Abstract: The described invention is directed to microwave methods for burning-in, electrical stressing, thermal stressing and reducing rectifying junction leakage current in fully processed semiconductor chips individually and at wafer level, as well as burning in and stressing semiconductor chip packaging substrates and the combination of a semiconductor chip mounted onto a semiconductor chip packaging substrate. Microwaves burn-in devices in a substantially shorter period of time than conventional burn-in techniques and avoid the need for special workpiece holders which are required by conventional stress and burn-in techniques. Additionally, microwave methods are described for reducing the leakage current of recitfying junctions, such as PN junctions and Schottky barrier diode junctions of semiconductor devices on fully processed semiconductor chips and wafers.