Laser voltage probe (LVP): a novel optical probing technology for flip-chip packaged microprocessors

A novel optical probing technique to measure voltage waveforms from flip-chip packaged CMOS integrated circuits (IC) is described. This IR laser based technique allows signal waveform acquisition and high frequency timing measurements directly from active P-N junctions through the silicon backside substrate on ICs mounted in flip-chip stand-alone or multi-chip module packages as well as wire-bond packages on which the chip backside is accessible. The technique significantly improves silicon debug and failure analysis (FA) throughput time (TPT) as compared to backside electron-beam (e-beam) probing because of the elimination of backside trenching and probe hole generation operations.