An ultra-low dark current CMOS image sensor cell using n+ ring reset

We present in this letter for the first time a new CMOS image sensor cell using n+-ring-reset structure, which can isolate the photon-sensing area from the defective field oxide edge. The experimental results demonstrate that the severe dark current degradation of the conventional CMOS active pixel image sensor fabricated by a standard CMOS logic process is significantly alleviated. Through optimizing the layout arrangement, as high as 45 percent fill factor can be obtained. The dynamic range of this new cell can thus be improved by more than 10 compared to a conventional cell. (Author)