Structures for an electrostatic discharge protection device

A method of forming a structure for an electrostatic discharge protection device, the method comprising:

• forming a first gate over a semiconductor substrate;
• forming a shallow trench isolation region in the semiconductor substrate;
• forming a second gate over the semiconductor substrate, wherein the second gate is disposed adjacent to the first gate;
• forming a source adjacent to the first gate, wherein the source includes a first well in the semiconductor substrate, a second well in the semiconductor substrate, a third well in the semiconductor substrate, and a first doped region, the first well and the first doped region have a first conductivity type, the second well has a second conductivity type opposite from the first conductivity type, the third well has the first conductivity type at a lower dopant concentration than the first well, the first well is disposed between the third well and the first doped region, the first well has a corner that is disposed beneath the shallow trench isolation region, the third well includes a portion beneath the first well, the third well wrapping about the corner of the first well, the first doped region has a first portion that overlaps with the first well, and the first doped region has a second portion that overlaps with the second well;
• and
• forming a drain adjacent to the second gate,
• wherein the first gate and the second gate are laterally between the source and the drain.