Patent ID: 7642772

Claim:
A non-contact method for measurement of leakage current of a p-n junctions of a semiconductor test structure in a scribe line of an IC product wafer comprising: locating the test structure and moving the test structure beneath a probe electrode, illuminating of a test area of a semiconductor test p-n junction structure with an intensity modulated light to obtain a linear dependence of a JPV signal from a transparent electrode versus light flux, with a photon energy larger than the semiconductor band gap, monitoring junction photo-voltage from the illumination area, means for measuring a reference photo-voltage from the reference p-n structure having a planar p-n diode with a known junction capacitance, measuring the photo-voltage from the test p-n structure using at least two light modulation frequencies, and determining of the leakage current of the test p-n junction structure using the photo-voltage, reference photo-voltage and junction capacitance of the reference p-n structure, wherein the probe-junction distance is fixed by the thickness of a thin transparent insulating layer coating the probe electrode and placed in close proximity with the test p-n junction and where the electrical effect of this dielectric film is determined by a probe capacitance calibration using a known voltage signal applied to the wafer without light illumination.