thermal emission is detected from areas approximately 1 degrees C above ambient so failure mechanisms not usually amenable to analysis by PEM can be located.