PLANAR SEMICONDUCTOR DEVICES HAVING PN JUNCTIONS

摘要

In planar silicon semiconductor devices of the PN junction type, field plates (19, 20) overlie the silicon dioxide-silicon nitride film on the device surface to inhibit inversion formation of conductive channels on the device surface. The field plates are connected to a more heavily doped zone (12) on one side of a PN junction and extend some distance over the lightly doped zone (13) on the other side of the PN junction. At high reverse biases, the presence of trapping centers produces a charge level at the device surface, resulting in current channeling which produces excessive reverse leakage current. This effect is avoided or reduced by omitting the silicon nitride layer in a portion (22, 23) overlying the more lightly doped zone and spaced away from the PN junction boundary (38, 39). This omission eliminates a portion of the oxide-nitride interface which appears to be the locus of such trapping centers.