Semiconductor device manufacturing method and semiconductor device

A semiconductor device manufacturing method comprising:

• performing ion implantation of a first conductivity type to form a first well of the first conductivity type from a first depth of a substrate to a second depth greater than the first depth in the substrate;
• performing ion implantation of the first conductivity type on a first region of the substrate to form a second well of the first conductivity type at a third depth from a surface of the substrate in the first region of the substrate;
• performing ion implantation of a second conductivity type different from the first conductivity type on the first region of the substrate to form a third well of the second conductivity type underneath the second well in the first region of the substrate in a position overlapping with the first well located underneath the second well in the first region of the substrate;
• performing ion implantation of the second conductivity type on the first region of the substrate to form a fourth well, that surrounds the second well in a plan view and has the second conductivity type, at a fourth depth from the surface of the substrate in the first region of the substrate;
• performing ion implantation of the first conductivity type on a second region of the substrate to form a fifth well of the first conductivity type above the first well in the second region of the substrate;
• and
• performing ion implantation of the second conductivity type on the second region of the substrate to form a sixth well of the second conductivity type above the first well in the second region of the substrate,
• wherein:
• the substrate includes a third region;
• in the forming the third well, a seventh well of the second conductivity type is formed from a fifth depth of the substrate to a sixth depth greater than the fifth depth in the third region of the substrate by performing ion implantation of the second conductivity type;
• the seventh well is located in a position overlapping with the first well in the third region of the substrate;
• and
• in forming the fourth well, an eighth well of the second conductivity type is formed above the seventh well in the third region of the substrate by performing ion implantation of the second conductivity type in the third region of the substrate.