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

作　　者：李毅强 李斌桥 徐江涛 高志远 徐超 孙羽 

机构地区：[1]School of Electronic Information Engineering,Tianjin University

出　　处：《Journal of Semiconductors》2012年第12期31-36,共6页半导体学报（英文版）

基　　金：Project supported by National Natural Science Foundation of China(Nos.61036004,61076024)

摘　　要：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 chan- nel 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 1/10^4 to 1/10^7, and the transfer time is reduced from 500 to 110 ns. This means the charge transfer efficiency is improved.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 chan- nel 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 1/10^4 to 1/10^7, and the transfer time is reduced from 500 to 110 ns. This means the charge transfer efficiency is improved.

关 键 词：CMOS image sensor charge transfer efficiency non-uniform doped transfer transistor channel potential barrier potential pocket 

分 类 号：TN312[电子电信—物理电子学]