Patent ID: 8664080

Claim:
A method for forming a vertical electrostatic discharge (ESD) protection device, comprising: depositing a multi-layer n-type epitaxial layer on a substrate having p-type surface including first epitaxial depositing to form a first n-type epitaxial layer on said p-type surface, and second epitaxial depositing to form a second n-type epitaxial layer formed on said first n-type epitaxial layer, wherein said first n-type epitaxial layer has a peak doping level which is at least double that of said second n-type epitaxial layer, said multi-layer n-type epitaxial layer providing an n-base for a PNP bipolar transistor of said vertical ESD protection device; forming a p+ layer on said second n-type epitaxial layer; etching through said p+ layer and said multi-layer n-type epitaxial layer to reach said substrate to form a trench; filling said trench with a filler material to form a trench isolation region, and forming a metal contact on said p+ layer for providing contact to said p+ layer.