Semiconductor device and method of manufacturing semiconductor device

A semiconductor device comprising:

• a first device isolation insulating film defining a first region and a second region in a semiconductor substrate;
• a first conductive layer of a first conductivity type formed in the first region of the semiconductor substrate and being shallower than a bottom of the first device isolation insulating film;
• a second conductive layer of the first conductivity type formed in the second region of the semiconductor substrate and being shallower than the bottom of the first device isolation insulating film;
• a third conductive layer of a second conductivity type formed in the semiconductor substrate below the first conductive layer and the second conductive layer and being deeper than the bottom of the first device isolation insulating film;
• a semiconductor layer formed above the semiconductor substrate and including
• a fourth conductive layer of the first conductivity type formed in a third region, which is a first part of the first region, connected to the first conductive layer,
• a fifth conductive layer of the first conductivity type formed in a fourth region, which is a second part of the second region, connected to the second conductive layer,
• a sixth conductive layer of the first conductivity type formed in a fifth region, which is a third part of the first region, connected to the first conductive layer,
• a seventh conductive layer of the first conductivity type formed in a sixth region, which is a fourth part of the second region, connected to the second conductive layer, and
• an eighth conductive layer of the second conductivity type formed in a seventh region between the third region and the fourth region in contact with the first device isolation insulating film;
• a second device isolation insulating film formed in the semiconductor layer and isolating the second conductive layer, the third conductive layer and the sixth conductive layer and the fourth conductive layer, and isolating the second conductive layer, the third conductive layer and the sixth conductive layer and the fifth conductive layer;
• a first gate insulating film formed above the second conductive layer;
• a second gate insulating film formed above the third conductive layer;
• a first gate electrode formed above the first gate insulating film and electrically connected to the first conductive layer via the fourth conductive layer;
• and
• a second gate electrode formed above the second gate insulating film and electrically connected to the second conductive layer via the fifth conductive layer.

A method of manufacturing a semiconductor device comprising:

• forming, in a semiconductor substrate, a first device isolation insulating film defining a first region;
• forming a semiconductor layer above the semiconductor substrate with the first device isolation insulating film formed in;
• forming, in the semiconductor layer, a second device isolation insulating film defining a second region containing a first part of the first region, and a third region containing a second part of the first region;
• forming, in the semiconductor substrate and the semiconductor layer, a first well of a first conductivity type which is deeper than a bottom of the second device isolation insulating film and shallower than a bottom of the first device isolation insulating film;
• forming a gate insulating film above the second region of the semiconductor layer;
• and
• forming, above the gate insulating film, a gate electrode electrically connected to the first well via the third region of the semiconductor layer.