Patent ID: 7709329
Filing Date: 2010-05-04
Classification: H01L

Abstract:
1. A method of forming an electrostatic discharge (ESD) protection device having a desired breakdown voltage (BV), comprising: providing a semiconductor substrate having a first electrical conductivity type and a surface; forming a deep well having a second electrical conductivity type in the substrate; forming a shallow well having the second electrical conductivity type in the deep well; the shallow well having a higher dopant concentration than the deep well; a junction of the deep well with the shallow well at the surface defining a first surface junction; and a junction of the deep well with the substrate at the surface defining a second surface junction; following forming the deep well and the shallow well, forming an isolation region in the surface; the isolation region covering the first surface junction and a partial portion of the surface extending from the first surface junction to the second surface junction; and forming one of an anode or cathode region in the shallow well; the one of the anode or cathode region being of the second electrical conductivity type and having a higher dopant concentration than the shallow well; whereby the breakdown voltage is established by the amount of the partial portion covered by the isolation region.