Low capacitance SCR with trigger element

In an integrated circuit, a silicon rectifier for providing electrostatic discharge protection to another circuit element, comprising:

• a first well region of a first conductivity type formed within a semiconductor body;
• a first region of the first conductivity type formed within the first well region;
• a second region of a second conductivity type formed within the first well region;
• a second well region of the second conductivity type formed within the semiconductor body adjacent to the first well region;
• a third region of the first conductivity type formed within the second well region;
• a fourth region of the second conductivity type formed within the second well region;
• and
• isolation regions formed within the semiconductor body respectively isolating the second well region from the first well region, the second region from the first region, and the fourth region from the third region;
• wherein the second region is connected to a terminal of the other circuit element;
• the first, third and fourth regions are connected to a reference potential terminal;
• the second region, first well region and semiconductor body are dimensioned and configured to act as a first transistor having an emitter connected through the second region to the protected device terminal, a base connected through resistance of the first well region and the first region to the reference potential terminal, and a collector connected through resistance of the semiconductor body and the fourth region to the reference potential terminal;
• and
• the third region, second well region and first well region are dimensioned and configured to act as a second transistor having an emitter connected through the third region to the reference potential terminal, a base connected through the semiconductor body to the base of the first transistor, and a collector connected to the base of the first transistor;
• whereby application of a voltage difference between the other circuit element terminal and the reference potential terminal of at least a trigger voltage level will switch the silicon rectifier by forward injection from a deactivated state to an activated state to divert current away from the other circuit element to the reference potential terminal through the silicon rectifier.