To detect soft breakdown of a dielectric layer of a semiconductor wafer, a DC current is caused to flow between a top surface of the dielectric layer and the semiconducting material of the semiconductor wafer. The DC current is either a constant value DC current, or a DC current that swept and/or stepped from a first value toward a second value in a manner whereupon the electric field and, hence, a DC voltage induced across the dielectric layer increases as the DC current approaches the second value. The response of the semiconductor wafer to the flow of DC current is measured for the presence of an AC voltage component superimposed on the DC voltage. The value of the DC voltage induced across the dielectric layer where the AC voltage component is detected is designated as the soft breakdown voltage of the dielectric layer.