Solid state image sensing device for enhanced charge carrier accumulation

Claim 1

A charge coupled image sensing device comprising: a semiconductor substrate of one conductivity type; an insulating layer formed on a surface of said semiconductor substrate; a photosensitive section including a first portion of said substrate, a plurality of photosensitive channel layers of the opposite conductivity type formed in the first portion adjacent to said surface and mutually isolated and arranged in a row, and a single charge accumulating electrode formed on said insulating layer, overlaid on the row of photosensitive channel layers and maintained at a constant potential, said photosensitive section producing charge carriers and accumulating the charge carriers in photosensitive potential wells formed in the first portion of said substrate; a CCD charge transfer readout section including a second portion of said substrate, a buried channel layer of the opposite conductivity type formed in a second portion of said substrate adjacent to said surface and spaced apart from said row of photosensitive channel layers and a plurality of charge transfer electrodes formed on said insulating layer, overlaid on the buried channel layer and supplied with clock pulses, said CCD charge transfer readout section temporarily accumulating shifted charge carriers in transfer potential wells for subsequent transference which are deeper than the photosensitive potential wells and are formed in the second portion of said substrate; a charge shift section including a third portion of said substrate between the first and second portions and a single charge shift electrode formed on said insulating layer, overlaid on the surface of the third portion of said substrate and overlaying a portion of the adjacent side edges of the charge transfer electrodes and the charge accumulating electrode and supplied with a clock pulse, said charge shift section lacking a channel layer between said photosensitive channel layers and said barrier channel layer of said CCD charge transfer section, in said charge shift section when the charge shift electrode is maintained at a predetermined potential, a barrier being provided in the third portion between the photosensitive potential wells and the transfer potential wells and when the charge shift electrode is maintained at another potential, a shift potential well which is deeper than the photosensitive potential wells and shallower than the transfer potential wells being formed in the third portion so that the produced change carriers are shifted from the photosensitive potential wells to the transfer potential wells through the shift potential wells; and an output section formed in the second portion of said substrate and electrically connected to said CCD charge transfer section to receive the charge carriers from said CCD charge transfer section.