Global Shutter Pixel Charge Storage With Stacked Holding Sections
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Solution Overview
Problem
The capacity of the charge holding section in imaging devices using the global shutter method is insufficient, making it difficult to secure a region for the charge holding section as pixel size decreases with higher resolution, preventing the application of the global shutter method.
Innovation Solution
An imaging device with a photoelectric converter, a first charge holding section, an auxiliary charge holding section, and a transfer route formed in the semiconductor substrate, where the auxiliary charge holding section underlies the first charge holding section to increase charge capacity without increasing the footprint, allowing for efficient charge transfer and image signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is reduced to achieve higher resolution, then imaging resolution is improved, but the area available for charge holding section is reduced
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement to a three-dimensional stacked configuration by placing the auxiliary charge holding section beneath the first charge holding section in the depth direction. This vertical stacking enables additional charge storage capacity without increasing the lateral footprint, effectively resolving the contradiction between high resolution (small pixel size) and sufficient charge holding capacity.
2Measurement precision
If a global shutter method is implemented, then image quality is improved by preventing distortion, but the charge holding capacity requirements increase
Solution Approach 1:
The patent implements a nested structure where the auxiliary charge holding section is positioned beneath the first charge holding section, with both sections vertically stacked within the same pixel footprint. This nesting approach allows the system to accumulate sufficient charge capacity for global shutter operation while maintaining compact pixel dimensions, thereby enabling high-quality imaging without distortion.
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 configuration effectively increases the charge holding capacity of the imaging device, enabling the use of the global shutter method while maintaining a compact pixel design, thus preventing image distortion and ensuring high-quality imaging.
Implementation Method 1
a photoelectric converter that performs photoelectric conversion on incident light and generates a charge depending on the incident light
Data Source
AI summary
To increase the capacity of a charge holding section of a pixel in an imaging device that performs imaging using a global shutter method. An imaging device includes a photoelectric converter, a first charge holding section, an auxiliary charge holding section, a transfer route, and an image signal generator. The first charge holding section is formed near a front surface of a semiconductor substrate. A first charge transfer section transfers charge from the photoelectric converter to the first charge holding section. The auxiliary charge holding section underlies the first charge holding section, and holds a portion of the charges held in the first charge holding section. The transfer route transfers the charge between the first charge holding section and the auxiliary charge holding section. The image signal generator generates an image signal based on the charges held in the first charge holding section and the auxiliary charge holding section.