Semiconductor device having a double deep well and method of manufacturing same

A method of forming a semiconductor device, the method comprising:

• implanting ions having a second dopant type into a substrate to form a deep well, wherein the substrate has a first dopant type;
• growing an upper portion over the substrate, wherein the upper portion is over the deep well;
• implanting ions having the first dopant type in the upper portion to form a first well;
• implanting ions having the second dopant type in the upper portion to form a second well, wherein the second well is in contact with the first well;
• and
• forming a gate structure over the first well.

A method of forming a semiconductor device, the method comprising:

• implanting ions having a second dopant type in a substrate to form a first deep well, wherein the substrate has a first dopant type;
• implanting ions having the second dopant type in the substrate to form a second deep well, wherein an energy for implanting ions to form the second deep well is less than an energy for implanting ions to form the first deep well;
• implanting ions having the first dopant type in the substrate to form a first well, wherein a dopant concentration in the first well is greater than or equal to a dopant concentration in the first deep well;
• and
• forming a gate structure over the first well.