Solid-State Image Sensor Pixel Voltage Control for Defect Reduction
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Solution Overview
Problem
Variation in the voltage of the charge retention unit in solid-state imaging devices leads to leakage current variations among pixels, resulting in point defects and decreased imaging quality due to direct connection between the charge retention unit and the photoelectric conversion unit.
Innovation Solution
Incorporating a voltage control transistor to regulate the output end voltage of the output transistor, reducing voltage variation in the charge retention unit and improving imaging quality by stabilizing the voltage applied to the photoelectric conversion unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the charge retention unit is directly connected to the photoelectric conversion unit, then the structure is simple and easy to manufacture, but voltage variation occurs leading to leakage current and point defects
Solution Approach 1:
A voltage control transistor is introduced as an intermediary component between the charge retention unit and the photoelectric conversion unit. This transistor regulates the voltage applied to the charge retention unit, preventing voltage variation and the resulting leakage current that causes point defects, while maintaining overall structural simplicity
Solution Approach 2:
The voltage control transistor dynamically adjusts the voltage parameter applied to the charge retention unit based on operational conditions. By changing the voltage level appropriately, the system prevents excessive voltage variation that would otherwise cause leakage current and imaging defects
2Object-generated harmful factors
If the voltage of the charge retention unit is lowered to reduce leakage current, then leakage current decreases, but voltage variation among pixels increases causing point defects
Solution Approach 1:
The voltage control transistor operates with feedback control to maintain appropriate voltage levels across all pixels. By monitoring and adjusting the voltage applied to the charge retention unit, the system ensures uniform voltage distribution while keeping leakage current at acceptable levels, preventing point defects
3Reliability
If a stacked solid-state imaging device with multiple photoelectric conversion regions is used, then sensitivity decreases due to light absorption are reduced, but device complexity increases
Solution Approach 1:
The voltage control transistor serves multiple functions: it regulates voltage for the charge retention unit, prevents leakage current, maintains voltage uniformity across pixels, and works with the stacked photoelectric conversion structure. This multi-functional component manages the complexity while enabling the benefits of the stacked configuration
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
The implementation of a voltage control transistor effectively reduces voltage variation in the charge retention unit, minimizing leakage current and enhancing imaging quality by maintaining consistent voltage for the photoelectric conversion unit.
Implementation Method 1
a first photoelectric conversion unit that generates and accumulates signal charge by receiving light having entered the pixel and photoelectrically converting the light
Data Source
AI summary
The present technology relates to a solid-state imaging device that can improve imaging quality by reducing variation in the voltage of a charge retention unit, a method of driving the solid-state imaging device, and an electronic apparatus. A first photoelectric conversion unit generates and accumulates signal charge by receiving light that has entered a pixel, and photoelectrically converting the light. A first charge retention unit retains the generated signal charge. A first output transistor outputs the signal charge in the first charge retention unit as a pixel signal, when the pixel is selected by the first select transistor. A first voltage control transistor controls the voltage of the output end of the first output transistor. The present technology can be applied to pixels in solid-state imaging devices, for example.