STRUTTURA DI TRANSISTORE V(BR)CEO PROTETTO PER IL CASO DI INVERSIONE DELLE POLARITA' DI ALIMENTAZIONE E PRODOTTO RISULTANTE

摘要

A lateral PNP transistor with concentric p-doped emitter and collector diffusion zones in an n-doped base layer epitaxially grown on a p-type silicon substrate, covered by a layer of silicon oxide, has emitter and collector electrodes in the form of metallic patches on the oxide layer overlying the respective diffusion zones and penetrating the oxide at limited contact areas. The metallic patches extend above an annular base-layer portion separating the two diffusion zones and symmetrically approach a circular centerline of this annular portion in order to guard against punch-through upon accidental polarity reversal of the collector/emitter voltage. A narrow peripheral gap in the collector electrode is traversed by an elongate metal strip which forms a radial extension of the emitter electrode leading to a supply terminal, the spacing of that strip from the gap edges substantially equaling the radial distance between the confronting peripheral boundaries of the two patches. If the diffusion zone of the collector is peripherally continuous instead of being interrupted in the region of the gap of the overlying electrode, the gap is bridged by a stratum of p-doped polycrystalline silicon embedded in the oxide layer and in conductive contact with the collector electrode on opposite sides of the gap, this stratum having an edge complementing the inner boundary of the metallic collector patch to a full circle around the emitter patch.