IC failure analysis using the laser scanning microscope

The laser scanning microscope (LSM) is a fairly new device for contactless testing. The nondestructive nature of the laserbeam and a minimum of preparation favorizes its use as an analytical tool. Beside the scanning mode which is useful for material study the laser beam can be positioned in spot mode with a high spatial resolution and a fine focused beam on the probe surface. We introduce some measurement methods based on optical beam induced currents inside the semiconductor and on electrooptical effect in external media. These methods are extremely useful for CMOS circuit failure analysis leading to a complete functionality check. Logic state detection in digital CMOS circuits and signal acquisition from a node inside the circuit are internal probing techniques. To locate and analyze latch-up in CMOS ICs we have developed a fully automated latch-up analyzer coupled with the CAD system