Semiconductor devices and methods of manufacturing the same

A semiconductor device comprising:

• a first well region laterally separated from a second well region in a substrate;
• a shallow trench isolation (STI) structure laterally between the first well region and the second well region in the substrate;
• a first deep implant region of a first dopant type opposite to a dopant type of the first well region, and vertically lower than the STI structure;
• a second deep implant region of a second dopant type opposite to a dopant type of the second well region, and vertically lower than the STI structure;
• a first shallow implant region of the first dopant type, vertically over the first deep implant region, and laterally between the first well region and the STI structure;
• and
• a second shallow implant region of the second dopant type, vertically over the second deep implant region, and laterally between the second well region and the STI structure.

A method of manufacturing a semiconductor device, comprising:

• etching a shallow trench isolation (STI) trench in a substrate;
• forming a first well region and a second well region laterally at both sides of the STI structure in a substrate;
• forming a first implant region of a first dopant type opposite to a dopant type of the first well region, and vertically lower than the STI trench;
• and
• forming a second implant region of a second dopant type opposite to a dopant type of the second well region, and vertically lower than the STI trench.