Photoemission sampling technique for high-speed integrated-circuit testing

Abstract

After a short review of the basic principles of time-resolved photoemission and its capabilities as a method for contactless electrical testing of integrated circuits, this paper reports on the progress made toward meeting the requirements for integrated-circuit (IC) testing and diagnostic equipment. The goals of IC testing are to provide high time and voltage resolutions with short testing time, and simultaneously high spatial resolution independent of the circuit technology (Si, GaAs). Here, the emphasis is on the time and voltage resolutions and short testing time. In the photoemission process, these parameters are independent of the spatial resolution in the regime of interest. The investigation is carried out with a pulsed-laser system generating picosecond pulses in the UV range. The measurements presented were performed on photoconductive switches. This allows testing the time resolution of the method by ultra-fast signals, and generating the electric transients to be sampled by the same laser source as the sampling pulse, guaranteeing almost jitter-free operation. The results clearly demonstrate that photoemission sampling is capable of contactless diagnostics and testing of very high-speed circuits with a high-voltage resolution and short testing time. © 1987 Elsevier Science Publishers B.V. (North-Holland).