Methods and devices for improved charge management for three-dimensional and color sensing
First Claim
1. A CMOS-implementable semiconductor photodetector useable in a system that illuminates a target with optical energy having a modulated periodic waveform that includes a high frequency component, generated in response to signal provided by a clock generator, and that detects a fraction of said optical energy reflected by said target with at least one said semiconductor photodetector, said photodetector comprising:
- a semiconductor substrate having a surface upon which said incoming optical energy can impinge onto an optical energy sensitive region, said surface defining an x-direction and a y-direction;
at least a first elongate-shaped polysilicon gate disposed on said surface parallel to said y-direction, said first gate coupleable to a first bias clock signal, synchronously generated by said clock generator, that is high during a first bias regime to detect and collect charge generated by at least a fraction of said incoming optical energy;
a first source region formed in said substrate adjacent a distal end of said first gate;
at least a second elongate-shaped polysilicon gate disposed on said surface parallel to said first elongate-shaped gate and spaced-apart in said x-direction a distance substantially shorter than a length of either said gate, said second gate coupleable to a second bias clock signal synchronously generated by said clock generator;
a second source region formed in said substrate adjacent a distal end of said second gate;
wherein responsive to said first bias clock signal and said second bias clock signal, photoelectic charge generated in said substrate is moved in said x direction to become trapped beneath an elongate-shaped gate and is then moved in said y-direction to an adjacent source region for collection, charge movement in said y-direction being slower than charge movement in said x-direction, wherein modulation contrast of said photodetector is enhanced.
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Abstract
TOF and color sensing detector structures have x-axis spaced-apart y-axis extending finger-shaped gate structures with adjacent source collection regions. X-dimension structures are smaller than y-dimension structure and govern performance, characterized by high x-axis electric fields and rapid charge movement, contrasted with lower y-axis electric fields and slower charge movement. Preferably a potential barrier is implanted between adjacent gates and a bias gate is formed intermediate a gate and associated source region. Resultant detector structures can be operated at the more extreme gate voltages that are desirable for high performance.
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Citations
23 Claims
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1. A CMOS-implementable semiconductor photodetector useable in a system that illuminates a target with optical energy having a modulated periodic waveform that includes a high frequency component, generated in response to signal provided by a clock generator, and that detects a fraction of said optical energy reflected by said target with at least one said semiconductor photodetector, said photodetector comprising:
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a semiconductor substrate having a surface upon which said incoming optical energy can impinge onto an optical energy sensitive region, said surface defining an x-direction and a y-direction; at least a first elongate-shaped polysilicon gate disposed on said surface parallel to said y-direction, said first gate coupleable to a first bias clock signal, synchronously generated by said clock generator, that is high during a first bias regime to detect and collect charge generated by at least a fraction of said incoming optical energy; a first source region formed in said substrate adjacent a distal end of said first gate; at least a second elongate-shaped polysilicon gate disposed on said surface parallel to said first elongate-shaped gate and spaced-apart in said x-direction a distance substantially shorter than a length of either said gate, said second gate coupleable to a second bias clock signal synchronously generated by said clock generator; a second source region formed in said substrate adjacent a distal end of said second gate; wherein responsive to said first bias clock signal and said second bias clock signal, photoelectic charge generated in said substrate is moved in said x direction to become trapped beneath an elongate-shaped gate and is then moved in said y-direction to an adjacent source region for collection, charge movement in said y-direction being slower than charge movement in said x-direction, wherein modulation contrast of said photodetector is enhanced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A CMOS-implementable semiconductor photodetector useable in a system that illuminates a target with optical energy having a modulated periodic waveform that includes a high frequency component, generated in response to a signal provided by a clock generator, and that detects a fraction of said optical energy reflected by said target with at least one said semiconductor photodetector, said photodetector comprising:
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a semiconductor substrate having a surface upon which said incoming optical energy can impinge onto an optical energy sensitive region, said surface defining an x-direction and a y-direction; at least a first elongate-shaped polysilicon gate disposed on said surface parallel to said y-direction, said first gate coupleable to a first bias clock signal, synchronously generated by said clock generator, that is high during a first bias regime to detect and collect charge generated by at least a fraction of said incoming optical energy; a first source region formed in said substrate adjacent a distal end of said first gate; a first bias gate disposed on said first surface intermediate a distal end of a said first elongated gate and said first source region adjacent said distal end, said first bias gate biasable to controllably inhibit carrier charge transfer from said first source region to said first elongated gate; wherein responsive to said first bias clock signal, photoelectric charge trapped in a region of said substrate beneath said first elongated gate is moved in said y-direction to said source region for collection, wherein transfer of charge from said source region to said first elongated gate is inhibited, and wherein modulation contrast of said photodetector is enhanced. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A CMOS-implementable semiconductor photodetector usable in a system to determine spectral composition of light illuminating a target object with optical energy and to detect a fraction of said optical energy reflected by said target object with at least one said semiconductor photodetector, said photodetector comprising:
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a semiconductor substrate having a surface upon which reflected said optical energy can impinge onto an optical energy sensitive region of said photodetector, said surface defining an x-direction and a y-direction; at least a first elongate-shaped polysilicon gate disposed on said surface parallel to said y-direction, said first gate coupleable to a first bias signal that is high during a first bias regime to detect and collect charge generated by at least a fraction of reflected said optical energy; a first source region formed in said substrate adjacent a distal end of said first gate; at least a second elongate-shaped polysilicon gate disposed on said surface parallel to said first elongate-shaped gate and spaced-apart in said x-direction a distance substantially shorter than a length of either said gate, said second gate coupleable to a second bias signal that is high during the first bias regime; a second source region formed in said substrate adjacent a distal end of said second gate; wherein responsive to said first bias signal and said second bias signal, photoelectric charge generated in said substrate is moved in said x direction to become trapped beneath an elongate-shaped said gate and is then moved in said y-direction to an adjacent source region for collection, a relative amount of charge collected by each elongate shaped said gate being dependent upon wavelength of reflected said light and upon bias voltage magnitudes during said first bias regime. - View Dependent Claims (23)
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Specification