Solid-state image sensor, imaging device, and electronic device

A light detecting device comprising:

• a photoelectric converter configured to generate a charge corresponding to incident light;
• a transfer transistor;
• a floating diffusion configured to receive the charge via the transfer transistor;
• a charge accumulation region;
• a switching transistor disposed between the floating diffusion and the charge accumulation region in a first direction, wherein the switching transistor is configured to electrically connect the floating diffusion and the charge accumulation region;
• an amplification transistor;
• a selection transistor, and
• wherein the floating diffusion is connected to a vertical signal line via the amplification transistor and the selection transistor,
• wherein the amplification transistor is disposed between the switching transistor and the selection transistor in the first direction,
• wherein a gate of the transfer transistor has an elongated shape in a plan view, a long side of the elongated shape extending in the first direction, and
• wherein the long side of the elongated shape is longer in the first direction than a length of a region including the floating diffusion, the charge accumulation region and the switching transistor.

A light detecting device comprising:

• a photoelectric converter configured to generate a charge corresponding to an incident light;
• a floating diffusion;
• a transfer transistor disposed between the photoelectric converter and the floating diffusion and transferring the charge from the photoelectric converter to the floating diffusion, wherein a gate of the transfer transistor has two short sides and two long sides;
• a charge accumulation region;
• a switching transistor disposed between the floating diffusion and the charge accumulation region, wherein the switching transistor is configured to electrically connect the floating diffusion and the charge accumulation region;
• and
• a reset transistor connected to the floating diffusion and resetting the floating diffusion to a power supply voltage,
• wherein the charge accumulation region, the switching transistor and the floating diffusion are arranged in this order and along a line that is parallel to one of the long sides of the gate of transfer transistor, and
• wherein the length of the long side is longer than a length of a region including the floating diffusion, the charge accumulation region, the reset transistor and the switching transistor.