Double well bipolar junction transistor for esd and surge protection

An ESD protection device comprising:

• a substrate having a first conductivity type, the substrate forming a collector of a bipolar junction transistor;
• an epitaxial region located above the substrate, the epitaxial region having a second conductivity type and forming a base of the bipolar junction transistor;
• a first well disposed at an upper surface of the epitaxial region, the first well having the first conductivity type and forming an emitter of the bipolar junction transistor;
• a base-contact region disposed at the upper surface of the epitaxial region, the base-contact region having a contact-region doping concentration of the second conductivity type that is greater than an epitaxial-region doping concentration of the second conductivity type of the epitaxial region;
• and
• a counter-doped region adjacent to the base-contact region and restricting at least in part a contact area between the base-contact region and the epitaxial region, the counter-doped region having a counter-doping concentration of the first conductivity type less than the epitaxial-region doping concentration of the second conductivity type of the epitaxial region.

A method for forming an ESD protection device, comprising:

• providing a substrate having a first conductivity type to form a collector of a bipolar junction transistor;
• forming an epitaxial region having a second conductivity type above the substrate to form a base of the bipolar junction transistor;
• disposing a first well having the first conductivity type at an upper surface of the epitaxial region to form an emitter of the bipolar junction transistor;
• disposing a base-contact region at the upper surface of the epitaxial region, the base-contact region having a contact-region doping concentration of the second conductivity type that is greater than an epitaxial-region doping concentration of the second conductivity type of the epitaxial region;
• and
• disposing a second well having the first conductivity type adjacent to the base-contact region to restrict at least in part a contact area between the base-contact region and the epitaxial region.