Patent ID: 7968907

Claim:
An over-voltage protection thyristor device, comprising: a substrate semiconductor material of a first conductivity type, the substrate having a first outer surface and a second outer surface; a first shallow base region of a second conductivity type extending from the first outer surface into the substrate; a second shallow base region of a second conductivity type extending from the second outer surface into the substrate; an emitter of the first conductivity type extending from the first outer surface into the shallow base region, the emitter having a depth that is less than the first shallow base region; a deep base region of the second conductivity type extending into the substrate from the second shallow base region, the deep base region having a graded doping concentration reducing into the substrate such that the capacitance between the deep base region and the substrate is reduced; and a buried plug region of the first conductivity type vertically aligned with the emitter and extending from the first shallow base region into the substrate, the buried region having a higher doping concentration than the substrate.