A rapid assessment technique for SOI substrates

Anomalous device behaviour such as the kink effect is related to device parameters such as carrier lifetime and device dimensions. Simple experimental techniques to extract these parameters have been developed. The basic test structure consists of an MOS capacitor fabricated by evaporating an array of metal dots onto an oxidized SOI substrate. The first measurement consists of a single, high-frequency capacitance-voltage plot, from which the thicknesses of buried oxide and active body region and substrate doping can be deduced. Capacitance transient measurements are then performed in which the relaxation of the SOI capacitor system after a fast-rise time, depleting-voltage step is monitored. The transient is affected by charge generation processes occurring in both the substrate and the body. A physical model has been developed to account for these phenomena, and the validity of the techniques has been demonstrated by independent measurements