Solid State Imaging Device 3D Stacked Charge Accumulation
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Solution Overview
Problem
CMOS solid-state imaging devices with global shutter function face challenges due to increased chip size and limited light receiving area, leading to higher costs and reduced image quality when capturing fast-moving subjects.
Innovation Solution
The solution involves forming photoelectric converter sections on a first substrate and charge accumulation capacitor sections on a second substrate, with MOS transistors on the second substrate, allowing for electrical connection and reducing chip size while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photoelectric converter sections and accumulation capacitor sections are formed on the same substrate surface, then the device can achieve global shutter function, but the chip area increases
Solution Approach 1:
The patent applies three-dimensional stacking to separate the photoelectric converter sections and accumulation capacitor sections onto different substrate surfaces. Specifically, the photoelectric converter sections are formed on a first substrate surface, while the accumulation capacitor sections are formed on a second substrate surface at positions corresponding to the photoelectric converter sections. This vertical separation resolves the area conflict by utilizing the third dimension (depth/stacking direction) rather than expanding horizontally.
Solution Approach 2:
The patent divides the imaging device into functionally separate sections located on different substrate surfaces. The first substrate contains photoelectric converter sections for charge generation, while the second substrate contains accumulation capacitor sections for charge storage. This segmentation allows each component to be optimized independently and reduces the overlapping area required when both components are integrated on the same surface.
2Adaptability or versatility
If accumulation capacitor sections are formed on the same substrate surface, then charge accumulation is enabled, but the light receiving area of photoelectric converter section is limited
Solution Approach 1:
By moving the accumulation capacitor sections to a second substrate surface in the vertical direction, the patent eliminates the horizontal space competition between photoelectric converter sections and accumulation capacitor sections. This allows the photoelectric converter sections to maximize their light receiving area on the first substrate surface without being constrained by the footprint of the accumulation capacitor sections.
3Area of stationary object
If photoelectric converter sections and accumulation capacitor sections are formed on different substrate surfaces, then chip size is reduced, but electrical connection between substrates is required
Solution Approach 1:
The connection electrodes serve multiple functions: they provide electrical connection between the photoelectric converter sections on the first substrate and the accumulation capacitor sections on the second substrate, and they also serve as part of the signal readout path. This multi-functionality reduces the need for separate connection structures and simplifies the overall device architecture despite the multi-substrate 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
This approach reduces chip size and cost, enhances light receiving area, and improves image capture by enabling simultaneous charge accumulation and transfer across all pixels, addressing the limitations of traditional CMOS devices.
Implementation Method 1
signal charges generated by and accumulated in the photoelectric converter section
Data Source
AI summary
A solid-state imaging device includes a plurality of pixels, each of which includes a photoelectric converter section formed on a first substrate to generate and accumulate signal charges corresponding to incident light, a charge accumulation capacitor section formed on the first substrate or a second substrate to temporarily hold the signal charges transferred from the photoelectric converter section, and a plurality of MOS transistors formed on the second substrate to transfer the signal charges accumulated in the charge accumulation capacitor section, connection electrodes formed on the first substrate, and connection electrodes formed on the second substrate and electrically connected to the connection electrodes formed on the first substrate.