Trench photosensor for a CMOS imager
First Claim
Patent Images
1. A photosensor for use in an imaging device, said photosensor comprising:
- a doped layer of a first conductivity type formed in a substrate;
a trench formed in said doped layer;
a doped region of a second conductivity type formed at the sidewalls and bottom of said trench; and
an insulating layer formed over said doped region.
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Abstract
A trench photosensor for use in a CMOS imager having an improved charge capacity. The trench photosensor may be either a photogate or photodiode structure. The trench shape of the photosensor provides the photosensitive element with an increased surface area compared to a flat photosensor occupying a comparable area on a substrate. The trench photosensor also exhibits a higher charge capacity, improved dynamic range, and a better signal-to-noise ratio. Also disclosed are processes for forming the trench photosensor.
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Citations
84 Claims
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1. A photosensor for use in an imaging device, said photosensor comprising:
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a doped layer of a first conductivity type formed in a substrate;
a trench formed in said doped layer;
a doped region of a second conductivity type formed at the sidewalls and bottom of said trench; and
an insulating layer formed over said doped region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A photogate sensor for use in an imaging device, said photogate sensor comprising:
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a doped layer of a first conductivity type formed in a substrate;
a trench formed in said doped layer;
a doped region of a second conductivity type formed at the sidewalls and bottom of said trench;
an insulating layer formed on substantially all of an upper surface of said doped region; and
a light radiation-transparent electrode formed on substantially all of an upper surface of said insulating layer for gating the collection of charges in said doped region. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42)
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43. A photodiode sensor for use in an imaging device, said photodiode sensor comprising:
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a doped layer of a first conductivity type formed in a substrate;
a trench formed in said doped layer, wherein the trench has a depth within the range of approximately 0.05 to 10 μ
m; and
a doped region of a second conductivity type formed at the sidewalls and bottom of said trench. - View Dependent Claims (44, 45, 46, 47, 48)
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49. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a doped layer of a first conductivity type formed in a substrate;
a trench formed in said doped layer;
a first doped region of a second conductivity type formed at the sidewalls and bottom of said trench;
an insulating layer formed over said first doped region;
a second doped region of a second conductivity type formed in said doped layer and positioned to receive charges from said first doped region of said trench; and
a reset transistor formed at the doped layer for periodically resetting a charge level of said second doped region, said second doped region being the source of said reset transistor. - View Dependent Claims (50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68)
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69. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a doped layer of a first conductivity type formed in a substrate;
a trench formed in said doped layer;
a photodiode formed in said trench, wherein said photodiode comprises a first doped region of a second conductivity type formed at the sidewalls and bottom of said trench, and an insulating layer formed on an upper surface of said first doped region;
a second doped region of a second conductivity type formed in said doped layer and positioned to receive charges from said first doped region of said trench; and
a reset transistor formed at the doped layer for periodically resetting a charge level of said second doped region, said second doped region being the source of said reset transistor.
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70. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a doped layer of a first conductivity type formed in a substrate;
a trench formed in said doped layer;
a photogate formed in said trench, wherein said photogate comprises a first doped region of a second conductivity type formed at the sidewalls and bottom of said trench, a conductive layer formed on substantially all of an upper surface of said first doped region for gating the collection of charges in said first doped region, and an insulating layer formed between said first doped region and said conductive layer;
a second doped region of a second conductivity type formed in said doped layer and positioned to receive charges from said first doped region of said trench; and
a reset transistor formed at the doped layer for periodically resetting a charge level of said second doped region, said second doped region being the source of said reset transistor.
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71. A pixel sensor cell for use in an imaging device, said pixel sensor cell comprising:
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a trench photosensor formed in a doped layer of a first conductivity type of a substrate;
a reset transistor formed in said doped layer;
a floating diffusion region of a second conductivity type formed in said doped layer between the trench photosensor and the reset transistor for receiving charges from said trench photosensor, said reset transistor operating to periodically reset a charge level of said floating diffusion region; and
an output transistor having a gate electrically connected to the floating diffusion region. - View Dependent Claims (72, 73, 74, 75, 76)
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77. A CMOS imager comprising:
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a substrate having a doped layer of a first conductivity type;
an array of pixel sensor cells formed in said doped layer, wherein each pixel sensor cell has a trench photosensor; and
signal processing circuitry electrically connected to receive and process output signals from said array. - View Dependent Claims (78, 79, 80, 81, 82)
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83. An integrated circuit imager comprising:
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an array of pixel sensor cells formed in a substrate, wherein each pixel sensor cell has a trench photosensor;
signal processing circuitry formed in said substrate and electrically connected to the array for receiving and processing signals representing an image output by the array and for providing output data representing said image; and
a processor for receiving and processing data representing said image.
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84. An integrated circuit imager comprising:
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a CMOS imager, said CMOS imager comprising an array of pixel sensor cells formed in a doped layer on a substrate, wherein each pixel sensor cell has a trench photosensor with a first doped region formed therein, each of said cells having a respective second doped region for receiving and outputting image charge received from said first doped region, and signal processing circuitry formed in said substrate and electrically connected to the array for receiving and processing signals representing an image output by the array and for providing output data representing said image; and
a processor for receiving and processing data representing said image.
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Specification