Image sensor and driving method thereof

An image sensor comprising:

• a semiconductor substrate comprising a photoelectric conversion region and a first floating diffusion region;
• a first vertical transfer transistor extending along a thickness direction of the semiconductor substrate and penetrating at least a portion of the semiconductor substrate;
• a first region between the first floating diffusion region at a first side of the first vertical transfer gate and the photoelectric conversion region, the first region having a first conductivity type;
• a second region configured to have a second conductivity type at a second side of the first vertical transfer gate;
• a charge storage at the second side of the first vertical transfer gate;
• and
• an overflow transistor between the first vertical transfer gate and the charge storage element.

A driving method of an image sensor, comprising:

• generating first photoelectric charges during a first period in a photoelectric device connected to a first node;
• transferring the first photoelectric charges to a charge storage connected to the first node through a first region at a first side of a vertical transfer gate and having a first conductivity type;
• generating second photoelectric charges in the photoelectric device during a second period;
• transferring the second photoelectric charges to a second node through a second region at a second side of the vertical transfer gate and having a second conductivity type;
• and
• generating a pixel signal based on the charges accumulated in the second node.