Stacked Image Sensor Coupling Layout for Miniaturized Pixel Transfer
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Solution Overview
Problem
Solid-state imaging devices face limitations in design flexibility due to constraints in miniaturization and signal charge transfer efficiency, particularly in the coupling area between semiconductor layers, which affects the performance and noise levels in pixel arrays.
Innovation Solution
A solid-state imaging device with a stacked structure featuring a pixel separation section in one semiconductor layer and a shared coupling section between layers, utilizing three-dimensional coupling to increase the contact area and reduce resistance components in the signal charge transfer path, allowing for improved design freedom and miniaturization without compromising coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If planar coupling is used between electric charge accumulation sections and shared coupling section, then device structure is simple, but contact area is small and resistance is high
Solution Approach 1:
The patent transitions from planar (2D) coupling to three-dimensional coupling by extending the shared coupling section vertically to contact multiple electric charge accumulation sections at different depths. This dimensional change increases the contact area between the shared coupling section and multiple accumulation sections, thereby reducing resistance components in the signal charge transfer path while maintaining reasonable structural complexity
2Productivity
If pixel size is reduced for miniaturization, then device density increases, but coupling area between shared coupling section and electric charge accumulation sections decreases
Solution Approach 1:
By implementing three-dimensional coupling where the shared coupling section extends vertically to contact multiple electric charge accumulation sections, the patent compensates for the reduced horizontal coupling area resulting from pixel miniaturization. The vertical extension maintains sufficient coupling area despite smaller pixel footprints, preserving signal charge transfer efficiency while enabling higher pixel density
3Reliability
If three-dimensional coupling is implemented, then contact area increases and resistance decreases, but device structure becomes more complex
Solution Approach 1:
The patent divides the device into stacked semiconductor layers with distinct functional sections: a first semiconductor layer containing photoelectric conversion sections and electric charge accumulation sections, and a second semiconductor layer containing pixel transistors. The pixel separation section further segments pixels vertically. This segmentation allows three-dimensional coupling to be implemented in a structured manner, reducing the negative impact of increased complexity while maintaining improved signal charge transfer efficiency
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 enhances the imaging device's ability to maintain high signal transfer efficiency and reduce noise even in miniaturized pixel sizes, thereby improving image quality and design flexibility.
Implementation Method 1
Each of the pixels includes a photodiode PD
Data Source
AI summary
A solid-state imaging device according to an embodiment of the present disclosure includes a first semiconductor layer and a second semiconductor layer that are stacked. The first semiconductor layer includes a photoelectric conversion section and an electric charge accumulation section for each of pixels. The electric charge accumulation section accumulates signal charge generated in the photoelectric conversion section. The second semiconductor layer includes a pixel transistor that reads out the signal charge of the electric charge accumulation section. This solid-state imaging device includes a pixel separation section and a shared coupling section. The pixel separation section is provided in the first semiconductor layer. The pixel separation section partitions a plurality of the pixels from each other. The shared coupling section is provided between the second semiconductor layer and the first semiconductor layer. The shared coupling section is provided across the pixel separation section. In addition, the shared coupling section is in contact with a plurality of the electric charge accumulation sections. Coupling between each of the electric charge accumulation sections and the shared coupling section includes three-dimensional coupling.