Patent ID: 7576370

Claim:
An apparatus that discharges an electrostatic charge, the apparatus comprising: a semiconductor integrated circuit, the semiconductor integrated circuit including: an input; a ground connection that provides a discharge path for the electrostatic charge; and an electrostatic discharge device connected between the input and the ground connection that has low leakage at an operating voltage, a positive trigger voltage, a positive clamping voltage, and wherein the positive clamping voltage is substantially independent of the positive trigger voltage, such that the device turns on in order to dissipate the electrostatic charge, the device including: an N+ substrate region that is connected to the ground connection, a P epitaxial region that is formed over the N+ anode region that has a thickness and a doping concentration that together substantially determine the positive clamping voltage, and an N+ electrode region that is formed within the P epitaxial region, such that a side wall surface of the N+ electrode region around a side wall surface of the P epitaxial region, the N+ electrode region connected to the input; and a P+ sidewall region formed over the P epitaxial region in a continuous region adjacent the sidewall surface of the N+ electrode region, wherein the P+ sidewall region and the N+ electrode form a zener diode that injects current into the P epitaxial region and thereby causes turn-on of a transistor formed by the N+ electrode region, the P region and the N+ substrate region, wherein a concentration of the P+ sidewall region assists in determining the positive trigger voltage without substantially having an effect on the positive clamping voltage.