Patent ID: 7701012

Claim:
An electrostatic discharge (ESD) protection clamp having a principal surface, and having first and second protective terminals adapted to limit a voltage appearing across protected terminals of an integrated circuit (IC) to which the protective terminals are coupled, comprising: a bipolar transistor having an emitter of a first conductivity type coupled to the first protective terminal, a collector of the first conductivity type coupled to the second protective terminal and a base of a second, opposite conductivity type located between the emitter and collector, wherein the collector includes a first sinker region extending from the principal surface and a second sinker region extending from the principal surface; an integrated Zener diode having a first Zener terminal of the second conductivity type at the principal surface and ohmically coupled to the base, and a second Zener terminal of the first conductivity type at the principal surface and ohmically coupled to the collector; wherein: the first Zener terminal has a substantially annular ring shape at a periphery of the base, wherein a first Zener space charge region having a first width is defined between a first portion of the first Zener terminal and the first sinker region, and a second Zener space charge region having a second width is defined between a second portion of the first Zener terminal and the second sinker region, wherein the first width and the second width differ by a distance that is a function an angle of ion implementation, α, having a magnitude greater than zero degrees with respect to a normal to the principal surface; and the second Zener terminal has a substantially annular ring shape spaced apart from the first Zener terminal.