ESD CIRCUIT WITH DIODE-CONNECTED TRANSISTOR

摘要

A diode-connected transistor device for IC protection against electrostatic discharge (ESD) that functions as a transistor in the active region during and ESD event. The device cell (10) includes annular collector (26) at the outer reaches of the cell, a circular base diffusion (32) concentric with the collector, and an annular emitter (34), near the outer edge of the base. The base and emitter regions are conected together by metallization (44), external to the transistor cell. With the base contact enclosed by the annular emitter during an ESD spike the initial reverse bias current flow is from the collector, under the emitter diffusion and out of the base contact. The active emitter area is significantly increased with only a small increase in transistor area, resulting in reduced power density and joule heating, and increased overall ESD tolerance without significant change in parasitic capacitance.