A method for the determination of the generation sources, bulk lifetime, and surface generation velocity using MOS capacitor

Various pulsed MOS capacitance techniques have been developed for the determination of the generation lifetime and the surface generation velocity in semiconductors. A method that uses a new approach to surface generation velocity evaluation is described. The pulsed MOS capacitor is routinely used to measure generation lifetime. The high-frequency capacitance transient observed after the MOS capacitor has been pulsed from accumulation into deep depletion, is usually analyzed to determine the value of bulk generation lifetime in the semiconductor concerned. The method proposed is based upon a precise MOS structure model incorporating lateral effects, the diffusion current from the bulk, and the decrease of the surface generation velocity during the measurement process. The method uses a single measurement of the nonequilibrium C-t characteristic in MOS capacitors subjected to voltage stress and is particularly useful when applied to small gate diameter MOS samples with long relaxation times.