Antiblooming structure for solid-state image sensor

Abstract

A solid-state image sensor includes a substrate of a semiconductor material of one conductivity type having a surface. A plurality of spaced, parallel CCDs are in the substrate at the surface. Each CCD includes a channel region of the opposite conductivity type in the substrate and a plurality of conductive gates extending across and insulated from the channel region. The conductive gates extend laterally across the channel regions of all of the CCDs and divide the channel regions into a plurality of phases and pixels. A drain region of the opposite conductivity type is in the substrate at the surface and extends along the channel region of at least one of the CCDs. A separate overflow channel region of the opposite conductivity type is in the substrate at said surface and extends from each of the CCD channel region phases to the adjacent drain region. A separate overflow barrier region of the one conductivity type is in the substrate and extends across an overflow channel region between the CCD channel region and the drain to control the flow of charge carriers from each phase of the CCD channel region to the drain. Each of the CCDs may have a separate drain region or two adjacent CCDs may share a common drain region. A CCD barrier region extends across the channel region in each phase. The CCD barrier region contains the same impurity concentration as the overflow-barrier region of its respective phase and may be connected to the overflow-barrier region.