Low-temperature characterization of buried-channel NMOST

Wilcox, R.; Chang, Jane P.; Viswanathan, C.R.

doi:10.1109/16.30957

Cited by 31 publications

(21 citation statements)

References 16 publications

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“…In this mode, a part or the whole of the channel could be in accumulation, resulting in current flow at the Si-SiO 2 interface and increased 1/ f noise [7]. If the gate is biased sufficiently negative with respect to the substrate, an inversion layer under the gate begins to appear.…”

Section: A Principles Of Operationmentioning

confidence: 98%

“…Another advantage is the increased carrier mobility, because carriers flow through semiconductor with nearly bulk properties. Typically bulk mobility is a factor of two higher than the surface mobility [7], [8], which is favorable for achieving higher gate transconductance g m and lower thermal noise than SC devices. However, the additional separation between the gate and the channel reduces the effective gate capacitance, which goes against the effects from the increased carrier mobility.…”

Section: A Principles Of Operationmentioning

confidence: 99%

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Performance of Deep-Depletion Buried-Channel $n$-MOSFETs for CMOS Image Sensors

Stefanov

Zhang

Damerell

et al. 2013

IEEE Trans. Electron Devices

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Buried-channel (BC) MOSFETs are known to have better noise performance than their surface-channel (SC) counterparts when used as a source follower in modern chargecoupled devices (CCDs). CMOS image sensors are finding increasing applications and compete with CCDs in highperformance imaging, but BC transistors are rarely used in CMOS. As a part of the development of charge storage using CCDs in CMOS, we designed and manufactured deep-depletion BC n-type MOSFETs in 0.18-µm CMOS image sensor process. The BC transistors are designed in a way similar to the source followers in a typical BC CCD, and feature deep n-channel implant and threshold voltage exceeding −2.5 V. In this paper, we report the results from their characterization and compare them with normal enhancement mode and "zero-threshold" SC devices. In addition to the detailed current-voltage and noise measurements, 2-D semiconductor device simulation results are presented to illustrate and understand the different conditions affecting the channel conduction and the noise performance of the BC transistors. We show that under optimal bias conditions the noise performance of the BC transistors can be superior despite their lower gain as in-pixel source followers.Index Terms-Buried-channel (BC) MOSFET, CMOS image sensors, semiconductor device noise.

show abstract

Section: A Principles Of Operationmentioning

confidence: 98%

Section: A Principles Of Operationmentioning

confidence: 99%

Performance of Deep-Depletion Buried-Channel $n$-MOSFETs for CMOS Image Sensors

Stefanov

Zhang

Damerell

et al. 2013

IEEE Trans. Electron Devices

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show abstract

“…Another advantage is the increased carrier mobility, because carriers flow through semiconductor with nearly bulk properties. Typically bulk mobility is a factor of two higher than the surface mobility 7,8 , which is favorable for achieving higher gate transconductance g m and lower thermal noise than SC devices. However, the additional separation between the gate and the channel reduces the effective gate capacitance C ox , which goes against the effects from the increased carrier mobility.…”

Section: Operation Of the Bc Mosfetmentioning

confidence: 99%

“…As the gate bias becomes more negative, the expanding inversion layer begins to shield the channel from further changes of the gate potential, leading to a marked decrease in the gate transconductance g m and increased generationrecombination noise [7][8][9][10] . For optimal noise performance BC transistors should be operated with the interface in depletion, avoiding either accumulation or inversion under the gate.…”

Section: Operation Of the Bc Mosfetmentioning

confidence: 99%

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Performance of buried channeln-type MOSFETs in 0.18-μm CMOS image sensor process

et al. 2013

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Buried channel (BC) MOSFETs are known to have better noise performance than surface channel (SC) MOSFETs when used as source followers in modern Charge Coupled Devices (CCD). CMOS image sensors find increasing range of applications and compete with CCDs in high performance imaging, however BC transistors are rarely used in CMOS. As a part of the development of charge storage using BC CCDs in CMOS, we designed and manufactured deep depletion BC n-type MOSFETs in 0.18 µm CMOS image sensor process. The transistors are designed in a way similar to the source followers in a typical BC CCD. In this paper we report the results from their characterization and compare with enhancement mode and "zero-threshold" SC devices. In addition to the detailed current-voltage and noise measurements, semiconductor device simulation results are presented to illustrate and understand the different conditions affecting the channel conduction and the noise performance of the BC transistors at low operating voltages. We show that the biasing of the BC transistors has to be carefully adjusted for optimal operation, and that their noise performance at the right operating conditions can be superior to SC devices, despite their lower gain as in-pixel source followers.

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1/F Noise in Mosfets

Haartman

Östling

2007

Low-Frequency Noise in Advanced Mos Devices

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Low-temperature characterization of buried-channel NMOST

Cited by 31 publications

References 16 publications

Performance of Deep-Depletion Buried-Channel $n$-MOSFETs for CMOS Image Sensors

Performance of Deep-Depletion Buried-Channel $n$-MOSFETs for CMOS Image Sensors

Performance of buried channeln-type MOSFETs in 0.18-μm CMOS image sensor process

1/F Noise in Mosfets

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