Fig. 1.
N buried layer structure of PPD.
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| Citation: |
Feng Li, Ruishuo Wang, Liqiang Han, Jiangtao Xu. Design of CMOS active pixels based on finger-shaped PPD[J]. Journal of Semiconductors, 2020, 41(10): 102301. doi: 10.1088/1674-4926/41/10/102301
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F Li, R S Wang, L Q Han, J T Xu, Design of CMOS active pixels based on finger-shaped PPD[J]. J. Semicond., 2020, 41(10): 102301. doi: 10.1088/1674-4926/41/10/102301.
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Design of CMOS active pixels based on finger-shaped PPD
DOI: 10.1088/1674-4926/41/10/102301
More Information
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Abstract
To improve the full-well capacity and linear dynamic range of CMOS image sensor, a special finger-shaped pinned photodiode (PPD) is designed. In terms of process, the first N-type ion implantation of the PPD N buried layer is extended under the transfer gate, thereby increasing the PPD capacitance. Based on TCAD simulation, the width and spacing of PPD were precisely adjusted. A high full-well capacity pixel design with a pixel size of 6 × 6 μm2 is realized based on the 0.18 μm CMOS process. The simulation results indicate that the pixel with the above structure and process has a depletion depth of 2.8 μm and a charge transfer efficiency of 100%. The measurement results of the test chip show that the full-well capacity can reach 68650e–. Compared with the conventional structure, the proposed PPD structure can effectively improve the full well capacity of the pixel.-
Keywords:
- CMOS active pixel,
- full well capacity,
- full depletion
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References
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