Semiconductor structure and electrostatic discharge protection circuit

A semiconductor structure corresponding to a first diode and a second diode, wherein the first diode and the second diode are connected in series, wherein the semiconductor structure comprises:

• a first deep well region disposed on a substrate;
• a first well region disposed on the first deep well region;
• two second well regions disposed at two sides of the first well region respectively;
• a first doping region disposed on the first well region;
• a second doping region disposed on the first well region, wherein a first isolation region is disposed between the first doping region and the second doping region;
• a second deep well region disposed on the substrate;
• a third well region disposed on the second deep well region;
• two fourth well regions disposed at two sides of the third well region respectively;
• a third doping region disposed on the third well region;
• and
• a fourth doping region disposed on the third well region, wherein a second isolation region is disposed between the third doping region and the fourth doping region, wherein the second doping region is connected to the third doping region,
• wherein the second deep well region is separated from the first deep well region,
• wherein the first deep well region and the second deep well region are N type or P type, and
• wherein the substrate comprises a protrusion portion, and the protrusion portion is between the second deep well region and the first deep well region.