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The dependence on geometry, extraction field, electron start energy, and rise time of the input signal is investigated for the transit-time and cross-talk effects in stroboscopic voltage measurements via electron emission. The investigation yields information about the best achievable time resolution and the disturbance of measured signals by signals on neighboring conductors in corresponding contactless voltage-measuring techniques like photoemission sampling and electron-beam sampling.

The idea of utilizing time -resolved photoemission for contactless electrical testing on internal nodes of IC's israther young. Initial studies quickly showed the advantages the technique offers over other methods. After a shortreview of the basic principle and its attractive features, this paper reports on the progress made toward meeting therequirements for IC testing and diagnostic equipment. The goals of IC testing are to provide high time and voltageresolutions 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 photoemissionprocess, these parameters are independent of the spatial resolution in the regime of interest. The investigation iscarried out with a pulsed -laser system generating picosecond pulses in the UV range. The measurements presentedwere performed on a photoconductive switch. This allows testing the time resolution of the method by ultra -fastsignals and generating the electric transients to be sampled by the same laser source as the sampling pulse. Thelatter point guarantees almost jitter -free operation. The results clearly demonstrate that photoemission sampling iscapable of contactless diagnostics and testing of very high -speed circuits with a high voltage resolution and shorttesting time.IntroductionThe major challenge for contactless IC testing is the combination of the three measuring parameters: 1) Timeresolution in the low picosecond range; 2) spatial resolution in the submicrometer range, and 3) voltage resolutionbelow 10 mV accomplished with short testing time as well as a wide range of applicability.Only a few years ago, was there just one feasible method to probe internal nodes of integrated circuits bycontactless means: electron beam probing.1-3 The ever -increasing switching speed and decreasing voltage swingsof modern high -speed electronic circuits have exceeded the performance limits of existing e-beam testing