Patent ID: 7579632

Claim:
An ESD device comprising: a semiconductor substrate of a first conductivity type and having a first doping concentration, the semiconductor substrate having first and second surfaces; a first semiconductor layer of a second conductivity type on the first surface of the semiconductor substrate, the first semiconductor layer having a first surface that is opposite to the first surface of the semiconductor substrate and having a second doping concentration; a first semiconductor region of the second conductivity type positioned between a first portion of the first semiconductor layer and the first surface of the semiconductor substrate, the first semiconductor region forming a zener diode with dopants of the semiconductor substrate; a first P-N diode formed in the first semiconductor layer and overlying a first portion of the first semiconductor region; a first blocking structure formed as a first closed polygon having a periphery that surrounds the first P-N diode; and a second P-N diode formed in the first semiconductor layer and external to the first closed polygon.