Degradation mechanism for silicon p+-n junctions under forward bias

Leakage current degradation has been observed during forward bias stressing of silicon integrated p⁺-n junctions. Detailed characterization results of the anomalous leakage behavior are discussed in this paper. From these results an electric field-enhanced impurity diffusion mechanism has been proposed to explain both the strong temperature and forward bias dependencies on leakage current time-to-saturation. An activation energy has been determined for this mechanism (0.48±0.04 eV) and is in good agreement with that previously determined for diffusion of interstitial copper in p-type silicon. Subsequent Secondary Ion Mass Spectrometer elemental analysis has confirmed the presence of copper near the surface of the epitaxial layer containing the p⁺-n device.