Semiconductor device and process for producing the same

Claim 1

A photosensor comprising, in a semiconductor substrate of a first conductivity type, a photodiode composed of a semiconductor domain of a conductivity type opposite of the first conductivity type, all of a lower surface and sides of said photodiode being surrounded by a semiconductor domain of the conductivity type opposite of the first conductivity type and of a high impurity concentration, and a semiconductor domain of the first conductivity type forming a junction with said semiconductor domain of the conductivity type opposite of the first conductivity type, wherein said photodiode is separated from other semiconductor elements by a separating domain composed of a semiconductor of the first conductivity type, wherein said other semiconductor elements include a transistor adjacent to said photodiode, with said transistor comprising a buried region and a diffusion region extending from a surface of said substrate to the buried region, and the diffusion region being arranged at one side of a base region, with said photodiode being arranged at the opposite side of said base region.