Image sensor and manufacturing method thereof

An image sensor, comprising:

• a photosensitive device;
• a storage device, adjacent to the photosensitive device, comprising:
• a substrate;
• a P-N junction, embedded in the substrate;
• a gate electrode, covering the P-N junction;
• and
• a shielding structure, disposed over the substrate and electrically isolated from the gate electrode, wherein the shielding structure comprise:
• a first shielding layer, comprising a first portion disposed over the substrate with a recess penetrating therethrough, wherein a projection of the first portion is overlapped with a projection of the gate electrode on a plane along a stacking direction of the substrate and the gate electrode, wherein the first shielding layer is made of a semiconductor layer;
• and
• a second shielding layer, covering the first shielding layer;
• a driving circuit, adjacent to the storage device;
• and
• an interconnect, disposed over and electrically coupled to the photosensitive device, the storage device, and the driving circuit.