A pinned photodiode, which is a double pinned photodiode having increased electron
capacitance, and a method for forming the same are disclosed. The invention provides
a pinned photodiode structure comprising a substrate base over which is a first
layer of semiconductor material. There is a base layer of a first conductivity
type, wherein the base layer of a first conductivity type is the substrate base
or is a doped layer over the substrate base. At least one doped region of a second
conductivity type is below the surface of said first layer, and extends to form
a first junction with the base layer. A doped surface layer of a first conductivity
type is over the at least one region of a second conductivity type and forms a
second junction with said at least one region of a second conductivity type.
