Image Sensor Floating Diffusion Connector for Low-Coupling Routing
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Solution Overview
Problem
Existing image sensors face challenges in efficiently connecting floating diffusion regions, leading to increased coupling among wires and reduced freedom in wire disposition, which affects the overall performance and design flexibility.
Innovation Solution
The implementation of a floating diffusion region connector buried in a shallow trench isolation structure, which connects at least two floating diffusion regions and has an upper surface lower than the shallow trench isolation structure, reducing capacitive coupling and enhancing wire routing flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If floating diffusion regions are connected using conventional wiring structures, then electrical connection is achieved, but parasitic capacitance increases and wire routing flexibility decreases
Solution Approach 1:
The patent introduces a dedicated floating diffusion region connector as an intermediary element that provides a low-capacitance electrical connection path between floating diffusion regions. This connector is specifically designed with low parasitic capacitance characteristics to minimize harmful capacitive coupling while maintaining reliable electrical connectivity, thereby resolving the contradiction between connection quality and parasitic capacitance reduction.
Solution Approach 2:
The patent changes the electrical parameters of the connection structure by using materials and geometries optimized for low capacitance. The floating diffusion region connector employs specific material compositions and structural dimensions that reduce parasitic capacitance compared to conventional wiring, enabling improved electrical connection quality with minimized harmful capacitive effects.
2Reliability
If conventional wiring structures are used to connect floating diffusion regions, then electrical connectivity is established, but wire routing freedom is reduced
Solution Approach 1:
The patent segments the connection function by introducing a specialized floating diffusion region connector that is distinct from conventional wiring structures. This segmentation allows the connector to be independently optimized for low capacitance and integrated at specific locations within the pixel structure, thereby maintaining electrical connectivity while providing greater freedom in wire routing arrangements.
Solution Approach 2:
The patent utilizes the vertical dimension by embedding the floating diffusion region connector within the pixel structure's depth, rather than relying solely on planar wiring. This dimensional change enables electrical connection without constraining wire routing in the horizontal plane, thereby improving both connectivity and routing flexibility.
3Productivity
If floating diffusion regions are closely spaced to increase pixel density, then pixel integration is improved, but coupling between regions increases
Solution Approach 1:
The floating diffusion region connector serves as an intermediary that enables close spacing of floating diffusion regions while maintaining electrical isolation. By providing a dedicated low-capacitance connection path, the connector allows regions to be positioned closer together for higher integration density without increasing parasitic coupling between adjacent regions.
Solution Approach 2:
The patent applies local quality optimization by implementing the floating diffusion region connector specifically at locations where electrical connection is needed, while maintaining physical separation and isolation in other areas. This localized approach enables close spacing for integration density without allowing unwanted coupling between regions.
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 solution reduces parasitic capacitance and allows for more flexible wire routing, improving the design and performance of image sensors by minimizing coupling between wires and increasing the freedom of wire disposition.
Implementation Method 1
Each of the pixels includes a plurality of photodiodes for converting incident light into an electric signal
Data Source
AI summary
An image sensor includes a first substrate having a first side and a second side opposite each other, and including a pixel array region having plurality of active regions disposed at the first side, a shallow trench isolation structure disposed at the first side of the first substrate and isolating each of the plurality of active regions, a plurality of floating diffusion regions disposed at the plurality of active regions of the first substrate, and a floating diffusion region connector connecting the plurality of floating diffusion regions with each other. The floating diffusion region connector is buried in the shallow trench isolation structure and an upper surface of the floating diffusion region connector is lower than an upper surface of the shallow trench isolation structure.