Design of prototype high speed CMOS image sensors

Abstract

Large size photodiode used in high speed CMOS image sensor pixel suffers from slow signal charges transfer speed and large image lag. To solve these problems, in this paper, we present a new device structure for high speed CMOS image sensor pixel with lateral graded-doping profile pinned photodiode and non-uniform doped channel transfer gate. Theory analysis and TCAD simulation results indicate that the proposed pixel can increase the signal charges transfer speed and reduce the image lag effectively. The measurement results show that, the proposed pixel is able to achieve 40ns readout time and 0.44% image lag. Compare to conventional pixels, 64 times higher readout speed enhancement and five times lower image lag were achieved.