US 2011/0210383 A1Published application

Imaging device

AssigneeFujitsu Semiconductor Limited

InventorsTadao INOUE, Katsuyoshi YAMAMOTO, Hiroshi KOBAYASHI

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Abstract

First diffusion region constituting a photodiode in each pixel stores carriers generated according to incident light. Second diffusion region is formed at a surface of the first diffusion region to cover a peripheral part of the first diffusion region. In the peripheral part of the first diffusion region, crystal defects tend to occur by a process of forming an isolation region and a gate electrode, so that dark current noise tends to occur. The second diffusion region functioning as a protection layer prevents crystal defects in a manufacturing process. The second diffusion region isn't formed on a center of the surface of the first diffusion region where crystal defects don't tend to occur. In the first diffusion region where the second diffusion region isn't formed, the thickness of a depletion layer increases, which improves light detection sensitivity. This improves detection sensitivity of the photodiode without increasing the dark current noise.

Claims12

Dependent claims

An imaging device, comprising a plurality of pixels each including a photodiode, wherein

said pixels receive either light incident via a first filter which selectively transmits relatively short-wavelength light or light incident via a second filter which selectively transmits relatively long-wavelength light,
each pixel receiving said relatively short-wavelength light includes:
a first diffusion region of a first conductive type which constitutes a storing part of optical carriers in said photodiode;
a transfer transistor which uses said first diffusion region as a source electrode, whose gate electrode is formed in a position adjacent to said first diffusion region via an insulating film, and which transfers the optical carriers stored in said photodiode to a drain electrode;
and
a second diffusion region of a second conductive type which is formed at a surface of said first diffusion region to cover a peripheral part of said first diffusion region and has a polarity opposite to that of the first conductive type, and
each pixel receiving said relatively long-wavelength light comprises:
a first diffusion region of the first conductive type which constitutes a storing part of optical carriers in said photodiode;
a transfer transistor which uses said first diffusion region as a source electrode, whose gate electrode is formed in a position adjacent to said first diffusion region via an insulating film, and which transfers the optical carriers stored in said photodiode to a drain electrode;
and
a second diffusion region of the second conductive type which is formed to cover an entire surface of said first diffusion region and has a polarity opposite to that of the first conductive type.

8 more elements

An imaging device, comprising a plurality of pixels each including a photodiode, wherein

said pixels receive either light incident via a first filter which selectively transmits relatively short-wavelength light or light incident via a second filter which selectively transmits relatively long-wavelength light,
each pixel receiving said relatively short-wavelength light includes:
a first diffusion region of a first conductive type which constitutes a storing part of optical carriers in said photodiode;
a transfer transistor which uses said first diffusion region as a source electrode, whose gate electrode is formed in a position adjacent to said first diffusion region via an insulating film, and which transfers the optical carriers stored in said photodiode to a drain electrode;
and
a second diffusion region of a second conductive type which is formed at a surface of said first diffusion region to cover a partial peripheral part other than a portion adjacent to said gate electrode of a peripheral part of said first diffusion region and has a polarity opposite to that of the first conductive type, and
each pixel receiving said relatively long-wavelength light comprises:
a first diffusion region of the first conductive type which constitutes a storing part of optical carriers in said photodiode;
a transfer transistor which uses said first diffusion region as a source electrode, whose gate electrode is formed in a position adjacent to said first diffusion region via an insulating film, and which transfers the optical carriers stored in said photodiode to a drain electrode;
and
a second diffusion region of the second conductive type which is formed to cover an entire surface of said first diffusion region and has a polarity opposite to that of the first conductive type.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 13/104,673Filed 10 May 2011
Priority: 28 Mar 2005
Published: 1 Sep 2011
Term ends: Not estimatedThe source records don’t support an estimate.

Classification15 codes

H10F 39/802
Constructional details of image sensors: geometry or disposition of elements in pixels, e.g. address-lines or gate electrodes
H04N 25/00
Circuitry of solid-state image sensors [ssis]
H04N 25/63
Noise processing, e.g. detecting, correcting, reducing or removing noise: applied to dark current
H04N 25/68
Noise processing, e.g. detecting, correcting, reducing or removing noise: applied to defects

Family

Application11/861,691Division · filed 26 Sep 2007
Application13/104,673Division
Application11/861,691Continuation
US 2008/0029788 A1Published application
US 7,964,902 B2Related patent
US 8,110,860 B2Related patent
US 2011/0210383 A1This patent

From the US filing history. Foreign family members aren’t listed.