A CPD image sensor with buried-channel priming couplers

A 398 (H) × 496 (V)-element CPD image sensor with buried-channel charge-priming-transfer (CPT) couplers for ⅔-in format has been developed. The buried-channel CPT structures by use of the external bias change has been adopted based on the theoretical consideration to suppress random noise and to improve vertical transfer efficiency for small signal charge. The vertical transfer efficiency even for small signal charges was improved up from 70 to 95 percent or more by use of the external bias charge in addition to priming charge. It was found that total random noise in the new image sensor corresponds to ∼ 400 electrons, which is about half of that in a conventional CPD image sensor with surface-channel CPT couplers.