Internally triggered electrostatic device clamp with stand-off voltage

摘要

An ESD protection device including a compound transistor structure having a trigger transistor and an ESD protection transistor. The trigger transistor includes a breakdown potential between the standoff voltage of a circuit to be protected and the breakdown potential of the ESD protection transistor. When activated, the trigger transistor operates to turn on the ESD protection transistor that is designed to carry the bulk of the conduction current associated with an ESD event. The trigger transistor is designed with an internal gain mechanism to ensure that it will not be turned off when a modified snapback voltage is reached during the ESD protection transistor operation. The trigger transistor is a minor contributor to the conducting current with the ESD protection transistor after such time as protection circuit operation acts. A process for fabricating a suitable compound transistor structure is disclosed.