Patent ID: 7683452

Claim:
An image sensor having a plurality of pixels, each of which includes a photoelectric conversion element and a detection transistor a threshold voltage of which fluctuates in accordance with electrical charge generated in the photoelectric conversion element, comprising: a second conductivity type shield region and a first conductivity type photoelectric conversion region below the shield region that constitute the photoelectric conversion element and are formed in a first conductivity type substrate; a first conductivity type well region that is formed in the substrate and linked to the photoelectric conversion region; a second conductivity type source region formed in the well region; a second conductivity type drain region that is formed surrounding the well region and the photoelectric conversion region; a ring-like gate electrode that is formed on the well region and surrounding said source region, and is positioned between said source region and drain region and between said source region and said photoelectric conversion region; and a potential pocket region, formed in the well region and below the ring-like gate electrode, for accumulating the electrical charge, wherein a width of a first part of the ring-like gate electrode located between the source region and the photoelectric conversion region is formed narrower than a width of a second part of the ring-like gate electrode located between the source region and the drain region.