Semiconductor device and manufacturing method of semiconductor device

A manufacturing method of a semiconductor device, comprising:

• forming a first transistor on a first wafer;
• forming a first pad that is electrically connected to the first transistor of the first wafer above the first transistor;
• forming a first diffusion layer and a second diffusion layer within a second wafer;
• forming an isolation insulating film or an isolation trench that extends at least from an upper surface of the second wafer to a lower surface of the second wafer within the second wafer and that isolates the first diffusion layer from the second diffusion layer;
• forming a second pad that is electrically connected to at least one of the first diffusion layer and the second diffusion layer above the second wafer;
• bonding the first wafer and the second wafer so that the second pad is disposed on the first pad;
• and
• forming a chip by dicing the bonded wafers.

A semiconductor device comprising:

• a first chip including:
• a first pad;
• and
• a first substrate that includes a first diffusion layer and a second diffusion layer, at least one of the first and second diffusion layers being electrically connected to the first pad;
• and
• a first isolation insulating film disposed between a portion of the first diffusion layer and a portion of the second diffusion layer;
• and
• a second chip including:
• a second pad that is provided on and electrically connected to the first pad;
• a second substrate that is provided above the second pad and that includes a third diffusion layer and a fourth diffusion layer, at least one of the third diffusion layer and fourth diffusion layer being electrically connected to the second pad;
• and
• a second isolation insulating film that extends at least from an upper surface of the second substrate to a lower surface of the second substrate within the second substrate and that isolates the third diffusion layer from the fourth diffusion layer.