| 摘要 |
PROBLEM TO BE SOLVED: To stably form an overflow barrier that determines a predetermined amount of charge accumulated in a photodiode and flowing out into a memory part.SOLUTION: In a unit pixel 120A, a gate electrode 122A made of P-type poly-Si and a gate electrode 122B made of N-type poly-Si are arranged as gate electrodes with different work functions, the gate electrodes being arranged above a memory part 123 and an overflow path 130. An offset between the gate electrodes 122A and 122B depresses the potential of a P-type well layer 132 in the boundary part between a photodiode 121 and the memory part 123 to form the overflow path 130. Thereby, an overflow barrier can be formed stably. The unit pixel can be applied, for example, to a CMOS image sensor having a pixel structure in which an overflow path for transferring a charge from a photoelectric conversion element to the charge retention region is formed. |
