DEI as a performance and defect analysis tool - dynamic electroluminescence imaging (DEI) from both sides of an EPROM memory device

Dynamic electroluminescence imaging (DEI) represents an important non-invasive technique for the investigation of performance and defect analysis of CMOS microelectronic circuits. Luminescence transients that accompany the switching of transistors in operating devices can be measured and timing diagrams produced without contacting internal circuitry. Moreover, measurements can be made either from the processed side of a device or through the substrate at the backside, thus enabling information to be collected from circuits that are shielded from above by multiple metallization layers. We report measurements made on both sides of a 512 K-bit EPROM. The results demonstrate the ease with which timing information with better than 120 ps resolution can be obtained from either side of a device.