INFLUENCE OF METAL IMPURITIES ON LEAKAGE CURRENT OF SI N+P DIODE

Dependence of the leakage current of Si N+P diodes on the surface metal (Cu, Ni or Fe) concentration after quantitative contamination was investigated, and the causes of the leakage current were studied by SIMS, TEM and optical microscopy. Cu was gettered in the N+ area, forming many large dislocations in the N+ area and inducing some dislocations in the substrate near the junction; thus, the leakage current increased remarkably. Ni was gettered in the N+ area also, but did not form large dislocations, so the leakage current did not increase. Fe was not gettered easily, and hence the leakage current increased corresponding to the Fe concentration.