Solid-state imaging device, drive method thereof and electronic apparatus

A solid-state imaging device comprising:

• a plurality of photodiodes located at different depths in a unit pixel area of a substrate, the substrate having two oppositely facing faces;
• a vertical transistor, the vertical transistor extending in a vertical direction from a first face of the substrate;
• a gate electrode of the vertical transistor, wherein the gate electrode extends vertically to a depth corresponding to a depth of a deepest one of the photodiodes, and wherein the gate electrode extends through depths corresponding to each of the photodiodes;
• an overflow path extending vertically and in contact with each of the photodiodes;
• and
• a floating diffusion region at a surface of the first face of the substrate.

A method for driving a solid-state imaging device, comprising:

• forming a solid-state imaging device including a plurality of photodiodes located at different depths in a unit pixel area of a substrate, the substrate having two oppositely facing faces;
• forming a vertical transistor from a first face of the substrate so that a gate electrode portion for reading signal charges obtained by photoelectric conversion in the plurality of photodiodes extends to depths corresponding to each of the photodiodes;
• forming an overflow path in contact with each of the plurality of photodiodes;
• forming a floating diffusion region at a surface of the first face of the substrate;
• and
• reading signal charges accumulated in the plurality of photodiodes, wherein a first one of the plurality of photodiodes is saturated, and wherein charges exceeding the saturation charge amount of the at least one of the plurality of photodiodes are passed to another one of the plurality of photodiodes by the overflow path.

An electronic apparatus, comprising:

• an optical lens system;
• a solid-state imaging device including a plurality of photodiodes located at different depths in a unit pixel area of a substrate, the substrate having two oppositely facing faces, wherein the optical lens system directs incident light to the solid-state imaging device;
• a vertical transistor, the vertical transistor extending in a vertical direction from a first face of the substrate;
• a gate electrode of the vertical transistor, wherein the gate electrode extends vertically to a depth corresponding to a depth of a deepest one to the photodiodes, and wherein the gate electrode extends through depths corresponding to each of the photodiodes;
• a floating diffusion region on a surface of the first face of the substrate;
• an overflow path extending vertically and in contact with each of the photodiodes in the plurality of photodiodes;
• and
• a signal processing device which processes output signals from the solid-state imaging device.