A LOW DARK CURRENT CCD LINEAR IMAGE SENSOR

A low dark current CCD linear image sensor with pixels consisting of a photodiode and a storage area has been developed. In order to suppres s the dark current, the wafer process has been improved. An impurity p rofile of a photodiode was modified to minimize depletion width, which was monitored by the photodiode potential. Surface states under the s torage gate were decreased by hydrogen annealing with plasma-deposited silicon nitride as an inter metal dielectric film. As the isolation d ose decreased, the dark current both in the photodiode and in the stor age region were effectively suppressed. Finally, low dark currents of 5 pA/cm(2) at photodiode and 120 pA/cm(2) at storage area were obtaine d.