Non-contact method for determining the presence of a contaminant in a semiconductor device

Abstract

The present invention provides a non-contact method for determining whether a contaminant is present in a semiconductor wafer having a substrate/dielectric interface formed thereon. in one advantageous embodiment, the method comprises field inducing a junction in equilibrium inversion in the semiconductor wafer device. A conventional corona source may be used to induce the junction to equilibrium inversion. This particular embodiment further includes forming a contaminant junction near the substrate/dielectric interface when the contaminant is present in the semiconductor wafer by adding charge and pulsing the junction out of equilibrium. A surface voltage measurement, which may be taken with a Kelvin probe, is obtained by measuring a change in a surface voltage as a function of time. The method further includes determining whether the contaminant is present in the semiconductor wafer from the change in the surface voltage. When the contaminant is present in the device, the change in the surface voltage is negligible. This negligible change is in stark contrast to the change in surface voltage that occurs in a non-contaminated device. The data obtained from these surface voltages can be plotted with conventional devices to yield the change in surface voltage with respect to time.