A CAD coupled laser beam test system for digital circuit failure analysis

A nondestructive automated digital test system is described. It consists of a laser scanning microscope (LSM) coupled to a CAD (computer-aided design) layout database. Logic state detection and automated failure analysis in CMOS circuits can be done without the need of vacuum and with a minimum of circuit environment preparation. The coupling of the LSM and the CAD layout database leads to automated node location and shortens the failure search because it enables the user to backtrace signal interconnections inside the circuit during the local test session. The system´s performance is explained by considering a typical application example, an operational amplifier in mixed bipolar/CMOS technology