Image sensor having a lateral photodetector structure and forming method thereof

The present disclosure relates to an image sensor including a first semiconductor layer having a first doping type. A second semiconductor layer having the first doping type is between sidewalls of the first semiconductor layer and extends vertically along the sidewalls of the first semiconductor layer from a bottom side of the first semiconductor layer toward a top side of the first semiconductor layer. A first doped region having the first doping type is in the first semiconductor layer and laterally beside the second semiconductor layer. The first doped region extends vertically along a sidewall of the second semiconductor layer. A second doped region having a second doping type is in the first semiconductor layer and laterally beside the first doped region. The second doped region extends vertically along a side of the first doped region and forms a p-n junction with the first doped region.