Extraction and Estimation of Pinned Photodiode Capacitance in CMOS Image Sensors

Chao, Calvin Yi‐Ping; Chen, Yi-Che; Chou, Kevin; Sze, Jhy-Jyi; Hsueh, Fu-Lung; Wuu, Shou-Gwo

doi:10.1109/jeds.2014.2318060

Cited by 23 publications

(8 citation statements)

References 8 publications

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“…PPDs have been extensively studied in order to understand all the transfer mechanisms between the photodiode and the floating diffusion, the PPD key feature parameters and its access [5], [6], [7]. Although many dark current measurements of pinned photodiodes have been presented, to our knowledge, no study explains and demonstrates the possibility of dark current reduction by sharing mechanisms between adjacent PN junctions.…”

Section: Introductionmentioning

confidence: 99%

Dark Current Sharing and Cancellation Mechanisms in CMOS Image Sensors Analyzed by TCAD Simulations

Marcelot

Goiffon

Rizzolo

et al. 2017

IEEE Trans. Electron Devices

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TCAD simulations are conducted on a 4T PPD pixel, on a conventional gated photodiode, and finally on a radiation hardened pixel. Simulations consist in demonstrating that it is possible to reduce the dark current due to interface states brought by the adjacent gate, by means of a sharing mechanism between the photodiode and the drain. The sharing mechanism is activated and controlled by polarizing the adjacent gate at a positive off voltage, and consequently the dark current is reduced and not compensated. The drawback of the dark current reduction is a reduction of the full well capacity of the photodiode, which is not a problem when the pixel saturation is limited by the readout chain. Some measurement performed on pixel arrays confirm the TCAD results.

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Section: Introductionmentioning

confidence: 99%

Dark Current Sharing and Cancellation Mechanisms in CMOS Image Sensors Analyzed by TCAD Simulations

Marcelot

Goiffon

Rizzolo

et al. 2017

IEEE Trans. Electron Devices

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“…This model analyzed the influence of doping concentration and implant energy of the donor and acceptor of PD. Furthermore, dynamic capacitance models during the charge accumulated phase were discussed in [7,8], and a method to extract the PD capacitance by the FWC characteristic curve is proposed in [9].…”

Section: Introductionmentioning

confidence: 99%

Analytical Modeling of Exposure Process in Pinned Photodiode CMOS Image Sensors

Gao

Gong

Gao

et al. 2020

IEEE J. Electron Devices Soc.

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The output features of pixels in CMOS image sensors (CISs) are influenced by different exposure conditions. This paper presents an analytical model to describe the output characteristics of the exposure process in pinned photodiode (PPD) CMOS image sensors with the accumulation of three charge sources: photogenerated charge, p-n junction-generated charge, and emission charge. In the proposed model, the difference between the time-based and light intensity-based photo response process is illustrated. The model also reveals the relationship between photodiode potential and light intensity at different exposure values. At the low exposure values, the PD potential increases with light intensity, and a contrary trend is observed at the high exposure values. This concludes that a larger linear output range can be obtained in high light intensity conditions. Furthermore, the improved model provides development analysis in terms of light intensity influence for long exposure time noise. The models were verified with technology computer-aided design simulation and the test devices were fabricated using a 0.18-μm CIS process. The model demonstrates good consistency with simulation and measured results.

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“…P INNED Photodiode (PPD) CMOS image sensors (CIS) are widely used in many products ranging from smartphones to scientific applications. Due to the continual technology improvement and to a better understanding of the device operation [1], [2], PPDs achieve now very high performances and overcome Charge Coupled Devices (CCD) in more and more challenging applications such as astronomy or earth observation. Compared to the simpler 3T pixels based on a conventional photodiode [3], PPD pixels include at least one more transistor which allows the charge transfer from a buried photodiode isolated from the surface oxide by the pinned P+ layer, to the floating node [4].…”

Section: Introductionmentioning

confidence: 99%

Exploration of Pinned Photodiode Radiation Hardening Solutions Through TCAD Simulations

Marcelot

Goiffon

Magnan

2019

IEEE Trans. Electron Devices

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The use of pinned photodiode (PPD) based CMOS image sensors in harsh radiation environment (such as space) is limited by their tolerance to ionizing radiation. Technology computer aided design (TCAD) simulations are performed to reproduce the radiation induced defect and therefore the dark current increase in pinned photodiode pixels up to 1 kGy (i.e. 100 krad) of total ionizing dose (TID). To do so, the TCAD models are calibrated with measurements performed on irradiated pixels. Then, the influence on the PPD radiation hardness of various manufacturing process and pixel design modifications is explored. This works shows that the proposed modification can improve the radiation hardness of pinned photodiode CMOS image sensors against ionizing.

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Extraction and Estimation of Pinned Photodiode Capacitance in CMOS Image Sensors

Cited by 23 publications

References 8 publications

Dark Current Sharing and Cancellation Mechanisms in CMOS Image Sensors Analyzed by TCAD Simulations

Dark Current Sharing and Cancellation Mechanisms in CMOS Image Sensors Analyzed by TCAD Simulations

Analytical Modeling of Exposure Process in Pinned Photodiode CMOS Image Sensors

Exploration of Pinned Photodiode Radiation Hardening Solutions Through TCAD Simulations

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