Image sensor

An image sensor, comprising:

• a semiconductor layer having a front surface and a back surface;
• a photodiode disposed in the semiconductor layer;
• a floating diode disposed apart from the photodiode in the semiconductor layer;
• a storage diode disposed between the photodiode and the floating diode in the semiconductor layer;
• an insulating layer disposed on the front surface of the semiconductor layer;
• a first gate disposed on the front surface of the semiconductor layer and in the insulating layer, the first gate being configured to serve as a transfer transistor;
• a second gate disposed on the front surface of the semiconductor layer and in the insulating layer, the second gate overlapping the storage diode;
• and
• a third gate disposed on the front surface of the semiconductor layer and in the insulating layer, the third gate being configured to serve as a reset transistor.

An image sensor, comprising:

• a semiconductor layer having a front surface and a back surface;
• a photodiode and a floating diode disposed apart from each other in the semiconductor layer;
• an insulating layer disposed on the semiconductor layer;
• a wiring layer disposed in the insulating layer;
• and
• a first gate and a transfer gate disposed in the insulating layer between the wiring layer and an interface between the insulating layer and the semiconductor layer.