Patent ID: 8421189

Claim:
An apparatus comprising: an internal circuit electrically coupled between a first node and a second node; and a protection device electrically coupled between the first node and the second node, wherein the protection device is configured to protect the internal circuit from transient electrical events, the protection device comprising: a buried layer having a doping of a first type; a first plug overlying the buried layer, and having a doping of the first type with a higher doping concentration than that of the buried layer, the first plug having an annular shape when viewed from above from the protection device; a first well overlying the buried layer, and laterally surrounded by the first plug, the first well having a doping of the first type with a lower doping concentration than that of the first plug; a second plug laterally surrounding the first plug, the second plug having a doping of a second type different from the first type; a first region disposed at least in an end portion of the first well opposite the buried layer, and electrically coupled to the first node, the first region having a doping of the second type with a higher doping concentration than that of the second plug; a second region disposed in a top portion of the second plug, and electrically coupled to the second node, the second region having a doping of the second type with a higher doping concentration than that of the second plug; and a resistor electrically coupled between the first region and the first plug, wherein the resistor is disposed outside the first region and the first plug.