Solid-State Image Sensor Pixel Structure for Charge Sorting
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Solution Overview
Problem
The existing pixel structures for solid-state image sensors used in optical time-of-flight measurement methods face issues such as residual electrons in photodiodes, uncertain electron transfer to distribution gates, and inefficiencies due to manufacturing accuracy errors, leading to suboptimal performance in high-speed operations.
Innovation Solution
The proposed pixel structure incorporates a three-stage gate structure with a read-out gate, a movement gate, and multiple distribution gates, where electrons are moved to form a gradient on the photodiode potential and are intensively transferred near the distribution gates' boundaries, ensuring efficient and balanced electron distribution, and symmetrically arranged elements to mitigate manufacturing inaccuracies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photogate structure is employed in the photoelectric conversion section to eliminate charge residue and generate a potential difference exceeding threshold value variation, then charge residue is eliminated and electron distribution is improved, but the photoelectric conversion efficiency to long wavelength light becomes low
Solution Approach 1:
The patent introduces an intermediate structure (the specific gate configuration with controlled potential distribution) between the photogate and charge storage sections to mediate the electron transport process, allowing long wavelength light detection while maintaining charge residue elimination through the potential difference mechanism
Solution Approach 2:
The patent modifies the potential distribution parameters in the photoelectric conversion section by controlling the gate voltages to create a potential difference that exceeds threshold value variation, enabling effective charge residue elimination while optimizing the structure for long wavelength light sensitivity
2Productivity
If high-frequency pulse voltage is applied to gate electrodes to distribute electrons to charge-storage sections, then electron distribution is achieved, but variation in threshold value causes incorrect distribution to adjacent charge-storage sections
Solution Approach 1:
The patent applies different voltage levels and timing to different gate electrodes based on their local characteristics and position, creating localized potential wells that guide electrons to the correct charge-storage sections despite manufacturing variations in threshold values
3Manufacturing precision
If a three-stage gate structure is used to improve electron transfer control, then electron distribution accuracy is improved, but device complexity increases
Solution Approach 1:
The patent divides the electron transfer control function into three distinct stages (first gate, second gate, and third gate), each performing a specific function in the electron distribution sequence, which allows for better control accuracy while maintaining modular simplicity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design significantly reduces residual electrons in photodiodes, ensures secure electron transfer to charge-storage sections, and minimizes inefficiencies caused by manufacturing errors, enhancing the overall charge sort efficiency and accuracy in high-speed operations.
Implementation Method 1
a photodiode that generates photoelectrons by photoelectric conversion
Implementation Method 2
the gate structure controls movement of photoelectrons generated in the photodiode to a plurality of charge-storage sections
Data Source
AI summary
A pixel structure of a solid-state image sensor in which residual electrons in a photodiode is reduced and which has a first-stage gate that is arranged adjacent to the photodiode and controls read-out of electrons generated in the photodiode, a second-stage gate that is adjacent to the first-stage gate on the rear stage of the gate at a predetermined gap and controls movement of electrons read out by the readout control of the first-stage gate to the plurality of the charge-storage sections, and a plurality of third-stage gates that are adjacent to the second-stage gate on the rear stage of the gate at a predetermined gap, severally arranged corresponding to the plurality of the charge-storage sections, and perform control of distributing the electrons moved by the movement control of the second-stage gate severally to the plurality of the charge-storage sections, and gradient on which electrons are moved in the first-stage gate direction is formed on the potential of the photodiode.