High Speed Circuit Measurements Using Photoemission Sampling

We report the development of a new technique for measurement of high speed signals in electronic devices. The method is based on the energy analysis of electrons emitted from the surface of a metallization line on the device by multiphoton photoelectric effect in vacuum using a low powered, cw mode-locked laser source. Changes in the potential of the surface give rise to shifts in the photoemitted electron energies, which can be measured using a simple, retarding field electron energy analyzer. Since the method involves the direct measurement of voltage on a metal line, it can be used on any type of electronic device, regardless of the electronic material being used to fabricate the device. Furthermore, the opacity of the metal eliminates the possibility of perturbation of device performance by absorption of the laser radiation in the semiconductor.