US Patent 10411004 Semiconductor device suitable for electrostatic discharge (ESD) protection

Semiconductor device and methods for making the devices includes a buried layer of a first conductivity in a substrate in which a distance between two adjacent ends can be selected to achieve a desired breakdown voltage. A deep well having a first doping concentration of a second conductivity type is implanted in an epitaxial layer above the two adjacent ends of the buried layer. A patterned doped region is formed in the deep well and extending into the epitaxial layer above and separated a distance from the two adjacent ends of the buried lay. The patterned doped region has a second doping concentration of the second conductivity type that is greater than the first doping concentration.