Long Exposure Time Noise in Pinned Photodiode CMOS Image Sensors

This letter focuses on a new noise source within a pinned photodiode in complimentarymetal-oxide-semiconductor(CMOS) image sensors. The noise originates from the feedforward effect, which is related to the barrier height under the transfer gate during the exposure phase. TCAD simulations using the Monte Carlo method show that the barrier height varies with CMOS process fluctuations even for the same pixel design and applied voltage. Furthermore, a model extending our previous work is proposed. The model results indicate that a larger barrier height and shorter exposure time improve the noise performance. The same conclusion can also be obtained from the measurements of a prototype image sensor that can adjust the pixel implants.

这封信重点关注互补金属氧化物半导体（CMOS）图像传感器中钉扎光电二极管内的一种新噪声源。该噪声源于前馈效应，它与曝光阶段转移栅下方的势垒高度有关。采用蒙特卡罗方法的TCAD模拟表明，即使对于相同的像素设计和施加电压，势垒高度也会随着CMOS工艺波动而变化。此外，提出了一个扩展我们先前工作的模型。模型结果表明，较大的势垒高度和较短的曝光时间可改善噪声性能。从一个可调整像素注入的原型图像传感器的测量中也能得出相同结论。