A MECHANISM AND A REDUCTION TECHNIQUE FOR LARGE REVERSE LEAKAGE CURRENT IN P-N-JUNCTIONS

The origin of anomalously large p-n junction leakage current in Si is investigated. The leakage has strong electric field dependence, and we ak temperature dependence and therefore cannot be explained by either generation-recombination current or diffusion current. It may be expla ined by the local Zener effect at local enhancement of the electric fi eld around small precipitates in the depletion layer. Supposing a sphe rical precipitate, the electric field will be enhanced as much as 1.3 times for a SiO2 precipitate and 3 times for a metal precipitate. The leakage features are explained by the electric held dependence and the temperature dependence of the local Zener probability. A new approach to reduce the local Zener probability by controlling the profile of t he electric field is proposed, and the validity of the approach is con firmed by direct experiment and by improvement in the refresh operatio n of DRAM cells.