Solid-state image pickup element and solid-state image pickup device having a transfer electrode formed on the entire sidewall of a hole
A solid-state image pickup element comprises a first-conductive type planar semiconductor layer formed on a second-conductive type planar semiconductor layer, a hole portion formed in the first-conductive type planar semiconductor layer to define a hole therein, and a first-conductive type high-concentration impurity region formed in a bottom wall of the hole portion. The solid-state image pickup element also includes a first-conductive type high-concentration impurity-doped element isolation region, a second-conductive type photoelectric conversion region, a transfer electrode formed on the sidewall of the hole portion through a gate dielectric film, a second-conductive type CCD channel region, and a read channel formed in a region of the first-conductive type planar semiconductor layer sandwiched between the second-conductive type photoelectric conversion region and the second-conductive type CCD channel region.
1. A solid-state image pickup element comprising:
a first-conductive type planar semiconductor layer;
a second-conductive type planar semiconductor layer on which the first-conductive type planar semiconductor layer is formed;
a hole formed in the first-conductive type planar semiconductor layer;
a first-conductive type high-concentration impurity region formed in a bottom wall of the hole of the first-conductive type planar semiconductor layer;
a first-conductive type high-concentration impurity-doped element isolation region formed in a sidewall of the hole of the first-conductive type planar semiconductor layer, and connected to the first-conductive type high-concentration impurity region;
a second-conductive type photoelectric conversion region formed in the first-conductive type planar semiconductor layer located beneath the first-conductive type high-concentration impurity region and in a lower region of the sidewall of the hole of the first-conductive type planar semiconductor layer, and adapted to change a charge amount upon receiving light, wherein the second-conductive type photoelectric conversion region has an impurity concentration less than 1×10 18 cm −3 ;
a transfer electrode formed on the entire sidewall of the hole of the first-conductive type planar semiconductor layer through a gate dielectric film, wherein the transfer electrode is formed on the sidewall where the first-conductive type high-concentration impurity-doped element isolation region is formed;
a second-conductive type CCD channel region formed in a top surface of the first-conductive type planar semiconductor layer and in an upper region of the sidewall of the hole of the first-conductive type planar semiconductor layer; and
a read channel formed in a region of the first-conductive type planar semiconductor layer sandwiched between the second-conductive type photoelectric conversion region and the second-conductive type CCD channel region.
2. A solid-state image pickup device comprising a plurality of the solid-state image pickup elements as defined in claim 1 , wherein the solid-state image pickup elements are arranged in a matrix array.
3. The solid-state image pickup device as defined in claim 2 , which comprises:
a plurality of the second-conductive type CCD channel regions made of a plurality of second-conductive type impurity regions each extending in a column direction into at least a region located between adjacent columns of the holes formed in the first-conductive type planar semiconductor layer; and
a plurality of the first-conductive type high-concentration impurity-doped element isolation regions each arranged to prevent contact between adjacent second-conductive type CCD channel regions.
4. The solid-state image pickup device as defined in claim 3 , comprising a plurality of the transfer electrodes each formed to extend in a row direction into a region located between adjacent rows of the holes formed in the first-conductive type planar semiconductor layer, and each arranged along an associated second-conductive type CCD channel region so as to have a given space distance therebetween to transfer therethrough signal charges generated in an associated solid-state image pickup element.