Solid-state imaging device and camera

A camera comprising:

• a solid-state imaging device that receives light from a first substrate surface side of a substrate;
• an optical system that guides incident light to the first substrate surface side of the solid-state imaging device;
• and
• a signal processing circuit that processes an output signal of the solid-state imaging device, wherein
• the solid-state imaging device includes pixel cells that are formed on the substrate having the first substrate surface side, on which light is irradiated, and a second substrate surface side, on which elements are formed, and separated by an adjacent cell group and an element separation layer for each of the pixel cells or with plural pixel cells as a unit,
• each of the pixel cells includes:
• a first conductive well formed on the first substrate surface side;
• and
• a second conductive well formed on the second substrate surface side,
• the first conductive well receives light from the first substrate surface side and has a photoelectric conversion function and a charge accumulation function for the received light, and
• a transistor that detects accumulated charges in the first conductive well and has a threshold modulation function is formed in the second conductive well.