Back to results
US 2006/0038207 A1Published application
Wide dynamic range sensor having a pinned diode with multiple pinned voltages
AssigneeMicron Technology, Inc.
InventorsSungkwon Hong, Alex Krymski
Life of this patent
Estimating the term…
Abstract
A pixel cell has controlled photosensor anti-blooming leakage by having dual pinned voltage regions, one of which is used to set the anti-blooming characteristics of the photosensor. Additional exemplary embodiments also employ an anti-blooming transistor in conjunction with the dual pinned photosensor. Other exemplary embodiments provide a pixel with two pinned voltage regions and two anti-blooming transistors. Methods of fabricating the exemplary pixel cells are also disclosed.
Claims76
A photosensor comprising:
- a first charge accumulation region formed in a substrate and being doped to a first conductivity type and a first concentration;
- a second charge accumulation region formed in said substrate and located adjacent said first accumulation region and being doped to said first conductivity type and a second concentration, wherein said first concentration is greater than said second concentration creating a barrier to charge flow from said first charge accumulation region.
A pinned photodiode comprising:
- at least first and second doped charge accumulation regions formed in a substrate and being capable of generating charge in response to light, said first charge accumulation region having a first pinned voltage and said second charge accumulation region having a second pinned voltage,
- wherein said second charge accumulation region is formed to receive charge from said first accumulation region once charge in said first accumulation region exceeds a threshold amount.
A pixel cell comprising:
- a photosensor comprising first and second charge accumulation regions, said accumulation regions having respective first and second different concentrations of dopant ions of a first conductivity type;
- a first anti-blooming transistor electrically connected to said photosensor for draining charges away from said photosensor;
- and
- a doped region adjacent to said first anti-blooming transistor for receiving charges drained from said photosensor.
1 more element
A pixel cell comprising:
- a pinned photodiode formed in a semiconductor substrate, said photodiode comprising first and second charge accumulation regions for accumulating photo-generated charges during an integration period, said first accumulation region having a first pinned voltage, said second accumulation region having a second pinned voltage, wherein said first pinned voltage is greater than said second pinned voltage, such that charges accumulated in said first accumulation region flow to said second accumulation region once a barrier set by the different pinned voltages is overcome.
An array of pixel sensor cells comprising:
- a plurality of pixel sensor cells formed in a substrate and arranged into rows and columns, a plurality of said pixel sensor cells, each said cell comprising:
- a photosensor for generating charge during an integration period, said photosensor comprising first and second doped, accumulation regions located beneath the surface of the substrate and having first and second pinned voltages respectively, wherein said first pinned voltage is greater than said second pinned voltage and said second accumulation region is formed to receive charges from said first accumulation region.
An imager system, comprising:
- a processor;
- and
- an imaging device electrically coupled to said processor, said imaging device comprising a pixel array, at least one pixel cell of said array comprising:
- a photosensor for accumulating charge during an integration period, said photosensor comprising a first accumulation region having a first pinned voltage and a second accumulation region adjacent said first accumulation region and having a second pinned voltage, wherein said accumulated charge flows from said first accumulation region to said second accumulation region during said integration period once a barrier set by said pinned voltage is overcome;
- and
- a transistor on a first side of said photosensor for draining charge away from said second accumulation region.
3 more elements
An imager system, comprising:
- a processor;
- and
- an imaging device electrically coupled to said processor, said imaging device comprising an array of pixels, each pixel comprising:
- a pinned photodiode for producing photo-generated charges during an integration period, said pinned photodiode comprising a first accumulation region having a first dopant concentration of a first type conductivity and a second accumulation region having a second dopant concentration of said first type conductivity, wherein said first concentration is greater than said second concentration;
- a transfer gate formed on a first side of said pinned photodiode;
- and
- a drain region formed in said substrate on one side of said photodiode.
4 more elements
A method of forming a photosensor, said method comprising:
- forming a first doped region in a substrate, the first doped region having a first pinned voltage and being doped to a first conductivity type;
- and
- forming a second doped region adjacent said first doped region, said second doped region being doped to said first conductivity type and having a second pinned voltage that is less than said first pinned voltage.
A method of forming a pixel cell, said method comprising:
- forming a photosensor in a substrate having a first conductivity type, the photosensor comprising first and second charge accumulation regions having first and second pinned voltages respectively and being located beneath the surface of the substrate;
- and
- forming an anti-blooming transistor on a first side of the photosensor for draining charges away from the photosensor during the integration period.
A method of operating a wide dynamic range pixel cell, the method comprising:
- resetting a photosensor to remove all charge from the photosensor, the photosensor comprising first and second charge accumulation regions having respective first and second pinned voltages;
- exposing the photosensor to light during an integration period, the photosensor capable of converting the light into charges;
- draining said charges from said first accumulation region into said second accumulation region;
- and
- performing a readout of the charges generated by the photosensor during the integration period.
2 more elements
Dependencies are inferred from the claim text.