Method of fabricating an esd protection device

Abstract

An ESD protection structure that when connected between an input/output pad on a semiconductor substrate and a reference voltage source, will protect internal circuits formed on the semiconductor substrate from over stress due to excessively high voltages of an ESD voltage source. The ESD protection structure has a uniform discharge current to prevent damage to the ESD protection device thus allowing increased protection to the internal circuits. The ESD protection device has at least one source region that is the emitters of parasitic transistors connected to the reference voltage source and at least one drain region that is the collectors of the parasitic transistors connected to the junction of the input/output pad and the internal circuitry. The ESD protection device further has at least one gate electrode formed above a channel region. The channel region is the region is between each of the source regions and the drain regions. The gate electrodes are connected to the reference voltage source. Each gate electrode has a variable length and thus the channel region has a variable length. The channel region is the base of the parasitic transistors formed by the ESD protection structure. The variable length of the channel region and thus the base of the parasitic transistors create an ESD current that is distributed uniformly over said ESD protection structure.