Patent ID: 6879176

Claim:
A method of determining leakage current of dielectric overlaying a semiconductor wafer comprising: (a) providing a semiconductor wafer having a dielectric overlaying at least part of the semiconductor wafer; (b) providing a probe having an elastically deformable conductive tip; (c) causing the probe tip to contact the dielectric; (d) applying a DC voltage having an AC voltage superimposed thereon between the probe tip and the semiconductor wafer; (e) sweeping the applied DC voltage having the AC voltage superimposed thereon from a first DC voltage toward a second DC voltage; (f) acquiring phase angles between the AC voltage and an AC current flowing through the dielectric in response to said AC voltage during the sweep of the DC voltage; (g) determining from the acquired phase angles, changes in a conductance of the semiconductor wafer and the dielectric as a function of changes in the voltage of the swept DC voltage; and (h) determining a leakage current of the dielectric from the changes in the conductance.