优化传输栅下电势分布改善四管像素的电荷转移效率

提出了一种通过优化传输栅下沿电荷转移路径的电势分布来提高电荷转移效率的方法。通过使用非均匀掺杂传输管沟道，形成了传输管沟道内部的电势分布梯度。通过对R1区与传输栅的交叠长度，R1区的掺杂剂量，防穿通注入（APT）与传输栅交叠长度的调整，减小了传输管沟道与箝位光电二极管（PPD）连接区域的电子势垒与电子势阱，增强了二者的电势连接。仿真结果显示，剩余电荷占总电荷的比例由1/104减小至1/107，转移时间由500 ns缩短为110 ns。这意味电荷转移效率得到了提高。

Charge transfer efficiency improvement of a 4-T pixel by the optimization of electrical potential distribution under the transfer gate

The charge transfer efficiency improvement method is introduced by optimizing the electrical potential distribution under the transfer gate along the charge transfer path. A non-uniform doped transfer transistor channel is introduced to provide an ascending electrical potential gradient in the transfer transistor channel. With the adjustments to the overlap length between the R1 region and the transfer gate, the doping dose of the R1 region, and the overlap length between the anti-punch-through (APT) implantations and transfer gate, the potential barrier and potential pocket in the connecting region of transfer transistor channel and the pinned photodiode (PPD) are reduced to improve the electrical potential connection. The simulation results show that the percentage of residual charges to total charges drops from 1/10⁴ to 1/10⁷, and the transfer time is reduced from 500 to 110 ns. This means the charge transfer efficiency is improved.