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US 6,806,522 B2Granted
CMOS image sensor and manufacturing method for the same
AssigneeNEC Electronics Corporation
InventorHiroaki Ohkubo
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Abstract
The invention provides a CMOS image sensor that can decrease the influence of the noise charge on the OB cells that determine the darkness level and can prevent the deterioration of the image quality. A region that absorbs the noise charge in a substrate is formed at the periphery of the cell array portion. As in the photodiode, a PN junction is formed in the noise charge absorption region, and one end thereof is connected to a power source voltage. This noise charge absorption region is formed between the cell array portion and the peripheral circuit portion.
Claims22
A Complementary Metal Oxide Semiconductor (CMOS) image sensor having a cell array portion in which single cells are disposed in an array and a peripheral circuit portion that controls said cell array, said CMOS image sensor comprising:
- a peripheral circuit portion comprising a plurality of circuits formed on a silicon substrate and disposed on a periphery of said cell array portion;
- p1 a plurality of single cells serving as photosensors in said cell array, each said cell including a buried photodiode structure comprising:
- a first cell diffusion region formed on said silicon substrate, said first cell diffusion region having a same conductivity type as a conductivity type of said silicon substrate;
- a second cell diffusion region directly below said first cell diffusion region, said second cell diffusion region having a conductivity type different than a conductivity type of said silicon substrate;
- a third cell diffusion region underlying said second cell diffusion region, said third cell diffusion region comprising a deep well region having a same conductivity type as said silicon substrate;
- and
- a fourth cell diffusion region contacting said third cell diffusion region and serving as a sidewall well region that surrounds said second cell diffusion region, said fourth cell diffusion region having a same conductivity type as said silicon substrate;
- and
- a noise charge absorption region provided on the periphery of said cell or said cell array portion, said noise charge absorption region including a diffusion layer formed on said silicon substrate,
- wherein said diffusion layer is connected to a constant potential, said diffusion layer having a conductivity type different than a conductivity type of said silicon substrate, and
- wherein said noise charge absorption region collects stray charges generated by said peripheral circuit portion.
8 more elements
A Complementary Metal Oxide Semiconductor (CMOS) image sensor, comprising:
- a cell array portion comprising a photodiode cell array formed on a semiconductor substrate, each said photodiode cell comprising:
- a first cell diffusion region formed on said semiconductor substrate, said first cell diffusion region having a first conductivity type;
- a second cell diffusion region directly below said first cell diffusion region, said second cell diffusion region having a second conductivity type different from said first conductivity type;
- a third cell diffusion region underlying said second cell diffusion region, said third cell diffusion region comprising a deep well region having said first conductivity type;
- and
- a fourth cell diffusion region contacting said third cell diffusion region and serving as a sidewall well region that surrounds said second cell diffusion region, said fourth cell diffusion region having said first conductivity type;
- a peripheral circuit portion comprising a plurality of circuits formed on the semiconductor substrate and disposed on the periphery of said cell array portion;
- and
- a noise charge absorption region, comprising a diffusion layer formed on the semiconductor substrate and disposed between said cell array portion and said peripheral circuit portion,
- wherein said noise charge absorption region collects stray charges generated by said peripheral circuit portion.
7 more elements
A Complementary Metal Oxide Semiconductor (CMOS) image sensor, comprising:
- a plurality of optical black photodiode cells disposed in a cell array formed on a semiconductor substrate, each said optical black photodiode cell comprising:
- a first cell diffusion region formed on said semiconductor substrate, said first cell diffusion region having a first conductivity type;
- a second cell diffusion region directly below said first cell diffusion region, said second cell diffusion region having a second conductivity type different from said first conductivity type;
- a third cell diffusion region underlying said second cell diffusion region, said third cell diffusion region comprising a deep well region having said first conductivity type;
- and
- a fourth cell diffusion region contacting said third cell diffusion region and serving as a sidewall well region that surrounds said second cell diffusion region, said fourth cell diffusion region having said first conductivity type;
- a peripheral circuit portion comprising a circuit that controls said cell array;
- and
- a noise charge absorption region comprising a diffusion layer that is provided on the periphery of said cell array,
- wherein said diffusion layer is connected to a constant potential, and
- wherein said noise charge absorption region collects stray charges generated by said peripheral circuit portion.
8 more elements
Dependencies are inferred from the claim text.